Rbpms2 prevents major cardiac defects in cardiomyocyte-specific Rbpms-deficient mice

Cell type-specific splicing depends on RNA-binding splicing factors. Several important splicing factors were identified in cardiomyocytes, including members of the RBPMS family, but their role during heart development has not been fully characterized. Here, we demonstrate that the function of RBPMS overlaps with the closely related paralogue RBPMS2. Rbpms-deficient cardiomyocytes exhibit a higher degree of binucleation but this does not impair heart function in mice within the first year after birth. In contrast, Rbpms/Rbpms2 (Rbpms/2) compound mutants show a pronounced disruption of the splicing network in embryonic cardiomyocytes, which lead to formation of defective nuclei and disruption of sarcomere structures, eventually resulting in embryonic lethality. We demonstrate that mitotic defects in embryonic Rbpms/2-deficient cardiomyoctes are caused by the disbalance of nuclear and cytoplasmic Camk2g isoforms. Overexpression of the Rbpmsa isoform partially rescues these defects, preventing embryonic lethality of Rbpms/2-deficient mice, and is sufficient for cardiomyocyte-specific splicing in other cell types.
The file contains images of non-processed blots for the western blot analysis.

细胞类型特异性可变剪接依赖于RNA结合型剪接因子（RNA-binding splicing factors）。研究人员已在心肌细胞（cardiomyocytes）中鉴定出多种关键剪接因子，其中包括RBPMS家族（RBPMS family）成员，但其在心脏发育过程中的功能尚未得到完整阐释。本研究证实，RBPMS与其亲缘关系紧密的旁系同源基因RBPMS2存在功能重叠。Rbpms基因缺陷的心肌细胞呈现更高比例的双核化现象，但该现象并不会损伤小鼠出生后一年内的心脏功能。与之相反，Rbpms/Rbpms2（简称Rbpms/2）复合突变体的胚胎心肌细胞剪接调控网络会出现显著紊乱，进而引发异常细胞核形成、肌节结构破坏，最终导致胚胎致死。本研究发现，胚胎期Rbpms/2缺陷心肌细胞的有丝分裂缺陷（mitotic defects）由细胞核与细胞质中Camk2g同工型（Camk2g isoforms）的表达失衡所导致。过表达Rbpmsa同工型可部分挽救上述缺陷，阻止Rbpms/2缺陷小鼠发生胚胎致死，且足以在其他细胞类型中实现心肌细胞特异性的可变剪接调控。
本数据集包含蛋白质免疫印迹（Western blot）分析所用的未处理原始印迹图像。