Medicine and Health Sciences Commons^™

Multiple Autonomous Cell Death Suppression Strategies Ensure Cytomegalovirus Fitness, Pratyusha Mandal, Lynsey Nagrani, Liliana Hernandez, Anita Louise Mccormick, Christopher Dillon, Heather Koehler, Linda Roback, Emad S Alnemri, Douglas Green, Edward Mocarski

Department of Biochemistry and Molecular Biology Faculty Papers

Programmed cell death pathways eliminate infected cells and regulate infection-associated inflammation during pathogen invasion. Cytomegaloviruses encode several distinct suppressors that block intrinsic apoptosis, extrinsic apoptosis, and necroptosis, pathways that impact pathogenesis of this ubiquitous herpesvirus. Here, we expanded the understanding of three cell autonomous suppression mechanisms on which murine cytomegalovirus relies: (i) M38.5-encoded viral mitochon-drial inhibitor of apoptosis (vMIA), a BAX suppressor that functions in concert with M41.1-encoded viral inhibitor of BAK oligomerization (vIBO), (ii) M36-encoded viral inhibitor of caspase-8 activation (vICA), and (iii) M45-encoded viral inhibitor of RIP/RHIM activation (vIRA). Following infection of bone marrow-derived macrophages, the virus initially …

Distinct Mechanisms Control Genome Recognition By P53 At Its Target Genes Linked To Different Cell Fates., Marina Farkas, Hideharu Hashimoto, Yingtao Bi, Ramana V Davuluri, Lois Resnick-Silverman, James J. Manfredi, Erik W. Debler, Steven B. Mcmahon

Department of Biochemistry and Molecular Biology Faculty Papers

The tumor suppressor p53 integrates stress response pathways by selectively engaging one of several potential transcriptomes, thereby triggering cell fate decisions (e.g., cell cycle arrest, apoptosis). Foundational to this process is the binding of tetrameric p53 to 20-bp response elements (REs) in the genome (RRRCWWGYYYN_0-13RRRCWWGYYY). In general, REs at cell cycle arrest targets (e.g. p21) are of higher affinity than those at apoptosis targets (e.g., BAX). However, the RE sequence code underlying selectivity remains undeciphered. Here, we identify molecular mechanisms mediating p53 binding to high- and low-affinity REs by showing that key determinants of the code are embedded …

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 …

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 …

Regulation Of Cell Death By Transfer Rna., Ya-Ming Hou, Xiaolu Yang

Department of Biochemistry and Molecular Biology Faculty Papers

SIGNIFICANCE: Both transfer RNA (tRNA) and cytochrome c are essential molecules for the survival of cells. tRNA decodes mRNA codons into amino-acid-building blocks in protein in all organisms, whereas cytochrome c functions in the electron transport chain that powers ATP synthesis in mitochondrion-containing eukaryotes. Additionally, in vertebrates, cytochrome c that is released from mitochondria is a potent inducer of apoptosis, activating apoptotic proteins (caspases) in the cytoplasm to dismantle cells. A better understanding of both tRNA and cytochrome c is essential for an insight into the regulation of cell life and death.

RECENT ADVANCES: A recent study showed that the …

Evaluation Of Glucocorticoid Sensitivity In 697 Pre-B Acute Lymphoblastic Leukemia Cells After Overexpression Or Silencing Of Map Kinase Phosphotase-1, Marc T. Abrams, Noreen Robertson, Gerald Litwack, Eric Wickstrom

Department of Biochemistry and Molecular Biology Faculty Papers

PURPOSE: To determine the effect of reducing MAP kinase phosphatase-1 (MKP-1) levels on cell death induced by glucocorticoid (GC) or hydroxyurea (HU) treatment in the human pre-B acute lymphoblastic leukemia cell line 697.

METHODS: Stable MKP-1 overexpressing transformants of the 697 pre-B ALL cell line were created and tested for sensitivity to the GC triamcinolone acetonide (TA) and HU, and compared to a control 697 cell line containing normal MKP-1 expression levels. Small interfering RNAs (siRNAs) were designed to inhibit MKP-1 expression and evaluated for their effect on GC-mediated cell death.

RESULTS: MKP-1 overexpression caused a phenotype of partial resistance …

Inhibition Of Glucocorticoid-Induced Apoptosis By Targeting Splice Variants Of Bim Mrna With Small Interfering Rna And Short Hairpin Rna., Marc T. Abrams, Noreen M. Robertson, Kyonggeun Yoon, Eric Wickstrom

Department of Biochemistry and Molecular Biology Faculty Papers

Glucocorticoids (GCs) induce apoptosis in lymphocytes and are effective agents for the treatment of leukemia. The activated glucocorticoid receptor (GR) initiates a transcriptional program leading to caspase activation and cell death, but the critical signaling intermediates in GC-induced apoptosis remain largely undefined. We have observed that GC induction of the three major protein products of the Bcl-2 relative Bim (BimEL, BimS and BimL) correlates with GC sensitivity in a panel of human pre-B acute lymphoblastic leukemia (ALL) cell lines. To test the hypothesis that Bim facilitates GC-induced apoptosis, we reduced BIM mRNA levels and Bim protein levels by RNA interference …