Browsing by Author "Kim, Hanna"

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    Calcineurin determines toxic versus beneficial responses to alpha-synuclein
    (National Academy of the Sciences, 2014) Caraveo, Gabriela; Auluck, Pavan K.; Whitesell, Luke; Chung, Chee Yeun; Baru, Valeriya; Mosharov, Eugene V.; Yan, Xiaohui; Ben-Johny, Manu; Soste, Martin; Picotti, Paola; Kim, Hanna; Caldwell, Kim A.; Caldwell, Guy A.; Sulzer, David; Yue, David T.; Lindquist, Susan; Massachusetts Institute of Technology (MIT); Whitehead Institute; Howard Hughes Medical Institute; Harvard University; Massachusetts General Hospital; Harvard Medical School; Columbia University; University of Alabama Tuscaloosa; Johns Hopkins University
    Calcineurin (CN) is a highly conserved Ca2+-calmodulin (CaM)dependent phosphatase that senses Ca2+ concentrations and transduces that information into cellular responses. Ca2+ homeostasis is disrupted by alpha-synuclein (alpha-syn), a small lipid binding protein whose misfolding and accumulation is a pathological hallmark of several neurodegenerative diseases. We report that alpha-syn, from yeast to neurons, leads to sustained highly elevated levels of cytoplasmic Ca2+, thereby activating a CaM-CN cascade that engages substrates that result in toxicity. Surprisingly, complete inhibition of CN also results in toxicity. Limiting the availability of CaM shifts CN's spectrum of substrates toward protective pathways. Modulating CN or CN's substrates with highly selective genetic and pharmacological tools (FK506) does the same. FK506 crosses the blood brain barrier, is well tolerated in humans, and is active in neurons and glia. Thus, a tunable response to CN, which has been conserved for a billion years, can be targeted to rebalance the phosphatase's activities from toxic toward beneficial substrates. These findings have immediate therapeutic implications for synucleinopathies.
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    Cyclized NDGA modifies dynamic alpha-synuclein monomers preventing aggregation and toxicity
    (Nature Portfolio, 2019) Daniels, Malcolm J.; Nourse, J. Brucker, Jr.; Kim, Hanna; Sainati, Valerio; Schiavina, Marco; Murrali, Maria Grazia; Pan, Buyan; Ferrie, John J.; Haney, Conor M.; Moons, Rani; Gould, Neal S.; Natalello, Antonino; Grandori, Rita; Sobott, Frank; Petersson, E. James; Rhoades, Elizabeth; Pierattelli, Roberta; Felli, Isabella; Uversky, Vladimir N.; Caldwell, Kim A.; Caldwell, Guy A.; Krol, Edward S.; Ischiropoulos, Harry; University of Pennsylvania; Pennsylvania Medicine; University of Alabama Tuscaloosa; University of Florence; University of Antwerp; Childrens Hospital of Philadelphia; University of Milano-Bicocca; University of Leeds; University of South Florida; Russian Academy of Sciences; University of Saskatchewan
    Growing evidence implicates alpha-synuclein aggregation as a key driver of neurodegeneration in Parkinson's disease (PD) and other neurodegenerative disorders. Herein, the molecular and structural mechanisms of inhibiting alpha-synuclein aggregation by novel analogs of nordihydroguaiaretic acid (NDGA), a phenolic dibenzenediol lignan, were explored using an array of biochemical and biophysical methodologies. NDGA analogs induced modest, progressive compaction of monomeric alpha-synuclein, preventing aggregation into amyloid-like fibrils. This conformational remodeling preserved the dynamic adoption of alpha-helical conformations, which are essential for physiological membrane interactions. Oxidation-dependent NDGA cyclization was required for the interaction with monomeric alpha-synuclein. NDGA analog-pretreated alpha-synuclein did not aggregate even without NDGA-analogs in the aggregation mixture. Strikingly, NDGA-pretreated alpha-synuclein suppressed aggregation of naive untreated aggregation-competent monomeric a-synuclein. Further, cyclized NDGA reduced alpha-synuclein-driven neurodegeneration in Caenorhabditis elegans. The cyclized NDGA analogs may serve as a platform for the development of small molecules that stabilize aggregation-resistant alpha-synuclein monomers without interfering with functional conformations yielding potential therapies for PD and related disorders.
