Medical Biochemistry Commons^™

Characterizing The Effects Of Antimuscarinics On Rhoa Signaling, Zuhra Tukhtamisheva, Elizabeth L. Mcduffie, Jordan Lee, Steven S. An, Reynold A. Panettieri Jr., Charles Scott

Alpha Omega Alpha Research Symposium Posters

Purpose: Airway hyperresponsiveness in asthma is driven by acetylcholine-mediated activation of the muscarinic acetylcholine 3 receptor (M3R), promoting bronchoconstriction, mucus hypersecretion, and airway remodeling. Despite directly targeting this pathway, antimuscarinics remain adjunctive rather than first-line therapy, suggesting a disconnect between biological rationale and clinical efficacy. Recent work from the Scott Lab at Thomas Jefferson University demonstrates that M3R in human airway smooth muscle (HASM) cells drives muscle shortening through G_12/13–driven RhoA signaling rather than through G_q/11-dependent calcium flux. We therefore investigated whether clinically prescribed antimuscarinics effectively inhibit G_12/13-dependent RhoA signaling in HASM cells.

Methods: …

Structural And Molecular Basis Of Pcna-Activated Fan1 Nuclease Function In Dna Repair, F. Li, A. S. Phadte, M. Bhatia, S. Barndt, A.R. Monte Carlo, Iii, C.F.D. Hou, R. Yang, S. Strock, A. Pluciennik

Department of Biochemistry and Molecular Biology Faculty Papers

FAN1 is a DNA dependent nuclease whose proper function is essential for maintaining human health. For example, a genetic variant in FAN1, Arg507 to His hastens onset of Huntington's disease, a repeat expansion disorder for which there is no cure. How the Arg507His mutation affects FAN1 structure and enzymatic function is unknown. Using cryo-EM and biochemistry, we have discovered that FAN1 arginine 507 is critical for its interaction with PCNA, and mutation of Arg507 to His attenuates assembly of the FAN1-PCNA complex on a disease-relevant extrahelical DNA extrusions formed within DNA repeats. This mutation concomitantly abolishes PCNA-FAN1-dependent cleavage of such …

Short-Course Subcutaneous Alemtuzumab Induces Clinical Responses In Relapsed T-Cell Large Granular Leukemia, Miguel Ruiz, Zachary Braunstein, Eric Mclaughlin, Anjali Mishra, Pierluigi Porcu, Jonathan E. Brammer

Department of Medical Oncology Faculty Papers

No abstract provided.

The Mapk Homolog, Smk1, Promotes Assembly Of The Glucan Layer Of The Spore Wall In S. Cerevisiae, Julia Y. Lee-Soety, Gwendolyn Resch, Abhimannyu Rimal, Erica S. Johnson, Jonathan Benway, Edward Winter

Department of Biochemistry and Molecular Biology Faculty Papers

Smk1 is a MAPK homolog in the yeast Saccharomyces cerevisiae that controls the postmeiotic program of spore wall assembly. During this program, haploid cells are surrounded by a layer of mannan and then a layer of glucan. These inner layers of the spore wall resemble the vegetative cell wall. Next, the outer layers consisting of chitin/chitosan and then dityrosine are assembled. The outer layers are spore-specific and provide protection against environmental stressors. Smk1 is required for the proper assembly of spore walls. However, the protective properties of the outer layers have limited our understanding of how Smk1 controls this morphogenetic …

Structural Basis For Nuclear Import Of Hepatitis B Virus (Hbv) Nucleocapsid Core, Ruoyu Yang, Ying-Hui Ko, Fenglin Li, Ravi K. Lokareddy, Chun-Feng David Hou, Christine Kim, Shelby Klein, Santiago Antolínez, Juan F. Marín, Carolina Pérez-Segura, Martin F. Jarrold, Adam Zlotnick, Jodi A. Hadden-Perilla, Gino Cingolani

Student Papers, Posters & Projects

Nuclear import of the hepatitis B virus (HBV) nucleocapsid is essential for replication that occurs in the nucleus. The ~360-angstrom HBV capsid translocates to the nuclear pore complex (NPC) as an intact particle, hijacking human importins in a reaction stimulated by host kinases. This paper describes the mechanisms of HBV capsid recognition by importins. We found that importin α1 binds a nuclear localization signal (NLS) at the far end of the HBV coat protein Cp183 carboxyl-terminal domain (CTD). This NLS is exposed to the capsid surface through a pore at the icosahedral quasi-sixfold vertex. Phosphorylation at serine-155, serine-162, and serine-170 …

