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Pik3ip1 modulates cardiac hypertrophy by inhibiting PI3K pathway.

ABSTRACT: Cardiac hypertrophy is an adaptive response to various physiological and pathological stimuli. Phosphoinositide-3 kinase (PI3K) is a highly conserved lipid kinase involved in physiological cardiac hypertrophy (PHH). PI3K interacting protein1 (Pik3ip1) shares homology with the p85 regulatory subunit of PI3K and is known to interact with the p110 catalytic subunit of PI3K, leading to attenuation of PI3K activity in liver and immune cells. However, the role of Pik3ip1 in the heart remains unknown. In the present study, the effects of Pik3ip1 on cardiac hypertrophy were examined. We found that the expression level of Pik3ip1 was markedly higher in cardiomyocytes than in fibroblasts. The interaction of Pik3ip1 with the p110a subunit of PI3K in the heart was identified by immunoprecipitation using neonatal rat cardiomyocytes (NRCM). Approximately 35% knockdown of Pik3ip1 was sufficient to induce myocardial hypertrophy. Pik3ip1 deficiency was shown to lead to activation of PI3K/protein kinase B (AKT)/ mammalian target of rapamycin (mTOR) signaling pathway, increasing protein synthesis and cell size. However, adenovirus-mediated overexpression of Pik3ip1 attenuated PI3K-mediated cardiac hypertrophy. Pik3ip1 was upregulated by PHH due to swimming training, but not by pathological cardiac hypertrophy (PAH) due to pressure-overload, suggesting that Pik3ip1 plays a compensatory negative role for PHH. Collectively, our results elucidate the mechanisms for the roles of Pik3ip1 in PI3K/AKT signaling pathway.

SUBMITTER: Song HK

PROVIDER: S-EPMC4380398 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Pik3ip1 modulates cardiac hypertrophy by inhibiting PI3K pathway.

Song Hong Ki HK Kim Jiyeon J Lee Jong Sub JS Nho Kyoung Jin KJ Jeong Hae Chang HC Kim Jihwa J Ahn Youngkeun Y Park Woo Jin WJ Kim Do Han DH

PloS one 20150331 3

Cardiac hypertrophy is an adaptive response to various physiological and pathological stimuli. Phosphoinositide-3 kinase (PI3K) is a highly conserved lipid kinase involved in physiological cardiac hypertrophy (PHH). PI3K interacting protein1 (Pik3ip1) shares homology with the p85 regulatory subunit of PI3K and is known to interact with the p110 catalytic subunit of PI3K, leading to attenuation of PI3K activity in liver and immune cells. However, the role of Pik3ip1 in the heart remains unknown. ...[more]

PMID: 25826393

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Project description:Cardiac hypertrophy is caused by cardiac volume or pressure overload conditions and ultimately leads to contractile dysfunction and heart failure. Oxytocin (OT), an endocrine nonapeptide, has been identified as a cardiovascular homeostatic hormone with anti-hypertrophic effects. However, the underlying mechanism remains elusive. In this study, we aimed to investigate the role and mechanism of OT in cardiac hypertrophy. The rats with cardiac hypertrophy induced by isoproterenol (ISO) were treated with or without oxytocin. Cardiac functional parameters were analyzed by echocardiography. The changes in cell surface area were observed using wheat germ agglutinin (WGA) or immunofluorescence staining. The expressions of cardiac hypertrophy markers (B-Natriuretic Peptide, BNP and β-myosin heavy chain, β-MHC), long non-coding RNA Growth (LcRNA) Arrest-Specific transcript 5 (lncRNA GAS5), miR-375-3p, and Kruppel-like factor 4 (Klf4) were detected by qRT-PCR. KLF4 protein and PI3K/AKT pathway related proteins were detected by Western blot. The interactions among lncRNA GAS5, miR-375-3p, and Klf4 were verified by dual-luciferase reporter assays. The findings showed that OT significantly attenuated cardiac hypertrophy, increased expressions of lncRNA GAS5 and KLF4, and decreased miR-375-3p expression. In vitro studies demonstrated that either knock-down of lncRNA GAS5 or Klf4, or over-expression of miR-375-3p blunted the anti-hypertrophic effects of OT. Moreover, down-regulation of lncRNA GAS5 promoted the expression of miR-375-3p and inhibited KLF4 expression. Similarly, over-expression of miR-375-3p decreased the expression of KLF4. Dual-luciferase reporter assays validated that lncRNA GAS5 could sponge miR-375-3p and Klf4 was a direct target gene of miR-375-3p. In addition, OT could inactivate PI3K/AKT pathway. The functional rescue experiments further identified OT regulated PI3K/AKT pathway through lncRNA GAS5/miR-375-3p/KLF4 axis. In summary, our study demonstrates that OT ameliorates cardiac hypertrophy by inhibiting PI3K/AKT pathway via lncRNA GAS5/miR-375-3p/KLF4 axis.

Dataset Information

Pik3ip1 modulates cardiac hypertrophy by inhibiting PI3K pathway.

Publications

Pik3ip1 modulates cardiac hypertrophy by inhibiting PI3K pathway.

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