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    Dopamine induces soluble alpha-synuclein oligomers and nigrostriatal degeneration
    (Nature Portfolio, 2017) Mor, Danielle E.; Tsika, Elpida; Mazzulli, Joseph R.; Gould, Neal S.; Kim, Hanna; Daniels, Malcolm J.; Doshi, Shachee; Gupta, Preetika; Grossman, Jennifer L.; Tan, Victor X.; Kalb, Robert G.; Caldwell, Kim A.; Caldwell, Guy A.; Wolfe, John H.; Ischiropoulos, Harry; University of Pennsylvania; Pennsylvania Medicine; Swiss Federal Institutes of Technology Domain; Ecole Polytechnique Federale de Lausanne; Northwestern University; Feinberg School of Medicine; Childrens Hospital of Philadelphia; University of Alabama Tuscaloosa; State University of New York (SUNY) Downstate Medical Center
    Parkinson's disease (PD) is defined by the loss of dopaminergic neurons in the substantia nigra and the formation of Lewy body inclusions containing aggregated alpha-synuclein. Efforts to explain dopamine neuron vulnerability are hindered by the lack of dopaminergic cell death in a-synuclein transgenic mice. To address this, we manipulated both dopamine levels and alpha-synuclein expression. Nigrally targeted expression of mutant tyrosine hydroxylase with enhanced catalytic activity increased dopamine levels without damaging neurons in non-transgenic mice. In contrast, raising dopamine levels in mice expressing human A53T mutant alpha-synuclein induced progressive nigrostriatal degeneration and reduced locomotion. Dopamine elevation in A53T mice increased levels of potentially toxic alpha-synuclein oligomers, resulting in conformationally and functionally modified species. Moreover, in genetically tractable Caenorhabditis elegans models, expression of alpha-synuclein mutated at the site of interaction with dopamine prevented dopamine-induced toxicity. These data suggest that a unique mechanism links two cardinal features of PD: dopaminergic cell death and alpha-synuclein aggregation.
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    Exposure to Green Tea Extract Alters the Incidence of Specific Cyclophosphamide-Induced Malformations
    (Wiley, 2012) Logsdon, Amanda L.; Herring, Betty J.; Lockard, Jarrett E.; Miller, Brittany M.; Kim, Hanna; Hood, Ronald D.; Bailey, Melissa M.; University of Alabama Tuscaloosa
    BACKGROUND Green tea extract (GTE) has been shown to have antioxidative properties due to its high content of polyphenols and catechin gallates. Previous studies indicated that catechin gallates scavenge free radicals and attenuate the effects of reactive oxygen species. Cyclophosphamide (CP) produces reactive oxidative species, which can have adverse effects on development, causing limb, digit, and cranial abnormalities. The current study was performed to determine if exposure to GTE can decrease teratogenic effects induced by CP in CD-1 mice. METHODS From gestation days (GD) 613, mated CD-1 mice were dosed with 400 or 800 mg/kg/d GTE; 100, 200, 400, or 800 mg/kg/d GTE + CP; CP alone, or the vehicle. GTE was given by gavage. CP (20 mg/kg) was given by intraperitoneal injection on GD 10. Dams were sacrificed on GD 17, and their litters were examined for adverse effects. RESULTS The highest GTE dose did not effectively attenuate, and in some cases exacerbated the negative effect of CP. GTE alone was also associated with an increased incidence of microblepharia. Conversely, moderate GTE doses (200 and/or 400 mg/kg/d) attenuated the effect of CP on fetal weight and (GTE 200 mg/kg/d) decreased the incidences of certain defects resulting from CP exposure. CONCLUSIONS Exposure of a developing mammal to moderate doses of GTE can modulate the effects of exposure to CP during development, possibly by affecting biotransformation, while a higher GTE dose tended to exacerbate the developmental toxicity of CP. GTE alone appeared to cause an adverse effect on eyelid development. Birth Defects Res (Part B) 95:195-201, 2012. (C) 2012 Wiley Periodicals, Inc.
