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Microarray Study Reveals Hormone-Modulated Gene Transcription During Human Podocyte Differentiation

ABSTRACT: Glomerular podocytes are highly differentiated kidney cells that constitute one of the key components responsible for removing toxins and metabolic waste while preserving nutrients in the bloodstream in the renal glomerulus. In addition, podocytes contribute significantly to the formation of the glomerular basement membrane and the integrity of the vascular endothelium. Thus, podocyte injury and/or loss of podocytes results in impaired blood filtration and causes many common renal diseases characterized by severe proteinuria (protein in the urine) and hypoalbuminemia (low levels of blood albumin). Small lipopholic molecules such as steroids, fatty acids, prostaglandins and vitamin metabolites control many aspects of animal development, cell proliferation and differentiation, and homeostasis through binding to their intracellular receptors. Upon binding to their cognate ligands, these nuclear receptors (NRs) are capable of turning on or off of an array of gene networks. By doing so, they regulate a whole spectrum of cellular activities. The ability of small molecule hormones to regulate NR activity makes them excellent pharmaceutical targets. Clinical evidence and animal studies have implicated several NRs in contributing to podocyte development and disease. Recent studies from animals and cultured human or mouse podocytes indicate that synthetic hormones including estradiol, glucocorticoid, retinoid, pioglitazone, vitamin D3 and WY-14643 protect or rescue podocytes from experimental injury. Post treatment of injured podocytes with ligands for the above-mentioned NRs restores cytoskeletal architecture of the podocytes. Nonetheless, the mechanisms underlying the ability of these hormones in protecting podocytes remain largely unexplored. This is partly due to our limited knowledge of the target genes controlled by these hormones. In order to elucidate the mechanisms by which Dex, VD3 and ATRA elicit their renoprotective activity, we initiate a gene expression profiling study to identify the target genes of these hormones in cultured human podocytes.

ORGANISM(S): Homo sapiens

PROVIDER: GSE39823 | GEO | 2013/05/30

SECONDARY ACCESSION(S): PRJNA171922

REPOSITORIES: GEO

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Project description:Glomerular podocytes are highly differentiated kidney cells that constitute one of the key components responsible for removing toxins and metabolic waste while preserving nutrients in the bloodstream in the renal glomerulus. In addition, podocytes contribute significantly to the formation of the glomerular basement membrane and the integrity of the vascular endothelium. Thus, podocyte injury and/or loss of podocytes results in impaired blood filtration and causes many common renal diseases characterized by severe proteinuria (protein in the urine) and hypoalbuminemia (low levels of blood albumin). Small lipopholic molecules such as steroids, fatty acids, prostaglandins and vitamin metabolites control many aspects of animal development, cell proliferation and differentiation, and homeostasis through binding to their intracellular receptors. Upon binding to their cognate ligands, these nuclear receptors (NRs) are capable of turning on or off of an array of gene networks. By doing so, they regulate a whole spectrum of cellular activities. The ability of small molecule hormones to regulate NR activity makes them excellent pharmaceutical targets. Clinical evidence and animal studies have implicated several NRs in contributing to podocyte development and disease. Recent studies from animals and cultured human or mouse podocytes indicate that synthetic hormones including estradiol, glucocorticoid, retinoid, pioglitazone, vitamin D3 and WY-14643 protect or rescue podocytes from experimental injury. Post treatment of injured podocytes with ligands for the above-mentioned NRs restores cytoskeletal architecture of the podocytes. Nonetheless, the mechanisms underlying the ability of these hormones in protecting podocytes remain largely unexplored. This is partly due to our limited knowledge of the target genes controlled by these hormones. In order to elucidate the mechanisms by which Dex, VD3 and ATRA elicit their renoprotective activity, we initiate a gene expression profiling study to identify the target genes of these hormones in cultured human podocytes. The temperature-sensitive cultured human podocytes (HPCs) were maintained in culture media of RPMI supplemented with 10% FBS, 1% antibiotics and the Insulin-Transferrin-Selenium at the permissive (undifferentiated) temperature of 33 Celsius degree. The 70%~80% confluent HPCs were induced to in vitro differentiate by culturing at 37 Celsius degree for 2 days then with incubation of vehicle (equal volume of DMSO), 100 nM all-trans retinoic acid (ATRA), 100 nM dexamethasone (Dex), or 100 nM vitamin D3 (VD3) treatment for 3 more days. The undifferentiated HPCs with vehicle (equal volume of DMSO) treatment was included as a control. The total RNAs of these cells were isolated using USB prepEase RNA spin kit following the manufacturer's instructions. Total 1 microgram RNA at 100 nanogram per microliter for each sample were sent for a single-channel gene expression microarray studies using HumanRef-8 chip (V3_0_R3_11282963) on Illumina BeadStation platform. The RNA were converted to aRNA and appropriately labelled using MessageAmp Biotin aRNA Amplification Kit (Ambion) following the manufacturer's instructions. The raw data were collected by scanning the chip on Illumina BeadStation. Background subtracted raw data were exported and the following analysis was done in R/Bioconductor environment. Thus, we were able to compare the gene expression profiles between differentiated and undifferentiated HPCs with or without hormone treatment.

