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EMBO J October 27, 2004; 23 (21): 4190-201.

The polarity-inducing kinase Par-1 controls Xenopus gastrulation in cooperation with 14-3-3 and aPKC.

Par (partitioning-defective) genes were originally identified in Caenorhabditis elegans as determinants of anterior/posterior polarity. However, neither their function in vertebrate development nor their action mechanism has been fully addressed. Here we show that two members of Par proteins, 14-3-3 (Par-5) and atypical PKC (aPKC), regulate the serine/threonine kinase Par-1 to control Xenopus gastrulation. We find first that Xenopus Par-1 (xPar-1) is essential for gastrulation but not for cell fate specification during early embryonic development. We then find that xPar-1 binds to 14-3-3 in an aPKC-dependent manner. Our analyses identify two aPKC phosphorylation sites in xPar-1, which are essential for 14-3-3 binding and for proper gastrulation movements. The aPKC phosphorylation-dependent binding of xPar-1 to 14-3-3 does not markedly affect the kinase activity of xPar-1, but induces relocation of xPar-1 from the plasma membranes to the cytoplasm. Finally, we show that Xenopus aPKC and its binding partner Xenopus Par-6 are also essential for gastrulation. Thus, our results identify a requirement of Par proteins for Xenopus gastrulation and reveal a novel interrelationship within Par proteins that may provide a general mechanism for spatial control of Par-1.

PubMed ID: 15343271
PMC ID: PMC524384
Article link: EMBO J

Genes referenced: mark2 mark3 prkci
Morpholinos: ctnnb1 MO1 mark2 MO1 pard6b MO1

References [+] :
Amaya, Expression of a dominant negative mutant of the FGF receptor disrupts mesoderm formation in Xenopus embryos. 1991, Pubmed, Xenbase

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