Project description:Freshly isolated rat kidney medullary thick ascending limbs were subjected for transcript profiling. Three microarray experiments were done to obtain the kidney medullary thick ascending limb transcriptome.
Project description:We created a rat renal congestion model and investigated the effect of renal congestion on hemodynamics and molecular mechanisms. The inferior vena cava (IVC) between the renal veins was ligated by suture in male Sprague-Dawley rats to increase upstream IVC pressure and induce congestion in the left kidney only. Left kidney congestion reduced renal blood flow, glomerular filtration rate, and increased renal interstitial hydrostatic pressure. Tubulointerstitial and glomerular injury and medullary thick ascending limb hypoxia were observed only in the congestive kidneys. Molecules related to extracellular matrix expansion, tubular injury, and focal adhesion were upregulated in microarray analysis. Renal decapsulation ameliorated the tubulointerstitial injury. Electron microscopy captured pericyte detachment in the congestive kidneys. Transgelin and platelet-derived growth factor receptors, as indicators of pericyte-myofibroblast transition, were upregulated in the pericytes and the adjacent interstitium. With the compression of the peritubular capillaries and tubules, hypoxia and physical stress induce pericyte detachment, which could result in extracellular matrix expansion and tubular injury in renal congestion.
Project description:The mechanism driving the remarkable ability of the remaining kidney to enlarge and increase its function following the removal of its contralateral pair remains elusive. To explore the pathways driving compensatory renal hypertrophy, comprehensive RNA-seq transcriptional studies were undertaken in the kidneys of C57BL/6 mice undergoing hypertrophy at 24, 48, and 72 hours following nephrectomy, and these results were compared with mice undergoing sham operations. In addition, mass spectrometry was carried out at 24 hours to examine changes in protein expression. Single-nuclei RNA-Seq was used to delineate bulk RNA-seq data into cell types at 24 hours post-nephrectomy. HK-2 renal tubular cells were examined for their ability to undergo hypertrophy in the presence of IGF-1 via the activation of cholesterol biosynthesis pathways. Bulk RNA-seq revealed substantial time-dependent enhancement of cholesterol biosynthesis pathways, increases in mitochondrial gene expression, and cell cycle perturbations. Single-nuclei RNA-Seq at 24 hours post-nephrectomy showed that Sterol Binding Protein 2 (SREBP2) activity increases in medullary thick ascending limb cells and, to a lesser extent, in proximal tubular cells, consistent with the role of promoting cholesterol synthesis. Furthermore, SREBP2 was found to regulate cell size following IGF-1 stimulation in HK-2 cells. There are early, cell-specific alterations in gene expression of cholesterol biosynthesis pathways, mitochondrial genes, and the cell cycle in kidneys undergoing compensatory hypertrophy. SREBP2 activity in the medullary thick ascending limb and, to a lesser extent, in proximal tubules may play a previously undescribed role in promoting cholesterol metabolism in the mechanism underlying compensatory renal hypertrophy.
Project description:Uromodulin is the most abundant urinary protein. It is exclusively produced and released in the urine by renal epithelial cells lining the thick ascending limb of Henle’s loop (TAL). Mutations in UMOD, the gene encoding uromodulin, cause autosomal dominant tubulointerstitial kidney disease uromodulin-related (ADTKD-UMOD). While the primary effect of all mutations, retention in the endoplasmic reticulum (ER), is well established, its downstream effects are still unknown. The aim of this study was to gain insight into ADTKD-UMOD pathogenesis through transcriptional profiling of immortalised mouse TAL cells (mTAL) transduced with lentiviral vectors encoding wild type or mutant (C150S) GFP-tagged human uromodulin.
Project description:Uromodulin (UMOD) is a secreted glycoprotein exclusively expressed by the cells lining the thick ascending limb of the loop of henle and the early distal tubule of the kidney nephron. Mutations in UMOD that interfere with proper folding of the protein are responsible for a progressive form of interstitial fibrotic kidney disease that leads to end stage renal disease, referred to as Uromodulin Associated Kidney Disease (UAKD). To assess key transcriptional changes associated with the progression of UAKD, we generated a knock-in mouse model harboring the mouse equivalent of the human mutation C148W. We profiled both the whole kidney tissue, as well as the specific UMOD+ cell populaitons in mutant and wild type mice. Analysis of differentially expressed genes in whole tissue and UMOD+ cells revealed a strong TNF-signaling signature, as well as TRIB3 upregulation, which is a key mediator of the intrinsic ER-stress mediated cell death pathway.
Project description:The mechanisms of chronic kidney disease-associated secondary hyperparathyroidism are partially understood. In this project we aimed to gain new information and propose research hypotheses by proteome and phosphoproteome profiling of normal and hyperplastic rat parathyroid glands. Glands were microdissected from rats on normal control diet or CKD-inducing high adenine diet enriched with phosphorus to produce secondary hyperparathyroidism. Protein extracts were pooled from 4 glands (2 rats) for proteome profiling (3 normal and 3 CKD pools), and from 12 glands (6 rats) for phosphoproteome profiling (2 normal and 2 CKD pools).