Medical Cell Biology Commons^™

Long Acting Beta2-Adrenergic Receptor Agonists Reverse Diabetic Nephropathy And Liver Steatosis In Murine Models Of Diabetes And Are Associated With Protection In Retrospective Human Studies, Brennan Winkler

MUSC Theses and Dissertations

Diabetes Mellitus (DM) affects 13.9% of men and 14.3% of women worldwide, a total of approximately 828 million people. Patients with diabetes are at risk of several complications including diabetic nephropathy (DN) and metabolic-associated steatohepatitis (MASH). These diseases eventually lead to end stage kidney disease (ESKD) and liver failure requiring dialysis and organ transplantation. In addition, diabetes exacerbates disease severity of autosomal dominant polycystic kidney disease (ADPKD), the most common potentially lethal genetic disease to affect humans with a prevalence of 1 in 500-1000. Therefore, a therapeutic approach that can attenuate organ damage and restore function in patients with DM, …

Glycerol-3-Phosphate Activates Chrebp, Fgf21 Transcription And Lipogenesis In Citrin Deficiency, Vinod Tiwari, Byungchang Jin, Olivia Sun, Edwin D J Lopez Gonzalez, Min-Hsuan Chen, Xiwei Wu, Hardik Shah, Andrew Zhang, Mark A Herman, Cassandra N Spracklen, Russell P Goodman, Charles Brenner

Faculty, Staff and Students Publications

Citrin deficiency (CD) is caused by the inactivation of SLC25A13, a mitochondrial membrane protein required to move electrons from cytosolic NADH to the mitochondrial matrix in hepatocytes. People with CD do not like sweets. Here we show that SLC25A13 loss causes the accumulation of glycerol-3-phosphate (G3P), which activates the carbohydrate response element-binding protein (ChREBP) to transcribe FGF21, which acts in the brain to restrain intake of sweets and alcohol and to transcribe key genes driving lipogenesis. Mouse and human data suggest that G3P-ChREBP is a mechanistic component of the Randle Cycle that contributes to metabolic-dysfunction-associated steatotic liver disease and forms …

Impact Of S-Phase Kinase Protien 2 Blockades On Hematopoetic Stem Cell Metabolism, Nicole Elmaraghy

Electronic Theses, Projects, and Dissertations

Hematopoietic stem and progenitor cells (HSPCs) quiescence is vital for the success of bone marrow transplantation, as it preserves long term self- renewal and prevents premature exhaustion (Takubo et al., 2013; Wilson et al., 2008). However, bone marrow transplant (BMT) failure remains a clinical challenge, often due to lack of long-term engraftment and insufficient stress reliance. Both of these characteristics are tightly linked to disrupted stem cell quiescence and metabolic imbalance (Anso et al., 2017; Vannini et al., 2016). One key player is S-phase kinase protein (SKP2), an E3 ubiquitin ligase that targets cell cycle inhibitors, like p27, for proteosome …

Perineuronal Nets’ Role In Metabolism, Nan Zhang, Beite Song, Peng Bai, Li Du, Lulu Chen, Yong Xu, Tianshu Zeng

Faculty, Staff and Students Publications

Perineuronal nets (PNNs), specialized extracellular matrix (ECM) structures that envelop neurons, have recently been recognized as key players in the regulation of metabolism. This review explores the growing body of knowledge concerning PNNs and their role in metabolic control, drawing insights from recent research and relevant studies. The pivotal role of PNNs in the context of energy balance and whole body blood glucose is examined. This review also highlights novel findings, including the effects of astroglia, microglia, sex and gonadal hormones, nutritional regulation, circadian rhythms, and age on PNNs dynamics. These findings illuminate the complex and multifaceted role of PNNs …

Endothelial-Specific Telomerase Inactivation Causes Telomere-Independent Cell Senescence And Multi-Organ Dysfunction Characteristic Of Aging, Zhanguo Gao, Rafael Bravo Santos, Joseph Rupert, Rachel Van Drunen, Yongmei Yu, Kristin Eckel-Mahan, Mikhail G Kolonin

