Retinal Degeneration in Transgenic Mouse Expressing the N-terminal Domain of RGS9

Abstract

Abstract: : Purpose:To investigate the role of the N-terminal domain of RGS9 in retinal photoreceptors. Methods:RGS9 N-terminal domain was expressed in cultured cells and in adult mouse photoreceptors. Yeast two- hybrid screen were employed to identify proteins that interact with RGS9 N-terminal domain. Terminal-dUTP-Nick-End-Labeling (TUNEL)and Annexin V binding assays were use to detect cells undergoing apoptosis. Results:Transgenic mouse lines expressings the N-terminal domain of RGS9 under the control of a 4.4 Kb mouse opsin promoter (TG9N) were produced in the wild type and in the RGS9 knockout backgrounds. Gross retinal morphology appeared normal at 3 weeks of age, although TUNEL-positive nuclei could be detected in the outer nuclear layer of the TG9N mouse retinas. Degeneration of TG9N retinal photoreceptors was evident at 3 month of age ( ≷ 90% reduction of the outer nuclear layer). Expression of RGS9 N-terminal domain in the HEK293 cells did not lead to cell death. A number of genes were found interacting with the RGS9 N-terminal domain by yeast two hybrid screens. Conclusion:Photorecetpor degeneration caused by the expression of RGS9 N-terminal domain is an unexpected result. RGS9 may thus be involved in apoptosis pathways in photoreceptors through its N-terminal domain. The TG9N mice should be useful to study the mechanism of photoreceptor degeneration in general.

Keywords: 385 degenerations/dystrophies • 517 photoreceptors • 561 retinal degenerations: cell biology