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Podocytes use FcRn to clear IgG from the glomerular basement membrane

ABSTRACT: The glomerular filtration barrier prevents large serum proteins from being lost into the urine. It is not known, however, why the filter does not routinely clog with large proteins that enter the glomerular basement membrane (GBM). Here we provide evidence that an active transport mechanism exists to remove immunoglobulins that accumulate at the filtration barrier. We found that FcRn, an IgG and albumin transport receptor, is expressed in podocytes and functions to internalize IgG from the GBM. Mice lacking FcRn accumulated IgG in the GBM as they aged and tracer studies showed delayed clearance of IgG from the kidneys of FcRn deficient mice. Supporting a role for this pathway in disease, saturating the clearance mechanism potentiated the pathogenicity of nephrotoxic sera. These studies support the idea that podocytes play an active role in removing proteins from the GBM and suggest that genetic or acquired impairment of the clearance machinery is likely to be a common mechanism promoting glomerular diseases. Keywords: Unique cell type expression analysis

ORGANISM(S): Mus musculus

PROVIDER: GSE10017 | GEO | 2008/01/01

SECONDARY ACCESSION(S): PRJNA108205

REPOSITORIES: GEO

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Transcription profiling of mouse Podocytes reveal use of FcRn to clear IgG from the glomerular basement membrane

Project description:The glomerular filtration barrier prevents large serum proteins from being lost into the urine. It is not known, however, why the filter does not routinely clog with large proteins that enter the glomerular basement membrane (GBM). Here we provide evidence that an active transport mechanism exists to remove immunoglobulins that accumulate at the filtration barrier. We found that FcRn, an IgG and albumin transport receptor, is expressed in podocytes and functions to internalize IgG from the GBM. Mice lacking FcRn accumulated IgG in the GBM as they aged and tracer studies showed delayed clearance of IgG from the kidneys of FcRn deficient mice. Supporting a role for this pathway in disease, saturating the clearance mechanism potentiated the pathogenicity of nephrotoxic sera. These studies support the idea that podocytes play an active role in removing proteins from the GBM and suggest that genetic or acquired impairment of the clearance machinery is likely to be a common mechanism promoting glomerular diseases. Experiment Overall Design: Total RNA for genechip analysis was derived from two sources: Experiment Overall Design: 1) Primary mouse podocytes isolated by FACS sorting of collagenase digested glomeruli Experiment Overall Design: 2) In vitro differentiated conditionally immortalized mouse podocyte cell line. Experiment Overall Design: After obtaining genechip data, the expression of various IgG and albumin receptors was queried in the genechip data and then confirmed by RT-PCR.

2008-06-11 | E-GEOD-10017 | biostudies-arrayexpress

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Expression data from cultured WT and NCK1/2 knockout mouse podocyte cells

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2022-04-29 | GSE184235 | GEO

Mus musculus

Project description:Podocytes use FcRn to clear IgG from the glomerular basement membrane

| PRJNA108205 | ENA

Role of calcium/calmodulin-dependent kinase type IV in podocyte function in lupus nephritis

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2014-08-01 | E-GEOD-55768 | biostudies-arrayexpress

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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.camkiv−/− 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.

2014-08-01 | GSE55768 | GEO

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