May Han, MD

All Publications

• Molecular signature of Epstein-Barr virus infection in MS brain lesions. Neurology(R) neuroimmunology & neuroinflammation Moreno, M. A., Or-Geva, N., Aftab, B. T., Khanna, R., Croze, E., Steinman, L., Han, M. H. 2018; 5 (4): e466

  Abstract

  Objective: We sought to confirm the presence and frequency of B cells and Epstein-Barr virus (EBV) (latent and lytic phase) antigens in archived MS and non-MS brain tissue by immunohistochemistry.Methods: We quantified the type and location of B-cell subsets within active and chronic MS brain lesions in relation to viral antigen expression. The presence of EBV-infected cells was further confirmed by in situ hybridization to detect the EBV RNA transcript, EBV-encoded RNA-1 (EBER-1).Results: We report the presence of EBV latent membrane protein 1 (LMP-1) in 93% of MS and 78% of control brains, with a greater percentage of MS brains containing CD138+ plasma cells and LMP-1-rich populations. Notably, 78% of chronic MS lesions and 33.3% of non-MS brains contained parenchymal CD138+ plasma cells. EBV early lytic protein, EBV immediate-early lytic gene (BZLF1), was also observed in 46% of MS, primarily in association with chronic lesions and 44% of non-MS brain tissue. Furthermore, 85% of MS brains revealed frequent EBER-positive cells, whereas non-MS brains seldom contained EBER-positive cells. EBV infection was detectable, by immunohistochemistry and by in situ hybridization, in both MS and non-MS brains, although latent virus was more prevalent in MS brains, while lytic virus was restricted to chronic MS lesions.Conclusions: Together, our observations suggest an uncharacterized link between the EBV virus life cycle and MS pathogenesis.

  View details for DOI 10.1212/NXI.0000000000000466

  View details for PubMedID 29892607

• Investigating Immune Phenotype Biomarker Changes in Patients with Relapsing MS Treated with Fingolimod 0.5 Mg/Day: The Fluent Study Cohen, J. A., Bar-Or, A., Cree, B. C., Mao-Draayer, Y., Han, M. H., Singer, B. A., Jannu, A., Kolodny, S., Meng, X., Winger, R. SAGE PUBLICATIONS LTD. 2018: 14

  View details for Web of Science ID 000429034600031

• Fibrinogen Activates BMP Signaling in Oligodendrocyte Progenitor Cells and Inhibits Remyelination after Vascular Damage NEURON Petersen, M. A., Ryu, J., Chang, K., Etxeberria, A., Bardehle, S., Mendiola, A. S., Kamau-Devers, W., Fancy, S. J., Thor, A., Bushong, E. A., Baeza-Raja, B., Syme, C. A., Wu, M. D., Coronado, P., Meyer-Franke, A., Yahn, S., Pous, L., Lee, J. K., Schachtrup, C., Lassmann, H., Huang, E. J., Han, M. H., Absinta, M., Reich, D. S., Ellisman, M. H., Rowitch, D. H., Chan, J. R., Akassoglou, K. 2017; 96 (5): 1003-+

  Abstract

  Blood-brain barrier (BBB) disruption alters the composition of the brain microenvironment by allowing blood proteins into the CNS. However, whether blood-derived molecules serve as extrinsic inhibitors of remyelination is unknown. Here we show that the coagulation factor fibrinogen activates the bone morphogenetic protein (BMP) signaling pathway in oligodendrocyte progenitor cells (OPCs) and suppresses remyelination. Fibrinogen induces phosphorylation of Smad 1/5/8 and inhibits OPC differentiation into myelinating oligodendrocytes (OLs) while promoting an astrocytic fate in vitro. Fibrinogen effects are rescued by BMP type I receptor inhibition using dorsomorphin homolog 1 (DMH1) or CRISPR/Cas9 activin A receptor type I (ACVR1) knockout in OPCs. Fibrinogen and the BMP target Id2 are increased in demyelinated multiple sclerosis (MS) lesions. Therapeutic depletion of fibrinogen decreases BMP signaling and enhances remyelination in vivo. Targeting fibrinogen may be an upstream therapeutic strategy to promote the regenerative potential of CNS progenitors in diseases with remyelination failure.

  View details for DOI 10.1016/j.neuron.2017.10.008

  View details for Web of Science ID 000417336100009

  View details for PubMedID 29103804

  View details for PubMedCentralID PMC5851281

• Phosphorylation of aB-crystallin supports reactive astrogliosis in demyelination. Proceedings of the National Academy of Sciences of the United States of America Kuipers, H. F., Yoon, J., van Horssen, J., Han, M. H., Bollyky, P. L., Palmer, T. D., Steinman, L. 2017; 114 (9): E1745-E1754

  Abstract

  The small heat shock protein αB-crystallin (CRYAB) has been implicated in multiple sclerosis (MS) pathogenesis. Earlier studies have indicated that CRYAB inhibits inflammation and attenuates clinical disease when administered in the experimental autoimmune encephalomyelitis model of MS. In this study, we evaluated the role of CRYAB in primary demyelinating events. Using the cuprizone model of demyelination, a noninflammatory model that allows the analysis of glial responses in MS, we show that endogenous CRYAB expression is associated with increased severity of demyelination. Moreover, we demonstrate a strong correlation between the expression of CRYAB and the extent of reactive astrogliosis in demyelinating areas and in in vitro assays. In addition, we reveal that CRYAB is differentially phosphorylated in astrocytes in active demyelinating MS lesions, as well as in cuprizone-induced lesions, and that this phosphorylation is required for the reactive astrocyte response associated with demyelination. Furthermore, taking a proteomics approach to identify proteins that are bound by the phosphorylated forms of CRYAB in primary cultured astrocytes, we show that there is clear differential binding of protein targets due to the specific phosphorylation of CRYAB. Subsequent Ingenuity Pathway Analysis of these targets reveals implications for intracellular pathways and biological processes that could be affected by these modifications. Together, these findings demonstrate that astrocytes play a pivotal role in demyelination, making them a potential target for therapeutic intervention, and that phosphorylation of CRYAB is a key factor supporting the pathogenic response of astrocytes to oligodendrocyte injury.

