Unbiased identification of novel AMPK substrates by chemical genetics

Abstract

The energy‐sensing AMP‐activated protein kinase (AMPK) is activated by low nutrient levels. We showed that AMPK mediates lifespan extension by some dietary restriction regimens in C. elegans. Functions of AMPK other than its role in cellular metabolism are beginning to emerge. To identify novel AMPK substrates in mammalian cells, we used an unbiased chemical genetic screen. We created an analog‐specific version of AMPK that uses a bulky analog of ATP and transfers the phosphate group to specific substrates in cells. Coupled with mass spectrometry, this approach allowed us to identify 30 novel AMPK substrates. Our results indicate that AMPK phosphorylates components of the mitotic apparatus, providing an intriguing link between energy sensing and the completion of mitosis. Our findings indicate that AMPK coordinates nutrient status with mitosis completion, which may be critical for the organism's response to low nutrients during development, or in adult stem and cancer cells. These studies may also help uncover mechanisms by which dietary restriction extends lifespan.