Calmodulin-dependent Protein Kinase II Potentiates Transcriptional Activation through Activating Transcription Factor 1 but Not cAMP Response Element-binding Protein

Abstract

Activating transcription factor 1 (ATF1) and the cAMP response element-binding protein (CREB) are members of the CREB/ATF family implicated in cAMP- and calcium-induced transcriptional activation. Although ATF1 and CREB share extensive homology, the function of ATF1 is poorly understood. Its phosphorylation state and activation by Ca2+- and calmodulin-dependent protein kinase (CaMK) II were therefore examined. Phosphopeptide mapping analysis and Western blotting studies demonstrated that in vitro, CaMK II phosphorylates only Ser63 (corresponding to Ser133 of CREB), which is essential for the activation, and not Ser72 (corresponding to Ser142 of CREB), which is a negative regulation site. Both ATF1 and CREB bound CBP in a phosphorylation-dependent manner. As expected from these in vitro studies, transient transfection studies revealed that ATF1 is activated by CaMK II. Our findings suggest that CaMK II mediates transactivation of cAMP responsive genes via ATF1.

Phosphorylation of the cAMP Response Element-binding Protein and Activation of Transcription by α1 Adrenergic Receptors

“…There is recent evidence that CaMK II activates CRE-dependent transcription using ATF1 rather than CREB (35). In our studies, chelation of intracellular Ca 2ϩ significantly inhibited ␣ 1 adrenergic receptor-induced c-fos mRNA expression.…”

Essential role of calcium in the regulation of MAP kinase phosphatase-1 expression

“…Elevation of intracellular Ca 2+ levels has been shown to activate transcription of a number of eukaryotic genes through phosphorylation of transcription factors that bind to the CRE (cAMPresponsive element) (Sheng et al, 1990;Dash et al, 1991;Liu et al, 1993). This e ect of Ca 2+ may be mediated by the multifunctional Ca 2+ /calmodulindependent protein kinases (Schulman, 1993) which can phosphorylate and activate di erent members of the CRE-binding protein (CREB)/activating transcription factor (ATF) family, such as CREB, CREMt and ATF-1 (Dash et al, 1991;Sheng et al, 1991;Shimomura et al, 1996;de Groot et al, 1993;Sun et al, 1994c). In T lymphocytes, the activation of nuclear factor of activated T cells (NF-AT) is quantitatively correlated with the intracellular concentration of Ca 2+ (Negulescu et al, 1994).…”

EWS-ATF-1 chimeric protein in soft tissue clear cell sarcoma associates with CREB-binding protein and interferes with p53-mediated trans-activation function

“…The interaction between CBP and CREB is dependent on the phosphorylation status of Ser 133 in the KID domain, which represents a protein kinase A phosphoacceptor site (Chrivia et al, 1993;Arias et al, 1994). Similarly, when phosphorylated at Ser 63 (corresponding to Ser 133 of CREB), ATF-1 can bind to CBP and show augmented transcriptional activation to certain target promoters (Shimomura et al, 1996). In EWS-ATF-1, the N-terminal region of KID domain including the PKA phosphoacceptor site at Ser 63 was replaced by the N-terminal region of EWS gene (Figure 1), resulting in the loss of the phosphoacceptor site.…”