Faculty, Staff and Student Publications

It has remained unclear how aging of endothelial cells (EC) contributes to pathophysiology of individual organs. Cell senescence results in part from inactivation of telomerase (TERT). Here, we analyzed mice with Tert knockout specifically in EC. Tert loss in EC induced transcriptional changes indicative of senescence and tissue hypoxia in EC and in other cells. We demonstrate that EC-Tert-KO mice have leaky blood vessels. The blood-brain barrier of EC-Tert-KO mice is compromised, and their cognitive function is impaired. EC-Tert-KO mice display reduced muscle endurance and decreased expression of enzymes responsible for oxidative metabolism. Our data indicate that Tert-KO EC have …

Identification Of Novel F2-Isoprostane Metabolites By Specific Udp-Glucuronosyltransferases, Ginger L Milne, Marina S Nogueira, Benlian Gao, Stephanie C Sanchez, Warda Amin, Sarah Thomas, Camille Oger, Jean-Marie Galano, Harvey J Murff, Gong Yang, Thierry Durand

Faculty, Staff and Student Publications

UDP-glucuronosyltransferases (UGTs) catalyze the conjugation of glucuronic acid with endogenous and exogenous lipophilic small molecules to facilitate their inactivation and excretion from the body. This represents approximately 35 % of all phase II metabolic transformations. Fatty acids and their oxidized eicosanoid derivatives can be metabolized by UGTs. F2-isoprostanes (F2-IsoPs) are eicosanoids formed from the free radical oxidation of arachidonic acid. These molecules are potent vasoconstrictors and are widely used as biomarkers of endogenous oxidative damage. An increasing body of evidence demonstrates the efficacy of measuring the β-oxidation metabolites of F2-IsoPs rather than the unmetabolized F2-IsoPs to quantify oxidative damage in …

Obesity And Renal Cell Carcinoma: Biological Mechanisms And Perspectives, Neha Venkatesh, Alberto Martini, Jennifer L Mcquade, Pavlos Msaouel, Andrew W Hahn

Faculty, Staff and Student Publications

Obesity, defined by body mass index (BMI), is an established risk factor for specific renal cell carcinoma (RCC) subtypes such as clear cell RCC, the most common RCC histology. Many studies have identified an association between obesity and improved survival after diagnosis of RCC, a potential "obesity paradox." Clinically, there is uncertainty whether improved outcomes observed after diagnosis are driven by stage, type of treatment received, or artifacts of longitudinal changes in weight and body composition. The biological mechanisms underlying obesity's influence on RCC are not fully established, but multiomic and mechanistic studies suggest an impact on tumor metabolism, particularly …

Development Of Combination Therapy Strategies To Treat Cancer Using Dihydroorotate Dehydrogenase Inhibitors, Nicholas Mullen

Theses & Dissertations

Cancer cells require supraphysiologic levels of nucleotide triphosphates to fuel their malignant behaviors, including uncontrolled proliferation, immune evasion, metastasis, and therapy resistance. This requirement is met by hyperactive flux through the de novo pyrimidine and de novo purine pathways. Dihydroorotate dehydrogenase (DHODH) is an essential enzyme in the de novo pyrimidine pathway that can be targeted by FDA approved and experimental drug compounds. A robust body of preclinical evidence, encompassing hundreds of independent studies over several decades, demonstrates impressive activity of DHODH inhibitors in animal models of cancer. Paradoxically, however, all clinical trials to date have failed to demonstrate efficacy …

Genome-Scale Metabolic Modeling Reveals Sequential Dysregulation Of Glutathione Metabolism In Livers From Patients With Alcoholic Hepatitis, Alexandra Manchel, Radhakrishnan Mahadevan, Ramon Bataller, Jan B. Hoek, Rajanikanth Vadigepalli

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

Alcoholic hepatitis (AH) is the most severe form of alcoholic liver disease for which there is no efficacious treatment aiding most patients. AH manifests differently in individuals, with some patients showing debilitating symptoms more so than others. Previous studies showed significant metabolic dysregulation associated with AH. Therefore, we sought to analyze how the activity of metabolic pathways differed in the liver of patients with varying degrees of AH severity. We utilized a genome-scale metabolic modeling approach that allowed for integration of a generic human cellular metabolic model with specific RNA-seq data corresponding to healthy and multiple liver disease states to …

