Dataset Information

HCV Hypo- vs. Hyper-Phosphorylated NS5A Interactome

ABSTRACT: Chronic hepatitis C virus (HCV) infection is a leading cause of liver cancer. HCV propagation and oncogenicity depend in part on the phosphorylation states of its non-structural protein 5A (NS5A); however, little is known about how hypo- or hyper-phosphorylated NS5A functions. Here, we segregated hypo- from hyper-phosphorylated NS5A in HCV-infected Huh7.5.1 cells with two custom-made specific antibodies and differentiated their interacting proteins with dimethyl labeling-based quantitative proteomics. Bioinformatics analysis revealed that hyper-phosphorylated NS5A preferentially binds the polymerase II-associated factor 1 complex known to alter host gene expression involved in cancer progression. In contrast, hypo-phosphorylated NS5A binds proteins involved in host antiviral response. Moreover, we found that the hypo-phosphorylated NS5A binds DNA-dependent protein kinase catalytic subunit (DNA-PKcs) predicted to phosphorylate NS5A at serine 232, a key amino acid that governs NS5A transition from hypo- to hyper-phosphorylation state. Inhibition of DNA-PKcs with an inhibitor or via gene-specific knockdown significantly reduced serine 232 phosphorylation and NS5A hyper-phosphorylation. Collectively, we have identified a protein kinase that regulates a delicate balance of NS5A between hypo- and hyper-phosphorylation states respectively involved in host antiviral responses and liver cancer progression.

INSTRUMENT(S): LTQ Orbitrap Velos

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Hepatocyte, Cell Culture

DISEASE(S): Hepatocellular Carcinoma

SUBMITTER: Ming-Jiun Yu

LAB HEAD: Ming-Jiun Yu

PROVIDER: PXD012767 | Pride | 2019-06-17

REPOSITORIES: Pride

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Publications

Differential Proteomics Reveals Discrete Functions of Proteins Interacting with Hypo- versus Hyper-phosphorylated NS5A of the Hepatitis C Virus.

Pan Ting-Chun TC Lo Chieh-Wen CW Chong Weng Man WM Tsai Chia-Ni CN Lee Kuan-Ying KY Chen Pin-Yin PY Liao Jung-Chi JC Yu Ming-Jiun MJ

Journal of proteome research 20190621 7

Protein phosphorylation is a reversible post-translational modification that regulates many biological processes in almost all living forms. In the case of the hepatitis C virus (HCV), the nonstructural protein 5A (NS5A) is believed to transit between hypo- and hyper-phosphorylated forms that interact with host proteins to execute different functions; however, little was known about the proteins that bind either form of NS5A. Here, we generated two high-quality antibodies specific to serine 235 ...[more]

PMID: 31199160

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Project description:The retinoblastoma tumor suppressor protein (Rb) regulates early G1 phase checkpoints, including the DNA damage response, as well as cell cycle exit and differentiation. The widely accepted model of G1 cell cycle progression proposes that cyclin D:Cdk4/6 partially inactivates the Rb tumor suppressor during early G1 phase by progressive multi-phosphorylation, termed hypo-phosphorylation, resulting in release of E2F transcription factors. However, this model remains largely unproven biochemically and the biologically active form(s) of Rb remains unknown. Here we find that Rb is un-phosphorylated in G0 cells and becomes exclusively mono-phosphorylated throughout all of early G1 phase by cyclin D:Cdk4/6. Early G1 phase mono-phosphorylated Rb is composed of 14 independent isoforms that are all targeted by the E1a oncoprotein, but each shows a preferential binding pattern to specific E2F1-4 transcription factors. At the late G1 Restriction Point, cyclin E:Cdk2 inactivates Rb by a quantum hyper-phosphorylation (>12 phosphates/Rb). Cells undergoing a DNA damage response activate cyclin D:Cdk4/6 to generate mono-phosphorylated Rb that regulates global transcription. In contrast, a non-phosphorylatable ?Cdk-Rb allele was non-functional for regulating a DNA damage response, but functional for driving cell cycle exit and differentiation during myogenesis. These observations fundamentally change our understanding of G1 cell cycle progression and show that there is no progressive multi-phosphorylation or hypo-phosphorylation inactivation of Rb during early G1 phase by cyclin D:Cdk4/6. Instead, cyclin D:Cdk4/6 generates functionally active, mono-phosphorylated Rb that is the only Rb isoform present in cells during early G1 phase. Global transcriptional analysis of murine embryonic fibroblasts (MEFs) with conditional deletion of the endogenous RB gene by treatment with cell permeable TAT-Cre. Comparison to unaltered MEFs and MEFs with physiological level of exogenous wildtype or phospho-mutant RB expressed at time of RB gene deletion.

Dataset Information

HCV Hypo- vs. Hyper-Phosphorylated NS5A Interactome

Publications

Differential Proteomics Reveals Discrete Functions of Proteins Interacting with Hypo- versus Hyper-phosphorylated NS5A of the Hepatitis C Virus.

Similar Datasets

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