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Hum Mol Genet 2007 Jul 15;1614:1773-82. doi: 10.1093/hmg/ddm125.
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Left-sided embryonic expression of the BCL-6 corepressor, BCOR, is required for vertebrate laterality determination.

Hilton EN , Manson FD , Urquhart JE , Johnston JJ , Slavotinek AM , Hedera P , Stattin EL , Nordgren A , Biesecker LG , Black GC .

Oculofaciocardiodental (OFCD) syndrome is an X-linked male lethal condition encompassing cardiac septal defects, as well as ocular and dental anomalies. The gene mutated in OFCD syndrome, the BCL-6 corepressor (BCOR), is part of a transcriptional repression complex whose transcriptional targets remain largely unknown. We reviewed cases of OFCD syndrome and identified patients exhibiting defective lateralization including dextrocardia, asplenia and intestinal malrotation, suggesting that BCOR is required in normal laterality determination. To study the function of BCOR, we used morpholino oligonucleotides (MOs) to knockdown expression of xtBcor in Xenopus tropicalis, thus creating an animal model for OFCD syndrome. The resulting tadpoles had cardiac and ocular features characteristic of OFCD syndrome. Reversed cardiac orientation and disorganized gut patterning were seen when MOs were injected into the left side of embryos, demonstrating a left-sided requirement for xtBcor in lateral determination in Xenopus. Ocular defects displayed no left-right bias and included anterior and posterior segment disorders such as microphthalmia and coloboma. Expression of xtPitx2c was shown to be downregulated when xtBcor was depleted. This identifies a pathway in which xtBcor is required for lateral specification, a process intrinsically linked to correct cardiac septal development.

PubMed ID: 17517692
Article link: Hum Mol Genet
Grant support: [+]

Species referenced: Xenopus tropicalis
Genes referenced: bcor ccnd2 gapdh gata4 kit nkx2-5 nodal1 pitx2 tp53
Antibodies: Tnnt2 Ab1
Morpholinos: bcor MO1 bcor MO2

Disease Ontology terms: syndromic microphthalmia 2
Phenotypes: Xtr Wt + bcor MO (fig.3.b) [+]

Article Images: [+] show captions