Crosstalk between AMPK activation and angiotensin II-induced hypertrophy in cardiomyocytes: the role of mitochondria.
AMP-kinase (AMPK) activation reduces cardiac hypertrophy, although underlying molecular mechanisms remain unclear. In this study, we elucidated the anti-hypertrophic action of metformin, specifically, the role of the AMPK/eNOS/p53 pathway. H9c2 rat cardiomyocytes were treated with angiotensin II (AngII) for 24 hrs in the presence or absence of metformin (AMPK agonist), losartan [AngII type 1 receptor (AT1R) blocker], Nω-nitro-L-arginine methyl ester (L-NAME, pan-NOS inhibitor), splitomicin (SIRT1 inhibitor) or pifithrin-α (p53 inhibitor). Results showed that treatment with metformin significantly attenuated AngII-induced cell hypertrophy and death. Metformin attenuated AngII-induced activation (cleavage) of caspase 3, Bcl-2 down-regulation and p53 up-regulation. It also reduced AngII-induced AT1R up-regulation by 30% (P < 0.05) and enhanced AMPK phosphorylation by 99% (P < 0.01) and P-eNOS levels by 3.3-fold (P < 0.01). Likewise, losartan reduced AT1R up-regulation and enhanced AMPK phosphorylation by 54% (P < 0.05). The AMPK inhibitor, compound C, prevented AT1R down-regulation, indicating that metformin mediated its effects via AMPK activation. Beneficial effects of metformin and losartan converged on mitochondria that demonstrated high membrane potential (Δψm ) and low permeability transition pore opening. Thus, this study demonstrates that the anti-hypertrophic effects of metformin are associated with AMPK-induced AT1R down-regulation and prevention of mitochondrial dysfunction through the SIRT1/eNOS/p53 pathway.
Department of Physiology, School of Medicine, University of Puerto Rico, San Juan, PR, USA.
Jessica Soto
JS
Hernández
Giselle
G
Barreto-Torres
Andrey V
AV
Kuznetsov
Zaza
Z
Khuchua
Sabzali
S
Javadov
D055372:AMP-Activated Protein Kinases / Q000096:biosynthesis / Q000378:metabolism*; D000804:Angiotensin II / Q000008:administration & dosage*; D047228:Angiotensin II Type 1 Receptor Blockers / Q000008:administration & dosage; D000818:Animals; D006332:Cardiomegaly / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D005786:Gene Expression Regulation / Q000187:drug effects; D019808:Losartan / Q000008:administration & dosage; D008687:Metformin / Q000008:administration & dosage; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D051381:Rats; D044140:Receptor, Angiotensin, Type 1 / Q000096:biosynthesis; D015398:Signal Transduction; D056564:Sirtuin 1 / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D047228:Angiotensin II Type 1 Receptor Blockers; D044140:Receptor, Angiotensin, Type 1; D016159:Tumor Suppressor Protein p53; D000804:Angiotensin II; D008687:Metformin; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D055372:AMP-Activated Protein Kinases; C488368:Sirt1 protein, rat; D056564:Sirtuin 1; D019808:Losartan
AMP kinase; angiotensin II receptors; hypertrophy; metformin; mitochondria