Medicine and Health Sciences Commons^™

The Histone Deacetylase Inhibitor Tubacin Mitigates Endothelial Dysfunction By Up-Regulating The Expression Of Endothelial Nitric Oxide Synthase., Jihui Chen, Jian Zhang, Noor F. Shaik, Bing Yi, Xin Wei, Xiao-Feng Yang, Ulhas P. Naik, Ross Summer, Guijun Yan, Xinyun Xu, Jianxin Sun

Center for Translational Medicine Faculty Papers

Endothelial nitric oxide (NO) synthase (eNOS) plays a critical role in the maintenance of blood vessel homeostasis. Recent findings suggest that cytoskeletal dynamics play an essential role in regulating eNOS expression and activation. Here, we sought to test whether modulation of cytoskeletal dynamics through pharmacological regulation of histone deacetylase 6 (HDAC6)-mediated tubulin deacetylation affects eNOS expression and endothelial function in vitro and in vivo.Wefound that tubulin acetylation inducer (tubacin), a compound that appears to selectively inhibit HDAC6 activity, dramatically increased eNOS expression in several different endothelial cell lines, as determined by both immunoblotting and NO production assays. Mechanistically, we found …

Gasdermins In Apoptosis: New Players In An Old Game., Corey Rogers, Emad S. Alnemri

Department of Biochemistry and Molecular Biology Faculty Papers

Apoptosis is a form of programmed cell death (PCD) that plays critical physiological roles in removing superfluous or dangerous cell populations that are unneeded or threatening to the health of the host organism. Although the molecular pathways leading to activation of the apoptotic program have been extensively studied and characterized starting in the 1970s, new evidence suggests that members of the gasdermin superfamily are novel pore-forming proteins that augment apoptosis by permeabilizing the mitochondria and participate in the final stages of the apoptotic program by inducing secondary necrosis/pyroptosis. These findings may explain outstanding questions in the field such as why …

Allele-Specific Rna Interference Prevents Neuropathy In Charcot-Marie-Tooth Disease Type 2d Mouse Models., Kathryn H Morelli, Laurie B Griffin, Nettie K Pyne, Lindsay M Wallace, Allison M Fowler, Stephanie N Oprescu, Ryuichi Takase, Na Wei, Rebecca Meyer-Schuman, Dattatreya Mellacheruvu, Jacob O Kitzman, Samuel G Kocen, Timothy J Hines, Emily L Spaulding, James R Lupski, Alexey Nesvizhskii, Pedro Mancias, Ian J Butler, Xiang-Lei Yang, Ya-Ming Hou, Anthony Antonellis, Scott Q Harper, Robert W Burgess

Department of Biochemistry and Molecular Biology Faculty Papers

Gene therapy approaches are being deployed to treat recessive genetic disorders by restoring the expression of mutated genes. However, the feasibility of these approaches for dominantly inherited diseases - where treatment may require reduction in the expression of a toxic mutant protein resulting from a gain-of-function allele - is unclear. Here we show the efficacy of allele-specific RNAi as a potential therapy for Charcot-Marie-Tooth disease type 2D (CMT2D), caused by dominant mutations in glycyl-tRNA synthetase (GARS). A de novo mutation in GARS was identified in a patient with a severe peripheral neuropathy, and a mouse model precisely recreating the mutation …

Characterization Of Resistance To A Potent D-Peptide Hiv Entry Inhibitor., Amanda R Smith, Matthew T Weinstock, Amanda E Siglin, Frank G Whitby, J Nicholas Francis, Christopher P Hill, Debra M Eckert, Michael J Root, Michael S Kay

Department of Biochemistry and Molecular Biology Faculty Papers

BACKGROUND: PIE12-trimer is a highly potent D-peptide HIV-1 entry inhibitor that broadly targets group M isolates. It specifically binds the three identical conserved hydrophobic pockets at the base of the gp41 N-trimer with sub-femtomolar affinity. This extremely high affinity for the transiently exposed gp41 trimer provides a reserve of binding energy (resistance capacitor) to prevent the viral resistance pathway of stepwise accumulation of modest affinity-disrupting mutations. Such modest mutations would not affect PIE12-trimer potency and therefore not confer a selective advantage. Viral passaging in the presence of escalating PIE12-trimer concentrations ultimately selected for PIE12-trimer resistant populations, but required an extremely …

Structural And Functional Analysis Of Parameters Governing Tankyrase-1 Interaction With Telomeric Repeat-Binding Factor 1 And Gdp-Mannose 4,6-Dehydratase., Travis Eisemann, Marie-France Langelier, John M. Pascal

