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K. Boesze-Battaglia, M. Damek-Poprawa, C. Gretzula, D. Pandy, T. Edrington, V; The Role of Peripherin/rds Structural Disorder in the Establishment and Maintenance of Photoreceptor Outer Segments. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2999.
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© ARVO (1962-2015); The Authors (2016-present)
Pathogenic mechanism(s) underlying peripherin/rds (p/rds) mediated retinal dystrophies are unknown, however new insight was gained in our understanding of p/rds function based upon recent structural studies identifying the C-terminal domain of this protein as homologous to structures called intrinsically disordered domains (IDD). IDDs are random structures which are stabilized by interacting with one or with several binding partners. In these studies we develop several in vivo mouse models to determine the role of this domain in the establishment and maintenance of OS structure. We have specifically targeted two functional regions of the p/rds C-terminus, the membrane induced amphiphilic α-helix and the terminal ten residues.
cDNAs encoding wild-type mouse p/rds and two p/rds mutants, RdsF319Y/ V323E and RdsΔ10, were cloned into the pCAGIG plasmid for transfection into developing photoreceptor cells by in vivo electroporation. The RdsF319Y/ V323E mutation alters the amphiphilic helical domain and the Δ10 deletion mutant, RdsΔ10, disrupts melanoregulin binding.The distribution profile of the expressed mutant p/rds was analyzed by laser scanning confocal microscopy. In a complimentary series of studies we used mouse lines expressing rds transgenes, RdsF319Y/ V323E and RdsΔ10, and determined whether photoreceptor structure (assessed by light and electron microscopy) and function (assessed by ERG) were correlated with modifications of the p/rds C-terminus.
We demonstrate successful sub-retinal injection and in vivo electroporation of recombinant p/rds into mouse photoreceptor cells. FLAG-tagged p/rds was expressed in EGFP positive cells in a region consistent with their localization to photoreceptor OSs. The expression of FLAG-rds did not alter gross OS morphology as indicted in EGFP positive sections stained with anti-opsin. In the RdsF319Y/ V323E transgenic, expression of RdsF319Y/ V323E in rds-/- mice resulted in the accumulation of vesicular structures in OS region, suggesting preliminarily that this mutant may traffic properly but results in aberrant OS formation. In the RdsΔ10FLAG transgenic, expression of RdsΔ10FLAG in rds-/- appears to partially rescue these phenotype with formation of disorganized OS.
We propose that the IDD p/rds C-terminal domain plays a direct role in the biogenesis of outer segments (OSs) and in stabilizing OS structure through its interaction with specific cognate binding partners.
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