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Y. Hwan Kim, PhD |
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| Project 1: Assessing regulatory roles of SUMOylation in DAT, alpha-synuclein, and LRRK2 in Parkinson's disease pathology: Post-translational modification (PTM) has been addressed as a key regulatory mechanism for modulating protein aggregation/degradation in neurodegeneration. However, a form of PTM, Small Ubiquitin-like Modifier (SUMO) has not been well characterized in Parkinson's disease (PD) pathology. Although SUMOylation may increase the solubility of alpha-synuclein, SUMOylated proteins including alpha-synuclein have been detected in the halo of Lewy bodies. Thus it is still unclear in understanding the role of SUMOylation in dopaminergic neurons. Here, we assess the role of SUMO conjugase, Ubc9 as a critical post-translational modifier to regulate the solubility, stability, and function of dopamine transporter (DAT), alpha-synuclein, and LRRK2 in dopaminergic neurons in vitro and in vivo. The objectives of this work is to elucidate the mechanisms of SUMOylation in preventing alpha-synuclein mediated protein aggregation and enhancing dopamine uptake via DAT and kinase activity from LRRK2 in dopaminergic neurons. This implies that pathological changes in the SUMOylation of DAT and/or alpha-synuclein may lead to alteration in dopamine reuptake and acute regulation of protein (mis)folding or aggregation, which is related to the neuropathology of PD. We identified that both DAT and alpha-synuclein are constitutively SUMOylated in mouse striatum and midbrain and observed that the overexpression of Ubc9 protects rat dopaminergic N27 cells against MPP+ induced oxidative stress. We also demonstrated that the inhibition of DAT degradation by Ubc9 was mediated by the inhibition of proteasome and lysosome (Cartier et al., 2019). Moreover, Ubc9-mediated SUMOylation increases the surface level of DAT in the plasma membrane and further its action enhances DAT functional expression in the plasma membrane, triggering an increase in dopamine uptake capacity. In the MPTP-lesioned mice, the chronic treatment substantially reduces the level of SUMO1 conjugated to alpha-synuclein in the mouse striatum. This suggests that pathological changes in the SUMOylation of DAT and alpha-synuclein result in significant alteration in dopamine clearance/recycling and protein (mis)folding or aggregation, respectively. Therefore, SUMOylation of DAT and alpha-synuclein can be potential therapeutic targets for neurological disorders such as ADHD, depression, and PD. | ||
| Project 2: Oxidative stress increases the levels of deSUMOylation in PD related proteins for inducing PD pathology: Since our preliminary data strongly suggest that MPTP-induced toxicity reduces the SUMO conjugation from -synuclein in the striatum, we are intrigued to assess the mechanisms of deSUMOylation by MPTP (MPP+)-mediated oxidative stress. Using collected mouse striatum and brainstem samples from MPTP or vehicle-treated tissues, we are measuring the levels of SUMO proteases (SENPs) conjugated to -synuclein. This approach will provide insight into the role of SUMOylation in protecting dopaminergic neurons from oxidative insults and verify a potential mechanism, underlying this neuroprotection. However, these studies will not tell us if deSUMOylation plays a role in PD pathology. There are at least 6 isoforms of SENPs that have been identified in mammalian cells and SUMO1 was detected in the halo of Lewy bodies (Kim et al., 2011). Since the level of deSUMOylation has never been reported in the PD brains, here we will turn our efforts to determine if the SUMO proteases (SENPs) levels are higher in the striatum and brainstem from human PD tissues than those in age-matched normal brains. We will measure the level of SENPs in human tissue samples from PD patients and controls to test the hypothesis that SENP levels and/or activities are stimulated with oxidative stress, which is part of pathological mechanism of PD. Our preliminary results demonstrated that MPTP-induced oxidative stress removed SUMO1 from -synuclein in mouse striatum and midbrain, while Ubc9 overexpression-mediated SUMOylation protects the dopaminergic neurons in the striatum and SN against MPTP toxicity (in preparation). Therefore, we are investigating whether the MPTP-induced SUMO1 removal from -synuclein in the mouse striatum is due to higher levels of SENPs in the MPTP-treated striatum and/or brainstem, compared to vehicle-treated tissues. We also expect to see that higher levels of SENPs in the Lewy bodies than those in normal brainstem tissues and to identify specific isoforms of SENPs from human PD brains. This approach will help us determine if stimulating SENPs is related to induce the PD pathology in the human and mouse brains. We anticipate that deSUMOylating enzymes, SENPs may be elevated in PD pathological processes. Therefore, this approach will help identify how deSUMOylation could be targeted for potentially preventing or slowing pathological progress. | ||
