Cloning of a novel kinase (SIK) of the SNF1/AMPK family from high salt diet-treated rat adrenal

PCR-coupled cDNA subtraction hybridization was adapted to identify the genes expressed in the adrenocortical tissues from high salt diet-treated rat. A novel cDNA done, termed salt-inducible kinase (SIK), encoding a polypeptide (776 amino acids) with significant similarity to protein serine/threonine kinases in the SNF1/AMPK family was isolated. An in vitro kinase assay demonstrated that SIK protein had autophosphorylation activity. Northern blot revealed that SIK mRNA levels were markedly augmented by ACTH treatment both in rat adrenal glands and in Y1 cells. SIK may play an important role in the regulation of adrenocortical functions in response to high plasma salt and ACTH stimulation.