Elucidation fo molecular mechanism of pancreatic befa ceel differentiation using fissue-specific koock-out mice for the regeneration of beta ceas

我们将Rbp-j与Pdx杂交，使Rbp-j失活。或者Rip。转基因小鼠。在胰腺发育初期，Rbp-j的缺失导致α和PP细胞的加速分化，同时在E11.5时，Ngn3阳性细胞的数量减少。E15时可见表达导管细胞标记物的细长管状结构；然而，腺泡细胞和所有类型的内分泌细胞的分化都减少了。在胚胎后期，观察到代偿性腺泡细胞分化。由此产生的小鼠表现为胰岛素缺乏型糖尿病，同时伴有内分泌和外分泌胰腺发育不全。相反，β细胞中特异性Rbp-j的缺失并不影响β细胞的数量和功能。我们还使用Ptfla在表达Ptfla的细胞中产生了Rbp-j基因失活的小鼠。cre老鼠。cre介导的Rbp-j(f/f) Ptfla缺失的时间。cre小鼠比Rbp-j(f/f) Pdx晚1 d。cre老鼠。在Rbp-j(f/f) Ptfla中。cre小鼠胰腺，在E13.5时，Hesl表达降低伴随着上皮生长减少，但早期内分泌细胞分化最小。在E15.5时，Pdxl表达被抑制，腺泡细胞分化减少，但在出生期间观察到腺泡细胞增殖增加。因此，我们的分析表明，Notch/Rbp-j信号通路在胰腺早期发育过程中阻止胰腺祖细胞过早分化为内分泌细胞和导管细胞。我们的研究表明，Rbp-j除了在预防早期内分泌细胞过早分化中发挥作用外，还在胰腺中期发育过程中调节上皮生长、Pdxl表达和腺泡细胞分化。

We inactivated Rbp-j by crossing Rbp-j floxed mice with Pdx. cre or Rip.cre transgenic mice. The loss of Rbp-j at the initial stage of pancreatic development induced accelerated alpha and PP cell differentiation and a concomitant decrease in the number of Neurogenin3 (Ngn3)-positive cells at E11.5. Then at E15, elongated tubular structures expressing ductal cell markers were evident; however, differentiation of acinar and all types of endocrine cells were reduced During later embryonic stages, compensatory acinar cell dfferentiation was observed The resultant mice exhibited insulin-deficient diabetes with both endocrine and exocrine pancreatic hypoplasia In contrast, the loss of Rbp-j specifically in beta cells did not affect bete cell number and function.We also generated mice in which the Rbp-j gene was inactivated in Ptfla-expressing cells using Ptfla.cre mice. The timing of the Cre-mediated deletion in Rbp-j(f/f) Ptfla.cre mice is 1 day later than that in Rbp-j(f/f) Pdx.cre mice. In Rbp-j(f/f) Ptfla.cre mouse pancreases, at E13.5, the reduced Hesl expression was accompanied by reduced epithelial growth, but premature endocrine cell differentiation was minimal. At E15.5, Pdxl expression was repressed and acinar cell differentiation was reduced, but an increase in acinar cell proliferation was observed during the per natal period. Thus, our analyses indicate that Notch/Rbp-j signaling prevents premature differentiation of pancreatic progenitor cells into endocrine and ductal cells during early development of the pancreas.Our study indicates that in addition to its role in preventing premature differentiation of early endocrine cells, Rbp-j regulates epithelial growth, Pdxl expression, and acinar cell differentiation during mid-pancreatic development.