Basement membrane defects in CD151-associated glomerular disease

Abstract

Background CD151 is a cell-surface molecule of the tetraspanin family. Its lateral interaction with laminin-binding integrin ɑ3β1 is important for podocyte adhesion to the glomerular basement membrane (GBM). Deletion of Cd151 in mice induces glomerular dysfunction, with proteinuria and associated focal glomerulosclerosis, disorganisation of GBM and tubular cystic dilation. Despite this, CD151 is not routinely screened for in patients with nephrotic-range proteinuria. We aimed to better understand the relevance of CD151 in human kidney disease. Methods Next-generation sequencing (NGS) was used to detect the variant in CD151. Electron and light microscopy were used to visualise the filtration barrier in the patient kidney biopsy, and immunoreactivity of patient red blood cells to anti-CD151/MER2 antibodies was performed. Further validation of the CD151 variant as disease-causing was performed in zebrafish using CRISPR-Cas9. Results We report a young child with nail dystrophy and persistent urinary tract infections who was incidentally found to have nephrotic-range proteinuria. Through targeted NGS, a novel, homozygous truncating variant was identified in CD151, a gene rarely reported in patients with nephrotic syndrome. Electron microscopy imaging of patient kidney tissue showed thickening of GBM and podocyte effacement. Immunofluorescence of patient kidney tissue demonstrated that CD151 was significantly reduced, and we did not detect immunoreactivity to CD151/MER2 on patient red blood cells. CRISPR-Cas9 depletion of cd151 in zebrafish caused proteinuria, which was rescued by injection of wild-type CD151 mRNA, but not CD151 mRNA containing the variant sequence. Conclusions Our results indicate that a novel variant in CD151 is associated with nephrotic-range proteinuria and microscopic haematuria and provides further evidence for a role of CD151 in glomerular disease. Our work highlights a functional testing pipeline for future analysis of patient genetic variants. Graphical abstract A higher resolution version of the Graphical abstract is available as Supplementary information

A novel nanoluciferase transgenic reporter measures proteinuria in zebrafish

“…Hanks' balanced salt solution is a saline solution that on injection causes water influx into the blood vasculature and has been shown to expand glomerular capillaries. 42 Thus, we hypothesized that the injection of Hanks' balanced salt solution would create an acute mechanical loading in the glomerulus that would cause proteinuria. In support of this, we observed increased clearance of a 500 kDa fluorescein isothiocyanate-conjugated dextran (n ¼ 6, Figure 6a).…”

Epidermolysis Bullosa—A Different Genetic Approach in Correlation with Genetic Heterogeneity

“…Nephropathy manifests with proteinuria and progression to end-stage renal disease [ 7 , 34 , 70 ]. Homozygous frameshift and splice-site mutations in exon 5 of the CD151 gene leading to truncated proteins without an integrin-binding domain, were reported [ 13 , 53 , 70 , 71 ].…”

Mimicking the Natural Basement Membrane for Advanced Tissue Engineering

“… 21 Additionally, defects in genes coding CD151 are associated with defects in the glomerular BM, and defects in the Lmγ1 gene leads to embryonic death associated with nondeveloped BM. 22 , 23 Moreover, defects in BM regeneration or development have also been observed in cases of corneal stromal fibrosis and epidermolysis bullosa. 24 , 25 …”

“…Mutations in genes that code for the collagen IV network including COL4A3, COL4A4, COL4A5 can lead to Alport Syndrome or thin BM nephropathy (TBMN) that affect the kidney filtration barrier . Additionally, defects in genes coding CD151 are associated with defects in the glomerular BM, and defects in the Lmγ1 gene leads to embryonic death associated with nondeveloped BM. , Moreover, defects in BM regeneration or development have also been observed in cases of corneal stromal fibrosis and epidermolysis bullosa. , …”