  View details for DOI 10.1073/pnas.1621314114

  View details for PubMedID 28196893

  View details for PubMedCentralID PMC5338510

• Integrative proteomics, genomics, and translational immunology approaches reveal mutated forms of Proteolipid Protein 1 (PLP1) and mutant-specific immune response in multiple sclerosis. Proteomics Qendro, V., Bugos, G. A., Lundgren, D. H., Glynn, J., Han, M. H., Han, D. K. 2017

  Abstract

  In order to gain mechanistic insights into multiple sclerosis (MS) pathogenesis, we utilized a multi-dimensional approach to test the hypothesis that mutations in myelin proteins lead to immune activation and central nervous system autoimmunity in MS. Mass spectrometry-based proteomic analysis of human MS brain lesions revealed seven unique mutations of PLP1; a key myelin protein that is known to be destroyed in MS. Surprisingly, in-depth genomic analysis of two MS patients at the genomic DNA and mRNA confirmed mutated PLP1 in RNA, but not in the genomic DNA. Quantification of wild type and mutant PLP RNA levels by qPCR further validated the presence of mutant PLP RNA in the MS patients. To seek evidence linking mutations in abundant myelin proteins and immune-mediated destruction of myelin, specific immune response against mutant PLP1 in MS patients was examined. Thus, we have designed paired, wild type and mutant peptide microarrays, and examined antibody response to multiple mutated PLP1 in sera from MS patients. Consistent with the idea of different patients exhibiting unique mutation profiles, we found that 13 out of 20 MS patients showed antibody responses against specific but not against all the mutant-PLP1 peptides. Interestingly, we found mutant PLP-directed antibody response against specific mutant peptides in the sera of pre-MS controls. The results from integrative proteomic, genomic, and immune analyses reveal a possible mechanism of mutation-driven pathogenesis in human MS. The study also highlights the need for integrative genomic and proteomic analyses for uncovering pathogenic mechanisms of human diseases.

  View details for DOI 10.1002/pmic.201600322

  View details for PubMedID 28191734

• Imaging B cells in a mouse model of multiple sclerosis using (64)Cu-Rituximab-PET. Journal of nuclear medicine : official publication, Society of Nuclear Medicine James, M. L., Hoehne, A., Mayer, A. T., Lechtenberg, K., Moreno, M., Gowrishankar, G., Ilovich, O., Natarajan, A., Johnson, E. M., Nguyen, J., Quach, L., Han, M., Buckwalter, M., Chandra, S., Gambhir, S. S. 2017

  Abstract

  B lymphocytes are a key pathological feature of multiple sclerosis (MS), and are becoming an important therapeutic target for this condition. Currently, there is no approved technique to non-invasively visualize B cells in the central nervous system (CNS) to monitor MS disease progression and response to therapies. Here we evaluated (64)Cu-Rituximab, a radiolabeled antibody specifically targeting the human B cell marker CD20, for its ability to image B cells in a mouse model of MS using positron emission tomography (PET). Methods: To model CNS infiltration by B cells, experimental autoimmune encephalomyelitis (EAE) was induced in transgenic mice that express human CD20 on B cells. EAE mice were given subcutaneous injections of Myelin Oligodendrocyte Glycoprotein fragment1-125 (MOG1-125) emulsified in complete Freund's adjuvant. Control mice received complete Freund's adjuvant alone. PET imaging of EAE and control mice was performed 1, 4, and 19h following (64)Cu-Rituximab administration. Mice were perfused and sacrificed after final PET scan, and radioactivity in dissected tissues was measured with a gamma-counter. CNS tissues from these mice were immunostained to quantify B cells or further analyzed via digital autoradiography. Results: Lumbar spinal cord PET signal was significantly higher in EAE mice compared to controls at all evaluated time points (e.g., 1h post-injection: 5.44 ± 0.37 vs. 3.33 ± 0.20 %ID/g, p<0.05). (64)Cu-Rituximab-PET signal in brain regions ranged between 1.74 ± 0.11 and 2.93 ± 0.15 %ID/g for EAE mice compared to 1.25±0.08 and 2.24±0.11%ID/g for controls, p<0.05 for all regions except striatum and thalamus at 1h post-injection. Similarly, ex vivo biodistribution results revealed notably higher (64)Cu-Rituximab uptake in brain and spinal cord of huCD20tg EAE, and B220 immunostaining verified that increased (64)Cu-Rituximab uptake in CNS tissues corresponded with elevated B cells. Conclusion: B cells can be detected in the CNS of EAE mice using (64)Cu-Rituximab-PET. Results from these studies warrant further investigation of (64)Cu-Rituximab in EAE models and consideration of use in MS patients to evaluate its potential for detecting and monitoring B cells in the progression and treatment of this disease. These results represent an initial step toward generating a platform to evaluate B cell-targeted therapeutics en route to the clinic.

  View details for DOI 10.2967/jnumed.117.189597

  View details for PubMedID 28687602

• Exosomal proteome analysis of cerebrospinal fluid detects biosignatures of neuromyelitis optica and multiple sclerosis. Clinica chimica acta; international journal of clinical chemistry Lee, J., McKinney, K. Q., Pavlopoulos, A. J., Han, M. H., Kim, S., Kim, H. J., Hwang, S. 2016; 462: 118-126

  Abstract

  Quantitative proteomic analysis of exosomes isolated from cerebrospinal fluid (CSF) of neuromyelitis optica (NMO) patients detected signature proteins differentiating NMO from multiple sclerosis (MS) and idiopathic longitudinally extensive transverse myelitis. Exosomes with good yields were obtained using ultracentrifugation from pooled CSF assisted by chemokine-based clustering strategy, which improved target molecule identification by providing amplified fold change values. 442 significant proteins generated a list of signature molecules of diseases validated primarily by the identification of known markers such as glial fibrillary acidic protein (GFAP) and fibronectin specific to NMO and MS respectively. MetaCore pathway analysis of significant proteins supported the involvement of these proteins in disease progression via neurological pathway. Expression levels of target molecules from orthogonal label-free quantification employing quadrupole-Orbitrap hybrid mass spectrometry were in good agreement with those from Western blotting. Additional investigation of GFAP and fibronectin as representative disease molecules revealed their presence in intact exosomes as detected by flow cytometry. This comprehensive study suggests that the exosomal proteomic analysis of CSF can be applied to the identification and characterization of inflammatory disorders of the central nervous system.