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    Gene-by-environment interactions that disrupt mitochondrial homeostasis cause neurodegeneration in C. elegans Parkinson's models
    (Nature Portfolio, 2018) Kim, Hanna; Perentis, Rylee J.; Caldwell, Guy A.; Caldwell, Kim A.; University of Alabama Tuscaloosa; University of Alabama Birmingham
    Parkinson's disease (PD) is a complex multifactorial disorder where environmental factors interact with genetic susceptibility Accumulating evidence suggests that mitochondria have a central role in the progression of neurodegeneration in sporadic and/or genetic forms of PD We previously reported that exposure to a secondary metabolite from the soil bacterium, Streptomyces venezuelae, results in age and dose dependent dopaminergic (DA) neurodegeneration in Caenorhabditis elegans and human SH-SY5Y neurons Initial characterization of this environmental factor indicated that neurodegeneration occurs through a combination of oxidative stress, mitochondrial complex I impairment, and proteostatic disruption Here we present extended evidence to elucidate the interaction between this bacterial metabolite and mitochondrial dysfunction in the development of DA neurodegeneration We demonstrate that it causes a time dependent increase in mitochondrial fragmentation through concomitant changes in the gene expression of mitochondrial fission and fusion components In particular, the outer mitochondrial membrane fission and fusion genes, drp-1 (a dynamin related GTPase) and fzo-1 (a mitofusin homolog), are up and down regulated, respectively Additionally, eat-3, an inner mitochondrial membrane fusion component, an OPA1 homolog, is also down regulated These changes are associated with a metabolite induced decline in mitochondrial membrane potential and enhanced DA neurodegeneration that is dependent on PINK-1 function Genetic analysis also indicates an association between the cell death pathway and drp-1 following S ven exposure Metabolite induced neurotoxicity can be suppressed by DA neuron specific RNAi knockdown of eat-3 AMPK activation by 5-amino-4 imidazole carboxamide riboside (AICAR) ameliorated metabolite or PINK-1 induced neurotoxicity, however, it enhanced neurotoxicity under normal conditions These studies underscore the critical role of mitochondrial dynamics in DA neurodegeneration Moreover, given the largely undefined environmental components of PD etiology, these results highlight a response to an environmental factor that defines distinct mechanisms underlying a potential contributor to the progressive DA neurodegeneration observed in PD.
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    Investigation of Environmental and Genetic Risk Factors in the Development of Parkinson's Disease Utilizing the Model Organism Caenorhabditis Elegans
    (University of Alabama Libraries, 2018) Kim, Hanna
    One of the main features of Parkinson’s disease (PD) is the loss of nigrostriatal dopaminergic (DA) neurons in the presence of alpha-synuclein (-syn) inclusions known as Lewy Bodies. Over 90% of PD cases are sporadic while the remaining 5-10% have been associated with a genetic cause. It is thought that the environment, or a combination of environment and genetic factors, might lead to the loss of DA neurons in most sporadic PD cases. Increasing evidence suggests that mitochondrial dysfunction plays a central role in the development of DA neurodegeneration where both environmental and genetic contributors can be a source for mitochondrial dysfunction. Neurons are highly vulnerable to environmental and genetic