Evaluation Of Long-Chain Fatty Acid Respiration In Neonatal Mouse Cardiomyocytes Using Seahorse Instrument, Aude Angelini, Xinchun Pi, Liang Xie

Faculty, Staff and Students Publications

Metabolic switches play a critical role in the pathophysiology of cardiac diseases, including heart failure. Here, we describe an assay for long-chain fatty acid oxidation in neonatal mouse cardiomyocytes by using a SeaHorse Flux Analyzer (Agilent). This protocol is a simplified but robust adaptation of the standard protocol that enables metabolic measurements in cells isolated from transgenic mouse models, which can be timesaving and informative. Cell isolation and culture represent a critical point that may require bench optimization.

For complete details on the use and execution of this protocol, please refer to Angelini et al. (2021).

Acute Oxygen-Sensing Via Mitochondria-Generated Temperature Transients In Rat Carotid Body Type I Cells, Ryan J. Rakoczy, Clay M. Schiebrel, Christopher N. Wyatt

Neuroscience, Cell Biology & Physiology Faculty Publications

The Carotid Bodies (CB) are peripheral chemoreceptors that detect changes in arterial oxygenation and, via afferent inputs to the brainstem, correct the pattern of breathing to restore blood gas homeostasis. Herein, preliminary evidence is presented supporting a novel oxygen-sensing hypothesis which suggests CB Type I cell “hypoxic signaling” may in part be mediated by mitochondria-generated thermal transients in TASK-channel-containing microdomains. Distances were measured between antibody-labeled mitochondria and TASK-potassium channels in primary rat CB Type I cells. Sub-micron distance measurements (TASK-1: 0.33 ± 0.04 µm, n = 47 vs TASK-3: 0.32 ± 0.03 µm, n = …

Beth Levine's Legacy: From The Discovery Of Becn1 To Therapies A Mentees' Perspective, Zhenyi An, Wei-Chung Chiang, Álvaro F Fernández, Luis H Franco, Congcong He, Shu-Yi Huang, Eunmyong Lee, Yang Liu, Salwa Sebti, Sanae Shoji-Kawata, Shyam Sirasanagandla, Richard C Wang, Yongjie Wei, Yuting Zhao, Silvia Vega-Rubin-De-Celis

Faculty, Staff and Student Publications

With great sadness, the scientific community received the news of the loss of Beth Levine on 15 June 2020. Dr. Levine was a pioneer in the autophagy field and work in her lab led not only to a better understanding of the molecular mechanisms regulating the pathway, but also its implications in multiple physiological and pathological conditions, including its role in development, host defense, tumorigenesis, aging or metabolism. This review does not aim to provide a comprehensive view of autophagy, but rather an outline of some of the discoveries made by the group of Beth Levine, from the perspective of …

Ethanol And Opioids Do Not Act Synergistically To Depress Excitation In Carotid Body Type I Cells, Ryan J. Rakoczy, Kajal Kamra, Yoon-Jae Yi, Christopher N. Wyatt

Neuroscience, Cell Biology & Physiology Faculty Publications

The combination of opioids and ethanol can synergistically depress breathing and the acute ventilatory response to hypoxia. Multiple studies have shown that the underlying mechanisms for this may involve calcium channel inhibition in central neurons. But we have previously identified opioid receptors in the carotid bodies and shown that their activation inhibits calcium influx into the chemosensitive cells. Given that the carotid bodies contribute to the drive to breathe and underpin the acute hypoxic ventilatory response, we hypothesized that ethanol and opioids may act synergistically in these peripheral sensory organs to further inhibit calcium influx and therefore inhibit ventilation.

