Purchase this article with an account.
Suraj P Bhat, Rajendra K Gangalum, Zhe Jing; A DNA Binding Domain Mutation in HSF4 Found in Age- Related Cataract Patients and in Normal Populations Causes Lamellar Cataract in Transgenic Mice. Invest. Ophthalmol. Vis. Sci. 2014;55(13):5039.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The most prevalent form of early childhood cataract is associated with dominant mutations in the DNA binding domain of the heat shock transcription Factor4 (HSF4). We have shown that disruption of the DNA binding domain (DBD) of the HSF4 gene recapitulates the dominant human lamellar cataract in mice. Population studies have indicated that a mutation in the exon 3 (R116H) in HSF4 DBD is associated with age-related cataracts. However, this mutation was also found in 3% of the normal population suggesting incomplete penetrance. Since an interference with the DNA binding domain functions of HSF4 lead to dominant phenotypes of Lamellar Cataract formation in humans and in transgenic mice, we wanted to ascertain the phenotype if any, associated with this mutation.
We used Red E/T based counter selection system and ‘recombineering’ to modify the large BAC (Bacterial artificial chromosome) DNA molecules to introduce a single base mutation into the exon3 (part of the DNA binding Domain) of the HSF4 gene. Use of BACs for transgenesis allows expression of the transgene that is similar to in vivo patterns of expression. The manipulated HSF4 transgene would produce a mutant HSF4 with DBD containing the human R116H mutation in the developing ocular lens of the transgenic mouse, in a temporally and spatially correct manner.
Slit lamp examinations of the founders and F1 and F2 generations of animals revealed nuclear opacities similar to the human lamellar cataract phenotypes. This phenotype of dots and/or streaks is confined to a few lamellae or fiber cells within the nucleus of the lens (see Fig 1). Further characterization revealed abnormalities in the secondary fiber cell differentiation attended by varied effects on the expression of a number of genes including the crystallins.
The cataract recapitulated in the transgenic mice shows characteristic lamellar cataract phenotype both at the morphological as well as at the molecular level. These data suggest that the individuals catalogued under ‘normal population’ carrying the R116H substitution may have escaped clinical examination of the incipient lamellar cataract phenotype. This data will be discussed in light of the complete and incomplete penetrance of cataract phenotypes.
This PDF is available to Subscribers Only