Joore J, van de Water S, Betist M, van den Eijnden-van Raaij A, Zivkovic D
Hubrecht Laboratory, The Netherlands Institute for Developmental Biology, Utrecht, The Netherlands.
Mech Dev. 1998 Dec;79(1-2):5-15. doi: 10.1016/s0925-4773(98)00152-x.
In this study we have investigated the role of cAMP-dependent protein kinase A (PKA) in the induction of the early mesodermal marker genes goosecoid and no tail by activin in zebrafish embryos. We show that upon treatment with activin, zebrafish blastula cells exhibit a rapid and transient increase in PKA activity. In these cells, activin rapidly induces the expression of the immediate early response genes goosecoid and no tail. Stimulation and inhibition of PKA by activin, respectively, enhances and reduces the induction of goosecoid and no tail mRNA expression. Similar effects of PKA stimulation and inhibition on the induction by activin of a 1.8 kb zebrafish goosecoid promoter construct were observed. The induction by activin of a fragment of the zebrafish goosecoid promoter that mediates an immediate early response to activin is blocked by inhibition of PKA. Activation of PKA alone has no effect in these experiments. Finally, inhibition of PKA in whole embryos by overexpression of a dominant negative regulatory subunit of PKA reduces the expression of no tail and goosecoid, whereas the expression of even-skippedl remains unaltered. Overexpression of the catalytic subunit of PKA in embryos does not affect expression of goosecoid, no tail or even-skippedl. These data show that in dissociated blastulae, PKA is required, but not sufficient for activin signalling towards induction of goosecoid and no tail. In intact zebrafish embryos, PKA contributes to induction of goosecoid and no tail, although it is not required or sufficient.
在本研究中，我们探究了环磷酸腺苷（cAMP）依赖性蛋白激酶A（PKA）在激活素诱导斑马鱼胚胎早期中胚层标记基因鹅膏蕈氨酸和无尾基因表达过程中的作用。我们发现，用激活素处理后，斑马鱼囊胚细胞中的PKA活性迅速且短暂地增加。在这些细胞中，激活素能快速诱导即时早期反应基因鹅膏蕈氨酸和无尾基因的表达。激活素分别对PKA的刺激和抑制，增强和降低了鹅膏蕈氨酸和无尾基因mRNA表达的诱导。观察到PKA刺激和抑制对激活素诱导1.8 kb斑马鱼鹅膏蕈氨酸启动子构建体也有类似影响。激活素对介导对激活素即时早期反应的斑马鱼鹅膏蕈氨酸启动子片段的诱导作用，会被PKA抑制所阻断。在这些实验中，单独激活PKA没有效果。最后，通过过表达PKA的显性负调控亚基来抑制全胚胎中的PKA，会降低无尾基因和鹅膏蕈氨酸的表达，而偶数跳变基因1的表达则保持不变。在胚胎中过表达PKA的催化亚基不会影响鹅膏蕈氨酸、无尾基因或偶数跳变基因1的表达。这些数据表明，在解离的囊胚中，PKA是激活素向鹅膏蕈氨酸和无尾基因诱导信号传导所必需的，但并不充分。在完整的斑马鱼胚胎中，PKA有助于鹅膏蕈氨酸和无尾基因的诱导，尽管它并非必需或充分条件。