Department of Biochemistry and Molecular Biology Faculty Papers

Human tankyrase-1 (TNKS) is a member of the poly(ADPribose) polymerase (PARP) superfamily of proteins that posttranslationally modify themselves and target proteins with ADP-ribose (termed PARylation). The TNKS ankyrin repeat domain mediates interactions with a growing number of structurally and functionally diverse binding partners, linking TNKS activity to multiple critical cell processes, including Wnt signaling, Golgi trafficking, and telomere maintenance. However, some binding partners can engage TNKS without being modified, suggesting that separate parameters influence TNKS interaction and PARylation. Here, we present an analysis of the sequence and structural features governing TNKS interactions with two model binding partners: The PARylated partner …

Ip3 Receptor Isoforms Differently Regulate Er-Mitochondrial Contacts And Local Calcium Transfer, Adam Bartok, David Weaver, Tünde Golenár, Zuzana Nichtova, Máté Katona, Száva Bánsághi, Kamil J. Alzayady, V. Kaye Thomas, Hideaki Ando, Katsuhiko Mikoshiba, Suresh K. Joseph, David I. Yule, György Csordás, György Hajnóczky

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

Contact sites of endoplasmic reticulum (ER) and mitochondria locally convey calcium signals between the IP₃ receptors (IP3R) and the mitochondrial calcium uniporter, and are central to cell survival. It remains unclear whether IP3Rs also have a structural role in contact formation and whether the different IP3R isoforms have redundant functions. Using an IP3R-deficient cell model rescued with each of the three IP3R isoforms and an array of super-resolution and ultrastructural approaches we demonstrate that IP3Rs are required for maintaining ER-mitochondrial contacts. This role is independent of calcium fluxes. We also show that, while each isoform can support contacts, type …

Myc-Mediated Transcriptional Regulation Of The Mitochondrial Chaperone Trap1 Controls Primary And Metastatic Tumor Growth., Ekta Agarwal, Brian J. Altman, Jae Ho Seo, Jagadish C. Ghosh, Andrew V Kossenkov, Hsin-Yao Tang, Shiv Ram Krishn, Lucia R. Languino, Dmitry I. Gabrilovich, David W. Speicher, Chi V. Dang, Dario C. Altieri

Department of Cancer Biology Faculty Papers

The role of mitochondria in cancer continues to be debated, and whether exploitation of mitochondrial functions is a general hallmark of malignancy or a tumor- or context-specific response is still unknown. Using a variety of cancer cell lines and several technical approaches, including siRNA-mediated gene silencing, ChIP assays, global metabolomics and focused metabolite analyses, bioenergetics, and cell viability assays, we show that two oncogenic Myc proteins, c-Myc and N-Myc, transcriptionally control the expression of the mitochondrial chaperone TNFR-associated protein- 1 (TRAP1) in cancer. In turn, this Myc-mediated regulation preserved the folding and function of mitochondrial oxidative phosphorylation (OXPHOS) complex II …

A Proline Insertion-Deletion In The Spike Glycoprotein Fusion Peptide Of Mouse Hepatitis Virus Strongly Alters Neuropathology., Manmeet Singh, Abhinoy Kishore, Dibyajyoti Maity, Punnepalli Sunanda, Bankala Krishnarjuna, Sreeparna Vappala, Srinivasarao Raghothama, Lawrence C. Kenyon, Debnath Pal, Jayasri Das Sarma

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

Fusion peptides (FPs) in spike proteins are key players mediating early events in cell-to-cell fusion, vital for intercellular viral spread. A proline residue located at the central FP region has often been suggested to have a distinctive role in this fusion event. The spike glycoprotein from strain RSA59 (PP) of mouse hepatitis virus (MHV) contains two central, consecutive prolines in the FP. Here, we report that deletion of one of these proline residues, resulting in RSA59 (P), significantly affected neural cell syncytia formation and viral titers postinfection in vitro. Transcranial inoculation of C57Bl/6 mice with RSA59 (PP) or RSA59 (P) …

A Unique Role For Clathrin Light Chain A In Cell Spreading And Migration., Oxana M. Tsygankova, James H. Keen

Department of Biochemistry and Molecular Biology Faculty Papers

Clathrin heavy chain is the structural component of the clathrin triskelion, but unique functions for the two distinct and highly conserved clathrin light chains (CLCa and CLCb, also known as CLTA and CLTB, respectively) have been elusive. Here, we show that following detachment and replating, CLCa is uniquely responsible for promoting efficient cell spreading and migration. Selective depletion of CLCa, but not of CLCb, reduced the initial phase of isotropic spreading of HeLa, H1299 and HEK293 cells by 60-80% compared to siRNA controls, and wound closure and motility by ∼50%. Surface levels of β1-integrins were unaffected by CLCa depletion. However, …

