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BMC Biol 2006 Feb 09;4:4. doi: 10.1186/1741-7007-4-4.
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CBFbeta is a facultative Runx partner in the sea urchin embryo.

Robertson AJ , Dickey-Sims C , Ransick A , Rupp DE , McCarthy JJ , Coffman JA .

BACKGROUND: Runx proteins are developmentally important metazoan transcription factors that form a heterodimeric complex with the non-homologous protein Core Binding Factor beta (CBFbeta). CBFbeta allosterically enhances Runx DNA binding but does not bind DNA itself. We report the initial characterization of SpCBFbeta, the heterodimeric partner of SpRunt-1 from the sea urchin Stronylocentrotus purpuratus. RESULTS: SpCBFbeta is remarkably similar to its mammalian homologues, and like them it enhances the DNA binding of the Runt domain. SpCBFbeta is entirely of zygotic provenance and its expression is similar that of SpRunt-1, accumulating globally at late blastula stage then later localizing to endoderm and oral ectoderm. Unlike SpRunt-1, however, SpCBFbeta is enriched in the endodermal mid- and hindgut of the pluteus larva, and is not highly expressed in the foregut and ciliated band. We showed previously that morpholino antisense-mediated knockdown of SpRunt-1 leads to differentiation defects, as well as to extensive post-blastula stage apoptosis caused by under-expression of the Runx target gene SpPKC1. In contrast, we show here that knockdown of SpCBFbeta does not negatively impact cell survival or SpPKC1 expression, although it does lead to differentiation defects similar to those associated with SpRunt-1 deficiency. Moreover, SpRunt-1 containing a single amino acid substitution that abolishes its ability to interact with SpCBFbeta retains the ability to rescue cell survival in SpRunt-1 morphant embryos. Chromatin immunoprecipitation shows that while the CyIIIa promoter engages both proteins, the SpPKC1 promoter only engages SpRunt-1. CONCLUSION: SpCBFbeta is a facultative Runx partner that appears to be required specifically for cell differentiation.

PubMed ID: 16469111
PMC ID: PMC1395345
Article link: BMC Biol
Grant support: [+]

Species referenced: Echinodermata
Genes referenced: arid3a cbfb CyIIIa impact LOC100887844 LOC115919910 LOC583082 pkcl2 runx2 SLBP
Antibodies: SLBP Ab1 cbfb Ab1 runx2 Ab1
Morpholinos: cbfb MO1

Article Images: [+] show captions
References [+] :
Adya, Function of CBFbeta/Bro proteins. 2001, Pubmed