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Mariana Rius, Sunit Dutta, Brian Brooks; Prohibitin is essential in zebrafish optic fissure closure. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4466.
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Uveal coloboma is a potentially blinding ocular malformation that significantly contributes to childhood blindness. It is caused by the failure of optic fissure closure during eye morphogenesis. Optic fissure closure is a highly conserved and complex biological process, yet the governing molecular mechanisms and coloboma formation remain elusive. We previously used developmental profiling to identify a zinc-finger-containing gene, nlz1, as an important regulator of optic fissure closure. NLZ1 was independently shown to interact with prohibitin (PHB/phb), another gene suggested by our developmental screen. phb is thought to regulate cell cycle progression and mitochondrial biogenesis. This study evaluates phb as a candidate gene for coloboma using a zebrafish model.
Whole mount in situ hybridization and RT PCR determined prohibitin expression patterns across relevant developmental stages. Antisense morpholino and RNA rescue measured the loss-of-function effects and confirmed the specificity of the reaction. The resulting phenotype was verified at the cellular level using histological sectioning.
Whole mount in situ hybridization confirmed phb1 and phb2 expression in the eye at 24 hours post fertilization (hpf), 26 hpf, 48 hpf, 72 hpf, and 120 hpf. RT PCR indicated maternal and zygotic expression of phb1 and phb2, and morpholino knockdown revealed a uveal coloboma phenotype. The morphant phenotype was rescued through co-injection with phb1 RNA, verifying the specificity of phb1 in the closure of the optic fissure. Histological analysis confirmed failure of optic fissure closure throughout embryonic development in the morphant embryos.
Loss of prohibitin function results in coloboma in the zebrafish. The identification of a novel gene’s involvement in the fusion of the optic fissure provides insight into the various participants that may contribute to this complex, conserved, and poorly understood mechanism.
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