VCANCanonical Splice Site Mutation is Associated With Vitreoretinal Degeneration and Disrupts an MMP Proteolytic Site

Abstract

PurposeTo gain insight into the pathophysiology of vitreoretinal degeneration, the clinical course of three family members with Versican Vitreoretinopathy (VVR) is described, and a canonical splice site mutation in the gene encoding for versican (VCAN) protein was biochemically analyzed.MethodsA retrospective chart review, human eye histopathology, Sanger DNA sequencing, protein structural modeling, and in vitro proteolysis assays were performed.ResultsThe proband (II:1), mother (I:2), and younger sibling (II:2) suffered retinal degeneration with foveal sparing and retinal detachments with proliferative vitreoretinopathy, features that were confirmed on histopathologic analysis. All affected members carried a heterozygous adenine to guanine variant (c.4004-2A>G) predicted to result in exon 8 skipping or the deletion of 13 amino acids at the beginning of the GAGβ chain (VCAN p.1335-1347). This deleted region corresponded to a putative MMP cleavage site, validated using fluorescence resonance energy transfer (FRET)-based proteolysis assays. Proteomic network analysis identified 10 interacting partners in the human vitreous and retina linked to retinal detachment and degeneration.ConclusionsVVR causes significant ocular disease, including retinal detachment and retinal dystrophy. The intronic VCAN mutation removes an MMP cleavage site, which alters versican structure and results in abnormal vitreous modeling. Disruption of a versican protein network may underlie clinicopathologic disease features and point to targeted therapies.

Identification of Novel Copy Number Variations of VCAN Gene in Three Chinese Families with Wagner Disease

“…In order to check if the VCAN deletion resulted in an imbalanced expression of VCAN transcript isoforms ( Supplementary Figure S3 ), real-time PCR assays were carried out from the three kindreds. In kindred A, one exon–intron junction of exon 8 was removed, while the whole of exon 8 and at least part of exon 9 were deleted in kindred B and kindred C. As shown in Figure 4 , the four isoforms of versican transcripts showed a substantial increase in the quantitative ratio of V2 and V3 isoforms (both p < 0.0001), with a decrease in the quantitative ratio of V0 and V1 isoforms (both p = 0.0003) in kindred A, consistent with previously reported studies [ 3 , 8 , 12 , 14 ]. In the other two kindreds, the VCAN deletion involved exon 9, as well as exon 8, which played a role in the transcription of isoforms V2 and V3.…”

“…The disease-causing molecular defect for WD is a mutation of the VCAN/versican gene [ 3 , 8 ]. This gene is located on chromosome 5q13-q14 and consists of 15 exons which encode chondroitin sulfate proteoglycan 2 (CSPG2/versican).…”

ROP18-Mediated Transcriptional Reprogramming of HEK293T Cell Reveals New Roles of ROP18 in the Interplay Between Toxoplasma gondii and the Host Cell

“…Additionally, SLC38A8 contributes to congenital nystagmus (Weiner et al, 2020), and RIMS1 and CABP4 are associated with dystrophy (Sisodiya et al, 2007) and synaptic disorder of cone-rod (Littink et al, 2009), respectively. Furthermore, alteration of CRYAB is associated with cataract (Molnar et al, 2019), and VCAN is associated with vitreoretinal degeneration (Tang et al, 2019). Most of these eye disease-related genes were upregulated in HEK293T cells by ROP18 ( Supplementary Table S3).…”

Proteomic insight into the pathogenesis of CAPN5-vitreoretinopathy

“…Versican is a chondroitin sulfate proteoglycan involved in maintaining the physiologic structure of the vitreous. Interestingly, loss of versican expression and function is implicated in vitreoretinal degeneration (versican vitreoretinopathy; OMIM: 118661) 28 . A comparative analysis revealed 49 upregulated proteins and 74 downregulated proteins were shared among the three stages, suggesting that different stages of CAPN5-NIV may share similar pathways and classifications of proteins (Fig.…”