title: PP1γ functionally augments the alternative splicing of CaMKIIδ through interaction with ASF.
abstract: Protein phosphatase 1 (PP1) and Ca2+/calmodulin-dependent protein kinase δ (CaMKIIδ) are upregulated in heart disorders. Alternative splicing factor (ASF), a major splice factor for CaMKIIδ splicing, can be regulated by both protein kinase and phosphatase. Here we determine the role of PP1 isoforms in ASF-mediated splicing of CaMKIIδ in cells. We found that 1) PP1γ, but not α or β isoform, enhanced the splicing of CaMKIIδ in HEK293T cells; 2) PP1γ promoted the function of ASF, evidenced by the existence of ASF-PP1γ association as well as the PP1γ overexpression- or silencing-mediated change in CaMKIIδ splicing in ASF-transfected HEK293T cells; 3) CaMKIIδ splicing was promoted by overexpression of PP1γ and impaired by application of PP1 inhibitor 1 (I1PP1) or pharmacological inhibitor tautomycetin in primary cardiomyocytes; 4) CaMKIIδ splicing and enhancement of ASF-PP1γ association induced by oxygen-glucose deprivation followed by reperfusion (OGD/R) were potentiated by overexpression of PP1γ and suppressed by inhibition of PP1γ with I1PP1 or tautomycetin in primary cardiomyocytes; 5) functionally, overexpression and inhibition of PP1γ, 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 PP1γ 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 PP1γ-treated cells. In conclusion, our results show that PP1γ promotes the alternative splicing of CaMKIIδ through its interacting with ASF, exacerbating OGD/R-triggered apoptosis in primary cardiomyocytes.
authors.affiliation: Department of Pharmacology, School of Medicine, Nantong University, Nantong, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Huang
authors.forename: Wenwen
authors.initials: W
authors.lastname: Cao
authors.forename: Rujia
authors.initials: R
authors.lastname: Liao
authors.forename: Jia
authors.initials: J
authors.lastname: Wang
authors.forename: Yuzhe
authors.initials: Y
authors.lastname: Wang
authors.forename: Lijuan
authors.initials: L
authors.lastname: Tong
authors.forename: Xiangfan
authors.initials: X
authors.lastname: Chen
authors.forename: Weizhong
authors.initials: W
authors.lastname: Zhu
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
mesh_terms: D017398:Alternative Splicing / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000502:physiology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D057809:HEK293 Cells; D006801:Humans; D032383:Myocytes, Cardiac / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D054645:Protein Phosphatase 1 / Q000502:physiology*; D022821:RNA Splice Sites / Q000502:physiology*; D051381:Rats
chemical_list: D022821:RNA Splice Sites; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D054645:Protein Phosphatase 1
keywords: CaMKIIδC; alternative splicing factor; cardiomyocytes; protein phosphatase 1γ; splicing