Project 3: Developing neuroprotective compounds as potential therapeutics in Parkinson's disease mouse models: Most available PD drugs are designed to alleviate the PD motor symptoms, however, they cause side-effects after long-term use. Thus we focus on identifying potential neuroprotective/recovery compounds to halt or slow the neuropathology, in addition to alleviate motor- and non-motor symptoms. In collaboration with AurimMed Pharma (Park City, Utah) and AptaBio Therapeutics (Kiheung, Korea), we focus on identifying novel small compounds to develop potential therapeutic drugs in Parkinson's disease. After our initial in vitro screening using cell viability (MTT) or cytotoxicity (LDH) assays, we narrowed a few target compounds for assessing neuro-recovery effects in the MPTP-lesioned or alpha-synuclein A53T mutant mouse models. Our recent mouse studies suggest that oral treatment of novel compounds for two weeks was sufficient to improve motor functions in behavioral tests such as pole, hindlimb clasping, cross-beam, rotarod, and open-field ambulatory mobility tests. Furthermore, we identified that the novel AurimMed compound provided the neuroprotective/recovery effects from the MPTP-induced deficits in the mouse brain. Our study will provide prerequisites for developing a therapeutic application and launching an Investigational New Drug study. Since those novel compounds are safe and orally administrable for penetrating the blood brain barrier, a few lead compounds can be quickly moved on to be tested in human subjects. The overall goal is to develop clinically safe, orally available anti-Parkinsonian drug candidates intended to significantly slow down the disease progression via the neuroprotective properties, in addition to relieving PD symptoms. |
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Project 4: Developing a combination therapy for reducing PD symptoms as well as providing neuroprotective effects: Levodopa (L-Dopa) replacement therapy remains the most common and effective treatment for PD, although it induces the complication of L-Dopa induced dyskinesia after years of use. Our group demonstrated that lithium has neuroprotective effects in a few Parkinson's disease (PD) in vitro and mouse models. We confirmed that the potential application of lithium in combination with L-Dopa/Carbidopa, not only reduces MPTP-induced abnormal involuntary movements (AIMs) but also protects against cell death in MPTP-lesioned mice (Lazzara et al., 2015). Here, we are developing a potential combination therapy of lithium with safe food ingredients such as curcumin and 7,8-Dihydroxyflavone (7,8-DHF) in nanoparticles for alleviating PD symptoms as well as providing neuroprotective effects in PD mouse models. This approach can be an excellent therapeutic option for neurodegenerative diseases due to low costs and low potential side-effects. The use of low dose of lithium in combination with other potential or pre-existing therapeutic compounds may be a promising approach for alleviating symptoms as well as providing neuroprotective effects to halt the disease progression in PD and other neurodegenerative diseases. |
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Project 5: Synergistic Damage of Commercially Available Environmental Toxins in Parkinson's Disease Models: Although several genetic mutations have been identified to cause Parkinson's disease (PD), the vast majority of cases are considered to be sporadic or multifactorial. Interestingly, epidemiological studies have shown that PD is more prevalent amongst farmers and rural populations. Thus, it has been suggested that exposure to pesticides and other environmental toxins may increase the risk of PD. In support of this notion, it has been shown that the herbicide, paraquat, and the fungicide, maneb, can cause motor deficits individually, as well as cause synergistic damage in mice when used together. We have tested commercially