Molecular fingerprint of the podocyte reveals novel gene regulatory networks
Ontology highlight
ABSTRACT: The thorough characterization of the transcriptome of endogenous podocytes has been hampered by low yields of cell isolation procedures. Here we introduce a double fluorescent reporter mouse model combined with an optimized bead perfusion protocol and efficient single cell dissociation yielding more than 500,000 podocytes per mouse allowing for global, unbiased downstream applications. Combining mRNA transcriptional profiling revealed programs of highly specific gene regulation tightly controlling cytoskeleton, cell differentiation, endosomal transport and peroxisome function in podocytes. Strikingly, the analyses further predict that these podocyte-specific gene regulatory networks are accompanied by alternative splicing of respective genes. In summary, the presented M-bM-^@M-^XomicsM-bM-^@M-^Y approach will facilitate the discovery and integration of novel gene, protein and organelle regulatory networks that deepen our systematic understanding of podocyte biology. To compare gene expression of glomerulus podocytes versus non-podocytes 5 replicates of 4 pooled mice were used. Data were normalized by robust multi-chip analysis. Exon expression values were summarised to the core meta probesets, as defined by Affymetrix, using the oligo library from R.
Project description:Purpose: Next-generation sequencing (NGS) was used to define the transcriptome of native mouse podocytes and non-podocytes glomerular cells as part of a project aiming to define the molecular fingerprint of mouse podocytes. Method: Glomeruli from 29 Gt(ROSA)26Sortm4(ACTB-tdTomato,-EGFP)Luo/J x hNPHS2Cre mice at the age of 10 weeks were purified and a single cell solution was prepared to seperate GFP-expressing (podocytes) and GFP-negative (non-podocytes glomerular cells) cells by FACS sorting. RNA was extracted and prepared for further analysis using directional, polyA+ library preparation. An Illumina HiSeq2500 was used for a paired-end sequencing of 100 cycles . Salmon and Sleuth were used for downstream analysis. Results: A total of 100 Million reads each from podocytes and non-podocytes glomerular cells could be used for further analysis.
Project description:Kidney podocytes and their slit diaphragms contribute to prevent urinary protein loss. T cell from patients with systemic lupus erythematosus display increased expression of calcium/calmodulin kinase IV (CaMKIV). Here we evaluated the functional role of CaMKIV in lupus nephritis (LN) using kidney biopsy specimens and human podocyte cell line (AB8/13). We found that exposure of podocytes to IgG from LN patients resulted in entry of IgG into the cytoplasm. CaMKIV expression was found to be increased in podocytes of LN kidney biopsy specimens and exposure to IgG from LN patients. IgG entered podocytes using the FcRn receptor because when podocytes where treated with FcRn siRNA less IgG was found in the cytoplasm. The DNA microarray studies of podocytes exposed to LN IgG revealed that genes that are related to the activation of immune cells or podocyte damage were upregulated. These genes included CD86, CaMKIV, PTPN22, PDE5A, CD47 and MALT1. Interestingly, CD86 expression decreased after silencing CaMKIV in podocytes. Also, in situ hybridization experiments showed that the expression of CD86 was reduced in podocytes from MRL/lpr.camkivM-bM-^HM-^R/M-bM-^HM-^R mice. IgG from LN patients may enter podocytes through the FcRn and causes the upregulation of a distinct set of genes which may alter podocyte function. Upregulation of CaMKIV appears to precede that of genes known to be linked to podocyte damage such as CD86. These findings may indicate that inhibition of CaMKIV may prove of clinical use in patients with LN. IgG Purification Kits (Dojindo Molecular Technologies, Inc.) are used for isolation and purification of immunoglobulin G of healthy and normal individual according to the manufacturerM-bM-^@M-^Ys protocol. Flow through the column was used for non IgG binding samples. Cultured human podocytes with IgG purified from sera of normal individuals and LN patient for 24 hr were collected for RNA.
Project description:We compared mRNA profiles of isolated glomeruli versus sorted podocytes between diabetic and control mice. IRG mice crossed with eNOS-/- mice were further bred with podocin-rTTA and TetON-Cre mice to permanently label podocytes before the diabetic injury. Diabetes was induced by injection of streptozotocin. mRNA profiles of isolated glomeruli and sorted podocytes from diabetic and control mice at 10 weeks after induction of diabetes were examined. Consistent with the previous reports, expression of podocyte-specific markers in the glomeruli were down-regulated in the diabetic mice compared to controls. However, these differences disappeared when mRNA levels were corrected for podocyte number per glomerulus. Interestingly, the expression of these markers was not altered in sorted podocytes from diabetic mice, suggesting that the reduced expression of podocyte markers in isolated glomeruli is likely a secondary effect of reduced podocyte number, rather than the loss of differentiation markers. Analysis of the differentially expressed genes in diabetic mice also revealed distinct up-regulated pathways in the glomeruli (mitochondrial function and oxidative stress) and podocytes (actin organization). In conclusion, our data suggest that podocyte-specific gene expression in transcriptome obtained from the whole glomeruli may not represent those of podocytes in the diabetic kidney. We compared mRNA profiles of isolated glomeruli versus sorted podocytes between diabetic and control mice.
