ABSTRACT
Aim: To explore whether RIP140 and TNF-a regulate energy metabolism in cardiomyocytes. Methods: H9c2 cardiomyocytes were infected with Ad-RIP140, simultaneously with or without TNF-α treatment. The mRNA levels of PPAR-α, PPAR-β/δ, and PDK4 were measured. H9c2 was exposed to adenovirus expressing RIP140-specific or nonspecific control. Expression of p65 in the nucleus and IκB-α: in cytoplasm were measured by Western blotting, and mRNA levels of IL-1β, IL-2 and TNF-α were measured by real-time PCR. H9c2 was treated with or without TNF-α. The mRNA and protein levels of RIP140 were measured. Results: Overexpression of RIP140 led to a decrease in mRNA levels of PPAR-α, PPAR-β/δ, PDK4, while TNF-α aggravated down-regulation of key metabolic genes by superabundant RIP140. A marked increase of p65-NF-κB in nuclear, a significant decrease of IκB-α in cytoplasm and a notable increase in mRNA levels of TNF-α, IL-β and IL-2 in H9c2 cell line were observed following overexpression of RIP140. The mRNA and protein levels of RIP140 were up-regulated by TNF-α treatment. Conclusions: RIP140 and TNF-a may collaborate in mediating proinflammatory processes and metabolic dysregulation in cardiomyocytes.
ABSTRACT
[Objective]To investigate the effect of desuccinylase Sirtuin5 (SIRT5) on receptor-interacting protein 140 (RIP140)- mediated metabolic dysfunction in cardiomyocytes.[Methods]RIP140 was overexpressed by Adenovirus infection and SIRT5 was overexpressed by plasmid transfection. RIP140 and SIRT5 were knocked down by siRNA interference. The expression of RIP140 and SIRT5 were measured by qRT-PCR and western blot. The transcription levels of mitochondrial DNA-encoded genes were detected by qRT-PCR. Mitochondrial membrane potential was detected by tetramethylrhodamine ethyl ester(TMRE)fluorescence anl?ysis. Cellular oxygen consumption and ATP production were investigated by assay kits. All data are from at least three independent ex?periments.[Results]RIP140 overexpression significantly attenuated SIRT5 expression(P<0.05),whereas knockdown of endogenous RIP140 elevated SIRT5 expression(P<0.05)in cardiomyocytes. Superabundant RIP140 also induced hypersuccinylation of mitochon?drial proteins,suggesting RIP140 could repress the desuccinylase activity of SIRT5. Moreover,SIRT5 overexpression reversed RIP140-mediated mitochondrial dysfunction and energy metabolic impairment ,such as repression of mitochondrial DNA-encoded genes(P<0.05),decrease of mitochondrial membrane potential(P<0.05),as well as reduction of cellular oxygen consumption(P<0.05)and ATP production(P<0.05). Furthermore,the regulation of RIP140 on SIRT5 was dependent on the peroxisome proliferator-activated receptorα(PPARα)in cardiomyocytes.[Conclusion]RIP140 induces mitochondrial dysfunction and metabolic impairment through repression of SIRT5 in cardiomyocytes.
ABSTRACT
Nuclear receptors(NRs)superfamily signaling plays an important role in regulating the expression of gene involved inenergy homeostasis.The nuclear receptors regulate target gene expression through the recruitment of coregulatory proteins,which act as scaffolds or plateforms for linking NRs with enzyme complexes that modify DNA and histones.As a transcriptional co-repressor for NRs,RIP140 negatively regulates the transcription of target gene in metabolic tissue,such as adipose tissue,muscle and liver.In the absence of RIP140,genes expressions involved in metabolic pathways were upregulated including glycolysis,triglyceride synthesis,TCA cycle,fatty acid ? oxidation,mitochondrial electron transport and oxidative phosphorylation.RIP140 may be a candidate therapeutic target for metabolism syndromes.