Abstract：
UNASSIGNED: Heart failure (HF) is a leading cause of morbidity and mortality worldwide. RNA-binding proteins are identified as regulators of cardiac disease; DDX5 (dead-box helicase 5) is a master regulator of many RNA processes, although its function in heart physiology remains unclear.
UNASSIGNED: We assessed DDX5 expression in human failing hearts and a mouse HF model. To study the function of DDX5 in heart, we engineered cardiomyocyte-specific Ddx5 knockout mice. We overexpressed DDX5 in cardiomyocytes using adeno-associated virus serotype 9 and performed transverse aortic constriction to establish the murine HF model. The mechanisms underlined were subsequently investigated using immunoprecipitation-mass spectrometry, RNA-sequencing, alternative splicing analysis, and RNA immunoprecipitation sequencing.
UNASSIGNED: We screened transcriptome databases of murine HF and human dilated cardiomyopathy samples and found that DDX5 was significantly downregulated in both. Cardiomyocyte-specific deletion of Ddx5 resulted in HF with reduced cardiac function, an enlarged heart chamber, and increased fibrosis in mice. DDX5 overexpression improved cardiac function and protected against adverse cardiac remodeling in mice with transverse aortic constriction-induced HF. Furthermore, proteomics revealed that DDX5 is involved in RNA splicing in cardiomyocytes. We found that DDX5 regulated the aberrant splicing of Ca2+/calmodulin-dependent protein kinase IIδ (CamkIIδ), thus preventing the production of CaMKIIδA, which phosphorylates L-type calcium channel by serine residues of Cacna1c, leading to impaired Ca2+ homeostasis. In line with this, we found increased intracellular Ca2+ transients and increased sarcoplasmic reticulum Ca2+ content in DDX5-depleted cardiomyocytes. Using adeno-associated virus serotype 9 knockdown of CaMKIIδA partially rescued the cardiac dysfunction and HF in Ddx5 knockout mice.
UNASSIGNED: These findings reveal a role for DDX5 in maintaining calcium homeostasis and cardiac function by regulating alternative splicing in cardiomyocytes, identifying the DDX5 as a potential target for therapeutic intervention in HF.
UNASSIGNED: We assessed DDX5 expression in human failing hearts and a mouse HF model. To study the function of DDX5 in heart, we engineered cardiomyocyte-specific Ddx5 knockout mice. We overexpressed DDX5 in cardiomyocytes using adeno-associated virus serotype 9 and performed transverse aortic constriction to establish the murine HF model. The mechanisms underlined were subsequently investigated using immunoprecipitation-mass spectrometry, RNA-sequencing, alternative splicing analysis, and RNA immunoprecipitation sequencing.
UNASSIGNED: We screened transcriptome databases of murine HF and human dilated cardiomyopathy samples and found that DDX5 was significantly downregulated in both. Cardiomyocyte-specific deletion of Ddx5 resulted in HF with reduced cardiac function, an enlarged heart chamber, and increased fibrosis in mice. DDX5 overexpression improved cardiac function and protected against adverse cardiac remodeling in mice with transverse aortic constriction-induced HF. Furthermore, proteomics revealed that DDX5 is involved in RNA splicing in cardiomyocytes. We found that DDX5 regulated the aberrant splicing of Ca2+/calmodulin-dependent protein kinase IIδ (CamkIIδ), thus preventing the production of CaMKIIδA, which phosphorylates L-type calcium channel by serine residues of Cacna1c, leading to impaired Ca2+ homeostasis. In line with this, we found increased intracellular Ca2+ transients and increased sarcoplasmic reticulum Ca2+ content in DDX5-depleted cardiomyocytes. Using adeno-associated virus serotype 9 knockdown of CaMKIIδA partially rescued the cardiac dysfunction and HF in Ddx5 knockout mice.
UNASSIGNED: These findings reveal a role for DDX5 in maintaining calcium homeostasis and cardiac function by regulating alternative splicing in cardiomyocytes, identifying the DDX5 as a potential target for therapeutic intervention in HF.
摘要：
心力衰竭(HF)是全球发病率和死亡率的主要原因。RNA结合蛋白被确定为心脏疾病的调节因子；DDX5（死盒解旋酶5）是许多RNA过程的主要调节因子，尽管其在心脏生理学中的功能尚不清楚。
我们评估了人衰竭心脏和小鼠HF模型中的DDX5表达。为了研究DDX5在心脏中的功能，我们设计了心肌细胞特异性Ddx5基因敲除小鼠。我们使用腺相关病毒血清型9在心肌细胞中过表达DDX5，并进行横向主动脉缩窄以建立小鼠HF模型。随后使用免疫沉淀-质谱法研究了下划线的机制，RNA测序，选择性剪接分析，和RNA免疫沉淀测序。
■我们筛选了鼠HF和人扩张型心肌病样本的转录组数据库，发现DDX5在两者中均显著下调。Ddx5的心肌细胞特异性缺失导致心脏功能降低的HF,扩大的心腔,和增加小鼠的纤维化。DDX5过表达改善了患有横主动脉缩窄诱导的HF的小鼠的心脏功能并防止了不利的心脏重塑。此外，蛋白质组学研究表明DDX5参与心肌细胞的RNA剪接。我们发现DDX5调节Ca2+/钙调蛋白依赖性蛋白激酶IIδ(CamkIIδ)的异常剪接,从而阻止CaMKIIδA的产生，它通过Cacna1c的丝氨酸残基磷酸化L型钙通道，导致Ca2+稳态受损。与此相符,我们发现DDX5耗竭心肌细胞细胞内Ca2+瞬变增加,肌浆网Ca2+含量增加.使用CaMKIIδA的腺相关病毒血清型9敲除部分挽救了Ddx5敲除小鼠的心脏功能障碍和HF。
■这些发现揭示了DDX5通过调节心肌细胞的可变剪接在维持钙稳态和心脏功能方面的作用，确定DDX5作为HF治疗干预的潜在目标。
我们评估了人衰竭心脏和小鼠HF模型中的DDX5表达。为了研究DDX5在心脏中的功能，我们设计了心肌细胞特异性Ddx5基因敲除小鼠。我们使用腺相关病毒血清型9在心肌细胞中过表达DDX5，并进行横向主动脉缩窄以建立小鼠HF模型。随后使用免疫沉淀-质谱法研究了下划线的机制，RNA测序，选择性剪接分析，和RNA免疫沉淀测序。
■我们筛选了鼠HF和人扩张型心肌病样本的转录组数据库，发现DDX5在两者中均显著下调。Ddx5的心肌细胞特异性缺失导致心脏功能降低的HF,扩大的心腔,和增加小鼠的纤维化。DDX5过表达改善了患有横主动脉缩窄诱导的HF的小鼠的心脏功能并防止了不利的心脏重塑。此外，蛋白质组学研究表明DDX5参与心肌细胞的RNA剪接。我们发现DDX5调节Ca2+/钙调蛋白依赖性蛋白激酶IIδ(CamkIIδ)的异常剪接,从而阻止CaMKIIδA的产生，它通过Cacna1c的丝氨酸残基磷酸化L型钙通道，导致Ca2+稳态受损。与此相符,我们发现DDX5耗竭心肌细胞细胞内Ca2+瞬变增加,肌浆网Ca2+含量增加.使用CaMKIIδA的腺相关病毒血清型9敲除部分挽救了Ddx5敲除小鼠的心脏功能障碍和HF。
■这些发现揭示了DDX5通过调节心肌细胞的可变剪接在维持钙稳态和心脏功能方面的作用，确定DDX5作为HF治疗干预的潜在目标。