On A Sugar High: Role Of O-Glcnacylation In Cancer, Giang Le Minh, Emily M. Esquea, Riley G. Young, Jessie Huang, Mauricio J. Reginato

Kimmel Cancer Center Papers, Presentations, and Grand Rounds

Recent advances in the understanding of the molecular mechanisms underlying cancer progression have led to the development of novel therapeutic targeting strategies. Aberrant glycosylation patterns and their implication in cancer have gained increasing attention as potential targets due to the critical role of glycosylation in regulating tumor-specific pathways that contribute to cancer cell survival, proliferation, and progression. A special type of glycosylation that has been gaining momentum in cancer research is the modification of nuclear, cytoplasmic, and mitochondrial proteins, termed O-GlcNAcylation. This protein modification is catalyzed by an enzyme called O-GlcNAc transferase (OGT), which uses the final product of the …

Development Of A Sensitive Microplate Assay For Characterizing Rna Methyltransferase Activity: Implications For Epitranscriptomics And Drug Development, Isaiah K. Mensah, Allison B. Norvil, Ming He, Emma Lendy, Nicole Hjortland, Hern Tan, Richard T. Pomerantz, Andrew Mesecar, Humaira Gowher

Department of Biochemistry and Molecular Biology Faculty Papers

RNA methylation is a ubiquitous post-transcriptional modification found in diverse RNA classes and is a critical regulator of gene expression. In this study, we used Zika virus RNA methyltransferase (MTase) to develop a highly sensitive microplate assay that uses a biotinylated RNA substrate and radiolabeled AdoMet coenzyme. The assay is fast, highly reproducible, exhibits linear progress-curve kinetics under multiple turnover conditions, has high sensitivity in competitive inhibition assays, and significantly lower background levels compared with the currently used method. Using our newly developed microplate assay, we observed no significant difference in the catalytic constants of the full-length nonstructural protein 5 …

Fan1 Removes Triplet Repeat Extrusions Via A Pcna- And Rfc-Dependent Mechanism, Ashutosh S. Phadte, Mayuri Bhatia, Hope Ebert, Haaris Abdullah, Essam Abed Elrazaq, Konstantin E. Komolov, Anna Pluciennik

Department of Biochemistry and Molecular Biology Faculty Papers

Human genome-wide association studies have identified FAN1 and several DNA mismatch repair (MMR) genes as modifiers of Huntington’s disease age of onset. In animal models, FAN1 prevents somatic expansion of CAG triplet repeats, whereas MMR proteins promote this process. To understand the molecular basis of these opposing effects, we evaluated FAN1 nuclease function on DNA extrahelical extrusions that represent key intermediates in triplet repeat expansion. Here, we describe a strand-directed, extrusion-provoked nuclease function of FAN1 that is activated by RFC, PCNA, and ATP at physiological ionic strength. Activation of FAN1 in this manner results in DNA cleavage in the vicinity …

Changes In Nascent Chromatin Structure Regulate Activation Of The Pro-Fibrotic Transcriptome And Myofibroblast Emergence In Organ Fibrosis, Morgan D. Basta, Svetlana Petruk, Ross Summer, Joel Rosenbloom, Peter J. Wermuth, Edward J. Macarak, Alex V. Levin, Alexander Mazo, Janice L. Walker

Department of Biochemistry and Molecular Biology Faculty Papers

Cell reprogramming to a myofibroblast responsible for the pathological accumulation of extracellular matrix is fundamental to the onset of fibrosis. Here, we explored how condensed chromatin structure marked by H3K72me3 becomes modified to allow for activation of repressed genes to drive emergence of myofibroblasts. In the early stages of myofibroblast precursor cell differentiation, we discovered that H3K27me3 demethylase enzymes UTX/KDM6B creates a delay in the accumulation of H3K27me3 on nascent DNA revealing a period of decondensed chromatin structure. This period of decondensed nascent chromatin structure allows for binding of pro-fibrotic transcription factor, Myocardin-related transcription factor A (MRTF-A) to nascent DNA. …

