Biology subjects

Coward, R. J.

Publications and source records attributed to Coward, R. J..

3 recordsLinked to original sources

bioRxiv2024

A Novel Role of Hyaluronan and its Membrane Receptors, CD44 and RHAMM in Obesity-Related Glomerulopathy

Obesity-related glomerulopathy (ORG) contributes to diabetic nephropathy and kidney cancer, leading to chronic/end-stage kidney disease. To date, treatments for ORG are limited because of incomplete understanding of the disease pathogenesis. Here, we identified a novel role for hyaluronan (HA) and its membrane receptors, CD44 and RHAMM in obesity-associated renal inflammation, fibrosis, tubular injury, and kidney dysfunction. Pharmacological and genetic ablation of HA, CD44 or RHAMM reversed these renal disorders induced by high fat diet feeding in mice in vivo. Increased HA content, and CD44 and RHAMM expression damaged the kidney via activation of TGF-{beta}1/Smad2/3, P38/JNK MAPK and ROCK/ERK pathways. We further established a link between renal insulin resistance and ECM remodelling using human kidney cells in vitro, shedding mechanistic insight into the role of HA, CD44 and RHAMM in the pathogenesis of ORG. Furthermore, in human kidney biopsies gene expression of CD44 and RHAMM was increased in chronic kidney disease and diabetic nephropathy, and their levels were correlated with markers of kidney (dys)function (GFR, serum creatinine, proteinuria). Our findings provide evidence for HA-CD44/RHAMM as a potential therapeutic target in ORG and consequent prevention of chronic kidney disease.

physiology↗

bioRxiv2024

The insulin / IGF axis is critically important controlling gene transcription in the podocyte.

Signalling to the podocyte via the structurally related insulin receptor (IR) or insulin-like growth factor 1 receptor (IGF1R) is important for podocyte function. This study sought to elucidate the compound role of the insulin/IGF1 axis in podocytes using transgenic mice and cell culture models deficient in both receptors. Podocyte specific IR/IGF1R knockdown mice developed a severe kidney phenotype with albuminuria, glomerulosclerosis and renal failure with death occurring in some mice between 4 and 24 weeks. Simultaneous knockdown of both receptors in cultured podocytes resulted in >50% cell death by 7 days. Proteomic analysis revealed a striking downregulation of spliceosome-related proteins in IR/IGF1R knockdown podocytes with long-read RNA sequence data indicating an increased fraction of transcripts with intron retention/premature termination codons in these cells. Furthermore, phospho-proteomic analysis revealed multiple insulin / IGF1 induced spliceosomal post-translational protein and kinase modifications suggesting dynamic control of this system. This study underlines the importance of podocyte insulin/IGF signalling demonstrating a novel role for this extrinsic hormonal signalling axis in regulating gene transcription in this cell type.

cell biology↗

bioRxiv2021

Extracellular RNA moves from the glomerulus to the renal tubule

There is a wealth of indirect evidence that extracellular RNA (exRNA) signalling can regulate renal tubular epithelial cell function. However, the physiological importance of this signalling is uncertain. We sought to determine the extent of extracellular RNA transfer between cells in a healthy kidney. We tested the hypothesis that RNA travels from glomerular podocytes to renal tubular epithelial cells. We developed a method to track exRNA in the kidney using SLAMseq (SH-linked alkylation for the metabolic sequencing of RNA in tissue). We crossed podocin-Cre mice with floxed-stop-UPRT mice to express recombinant uracil phosphoribosyl transferase (UPRT) in podocytes. Mice were injected with the modified nucleobase 4-thiouracil, which is incorporated into nascent RNA with high efficiency only in UPRT-expressing cells. We harvested glomeruli or tubular cells, extracted RNA and prepared libraries for SLAMseq, in which sites of mRNA labelling with 4-thiouracil are detected as T>C conversions in 3UTRs. In glomeruli, we detected labelling of known podocyte genes but not of genes known to be restricted to endothelial, renal tubular or white blood cells. Setting a false-discovery rate of 1%, the proportion of genes deemed to be labelled with high confidence was 7.1% (95% confidence interval 6.8 - 7.4%) in 4TU-treated podocyte-UPRT mice, 2.5% (2.3 - 2.7%) in Cre-negative controls and 1.0% (0.9 - 1.1%) in 4TU-naive controls. In tubular cells, we detected a small but statistically significant increase in RNA labelling in podocyte-UPRT mice compared to Cre-negative controls (p = 7.4 x 10-16 in a zero-inflated Poisson regression model). We conclude that RNA is transferred from podocytes to renal tubular epithelial cells in vivo under physiological conditions. Our model provides the opportunity to explore the consequences of this novel signalling pathway in health and kidney disease.

molecular biology↗