Adenosine triphosphatase pontin is overexpressed in hepatocellular carcinoma and coregulated with reptin through a new posttranslational mechanism†

Haurie, Valérie; Ménard, Ludovic; Nicou, Alexandra; Touriol, Christian; Metzler, Philippe; Fernandez, Jérémy; Taras, Danièle; Lestienne, Patrick; Balabaud, Charles; Bioulac‐Sage, Paulette; Prats, Hervé; Zucman‐Rossi, Jessica; Rosenbaum, Jean

doi:10.1002/hep.23215

Cited by 57 publications

(81 citation statements)

References 36 publications

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“…With the aim of determining the role of Reptin ATPase activity in hepatocellular carcinoma cell growth, we first expressed the ATPase dead mutant D299N in the presence of endogenous Reptin, using lentiviral vectors. In agreement with our previous results showing a tight posttranslational control of Reptin expression (20), this strategy did not allow for an overexpression of Flag-tagged Reptin, either WT or mutated. Indeed, the total amount of Reptin was similar between the 3 conditions, with Flag-tagged Reptin representing approximately 50% of the total amount in transduced cells (Fig.…”

Section: Expression Of a Reptin Atpase-dead Mutant Impairs Hepatocellsupporting

confidence: 91%

“…Reptin mutants retained the same subcellular distribution as WT Reptin, and also their ability to partner with Pontin, suggesting that they had no gross defects besides the loss of ATPase activity that could explain their phenotypic effects. We and others have previously shown that Reptin silencing induced the codepletion of Pontin, via a posttranslational mechanism (4,7,20). However, we show here that cells reconstituted with the Reptin Walker B mutants expressed normal levels of Pontin such as those reconstituted with WT siRNA-resistant Reptin (20), thus ruling out that some of the effects seen with the mutants might be due to the loss of Pontin.…”

Section: Discussioncontrasting

confidence: 66%

“…We and others have previously shown that Reptin silencing induced the codepletion of Pontin, via a posttranslational mechanism (4,7,20). However, we show here that cells reconstituted with the Reptin Walker B mutants expressed normal levels of Pontin such as those reconstituted with WT siRNA-resistant Reptin (20), thus ruling out that some of the effects seen with the mutants might be due to the loss of Pontin. Although the issue is not completely settled, the most recent evidence suggests that human Reptin and Pontin are organized in heterohexamers (24)(25)(26).…”

Section: Discussioncontrasting

confidence: 66%

“…2A and B). We previously showed that Reptin silencing led to a codepletion of Pontin through a posttranslational mechanism (20). Here, we show that substitution of endogenous Reptin with siRNA-resistant Flag-tagged Reptin preserved Pontin expression, whether Reptin was WT or D299N ( Fig.…”

Section: Expression Of a Reptin Atpase-dead Mutant Impairs Hepatocellsupporting

confidence: 59%

“…Western blot was done as described previously (20). All blots were analyzed with the Odyssey system (Li-Cor Biosciences).…”

Section: Western Blot and Immunoprecipitationmentioning

confidence: 99%

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The ATPase Activity of Reptin Is Required for Its Effects on Tumor Cell Growth and Viability in Hepatocellular Carcinoma

Grigoletto

Neaud

Allain-Courtois

et al. 2013

Molecular Cancer Research

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Reptin is overexpressed in most human hepatocellular carcinomas. Reptin is involved in chromatin remodeling, transcription regulation, or supramolecular complexes assembly. Its silencing leads to growth arrest and apoptosis in cultured hepatocellular carcinoma cells and stops hepatocellular carcinoma progression in xenografts. Reptin has an ATPase activity linked to Walker A and B domains. It is unclear whether every Reptin function depends on its ATPase activity. Here, we expressed Walker B ATPase-dead mutants (D299N or E300G) in hepatocellular carcinoma cells in the presence of endogenous Reptin. Then, we silenced endogenous Reptin and substituted it with siRNA-resistant wild-type (WT) or Flag-Reptin mutants. There was a significant decrease in cell growth when expressing either mutant in the presence of endogenous Reptin, revealing a dominant negative effect of the ATPase dead mutants on hepatocellular carcinoma cell growth. Substitution of endogenous Reptin by WT Flag-Reptin rescued cell growth of HuH7. On the other hand, substitution by Flag-Reptin D299N or E300G led to cell growth arrest. Similar results were seen with Hep3B cells. Reptin silencing in HuH7 cells led to an increased apoptotic cell death, which was prevented by WT Flag-Reptin but not by the D299N mutant. These data show that Reptin functions relevant for cancer are dependent on its ATPase activity, and suggest that antagonists of Reptin

