Identification of protein domains required for makorin-2-mediated neurogenesis inhibition in Xenopus embryos

Biochem Biophys Res Commun. 2010 Mar 26;394(1):18-23. doi: 10.1016/j.bbrc.2010.02.041. Epub 2010 Feb 16.

Abstract

Makorin-2, consisting of four highly conserved C(3)H zinc fingers, a Cys-His motif and a C(3)HC(4) RING zinc finger domain, is a putative ribonucleoprotein. We have previously reported that Xenopus makorin-2 (mkrn2) is a neurogenesis inhibitor acting upstream of glycogen synthase kinase-3beta (GSK-3beta) in the phosphatidylinositol 3-kinase/Akt pathway. In an effort to identify the functional domains required for its anti-neurogenic activity, we designed and constructed a series of N- and C-terminal truncation mutants of mkrn2. Concurred with the full-length mkrn2, we showed that overexpression of one of the truncation mutants mkrn2(s)-7, which consists of only the third C(3)H zinc finger, Cys-His motif and C(3)HC(4) RING zinc finger, is essential and sufficient to produce the phenotypical dorso-posterior deficiencies and small-head/short-tail phenotype in tadpoles. In animal cap explant assay, we further demonstrated that mkrn2(s)-7 not only inhibits activin and retinoic acid-induced animal cap neuralization and the expression of a pan-neural marker neural cell adhesion molecule, but also induces GSK-3beta expression. These results collectively suggest that the third C(3)H zinc finger, Cys-His motif and C(3)HC(4) RING zinc finger are indispensable for the anti-neurogenic activity of mkrn2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs / genetics
  • Animals
  • Conserved Sequence
  • Embryo, Nonmammalian / metabolism
  • Glycogen Synthase Kinase 3 / metabolism
  • Neurogenesis*
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism
  • Phylogeny
  • Protein Structure, Tertiary / genetics
  • Ribonucleoproteins / classification
  • Ribonucleoproteins / genetics
  • Ribonucleoproteins / metabolism*
  • Xenopus Proteins / classification
  • Xenopus Proteins / genetics
  • Xenopus Proteins / metabolism*
  • Xenopus laevis / embryology*
  • Xenopus laevis / genetics
  • Xenopus laevis / metabolism
  • Zinc Fingers / genetics

Substances

  • Mkrn2 protein, Xenopus
  • Phosphoproteins
  • Ribonucleoproteins
  • Xenopus Proteins
  • ZFP36 protein, Xenopus
  • Glycogen Synthase Kinase 3