available pesticides for causing synergistic or additive damage in an in vitro PD model, when used together. After exposure of commercially-used pesticides such as acephate, alachlor, atrazine, diuron, 2-methyl-4-chlorophenoxyacetic acid (MCPA), and mecoprop, to rat dopaminergic N27 cells at varying concentrations and we measured cell viability using MTT assays. After identifying the non-toxic concentrations of single pesticide treatments, we measured the cell viability with the exposure of two different combinations of these pesticides. When tested individually, only high concentrations of diuron (14.4 and 28.8 µM) caused a significant decrease in cell viability. However, when we examined the effect of the combined pesticides at concentrations that did not show damage individually, we identified four combinations that cause synergistic loss, and five that cause additive loss in cell viability. Our results suggest that exposure to multiple combinations of pesticides may cause dopaminergic toxicity and further lead to sporadic PD pathology. Furthermore, we found that apoptosis was the mechanism of cell death in at least one of the pesticide combinations (Janezic et al., 2016). Our results can bring more public awareness to the detrimental effects of combined pesticide usage in PD pathology. Currently we are testing those synergistic toxicities of pesticide combinations in PD fly (collaboration with Lawal Lab) and mouse models. |
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| Current Lab members: Y. Hwan Kim, Ph.D. (Principal Investigator, Associate Professor) Post-doc: Dinesh Verma, Ph.D. Graduate: Lindsey Ruggiero (Neuroscience PhD) Anurupa Ghosh (Neuroscience PhD) Benedict Igwe (Neuroscience PhD) Undergraduate researchers: Alex Burris, Austin Jackson, Suhyun Nam, and Michelle Scott Lab Alumni: Etienne Cartier, Ph.D. (Post-doc), a senior researcher at UT Southwestern, TX Juan Viana (MS, Neuroscience): Research Associate at Aberdeen Research Lab, MD Dionne Williams (MS, Neuroscience): Neuroscience PhD candidate at DSU Carol Lazzara (MS, Neuroscience): Realtor, Lewes Beach, DE Eric Janezic (MS, Neuroscience): Ph.D. student at the University of Washington, Seattle, WA Janae Caviness (MS, Neuroscience): Cell culture scientist at UPenn Neuroscience Research Ct Sundus Ahmed (Undergrad researcher): Eurofins Lancaster Lab, West point, PA Thaddeus Lehman (Undergrad researcher): Researcher at Siemens, Milford, DE Sambee G Kanda (Undergrad researcher): Researcher at Christiana hospital, DE Margaret Steward (Undergrad researcher): Ph.D. student at the Ohio State University Xenia Davis (Undergrad researcher): Ph.D. student at the University of Cincinnati TaeHo Cho (Undergrad researcher): Ph.D. student at DGIST in S. Korea Cassio Noso (Undergrad researcher): Ph.D. student at Univ. of Sao Paolo in Brazil Nicole Brown (Undergrad researcher): Science teacher in DE Kinjal Patel (former lab manager). Former Undergraduate interns: Tahlia Casey (senior at DSU), Doug Mullen (MS student, Liberty Univ), Young Lee (U. Delaware), JT Lee (Applying med school), Katrina Mitchell (Preparing for med school), Joseph Katz (U. Delaware), Summer Stone (Wesley College), Alexis Neuer (DSU), and April Roeper (Wilmington Univ). Common Lab techniques: Western-blot, qRT-PCR, cell viability assays (MTT & LDH), ELISA, protein activity assays (including DAT,HAT & HDAC), microarray, Immunoprecipitation, immunohistochemistry, confocal microscopy, stereology, and Mass Spectrometry (collaboration). Education and Training (Y. Hwan Kim) |
1% of the population above the age of 65. The disorder is primarily characterized by the selective loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) in the midbrain and formation of intraneuronal inclusions called "Lewy bodies" which contain alpha-synuclein as their major protein component. The pathological mechanisms involved in neuropathology associated with PD is largely unknown, however, the A53T mutation of alpha-synuclein causes Lewy body formation and is a well-known genetic PD model.| Korea University, Seoul, S. Korea | BA | Plant Physiology/ Genetic Engineering |
| Korea University, Seoul, S. Korea | MS | Biotechnology |
| University of California, Los Angeles (UCLA) | PhD | Neuroscience |
| Johns Hopkins Medical Institution, Baltimore, MD | Post-Doctoral Fellow | Neuropathology in School of Medicine |
| Buck Institute for Research on Aging, Novato, CA | Sr. Post-Doc | Parkinson’s Disease |
Memberships and Awards (Hwan Kim): |
