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Hum Mol Genet 2013 Sep 01;2217:3568-82. doi: 10.1093/hmg/ddt211.
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Bcl6a function is required during optic cup formation to prevent p53-dependent apoptosis and colobomata.

Lee J , Lee BK , Gross JM .

Mutations in BCOR (Bcl6 corepressor) are found in patients with oculo-facio-cardio-dental (OFCD) syndrome, a congenital disorder affecting visual system development, and loss-of-function studies in zebrafish and Xenopus demonstrate a role for Bcor during normal optic cup development in preventing colobomata. The mechanism whereby BCOR functions during eye development to prevent colobomata is not known, but in other contexts it serves as a transcriptional corepressor that potentiates transcriptional repression by B cell leukemia/lymphoma 6 (BCL6). Here, we have explored the function of the zebrafish ortholog of Bcl6, Bcl6a, during eye development, and our results demonstrate that Bcl6a, like Bcor, is required to prevent colobomata during optic cup formation. Our data demonstrate that Bcl6a acts downstream of Vax1 and Vax2, known regulators of ventral optic cup formation and choroid fissure closure, and that bcl6a is a direct target of Vax2. Together, this regulatory network functions to repress p53 expression and thereby suppress apoptosis in the developing optic cup. Furthermore, our data demonstrate that Bcl6a functions cooperatively with Bcor, Rnf2 and Hdac1 in a common gene regulatory network that acts to repress p53 and prevent colobomata. Together, these data support a model in which p53-dependent apoptosis needs to be tightly regulated for normal optic cup formation and that Bcl6a, Bcor, Rnf2 and Hdac1 activities mediate this regulation.

PubMed ID: 23669349
PMC ID: PMC3736873
Article link: Hum Mol Genet
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: bcl6 bcor hdac1 rnf2 tp53 vax1 vax2
GO keywords: eye development [+]

Disease Ontology terms: microphthalmia [+]
References [+] :
Albagli-Curiel, Ambivalent role of BCL6 in cell survival and transformation. 2003, Pubmed