Protein kinase A is involved in the induction of early mesodermal marker genes by activin

• Published in: Mechanisms of development 1998-12, Vol.79 (1), p.5-15
• Main Authors: Joore, Jos, van de Water, Sandra, Betist, Marco, van den Eijnden-van Raaij, Adriana, Zivkovic, Danica
• Format: Article
• Language: English
• Subjects: 8-Bromo Cyclic Adenosine Monophosphate - pharmacology; Activin; Activins; Animals; Bacterial Proteins; Blastocyst - metabolism; Cyclic AMP-Dependent Protein Kinases - metabolism; Danio rerio; Drosophila Proteins; Embryo, Nonmammalian - drug effects; Embryo, Nonmammalian - metabolism; Enzyme Activation; Fetal Proteins - genetics; Fetal Proteins - metabolism; Gastrula - physiology; Gene Expression Regulation, Developmental; goosecoid; Goosecoid Protein; Homeodomain Proteins - genetics; Homeodomain Proteins - metabolism; Inhibins - metabolism; Inhibins - pharmacology; Mesoderm; Mesoderm - drug effects; Mesoderm - metabolism; no tail; Promoter Regions, Genetic; Protein kinase A; Repressor Proteins; Signal Transduction; T-Box Domain Proteins; Transcription Factors; Zebrafish; Zebrafish - embryology; Zebrafish Proteins
• ISSN: 0925-4773; 1872-6356
• 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-skipped1 remains unaltered. Overexpression of the catalytic subunit of PKA in embryos does not affect expression of goosecoid, no tail or even-skipped1. 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.