Dataset Information
Metformin activates AMP-activated protein kinase in primary human hepatocytes by decreasing cellular energy status.
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ABSTRACT: Aim/hypothesis
The glucose-lowering drug metformin has been shown to activate hepatic AMP-activated protein kinase (AMPK), a master kinase regulating cellular energy homeostasis. However, the underlying mechanisms remain controversial and have never been investigated in primary human hepatocytes.Methods
Hepatocytes isolated from rat, mouse and human livers were treated with various concentrations of metformin. Isoform-specific AMPK? abundance and activity, as well as intracellular adenine nucleotide levels and mitochondrial oxygen consumption rates were determined at different time points.Results
Metformin dose- and time-dependently increased AMPK activity in rat and human hepatocytes, an effect associated with a significant rise in cellular AMP:ATP ratio. Surprisingly, we found that AMPK?2 activity was undetectable in human compared with rat hepatocytes, while AMPK?1 activities were comparable. Accordingly, metformin only increased AMPK?1 activity in human hepatocytes, although both AMPK? isoforms were activated in rat hepatocytes. Analysis of mRNA expression and protein levels confirmed that only AMPK?1 is present in human hepatocytes; it also showed that the distribution of ? and ? regulatory subunits differed between species. Finally, we demonstrated that the increase in AMP:ATP ratio in hepatocytes from liver-specific Ampk?1/2 (also known as Prkaa1/2) knockout mice and humans is due to a similar and specific inhibition of the mitochondrial respiratory-chain complex 1 by metformin.Conclusions/interpretation
Activation of hepatic AMPK by metformin results from a decrease in cellular energy status owing to metformin's AMPK-independent inhibition of the mitochondrial respiratory-chain complex 1. The unique profile of AMPK subunits found in human hepatocytes should be considered when developing new pharmacological agents to target the kinase.
SUBMITTER: Stephenne X
PROVIDER: S-EPMC3210354 | biostudies-literature | 2011 Dec
REPOSITORIES: biostudies-literature
Publications
Metformin activates AMP-activated protein kinase in primary human hepatocytes by decreasing cellular energy status.
Diabetologia 20110923 12
<h4>Aim/hypothesis</h4>The glucose-lowering drug metformin has been shown to activate hepatic AMP-activated protein kinase (AMPK), a master kinase regulating cellular energy homeostasis. However, the underlying mechanisms remain controversial and have never been investigated in primary human hepatocytes.<h4>Methods</h4>Hepatocytes isolated from rat, mouse and human livers were treated with various concentrations of metformin. Isoform-specific AMPKα abundance and activity, as well as intracellula ...[more]