factors that contribute to mitochondrial damage due to their high energy demands. Therefore, when these organelles are damaged, it can lead to disruption of mitochondrial homeostatic mechanisms, such as mitochondrial dynamics, autophagy, and cell death pathways, which can ultimately manifest as DA neurodegeneration. Using genetics and cell biology in Caenorhabditis elegans (C. elegans) as a PD animal model, we demonstrated mechanistic insights of gene by environmental interaction on mitochondrial homeostatic mechanisms in response to a bacterial secondary metabolite from a common soil bacteria, Streptomyces venezuelae (S. ven). We found that the S. ven metabolite disrupts protein homeostasis through impairment of the ubiquitin proteasome system, mitophagy alteration, and glutathione homeostasis interruption. Furthermore, metabolite exposure causes an imbalance in mitochondrial fission and fusion that results in mitochondrial fragmentation and mitochondrial DNA damage, leading to DA neurodegeneration. Acknowledging that not all DA neuronal vulnerability comes from environmental exposures, the role of a small GTPase, RAC1 (ced-10 in C. elegans), was investigated. This protein normally functions in cytoskeletal extension and the phagocytosis of dead cells or engulfment; here, it was found to maintain DA neurons in the presence of -syn in both C. elegans and human cell culture models. Specifically, a ced-10/Rac1 mutant, or depletion of ced-10 by RNAi, caused increase of -syn accumulation and DA neurodegeneration. Overexpression of ced-10/Rac1 reduced ced-10 depletion in C. elegans as well as in cell lines. Taken together, experimental findings with both gene backgrounds (Rac1/ced-10) and environmental exposures (S. ven) and provide insight into mechanisms underlying DA neuron cell death and the pathogenesis of PD.
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    Long-Term Exposure to [Cr3O(O2CCH2CH3)(6)(H2O)(3)](+) in Wistar Rats Fed Normal or High-Fat Diets Does Not Alter Glucose Metabolism
    (Humana Press, 2013) Herring, Betty J.; Logsdon, Amanda L.; Lockard, Jarrett E.; Miller, Brittany M.; Kim, Hanna; Calderon, Eric A.; Vincent, John B.; Bailey, Melissa M.; University of Alabama Tuscaloosa
    The essentiality of chromium(III) has been the subject of much debate, particularly in healthy subjects. Chromium(III)-containing supplements are widely used for body mass loss, building of lean muscle mass, and improving glucose and lipid metabolism. [Cr3O(O2CCH2CH3)(6)(H2O)(3)](+), Cr3, is one of the most-studied chromium nutritional supplements. The current study evaluates the effects of long-term (15 months) supplementation with Cr3 on body mass and glucose metabolism in Wistar rats on traditional and cafeteria-style (high fat, high carbohydrate) diets. Male Wistar rats were randomly assigned to one of four treatment groups: (1) control diet (milled Harlan Teklad LM-485 rodent diet), (2) control diet + 1 mg Cr3/kg body mass/day, (3) a cafeteria-style (CAF) diet (high fat, high carbohydrate), or (4) CAF diet + 1 mg Cr3/kg/day. Cr3 supplementation had no effect on fasting blood glucose levels or blood glucose levels in response to glucose and insulin challenges. Rats consuming the CAF + Cr3 diet tended to have a significantly higher body mass than rats consuming the CAF diet, but necropsy results showed no difference in visceral fat or body wall thickness between groups. These data suggest that long-term Cr3 supplementation does not significantly affect body mass in rats consuming a normal diet or glucose levels or metabolism in rats consuming either diet.