  View details for DOI 10.1016/j.cca.2016.09.001

  View details for PubMedID 27609124

• In Vivo 7T MR Quantitative Susceptibility Mapping Reveals Opposite Susceptibility Contrast between Cortical and White Matter Lesions in Multiple Sclerosis AMERICAN JOURNAL OF NEURORADIOLOGY Bian, W., Tranvinh, E., Tourdias, T., Han, M., Liu, T., Wang, Y., Rutt, B., Zeineh, M. M. 2016; 37 (10): 1808-1815

  Abstract

  Magnetic susceptibility measured with quantitative susceptibility mapping has been proposed as a biomarker for demyelination and inflammation in patients with MS, but investigations have mostly been on white matter lesions. A detailed characterization of cortical lesions has not been performed. The purpose of this study was to evaluate magnetic susceptibility in both cortical and WM lesions in MS by using quantitative susceptibility mapping.Fourteen patients with MS were scanned on a 7T MR imaging scanner with T1-, T2-, and T2*-weighted sequences. The T2*-weighted sequence was used to perform quantitative susceptibility mapping and generate tissue susceptibility maps. The susceptibility contrast of a lesion was quantified as the relative susceptibility between the lesion and its adjacent normal-appearing parenchyma. The susceptibility difference between cortical and WM lesions was assessed by using a t test.The mean relative susceptibility was significantly negative for cortical lesions (P < 10(-7)) but positive for WM lesions (P < 10(-22)). A similar pattern was also observed in the cortical (P = .054) and WM portions (P = .043) of mixed lesions.The negative susceptibility in cortical lesions suggests that iron loss dominates the susceptibility contrast in cortical lesions. The opposite susceptibility contrast between cortical and WM lesions may reflect both their structural (degree of myelination) and pathologic (degree of inflammation) differences, in which the latter may lead to a faster release of iron in cortical lesions.

  View details for DOI 10.3174/ajnr.A4830

  View details for Web of Science ID 000383984600014

  View details for PubMedID 27282860

• Sphingosine-1-Phosphate (S1P) and S1P Signaling Pathway: Therapeutic Targets in Autoimmunity and Inflammation DRUGS Tsai, H., Han, M. H. 2016; 76 (11): 1067-1079

  Abstract

  Sphingosine-1-phosphate (S1P) and S1P receptors (S1PR) are ubiquitously expressed. S1P-S1PR signaling has been well characterized in immune trafficking and activation in innate and adaptive immune systems. However, the full extent of its involvement in the pathogenesis of autoimmune diseases is not well understood. FTY720 (fingolimod), a non-selective S1PR modulator, significantly decreased annualized relapse rates in relapsing-remitting multiple sclerosis (MS). FTY720, which primarily targets S1P receptor 1 as a functional antagonist, arrests lymphocyte egress from secondary lymphoid tissues and reduces neuroinflammation in the central nervous system (CNS). Recent studies suggest that FTY720 also decreases astrogliosis and promotes oligodendrocyte differentiation within the CNS and may have therapeutic benefit to prevent brain atrophy. Since S1P signaling is involved in multiple immune functions, therapies targeting S1P axis may be applicable to treat autoimmune diseases other than MS. Currently, over a dozen selective S1PR and S1P pathway modulators with potentially superior therapeutic efficacy and better side-effect profiles are in the pipeline of drug development. Furthermore, newly characterized molecules such as apolipoprotein M (ApoM) (S1P chaperon) and SPNS2 (S1P transporter) are also potential targets for treatment of autoimmune diseases. Finally, the application of therapies targeting S1P and S1P signaling pathways may be expanded to treat several other immune-mediated disorders (such as post-infectious diseases, post-stroke and post-stroke dementia) and inflammatory conditions beyond their application in primary autoimmune diseases.

  View details for DOI 10.1007/s40265-016-0603-2

  View details for Web of Science ID 000379497000001

  View details for PubMedID 27318702

• Intravenous Transplantation of Mesenchymal Progenitors Distribute Solely to the Lungs and Improve Outcomes in Cervical Spinal Cord Injury STEM CELLS White, S. V., Czisch, C. E., Han, M. H., Plant, C. D., Harvey, A. R., Plant, G. W. 2016; 34 (7): 1812-1825

  Abstract

  Cellular transplantation strategies utilizing intraspinal injection of mesenchymal progenitor cells have been reported as beneficial for spinal cord injuries. However, intraspinal injection is not only technically challenging, but requires invasive surgical procedures for patients. Therefore, we investigated the feasibility and potential benefits of non-invasive intravenous injection of mesenchymal progenitor cells in two models of cervical spinal cord injury, unilateral C5 contusion and complete unilateral C5 hemisection. Mesenchymal progenitor cells were isolated from GFP-luciferase transgenic mice compact bone (1x10(6) cells) or vehicle (HBSS) were intravenously injected via the tail vein at D1, D3, D7, D10 or D14. Transplanted mesenchymal progenitor cells were tracked via bioluminescence imaging. Live in vivo imaging data showed that intravenously injected mesenchymal progenitor cells accumulate in the lungs, confirmed by post-mortem bioluminescence signal - irrespective of the time of injection or injury model. The results showed a rapid, positive modulation of the inflammatory response providing protection to the injured spinal cord tissue. Histological processing of the lungs showed GFP(+) cells evenly distributed around the alveoli. We propose that injected cells can act as cellular target decoys to an immune system primed by injury, thereby lessening the inflammatory response at the injury site. We also propose that intravenous injected mesenchymal progenitor cells modulate the immune system via the lungs through secreted immune mediators or contact interaction with peripheral organs. In conclusion, the timing of intravenous injection of mesenchymal progenitor cells is key to the success for improving function and tissue preservation following cervical spinal cord injury. This article is protected by copyright. All rights reserved.

  View details for DOI 10.1002/stem.2364

  View details for Web of Science ID 000379902900009

  View details for PubMedID 26989838

• Effects of sphingosine-1-phosphate receptor 1 phosphorylation in response to FTY720 during neuroinflammation. JCI insight Tsai, H., Huang, Y., Garris, C. S., Moreno, M. A., Griffin, C. W., Han, M. H. 2016; 1 (9)

  Abstract

  Fingolimod (FTY720, Gilenya), a sphingosine-1-phosphate receptor (S1PR) modulator, is one of the first-line immunomodulatory therapies for treatment of relapsing-remitting multiple sclerosis (MS). Human S1PR1 variants have been reported to have functional heterogeneity in vitro, suggesting that S1PR1 function may influence FTY720 efficacy. In this study, we examined the influence of S1PR1 phosphorylation on response to FTY720 in neuroinflammation. We found that mice carrying a phosphorylation-defective S1pr1 gene [S1PR1(S5A) mice] were refractory to FTY720 treatment in MOG35-55-immunized and Th17-mediated experimental autoimmune encephalomyelitis (EAE) models. Long-term treatment with FTY720 induced significant lymphopenia and suppressed Th17 response in the peripheral immune system via downregulating STAT3 phosphorylation in both WT and S1PR1(S5A) mice. However, FTY720 did not effectively prevent neuroinflammation in the S1PR1(S5A) EAE mice as a result of encephalitogenic cells expressing C-C chemokine receptor 6 (CCR6). Combined treatment with FTY720 and anti-CCR6 delayed disease progression in S1PR1(S5A) EAE mice, suggesting that CCR6-mediated cell trafficking can overcome the effects of FTY720. This work may have translational relevance regarding FTY720 efficacy in MS patients and suggests that cell type-specific therapies may enhance therapeutic efficacy in MS.

