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Skeletal Muscle miR-34a/SIRT1:AMPK Axis Is Activated in Experimental and Human Non-Alcoholic Steatohepatitis

Skeletal Muscle miR-34a/SIRT1:AMPK Axis Is Activated in Experimental and Human Non-Alcoholic Steatohepatitis

André L Simão, Marta B Afonso, Pedro M Rodrigues, Margarida Gama-Carvalho, Mariana V Machado, Helena Cortez-Pinto, Cecília M P Rodrigues, Rui E Castro

J Mol Med (Berl). 2019 Aug;97(8):1113-1126.

PMID: 31139863

Abstract:

Non-alcoholic fatty liver disease (NAFLD) pathogenesis associates with intramyocellular lipid deposition and mitochondrial dysfunction. microRNAs (miRs), including pro-apoptotic miR-34a, are modulated during disease progression in liver tissue and plasma. We aimed to investigate the functional role of the miR-34a/SIRT1:AMP-activated protein kinase (AMPK) pathway in modulating local mitochondrial dysfunction in the skeletal muscle of human and experimental non-alcoholic steatohepatitis. Muscle biopsies were obtained from morbid obese NAFLD patients undergoing bariatric surgery. C57BL/6N mice were fed different NAFLD-inducing diets and C2C12 muscle cells incubated with palmitic acid (PA) in the presence or absence of an AMPK activator, or upon miR-34a functional modulation. Several muscle miRNAs, including miR-34a, were found increased with human NAFLD progression. Activation of the miR-34a/SIRT1:AMPK pathway, concomitant with impairment in insulin signalling mediators and deregulation of mitochondrial-shaping proteins, was evident in C2C12 cells incubated with PA, as well as in the skeletal muscle of all three diet-induced NAFLD mice models. Functional studies established the association between miR-34a- and PA-induced muscle cell deregulation. Of note, activation of AMPK almost completely prevented miR-34a- and PA-induced cellular stress. In addition, the miR-34a/SIRT1:AMPK pathway and mitochondrial dynamics dysfunction were also found amplified in muscle of human NAFLD. Finally, muscle miR-34a expression and mitofusin 2 (Mfn2) protein levels correlated with hallmarks of NAFLD and disease progression. Our results indicate that activation of the miR-34a/SIRT1:AMPK pathway leads to mitochondrial dynamics dysfunction in skeletal muscle of human and experimental NAFLD, representing an appealing prospective target in metabolic syndrome. KEY MESSAGES: Skeletal muscle microRNAs are modulated during NAFLD progression. Palmitic acid-induced muscle cell dysfunction occurs, at least in part, through activation of the miR-34a/SIRT1:AMPK pathway. miR-34a/SIRT1:AMPK activation associates with mitochondria dynamics dysfunction in human NAFLD.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
IAR4246367	SIRT1 human			Price

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