In this manuscript, we took advantage of <i>Xenopus laevis</i> models of both sexes expressing wild-type human rhodopsin or its class I Q344ter mutant fused to Dendra2 fluorescent protein to characterize a novel light-independent mechanism of photoreceptor degeneration caused by mislocalized rhodopsin.
C57BL/6J mice heterozygous for the mutation in I307Nrhodopsin (<i>Rho</i>) (also known as RHO<sup>Tvrm4/+</sup>, or Tvrm4) are normal until exposed to brief but bright light, whereupon rod photoreceptor degeneration ensues.
Human iPSC-retinas were transplanted in rhodopsin mutant SD-Foxn1 Tg(S334ter)3LavRrrc nude rats and two monkeys with laser-induced photoreceptor degeneration.
P23H is the most common mutation in the RHODOPSIN (RHO) gene leading to a dominant form of retinitis pigmentosa (RP), a rod photoreceptor degeneration that invariably causes vision loss.
Activation of signaling genes and proteins, as well as the dependency on bleachable rhodopsin resembles mechanisms of light-induced photoreceptor degeneration.
Our results demonstrate a previously unknown function of the rhodopsin cytoplasmic domain during opsin-triggered photoreceptor degeneration and may open up new avenues for managing this disease.
This study aimed to differentiate hMSCs into photoreceptor cells by stimulation with growth and differentiation factors in vitro to upregulate gene and protein expression of CRX, NR2E3, and rhodopsin and various phototransduction markers associated with rod photoreceptor development and function and to examine the effect of subretinal transplantation of these cells into the P23H rat, a model of primary photoreceptor degeneration.
We have previously demonstrated that BiP mRNA levels are selectively reduced in animal models of ADRP arising from P23Hrhodopsin expression at ages that precede photoreceptor degeneration.
Thus, the rod photoreceptor degeneration produced in Xenopus laevis by the P23H mutation in an otherwise untagged Xenopus laevis rhodopsin is generally similar to that seen with mammalian rhodopsins and epitope-tagged versions of Xenopus laevis rhodopsin, though some differences remain to be explained.
We show that expression of P23H, but not wild-type rhodopsin, results in a generalized impairment of the ubiquitin proteasome system, suggesting a mechanism for photoreceptor degeneration that links RP to a broad class of neurodegenerative diseases.
In this study, we used transgenic mice with increased expression of FGF2 in photoreceptors (rhodopsin promoter/FGF2 transgenics) to investigate the effects of sustained increased expression of FGF2 in mice with various types of photoreceptor degeneration, including rd mice that are homozygous for mutated phosphodiesterase beta subunit, Q344ter mice that undergo photoreceptor degeneration because of expression of mutated rhodopsin, and mice exposed to 75% oxygen for 1 or 2 weeks.
Thus, we constructed AAV vectors with overlapping CEP290 regions and evaluated their impact on photoreceptor degeneration in Cep290<sup>rd16/rd16</sup> and Cep290<sup>rd16/rd16</sup>;Nrl<sup>-/-</sup> mice, two models of CEP290-LCA.
Additional loss of Bbs4 alleles in Cep290(rd16/rd16) mice results in increased body weight and accelerated photoreceptor degeneration compared with mice without Bbs4 mutations.
Mutations of the centrosomal protein 290 kDa (CEP290) lead to distinct clinical manifestations, including Leber congenital amaurosis (LCA), a hereditary cause of blindness due to photoreceptor degeneration.
Our findings suggest a critical function for CEP290 in ciliary transport and provide insights into the mechanism of early-onset photoreceptor degeneration.