Isoform-specific roles of protein phosphatase 1 catalytic subunits in sarcoplasmic reticulum-mediated Ca2+ cycling

被引：49

作者：

Aoyama, Hidekazu ^{[1
]}

Ikeda, Yasuhiro ^{[1
,2
]}

Miyazaki, Yosuke ^{[1
]}

Yoshimura, Koichi ^{[2
]}

Nishino, Shizuka ^{[1
,2
]}

Yamamoto, Takeshi ^{[1
]}

Yano, Masafumi ^{[1
]}

Inui, Makoto ^{[3
]}

Aoki, Hiroki ^{[2
]}

Matsuzaki, Masunori ^{[1
,2
]}

机构：

[1] Yamaguchi Univ, Grad Sch Med, Dept Med & Clin Sci, Div Cardiol, Yamaguchi 7558505, Japan

[2] Yamaguchi Univ, Grad Sch Med, Dept Mol Cardiovasc Biol, Yamaguchi 7558505, Japan

[3] Yamaguchi Univ, Grad Sch Med, Dept Pharmacol, Yamaguchi 7558505, Japan

来源：

CARDIOVASCULAR RESEARCH | 2011年 / 89卷 / 01期

关键词：

Protein phosphatase 1; Calcium cycling; Sarcoplasmic reticulum; RNAi; Rat cardiomyocytes; HEART-FAILURE; CARDIAC-FUNCTION; MAMMALIAN-CELLS; GENE-TRANSFER; EXPRESSION; APOPTOSIS; THERAPY; MUSCLE;

D O I：

10.1093/cvr/cvq252

中图分类号：

R5 [内科学];

学科分类号：

1002 ; 100201 ;

摘要：

Aims Protein phosphatase 1 (PP1) is the major isotype of serine/threonine phosphatase in cardiomyocytes, and its activity has been thought to be important for heart failure progression. The PP1 catalytic subunits consist of three distinct genes, PP1 alpha, PP1 beta/delta, and PP1 gamma. To date, the function of each PP1 isoform is not well characterized in cardiomyocytes. We sought to determine the functional contribution of each PP1 isoform to sarcoplasmic reticulum (SR)-mediated Ca2+ cycling in isolated adult rat cardiomyocytes. Methods and results Adenoviral vectors encoding short hairpin RNA for each PP1 isoform were transfected into isolated rat cardiomyocytes, and this was followed by analysis of cell shortening, Ca2+ transients, and the phosphorylation levels of Ca2+ regulatory proteins. Physical interactions between each PP1 isoform and SR Ca2+ regulatory proteins were characterized in isolated cardiomyocytes expressing green fluorescent protein (GFP)-tagged PP1 catalytic subunits, and also in canine junctional and longitudinal SR preparations. Successful PP1 isoform knockdown was achieved for each isoform without affecting the expression of the other isoforms. PP1 beta knockdown most significantly enhanced the Ca2+ transient and cell shortening by augmenting phospholamban (PLN) phosphorylation at baseline and with low-dose isoproterenol stimulation (10 nM). Interestingly, PP1 beta was preferentially associated with sarco-endoplasmic ATPase and PLN in GFP-PP1-transfected cardiomyocytes, as well as in canine longitudinal SR preparations. Conclusion These findings indicate that PP1 beta is the most significant PP1 isoform involved in regulating SR Ca2+ cycling in rat cardiomyocytes.

引用

页码：79 / 88

页数：10

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