Biochemistry, Biophysics, and Structural Biology | Open Access Articles

A Cytosolic Multiprotein Complex Containing P85Α Is Required For Β-Catenin Activation In Colitis And Colitis-Associated Cancer, Tatiana Goretsky, Emily M. Bradford, Hyunji Ryu, Maryam Tahir, Mary Pat Moyer, Tianyan Gao, Linheng Li, Terrence A. Barrett

Internal Medicine Faculty Publications

Wnt/β-catenin signaling is required for crypt structure maintenance. We previously observed nuclear accumulation of Ser-552 phosphorylated β-catenin (pβ-Cat^Ser-552) in intestinal epithelial cells (IEC) during colitis and colitis-associated cancer. Data here delineate a novel multiprotein cytosolic complex (MCC) involved in β-catenin signaling in the intestine. The MCC contains p85α, the class IA subunit of PI3K, along with β-catenin, 14-3-3ζ, Akt, and p110α. MCC levels in IEC increase in colitis and colitis-associated cancer patients. IEC-specific p85α-deficient (p85^ΔIEC) mice develop more severe dextran sodium …

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Autophagy Is Induced Upon Platelet Activation And Is Essential For Hemostasis And Thrombosis, Madhu M. Ouseph, Yunjie Huang, Meenakshi Banerjee, Smita Joshi, Laura Macdonald, Yu Zhong, Huijuan Liu, Xianting Li, Binggang Xiang, Guoying Zhang, Masaaki Komatsu, Zhenyu Yue, Zhenyu Li, Brian Storrie, Sidney W. Whiteheart, Qing Jun Wang

Molecular and Cellular Biochemistry Faculty Publications

Autophagy is important for maintaining cellular homeostasis, and thus its deficiency is implicated in a broad spectrum of human diseases. Its role in platelet function has only recently been examined. Our biochemical and imaging studies demonstrate that the core autophagy machinery exists in platelets, and that autophagy is constitutively active in resting platelets. Moreover, autophagy is induced upon platelet activation, as indicated by agonist-induced loss of the autophagy marker LC3II. Additional experiments, using inhibitors of platelet activation, proteases, and lysosomal acidification, as well as platelets from knockout mouse strains, show that agonist-induced LC3II loss is a consequence of platelet signaling …

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Proteasome-Mediated Proteolysis Of The Polyglutamine-Expanded Androgen Receptor Is A Late Event In Spinal And Bulbar Muscular Atrophy (Sbma) Pathogenesis., Erin M Heine, Tamar R Berger, Anna Pluciennik, Christopher R Orr, Lori Zboray, Diane E Merry

Department of Biochemistry and Molecular Biology Faculty Papers

Proteolysis of polyglutamine-expanded proteins is thought to be a required step in the pathogenesis of several neurodegenerative diseases. The accepted view for many polyglutamine proteins is that proteolysis of the mutant protein produces a "toxic fragment" that induces neuronal dysfunction and death in a soluble form; toxicity of the fragment is buffered by its incorporation into amyloid-like inclusions. In contrast to this view, we show that, in the polyglutamine disease spinal and bulbar muscular atrophy, proteolysis of the mutant androgen receptor (AR) is a late event. Immunocytochemical and biochemical analyses revealed that the mutant AR aggregates as a full-length protein, …

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Transcriptional Activity Of The Islet Β Cell Factor Pdx1 Is Augmented By Lysine Methylation Catalyzed By The Methyltransferase Set7/9, Aarthi V. Maganti, Bernhard Maier, Sarah A. Tersey, Megan L. Sampley, Amber L. Mosley, Sabire Özcan, Boobalan Pachaiyappan, Patrick M. Woster, Chad S. Hunter, Roland Stein, Raghavendra G. Mirmira

Molecular and Cellular Biochemistry Faculty Publications

The transcription factor Pdx1 is crucial to islet β cell function and regulates target genes in part through interaction with coregulatory factors. Set7/9 is a Lys methyltransferase that interacts with Pdx1. Here we tested the hypothesis that Lys methylation of Pdx1 by Set7/9 augments Pdx1 transcriptional activity. Using mass spectrometry and mutational analysis of purified proteins, we found that Set7/9 methylates the N-terminal residues Lys-123 and Lys-131 of Pdx1. Methylation of these residues occurred only in the context of intact, full-length Pdx1, suggesting a specific requirement of secondary and/or tertiary structural elements for catalysis by Set7/9. Immunoprecipitation assays and mass …

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Trail-Based High Throughput Screening Reveals A Link Between Trail-Mediated Apoptosis And Glutathione Reductase, A Key Component Of Oxidative Stress Response., Dmitri Rozanov, Anton Cheltsov, Eduard Sergienko, Stefan Vasile, Vladislav Golubkov, Alexander E Aleshin, Trevor Levin, Elie Traer, Byron Hann, Julia Freimuth, Nikita Alexeev, Max A Alekseyev, Sergey P Budko, Hans Peter Bächinger, Paul Spellman

Computational Biology Institute

A high throughput screen for compounds that induce TRAIL-mediated apoptosis identified ML100 as an active chemical probe, which potentiated TRAIL activity in prostate carcinoma PPC-1 and melanoma MDA-MB-435 cells. Follow-up in silico modeling and profiling in cell-based assays allowed us to identify NSC130362, pharmacophore analog of ML100 that induced 65-95% cytotoxicity in cancer cells and did not affect the viability of human primary hepatocytes. In agreement with the activation of the apoptotic pathway, both ML100 and NSC130362 synergistically with TRAIL induced caspase-3/7 activity in MDA-MB-435 cells. Subsequent affinity chromatography and inhibition studies convincingly demonstrated that glutathione reductase (GSR), a key …

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Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

A Cytosolic Multiprotein Complex Containing P85Α Is Required For Β-Catenin Activation In Colitis And Colitis-Associated Cancer, Tatiana Goretsky, Emily M. Bradford, Hyunji Ryu, Maryam Tahir, Mary Pat Moyer, Tianyan Gao, Linheng Li, Terrence A. Barrett

Internal Medicine Faculty Publications

Molecular and Cellular Biochemistry Faculty Publications

Proteasome-Mediated Proteolysis Of The Polyglutamine-Expanded Androgen Receptor Is A Late Event In Spinal And Bulbar Muscular Atrophy (Sbma) Pathogenesis., Erin M Heine, Tamar R Berger, Anna Pluciennik, Christopher R Orr, Lori Zboray, Diane E Merry

Department of Biochemistry and Molecular Biology Faculty Papers

Molecular and Cellular Biochemistry Faculty Publications

Computational Biology Institute