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  • Title: 5-Aminoimidazole-4-carboxyamide-1-β-D-ribofranoside stimulates the rat enhancer of split- and hairy-related protein-2 gene via atypical protein kinase C lambda.
    Author: Komatsu Y, Yanagisawa Y, Moriizumi M, Tsuchiya Y, Yokouchi H, Otsuka H, Aoyagi M, Tsukada A, Kanai Y, Haneishi A, Takagi K, Asano K, Ono M, Tanaka T, Tomita K, Yamada K.
    Journal: J Biochem; 2016 Apr; 159(4):429-36. PubMed ID: 26590300.
    Abstract:
    The 5'-AMP-activated protein kinase (AMPK) functions as a cellular energy sensor. 5-Aminoimidazole-4-carboxyamide-1-β-D-ribofranoside (AICAR) is a chemical activator of AMPK. In the liver, AICAR suppresses expression of thephosphoenolpyruvate carboxykinase(PEPCK) gene. The rat enhancer of split- and hairy-related protein-2 (SHARP-2) is an insulin-inducible transcriptional repressor and its target is thePEPCKgene. In this study, we examined an issue of whether theSHARP-2gene expression is regulated by AICAR via the AMPK. AICAR increased the level of SHARP-2 mRNA in H4IIE cells. Whereas an AMPK inhibitor, compound-C, had no effects on the AICAR-induction, inhibitors for both phosphoinositide 3-kinase (PI 3-K) and protein kinase C (PKC) completely diminished the effects of AICAR. Western blot analyses showed that AICAR rapidly activated atypical PKC lambda (aPKCλ). In addition, when a dominant negative form of aPKCλ was expressed, the induction of SHARP-2 mRNA level by AICAR was inhibited. Calcium ion is not required for the activation of aPKCλ. A calcium ion-chelating reagent had no effects on the AICAR-induction. Furthermore, the AICAR-induction was inhibited by treatment with an RNA polymerase inhibitor or a protein synthesis inhibitor. Thus, we conclude that the AICAR-induction of theSHARP-2gene is mediated at transcription level by a PI 3-K/aPKCλ pathway.
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