Expression of filtrin in human glomerular diseases

Pekka Ihalmo, Holger Schmid, Maria Pia Rastaldi, Deborah Mattinzoli, Robyn G. Langham, Pauliina Luimula, Riika Kilpikari, Markus Lassila, Richard E. Gilbert, Dontscho Kerjaschki, Matthias Kretzler, Harry Holthöfer

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Background. Filtrin (NEPH3/KIRREL2) is a recently characterized member of the nephrin-like proteins of the immunoglobulin superfamily, and it has been suggested to participate in the maintenance of the glomerular filtration barrier in the kidney. In this study, the gene and protein expression of filtrin were examined in patients with acquired proteinuric diseases. Methods. Filtrin mRNA levels in renal biopsies were measured with quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) in two sets of patients with proteinuria. The mRNA levels were normalized to the housekeeping gene GAPDH and also related to the podocyte-specific genes nephrin and podocin. Immunofluorescence microscopy was employed to explore changes in the glomerular distribution of filtrin. Results. Reduced glomerular expression of filtrin mRNA was observed in all studied diagnostic groups. In focal segmental glomerulosclerosis, the filtrin mRNA level was only one-tenth of the control samples (P ≈ 5.0 × 10-6), and this finding was confirmed in a second set of samples. The ratios of filtrin to nephrin and podocin demonstrated a marked decrease in the expression of filtrin relative to the podocyte marker genes. However, no correlation between the expression of filtrin and the levels of serum creatinine and proteinuria was observed. Immunostaining showed changes in the expression pattern of filtrin in renal biopsies. Immunoelectron microscopic studies localized filtrin at the slit diaphragm of the podocyte foot processes. Conclusions. Down-regulation of the filtrin gene and protein expression in the renal biopsies together with the localization to the inter-podocyte filtration slit imply a potential role for this molecule in the pathogenesis of proteinuric diseases.

Original languageEnglish
Pages (from-to)1903-1909
Number of pages7
JournalNephrology Dialysis Transplantation
Volume22
Issue number7
DOIs
Publication statusPublished - Jul 2007

Fingerprint

Podocytes
Kidney
Messenger RNA
Biopsy
Proteinuria
Glomerular Filtration Barrier
Gene Expression
Focal Segmental Glomerulosclerosis
Proteins
Essential Genes
Diaphragm
Reverse Transcriptase Polymerase Chain Reaction
Fluorescence Microscopy
Genes
Immunoglobulins
Creatinine
Down-Regulation
Maintenance
Serum
nephrin

Keywords

  • Gene expression
  • Glomerulus
  • Kidney biopsy
  • Podocyte
  • Proteinuria

ASJC Scopus subject areas

  • Nephrology
  • Transplantation

Cite this

Ihalmo, P., Schmid, H., Rastaldi, M. P., Mattinzoli, D., Langham, R. G., Luimula, P., ... Holthöfer, H. (2007). Expression of filtrin in human glomerular diseases. Nephrology Dialysis Transplantation, 22(7), 1903-1909. https://doi.org/10.1093/ndt/gfm135

Expression of filtrin in human glomerular diseases. / Ihalmo, Pekka; Schmid, Holger; Rastaldi, Maria Pia; Mattinzoli, Deborah; Langham, Robyn G.; Luimula, Pauliina; Kilpikari, Riika; Lassila, Markus; Gilbert, Richard E.; Kerjaschki, Dontscho; Kretzler, Matthias; Holthöfer, Harry.

In: Nephrology Dialysis Transplantation, Vol. 22, No. 7, 07.2007, p. 1903-1909.