• Cartier E, Garcia-Olivares J, Janezic EM, Viana J, Moore M, Lin ML, Caplan JL, Torres G, and Kim YH. The SUMO conjugase Ubc9 delays the degradation of Dopamine Transporter, enhancing its cell surface level and dopamine uptake. Frontiers in Cellular Neuroscience. 2019 Feb 8, 13(35):1-23. • Chae KS and Kim YH. A potential role of geomagnetic field in transcranial magnetic stimulation therapy for neurodegenerative diseases. Frontiers in Human Neuroscience. 2017 Sep, 478(11):1-5. review • Janezic EM, Caviness J, Kanda GS, Davis XD, and Kim YH. Commercially available pesticides cause additive or synergistic damages in dopaminergic cells: Relevance for Parkinson's disease pathology. Annals of NeurodegenerPeerative disorders. 2016 1(2):1010:1-9. • Lazzara CL and Kim YH. Potential application of Lithium in Parkinson's and other neurodegenerative diseases. Frontiers in Neuroscience. 2015 Oct 27:9:403. review. • Lazzara CL, Riley RR, Rane A, Andersen JK and Kim YH. The combination of lithium and L-dopa/Carbidopa reduces MPTP-induced abnormal involuntary movements (AIMs) in mice: relevance for Parkinson's disease therapy. Brain Res. 2015 Jul, 1622:127-136. • Lieu C, Dewey C, Chinta S, Rane A, Rajagopolan S, Batir S, Kim YH, Andersen JK. Lithium prevents parkinsonian behavioral and striatal phenotypes in an aged parkin mutant transgenic mouse model. Brain Res. 2014 Dec, 27;1591:111-117. • Kim YH, Rane A, Lussier S, and Andersen JK. Lithium protects against oxidative stress-mediated cell death in alpha-synuclein over-expressing in vitro and in vivo models of Parkinson's disease. J. Neurosci Res. 2011 89(10):1666-75. • Kim YH, Lussier S, Rane A, Choi SW, and Andersen JK. Inducible dopaminergic glutathione depletion in an alpha-synuclein transgenic mouse model results in age-related olfactory dysfunction. Neuroscience 2011 13;172:379-86. • Satre D, Kim YH, and Corbitt C. Androgen receptor location in the Dark-eyed Junco using a probe for in situ hybridization histochemistry generated from zebra finch cDNA. J. Neuroscience Methods 2011 30;201(1):180-4. • Naurin S, Hansson B, Hasselquist D, Kim YH, and Bensch S. The sex-biased brain: sexual dimorphism in gene expression in two species of songbirds. BMC Genomics 2011 Jan; 14;12(1):37. • Itoh Y, Replogle K, Kim YH, Wade J, Clayton DF, and Arnold AP. Sex bias and dosage compensation in the zebra finch versus chicken genomes: general and specialized patterns among birds. Genome Research. 2010 20(4):512-8. • Dragich JM, Kim YH, Arnold AP, Schanen CN. Differential distribution of the Mecp2 splice variants in the postnatal mouse brain. J Comp Neurol. 2007 Feb 2;501(4):526-542. • Kim YH, Arnold AP. Expression of NGF and trkA mRNA in song control and other regions of the zebra finch brain. Neurosci. Lett. 2006 Dec 1;409(2):151-6. • Kim YH, Peregrine J, Arnold AP. The distribution of expression of doublecortin (DCX) mRNA and protein in zebra finch brain. Brain Research. 2006 Aug 23;1106(1):189-96. • Kim YH, Arnold AP. Distribution and onset of retinaldehyde dehydrogenase (zRalDH) expression in the zebra finch brain: lack of sex difference in HVC and RA at early posthatch ages. J. Neurobiol. 2005 Dec;65(3):260-268 • Kim YH, Perlman WR, Arnold AP. Expression of androgen receptor mRNA in the zebra finch song system: developmental regulation by estrogen. J Comp Neurol. 2004 Feb 16;469(4):535-47. • Cole AM, Tahk S, Oren A, Yoshioka D, Kim YH, Park A, Ganz T. Determinants of Staphylococcus aureus nasal carriage. Clin Diagn Lab Immunol. 2001 Nov;8(6):1064-9. • Cole AM, Kim YH, Tahk S, Hong T, Weis P, Waring AJ, Ganz T. Calcitermin, a novel antimicrobial peptide isolated from human airway secretions. FEBS Lett. 2001 Aug 24;504(1-2):5-10. • Cole AM, Shi J, Ceccarelli A, Kim YH, Park A, Ganz T. Inhibition of neutrophil elastase prevents cathelicidin activation and impairs clearance of bacteria from wounds. Blood. 2001 Jan 1;97(1):297-304. • Saldanha CJ, Tuerk MJ, Kim YH, Fernandes AO, Arnold AP, Schlinger BA. Distribution and regulation of telencephalic aromatase expression in the zebra finch revealed with a specific antibody. J Comp Neurol. 2000 Aug 7;423(4):619-30. • Cole AM, Wu M, Kim YH, Ganz T. Microanalysis of antimicrobial properties of human fluids. J Microbiol Methods. 2000 Jul;41(2):135-43. • Kim YH, Yang JW, Kim CW. Suspension culture of an antibacterial peptide producing cell line from Bombina orientalis. J Microbiol and Biotech. 1998 8(5):461-465. Summary of Center-Funded Research
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