Project description:Renal endothelial cells (RECs) from glomerular cortical and medullary kidney compartments are exposed to different microenvironmental conditions. Upon dehydration medullary RECs (mRECs) are exposed to extreme hyperosmolarity. However the heterogeneous phenotypes of RECs remain in-completely inventoried and how mRECs respond to dehydration is unknown. By single cell RNA-sequencing of >40000 RECs we identified 24 (including 8 novel) REC phenotypes highlighting extensive heterogeneity of RECs between and within the cortex glomeruli and medulla. In response to dehydration mRECs upregulated primarily the expression of genes involved in the hypoxia response glycolysis and surprisingly oxidative phosphorylation (OXPHOS). In vitro mRECs increased oxygen consumption in response to hyperosmolarity presumably to sustain ATP production for Na+/K+ ATPase pump-mediated salt excretion and to generate metabolic water during OXPHOS in order to counteract mREC hyperosmolarity unveiling a previously underappreciated role of OXPHOS. Overall RECs exhibit extensive heterogeneity and plasticity to adapt their metabolic transcriptome to overcome dehydration.
Project description:We analyzed the role of MOF in primary MEFs and differentiated podocytes in response to Adriamycin. Mof was deleted in MEFs using the Cre-ERT2 trasgene, while Mof was knockdown in podocytes using shRNA infection. Samples were treated with Adriamycin for 24 hours and gene expression changes analysed. Analysis of gene expression changes upon Mof depletion in two cell lines, MEFs and podocytes, with and without Adriamycin
Project description:Mouse glomeruli and brain capillary fragments were prepared. Podocytes were separated from isolated glomeruli from 8-day-old Podocin-Cre, Z/EG double transgenic mice as follows: Isolated glomeruli were incubated with trypsin solution containing 0.2 % trypsin-EDTA (Sigma-Aldrich), 100ug/ml Heparin and 100U/ml DNase I in PBS for 25 min at 37 degree, with mixing by pipetting every 5 min. The trypsin was inactivated with soybeans trypsin inhibitor (Sigma-Aldrich) and the cell suspension sieved through a 30 um pore size filter (BD bioscience, Franklin Lakes, NJ). Cells were collected by centrifugation at 200 x g for 5 min at 4 degree and resuspended in 1ml PBS supplemented with 0.1 % BSA. To separate GFP-expressing (GFP+) and GFP-negative (GFP-) cells, glomerular cell were sorted using a FACSVantage SE (BD, San Jose, CA, USA) operating at a sheath pressure of 22 psi. Autofluorescent cells were excluded by analyzing the emission of orange light (585 nm). To allow for standardization of results, the samples such as glomerular RNA, brain capillary RNA, rest of kidnay RNA, podocyte RNA and foxc2 glomreular RNA were hybridized in competition with common reference samples.
Project description:Analysis of gene expression changes in differentiated human podocytes treated with the serum from patients with (DKD+) or without (DKD-) diabetic kidney disease when compared to normal subjects (C). The hypothesis is that the three groups can be distinghed by their differential gene expression pattern. The results obtained revealed important information regarding differences in gene expression in human podocytes treated with the serum from patients with (DKD+) or without (DKD-) diabetic kidney disease when compared to normal subjects (C). Human podocytes were contacted with the serum from patients with diabetes and kidney disease (DKD+) or without kidney disease (DKD-) and compared to normal human podocytes contacted with serum from patients without diabetes (C).
Project description:Analysis of gene expression changes in differentiated human podocytes treated with the serum from patients with (DKD+) or without (DKD-) diabetic kidney disease when compared to normal subjects (C). The hypothesis is that the three groups can be distinghed by their differential gene expression pattern. The results obtained revealed important information regarding differences in gene expression in human podocytes treated with the serum from patients with (DKD+) or without (DKD-) diabetic kidney disease when compared to normal subjects (C). Human podocytes were contacted with the serum from patients with diabetes and kidney disease (DKD+) or without kidney disease (DKD-) and compared to normal human podocytes contacted with serum from patients without diabetes (C).
Project description:Nephrotic syndrome (NS) occurs when the glomerular filtration barrier becomes excessively permeable leading to massive proteinuria. In childhood NS, dysregulation of the immune system has been implicated and increasing evidence points to the central role of podocytes in the pathogenesis. Children with NS are typically treated with an empiric course of glucocorticoid (Gc) therapy; a class of steroids that are activating ligands for the glucocorticoid receptor (GR) transcription factor. Although Gc-therapy has been the cornerstone of NS management for decades, the mechanism of action, and target cell, remain poorly understood. We tested the hypothesis that Gc acts directly on the podocyte to produce clinically useful effects without involvement of the immune system. In human podocytes, we demonstrated that the basic GR-signalling mechanism is intact and that Gc induced an increase in podocyte barrier function. To gain mechanistic insight we performed RNA microarray and ChIP-sequencing and identified Gc regulation of motility genes.