  View details for PubMedID 27699272

  View details for PubMedCentralID PMC5033897

• Effects of sphingosine-1-phosphate receptor 1 phosphorylation in response to FTY720 during neuroinflammation JCI Insight Tsai, H. 2016; 1 (9)

  View details for DOI 10.1172/jci.insight.86462

• Acute and Chronic Management of Neuromyelitis Optica Spectrum Disorder CURRENT TREATMENT OPTIONS IN NEUROLOGY Sherman, E., Han, M. H. 2015; 17 (11)

  View details for DOI 10.1007/s11940-015-0378-x

  View details for Web of Science ID 000363959300002

  View details for PubMedID 26433388

• Update on biomarkers in neuromyelitis optica. Neurology® neuroimmunology & neuroinflammation Melamed, E., Levy, M., Waters, P. J., Sato, D. K., Bennett, J. L., John, G. R., Hooper, D. C., Saiz, A., Bar-Or, A., Kim, H. J., Pandit, L., Leite, M. I., Asgari, N., Kissani, N., Hintzen, R., Marignier, R., Jarius, S., Marcelletti, J., Smith, T. J., Yeaman, M. R., Han, M. H., Aktas, O., Apiwattanakul, M., Banwell, B., Bichuetti, D., Broadley, S., Cabre, P., Chitnis, T., de Seze, J., Fujihara, K., Greenberg, B., Hellwig, K., Iorio, R., Jarius, S., Klawiter, E., Kleiter, I., Lana-Peixoto, M., NAKASHIMA, O'Connor, K., Palace, J., Paul, F., Prayoonwiwat, N., Ruprecht, K., Stuve, O., Tedder, T., Tenembaum, S., Garrahan, J. P., Aires, B., Van Herle, K., Van Pelt, D., Villoslada, P., Waubant, E., Weinshenker, B., Wingerchuk, D., Würfel, J., Zamvil, S. 2015; 2 (4)

  Abstract

  Neuromyelitis optica (NMO) (and NMO spectrum disorder) is an autoimmune inflammatory disease of the CNS primarily affecting spinal cord and optic nerves. Reliable and sensitive biomarkers for onset, relapse, and progression in NMO are urgently needed because of the heterogeneous clinical presentation, severity of neurologic disability following relapses, and variability of therapeutic response. Detecting aquaporin-4 (AQP4) antibodies (AQP4-IgG or NMO-IgG) in serum supports the diagnosis of seropositive NMO. However, whether AQP4-IgG levels correlate with disease activity, severity, response to therapy, or long-term outcomes is unclear. Moreover, biomarkers for patients with seronegative NMO have yet to be defined and validated. Collaborative international studies hold great promise for establishing and validating biomarkers that are useful in therapeutic trials and clinical management. In this review, we discuss known and potential biomarkers for NMO.

  View details for DOI 10.1212/NXI.0000000000000134

  View details for PubMedID 26236760

• HDL-bound sphingosine-1-phosphate restrains lymphopoiesis and neuroinflammation. Nature Blaho, V. A., Galvani, S., Engelbrecht, E., Liu, C., Swendeman, S. L., Kono, M., Proia, R. L., Steinman, L., Han, M. H., Hla, T. 2015; 523 (7560): 342-346

  Abstract

  Lipid mediators influence immunity in myriad ways. For example, circulating sphingosine-1-phosphate (S1P) is a key regulator of lymphocyte egress. Although the majority of plasma S1P is bound to apolipoprotein M (ApoM) in the high-density lipoprotein (HDL) particle, the immunological functions of the ApoM-S1P complex are unknown. Here we show that ApoM-S1P is dispensable for lymphocyte trafficking yet restrains lymphopoiesis by activating the S1P1 receptor on bone marrow lymphocyte progenitors. Mice that lacked ApoM (Apom(-/-)) had increased proliferation of Lin(-) Sca-1(+) cKit(+) haematopoietic progenitor cells (LSKs) and common lymphoid progenitors (CLPs) in bone marrow. Pharmacological activation or genetic overexpression of S1P1 suppressed LSK and CLP cell proliferation in vivo. ApoM was stably associated with bone marrow CLPs, which showed active S1P1 signalling in vivo. Moreover, ApoM-bound S1P, but not albumin-bound S1P, inhibited lymphopoiesis in vitro. Upon immune stimulation, Apom(-/-) mice developed more severe experimental autoimmune encephalomyelitis, characterized by increased lymphocytes in the central nervous system and breakdown of the blood-brain barrier. Thus, the ApoM-S1P-S1P1 signalling axis restrains the lymphocyte compartment and, subsequently, adaptive immune responses. Unique biological functions imparted by specific S1P chaperones could be exploited for novel therapeutic opportunities.

  View details for DOI 10.1038/nature14462

  View details for PubMedID 26053123

  View details for PubMedCentralID PMC4506268

• Patient experience and practice trends in multiple sclerosis - clinical utility of fingolimod PATIENT PREFERENCE AND ADHERENCE Lee, J., Han, M. H. 2015; 9

  Abstract

  Targeting sphingosine-1-phosphate pathway with orally available immune-modulatory fingolimod (Gilenya™) therapy ameliorates relapsing-remitting multiple sclerosis (RRMS) by decreasing relapse rate as shown in FREEDOMS and TRANSFORMS. Fingolimod has also been shown to be superior to interferon-beta therapy as evidenced by TRANSFORMS. Albeit multiple benefits in treatment of multiple sclerosis including high efficacy and ease of administration, potential untoward effects such as cardiotoxicity, risk of infection, and cancer exist, thus mandating careful screening and frequent monitoring of patients undergoing treatment with fingolimod. This review outlines mechanism of action, observations, side effects, and practice guidelines on use of fingolimod in treatment of RRMS.

