Proteomic analysis reveals USP7 as a novel regulator of palmitic acid-induced hepatocellular carcinoma cell death

Abstract

Nutrient surplus and consequent free fatty acid accumulation in the liver cause hepatosteatosis. The exposure of free fatty acids to cultured hepatocyte and hepatocellular carcinoma cell lines induces cellular stress, organelle adaptation, and subsequent cell death. Despite many studies, the mechanism associated with lipotoxicity and subsequent cell death still remains poorly understood. Here, we have used the proteomics approach to circumvent the mechanism for lipotoxicity using hepatocellular carcinoma cells as a model. Our quantitative proteomics data revealed that ectopic lipids accumulation in cells severely affects the ubiquitin-proteasomal system. The palmitic acid (PA) partially lowered the expression of deubiquitinating enzyme USP7 which subsequently destabilizes p53 and promotes mitotic entry of cells. Our global phosphoproteomics analysis also provides strong evidence of an altered cell cycle checkpoint proteins’ expression that abrogates early G2/M checkpoints recovery with damaged DNA and induced mitotic catastrophe leading to hepatocyte death. We observe that palmitic acid prefers apoptosis-inducing factor (AIF) mediated cell death by depolarizing mitochondria and translocating AIF to the nucleus. In summary, the present study provides evidence of PA-induced hepatocellular death mediated by deubiquitinase USP7 downregulation and subsequent mitotic catastrophe.

A Combination of Four Nuclear Targeted Effectors ProtectsToxoplasmaAgainst Interferon Gamma Driven Human Host Cell Death During Acute Infection

“…GRA16 alters p53 levels through an interaction with Ubiquitin Specific Peptidase 7 (USP7/HAUSP). Considering GRA16's limited impact on IFNγ driven transcription, its significance may lie in its influence on host cell death pathways regulated by p53 (76). Alternatively, many of the target genes that are immediately induced by IFNγ/STAT1 signaling are transcription factors such as interferon response factor 1 (IRF1), IRF9 and others that then drive the expression of secondary response genes (77) promoters of which lack functional GAS elements.…”

Elevated glycosylation of CD36 in platelets is a risk factor for oxLDL‐mediated platelet activation in type 2 diabetes

“…The peptides were separated using a 45‐min gradient with a total run time of 60 min at a flow rate of 250 nL·min −1 . The MS data of each condition was acquired in information‐dependent acquisition mode [35].…”

“…Carbamidomethyl (C), deamidation (NQ), oxidation (M) and Asn→ Asp were set as variable modifications. Peptides and proteins were filtered at a 1% false discovery rate [35]. Protein quantifications were performed based on the precursor intensity.…”

Inhibition of Hepatocellular Carcinoma by Endogenous Lipids: Induction of Pyroptosis by Geranylgeranoic Acid—A Comparison with Palmitic Acid and Retinoic Acid

“…The final concentrations of PA added to the medium range from 200 to 3000 µM, which is 10 to several hundred times higher than GGA or ATRA. Although there are many reports, cell death is confirmed within 24 h after PA treatment [11,12,[43][44][45][46]. Molecules that exert effects at concentrations of several µM like GGA or ATRA are thought to act as signaling molecules.…”