Myosin phosphatase targeting subunit 1 (Mypt1) is the regulatory subunit of myosin phosphatase which dephosphorylates the light chain of myosin II to inhibit its contraction. Although biochemical properties of Mypt1 have been characterized in detail, its biological functions in organisms are not well understood. The zebrafish mypt1 ^sq181 allele was found defective in the ventral pancreatic bud and extrapancreatic duct development, resulting in dysplasia of exocrine pancreas. In mypt1 ^sq181 mutant, the early growth of the ventral pancreatic bud was initiated but failed to expand due to impaired cell proliferation and increased cell apoptosis. As Mypt1 is essential for cell migration, the loss‐of‐function of Mypt1 in the mutant disrupted the lateral plate mesoderm migration during gut looping, therefore, altering the Bmp2a expression pattern within it, and eventually leading to impaired Bmp signaling in the adjacent exocrine pancreas. Overexpression of bmp2a could rescue the development of exocrine pancreas, suggesting that the impaired Bmp2a signaling is responsible for the pancreatic development defects. Bmp2a has been reported to promote the early specification of the ventral pancreatic bud, and our study reveals that it continues to serve as a cell proliferation/survival signal to ensure pancreatic bud growth properly in zebrafish.

中文翻译：

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Mypt1调节Bmp信号，以促进斑马鱼中胚胎外分泌胰腺的生长。

靶向肌球蛋白磷酸酶的亚基1（Mypt1）是肌球蛋白磷酸酶的调节性亚基，可将肌球蛋白II的轻链去磷酸化以抑制其收缩。尽管Mypt1的生化特性已被详细描述，但其在生物中的生物学功能尚不十分清楚。斑马鱼mypt1 ^sq181等位基因在腹侧胰芽和胰外导管发育中发现缺陷，导致外分泌胰腺发育异常。在mypt1 ^sq181 突变，腹胰芽的早期生长开始，但由于细胞增殖受损和细胞凋亡增加而未能扩大。由于Mypt1对细胞迁移至关重要，因此突变体中Mypt1的功能丧失会破坏肠道循环过程中侧板中胚层的迁移，因此会改变其中的Bmp2a表达模式，并最终导致相邻外分泌物中Bmp信号传导受损。胰腺。bmp2a的过表达可以挽救外分泌胰腺的发育，这表明受损的Bmp2a信号是造成胰腺发育缺陷的原因。据报道，Bmp2a促进了腹胰芽的早期规格，我们的研究表明，Bmp2a继续充当细胞增殖/存活信号，以确保斑马鱼中胰腺芽的正常生长。