  View details for DOI 10.2147/PPA.S57354

  View details for Web of Science ID 000354946400001

  View details for PubMedID 26056436

  View details for PubMedCentralID PMC4446999

• Sphingosine-1-phosphate receptor 1 signalling in T cells: trafficking and beyond IMMUNOLOGY Garris, C. S., Blaho, V. A., Hla, T., Han, M. H. 2014; 142 (3): 347-353

  View details for DOI 10.1111/imm.12272

  View details for Web of Science ID 000337600500003

• Optimization of magnetization-prepared 3-dimensional fluid attenuated inversion recovery imaging for lesion detection at 7 T. Investigative radiology Saranathan, M., Tourdias, T., Kerr, A. B., Bernstein, J. D., Kerchner, G. A., Han, M. H., Rutt, B. K. 2014; 49 (5): 290-298

  Abstract

  The aim of this study was to optimize the 3-dimensional (3D) fluid attenuated inversion recovery (FLAIR) pulse sequence for isotropic high-spatial-resolution imaging of white matter (WM) and cortical lesions at 7 T.We added a magnetization-prepared (MP) FLAIR module to a Cube 3D fast spin echo sequence and optimized the refocusing flip angle train using extended phase graph simulations, taking into account image contrast, specific absorption rate (SAR), and signal-to-noise ratio (SNR) as well as T1/T2 values of the different species of interest (WM, grey matter, lesions) at 7 T. We also effected improved preparation homogeneity at 7 T by redesigning the refocusing pulse used in the MP segments. Two sets of refocusing flip angle trains-(a) an SNR-optimal and (b) a contrast-optimal set-were derived and used to scan 7 patients with Alzheimer disease/cognitive impairment and 7 patients with multiple sclerosis. Conventional constant refocusing flip MP-FLAIR images were also acquired for comparison. Lesion SNR, contrast, and lesion count were compared between the 2 optimized and the standard FLAIR sequences.Whole brain coverage with 0.8 mm isotropic spatial resolution in ∼5-minute scan times was achieved using the optimized 3D FLAIR sequences at clinically acceptable SAR levels. The SNR efficiency of the SNR-optimal sequence was significantly better than that of conventional constant refocusing flip MP-FLAIR sequence, whereas the scan time was reduced more than 2-fold (∼5 vs >10 minutes). The contrast efficiency of the contrast-optimal sequence was comparable with that of the constant refocusing flip sequence. Lesion load ascertained by lesion counting was not significantly different among the sequences.Magnetization-prepared FLAIR-Cube with refocusing flip angle trains optimized for SNR and contrast can be used to characterize WM and cortical lesions at 7 T with 0.8 mm isotropic resolution in short scan times and without SAR penalty.

  View details for DOI 10.1097/RLI.0000000000000041

  View details for PubMedID 24566291

• Defective sphingosine 1-phosphate receptor 1 (S1P1) phosphorylation exacerbates TH17-mediated autoimmune neuroinflammation. Nature immunology Garris, C. S., Wu, L., Acharya, S., Arac, A., Blaho, V. A., Huang, Y., Moon, B. S., Axtell, R. C., Ho, P. P., Steinberg, G. K., Lewis, D. B., Sobel, R. A., Han, D. K., Steinman, L., Snyder, M. P., Hla, T., Han, M. H. 2013; 14 (11): 1166-1172

  Abstract

  Sphingosine 1-phosphate (S1P) signaling regulates lymphocyte egress from lymphoid organs into systemic circulation. The sphingosine phosphate receptor 1 (S1P1) agonist FTY-720 (Gilenya) arrests immune trafficking and prevents multiple sclerosis (MS) relapses. However, alternative mechanisms of S1P-S1P1 signaling have been reported. Phosphoproteomic analysis of MS brain lesions revealed S1P1 phosphorylation on S351, a residue crucial for receptor internalization. Mutant mice harboring an S1pr1 gene encoding phosphorylation-deficient receptors (S1P1(S5A)) developed severe experimental autoimmune encephalomyelitis (EAE) due to autoimmunity mediated by interleukin 17 (IL-17)-producing helper T cells (TH17 cells) in the peripheral immune and nervous system. S1P1 directly activated the Jak-STAT3 signal-transduction pathway via IL-6. Impaired S1P1 phosphorylation enhances TH17 polarization and exacerbates autoimmune neuroinflammation. These mechanisms may be pathogenic in MS.

  View details for DOI 10.1038/ni.2730

  View details for PubMedID 24076635

• Piet Mondrian's trees and the evolution in understanding multiple sclerosis, Charcot Prize Lecture 2011 MULTIPLE SCLEROSIS JOURNAL Steinman, L., Axtell, R. C., Barbieri, D., Bhat, R., Brownell, S. E., de Jong, B. A., Dunn, S. E., Grant, J. L., Han, M. H., Ho, P. P., Kuipers, H. F., Kurnellas, M. P., Ousman, S. S., Rothbard, J. B. 2013; 19 (1): 5-14

  Abstract

  Four questions were posed about multiple sclerosis (MS) at the 2011 Charcot Lecture, Oct. 22, 2011. 1. The Male/Female Disparity: Why are women developing MS so much more frequently than men? 2. Neuronal and Glial Protection: Are there guardian molecules that protect the nervous system in MS? 3. Predictive Medicine: With all the approved drugs, how can we rationally decide which one to use? 4. The Precise Scalpel vs. the Big Hammer for Therapy: Is antigen-specific therapy for demyelinating disease possible? To emphasize how our views on the pathogenesis and treatment of MS are evolving, and given the location of the talk in Amsterdam, Piet Mondrian's progressive interpretations of trees serve as a heuristic.

