雌性素及雌性素接受體抑制PP1基因表現拮抗心肌細胞肥大之機轉研究

Inhibition of ISO- Induced Cardiomyoblast Hypertrophy By Estrogen And Estrogen Receptor-alpha Is Protein Phosphatase 1- Dependent

章家倩(Chia-Chien Chang)

指導教授 ： 黃志揚

中山醫學大學/醫學院/生化暨生物科技研究所/碩士(2006年)

https://doi.org/10.6834/CSMU.2006.00027

摘要

從文獻得知女性雌激素及其接受體能夠有效保護其免於心臟肥大的威脅，當停經後婦女接受適當荷爾蒙補充後其心臟肥大情形可被抑制，已知雌激素可透過抗氧化方式提供保護，然而雌激素究竟透過何種機轉直接保護心臟仍然不甚清楚。另外許多心臟病人是由於其β-adrenergic receptor過度被刺激活化，使Protein phosphatase 1(PP1)活性上升引發心肌肥大進而導致心臟病發生。因此本論文以Isoproterenol(ISO)這個β-receptor agonist刺激帶有Tet-on ER-α系統的H9c2細胞，誘導其肥大來模擬此類病人。同時在有Estrogen(E2)存在或過量表現ER-α情形下，發現E2、ER-α或加成處理會抑制ISO所誘導的細胞肥大，此現象會在ER拮抗劑ICI存在下而回復，並且ISO所導致的鈣離子囤積也會被抑制。此外PP1基因在mRNA及protein level的表現亦受到E2、ER-α影響而下降同時其下游蛋白ser16 P- PLB表現上升。接著為證實PP1表現量下降與細胞肥大被抑制有直接關係，以短暫轉殖將PP1cα送入細胞大量表現誘導肥大，之後處理E2、ER-α，結果發現肥大同樣受到抑制。因此，本論文證明雌性素經由其受體或單獨受體本身可透過抑制PP1基因表現進而抑制ISO所誘導之細胞肥大。

關鍵字

雌激素 ； 蛋白磷酸水解酶心血管 ； 心臟

並列摘要

Previous study suggests that estrogen could be opposed to the development of cardiac hypertrophy. However, the mechanisms of E2 action are obscure. Additionally, activation of serine/threonine protein phosphatase 1 (PP1) involves the cardiac hypertrophy induced by beta-adrenergic signaling. In this study, we treated H9c2 cardiomyoblast with isoproterenol (ISO) which stimulates β-adrenergic receptor and contributes to cardiomyocyte hypertrophy, which shares similarity to end-stage human heart failure. The results show that pretreatment of 17β-estradiol (E2), tet-on estrogen receptor-α, or both of them significantly prevented ISO-induced increased cell size, hypertrophy marker gene expression and cytosol calcium accumulation. Additionally, estrogen receptor antagonist (ICI) could reverse those effects, suggesting E2 action is partially through estrogen receptor. The same treatment also reduceed ISO-induced protein phosphatase1 (PP1) gene expression in mRNA and protein level, and increased the level of Ser-16 phosphorylated phospholamban(PLB), a downstream protein of protein phosphatase 1 and responsible for regulation of sarcoplasmic reticulum Ca2＋-ATPase (SERCA) activity. Furthermore, the causal link was strengthened when overexpressing PP1c alpha by transfection for induction of hypertrophy, same treatment also prevented it. Taken together, we suggest that estrogen and estrogen receptor-α inhibit cardiomyoblast hypertrophy through interfering protein phosphatase 1 (PP1) gene expression and its downstream signaling.

並列關鍵字

Estrogen ； PP1 ； Heart ； Estrogen receptor

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