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    The Small GTPase RAC1/CED-10 Is Essential in Maintaining Dopaminergic Neuron Function and Survival Against alpha-Synuclein-Induced Toxicity
    (Springer, 2018) Kim, Hanna; Calatayud, Caries; Guha, Sanjib; Fernandez-Carasa, Irene; Berkowitz, Laura; Carballo-Carbajal, Iria; Ezquerra, Mario; Fernandez-Santiago, Ruben; Kapahi, Pankaj; Raya, Angel; Miranda-Vizuete, Antonio; Miguel Lizcano, Jose; Vila, Miquel; Caldwell, Kim A.; Caldwell, Guy A.; Consiglio, Antonella; Dalfo, Esther; University of Alabama Tuscaloosa; Institut d'Investigacio Biomedica de Bellvitge (IDIBELL); Bellvitge University Hospital; University of Barcelona; Hospital Duran i Reynals; Centro de Medicina Regenerativa de Barcelona; Buck Institute for Research on Aging; Autonomous University of Barcelona; Hospital Universitari Vall d'Hebron; Vall d'Hebron Institut de Recerca (VHIR); Hospital Clinic de Barcelona; IDIBAPS; ICREA; Consejo Superior de Investigaciones Cientificas (CSIC); University of Sevilla; CSIC-JA-USE - Instituto de Biomedicina de Sevilla (IBIS); Virgen del Rocio University Hospital; Universitat de Vic - Universitat Central de Catalunya (UVic-UCC)
    Parkinson's disease is associated with intracellular alpha-synuclein accumulation and ventral midbrain dopaminergic neuronal death in the Substantia Nigra of brain patients. The Rho GTPase pathway, mainly linking surface receptors to the organization of the actin and microtubule cytoskeletons, has been suggested to participate to Parkinson's disease pathogenesis. Nevertheless, its exact contribution remains obscure. To unveil the participation of the Rho GTPase family to the molecular pathogenesis of Parkinson's disease, we first used C elegans to demonstrate the role of the small GTPase RACI (ced-10 in the worm) in maintaining dopaminergic function and survival in the presence of alpha-synuclein. In addition, ced-10 mutant worms determined an increase of alpha-synuclein inclusions in comparison to control worms as well as an increase in autophagic vesicles. We then used a human neuroblastoma cells (M17) stably over-expressing alpha-synuclein and found that RAC1 function decreased the amount of amyloidogenic alpha-synuclein. Further, by using dopaminergic neurons derived firm patients of familial LRRIC2-Parkinson's disease we report that human RAC1 activity is essential in the regulation of dopaminergic cell death, alpha-synuclein accumulation, participates in neurite arborization and modulates autophagy. Thus, we determined for the first time that RAC1/ced-10 participates in Parkinson's disease associated pathogenesis and established RAC1/ced-10 as a new candidate for further investigation of Parkinson's disease associated mechanisms, mainly focused on dopaminergic function and survival against alpha-synuclein-induced toxicity.
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    The Small GTPase RAC1/CED-10 Is Essential in Maintaining Dopaminergic Neuron Function and Survival Against alpha-Synuclein-Induced Toxicity (vol 55, pg 7533, 2018)
    (Springer, 2018) Kim, Hanna; Calatayud, Carles; Guha, Sanjib; Fernandez-Carasa, Irene; Berkowitz, Laura; Carballo-Carbajal, Iria; Ezquerra, Mario; Fernandez-Santiago, Ruben; Kapahi, Pankaj; Raya, Angel; Miranda-Vizuete, Antonio; Miguel Lizcano, Jose; Vila, Miquel; Caldwell, Kim A.; Caldwell, Guy A.; Consiglio, Antonella; Dalfo, Esther; University of Alabama Tuscaloosa; Institut d'Investigacio Biomedica de Bellvitge (IDIBELL); Bellvitge University Hospital; University of Barcelona; Hospital Duran i Reynals; CIBER - Centro de Investigacion Biomedica en Red; CIBERBBN; Centro de Medicina Regenerativa de Barcelona; Buck Institute for Research on Aging; Hospital Clinic de Barcelona; IDIBAPS; ICREA; Consejo Superior de Investigaciones Cientificas (CSIC); University of Sevilla; CSIC-JA-USE - Instituto de Biomedicina de Sevilla (IBIS); Virgen del Rocio University Hospital; Autonomous University of Barcelona; Universitat de Vic - Universitat Central de Catalunya (UVic-UCC)
    With the author(s)' decision to opt for Open Choice the copyright of the article changed on March 2018 to A (c) The Author(s) 2018 and the name of one of the author was changed to "Sanjib Guha".
