Abstract
Purpose :
Mutations in αB-crystallin have been implicated in autosomal cataracts and myopathy in humans. These mutations have been shown to compromise the chaperone activity of αB-crystallin in vitro but its exact roles in maintenance of the lens transparency or muscular structure/function in vivo remains unclear. The transparency of embryos and the amenability for genetic manipulations make zebrafish ideally suited to study developmental processes or disease progression. We have established mutant zebrafish lines by targeted genome editing that disrupt both paralogs of αB-crystallin gene, cryaba and cryabb. The embryos from the presumptive null alleles of cryaba (cryaba-/-) and cryabb (cryabb-/-) were screened for lens defects and phenotypes in muscle tissues.
Methods :
Zebrafish larvae (3-5 dpf) treated with 1-phenyl 2-thiourea (PTU) were examined by bright field (BF) and differential interference contrast (DIC) microscopy for screening the lens phenotypes. Histology and immunostaining were performed to analyze muscular phenotypes.
Results :
The adult cryaba and cryabb mutant founders generated by CRISPR/Cas9 system were screened for germ-line transmission of insertions and deletions (INDELS) and confirmed by sequencing. The presumptive null alleles were propagated to subsequent generations to raise stable lines. Apparent lens defects were observed in the cryaba-/- and cryabb-/- embryos. A proportion of cryaba-/- and cryabb-/- embryos developed pericardial edema and showed heart phenotypes resembling dilated cardiomyopathy when stress challenged.
Conclusions :
Our preliminary results suggested that αB-crystallin plays an important role in embryonic lens development in zebrafish and is potentially involved in the cellular responses that protect cardiac muscles under stress conditions. Detailed molecular analyses on the observed lens defects and the cardiac phenotypes are currently in progress. We believe that zebrafish can be used as a model to study chaperonopathies and to discover novel therapeutics against proteostatic diseases.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.