核磷蛋白在心肌损伤中的作用及其调控机制研究

Nucleolar stress is an early response to myocardial damage involving nucleolar proteins nucleostemin and nucleophosmin. NPM delocalization from nucleoli is widely accepted as a marker of nucleolar stress in noncardiac cells We found that increased myocardial apoptosis and decreased cardiac function was demonstrated in ALDH2 knockout mice after endoplasmic reticulum stress induction. In addition, nucleophosmin (NPM) was inhibited in ALDH2 knockout mice compared with wildetype mice after tunicamycin challenges. Thus, we propose that NPM re-induction is a critical endogenous protectivie mechanism in stress-challenged myocardial cells. In addition, NPM expression is probably regulated by ALDH2, which also protect cardiomyocytes from apoptosis induced by inhibition of NPM. To test this hypothesis, NPM expression is determined after tunicamycin challenges using ALDH2 knockout mice and ALDH2 adenovirus. Data may verify the notion that ALDH2 play a protective role by upregulating NPM. A small molecule inhibitor of NPM is used to establish injury model using wild-type and ALDH2 knock mice. Apoptosis and cardiac function are determined after NPM inhibition. p53 and related signaling pathways are also investigated after NPM inhibition. The protein levels of NPM are detected using end-stage diseased hearts to further clarify the role of NPM in heart disease. The purpose of this study is to clarify the role of NPM in myocardial injury and explore a novel target for intervention in heart disease.

核仁应激被认为是心肌损伤的一种早期应答方式，核磷蛋白（NPM)在核仁内外的易位是核仁应激的标志之一。我们采用内质网应激模型发现ALDH2缺失小鼠心肌细胞凋亡增多、心脏功能减低，NPM上调受抑制，由此提出：NPM在心肌损伤时表达上调是心肌细胞内在的保护机制，而ALDH2能够调控NPM表达以及NPM抑制后所致细胞凋亡，为验证此假说，本研究拟建立内质网应激损伤模型，采用ALDH2敲除小鼠及ALDH2腺病毒，观察NPM在心肌损伤时的表达差异，通过NPM小分子抑制剂验证ALDH2通过上调NPM发挥保护性作用；采用野生型和ALDH2敲除小鼠，建立NPM抑制剂损伤模型，观察NPM抑制后小鼠心脏功能、p53及相关信号通路的变化；检测终末期病变心脏NPM变化，了解NPM在心脏疾病中的作用。本研究旨在阐明核磷蛋白在心肌损伤中的作用，探索干预心脏疾病的新靶点，为临床治疗提供新手段。

核仁应激被认为是心肌损伤的一种早期应答方式，核磷蛋白（NPM)在核仁内外的易位是核仁应激的标志之一。本课题采用NPM小分子抑制剂NSC348884模拟核仁应激，证实NSC348884诱导心肌细胞Bax、cleaved Caspase3、cleaved PARP表达升高，Bcl2表达减低诱导，结合Annexin V流式细胞分析结果提示NSC348884增加心肌细胞凋亡，ALDH2可能通过p38 MAPK通路减少NSC348884诱导的心肌细胞凋亡，此外，NSC348884促使野生型小鼠离体心肌细胞收缩功能减低，而NSC348884干预后，ALDH2敲除小鼠离体细胞心肌收缩功能明显较野生型明显减低，表现为PS、± dL/dt及TR90等机械参数显著减低，本研究结果提示ALDH2是调控核仁应激的关键信号分子之一，进一步深化了ALDH2对心肌保护性作用机制的研究，为我们寻找心脏疾病的治疗新靶点提供理论依据。