Project description:This mouse kidney outer cortex proteomics data set is part of multi-omic approach in a mouse unilateral nephrectomy model to identify signaling processes associated with compensatory hypertrophy of the renal proximal tubule.
Project description:Loss of a kidney results in compensatory growth of the remaining kidney, a phenomenon of considerable clinical importance. However, the mechanisms involved are largely unknown. Here, we used a multi-omic approach in a mouse unilateral nephrectomy model to identify signaling processes associated with compensatory hypertrophy of the renal proximal tubule. Morphometry applied to microdissected proximal tubules showed that growth of the proximal tubule involves a marked, rapid increase in cell volume rather than cell number. Measurements of DNA accessibility (ATAC-seq), transcriptome (RNA-seq) and proteome (quantitative protein mass spectrometry) independently identified patterns of change that are indicative of activation of the lipid-regulated transcription factor, PPARα. Activation of PPARα by fenofibrate administration increased proximal tubule cell size, while genetic deletion of PPARα in mice decreased it. The results indicate that PPARα is an important determinant of proximal tubule cell size and is a likely mediator of compensatory proximal tubule hypertrophy.
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:Compensation is a physiological response that occurs during chemical exposure to maintain homeostasis. Because compensatory responses are not usually considered adverse effects, it is important to understand compensatory mechanisms for chemical risk assessment. Although the kidney is a major target organ for toxicity, there is controversy over whether hyperplasia or hypertrophy contributes to the compensatory mechanism, and there is limited information to apply for chemical risk assessment. In the current study, compensatory mechanisms of the kidney were investigated in a unilateral nephrectomy (UNx) model using adult male and female rats. In residual kidneys of male and female rats after UNx, 5-bromo-2'-deoxyuridine-labeling indices and mRNA expression of cell cycle-related genes were increased, although there were no fluctuations in mRNA expression of transforming growth factor-β1, which contributes to hypertrophy in renal tubules. Pathway analysis using mRNA expression data from a cDNA microarray revealed that canonical pathways related to cell proliferation were mainly activated and that forkhead box M1 (FOXM1) was an upstream regulator of compensatory cell proliferation in residual kidneys of male and female rats. cDNA microarray for microRNAs (miRNAs) demonstrated that 9 miRNAs were downregulated in residual kidneys, and mRNA/miRNA integrated analysis indicated that miRNAs were associated with the expression of factors downstream of FOXM1. Overall, these results suggested that FOXM1-mediated hyperplasia rather than hypertrophy contributed to compensatory mechanisms in the kidney and that miRNAs regulated downstream FOXM1 signaling. These results will be beneficial for evaluating nephrotoxicity in chemical risk assessment and for developing new biomarkers to predict nephrotoxicity.
Project description:Compensation is a physiological response that occurs during chemical exposure to maintain homeostasis. Because compensatory responses are not usually considered adverse effects, it is important to understand compensatory mechanisms for chemical risk assessment. Although the kidney is a major target organ for toxicity, there is controversy over whether hyperplasia or hypertrophy contributes to the compensatory mechanism, and there is limited information to apply for chemical risk assessment. In the current study, compensatory mechanisms of the kidney were investigated in a unilateral nephrectomy (UNx) model using adult male and female rats. In residual kidneys of male and female rats after UNx, 5-bromo-2'-deoxyuridine-labeling indices and mRNA expression of cell cycle-related genes were increased, although there were no fluctuations in mRNA expression of transforming growth factor-β1, which contributes to hypertrophy in renal tubules. Pathway analysis using mRNA expression data from a cDNA microarray revealed that canonical pathways related to cell proliferation were mainly activated and that forkhead box M1 (FOXM1) was an upstream regulator of compensatory cell proliferation in residual kidneys of male and female rats. cDNA microarray for microRNAs (miRNAs) demonstrated that 9 miRNAs were downregulated in residual kidneys, and mRNA/miRNA integrated analysis indicated that miRNAs were associated with the expression of factors downstream of FOXM1. Overall, these results suggested that FOXM1-mediated hyperplasia rather than hypertrophy contributed to compensatory mechanisms in the kidney and that miRNAs regulated downstream FOXM1 signaling. These results will be beneficial for evaluating nephrotoxicity in chemical risk assessment and for developing new biomarkers to predict nephrotoxicity.
