Biochemistry, Biophysics, and Structural Biology Commons^™

Beclin-1 Expression Is Retained In High-Grade Serous Ovarian Cancer Yet Is Not Essential For Autophagy Induction In Vitro, Rohann J. M. Correa, Yudith Ramos Valdes, Trevor G. Shepherd, Gabriel E. Dimattia

Biochemistry Publications

BACKGROUND: Autophagy is a conserved cellular self-digestion mechanism that can either suppress or promote cancer in a context-dependent manner. In ovarian cancer, prevalent mono-allelic deletion of BECN1 (a canonical autophagy-inducer) suggests that autophagy is impaired to promote carcinogenesis and that Beclin-1 is a haploinsufficient tumor suppressor. Nonetheless, autophagy is known to be readily inducible in ovarian cancer cells. We sought to clarify whether Beclin-1 expression is in fact disrupted in ovarian cancer and whether this impacts autophagy regulation.

METHODS: BECN1 expression levels were assessed using The Cancer Genome Atlas (TCGA) datasets from 398 ovarian high-grade serous cystadenocarcinomas (HGSC) and protein …

Structural Analysis Of The 14-3-3Ζ/Chibby Interaction Involved In Wnt/Β-Catenin Signaling, Ryan C Killoran, Jingsong Fan, Daiwen Yang, Brian H Shilton, Wing-Yiu Choy

Biochemistry Publications

The partially disordered Chibby (Cby) is a conserved nuclear protein that antagonizes the Wnt/β-catenin signaling pathway. By competing with the Tcf/Lef family proteins for binding to β-catenin, Cby abrogates the β-catenin-mediated transcription of Wnt signaling genes. Additionally, upon phosphorylation on S20 by the kinase Akt, Cby forms a complex with 14-3-3 to facilitate the nuclear export of β-catenin, which represents another crucial mechanism for the regulation of Wnt signaling. To obtain a mechanistic understanding of the 14-3-3/Cby interaction, we have extensively characterized the complex using X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, and isothermal titration calorimetry (ITC). The crystal structure …

Molecular Effects Of Cancer-Associated Somatic Mutations On The Structural And Target Recognition Properties Of Keap1., Halema Khan, Ryan C Killoran, Anne Brickenden, Jingsong Fan, Daiwen Yang, Wing-Yiu Choy

Biochemistry Publications

Kelch-like ECH-associated protein 1 (Keap1) plays an important regulatory role in the nuclear factor erythroid 2-related factor 2 (Nrf2)-dependent oxidative stress response pathway. It functions as a repressor of Nrf2, a key transcription factor that initiates the expression of cytoprotective enzymes during oxidative stress to protect cells from damage caused by reactive oxygen species. Recent studies show that mutations of Keap1 can lead to aberrant activation of the antioxidant pathway, which is associated with different types of cancers. To gain a mechanistic understanding of the links between Keap1 mutations and cancer pathogenesis, we have investigated the molecular effects of a …

Characterization Of Ranbpm Molecular Determinants That Control Its Subcellular Localization, Louisa M Salemi, Sandra O Loureiro, Caroline Schild-Poulter

Biochemistry Publications

RanBPM/RanBP9 is a ubiquitous, nucleocytoplasmic protein that is part of an evolutionary conserved E3 ubiquitin ligase complex whose function and targets in mammals are still unknown. RanBPM itself has been implicated in various cellular processes that involve both nuclear and cytoplasmic functions. However, to date, little is known about how RanBPM subcellular localization is regulated. We have conducted a systematic analysis of RanBPM regions that control its subcellular localization using RanBPM shRNA cells to examine ectopic RanBPM mutant subcellular localization without interference from the endogenously expressed protein. We show that several domains and motifs regulate RanBPM nuclear and cytoplasmic localization. …

Reversing Chromatin Accessibility Differences That Distinguish Homologous Mitotic Metaphase Chromosomes., Wahab A Khan, Peter K Rogan, Joan H M Knoll

Biochemistry Publications

BACKGROUND: Chromatin-modifying reagents that alter histone associating proteins, DNA conformation or its sequence are well established strategies for studying chromatin structure in interphase (G1, S, G2). Little is known about how these compounds act during metaphase. We assessed the effects of these reagents at genomic loci that show reproducible, non-random differences in accessibility to chromatin that distinguish homologous targets by single copy DNA probe fluorescence in situ hybridization (scFISH). By super-resolution 3-D structured illumination microscopy (3D-SIM) and other criteria, the differences correspond to 'differential accessibility' (DA) to these chromosomal regions. At these chromosomal loci, DA of the same homologous chromosome …