A Computationally Designed Ace2 Decoy Has Broad Efficacy Against Sars-Cov-2 Omicron Variants And Related Viruses In Vitro And In Vivo, Brandon Havranek, Graeme Walker Lindsey, Yusuke Higuchi, Yumi Itoh, Tatsuya Suzuki, Toru Okamoto, Atsushi Hoshino, Erik Procko, Shahidul M. Islam

SKMC Student Presentations and Publications

SARS-CoV-2, especially B.1.1.529/omicron and its sublineages, continues to mutate to evade monoclonal antibodies and antibodies elicited by vaccination. Affinity-enhanced soluble ACE2 (sACE2) is an alternative strategy that works by binding the SARS-CoV-2 S protein, acting as a 'decoy' to block the interaction between the S and human ACE2. Using a computational design strategy, we designed an affinity-enhanced ACE2 decoy, FLIF, that exhibited tight binding to SARS-CoV-2 delta and omicron variants. Our computationally calculated absolute binding free energies (ABFE) between sACE2:SARS-CoV-2 S proteins and their variants showed excellent agreement to binding experiments. FLIF displayed robust therapeutic utility against a broad range …

Candidate Variants In Dna Replication And Repair Genes In Early-Onset Renal Cell Carcinoma Patients Referred For Germline Testing, Elena V. Demidova, Ilya G. Serebriiskii, Ramilia Vlasenkova, Simon Kelow, Mark D. Andrake, Tiffiney R. Hartman, Tatiana Kent, James Virtucio, Gail L. Rosen, Richard T. Pomerantz, Roland L. Dunbrack, Erica A. Golemis, Michael J. Hall, David Y.T. Chen, Mary B. Daly, Sanjeevani Arora

Department of Biochemistry and Molecular Biology Faculty Papers

Background: Early-onset renal cell carcinoma (eoRCC) is typically associated with pathogenic germline variants (PGVs) in RCC familial syndrome genes. However, most eoRCC patients lack PGVs in familial RCC genes and their genetic risk remains undefined.

Methods: Here, we analyzed biospecimens from 22 eoRCC patients that were seen at our institution for genetic counseling and tested negative for PGVs in RCC familial syndrome genes.

Results: Analysis of whole-exome sequencing (WES) data found enrichment of candidate pathogenic germline variants in DNA repair and replication genes, including multiple DNA polymerases. Induction of DNA damage in peripheral blood monocytes (PBMCs) significantly elevated numbers of …

Facile Green Synthesis Of Cinnamomum Tamala Extract Capped Silver Nanoparticles And Its Biological Applications, Sajina Narath, S. Sharath Shankar, Saranya Kothaplamoottil Sivan, Bini George, T. Dennis Thomas, Sankarannair Sabarinath, Sajithkumar K. Jayaprakash, Stanisław Wacławek, Vinod V.T. Padil

Department of Medicine Faculty Papers

The plant mediated biogenic synthesis of nanoparticles is of magnificent concern due to its eco-benign and single pot nature. Here, Cinnamomum tamala (C. tamala) aqueous leaf extract was utilised for the silver nanoparticles’ (Ag NPs) synthesis. The phytoconstituents in the leaf extract were analysed by standard methods. These metabolites, especially carbohydrate polymers reduce Ag ions to Ag NPs accompanied by a reddish-brown coloration of the reaction mixture. The visual observation of intense brown colour is the first indication of the formation of Ag NPs. Various spectro-analytical techniques further characterise the Ag NPs. The green synthesised spherical Ag NPs were crystalline …

Harnessing Transcriptionally Driven Chromosomal Instability Adaptation To Target Therapy-Refractory Lethal Prostate Cancer., Brittiny Dhital, Sandra Santasusagna, Perumalraja Kirthika, Michael Xu, Peiyao Li, Marc Carceles-Cordon, Rajesh K. Soni, Zhuoning Li, Ronald C. Hendrickson, Matthew J. Schiewer, William K. Kelly, Cora N. Sternberg, Jun Luo, Amaia Lujambio, Carlos Cordon-Cardo, Monica Alvarez-Fernandez, Marcos Malumbres, Haojie Huang, Adam Ertel, Josep Domingo-Domenech, Veronica Rodriguez-Bravo

