Molecular mechanisms regulating ocular apoptosis in zebrafish gdf6a mutants.

Purpose: To characterize the molecular mechanisms underlying retinal apoptosis induced by loss of Gdf6, a TGFβ ligand.

Methods: The role of Gdf6 in regulating apoptosis was studied using a zebrafish gdf6a(-/-) mutant, which encodes a truncated, nonfunctional protein. To investigate whether intrinsic or extrinsic apoptotic mechanisms were involved, morpholino antisense oligonucleotides targeting baxa, baxb, and p53 were employed.

Evaluating the mutagenic activity of targeted endonucleases containing a Sharkey FokI cleavage domain variant in zebrafish.

Synthetic targeted endonucleases such as zinc finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs) have recently emerged as powerful tools for targeted mutagenesis, especially in organisms that are not amenable to embryonic stem cell manipulation. Both ZFNs and TALENs consist of DNA-binding arrays that are fused to the nonspecific FokI nuclease domain. In an effort to improve targeted endonuclease mutagenesis efficiency, we enhanced their catalytic activity using the Sharkey FokI nuclease domain variant.

Apoptotic and proliferative defects characterize ocular development in a microphthalmic BMP model.

Purpose: Vision is critically dependent on ocular size, which is regulated by environmental and genetic factors. Mutation of human Growth and Differentiation Factor 6 (GDF6) or zebrafish gdf6a results in a spectrum of small eye phenotypes (microphthalmia, anophthalmia, and coloboma). However, current models do not explain their etiology fully.

Hmx4 regulates Sonic hedgehog signaling through control of retinoic acid synthesis during forebrain patterning.

Mutations in H6-homeobox (HMX) genes are linked to neural mispatterning and neural tube closure defects in humans. We demonstrate that zebrafish Hmx4 regulates the signaling of two morphogens critical for neural development, retinoic acid (RA) and Sonic hedgehog (Shh). Hmx4-depleted embryos have a strongly narrowed eye field and reduced forebrain Shh target gene expression.