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Section: Expression Of a Reptin Atpase-dead Mutant Impairs Hepatocellsupporting

confidence: 91%

Section: Discussioncontrasting

confidence: 66%

Section: Discussioncontrasting

confidence: 66%

Section: Expression Of a Reptin Atpase-dead Mutant Impairs Hepatocellsupporting

confidence: 59%

“…Western blot was done as described previously (20). All blots were analyzed with the Odyssey system (Li-Cor Biosciences).…”

Section: Western Blot and Immunoprecipitationmentioning

confidence: 99%

See 3 more Smart Citations

The ATPase Activity of Reptin Is Required for Its Effects on Tumor Cell Growth and Viability in Hepatocellular Carcinoma

Grigoletto

Neaud

Allain-Courtois

et al. 2013

Molecular Cancer Research

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Reptin regulates insulin‐stimulated Akt phosphorylation in hepatocellular carcinoma via the regulation of SHP‐1/PTPN6

Raymond

Javary

Breig

et al. 2017

Cell Biochemistry & Function

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Hepatocellular carcinoma (HCC) is the main primary cancer of the liver. Many studies have shown that insulin resistance is a risk factor for HCC. We previously discovered the overexpression and oncogenic role of the Reptin/RUVBL2 ATPase in HCC. Here, we found that Reptin silencing enhanced insulin sensitivity in 2 HCC cell lines, as shown by a large potentiation of insulin-induced AKT phosphorylation on Ser473 and Thr308, and of downstream signalling. Reptin silencing did not affect the tyrosine phosphorylation of the insulin receptor nor of IRS1, but it enhanced the tyrosine phosphorylation of the p85 subunit of PI3K. The expression of the SHP-1/PTPN6 phosphatase, which dephosphorylates p85, was reduced after Reptin depletion. Forced expression of SHP-1 restored a normal AKT phosphorylation after insulin treatment in cells where Reptin was silenced, demonstrating that the downregulation of SHP1 is mechanistically linked to increased Akt phosphorylation. In conclusion, we have uncovered a new function for Reptin in regulating insulin signalling in HCC cells via the regulation of SHP-1 expression. We suggest that the regulation of insulin sensitivity by Reptin contributes to its oncogenic action in the liver.

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Liver haploinsufficiency of RuvBL1 causes hepatic insulin resistance and enhances hepatocellular carcinoma progression

Mello

Materozzi

Zanieri

et al. 2019

Intl Journal of Cancer

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RuvBL1 is an AAA+ ATPase whose expression in hepatocellular carcinoma (HCC) correlates with a poor prognosis. In vitro models suggest that targeting RuvBL1 could be an effective strategy against HCC. However, the role of RuvBL1 in the onset and progression of HCC remains unknown. To address this question, we developed a RuvBL1 hep+/− mouse model and evaluated the outcome of DEN-induced liver carcinogenesis up to 12 months of progression. We found that RuvBL1 haploinsufficiency initially delayed the onset of liver cancer, due to a reduced hepatocyte turnover in RuvBL1 hep+/− mice. However, RuvBL1 hep+/− mice eventually developed HCC nodules that, with aging, grew larger than in the control mice. Moreover, RuvBL1 hep+/− mice developed hepatic insulin resistance and impaired glucose homeostasis. We could determine that RuvBL1 regulates insulin signaling through the Akt/mTOR pathway in liver physiology in vivo as well as in normal hepatocytic and HCC cells in vitro. Whole transcriptome analysis of mice livers confirmed the major role of RuvBL1 in the regulation of hepatic glucose metabolism. Finally, RuvBL1 expression was found significantly correlated to glucose metabolism and mTOR signaling by bioinformatic analysis of human HCC sample from the publicly available TGCA database. These data uncover a role of RuvBL1 at the intersection of liver metabolism, hepatocyte proliferation and HCC development, providing a molecular rationale for its overexpression in liver cancer.M.M. and F.Z. contributed equally to this work Additional Supporting Information may be found in the online version of this article.

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Adenosine triphosphatase pontin is overexpressed in hepatocellular carcinoma and coregulated with reptin through a new posttranslational mechanism†

Cited by 57 publications

References 36 publications

The ATPase Activity of Reptin Is Required for Its Effects on Tumor Cell Growth and Viability in Hepatocellular Carcinoma

The ATPase Activity of Reptin Is Required for Its Effects on Tumor Cell Growth and Viability in Hepatocellular Carcinoma

Reptin regulates insulin‐stimulated Akt phosphorylation in hepatocellular carcinoma via the regulation of SHP‐1/PTPN6

Liver haploinsufficiency of RuvBL1 causes hepatic insulin resistance and enhances hepatocellular carcinoma progression

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