  View details for DOI 10.1177/1352458512470730

  View details for Web of Science ID 000313272100003

  View details for PubMedID 23303879

• Janus-like opposing roles of CD47 in autoimmune brain inflammation in humans and mice JOURNAL OF EXPERIMENTAL MEDICINE Han, M. H., Lundgren, D. H., Jaiswal, S., Chao, M., Graham, K. L., Garris, C. S., Axtell, R. C., Ho, P. P., Lock, C. B., Woodard, J. I., Brownell, S. E., Zoudilova, M., Hunt, J. F., Baranzini, S. E., Butcher, E. C., Raine, C. S., Sobel, R. A., Han, D. K., Weissman, I., Steinman, L. 2012; 209 (7): 1325-1334

  Abstract

  Comparison of transcriptomic and proteomic data from pathologically similar multiple sclerosis (MS) lesions reveals down-regulation of CD47 at the messenger RNA level and low abundance at the protein level. Immunohistochemical studies demonstrate that CD47 is expressed in normal myelin and in foamy macrophages and reactive astrocytes within active MS lesions. We demonstrate that CD47(-/-) mice are refractory to experimental autoimmune encephalomyelitis (EAE), primarily as the result of failure of immune cell activation after immunization with myelin antigen. In contrast, blocking with a monoclonal antibody against CD47 in mice at the peak of paralysis worsens EAE severity and enhances immune activation in the peripheral immune system. In vitro assays demonstrate that blocking CD47 also promotes phagocytosis of myelin and that this effect is dependent on signal regulatory protein α (SIRP-α). Immune regulation and phagocytosis are mechanisms for CD47 signaling in autoimmune neuroinflammation. Depending on the cell type, location, and disease stage, CD47 has Janus-like roles, with opposing effects on EAE pathogenesis.

  View details for DOI 10.1084/jem.20101974

  View details for Web of Science ID 000306174300008

  View details for PubMedID 22734047

  View details for PubMedCentralID PMC3405500

• Identification of Naturally Occurring Fatty Acids of the Myelin Sheath That Resolve Neuroinflammation SCIENCE TRANSLATIONAL MEDICINE Ho, P. P., Kanter, J. L., Johnson, A. M., Srinagesh, H. K., Chang, E., Purdy, T. M., Van Haren, K., Wikoff, W. R., Kind, T., Khademi, M., Matloff, L. Y., Narayana, S., Hur, E. M., Lindstrom, T. M., He, Z., Fiehn, O., Olsson, T., Han, X., Han, M. H., Steinman, L., Robinson, W. H. 2012; 4 (137)

  Abstract

  Lipids constitute 70% of the myelin sheath, and autoantibodies against lipids may contribute to the demyelination that characterizes multiple sclerosis (MS). We used lipid antigen microarrays and lipid mass spectrometry to identify bona fide lipid targets of the autoimmune response in MS brain, and an animal model of MS to explore the role of the identified lipids in autoimmune demyelination. We found that autoantibodies in MS target a phosphate group in phosphatidylserine and oxidized phosphatidylcholine derivatives. Administration of these lipids ameliorated experimental autoimmune encephalomyelitis by suppressing activation and inducing apoptosis of autoreactive T cells, effects mediated by the lipids' saturated fatty acid side chains. Thus, phospholipids represent a natural anti-inflammatory class of compounds that have potential as therapeutics for MS.

  View details for DOI 10.1126/scitranslmed.3003831

  View details for Web of Science ID 000305075700005

  View details for PubMedID 22674551

  View details for PubMedCentralID PMC3953135

• Protective effect of an elastase inhibitor in a neuromyelitis optica-like disease driven by a peptide of myelin oligodendroglial glycoprotein MULTIPLE SCLEROSIS JOURNAL Herges, K., de Jong, B. A., Kolkowitz, I., Dunn, C., Mandelbaum, G., Ko, R. M., Maini, A., Han, M. H., Killestein, J., Polman, C., Goodyear, A. L., Dunn, J., Steinman, L., Axtell, R. C. 2012; 18 (4): 398-408

  Abstract

  The pathology of neuromyelitis optica (NMO), in contrast to multiple sclerosis, comprises granulocyte infiltrates along extensive lengths of spinal cord, as well as optic nerve. Furthermore, IFN-β treatment worsens NMO. We recently found that experimental autoimmune encephalomyelitis (EAE) induced with Th17 cells is exacerbated by IFN-β, in contrast to disease induced with Th1 where treatment attenuated symptoms.This study demonstrates the similarities between NMO and Th17 EAE and how neutrophils mediate pathology in Th17 disease.Levels of blood biomarkers in NMO were assessed by Luminex and ELISA. Effects of IFN-β on neutrophils were assessed by culture assays and immunofluorescence. EAE was induced by transfer of myelin-specific Th1 or Th17 cells and treated with Sivelestat sodium hydrate, a neutrophil elastase inhibitor.We show Th17 cytokines, granulocyte chemokines, type 1 interferon and neutrophil elastase are elevated in patients with definitive NMO. In culture, we find that IFN-β stimulates neutrophils to release neutrophil elastase. In Th17 EAE, we demonstrate neutrophilic infiltration in the optic nerve and spinal cord which was not present in Th1 EAE. Blockade of neutrophil elastase with Sivelestat had efficacy in Th17 EAE but not Th1 EAE.The similarities between Th17 EAE and NMO indicate that this model represents several aspects of NMO. Neutrophils are critical in the pathologies of both Th17-EAE and NMO, and therefore blockade of neutrophil elastase is a promising target in treating NMO.

  View details for DOI 10.1177/1352458512440060

  View details for Web of Science ID 000302289900006

  View details for PubMedID 22343184

  View details for PubMedCentralID PMC3319834

• Impaired neurosteroid synthesis in multiple sclerosis BRAIN Noorbakhsh, F., Ellestad, K. K., Maingat, F., Warren, K. G., Han, M. H., Steinman, L., Baker, G. B., Power, C. 2011; 134: 2703-2721

  Abstract

  High-throughput technologies have led to advances in the recognition of disease pathways and their underlying mechanisms. To investigate the impact of micro-RNAs on the disease process in multiple sclerosis, a prototypic inflammatory neurological disorder, we examined cerebral white matter from patients with or without the disease by micro-RNA profiling, together with confirmatory reverse transcription-polymerase chain reaction analysis, immunoblotting and gas chromatography-mass spectrometry. These observations were verified using the in vivo multiple sclerosis model, experimental autoimmune encephalomyelitis. Brains of patients with or without multiple sclerosis demonstrated differential expression of multiple micro-RNAs, but expression of three neurosteroid synthesis enzyme-specific micro-RNAs (miR-338, miR-155 and miR-491) showed a bias towards induction in patients with multiple sclerosis (P < 0.05). Analysis of the neurosteroidogenic pathways targeted by micro-RNAs revealed suppression of enzyme transcript and protein levels in the white matter of patients with multiple sclerosis (P < 0.05). This was confirmed by firefly/Renilla luciferase micro-RNA target knockdown experiments (P < 0.05) and detection of specific micro-RNAs by in situ hybridization in the brains of patients with or without multiple sclerosis. Levels of important neurosteroids, including allopregnanolone, were suppressed in the white matter of patients with multiple sclerosis (P < 0.05). Induction of the murine micro-RNAs, miR-338 and miR-155, accompanied by diminished expression of neurosteroidogenic enzymes and allopregnanolone, was also observed in the brains of mice with experimental autoimmune encephalomyelitis (P < 0.05). Allopregnanolone treatment of the experimental autoimmune encephalomyelitis mouse model limited the associated neuropathology, including neuroinflammation, myelin and axonal injury and reduced neurobehavioral deficits (P < 0.05). These multi-platform studies point to impaired neurosteroidogenesis in both multiple sclerosis and experimental autoimmune encephalomyelitis. The findings also indicate that allopregnanolone and perhaps other neurosteroid-like compounds might represent potential biomarkers or therapies for multiple sclerosis.

