通过RNA结合蛋白(RBP)调节RNA稳定性和翻译是改变基因表达的关键过程。已知包含Msi1和Msi2的RBP的Musashi家族控制RNA稳定性和翻译。然而,尽管心脏中存在MSI2,它的功能在很大程度上仍然未知。这里,我们旨在探讨MSI2的心功能。我们证实了成年小鼠中存在MSI2,老鼠的心脏,和新生大鼠心肌细胞。此外,Msi2在心脏心肌细胞部分中显著富集。接下来,使用RNA-seq数据和同工型特异性PCR引物,我们鉴定了Msi2同工型1,4和5,以及标记为Msi26和7的两个新的推定同工型在心脏中表达.Msi2亚型的过表达导致培养的心肌细胞中的心脏肥大。此外,Msi2在心脏肥大的压力超负荷模型中表现出显着增加。我们选择了同工型4和7来验证由于其独特的可变剪接模式而产生的肥大效应。AAV9介导的Msi2亚型4和7在小鼠心脏中的过表达导致心脏肥大,膨胀,心力衰竭,最终早逝,确认Msi2的病理功能。利用全球蛋白质组学,基因本体论,透射电子显微镜,海马,和跨膜电位测量分析,发现增加的MSI2导致心脏线粒体功能障碍。机械上,我们确定Cluh和Smyd1为Msi2的直接下游靶标。Cluh和Smyd1的过表达抑制Msi2诱导的心脏功能障碍和线粒体功能障碍。总的来说,我们显示Msi2诱导肥大,线粒体功能障碍,和心力衰竭。
Regulation of RNA stability and translation by RNA-binding proteins (RBPs) is a crucial process altering gene expression. Musashi family of RBPs comprising Msi1 and Msi2 is known to control RNA stability and translation. However, despite the presence of
MSI2 in the heart, its function remains largely unknown. Here, we aim to explore the cardiac functions of
MSI2. We confirmed the presence of MSI2 in the adult mouse, rat heart, and neonatal rat cardiomyocytes. Furthermore,
Msi2 was significantly enriched in the heart cardiomyocyte fraction. Next, using RNA-seq data and isoform-specific PCR primers, we identified Msi2 isoforms 1, 4, and 5, and two novel putative isoforms labeled as
Msi2 6 and 7 to be expressed in the heart. Overexpression of Msi2 isoforms led to cardiac hypertrophy in cultured cardiomyocytes. Additionally, Msi2 exhibited a significant increase in a pressure-overload model of cardiac hypertrophy. We selected isoforms 4 and 7 to validate the hypertrophic effects due to their unique alternative splicing patterns. AAV9-mediated overexpression of Msi2 isoforms 4 and 7 in murine hearts led to cardiac hypertrophy, dilation, heart failure, and eventually early death, confirming a pathological function for Msi2. Using global proteomics, gene ontology, transmission electron microscopy, seahorse, and transmembrane potential measurement assays, increased MSI2 was found to cause mitochondrial dysfunction in the heart. Mechanistically, we identified Cluh and Smyd1 as direct downstream targets of
Msi2. Overexpression of Cluh and Smyd1 inhibited Msi2-induced cardiac malfunction and mitochondrial dysfunction. Collectively, we show that Msi2 induces hypertrophy, mitochondrial dysfunction, and heart failure.