Research output: Contribution to journalArticle

Ihalmo, P, Schmid, H, Rastaldi, MP, Mattinzoli, D, Langham, RG, Luimula, P, Kilpikari, R, Lassila, M, Gilbert, RE, Kerjaschki, D, Kretzler, M & Holthöfer, H 2007, 'Expression of filtrin in human glomerular diseases', Nephrology Dialysis Transplantation, vol. 22, no. 7, pp. 1903-1909. https://doi.org/10.1093/ndt/gfm135
Ihalmo, Pekka ; Schmid, Holger ; Rastaldi, Maria Pia ; Mattinzoli, Deborah ; Langham, Robyn G. ; Luimula, Pauliina ; Kilpikari, Riika ; Lassila, Markus ; Gilbert, Richard E. ; Kerjaschki, Dontscho ; Kretzler, Matthias ; Holthöfer, Harry. / Expression of filtrin in human glomerular diseases. In: Nephrology Dialysis Transplantation. 2007 ; Vol. 22, No. 7. pp. 1903-1909.
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AU - Schmid, Holger

AU - Rastaldi, Maria Pia

AU - Mattinzoli, Deborah

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AU - Luimula, Pauliina

AU - Kilpikari, Riika

AU - Lassila, Markus

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N2 - Background. Filtrin (NEPH3/KIRREL2) is a recently characterized member of the nephrin-like proteins of the immunoglobulin superfamily, and it has been suggested to participate in the maintenance of the glomerular filtration barrier in the kidney. In this study, the gene and protein expression of filtrin were examined in patients with acquired proteinuric diseases. Methods. Filtrin mRNA levels in renal biopsies were measured with quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) in two sets of patients with proteinuria. The mRNA levels were normalized to the housekeeping gene GAPDH and also related to the podocyte-specific genes nephrin and podocin. Immunofluorescence microscopy was employed to explore changes in the glomerular distribution of filtrin. Results. Reduced glomerular expression of filtrin mRNA was observed in all studied diagnostic groups. In focal segmental glomerulosclerosis, the filtrin mRNA level was only one-tenth of the control samples (P ≈ 5.0 × 10-6), and this finding was confirmed in a second set of samples. The ratios of filtrin to nephrin and podocin demonstrated a marked decrease in the expression of filtrin relative to the podocyte marker genes. However, no correlation between the expression of filtrin and the levels of serum creatinine and proteinuria was observed. Immunostaining showed changes in the expression pattern of filtrin in renal biopsies. Immunoelectron microscopic studies localized filtrin at the slit diaphragm of the podocyte foot processes. Conclusions. Down-regulation of the filtrin gene and protein expression in the renal biopsies together with the localization to the inter-podocyte filtration slit imply a potential role for this molecule in the pathogenesis of proteinuric diseases.

AB - Background. Filtrin (NEPH3/KIRREL2) is a recently characterized member of the nephrin-like proteins of the immunoglobulin superfamily, and it has been suggested to participate in the maintenance of the glomerular filtration barrier in the kidney. In this study, the gene and protein expression of filtrin were examined in patients with acquired proteinuric diseases. Methods. Filtrin mRNA levels in renal biopsies were measured with quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) in two sets of patients with proteinuria. The mRNA levels were normalized to the housekeeping gene GAPDH and also related to the podocyte-specific genes nephrin and podocin. Immunofluorescence microscopy was employed to explore changes in the glomerular distribution of filtrin. Results. Reduced glomerular expression of filtrin mRNA was observed in all studied diagnostic groups. In focal segmental glomerulosclerosis, the filtrin mRNA level was only one-tenth of the control samples (P ≈ 5.0 × 10-6), and this finding was confirmed in a second set of samples. The ratios of filtrin to nephrin and podocin demonstrated a marked decrease in the expression of filtrin relative to the podocyte marker genes. However, no correlation between the expression of filtrin and the levels of serum creatinine and proteinuria was observed. Immunostaining showed changes in the expression pattern of filtrin in renal biopsies. Immunoelectron microscopic studies localized filtrin at the slit diaphragm of the podocyte foot processes. Conclusions. Down-regulation of the filtrin gene and protein expression in the renal biopsies together with the localization to the inter-podocyte filtration slit imply a potential role for this molecule in the pathogenesis of proteinuric diseases.

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KW - Podocyte

KW - Proteinuria

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