Notch inhibits Ptf1 function and acinar cell differentiation in developing mouse and zebrafish pancreas
Notch inhibits Ptf1 function and acinar cell differentiation in developing mouse and zebrafish pancreas
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DOI：
10.1242/dev.01280
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发表时间：
2004-09-01
期刊：
影响因子：
4.6
通讯作者：
Leach, SD
中科院分区：
文献类型：
--
作者：
Esni, F;Ghosh, B;Leach, SD
Noch信号调节多种成人和胚胎组织中的细胞命运决定，并代表外分泌型胰腺癌的一个特征。在小鼠胰腺发育过程中，Notch途径的靶向失活已经明确了Notch在调节早期内分泌分化中的作用，但关于Notch在调节随后的外分泌分化事件中可能扮演的角色，提供的信息较少。在这里，我们展示了激活的Notch和Notch靶基因积极地抑制发育中的小鼠和斑马鱼胰腺腺泡细胞分化程序的完成。在发育中的小鼠胰腺中，Notch靶基因Hes1与Ptf1-P48在外分泌前体细胞中共表达，但在分化的淀粉酶阳性的腺泡细胞中不表达。用慢病毒载体系统诱导E10.5小鼠背部胰腺芽外植体培养中异位Notch通路的激活，我们发现Hes1和Notch1-IC都以细胞自主的方式抑制腺泡细胞的分化，但不抑制Ptf1-P48的表达。异位Notch激活也延缓了斑马鱼胰腺发育中腺泡细胞的分化。内源性Notch在调节胰腺外分泌分化中的作用的进一步证据是通过对带有纯合子思维炸弹突变的斑马鱼胚胎的检查提供的，在这种突变中，Notch信号被扰乱。与野生型杂合体对照相比，智力炸弹缺陷的胚胎表现出外分泌胰腺的加速分化。无毛[SU(H)]结构的显性-负性抑制因子的表达也诱导了类似的表型，证实了Notch在斑马鱼胰腺发育过程中有效地抑制了腺泡细胞的分化。通过瞬时转染Ptf1应答报告基因，我们进一步证明了Notch和Notch/SU(H)靶基因直接抑制Ptf1活性，而不依赖于Ptf1组分蛋白表达的变化。这些结果确定了Notch在调节胰腺外分泌分化中的正常抑制作用。
Notch signaling regulates cell fate decisions in a variety of adult and embryonic tissues, and represents a characteristic feature of exocrine pancreatic cancer. In developing mouse pancreas, targeted inactivation of Notch pathway components has defined a role for Notch in regulating early endocrine differentiation, but has been less informative with respect to a possible role for Notch in regulating subsequent exocrine differentiation events. Here, we show that activated Notch and Notch target genes actively repress completion of an acinar cell differentiation program in developing mouse and zebrafish pancreas. In developing mouse pancreas, the Notch target gene Hes1 is co-expressed with Ptf1-P48 in exocrine precursor cells, but not in differentiated amylase-positive acinar cells. Using lentiviral delivery systems to induce ectopic Notch pathway activation in explant cultures of E10.5 mouse dorsal pancreatic buds, we found that both Hes1 and Notch1-IC repress acinar cell differentiation, but not Ptf1-P48 expression, in a cell-autonomous manner. Ectopic Notch activation also delays acinar cell differentiation in developing zebrafish pancreas. Further evidence of a role for endogenous Notch in regulating exocrine pancreatic differentiation was provided by examination of zebrafish embryos with homozygous mindbomb mutations, in which Notch signaling is disrupted. mindbomb-deficient embryos display accelerated differentiation of exocrine pancreas relative to wild-type clutchmate controls. A similar phenotype was induced by expression of a dominant-negative Suppressor of Hairless [Su(H)] construct, confirming that Notch actively represses acinar cell differentiation during zebrafish pancreatic development. Using transient transfection assays involving a Ptf1-responsive reporter gene, we further demonstrate that Notch and Notch/Su(H) target genes directly inhibit Ptf1 activity, independent of changes in expression of Ptf1 component proteins. These results define a normal inhibitory role for Notch in the regulation of exocrine pancreatic differentiation.