Kimmel Cancer Center Papers, Presentations, and Grand Rounds

Metastatic prostate cancer (PCa) inevitably acquires resistance to standard therapy preceding lethality. Here, we unveil a chromosomal instability (CIN) tolerance mechanism as a therapeutic vulnerability of therapy-refractory lethal PCa. Through genomic and transcriptomic analysis of patient datasets, we find that castration and chemotherapy-resistant tumors display the highest CIN and mitotic kinase levels. Functional genomics screening coupled with quantitative phosphoproteomics identify MASTL kinase as a survival vulnerability specific of chemotherapy-resistant PCa cells. Mechanistically, MASTL upregulation is driven by transcriptional rewiring mechanisms involving the non-canonical transcription factors androgen receptor splice variant 7 and E2F7 in a circuitry that restrains deleterious CIN and …

Semi-Quantitative Detection Of Pseudouridine Modifications And Type I/Ii I/Ii Hypermodifications In Human Mrnas Using Direct Long-Read Sequencing, Sepideh Tavakoli, Mohammad Nabizadeh, Amr Makhamreh, Howard Gamper, Caroline A Mccormick, Neda K Rezapour, Ya-Ming Hou, Meni Wanunu, Sara H Rouhanifard

Department of Biochemistry and Molecular Biology Faculty Papers

Here, we develop and apply a semi-quantitative method for the high-confidence identification of pseudouridylated sites on mammalian mRNAs via direct long-read nanopore sequencing. A comparative analysis of a modification-free transcriptome reveals that the depth of coverage and specific k-mer sequences are critical parameters for accurate basecalling. By adjusting these parameters for high-confidence U-to-C basecalling errors, we identify many known sites of pseudouridylation and uncover previously unreported uridine-modified sites, many of which fall in k-mers that are known targets of pseudouridine synthases. Identified sites are validated using 1000-mer synthetic RNA controls bearing a single pseudouridine in the center position, demonstrating systematic …

Disruption Of The Interaction Between Mutationally Activated Gαq And Gβγ Attenuates Aberrant Signaling, Jenna L Aumiller, Philip B Wedegaertner

Department of Biochemistry and Molecular Biology Faculty Papers

Heterotrimeric G protein stimulation via G protein-coupled receptors promotes downstream proliferative signaling. Mutations can occur in Gα proteins which prevent GTP hydrolysis; this allows the G proteins to signal independently of G protein-coupled receptors and can result in various cancers, such as uveal melanoma (UM). Most UM cases harbor Q209L, Q209P, or R183C mutations in Gαq/11 proteins, rendering the proteins constitutively active (CA). Although it is generally thought that active, GTP-bound Gα subunits are dissociated from and signal independently of Gβγ, accumulating evidence indicates that some CA Gα mutants, such as Gαq/11, retain binding to Gβγ, and this interaction is …

Differentiating Pc12 Cells To Evaluate Neurite Densities Through Live-Cell Imaging, Jordyn Karliner, Diane E Merry

Department of Biochemistry and Molecular Biology Faculty Papers

Although PC12 cells are a valuable tool in neuroscience research, previously published PC12 cell differentiation techniques fail to consider the variability in differentiation rates between different PC12 cell strains and clonal variants. Here, we present a comprehensive protocol to differentiate PC12 cells into equivalent neurite densities through live-cell imaging for morphological, immunocytochemical, and biochemical analyses. We detail steps on optimized substrate coating, plating techniques, culture media, validation steps, and quantification techniques.

In Silico Identification Of A Β2-Adrenoceptor Allosteric Site That Selectively Augments Canonical Β2ar-Gs Signaling And Function, Sushrut D Shah, Christoffer Lind, Francesco De Pascali, Raymond B Penn, Alexander D Mackerell, Deepak A Deshpande

Department of Biochemistry and Molecular Biology Faculty Papers

Activation of β2-adrenoceptors (β2ARs) causes airway smooth muscle (ASM) relaxation and bronchodilation, and β2AR agonists (β-agonists) are front-line treatments for asthma and other obstructive lung diseases. However, the therapeutic efficacy of β-agonists is limited by agonist-induced β2AR desensitization and noncanonical β2AR signaling involving β-arrestin that is shown to promote asthma pathophysiology. Accordingly, we undertook the identification of an allosteric site on β2AR that could modulate the activity of β-agonists to overcome these limitations. We employed the site identification by ligand competitive saturation (SILCS) computational method to comprehensively map the entire 3D structure of in silico-generated β2AR intermediate conformations and identified …

