Pyruvate kinase M2 isoform regulates mitochondrial biogenesis and energy metabolism in cardiomyocytes
Objective To investigate the role of pyruvate kinase M2 isomer(PKM2)in mitochondrial biogenesis,mitochondrial dynam-ics and energy metabolism in cardiomyocytes under hypoxia.Methods The rats cardiomyocytes were stimulated with cobalt chloride(CoCl2)at different concentration gradients of H9C2 to simulate hypoxia environment in vivo.The expression levels of PKM2,mito-chondrial biogenesis and energy metabolism related molecules were detected by reverse transcription polymerase chain reaction and western blot.The cytoplasmic and cytonuclear proteins in H9C2 cardiomyocytes were isolated,and the location of PKM2 in H9C2 car-diomyocytes was detected by western blot,while the location of PKM2 in H9C2 cardiomyocytes was detected by immunofluorescence staining.Adenosine triphosphate(ATP)assay kit was used to detect the effect of PKM2 on ATP production in H9C2 cardiomyocytes un-der hypoxia.H9C2 cardiomyocytes were transfected with PKM2 plasmid and PKM2 siRNA and stimulated with CoCl2(300 μmol/L)for 24 hours.Western blot analysis was performed to determine the effects of PKM2 on mitochondrial biogenesis and mitochondrial fusion in H9C2 cardiomyocytes.Results The expression of PKM2 decreased gradually in hypoxic H9C2 cardiomyocytes,which was closely related to the expression of molecules related to mitochondrial biogenesis and function.PKM2 was mainly expressed in the cytoplasm of cardiomyocytes and colocates with the mitochondrial marker molecule heat shock protein 60(HSP60).PKM2 overexpression could pro-mote mitochondrial biogenesis,mitochondrial fusion and ATP production in hypoxic cardiomyocytes.Conversely,PKM2 knockdown in-hibited mitochondrial biogenesis,mitochondrial fusion and ATP production in hypoxic cardiomyocytes.Conclusion PKM2 is essential for mitochondrial biogenesis and dynamics in H9C2 cardiomyocytes under hypoxia conditions,thus controlling energy metabolism in H9C2 cardiomyocytes.
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