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    Therapeutic genetic variation revealed in diverse Hsp104 homologs
    (eLife Sciences Publications, 2020) March, Zachary M.; Sweeney, Katelyn; Kim, Hanna; Yan, Xiaohui; Castellano, Laura M.; Jackrel, Meredith E.; Lin, JiaBei; Chuang, Edward; Gomes, Edward; Willicott, Corey W.; Michalska, Karolina; Jedrzejczak, Robert P.; Joachimiak, Andrzej; Caldwell, Kim A.; Caldwell, Guy A.; Shalem, Ophir; Shorter, James; University of Pennsylvania; Pennsylvania Medicine; Childrens Hospital of Philadelphia; University of Alabama Tuscaloosa; United States Department of Energy (DOE); Argonne National Laboratory; University of Chicago; Washington University (WUSTL)
    The AAA+ protein disaggregase, Hsp104, increases fitness under stress by reversing stress-induced protein aggregation. Natural Hsp104 variants might exist with enhanced, selective activity against neurodegenerative disease substrates. However, natural Hsp104 variation remains largely unexplored. Here, we screened a cross-kingdom collection of Hsp104 homologs in yeast proteotoxicity models. Prokaryotic ClpG reduced TDP-43, FUS, and alpha-synuclein toxicity, whereas prokaryotic ClpB and hyperactive variants were ineffective. We uncovered therapeutic genetic variation among eukaryotic Hsp104 homologs that specifically antagonized TDP-43 condensation and toxicity in yeast and TDP-43 aggregation in human cells. We also uncovered distinct eukaryotic Hsp104 homologs that selectively antagonized alpha-synuclein condensation and toxicity in yeast and dopaminergic neurodegeneration in C. elegans. Surprisingly, this therapeutic variation did not manifest as enhanced disaggregase activity, but rather as increased passive inhibition of aggregation of specific substrates. By exploring natural tuning of this passive Hsp104 activity, we elucidated enhanced, substrate-specific agents that counter proteotoxicity underlying neurodegeneration.
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    TorsinA rescues ER-associated stress and locomotive defects in C. elegans models of ALS
    (Company of Biologists, 2014) Thompson, Michelle L.; Chen, Pan; Yan, Xiaohui; Kim, Hanna; Borom, Akeem R.; Roberts, Nathan B.; Caldwell, Kim A.; Caldwell, Guy A.; University of Alabama Tuscaloosa; University of Alabama Birmingham
    Molecular mechanisms underlying neurodegenerative diseases converge at the interface of pathways impacting cellular stress, protein homeostasis and aging. Targeting the intrinsic capacities of neuroprotective proteins to restore neuronal function and/or attenuate degeneration represents a potential means toward therapeutic intervention. The product of the human DYT1 gene, torsinA, is a member of the functionally diverse AAA+ family of proteins and exhibits robust molecular-chaperone-like activity, both in vitro and in vivo. Although mutations in DYT1 are associated with a rare form of heritable generalized dystonia, the native function of torsinA seems to be cytoprotective in maintaining the cellular threshold to endoplasmic reticulum (ER) stress. Here we explore the potential for torsinA to serve as a buffer to attenuate the cellular consequences of misfolded-protein stress as it pertains to the neurodegenerative disease amyotrophic lateral sclerosis (ALS). The selective vulnerability of motor neurons to degeneration in ALS mouse models harboring mutations in superoxide dismutase (SOD1) has been found to correlate with regional-specific ER stress in brains. Using Caenorhabditis elegans as a system to model ER stress, we generated transgenic nematodes overexpressing either wild-type or mutant human SOD1 to evaluate their relative impact on ER stress induction in vivo. These studies revealed a mutant-SOD1-specific increase in ER stress that was further exacerbated by changes in temperature, all of which was robustly attenuated by co-expression of torsinA. Moreover, through complementary behavioral analysis, torsinA was able to restore normal neuronal function in mutant G85R SOD1 animals. Furthermore, torsinA targeted mutant SOD1 for degradation via the proteasome, representing mechanistic insight on the activity that torsinA has on aggregate-prone proteins. These results expand our understanding of proteostatic mechanisms influencing neuronal dysfunction in ALS, while simultaneously highlighting the potential for torsinA as a novel target for therapeutic development.