目的:基因表达的转录调控在心脏发育和功能过程中协调复杂的形态发生和分子事件中起着至关重要的作用。介体复合物是控制真核细胞中基因表达的必需多亚基蛋白复合物。虽然介体亚基(MED)在复合体中整体工作,单个MED组件显示专用功能。MED27,归类为上尾亚基,具有尚未表征的功能。在这项研究中,我们旨在研究MED27在心肌细胞中的生理作用。
方法:我们生成了Med27floxed鼠标行,进一步用于产生组成型(cKO)和诱导型(icKO)心肌细胞特异性Med27敲除小鼠模型。形态学,在Med27cKO和icKO突变体中进行了组织学分析和心脏生理学研究。通过RNA测序(RNAseq)分析确定转录谱。
结果:在发育中的小鼠心肌细胞中消融MED27会导致胚胎致死,而其在成人心肌细胞中的缺失导致心力衰竭和死亡。类似于另一个上尾亚基的消融,心肌细胞中的MED30,MED27的缺失导致心肌细胞中大多数MED的蛋白质水平降低。有趣的是,MED30的过表达无法恢复MED27缺陷心肌细胞中Mediator亚基的蛋白质水平,证明MED27在维持介体复合物的完整性和稳定性方面的作用与MED30无关。
结论:我们的结果揭示了MED27通过维持介体核心的稳定性在心脏发育和功能中的重要作用。
OBJECTIVE: Transcriptional regulation of gene expression plays a crucial role in orchestrating complex morphogenetic and molecular events during heart development and function. Mediator complex is an essential multi-subunit protein complex that governs gene expression in eukaryotic cells. Although Mediator subunits (MEDs) work integrally in the complex, individual MED component displays specialized functions. MED27, categorized as an Upper Tail subunit, possesses an as-yet-uncharacterized function. In this study, we aimed to investigate the physiological role of MED27 in cardiomyocytes.
METHODS: we generated a Med27 floxed mouse line, which was further used to generate constitutive (cKO) and inducible (icKO) cardiomyocyte-specific Med27 knockout mouse models. Morphological, histological analysis and cardiac physiological studies were performed in Med27 cKO and icKO mutants. Transcriptional profiles were determined by RNA sequencing (RNAseq) analysis.
RESULTS: Ablation of MED27 in developing mouse cardiomyocytes results in embryonic lethality, while its deletion in adult cardiomyocytes leads to heart failure and mortality. Similar to the ablation of another Upper Tail subunit, MED30 in cardiomyocytes, deletion of MED27 leads to decreased protein levels of most MEDs in cardiomyocytes. Interestingly, overexpression of MED30 fails to restore the protein levels of Mediator subunits in MED27-deficient cardiomyocytes, demonstrating that the role of MED27 in maintaining the integrity and stability of the Mediator complex is independent of MED30.
CONCLUSIONS: Our results revealed an essential role of MED27 in cardiac development and function by maintaining the stability of the Mediator core.