Analysis of chronic kidney disease patients by targeted next-generation sequencing identifies novel variants in kidney-related genes

Dent disease 1-linked novel CLCN5 mutations result in aberrant location and reduced ion currents

Dent disease is a rare renal tubular disease with X-linked recessive inheritance characterized by low molecular weight proteinuria (LMWP), hypercalciuria, and nephrocalcinosis. Mutations disrupting the 2Cl-/1H+ exchange activity of chloride voltage-gated channel 5 (CLCN5) have been causally linked to the most common form, Dent disease 1 (DD1), although the pathophysiological mechanisms remain unclear. Here, we conducted the whole exome capture sequencing and bioinformatics analysis within our DD1 cohort to identify two novel causal mutations in CLCN5 (c.749 G > A, p. G250D, c.829 A > C, p. T277P). Molecular dynamics simulations of ClC-5 homology model suggested that these mutations potentially may induce structural changes, destabilizing ClC-5. Overexpression of variants in vitro revealed aberrant subcellular localization in the endoplasmic reticulum (ER), significant accumulation of insoluble aggregates, and disrupted ion transport function in voltage clamp recordings. Moreover, human kidney-2 (HK-2) cells overexpressing either G250D or T277P displayed higher cell-substrate adhesion, migration capability but reduced endocytic function, as well as substantially altered transcriptomic profiles with G250D resulting in stronger deleterious effects. These cumulative findings supported pathogenic role of these ClC-5 mutations in DD1 and suggested a cellular mechanism for disrupted renal function in Dent disease patients, as well as a potential target for diagnostic biomarker or therapeutic strategy development.

Identification of hub genes and their correlation with immune infiltrating cells in membranous nephropathy: an integrated bioinformatics analysis

BACKGROUND

Membranous nephropathy (MN) is a chronic glomerular disease that leads to nephrotic syndrome in adults. The aim of this study was to identify novel biomarkers and immune-related mechanisms in the progression of MN through an integrated bioinformatics approach.

METHODS

The microarray data were downloaded from the Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) between MN and normal samples were identified and analyzed by the Gene Ontology analysis, the Kyoto Encyclopedia of Genes and Genomes analysis and the Gene Set Enrichment Analysis (GSEA) enrichment. Hub The hub genes were screened and identified by the weighted gene co-expression network analysis (WGCNA) and the least absolute shrinkage and selection operator (LASSO) algorithm. The receiver operating characteristic (ROC) curves evaluated the diagnostic value of hub genes. The single-sample GSEA analyzed the infiltration degree of several immune cells and their correlation with the hub genes.

RESULTS

We identified a total of 574 DEGs. The enrichment analysis showed that metabolic and immune-related functions and pathways were significantly enriched. Four co-expression modules were obtained using WGCNA. The candidate signature genes were intersected with DEGs and then subjected to the LASSO analysis, obtaining a total of 6 hub genes. The ROC curves indicated that the hub genes were associated with a high diagnostic value. The CD4+ T cells, CD8+ T cells and B cells significantly infiltrated in MN samples and correlated with the hub genes.

CONCLUSIONS

We identified six hub genes (ZYX, CD151, N4BP2L2-IT2, TAPBP, FRAS1 and SCARNA9) as novel biomarkers for MN, providing potential targets for the diagnosis and treatment.