Methods …

Aberrant Azin2 And Polyamine Metabolism Precipitates Tau Neuropathology, Leslie A. Sandusky-Beltran, Andrii Kovalenko, Devon S. Placides, Kevin Ratnasamy, Chao Ma, Jerry B. Hunt, Huimin Liang, John Ivan T. Calahatian, Camilla Michalski, Margaret Fahnestock, Laura J. Blair, April L. Darling, Jeremy D. Baker, Sarah N. Fontaine, Chad A. Dickey, Joshua J. Gamsby, Kevin R. Nash, Erin L. Abner, Maj-Linda B. Selenica, Daniel C. Lee

Sanders-Brown Center on Aging Faculty Publications

Tauopathies display a spectrum of phenotypes from cognitive to affective behavioral impairments; however, mechanisms promoting tau pathology and how tau elicits behavioral impairment remain unclear. We report a unique interaction between polyamine metabolism, behavioral impairment, and tau fate. Polyamines are ubiquitous aliphatic molecules that support neuronal function, axonal integrity, and cognitive processing. Transient increases in polyamine metabolism hallmark the cell’s response to various insults, known as the polyamine stress response (PSR). Dysregulation of gene transcripts associated with polyamine metabolism in Alzheimer’s disease (AD) brains were observed, and we found that ornithine decarboxylase antizyme inhibitor 2 (AZIN2) increased to …

Human Retinal Organoids Release Extracellular Vesicles That Regulate Gene Expression In Target Human Retinal Progenitor Cells, Jing Zhou, Miguel Flores‑Bellver, Jianbo Pan, Alberto Benito‑Martin, Cui Shi, Onyekwere Onwumere, Jason Mighty, Jiang Qian, Xiufeng Zhong, Tasmim Hogue, Baffour Amponsah‑Antwi, Linda Einbond, Rajendra Gharbaran, Hao Wu, Bo‑Juen Chen, Zhiliang Zheng, Tatyana Tchaikovskaya, Xusheng Zhang, Hector Peinado, Maria Valeria Canto‑Soler, Stephen Redenti

Publications and Research

The mechanisms underlying retinal development have not been completely elucidated. Extracellular vesicles (EVs) are novel essential mediators of cell‑to‑cell communication with emerging roles in developmental processes. Nevertheless, the identification of EVs in human retinal tissue, characterization of their cargo, and analysis of their potential role in retina development has not been accomplished. Three‑dimensional retinal tissue derived from human induced pluripotent stem cells (hiPSC) provide an ideal developmental system to achieve this goal. Here we report that hiPSC‑derived retinal organoids release exosomes and microvesicles with small noncoding RNA cargo. EV miRNA cargo‑predicted targetome correlates with Gene Ontology (GO) pathways involved in …

Enhancing Glucose Metabolism Via Gluconeogenesis Is Therapeutic In A Zebrafish Model Of Dravet Syndrome, Rajeswari Banerji, Christopher Huynh, Francisco Figueroa, Matthew T Dinday, Scott C Baraban, Manisha Patel

Faculty, Staff and Students Publications

Energy-producing pathways are novel therapeutic targets for the treatment of neurodevelopmental disorders. Here, we focussed on correcting metabolic defects in a catastrophic paediatric epilepsy, Dravet syndrome which is caused by mutations in sodium channel NaV1.1 gene, SCN1A. We utilized a translatable zebrafish model of Dravet syndrome (scn1lab) which exhibits key characteristics of patients with Dravet syndrome and shows metabolic deficits accompanied by down-regulation of gluconeogenesis genes, pck1 and pck2. Using a metabolism-based small library screen, we identified compounds that increased gluconeogenesis via up-regulation of pck1 gene expression in scn1lab larvae. Treatment with PK11195, a pck1 activator …

In Vivo Gene Essentiality And Metabolism In Bordetella Pertussis, Laura A. Gonyar, Patrick E. Gelbach, Dennis G. Mcduffe, Alexander F. Koeppel, Qing Chen, Gloria Lee, Louise M. Temple, Scott Stibitz, Erik L. Hewlwtt, Jason A. Papin, F. Heath Damron, Joshua C. Eby