Terminase Subunits From The Pseudomonas-Phage E217, Ravi K Lokareddy, Chun-Feng David Hou, Steven G Doll, Fenglin Li, Richard E Gillilan, Francesca Forti, David S Horner, Federica Briani, Gino Cingolani

Department of Biochemistry and Molecular Biology Faculty Papers

Pseudomonas phages are increasingly important biomedicines for phage therapy, but little is known about how these viruses package DNA. This paper explores the terminase subunits from the Myoviridae E217, a Pseudomonas-phage used in an experimental cocktail to eradicate P. aeruginosa in vitro and in animal models. We identified the large (TerL) and small (TerS) terminase subunits in two genes ∼58 kbs away from each other in the E217 genome. TerL presents a classical two-domain architecture, consisting of an N-terminal ATPase and C-terminal nuclease domain arranged into a bean-shaped tertiary structure. A 2.05 Å crystal structure of the C-terminal domain revealed …

Structure Of The Pre-Mrna Leakage 39-Kda Protein Reveals A Single Domain Of Integrated Zf-C3hc And Rsm1 Modules, Hideharu Hashimoto, Daniel H. Ramirez, Ophélie Lautier, Natalie Pawlak, Günter Blobel, Benoît Palancade, Erik W. Debler

Department of Biochemistry and Molecular Biology Faculty Papers

In Saccharomyces cerevisiae, the pre-mRNA leakage 39-kDa protein (ScPml39) was reported to retain unspliced pre-mRNA prior to export through nuclear pore complexes (NPCs). Pml39 homologs outside the Saccharomycetaceae family are currently unknown, and mechanistic insight into Pml39 function is lacking. Here we determined the crystal structure of ScPml39 at 2.5 Å resolution to facilitate the discovery of orthologs beyond Saccharomycetaceae, e.g. in Schizosaccharomyces pombe or human. The crystal structure revealed integrated zf-C3HC and Rsm1 modules, which are tightly associated through a hydrophobic interface to form a single domain. Both zf-C3HC and Rsm1 modules belong to the Zn-containing BIR (Baculovirus IAP …

Viral Small Terminase: A Divergent Structural Framework For A Conserved Biological Function., Ravi K. Lokareddy, Chun-Feng David Hou, Fenglin Li, Ruoyu Yang, Gino Cingolani

Department of Biochemistry and Molecular Biology Faculty Papers

The genome packaging motor of bacteriophages and herpesviruses is built by two terminase subunits, known as large (TerL) and small (TerS), both essential for viral genome packaging. TerL structure, composition, and assembly to an empty capsid, as well as the mechanisms of ATP-dependent DNA packaging, have been studied in depth, shedding light on the chemo-mechanical coupling between ATP hydrolysis and DNA translocation. Instead, significantly less is known about the small terminase subunit, TerS, which is dispensable or even inhibitory in vitro, but essential in vivo. By taking advantage of the recent revolution in cryo-electron microscopy (cryo-EM) and building upon a …

The Role Of Ubiquitination In Spinal And Bulbar Muscular Atrophy, Medha Sengupta, Anna Pluciennik, Diane E. Merry

Department of Biochemistry and Molecular Biology Faculty Papers

Spinal and bulbar muscular atrophy (SBMA) is a neurodegenerative and neuromuscular genetic disease caused by the expansion of a polyglutamine-encoding CAG tract in the androgen receptor (AR) gene. The AR is an important transcriptional regulator of the nuclear hormone receptor superfamily; its levels are regulated in many ways including by ubiquitin-dependent degradation. Ubiquitination is a post-translational modification (PTM) which plays a key role in both AR transcriptional activity and its degradation. Moreover, the ubiquitin-proteasome system (UPS) is a fundamental component of cellular functioning and has been implicated in diseases of protein misfolding and aggregation, including polyglutamine (polyQ) repeat expansion diseases …

Young Transposable Elements Rewired Gene Regulatory Networks In Human And Chimpanzee Hippocampal Intermediate Progenitors, Sruti Patoori, Samantha M Barnada, Christopher Large, John I Murray, Marco Trizzino

