Chronic kidney disease (CKD) is a risk factor for cardiovascular disease (CVD), partly due to phosphate-induced vascular calcification. Fetuin-A stabilizes calcium-phosphate complexes into calciprotei Show more
Chronic kidney disease (CKD) is a risk factor for cardiovascular disease (CVD), partly due to phosphate-induced vascular calcification. Fetuin-A stabilizes calcium-phosphate complexes into calciprotein particles (CPPs), preventing precipitation, but CPPs can mature into crystalline particles that drive calcification, particularly in CKD. In this study, we investigated whether citrate, a calcium chelator, could mitigate CPP-induced vascular calcification in vitro. Vascular smooth muscle cells (VSMCs) were incubated with CPPs containing varying citrate concentrations. We quantified calcification using calcium assays and characterized CPPs using spectrophotometry, dynamic light scattering, cryogenic transmission electron microscopy (cryo-TEM), electron diffraction (ED), Raman spectroscopy, energy dispersive X-ray spectroscopy, and mass spectrometry (MS). The highest citrate concentration, reduced calcification by 88% versus standard CPPs ( Show less
Steroid-resistant nephrotic syndrome (SRNS) almost invariably progresses to end-stage renal disease. Although more than 50 monogenic causes of SRNS have been described, a large proportion of SRNS rema Show more
Steroid-resistant nephrotic syndrome (SRNS) almost invariably progresses to end-stage renal disease. Although more than 50 monogenic causes of SRNS have been described, a large proportion of SRNS remains unexplained. Recently, it was discovered that mutations of NUP93 and NUP205, encoding 2 proteins of the inner ring subunit of the nuclear pore complex (NPC), cause SRNS. Here, we describe mutations in genes encoding 4 components of the outer rings of the NPC, namely NUP107, NUP85, NUP133, and NUP160, in 13 families with SRNS. Using coimmunoprecipitation experiments, we showed that certain pathogenic alleles weakened the interaction between neighboring NPC subunits. We demonstrated that morpholino knockdown of nup107, nup85, or nup133 in Xenopus disrupted glomerulogenesis. Re-expression of WT mRNA, but not of mRNA reflecting mutations from SRNS patients, mitigated this phenotype. We furthermore found that CRISPR/Cas9 knockout of NUP107, NUP85, or NUP133 in podocytes activated Cdc42, an important effector of SRNS pathogenesis. CRISPR/Cas9 knockout of nup107 or nup85 in zebrafish caused developmental anomalies and early lethality. In contrast, an in-frame mutation of nup107 did not affect survival, thus mimicking the allelic effects seen in humans. In conclusion, we discovered here that mutations in 4 genes encoding components of the outer ring subunits of the NPC cause SRNS and thereby provide further evidence that specific hypomorphic mutations in these essential genes cause a distinct, organ-specific phenotype. Show less