Faculty & Staff Scholarship

Bordetella pertussis is the causative agent of whooping cough, a serious respiratory illness affecting children and adults, associated with prolonged cough and potential mortality. Whooping cough has reemerged in recent years, emphasizing a need for increased knowledge of basic mechanisms of B. pertussis growth and pathogenicity. While previous studies have provided insight into in vitro gene essentiality of this organism, very little is known about in vivo gene essentiality, a critical gap in knowledge, since B. pertussis has no previously identified environmental reservoir and is isolated from human respiratory tract samples. We hypothesize that the metabolic capabilities of B. pertussis …

Metabolic Regulation Of Cellular Signaling, Rashid John Darbandi

Theses and Dissertations (ETD)

Using the biochemically tractable Xenopus oocyte model system, we have previously characterized a novel metabolic regulation of cell death. We found that glucose-6-phosphate (G6P) via the pentose phosphate pathway leads to increased nicotinamide adenine dinucleotide phosphate (NADPH) levels, a subsequent increase in cytosolic acetyl-coenzyme A and activation of Ca2+/calmodulin-dependent protein kinase II (CaMKII). We recently identified coenzyme A (CoA), derived from the breakdown of acetyl-CoA, as the key metabolic signal that mediates a novel mechanism of calmodulindependent activation of CaMKII. CoA binds directly to the calmodulin (CaM) binding domain (CaMBD) of CaMKII resulting in its activation and downstream inhibitory phosphorylation …

Eisosomes Provide Membrane Reservoirs For Rapid Expansion Of The Yeast Plasma Membrane, Ruth Kabeche, Louisa Howard, James B. Moseley

Dartmouth Scholarship

Cell surface area rapidly increases during mechanical and hypoosmotic stresses. Such expansion of the plasma membrane requires 'membrane reservoirs' that provide surface area and buffer membrane tension, but the sources of this membrane remain poorly understood. In principle, the flattening of invaginations and buds within the plasma membrane could provide this additional surface area, as recently shown for caveolae in animal cells. Here, we used microfluidics to study the rapid expansion of the yeast plasma membrane in protoplasts, which lack the rigid cell wall. To survive hypoosmotic stress, yeast cell protoplasts required eisosomes, protein-based structures that generate long invaginations at …

Stag2 Promotes Error Correction In Mitosis By Regulating Kinetochore–Microtubule Attachments, Marianna Kleyman, Lilian Kabeche, Duane A. Compton

Dartmouth Scholarship

Mutations in the STAG2 gene are present in ∼20% of tumors from different tissues of origin. STAG2 encodes a subunit of the cohesin complex, and tumors with loss-of-function mutations are usually aneuploid and display elevated frequencies of lagging chromosomes during anaphase. Lagging chromosomes are a hallmark of chromosomal instability (CIN) arising from persistent errors in kinetochore-microtubule (kMT) attachment. To determine whether the loss of STAG2 increases the rate of formation of kMT attachment errors or decreases the rate of their correction, we examined mitosis in STAG2-deficient cells. STAG2 depletion does not impair bipolar spindle formation or delay mitotic progression. Instead, …

Novel Roles For Actin In Mitochondrial Fission, Anna L. Hatch, Pinar S. Gurel, Henry N. Higgs

Dartmouth Scholarship

Mitochondrial dynamics, including fusion, fission and translocation, are crucial to cellular homeostasis, with roles in cellular polarity, stress response and apoptosis. Mitochondrial fission has received particular attention, owing to links with several neurodegenerative diseases. A central player in fission is the cytoplasmic dynamin-related GTPase Drp1, which oligomerizes at the fission site and hydrolyzes GTP to drive membrane ingression. Drp1 recruitment to the outer mitochondrial membrane (OMM) is a key regulatory event, which appears to require a pre-constriction step in which the endoplasmic reticulum (ER) and mitochondrion interact extensively, a process termed ERMD (ER-associated mitochondrial division). It is unclear how ER-mitochondrial …

A Pil1–Sle1–Syj1–Tax4 Functional Pathway Links Eisosomes With Pi(4,5)P2 Regulation, Ruth Kabeche, Assen Roguev, Nevan J. Krogan, James B. Moseley

