Cwc27, associated with retinal degeneration, functions as a splicing factorin vivo

Abstract

Previous in vitro studies indicate that CWC27 functions as a splicing factor in the Bact spliceosome complex, interacting with CWC22 to form a landing platform for eIF4A3, a core component of the exon junction complex. However, the function of CWC27 as a splicing factor has not been validated in any in vivo systems. CWC27 variants have been shown to cause autosomal recessive retinal degeneration, in both syndromic and non-syndromic forms. The Cwc27K338fs/K338fs mouse model was shown to have significant retinal dysfunction and degeneration by 6 months of age. In this report, we have taken advantage of the Cwc27K338fs/K338fs mouse model to show that Cwc27 is involved in splicing in vivo in the context of the retina. Bulk RNA and single cell RNA-sequencing of the mouse retina showed that there were gene expression and splicing pattern changes, including alternative splice site usage and intron retention. Positive staining for CHOP suggests that ER stress may be activated in response to the splicing pattern changes and is a likely contributor to the disease mechanism. Our results provide the first evidence that CWC27 functions as a splicing factor in an in vivo context. The splicing defects and gene expression changes observed in the Cwc27K338fs/K338fs mouse retina provide insight to the potential disease mechanisms, paving the way for targeted therapeutic development.

Depletion of Retinal Dopaminergic Activity in a Mouse Model of Rod Dysfunction Exacerbates Experimental Autoimmune Uveoretinitis: A Role for the Gateway Reflex

“…The absence of a normal (full-length) protein expression was also observed for the Gnat1 gene product in the neuroretina of Gnat1 rd17 mice by Western blot analysis ( Figure 3 c and Figure S4a ), which agrees with the Jackson Laboratory specification of the Gnat1 rd17 phenotype [ 30 , 33 ]. The most upregulated gene in the neuroretina of Gnat1 rd17 mice, Cwc20 , was a CWC22 spliceosome-associated protein ( Figure 3 b) that functions as the major partner of CWC27 (CWC27 spliceosome-associated cyclophilin), a splicing factor linked to retinal degeneration and other developmental defects [ 45 , 46 ].…”

“…In addition, we identified Cwc22 as the most upregulated gene in the neuroretina of Gnat1 rd17 mice. The biological importance of CWC22 in the retina is not completely understood, but it interacts with the splicing factor CWC27, involved in retinal dysfunction and degeneration [ 45 , 46 ]. Interestingly, the overexpression of Cwc22 was also observed in sensory neurons of diabetic mice, where it was found to act as a mediator of diabetic polyneuropathy [ 104 ].…”

Susceptibility Loci in SLC15A1, UGT1A3, and CWC27 Genes Associated with Bladder Cancer in the Northeast Chinese Population

“…CWC27 has an N-terminal PPIase domain containing a proline-binding pocket to bind to proline and a large C-terminal repetitive low complexity region of unknown function [ 29 ]. The disruptions of CWC27 can lead to a spectrum of isolation from syndromic phenotypes, including retinal degeneration, brachydactyly, craniofacial abnormalities, short stature, and neurological defects [ 30 , 31 ]. Ma et al [ 32 ] reported that CNVs in CWC27 were related to familial hemangioblastomas.…”

The Musashi proteins are post-transcriptional activators of protein expression and alternative exon splicing in vertebrate photoreceptors

“…Closer examination of the upregulated proteins revealed proteins (GFAP, CLU, STAT3, JUNB, IRF9, A2M, B2M, complement components) that are expressed at elevated levels across various models of retinal degeneration (Bertrand et al, 2021, p. 27, 2021, p. 27; Cheng and Molday, 2013; Hackam et al, 2004; Uren et al, 2014). Single cell RNA-Seq of the Cwc27 fs model of retinal degeneration further indicated that many of the upregulated genes are expressed by glia (Bertrand et al, 2021). To determine how MSI1 and MSI2 regulate protein expression in photoreceptor cells, we defined two sets of genes.…”

“…In contrast to the downregulated proteins, most of the proteins with increased expression in the knockout retina were associated with Gene Ontology terms and KEGG pathways involved in cell proliferation, extracellular matrix structure, immune response, and angiogenesis (Supplementary Table 5). Closer examination of the upregulated proteins revealed proteins (GFAP, CLU, STAT3, JUNB, IRF9, A2M, B2M, complement components) that are expressed at elevated levels across various models of retinal degeneration (Bertrand et al, 2021, p. 27, 2021, p. 27; Cheng and Molday, 2013; Hackam et al, 2004; Uren et al, 2014). Single cell RNA-Seq of the Cwc27 fs model of retinal degeneration further indicated that many of the upregulated genes are expressed by glia (Bertrand et al, 2021).…”