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J. Biol. Chem., Vol. 283, Issue 27, 99931, July 4, 2008

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Another Role for AMP-activated Protein Kinase

AMP-activated protein kinase was first identified as a cellular energy sensor, but recently its role has been expanding into other biological processes. As Sandrine Horman and colleagues discuss in this Paper of the Week, smooth muscle contraction may now have to be added to this growing list. The researchers provide a broad set of evidence that AMP-activated protein kinase (AMPK) phosphorylates myosin light chain kinase (MLCK) in the calmodulin binding domain (Ser⁸¹⁵); phosphorylation desensitizes MLCK to calcium-triggered calmodulin activation and reduces its ability to trigger myosin cross-bridge formation and subsequent contraction. In primary smooth cell cultures, the addition of vasoconstrictors could activate AMPK in a calcium-dependent manner, and likewise mice with the smooth muscle isoform of AMPK deleted experienced stronger contractions in the aortic ring. This study defines a potentially new signaling pathway controlling smooth muscle activity, in which AMPK attenuates contractions by phosphorylating MLCK. Horman and colleagues suggest this attenuation might contribute to reduced ATP turnover in the tonic phase of smooth muscle contraction.

The aortic rings of 1-AMPK knock-out mice (open box) display stronger contractions than wild-type animals (black box) when stimulated by phenylephrine.

FOOTNOTES

See referenced article, J. Biol. Chem. 2008, 283, 18505-18512

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This Article Full Text (PDF) Author Profile Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Related Collections Papers Of The Week Social Bookmarking                      What's this?