Dartmouth Scholarship

Stable compartments of the plasma membrane promote a wide range of cellular functions. In yeast cells, cytosolic structures called eisosomes generate prominent cortical invaginations of unknown function. Through a series of genetic screens in fission yeast, we found that the eisosome proteins Pil1 and Sle1 function with the synaptojanin-like lipid phosphatase Syj1 and its ligand Tax4. This genetic pathway connects eisosome function with the hydrolysis of phosphatidylinositol (4,5)-bisphosphate [PI(4,5)P2] in cells. Defects in PI(4,5)P2 regulation led to eisosome defects, and we found that the core eisosome protein Pil1 can bind to and tubulate liposomes containing PI(4,5)P2. Mutations in components of …

Inhibition Of The Host Translation Shutoff Response By Herpes Simplex Virus 1 Triggers Nuclear Envelope-Derived Autophagy, Kerstin Radtke, Luc English, Christiane Rondeau, David Leib

Dartmouth Scholarship

Macroautophagy is a cellular pathway that degrades intracellular pathogens and contributes to antigen presentation. Herpes simplex virus 1 (HSV-1) infection triggers both macroautophagy and an additional form of autophagy that uses the nuclear envelope as a source of membrane. The present study constitutes the first in-depth analysis of nuclear envelope-derived autophagy (NEDA). We established LC3a as a marker that allowed us to distinguish between NEDA and macroautophagy in both immunofluorescence and flow cytometry. NEDA was observed in many different cell types, indicating that it is a general response to HSV-1 infection. This autophagic pathway is known to depend on the …

Scfslimb Ubiquitin Ligase Suppresses Condensin Ii–Mediated Nuclear Reorganization By Degrading Cap-H2, Daniel W. Buster, Scott G. Daniel, Huy Q. Nguyen, Sarah L. Windler, Lara C. Skwarek, Maureen Peterson

Dartmouth Scholarship

Condensin complexes play vital roles in chromosome condensation during mitosis and meiosis. Condensin II uniquely localizes to chromatin throughout the cell cycle and, in addition to its mitotic duties, modulates chromosome organization and gene expression during interphase. Mitotic condensin activity is regulated by phosphorylation, but mechanisms that regulate condensin II during interphase are unclear. Here, we report that condensin II is inactivated when its subunit Cap-H2 is targeted for degradation by the SCF(Slimb) ubiquitin ligase complex and that disruption of this process dramatically changed interphase chromatin organization. Inhibition of SCF(Slimb) function reorganized interphase chromosomes into dense, compact domains and disrupted …

Regulation Of Lipogenesis By Cyclin-Dependent Kinase 8-Mediated Control Of Srebp-1., Xiaoping Zhao, Daorong Feng, Qun Wang, Arian Abdulla, Xiao-Jun Xie, Jie Zhou, Yan Sun, Ellen S Yang, Lu-Ping Liu, Bhavapriya Vaitheesvaran, Lauren Bridges, Irwin J Kurland, Randy Strich, Jian-Quan Ni, Chenguang Wang, Johan Ericsson, Jeffrey E Pessin, Jun-Yuan Ji, Fajun Yang

Department of Cancer Biology Faculty Papers

Altered lipid metabolism underlies several major human diseases, including obesity and type 2 diabetes. However, lipid metabolism pathophysiology remains poorly understood at the molecular level. Insulin is the primary stimulator of hepatic lipogenesis through activation of the SREBP-1c transcription factor. Here we identified cyclin-dependent kinase 8 (CDK8) and its regulatory partner cyclin C (CycC) as negative regulators of the lipogenic pathway in Drosophila, mammalian hepatocytes, and mouse liver. The inhibitory effect of CDK8 and CycC on de novo lipogenesis was mediated through CDK8 phosphorylation of nuclear SREBP-1c at a conserved threonine residue. Phosphorylation by CDK8 enhanced SREBP-1c ubiquitination and protein …

Pv1 Down-Regulation Via Shrna Inhibits The Growth Of Pancreatic Adenocarcinoma Xenografts, Sophie J. Deharvengt, Dan Tse, Olga Sideleva, Caitlin Mcgarry, Jason R. Gunn, Daniel S. Longnecker, Catherine Carriere, Radu V. Stan