Project description:Compensation is a physiological response that occurs during chemical exposure to maintain homeostasis. Because compensatory responses are not usually considered adverse effects, it is important to understand compensatory mechanisms for chemical risk assessment. Although the kidney is a major target organ for toxicity, there is controversy over whether hyperplasia or hypertrophy contributes to the compensatory mechanism, and there is limited information to apply for chemical risk assessment. In the current study, compensatory mechanisms of the kidney were investigated in a unilateral nephrectomy (UNx) model using adult male and female rats. In residual kidneys of male and female rats after UNx, 5-bromo-2'-deoxyuridine-labeling indices and mRNA expression of cell cycle-related genes were increased, although there were no fluctuations in mRNA expression of transforming growth factor-β1, which contributes to hypertrophy in renal tubules. Pathway analysis using mRNA expression data from a cDNA microarray revealed that canonical pathways related to cell proliferation were mainly activated and that forkhead box M1 (FOXM1) was an upstream regulator of compensatory cell proliferation in residual kidneys of male and female rats. cDNA microarray for microRNAs (miRNAs) demonstrated that 9 miRNAs were downregulated in residual kidneys, and mRNA/miRNA integrated analysis indicated that miRNAs were associated with the expression of factors downstream of FOXM1. Overall, these results suggested that FOXM1-mediated hyperplasia rather than hypertrophy contributed to compensatory mechanisms in the kidney and that miRNAs regulated downstream FOXM1 signaling. These results will be beneficial for evaluating nephrotoxicity in chemical risk assessment and for developing new biomarkers to predict nephrotoxicity.
Project description:The mechanism driving the remarkable ability of the remaining kidney to enlarge and increase its function following removal of its contralateral pair remains elusive. To explore the pathways driving compensatory renal hypertrophy, comprehensive RNA-seq transcriptional studies in the kidneys of mice undergoing hypertrophy 24, 48 and 72 hours following nephrectomy have been undertaken and compared with mice undergoing sham operations. The results reveal substantial time dependent enhancement of cholesterol biosynthesis pathways, increases in mitochondrial gene expression and cell cycle perturbations. Single nuclei RNA-Seq 24 hours post nephrectomy was used to further explore cholesterol biosynthesis signature and its driver SREBP2. In a cell specific manner, snRNA-seq demonstrated that SREBP2 activity increases in proximal tubules and medullary thick ascending limb and is responsible for cell size regulation following IGF-1 stimulation. These results suggest a previously undescribed role for SREBP2 in the mechanism underlying compensatory renal hypertrophy. This mechanism might be amenable to therapeutic manipulation to enhance kidney size and function.
Project description:Transcriptome analysis was done after warm renal ischemia-reperfusion injury (IRI) in a rat model. Earlier studies have shown a protective effect of prior unilateral nephrectomy (UNx) against IRI in the remaining, contralateral kidney compared to a non-neprectomized control group. We aimed at identifying the underlying molecular mechanisms. We used the Affymetrix Clariom D array (formerly known as RTA 1.0 st.) Array data was processed in the Affymetrix Console Software.
Project description:Purpose: Experiments were done in mice undergoing unilateral nephrectomy (UNx) and sham nephrectomy. At specific time points (24 hours and 72 hours) after surgery, the earliest first portion of the kidney proximal tubule (PT-S1) and the cortical collecting duct (CCD) were manually micro-dissected and utilized for transcriptomic analysis by single-tubule small sample RNA-Seq and single-tubule ATAC seq. Methods: We carried out ATAC-sequencing in microdissected ealiest portion of proximal tubules (PT-S1) from mice with or without (sham) unilateral nephrectomy (UNx). Each group (Sham or UNx) has 3 biological replicates. Results and conclusion: ATAC-seq peaks in microdissected PT-S1 revealed a predominance of binding site motifs corresponding to PPARα.
Project description:Purpose: Experiments were done in mice undergoing unilateral nephrectomy (UNx) and sham nephrectomy. At specific time points (24 hours and 72 hours) after surgery, the earliest first portion of the kidney proximal tubule (PT-S1) and the cortical collecting duct (CCD) were manually micro-dissected and utilized for transcriptomic analysis by single-tubule small sample RNA-Seq. Methods: We carried out RNA-sequencing in microdissected ealiest portion of proximal tubules (PT-S1) or cortical collecting duct (CCD) from mice with or without (sham) unilateral nephrectomy (UNx). Each group (Sham or UNx) has 3-5 biological replicates. Results and conclusion: RNA-Seq in microdissected PT-S1 at 24 hours showed that peroxisome proliferator-activated receptor alpha (PPARα) target genes were strongly upregulated. RNA-Seq in microdissected PT-S1 at 72 hours showed that cell cycle related genes were strongly upregulated. RNA-Seq in microdissected CCD at both 24 hours and 72 hours showed that cell cycle related genes were strongly upregulated.