Hit And Run Versus Long-Term Activation Of Parp-1 By Its Different Domains Fine-Tunes Nuclear Processes., Colin Thomas, Md, Yingbiao Ji, Chao Wu, Haily Datz, Cody Boyle, Brett Macleod, Shri Patel, Michelle Ampofo, Michelle Currie, Jonathan Harbin, Kate Pechenkina, Niraj Lodhi, Sarah J. Johnson, Alexei V. Tulin

Department of Medicine Faculty Papers

Poly(ADP-ribose) polymerase 1 (PARP-1) is a multidomain multifunctional nuclear enzyme involved in the regulation of the chromatin structure and transcription. PARP-1 consists of three functional domains: the N-terminal DNA-binding domain (DBD) containing three zinc fingers, the automodification domain (A), and the C-terminal domain, which includes the protein interacting WGR domain (W) and the catalytic (Cat) subdomain responsible for the poly(ADP ribosyl)ating reaction. The mechanisms coordinating the functions of these domains and determining the positioning of PARP-1 in chromatin remain unknown. Using multiple deletional isoforms of PARP-1, lacking one or another of its three domains, as well as consisting of only …

Trna Methylation Is A Global Determinant Of Bacterial Multi-Drug Resistance., Isao Masuda, Ryuma Matsubara, Thomas Christian, Enrique R. Rojas, Srujana S. Yadavalli, Lisheng Zhang, Mark Goulian, Leonard J. Foster, Kerwyn Casey Huang, Ya-Ming Hou

Department of Biochemistry and Molecular Biology Faculty Papers

Gram-negative bacteria are intrinsically resistant to drugs because of their double-membrane envelope structure that acts as a permeability barrier and as an anchor for efflux pumps. Antibiotics are blocked and expelled from cells and cannot reach high-enough intracellular concentrations to exert a therapeutic effect. Efforts to target one membrane protein at a time have been ineffective. Here, we show that m ¹ G37-tRNA methylation determines the synthesis of a multitude of membrane proteins via its control of translation at proline codons near the start of open reading frames. Decreases in m ¹ G37 levels in Escherichia coli and Salmonella impair …

Gasdermin Pores Permeabilize Mitochondria To Augment Caspase-3 Activation During Apoptosis And Inflammasome Activation., Corey Rogers, Dan A. Erkes, Alexandria Nardone, Andrew E. Aplin, Teresa Fernandes-Alnemri, Emad S. Alnemri

Department of Biochemistry and Molecular Biology Faculty Papers

Gasdermin E (GSDME/DFNA5) cleavage by caspase-3 liberates the GSDME-N domain, which mediates pyroptosis by forming pores in the plasma membrane. Here we show that GSDME-N also permeabilizes the mitochondrial membrane, releasing cytochrome c and activating the apoptosome. Cytochrome c release and caspase-3 activation in response to intrinsic and extrinsic apoptotic stimuli are significantly reduced in GSDME-deficient cells comparing with wild type cells. GSDME deficiency also accelerates cell growth in culture and in a mouse model of melanoma. Phosphomimetic mutation of the highly conserved phosphorylatable Thr6 residue of GSDME, inhibits its pore-forming activity, thus uncovering a potential mechanism by which GSDME …

Role Of Ribosome Recycling Factor As A Ribosome Releasing Factor, Yoshio Inokuchi, Fabio Quaglia, Akikazu Hirashima, Yoshihiro Yamamoto, Hideko Kaji, A. Kaji

Department of Biochemistry and Molecular Biology Posters

The objective of this presentation is to study the in vivo actions of ribosome recycling factor (RRF) and compare them with those found in vitro. RRF is known to catalyze three separate reactions: release of tRNA and mRNA from the post-termination complex (PoTC), and splitting of the ribosome of the PoTC. To study the mechanism of RRF reaction in vivo, we used E. coli harboring temperature sensitive (ts) RRF and assayed by following downstream reading of translationally coupled ORF. At the non-permissive temperature, ribosomes remain on the termination codon of the junction sequence of coupled ORFs and translate downstream ORF …

