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Our research focuses on the formation and destruction of a cellular structure called "myelin", which function is crucial for fast nerve conduction and survival of neurons. Breakdown of myelin, or demyelination is a common pathological feature found in many neurodegenerative diseases including multiple sclerosis and peripheral neuropathies, as well as traumatic brain injury. Our long-term research goal is to understand molecular mechanisms underlying demyelination associated with human diseases.
Current Research Projects
1. Traumatic Brain Injury (TBI): Chronic white matter atrophy or degeneration of myelinated axons is a common occurrence after repeated concussive injury, or mild TBI, which contributes to long-term functional deficits in the patients. This project focuses on elucidating the molecular mechanisms that contribute to myelin loss associated with mTBI. In collaboration with Dr. Bryan Pfister at NJIT, we are currently testing the hypothesis that mechanical injury disrupts normal axon-to-oligodendrocyte signaling necessary for maintaining myelin homeostasis in the brain. We use both in vitro myelinated axon stretch injury model and in vivo rodent mTBI models to elucidate the signaling mechanism associated with the myelin loss.
2. Charcot-Marie-Tooth (CMT) disease is the most common inherited demyelinating disorder affecting the peripheral nervous system (PNS). CMT4B is caused by loss-of-function mutations in a gene coding for Mtmr2, a phosphatase that is involved in phosphoinositide biosynthesis. Patients with CMT4B exhibit myelin abnormalities including demyelination as well as myelin overproduction. Functions of Mtmr2 and the lipid product PI(3,5)P2 have been implicated in regulating endo-lysosome trafficking and lysosome associated mTOR activity. Currently, we are investigating the intracellular signaling function of Mtmr2 in regulating myelin homeostasis in the PNS.
3. Stemness of Schwann cell: Repair in the peripheral nervous system (PNS) depends upon the plasticity of the myelinating cells, Schwann cells, and their ability to dedifferentiate, direct axonal regrowth, re-myelinate and allow functional recovery. The ability of such an exquisitely specialized myelinating cell to revert to an immature de-differentiated cell that can direct repair is remarkable, making Schwann cells one of the very few regenerative cell types in our bodies. Recent studies have shown the involvement of MAPK pathways in regulating the process. We use both in vitro and in vivo modes of peripheral nerve injury to investigate the mechanism of Schwann cell response to injury, i.e., its reversion to the immature state.
4. Developmental Myelination: One of the key molecules that regulate myelin formation in the PNS is neuregulin, an axonal protein that binds and activates erbB2/4 receptor complex on the Schwann cells. The receptors then activates various downstream signaling pathways that cooperate with signaling from extracellular matrix and other domains of Schwann cells to induce arrays of transcription factors that initiate the morphogenic process of myelin formation. Our lab is currently investigating modulators of neuregulin signal and the downstream effectors in regulating myelin formation.
21:120:355 Cell Biology
26:120:524 Cell, Molecular and Developmental Biology
26:120:526 Topics in Cell Biology: Signal Transduction
B.S. in Horticulture, Seoul National University, 1988.
M.S. in Biology, University of Toledo, 1990.
Ph.D. in Cell Biology, Neurobiology and Anatomy, University of Cincinnati, 1996.
Post-doc, Dana-Farber Cancer Institute, Harvard Medical School, 1997-2003.
Basak, S., Desai, D.J., Rho, E.H., Ramos, R., Maurel, P., and Kim, H.A. E-cadherin enhances neuregulin signaling and promotes Schwann cell myelination. Glia 2015 63:1522-1536.
Kim, H.A., Mindos, T., and D.B. Parkinson. Plastic Fantastic: Schwann cells and repair of the peripheral nervous system. Stem Cells Translational Medicine 2013
Yang, D.P., Kim, J., Syed, N., Tung, Y.J., Bhaskaran, A., Mindos, T., Mirsky, R., Jessen, K.R., Maurel, P., Parkinson, D.B., and H. A. Kim. p38 MAPK activation promotes denervated Schwann cell phenotype and functions as a negative regulator of Schwann cell differentiation and myelination. Journal of Neuroscience 2012 32 (21): 7158-7168.
Chen, Y., Wang, H., Yoon, S.O., Xu, X., Hottiger, M.O., Svaren, J., Nave, K.A., Kim, H.A., Olson, E.N., and Q.R. Lu. HDAC-mediated deacetylation of NF-κB is critical for Schwann cell myelination. Nature Neuroscience 2011 14 (4): 437-441.
Syed, N. and H. A. Kim. Soluble neuregulin and Schwann cell myelination: a therapeutic potential for improving remyelination of adult axons. Molecular and Cellular Pharmacology 2010 2 (4): 161-167.
Syed, N., K. Reddy, D. P. Yang, C. Taveggia, J. L. Salzer, P. Maurel, and H. A. Kim. Soluble neuregulin-1 has bi-functional, concentration-dependent effects on Schwann cell myelination Journal of Neuroscience 2010 30: 6122-6131.
Monnerie, H., Tang-Schomer, M.D., Iwata, A., Smith, D.H., Kim, H.A., and P.D. Le Roux. Dendritic alterations after dynamic axonal stretch injury in vitro. Experimental Neurology 2010 224: 415-423.