  View details for DOI 10.1093/brain/awr200

  View details for Web of Science ID 000294959800025

  View details for PubMedID 21908875

• T helper type 1 and 17 cells determine efficacy of interferon-beta in multiple sclerosis and experimental encephalomyelitis NATURE MEDICINE Axtell, R. C., de Jong, B. A., Boniface, K., Van der Voort, L. F., Bhat, R., De Sarno, P., Naves, R., Han, M., Zhong, F., Castellanos, J. G., Mair, R., Christakos, A., Kolkowitz, I., Katz, L., Killestein, J., Polman, C. H., Malefyt, R. d., Steinman, L., Raman, C. 2010; 16 (4): 406-U21

  Abstract

  Interferon-beta (IFN-beta) is the major treatment for multiple sclerosis. However, this treatment is not always effective. Here we have found congruence in outcome between responses to IFN-beta in experimental autoimmune encephalomyelitis (EAE) and relapsing-remitting multiple sclerosis (RRMS). IFN-beta was effective in reducing EAE symptoms induced by T helper type 1 (T(H)1) cells but exacerbated disease induced by T(H)17 cells. Effective treatment in T(H)1-induced EAE correlated with increased interleukin-10 (IL-10) production by splenocytes. In T(H)17-induced disease, the amount of IL-10 was unaltered by treatment, although, unexpectedly, IFN-beta treatment still reduced IL-17 production without benefit. Both inhibition of IL-17 and induction of IL-10 depended on IFN-gamma. In the absence of IFN-gamma signaling, IFN-beta therapy was ineffective in EAE. In RRMS patients, IFN-beta nonresponders had higher IL-17F concentrations in serum compared to responders. Nonresponders had worse disease with more steroid usage and more relapses than did responders. Hence, IFN-beta is proinflammatory in T(H)17-induced EAE. Moreover, a high IL-17F concentration in the serum of people with RRMS is associated with nonresponsiveness to therapy with IFN-beta.

  View details for DOI 10.1038/nm.2110

  View details for Web of Science ID 000276446800044

  View details for PubMedID 20348925

  View details for PubMedCentralID PMC3042885

• Blocking angiotensin-converting enzyme induces potent regulatory T cells and modulates TH1-and TH17-mediated autoimmunity PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Platten, M., Youssef, S., Hur, E. M., Ho, P. P., Han, M. H., Lanz, T. V., Phillips, L. K., Goldstein, M. J., Bhat, R., Raine, C. S., Sobel, R. A., Steinman, L. 2009; 106 (35): 14948-14953

  Abstract

  The renin-angiotensin-aldosterone system (RAAS) is a major regulator of blood pressure. The octapeptide angiotensin II (AII) is proteolytically processed from the decapeptide AI by angiotensin-converting enzyme (ACE), and then acts via angiotensin type 1 and type 2 receptors (AT1R and AT2R). Inhibitors of ACE and antagonists of the AT1R are used in the treatment of hypertension, myocardial infarction, and stroke. We now show that the RAAS also plays a major role in autoimmunity, exemplified by multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). Using proteomics, we observed that RAAS is up-regulated in brain lesions of MS. AT1R was induced in myelin-specific CD4+ T cells and monocytes during autoimmune neuroinflammation. Blocking AII production with ACE inhibitors or inhibiting AII signaling with AT1R blockers suppressed autoreactive TH1 and TH17 cells and promoted antigen-specific CD4+FoxP3+ regulatory T cells (Treg cells) with inhibition of the canonical NF-kappaB1 transcription factor complex and activation of the alternative NF-kappaB2 pathway. Treatment with ACE inhibitors induces abundant CD4+FoxP3+ T cells with sufficient potency to reverse paralytic EAE. Modulation of the RAAS with inexpensive, safe pharmaceuticals used by millions worldwide is an attractive therapeutic strategy for application to human autoimmune diseases.

  View details for DOI 10.1073/pnas.0903958106

  View details for Web of Science ID 000269481000040

  View details for PubMedID 19706421

  View details for PubMedCentralID PMC2736463

• Activation of kinin receptor B1 limits encephalitogenic T lymphocyte recruitment to the central nervous system NATURE MEDICINE Schulze-Topphoff, U., Prat, A., Prozorovski, T., Siffrin, V., Paterka, M., Herz, J., Bendix, I., Ifergan, I., Schadock, I., Mori, M. A., van Horssen, J., Schroetter, F., Smorodchenko, A., Han, M. H., Bader, M., Steinman, L., Aktas, O., Zipp, F. 2009; 15 (7): 788-793

  Abstract

  Previous proteomic and transcriptional analyses of multiple sclerosis lesions revealed modulation of the renin-angiotensin and the opposing kallikrein-kinin pathways. Here we identify kinin receptor B1 (Bdkrb1) as a specific modulator of immune cell entry into the central nervous system (CNS). We demonstrate that the Bdkrb1 agonist R838 (Sar-[D-Phe]des-Arg(9)-bradykinin) markedly decreases the clinical symptoms of experimental autoimmune encephalomyelitis (EAE) in SJL mice, whereas the Bdkrb1 antagonist R715 (Ac-Lys-[D-betaNal(7), Ile(8)]des-Arg(9)-bradykinin) resulted in earlier onset and greater severity of the disease. Bdkrb1-deficient (Bdkrb1(-/-)) C57BL/6 mice immunized with a myelin oligodendrocyte glycoprotein fragment, MOG(35-55), showed more severe disease with enhanced CNS-immune cell infiltration. The same held true for mixed bone marrow-chimeric mice reconstituted with Bdkrb1(-/-) T lymphocytes, which showed enhanced T helper type 17 (T(H)17) cell invasion into the CNS. Pharmacological modulation of Bdkrb1 revealed that in vitro migration of human T(H)17 lymphocytes across blood-brain barrier endothelium is regulated by this receptor. Taken together, these results suggest that the kallikrein-kinin system is involved in the regulation of CNS inflammation, limiting encephalitogenic T lymphocyte infiltration into the CNS, and provide evidence that Bdkrb1 could be a new target for the treatment of chronic inflammatory diseases such as multiple sclerosis.

