| Regulation of AMP-activated protein kinase by LKB1 and CaMKK in adipocytes. | |
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MedLine Citation:
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PMID: 21312243 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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AMP-activated protein kinase (AMPK) is a serine/threonine kinase that regulates cellular and whole body energy homeostasis. In adipose tissue, activation of AMPK has been demonstrated in response to a variety of extracellular stimuli. However, the upstream kinase that activates AMPK in adipocytes remains elusive. Previous studies have identified LKB1 as a major AMPK kinase in muscle, liver and other tissues. In certain cell types, Ca(2+) /Calmodulin-dependent protein kinase kinase (CaMKK) β has been shown to activate AMPK in response to increase of intracellular Ca(2+) levels. Our aim was to investigate if LKB1 and/or CaMKK function as AMPK kinases in adipocytes. We used adipose tissue and isolated adipocytes from mice in which the expression of LKB1 was reduced to 10-20% of that of wild-type (LKB1 hypomorphic mice). We show that adipocytes from LKB1 hypomorphic mice display a 40% decrease in basal AMPK activity and a decrease of AMPK activity in the presence of the AMPK activator phenformin. We also demonstrate that stimulation of 3T3L1 adipocytes with intracellular [Ca(2+) ]-raising agents results in an activation of the AMPK pathway. The inhibition of CaMKK isoforms, particularly CaMKKβ, by the inhibitor STO-609 or by siRNAs, blocked Ca(2+) -, but not phenformin-, AICAR or forskolin-induced activation of AMPK, indicating that CaMKK activated AMPK in response to Ca(2+) . Collectively, we show that LKB1 is required to maintain normal AMPK-signalling in non-stimulated adipocytes and in the presence of phenformin. In addition, we demonstrate the existence of a Ca(2+) /CaMKK signalling pathway that can also regulate the activity of AMPK in adipocytes. J. Cell. Biochem. © 2011 Wiley-Liss, Inc. |
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Authors:
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Amélie Gormand; Emma Henriksson; Kristoffer Ström; Thomas Elbenhardt Jensen; Kei Sakamoto; Olga Göransson |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-2-10 |
Journal Detail:
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Title: Journal of cellular biochemistry Volume: - ISSN: 1097-4644 ISO Abbreviation: - Publication Date: 2011 Feb |
Date Detail:
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Created Date: 2011-2-11 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8205768 Medline TA: J Cell Biochem Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Copyright Information:
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Copyright © 2011 Wiley-Liss, Inc. |
Affiliation:
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Protein Phosphorylation Research Group, Department of Experimental Medical Science, Lund University, BMC C11, SE 221 84 Lund, Sweden. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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