Kim, H. A. and P. Maurel. Primary Schwann cell cultures from rodents. In Doering, LC (ed) Protocols for Neural Cell Culture, 4th edition, Humana Press, New York, 2009, 253-268.
Tyler, W.A., Gangoli, N., Gokina, P., H. A. Kim, M. Covey, S. Levison and T. L. Wood. Differentiation of oligodendrocytes requires activation of mammalian target of rapamycin signaling. Journal of Neuroscience 2009 29 (19): p. 6367-6378.
Crawford, A., D. Desai, P. Gokina and H. A. Kim. E-cadherin expression in postnatal Schwann cell is induced by activation of cAMP-dependent protein kinase A pathway. Glia 2008 56:1637-1647.
Yang, D. P., D. P. Zhang, K. S. Mak, D. E.Bonder, S. L. Pomeroy and H. A. Kim. Schwann cell proliferation during Wallerian degeneration is not necessary for regeneration and remyelination of the peripheral nerves: axon-dependent removal of newly generated Schwann cells by apoptosis. Molecular and Cellular Neuroscience 2008 38(1): p. 80-88.
Ratner, N., J. Williams, J. J. Kordich and H. A. Kim. Schwann cell preparation from single mouse embryos: Analysis of neurofibromin function in Schwann cells. Methods in Enzymology 2006 407: p 22-33.
Guertin, A., Zang, P. D., Mak, K. S., Alberta, J. A. and H. A. Kim. Microanatomy of axon/glial signaling resolved in artificial sciatic nerves. Journal of Neuroscience 2005 25: p. 3478-3487.
Gray. P. A., H. Fu, P. Luo, Q. Zhao, J. Yu, A. Ferrari, T. Tenzen, D. Yuk, E. Tsung, Z. Cai, J. A. Alberta, L. Cheng, Y. Liu, J. M. Stenman, M. T. Valerius, N. Billings, H. A. Kim, A. P. McMahon, D. H. Rowitch, C. D. Stiles, and Q. Ma. Mouse Brain Organization Revealed through Direct Genome-scale TF expression analysis. Science 2004. 306 (5705): p. 2255-7.
Kim, H. A., N. Ratner, T. M. Roberts, and C. D. Stiles. Schwann cell proliferative responses to cAMP and Nf1 are mediated by cyclin D1. Journal of Neuroscience 2001. 21(4): p. 1110-6.
Kim, H. A., S. L. Pomeroy, W. Whoriskey, I. Pawlitzky, L. I. Benowitz, P. Sicinski, C. D. Stiles, and T. M. Roberts. A developmentally regulated switch directs regenerative growth of Schwann cells through cyclin D1. Neuron 2000. 26(2): p. 405-16.
Rosenbaum, T., H. A. Kim, Y. L. Boissy, B. Ling, and N. Ratner. Neurofibromin, the neurofibromatosis type 1 Ras-GAP, is required for appropriate P0 expression and myelination. Annals of the New York Academy of Sciences 1999. 883: p. 203-14.
Kim H. A., and N. A. Ratner. Procedure for isolating Schwann cells developed for analysis of the mouse embryonic lethal mutation NF1. Cell Biology and Pathology of Myelin: Evolving Biological Concepts and Therapeutic Approaches eds. Devon RM, Doucette R, Juurlink BHJ, Nazarali AJ, Schreyer DJ, and Verge VMK. Plenum press, New York, 1997, p 201-212.
Rosenbaum, C., S. Karyala, M. A. Marchionni, H. A. Kim, A. L. Krasnoselsky, B. Happel, I. Isaacs, R. Brackenbury, and N. Ratner. Schwann cells express NDF and SMDF/n-ARIA mRNAs, secrete neuregulin, and show constitutive activation of erbB3 receptors: evidence for a neuregulin autocrine loop. Experimental Neurology 1997. 148(2): p. 604-15.
Kim, H. A., B. Ling, and N. Ratner. Nf1-deficient mouse Schwann cells are angiogenic and invasive and can be induced to hyperproliferate: reversion of some phenotypes by an inhibitor of farnesyl protein transferase. Molecular & Cellular Biology 1997. 17(2): p. 862-72.
Kim, H. A., J. E. DeClue, and N. Ratner. cAMP-dependent protein kinase A is required for Schwann cell growth: interactions between the cAMP and neuregulin/tyrosine kinase pathways. Journal of Neuroscience Research 1997. 49(2): p. 236-47.
Wrabetz, L., M. L. Feltri, H. Kim, M. Daston, J. Kamholz, S. S. Scherer, and N. Ratner. Regulation of neurofibromin expression in rat sciatic nerve and cultured Schwann cells. Glia 1995. 15(1): p. 22-32.
Kim, H. A., T. Rosenbaum, M. A. Marchionni, N. Ratner, and J. E. DeClue. Schwann cells from neurofibromin deficient mice exhibit activation of p21ras, inhibition of cell proliferation and morphological changes. Oncogene 1995. 11(2): p. 325-35.