====== AMPK ======

5' AMP-activated [[protein kinase]] or AMPK or 5' adenosine monophosphate-activated protein kinase is an enzyme (EC 2.7.11.31) that plays a role in cellular energy homeostasis. It consists of three proteins (subunits) that together make a functional enzyme, conserved from yeast to humans. It is expressed in a number of tissues, including the liver, brain, and skeletal muscle. The net effect of AMPK activation is stimulation of hepatic fatty acid oxidation, ketogenesis, stimulation of skeletal [[muscle fatty]] acid oxidation and glucose uptake, inhibition of cholesterol synthesis, lipogenesis, and triglyceride synthesis, inhibition of adipocyte lipolysis and lipogenesis, and modulation of insulin secretion by pancreatic beta-cells.

It should not be confused with cyclic AMP-activated protein kinase (protein kinase A).
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[[AMP]]-activated protein kinase (AMPK) is a metabolic regulator that acts to limit the growth of [[cancer cell]]s. AMPK is downregulated by [[melanoma associated antigen]] A3/6 ([[MAGEA3]]/6), which are cancer-specific proteins that enhance the activity of specific E3 ubiquitin ligases to ubiquitinate and degrade AMP-activated protein kinase α1 (AMPKα1). Here, using a bioinformatic approach, we identified a microRNA, miR-1273 g-3p, that is predicted to target the 3' untranslated region (UTR) of MAGEA3/6. Analyzing miR-1273 g-3p expression in human colon cancer tissues, we found a reduction in miR-1273 g-3p expression correlating with increased MAGEA3/6 expression and AMPKα1 downregulation. Expression of miR-1273 g in HT-29 cells and primary human colon cancer cells down-regulated MAGEA3/6, leading to AMPKα1 upregulation, inhibition of proliferation and cell apoptosis. The anti-CRC activity of miR-1273 g was blocked by AMPKα1 knockout. MAGEA3/6 shRNA silencing mimicked and abolished miR-1273 g-induced actions in HT-29 cells. In vivo, miR-1273 g- or MAGEA3/6 shRNA-expressing HT-29 tumors grew significantly slower than control tumors. We propose a novel MicroRNA-based mechanism, whereby miR-1273 g represses MAGEA3/6 expression in human CRC cells and tissues, which may provide a novel cancer-specific therapeutic
((Wu F, Liu F, Dong L, Yang H, He X, Li L, Zhao L, Jin S, Li G. miR-1273g
silences MAGEA3/6 to inhibit human colorectal cancer cell growth via activation
of AMPK signaling. Cancer Lett. 2018 Jul 26. pii: S0304-3835(18)30495-6. doi:
10.1016/j.canlet.2018.07.031. [Epub ahead of print] PubMed PMID: 30056111.
)).