Project description:Glomerular podocytes are highly differentiated cells that are key components of the kidney filtration units. The podocyte cytoskeleton builds the basis for the dynamic podocyte cytoarchitecture and plays a central role for proper podocyte function. Recent studies implicate that immunosuppressive agents including the mTOR-inhibitor everolimus have a protective role directly on the stability of the podocyte cytoskeleton. To elucidate mechanisms underlying mTOR-inhibitor mediated cytoskeletal rearrangements, we carried out microarray gene expression studies to identify target genes and corresponding pathways in response to everolimus. We analyzed the effect of everolimus in a puromycin aminonucleoside experimental in vitro model of podocyte injury. Upon treatment with puromycin aminonucleoside, microarray analysis revealed gene clusters involving cytoskeletal-associated pathways, adhesion, migration and extracellular matrix composition to be affected. Everolimus is capable of protecting podocytes from injury, both on the transcriptome and protein level. Rescued genes included TUBB2B and DCDC2, both involved in microtubule structure formation in neuronal cells but not identified in podocytes so far. Confirming gene expression data, Western-blot analysis in cultured podocytes showed an increase of TUBB2B and DCDC2 protein after everolimus treatment, and immunohistochemistry in healthy control kidneys confirmed a podocyte-specific expression. Microtubule-inhibitor experiments led to a maldistribution of TUBB2B and DCDC2 as well as an aberrant reorganization of the actin cytoskeleton. Tubb2bbrdp/brdp mice showed a delay in glomerular podocyte and capillary development. Taken together, our study suggests that off-target, non-immune mediated effects of the mTOR-inhibitor everolimus on the podocyte cytoskeleton might involve regulation of microtubules, revealing a potential novel role of TUBB2B and DCDC2 in glomerular podocyte development We analyzed the effect of everolimus on gene expression in a puromycin aminonucleoside experimental in vitro model of podocyte injury using microarrays

Project description:Indoxyl sulfate (IS) is a uremic toxin and ligand of the aryl-hydrocarbon receptor (Ahr), a transcriptional regulator. Elevated serum IS may contribute to the progression of kidney disease. Therefore, we assessed mouse podocyte damage mediated by IS. Ahr was predominantly localized to the podocyte nucleus in vivo and in vitro. In isolated glomeruli, IS-exposure for 2 – 24 h induced Cyp1a1 expression, the most sensitive biomarker of Ahr activation. Mice exposed to IS for 4–8 weeks exhibited microalbuminuria, and mild glomerular injury characterized by ischemic changes, partial podocyte foot process effacement, as well as vascular and tubulointerstitial damage. Chronically IS-exposed kidneys exhibited decreased mRNA, decreased protein levels, and altered staining patterns for podocin, synaptopodin, and non-muscle myosin IIA (Myh9). Immortalized podocytes, upon differentiation, exhibited Ahr nuclear translocation beginning 30 min after 1 mM IS-exposure. At 2 h, there was a dose-dependent decrease in podocyte mRNA expression of WT1, Podxl, Snypo, Myh9, Actn4, and Cd2ap. After 24 h of exposure to IS, podocytes were smaller, had fewer actin/Myh9 fibers, and decreased viability. Ahr-RNAi decreased mRNA expression of podocyte-specific proteins and inhibited Cyp1a1 induction by IS-exposure. Combinations of Ahr-RNAi and IS-exposure further decreased Myh9 expression. In immortalized human podocytes, IS treatment caused cell injury, decreased mRNA expression of podocyte-specific proteins, integrins, collagens, cytoskeletal proteins, and bone morphogenetic proteins, and increased cytokine and chemokine expression. Thus, chronic IS-exposure causes glomerular damage by activating Ahr, altering podocyte function, differentiation, and morphology, and inducing a pro-inflammatory phenotype. Podocyte cells treated with Indoxyl sulfate, a uremic toxin and aryl-hydrocarbon receptor ligand, mediates progressive glomerular disease by damaging podocytes Human podocyte cell line treated with or without 3-Indoxyl sulfate (1mM/0.1%DMSO) in three replications

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Microarray Study Reveals Hormone-Modulated Gene Transcription During Human Podocyte Differentiation

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