Gene expression changes during cataract progression in Sparc null mice: differential regulation of mouse globins in the lens.
OBJECTIVE
Sparc/osteonectin is a hydroxyapatite, calcium and, collagen binding protein, implicated in tissue morphogenesis, cell proliferation, and repair. Sparc null mice develop sub-cortical posterior cataract with eventual rupture of the lens. We wished to correlate genotype with phenotype in these mice via analysis of gene expression pattern changes leading to disease.


METHODS
We carried out microarray analysis of adult lenses from Sparctm1cam knockout mice on two strain backgrounds of varying phenotypic severity at two time points, 4 and 9 months. Labelled cDNA from Sparctm1cam knockout and age, strain, and sex matched control lenses was hybridized with HGMP NIA 15,000 clone set arrays. Differential expression was confirmed using semi-quantitative RT-PCR.


RESULTS
We have confirmed differential expression of 54 genes. Most notably, 5 of the mouse globin genes, Hbb-b1, Hbb-b2, Hba, Hba-x, and Hbb-y and an EST, C79876, were significantly downregulated in 9-month old Sparc null mice from two genetic backgrounds at different stages of disease. Another downregulated gene, EraF, is involved in folding of globin proteins. Immune response components, including various members of the complement cascade, were upregulated in lenses with advanced cataract.


CONCLUSIONS
Five mouse globins show persistent downregulation as a result of Sparc loss. We speculate as to possible roles of this phenomenon on pathogenesis of cataract in these mice. Other confirmed genes allow extension of previous models of cataract development in Sparc null mice.
Mansergh
Fiona C
FC
School of Biosciences, Cardiff University, Cardiff, Wales, UK.
Wride
Michael A
MA
Walker
Veronica E
VE
Adams
Steffan
S
Hunter
Susan M
SM
Evans
Martin J
MJ
D000818:Animals; D002386:Cataract / Q000235:genetics* / Q000473:pathology; D017931:DNA Primers / Q000737:chemistry; D018450:Disease Progression; D015536:Down-Regulation; D020224:Expressed Sequence Tags; D017353:Gene Deletion; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000502:physiology*; D005838:Genotype; D005914:Globins / Q000235:genetics*; D007908:Lens, Crystalline / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D020411:Oligonucleotide Array Sequence Analysis; D015676:Osteonectin / Q000172:deficiency / Q000502:physiology*; D010641:Phenotype; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D017931:DNA Primers; D015676:Osteonectin; D012333:RNA, Messenger; D005914:Globins