Loss-Of-Function Mutations In Lysyl-Trna Synthetase Cause Various Leukoencephalopathy Phenotypes, Chong Sun, Jie Song, Yanjun Jiang, Chongbo Zhao, Jiahong Lu, Yuxin Li, Yin Wang, Mingshi Gao, Jianying Xi, Sushan Luo, Meixia Li, Kevin Donaldson, Stephanie N. Oprescu, Thomas P. Slavin, Sansan Lee, Pilar L. Magoulas, Andrea M. Lewis, Lisa Emrick, Seema R. Lalani, Zhiyv Niu, Megan L. Landsverk, Magdalena Walkiewicz, Richard E. Person, Hui Mei, Jill A. Rosenfeld, Yaping Yang, Anthony Antonellis, Ya-Ming Hou, Jie Lin, Victor W. Zhang

Department of Biochemistry and Molecular Biology Faculty Papers

Objective: To expand the clinical spectrum of lysyl-tRNA synthetase (KARS) gene–related diseases, which so far includes Charcot-Marie-Tooth disease, congenital visual impairment and microcephaly, and nonsyndromic hearing impairment.

Methods: Whole-exome sequencing was performed on index patients from 4 unrelated families with leukoencephalopathy. Candidate pathogenic variants and their cosegregation were confirmed by Sanger sequencing. Effects of mutations on KARS protein function were examined by aminoacylation assays and yeast complementation assays.

Results: Common clinical features of the patients in this study included impaired cognitive ability, seizure, hypotonia, ataxia, and abnormal brain imaging, suggesting that the CNS involvement is the main …

Interaction Between The Bag1s Isoform And Hsp70 Mediates The Stability Of Anti-Apoptotic Proteins And The Survival Of Osteosarcoma Cells Expressing Oncogenic Myc., Victoria J. Gennaro, Helen Wedegaertner, Steven B. Mcmahon

Department of Biochemistry and Molecular Biology Faculty Papers

BACKGROUND: The oncoprotein MYC has the dual capacity to drive cell cycle progression or induce apoptosis, depending on the cellular context. BAG1 was previously identified as a transcriptional target of MYC that functions as a critical determinant of this cell fate decision. The BAG1 protein is expressed as multiple isoforms, each having an array of distinct biochemical functions; however, the specific effector function of BAG1 that directs MYC-dependent cell survival has not been defined.

METHODS: In our studies the human osteosarcoma line U2OS expressing a conditional MYC-ER allele was used to induce oncogenic levels of MYC. We interrogated MYC-driven survival …

Investigating Gαs Pepducin’S Effect On Β2ar Signaling For Chf Pharmacology, Nida Bajwa, Nathan Hopfinger, Charles Scott

Phase 1

Introduction: Congestive heart failure affects nearly six million Americans and significantly impairs their quality of life. New and better interventions are needed to improve HF patients’ survival and outcomes. Pharmacologics that bias β2AR signaling towards arrestin, which promotes cardiomyocyte survival and contractility, may offer advantages over traditional β-blockers.

Objective: It has been demonstrated that peptides mimicking the C-terminus of the Gα_s subunit block downstream signaling of GPCRs. The study’s objective is to determine if a pepducin derived from the C-terminus of the Gα_s subunit of the β2AR could block G_s signaling but maintain arrestin-recruitment, thereby producing a …

Impaired Nuclear Export Of Polyglutamine-Expanded Androgen Receptor In Spinal And Bulbar Muscular Atrophy., Frederick J. Arnold, Anna Pluciennik, Diane E. Merry

Department of Biochemistry and Molecular Biology Faculty Papers

Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease caused by polyglutamine (polyQ) expansion in the androgen receptor (AR). Prior studies have highlighted the importance of AR nuclear localization in SBMA pathogenesis; therefore, in this study, we sought to determine the role of AR nuclear export in the pathological manifestations of SBMA. We demonstrate here that the nuclear export of polyQ-expanded AR is impaired, even prior to the formation of intranuclear inclusions of aggregated AR. Additionally, we find that promoting AR export with an exogenous nuclear export signal substantially reduces its aggregation and blocks hormone-induced toxicity. Moreover, we show …

Codon-Specific Translation By M1g37 Methylation Of Trna, Ya-Ming Hou, Isao Masuda, Howard Gamper

Department of Biochemistry and Molecular Biology Faculty Papers

Although the genetic code is degenerate, synonymous codons for the same amino acid are not translated equally. Codon-specific translation is important for controlling gene expression and determining the proteome of a cell. At the molecular level, codon-specific translation is regulated by post-transcriptional epigenetic modifications of tRNA primarily at the wobble position 34 and at position 37 on the 3′-side of the anticodon. Modifications at these positions determine the quality of codon-anticodon pairing and the speed of translation on the ribosome. Different modifications operate in distinct mechanisms of codon-specific translation, generating a diversity of regulation that is previously unanticipated. Here we …