Abstract
Abstract: :
Purpose: Lens opacity 11 (lop11) is an autosomal recessive mouse cataract locus that arose spontaneously in RIII strain. At weaning, mice exhibit total cataracts with vacuoles. The goal of this study was to map lop11 onto a mouse chromosome and establish mouse/human homology of the lop11 locus region. Methods: The lop11 mice were outcrossed to CAST/Ei and F1 mice were backcrossed to lop11. We generated 195 backcross progeny. At weaning the progeny were evaluated with a slit lamp following mydriasis with 1% tropicamide. After noting the phenotype, the progeny were euthanized and tissues were collected. Genomic DNA was isolated from collected spleens. Microsatellite markers were selected to evenly cover the mouse genome. Genotypes were determined by PCR amplification of genomic DNA. For exon scanning primers were designed about 50 bp away from intron/exon junctions. Results: : Linkage was detected between lop11 locus and microsatellite markers on chromosome 8. No recombinants were detected with D8Mit198, thee recombinants were detected with D8Mit110 and a single recombinant with D8Mit313. Evaluation of a mouse map of the lop11 critical region identified Hsf4 as a candidate gene. In humans, mutations in Hsf4 lead to development of cataracts. Exon scanning of exons 1–9 did not reveal any sequence difference between lop11 and wild type. However, exons 10–13 could not be amplified from lop11 DNA. RT–PCR on mRNA from lop11 with primers specific to Hsf4 exons 1–9 generated a product, but not with primers from exons 10–13. Conclusions: We mapped lop11 to mouse chromosome 8 between D8Mit198 and D8Mit313. The lop11 critical region identified Hsf4 as a candidate gene. Our initial findings suggest that a mutation in Hsf4 might be responsible for cataracts. Currently, we are further analyzing sequence of Hsf4 transcript in lop1 as well as expression of Hsf4 via northern blots. In addition, we are analyzing sequences downstream of Hsf4 in DNA of lop11.
Keywords: cataract • genetics • mutations