Post-translational regulation of cellular nucleic acid binding protein during embryogenesis

LOMBARDO, V. A.; BORGOGNONE, M.; CALCATERRA, N. B.

Rosario, Santa Fe

Congreso; XLII Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology (SAIB).; 2006

Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB)

The zinc-finger cellular nucleic acid binding protein (CNBP) is a single-stranded nucleic acid binding protein essential for normal mouse and chicken forebrain development. We had reported that in amphibian and fish CNBP has a dual sub-cellular localization. CNBP amino acid sequences show putative proteolytic and phosphorylation sites. Phosphorylation and proteolysis are important post-translational modifications in embryogenesis. We showed that zebrafish CNBP (zCNBP) is differentially phosphorylated in vitro during embryogenesis by a cAMP-dependent protein kinase, reaching a maximum at 24 - 48 hours post-fertilization. Noteworthy, in these in vitro assays we saw that zCNBP protein level decreases at the time the phosphorylation begins to arise, suggesting that both phenomena could be related. Here, we analyzed by western blot assays the in vivo zCNBP proteolysis during zebrafish embryogenesis, observing the same pattern than in the in vitro assays. To analyze the possible relationship between both processes, we generated a zCNBP mutant not able to be phosphorylated by embryonic extracts. This mutant protein was proteolysed as the wild type zCNBP. This suggests that phosphorylation status of zCNBP may not be the signal to induce zCNBP proteolysis.