Department of Biochemistry and Molecular Biology Faculty Papers

The hippocampus is associated with essential brain functions, such as learning and memory. Human hippocampal volume is significantly greater than expected compared with that of non-human apes, suggesting a recent expansion. Intermediate progenitors, which are able to undergo multiple rounds of proliferative division before a final neurogenic division, may have played a role in evolutionary hippocampal expansion. To investigate the evolution of gene regulatory networks underpinning hippocampal neurogenesis in apes, we leveraged the differentiation of human and chimpanzee induced pluripotent stem cells into TBR2 (or EOMES)-positive hippocampal intermediate progenitor cells (hpIPCs). We found that the gene networks active in hpIPCs …

Enhanced Membrane Binding Of Oncogenic G Protein Αqq209l Confers Resistance To Inhibitor Ym-254890, Clinita E. Randolph, Morgan B. Dwyer, Jenna L. Aumiller, Alethia J. Dixon, Asuka Inoue, Patrick Osei-Owusu, Philip B. Wedegaertner

Department of Biochemistry and Molecular Biology Faculty Papers

Heterotrimeric G proteins couple activated G protein-coupled receptors (GPCRs) to intracellular signaling pathways. They can also function independently of GPCR activation upon acquiring mutations that prevent GTPase activity and result in constitutive signaling, as occurs with the αqQ209L mutation in uveal melanoma. YM-254890 (YM) can inhibit signaling by both GPCR-activated WT αq and GPCR-independent αqQ209L. Although YM inhibits WT αq by binding to αq-GDP and preventing GDP/GTP exchange, the mechanism of YM inhibition of cellular αqQ209L remains to be fully understood. Here, we show that YM promotes a subcellular redistribution of αqQ209L from the plasma membrane (PM) to the cytoplasm. …

Isc10, An Inhibitor Of The Smk1 Mapk, Prevents Activation Loop Autophosphorylation And Substrate Phosphorylation Through Separate Mechanisms, Abhimannyu Rimal, Thomas M Swayne, Zeal P Kamdar, Madison A Tewey, Edward Winter

Department of Biochemistry and Molecular Biology Faculty Papers

Many eukaryotic protein kinases are activated by the intramolecular autophosphorylation of activation loop residues. Smk1 is a meiosis-specific mitogen-activated protein kinase (MAPK) in yeast that autophosphorylates its activation loop tyrosine and thereby upregulates catalytic output. This reaction is controlled by an inhibitor, Isc10, that binds the MAPK during meiosis I and an activator, Ssp2, that binds Smk1/Isc10 during meiosis II. Upon completion of the meiotic divisions, Isc10 is degraded, and Smk1 undergoes autophosphorylation to generate the high activity form of the MAPK that controls spore formation. How Isc10 inhibits Smk1 is not clear. Here, we use a bacterial coexpression/reconstitution system …

The Pro-Fibrotic Response To Lens Injury Is Signaled In A Pi3k Isoform-Specific Manner, A. Sue Menko, Janice L. Walker

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

The signaling inputs that function to integrate biochemical and mechanical cues from the extracellular environment to alter the wound-repair outcome to a fibrotic response remain poorly understood. Here, using a clinically relevant post-cataract surgery wound healing/fibrosis model, we investigated the role of Phosphoinositide-3-kinase (PI3K) class I isoforms as potential signaling integrators to promote the proliferation, emergence and persistence of collagen I-producing alpha smooth muscle actin (αSMA+) myofibroblasts that cause organ fibrosis. Using PI3K isoform specific small molecule inhibitors, our studies revealed a requisite role for PI3K p110α in signaling the CD44+ mesenchymal leader cell population that we previously identified as …

G Protein-Coupled Receptor Kinase 6 (Grk6) Regulates Insulin Processing And Secretion Via Effects On Proinsulin Conversion To Insulin, Matthew J Varney, Wouter Steyaert, Paul J Coucke, Joris R Delanghe, David E Uehling, Babu Joseph, Richard Marcellus, Rima Al-Awar, Jeffrey L Benovic

Department of Biochemistry and Molecular Biology Faculty Papers

Recent studies identified a missense mutation in the gene coding for G protein-coupled receptor kinase 6 (GRK6) that segregates with type 2 diabetes (T2D). To better understand how GRK6 might be involved in T2D, we used pharmacological inhibition and genetic knockdown in the mouse β-cell line, MIN6, to determine whether GRK6 regulates insulin dynamics. We show inhibition of GRK5 and GRK6 increased insulin secretion but reduced insulin processing while GRK6 knockdown revealed these same processing defects with reduced levels of cellular insulin. GRK6 knockdown cells also had attenuated insulin secretion but enhanced proinsulin secretion consistent with decreased processing. In support …

