PDF(Pubmed)
Abstract：
In zebrafish (Danio rerio), iridophores are specified from neural crest cells and represent a tractable system for examining mechanisms of cell fate and differentiation. Using this system, we have investigated the role of cAMP protein kinase A (PKA) signaling in pigment cell differentiation. Activation of PKA with the adenylyl cyclase activator forskolin reduces the number of differentiated iridophores in wildtype larvae, with insignificant changes to melanophore number. Inhibition of PKA with H89 significantly increases iridophore number, supporting a specific role for PKA during iridophore development. To determine the effects of altering PKA activity on iridophore and melanophore gene expression, we examined expression of iridophore marker pnp4a, melanophore marker mitfa, and the mitfa repressor foxd3. Consistent with our cell counts, forskolin significantly decreased pnp4a expression as detected by in situ hybridization and quantification of pnp4a+ cells. Forskolin had the opposite effect on mitfa and foxd3 gene activity, increasing the area of expression. As mitfa/nacre mutants have extra iridophores as compared to wildtype larvae, we examined the function of mitfa during PKA-sensitive iridophore development. Forskolin treatment of mitfa/nacre mutants did significantly reduce the number of iridophores but to a lesser extent than that observed in treated wildtype larvae. Taken together, our data suggests that PKA inhibits iridophore development in a subset of iridophore precursors, potentially via a foxd3-independent pathway.
摘要：
在斑马鱼（Daniorerio）中，iridophores是从神经c细胞中指定的，代表了一种用于检查细胞命运和分化机制的可处理系统。使用这个系统，我们研究了cAMP蛋白激酶A（PKA）信号在色素细胞分化中的作用。用腺苷酸环化酶激活剂毛喉素激活PKA可减少野生型幼虫中分化的虹膜数量，黑素细胞数变化不明显。用H89抑制PKA显着增加虹膜数量，支持PKA在iridophore发育过程中的特定作用。为了确定改变PKA活性对虹膜和黑色素基因表达的影响，我们检查了虹膜标记pnp4a的表达，黑素细胞标记mitfa,和mitfa阻遏物foxd3.与我们的细胞计数一致，通过原位杂交和pnp4a细胞定量检测，毛喉素显着降低了pnp4a的表达。Forskolin对mitfa和foxd3基因活性有相反的影响，增加表达面积。由于mitfa/nacre突变体与野生型幼虫相比具有额外的虹膜，我们研究了mitfa在PKA敏感的虹膜细胞发育过程中的功能。毛喉素处理mitfa/nacre突变体确实显着减少了虹膜数量，但程度低于处理过的野生型幼虫。一起来看,我们的数据表明，PKA抑制了一个子集的虹膜前体细胞的发展，可能通过不依赖foxd3的途径。
