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The AMPK-related kinase SIK2 is regulated by cAMP via phosphorylation at Ser(358) in adipocytes

Henriksson, Emma LU ; Jones, Helena LU ; Patel, Kashyap; Peggie, Mark; Morrice, Nicholas; Sakamoto, Kei and Göransson, Olga LU (2012) In Biochemical Journal 444. p.503-514
Abstract
SIK2 (salt-inducible kinase 2) is a member of the AMPK (AMP-activated protein kinase) family of kinases and is highly expressed in adipocytes. We investigated the regulation of SIK2 in adipocytes in response to cellular stimuli with relevance for adipocyte function and/or AMPK signalling. None of the treatments, including insulin, cAMP inducers or AICAR (5-amino-4-imidazolecarboxamide riboside), affected SIK2 activity towards peptide or protein substrates in vitro. However, stimulation with the cAMP-elevating agent forskolin and the beta-adrenergic receptor agonist CL 316,243 resulted in a PKA (protein kinase A)-dependent phosphorylation and 14-3-3 binding of SIK2. Phosphopeptide mapping of SIK2 revealed several sites phosphorylated in... (More)
SIK2 (salt-inducible kinase 2) is a member of the AMPK (AMP-activated protein kinase) family of kinases and is highly expressed in adipocytes. We investigated the regulation of SIK2 in adipocytes in response to cellular stimuli with relevance for adipocyte function and/or AMPK signalling. None of the treatments, including insulin, cAMP inducers or AICAR (5-amino-4-imidazolecarboxamide riboside), affected SIK2 activity towards peptide or protein substrates in vitro. However, stimulation with the cAMP-elevating agent forskolin and the beta-adrenergic receptor agonist CL 316,243 resulted in a PKA (protein kinase A)-dependent phosphorylation and 14-3-3 binding of SIK2. Phosphopeptide mapping of SIK2 revealed several sites phosphorylated in response to cAMP induction, including Ser(358). Site-directed mutagenesis demonstrated that phosphorylation of See(358), but not the previously reported PKA site See(587), was required for 14-3-3 binding. Immunocytochemistry illustrated that the localization of exogenously expressed SIK2 in HEK (human embryonic kidney)-293 cells was exclusively cytosolic and remained unchanged after cAMP elevation. Fractionation of adipocytes, however, revealed a significant increase of wild-type, but not Ser358Ala, HA (haemagglutinin) SIK2 in the cytosol and a concomitant decrease in a particulate fraction after CL 316,243 treatment. This supports a phosphorylation-dependent relocalization in adipocytes. We hypothesize that regulation of SIK2 by cAMP could play a role for the critical effects of this second messenger on lipid metabolism in adipocytes. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
14-3-3, cAMP, insulin, phosphorylation, salt-induced kinase (SIK), 3T3-L1 adipocyte
in
Biochemical Journal
volume
444
pages
503 - 514
publisher
Portland Press Limited
external identifiers
  • wos:000305545300015
  • scopus:84862237698
ISSN
0264-6021
DOI
10.1042/BJ20111932
language
English
LU publication?
yes
id
850506ad-f857-4351-8616-907aa7f44c60 (old id 2887455)
date added to LUP
2012-08-01 09:40:55
date last changed
2017-10-29 03:57:36
@article{850506ad-f857-4351-8616-907aa7f44c60,
  abstract     = {SIK2 (salt-inducible kinase 2) is a member of the AMPK (AMP-activated protein kinase) family of kinases and is highly expressed in adipocytes. We investigated the regulation of SIK2 in adipocytes in response to cellular stimuli with relevance for adipocyte function and/or AMPK signalling. None of the treatments, including insulin, cAMP inducers or AICAR (5-amino-4-imidazolecarboxamide riboside), affected SIK2 activity towards peptide or protein substrates in vitro. However, stimulation with the cAMP-elevating agent forskolin and the beta-adrenergic receptor agonist CL 316,243 resulted in a PKA (protein kinase A)-dependent phosphorylation and 14-3-3 binding of SIK2. Phosphopeptide mapping of SIK2 revealed several sites phosphorylated in response to cAMP induction, including Ser(358). Site-directed mutagenesis demonstrated that phosphorylation of See(358), but not the previously reported PKA site See(587), was required for 14-3-3 binding. Immunocytochemistry illustrated that the localization of exogenously expressed SIK2 in HEK (human embryonic kidney)-293 cells was exclusively cytosolic and remained unchanged after cAMP elevation. Fractionation of adipocytes, however, revealed a significant increase of wild-type, but not Ser358Ala, HA (haemagglutinin) SIK2 in the cytosol and a concomitant decrease in a particulate fraction after CL 316,243 treatment. This supports a phosphorylation-dependent relocalization in adipocytes. We hypothesize that regulation of SIK2 by cAMP could play a role for the critical effects of this second messenger on lipid metabolism in adipocytes.},
  author       = {Henriksson, Emma and Jones, Helena and Patel, Kashyap and Peggie, Mark and Morrice, Nicholas and Sakamoto, Kei and Göransson, Olga},
  issn         = {0264-6021},
  keyword      = {14-3-3,cAMP,insulin,phosphorylation,salt-induced kinase (SIK),3T3-L1 adipocyte},
  language     = {eng},
  pages        = {503--514},
  publisher    = {Portland Press Limited},
  series       = {Biochemical Journal},
  title        = {The AMPK-related kinase SIK2 is regulated by cAMP via phosphorylation at Ser(358) in adipocytes},
  url          = {http://dx.doi.org/10.1042/BJ20111932},
  volume       = {444},
  year         = {2012},
}