Glucose Uptake By Glut1 In Photoreceptors Is Essential For Outer Segment Renewal And Rod Photoreceptor Survival, Lauren L. Daniele, John Y.S. Han, Ivy S Samuels, Ravikiran Komirisetty, Nikhil Mehta, Jessica L Mccord, Minzhong Yu, Yekai Wang, Kathleen Boesze-Battaglia, Brent A Bell, Jianhai Du, Neal S Peachey, Nancy J. Philp

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

Photoreceptors consume glucose supplied by the choriocapillaris to support phototransduction and outer segment (OS) renewal. Reduced glucose supply underlies photoreceptor cell death in inherited retinal degeneration and age-related retinal disease. We have previously shown that restricting glucose transport into the outer retina by conditional deletion of Slc2a1 encoding GLUT1 resulted in photoreceptor loss and impaired OS renewal. However, retinal neurons, glia, and the retinal pigment epithelium play specialized, synergistic roles in metabolite supply and exchange, and the cell-specific map of glucose uptake and utilization in the retina is incomplete. In these studies, we conditionally deleted Slc2a1 in a pan-retinal or …

Neuromuscular Junction Pathology Is Correlated With Differential Motor Unit Vulnerability In Spinal And Bulbar Muscular Atrophy, Elana Molotsky, Y Liu, Andrew P Lieberman, Diane E Merry

Department of Biochemistry and Molecular Biology Faculty Papers

Spinal and bulbar muscular atrophy (SBMA) is an X-linked, neuromuscular neurodegenerative disease for which there is no cure. The disease is characterized by a selective decrease in fast-muscle power (e.g., tongue pressure, grip strength) accompanied by a selective loss of fast-twitch muscle fibers. However, the relationship between neuromuscular junction (NMJ) pathology and fast-twitch motor unit vulnerability has yet to be explored. In this study, we used a cross-model comparison of two mouse models of SBMA to evaluate neuromuscular junction pathology, glycolytic-to-oxidative fiber-type switching, and cytoskeletal alterations in pre- and postsynaptic termini of tibialis anterior (TA), gastrocnemius, and soleus hindlimb muscles. …

Regulating Phase Transition In Neurodegenerative Diseases By Nuclear Import Receptors, Amandeep Girdhar, Lin Guo

Department of Biochemistry and Molecular Biology Faculty Papers

RNA-binding proteins (RBPs) with a low-complexity prion-like domain (PLD) can undergo aberrant phase transitions and have been implicated in neurodegenerative diseases such as ALS and FTD. Several nuclear RBPs mislocalize to cytoplasmic inclusions in disease conditions. Impairment in nucleocytoplasmic transport is another major event observed in ageing and in neurodegenerative disorders. Nuclear import receptors (NIRs) regulate the nucleocytoplasmic transport of different RBPs bearing a nuclear localization signal by restoring their nuclear localization. NIRs can also specifically dissolve or prevent the aggregation and liquid–liquid phase separation of wild-type or disease-linked mutant RBPs, due to their chaperoning activity. This review focuses on …

Recognition Of The Tdp-43 Nuclear Localization Signal By Importin Α1/Β, Steven G Doll, Hamed Meshkin, Alexander J Bryer, Fenglin Li, Ying-Hui Ko, Ravi K Lokareddy, Richard E Gillilan, Kushol Gupta, Juan R Perilla, Gino Cingolani

Department of Biochemistry and Molecular Biology Faculty Papers

Cytoplasmic mislocalization of the TAR-DNA binding protein of 43 kDa (TDP-43) leads to large, insoluble aggregates that are a hallmark of amyotrophic lateral sclerosis and frontotemporal dementia. Here, we study how importin α1/β recognizes TDP-43 bipartite nuclear localization signal (NLS). We find that the NLS makes extensive contacts with importin α1, especially at the minor NLS-binding site. NLS binding results in steric clashes with the C terminus of importin α1 that disrupts the TDP-43 N-terminal domain (NTD) dimerization interface. A putative phosphorylation site in the proximity of TDP-43 R83 at the minor NLS site destabilizes binding to importins by reducing …