title: CPK12: A Ca2+-dependent protein kinase balancer in abscisic acid signaling.
abstract: Ca2+ is believed to be a critical second messenger in ABA signal transduction. Ca2+-dependent protein kinases (CDPKs) are the best characterized Ca2+ sensors in plants. Recently, we identified an Arabidopsis CDPK member CPK12 as a negative regulator of ABA signaling in seed germination and post-germination growth, which reveals that different members of the CDPK family may constitute a regulation loop by functioning positively and negatively in ABA signal transduction. We observed that both RNA interference and overexpression of CPK12 gene resulted in ABA-hypersensitive phenotypes in seed germination and post-germination growth, suggesting a high complexity of the CPK12-mediated ABA signaling pathway. CPK12 stimulates a negative ABA-signaling regulator (ABI2) and phosphorylates two positive ABA-signaling regulators (ABF1 and ABF4), which may partly explain the ABA hypersensitivity induced by both downregulation and upregulation of CPK12 expression. Our data indicate that CPK12 appears to function as a balancer in ABA signal transduction in Arabidopsis.
authors: School of Life Sciences, Tsinghua University, Beijing, China.
authors: Rui
authors: R
authors: Zhao
authors: Xiao-Fang
authors: XF
authors: Wang
authors: Da-Peng
authors: DP
authors: Zhang
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D018525:Germination; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D000040:Abscisic Acid; C568892:CPK12 protein, Arabidopsis; D017871:Calcium-Calmodulin-Dependent Protein Kinases