Anti-SIK1 monoclonal antibody

Distinct forms of MEF2 transcription factor act as positive or negative regulators of dendritic spine formation, with MEF2C playing a key regulator role in synapse plasticity. We report here that acute cocaine treatment of rats induced the expression of MEF2C in the striatum through a recently discovered transduction pathway. Repeated injections were found to induce MEF2C to a lesser extent. The mechanism by which MEF2C was induced involves the subsequent activation of the salt-inducible kinase SIK1 and the phosphorylation of HDAC5, a member of the class IIa of HDACs. Cocaine activated SIK1 by phosphorylation on Thr-182 residue, which was accompanied by the nuclear import of the kinase. In the nuclear compartment, SIK1 then phosphorylated HDAC5 causing the shuttling of its phospho-form from the nucleus to the cytoplasm of striatal cells. Activation of SIK1 by cocaine was further validated by the phosphorylation of TORC1/3, which was followed by the shuttling of TORC proteins from the nucleus to the cytoplasm. Activation of MEF2C was assessed by measuring the expression of the MEF2C gene itself, since the gene is known to be under the control of its own product. Since MEF2C plays a key role in memory/learning processes, activation of this pathway by cocaine is probably involved in plasticity mechanisms whereby the drug establishes its long-term effects such as drug dependence. Synapse 66:61-70, 2012. (C) 2011 Wiley Periodicals, Inc.

Salt-inducible kinases (SIKs) represent a subfamily of AMP-activated protein kinase (AMPK) family kinases. Initially named because SIK1 (the founding member of this kinase family) expression is regulated by dietary salt intake in the adrenal gland, it is now apparent that a major biological role of these kinases is to control gene expression in response to extracellular cues that increase intracellular levels of cAMP. Here, we review four physiologically relevant examples of how cAMP signaling impinges upon SIK cellular function. By focusing on examples of cAMP-mediated SIK regulation in gut myeloid cells, bone, liver, and skin, we highlight recent advances in G protein-coupled receptor (GPCR) signal transduction. New knowledge regarding the role of SIKs in GPCR signaling has led to therapeutic applications of novel small molecule SIK inhibitors.