Dartmouth Scholarship

PV1 is an endothelial-specific protein with structural roles in the formation of diaphragms in endothelial cells of normal vessels. PV1 is also highly expressed on endothelial cells of many solid tumours. On the basis of in vitro data, PV1 is thought to actively participate in angiogenesis. To test whether or not PV1 has a function in tumour angiogenesis and in tumour growth in vivo, we have treated pancreatic tumour-bearing mice by single-dose intratumoural delivery of lentiviruses encoding for two different shRNAs targeting murine PV1. We find that PV1 down-regulation by shRNAs inhibits the growth of established tumours derived from two …

Seg1 Controls Eisosome Assembly And Shape, Karen E. Moreira, Sebastian Schuck, Bianca Schrul, Florian Fröhlich, James B. Moseley

Dartmouth Scholarship

Eisosomes are stable domains at the plasma membrane of the budding yeast Saccharomyces cerevisiae and have been proposed to function in endocytosis. Eisosomes are composed of two main cytoplasmic proteins, Pil1 and Lsp1, that form a scaffold around furrow-like plasma membrane invaginations. We show here that the poorly characterized eisosome protein Seg1/Ymr086w is important for eisosome biogenesis and architecture. Seg1 was required for efficient incorporation of Pil1 into eisosomes and the generation of normal plasma membrane furrows. Seg1 preceded Pil1 during eisosome formation and established a platform for the assembly of other eisosome components. This platform was further shaped and …

Chromosome Missegregation In Human Cells Arises Through Specific Types Of Kinetochore–Microtubule Attachment Errors, Sarah L. Thompson, Duane A. Compton

Dartmouth Scholarship

Most solid tumors are aneuploid, and many missegregate chromosomes at high rates in a phenomenon called chromosomal instability (CIN). CIN reflects the erosion of mitotic fidelity, and it correlates with poor patient prognosis and drug resistance. The most common mechanism causing CIN is the persistence of improper kinetochore–microtubule attachments called merotely. Chromosomes with merotelic kinetochores often manifest as lagging chromosomes in anaphase, suggesting that lagging chromosomes fail to segregate properly. However, it remains unknown whether the lagging chromosomes observed in anaphase segregate to the correct or incorrect daughter cell. To address this question, we tracked the segregation of a single …

Mediator Influences Telomeric Silencing And Cellular Life Span, Xuefeng Zhu, Beidong Liu, Jonas O. P. Carlsten, Jenny Beve, Thomas Nyström, Lawrence C. Myers, Claes M. Gustafsson

Dartmouth Scholarship

The Mediator complex is required for the regulated transcription of nearly all RNA polymerase II-dependent genes. Here we demonstrate a new role for Mediator which appears to be separate from its function as a transcriptional coactivator. Mediator associates directly with heterochromatin at telomeres and influences the exact boundary between active and inactive chromatin. Loss of the Mediator Med5 subunit or mutations in Med7 cause a depletion of the complex from regions located near subtelomeric X elements, which leads to a change in the balance between the Sir2 and Sas2 proteins. These changes in turn result in increased levels of H4K16 …

Carhsp1 Is Required For Effective Tumor Necrosis Factor Alpha Mrna Stabilization And Localizes To Processing Bodies And Exosomes, Jason R. Pfeiffer, Bethany L. Mcavoy, Ryan E. Fecteau, Kristen M. Deleault, Seth A. Brooks

Dartmouth Scholarship

Tumor necrosis factor alpha (TNF-α) is a critical mediator of inflammation, and its production is tightly regulated, with control points operating at nearly every step of its biosynthesis. We sought to identify uncharacterized TNF-α 3' untranslated region (3'UTR)-interacting proteins utilizing a novel screen, termed the RNA capture assay. We identified CARHSP1, a cold-shock domain-containing protein. Knockdown of CARHSP1 inhibits TNF-α protein production in lipopolysaccharide (LPS)-stimulated cells and reduces the level of TNF-α mRNA in both resting and LPS-stimulated cells. mRNA stability assays demonstrate that CARHSP1 knockdown decreases TNF-α mRNA stability from a half-life (t(1/2)) of 49 min to a t(1/2) …