Early manifestations and differential gene expression associated with photoreceptor degeneration in Prominin-1-deficient retina.

Retinitis pigmentosa (RP) and macular dystrophy (MD) are characterized by gradual photoreceptor death in the retina and are often associated with genetic mutations including those in the Prominin-1 (Prom1) gene. Prom1-knockout (KO) mice recapitulate key features of these diseases including light-dependent retinal degeneration and constriction of retinal blood vessels. The mechanisms underlying such degeneration have remained unclear, however. We here analysed early events associated with retinal degeneration in Prom1-KO mice. We found that photoreceptor cell death and glial cell activation occur between 2 and 3 weeks after birth. Whereas gene expression was not affected at 2 weeks, the expression of several genes was altered at 3 weeks in the Prom1-KO retina, with the expression of that for Endothelin-2 (Edn2) being markedly up-regulated. Expression of Edn2 was also induced by light stimulation in Prom1-KO mice reared in the dark. Treatment with endothelin receptor antagonists attenuated photoreceptor cell death, gliosis, and retinal vessel stenosis in Prom1-KO mice. Our findings thus reveal early manifestations of retinal degeneration in a model of RP/MD and suggest potential therapeutic agents for these diseases.