  View details for DOI 10.1038/nm.1980

  View details for Web of Science ID 000267806900032

  View details for PubMedID 19561616

• Systems biology for identification of molecular networks in multiple sclerosis MULTIPLE SCLEROSIS Han, M. H., Steinman, L. 2009; 15 (5): 529-530

  View details for DOI 10.1177/1352458509103318

  View details for Web of Science ID 000265513400001

  View details for PubMedID 19389747

• Proteomic analysis of active multiple sclerosis lesions reveals therapeutic targets NATURE Han, M. H., Hwang, S., Roy, D. B., Lundgren, D. H., Price, J. V., Ousman, S. S., Fernald, G. H., Gerlitz, B., Robinson, W. H., Baranzini, S. E., Grinnell, B. W., Raine, C. S., Sobel, R. A., Han, D. K., Steinman, L. 2008; 451 (7182): 1076-U2

  Abstract

  Understanding the neuropathology of multiple sclerosis (MS) is essential for improved therapies. Therefore, identification of targets specific to pathological types of MS may have therapeutic benefits. Here we identify, by laser-capture microdissection and proteomics, proteins unique to three major types of MS lesions: acute plaque, chronic active plaque and chronic plaque. Comparative proteomic profiles identified tissue factor and protein C inhibitor within chronic active plaque samples, suggesting dysregulation of molecules associated with coagulation. In vivo administration of hirudin or recombinant activated protein C reduced disease severity in experimental autoimmune encephalomyelitis and suppressed Th1 and Th17 cytokines in astrocytes and immune cells. Administration of mutant forms of recombinant activated protein C showed that both its anticoagulant and its signalling functions were essential for optimal amelioration of experimental autoimmune encephalomyelitis. A proteomic approach illuminated potential therapeutic targets selective for specific pathological stages of MS and implicated participation of the coagulation cascade.

  View details for DOI 10.1038/nature06559

  View details for Web of Science ID 000253453600035

  View details for PubMedID 18278032

• Neurologic aspects of infections in international travelers NEUROLOGIST Han, M. H., Zunt, J. R. 2005; 11 (1): 30-44

  Abstract

  As international travel for business and pleasure becomes part of contemporary lifestyle, the clinician today is confronted with an increasing number of travelers returning ill with unfamiliar syndromes. The physician will encounter a myriad of patients with exotic infections, emerging infectious diseases, or resurgent Old-World infections.This review article will discuss salient points of important infectious diseases associated with overseas travel, provide a syndromic approach to the traveler who returns with neurologic manifestations, and list resources for additional diagnostic, therapeutic, and preventive information.As many of infections acquired in other countries can directly or indirectly affect the nervous system, the care of the ill traveler often falls into the hands of neurologists. The contemporary neurologist should therefore be knowledgeable of the clinical manifestations, potential complications, and appropriate management of region-specific infections.

  View details for DOI 10.1097/01.nrl.0000149972.87731.0f

  View details for Web of Science ID 000226265500004

  View details for PubMedID 15631642

• Effects of protein kinase CK2, extracellular signal-regulated kinase 2, and protein phosphatase 2A on a phosphatidic acid-preferring phospholipase A1 JOURNAL OF BIOLOGICAL CHEMISTRY Han, M. H., Han, D. K., Aebersold, R. H., Glomset, J. A. 2001; 276 (29): 27698-27708

  Abstract

  A soluble, phosphatidic acid-preferring phospholipase A1, expressed in mature bovine testes but not in newborn calf testes, may contribute to the formation or function of sperm. Here we incubated a recombinant preparation of the phospholipase in vitro with several enzymes including protein kinase CK2 (CK2), extracellular signal-regulated kinase 2 (ERK2), and protein phosphatase 2A (PP2A) to identify effects that might be of regulatory importance in vivo. Major findings were that 1) CK2 phosphorylated the phospholipase on serines 93, 105, and 716; 2) ERK2 phosphorylated the enzyme on serine 730; 3) there was cross-antagonism between the reactions that phosphorylated serines 716 and 730; 4) PP2A selectively hydrolyzed phosphate groups that were esterified to serines 716 and 730; 5) CK2alpha formed a stable, MgATP/MgGTP-dependent complex with the phospholipase by a novel mechanism; and 6) the complex showed reduced phospholipase activity and resembled a complex identified in homogenates of macaque testis. These results provide the first available information about the effects of reactions of phosphorylation and dephosphorylation on the behavior of the phospholipase, shed light on properties of CK2alpha that may be required for the formation of complexes with its substrates, and raise the possibility that a complex containing CK2alpha and the phospholipase may play a special biological role in the testis.

  View details for Web of Science ID 000169966900127

  View details for PubMedID 11328814

• Cloning of a phosphatidic acid-preferring phospholipase A(1) from bovine testis JOURNAL OF BIOLOGICAL CHEMISTRY Higgs, H. N., Han, M. H., Johnson, G. E., Glomset, J. A. 1998; 273 (10): 5468-5477

  Abstract

  We report the molecular cloning and expression of a phosphatidic acid-preferring phospholipase A1 from bovine testis. The open reading frame encoded an 875-amino acid protein with a calculated molecular mass of 97,576 daltons and a pI of 5.61. The sequence included a region similar to a lipase consensus sequence containing the putative active site serine and also included a potential, coiled-coil-forming region. Expression of the open reading frame in COS1 cells resulted in a 20-44-fold increase in phosphatidic acid phospholipase A1 activity over that of control cells. Mutation of the putative active site serine (amino acid 540) demonstrated that it was essential for this increase in enzyme activity. Northern blot analysis revealed at least five different messages with the highest overall message levels in mature testis, but detectable message in all tissues examined. Two possible alternately spliced regions in the open reading frame also were identified. Finally, a search of the data base identified six related proteins: a potential counterpart of the phospholipase A1 in Caenorhabditis elegans, two putative lipases in yeast, and three proteins separately encoded by the Drosophila retinal degeneration B gene and its mouse and human homologues.

  View details for Web of Science ID 000072345000012

  View details for PubMedID 9488669