PP1γ functionally augments the alternative splicing of CaMKIIδ through interaction with ASF

Abstract

W. PP1␥ functionally augments the alternative splicing of CaMKII␦ through interaction with ASF. Am J Physiol Cell Physiol 306: C167-C177, 2014. First published November 6, 2013 doi:10.1152/ajpcell.00145.2013.-Protein phosphatase 1 (PP1) and Ca 2ϩ /calmodulin-dependent protein kinase ␦ (CaMKII␦) are upregulated in heart disorders. Alternative splicing factor (ASF), a major splice factor for CaMKII␦ splicing, can be regulated by both protein kinase and phosphatase. Here we determine the role of PP1 isoforms in ASF-mediated splicing of CaMKII␦ in cells. We found that 1) PP1␥, but not ␣ or ␤ isoform, enhanced the splicing of CaMKII␦ in HEK293T cells; 2) PP1␥ promoted the function of ASF, evidenced by the existence of ASF-PP1␥ association as well as the PP1␥ overexpression-or silencing-mediated change in CaMKII␦ splicing in ASFtransfected HEK293T cells; 3) CaMKII␦ splicing was promoted by overexpression of PP1␥ and impaired by application of PP1 inhibitor 1 (I1PP1) or pharmacological inhibitor tautomycetin in primary cardiomyocytes; 4) CaMKII␦ splicing and enhancement of ASF-PP1␥ association induced by oxygen-glucose deprivation followed by reperfusion (OGD/R) were potentiated by overexpression of PP1␥ and suppressed by inhibition of PP1␥ with I1PP1 or tautomycetin in primary cardiomyocytes; 5) functionally, overexpression and inhibition of PP1␥, respectively, potentiated or suppressed the apoptosis and Bax/Bcl-2 ratio, which were associated with the enhanced activity of CaMKII in OGD/R-stimulated cardiomyocytes; and 6) CaMKII was required for the OGD/R induced-and PP1␥ exacerbated-apoptosis of cardiomyocytes, evidenced by a specific inhibitor of CaMKII KN93, but not its structural analog KN92, attenuating the apoptosis and Bax/Bcl-2 ratio in OGD/R and PP1␥-treated cells. In conclusion, our results show that PP1␥ promotes the alternative splicing of CaMKII␦ through its interacting with ASF, exacerbating OGD/R-triggered apoptosis in primary cardiomyocytes.protein phosphatase 1␥; alternative splicing factor; CaMKII␦C; splicing; cardiomyocytes

The microRNA cluster miR-183/96/182 contributes to long-term memory in a protein phosphatase 1-dependent manner

“…It could also act on splicing since it can interact with components of the spliceosome machinery, known to crosstalk with nuclear miRNA processing43444546. Binding of proteins such as Tra2β1, SF2A, Srp30c and ASF to PP1 through conserved RNA recognizing domains is essential for correct splice site selection4247, and by extension may also affect miRNA processing. Interestingly, a recent study demonstrated a developmentally timed processing of pri-miR-183/96/182 involved in neuronal organization.…”

CaMKIIδ and cardiomyocyte Ca2+ signalling new perspectives on splice variant targeting

“…In cardiomyocytes subjected to ischemia/reperfusion or H 2 O 2 treatment, CaMKII δ C increased and CaMKII δ B decreased rapidly to a new steady‐state within 8 hours of treatment onset . Indeed, regulation of relative CaMKII δ C / δ B expression ratio is likely regulated by numerous factors within the myocyte, including kinase/phosphatase activity and oxygen/glucose availability . Together these findings have provided support for the notion that intra/extracellular environmental factors regulate both the relative expression and activity of the CaMKII δ C / δ B variants and their net influence on cardiomyocyte responses, thereby determining overall cardiomyocyte vulnerability to CaMKII δ ‐driven functional and structural outcomes (i.e.…”

CaMKIIdelta subtypes: localization and function

“…Protein kinase A (PKA)-mediated ASF/SF2 phosphorylation has been correlated with alternative splicing of CaMKIIδ in heart and brain (Gu et al, 2011). Additionally, regulation of ASF/SF2 by Protein phosphatase 1 γ (PP1γ) has been demonstrated to affect CaMKIIδ splicing (Huang et al, 2013). CaMKIIδ A expression is increased in models of isoproterenol-induced cardiac hypertrophy and thus regulation of CaMKIIδ splicing by PKA and PP1γ may be relevant in the context of chronic β-adrenergic stimulation (Li et al, 2011).…”