Expression and regulation of adrenomedullin in renal glomerular podocytes

doi:10.1016/j.bbrc.2005.02.142

Biochemical and Biophysical Research Communications

Volume 330, Issue 1, 29 April 2005, Pages 178-185

https://doi.org/10.1016/j.bbrc.2005.02.142 Get rights and content

Abstract

Adrenomedullin (AM) is postulated to exert organ-protective effects. It is expressed in the renal glomeruli, but its roles in the glomerular podocytes have been poorly elucidated. In the present study, we investigated the expression and regulation of AM in recently established conditionally immortalized mouse podocyte cell line in vitro and podocyte injury model in vivo. The cultured differentiated podocytes expressed AM mRNA and secreted measurable amount of AM. AM secretion from the podocytes was increased by H₂O₂, hypoxia, puromycin aminonucleoside (PAN), albumin overload, and TNF-α. Real-time RT-PCR analysis revealed that AM mRNA expression in the podocytes was enhanced by PAN and TNF-α, both of which were suppressed by mitochondrial antioxidants. Furthermore, AM expression was upregulated in the glomerular podocytes of PAN nephrosis rats. These results indicated that AM expression in the podocytes was upregulated by stimuli or condition relevant to podocyte injury, suggesting its potential role in podocyte pathophysiology.

Section snippets

Materials and methods

Cell culture of mouse podocytes. We used conditionally immortalized mouse podocyte cell line established by Mundel et al. [7]. In brief, this cell line was generated from renal glomeruli of transgenic mice harboring thermo-sensitive mutant of the SV-40 large T antigen, which is under the control of the H-2K^b-promoter whose activity is inducible by γ-interferon. The podocyte lineage was selected as WT-1-positive cells. To propagate, podocytes between passage 14 and 20 were cultivated in RPMI

AM mRNA was expressed in cultured podocytes

The podocyte cell line, when cultured under permissive condition, proliferated with undifferentiated cobblestone-like appearance (Fig. 1A). Under nonpermissive condition, on the other hand, most of the cells became growth arrested and acquired characteristics of differentiated podocytes, such as cell process elongation by day 7 (Fig. 1B).

We first examined whether AM mRNA was expressed in our podocyte cell line cultivated under nonpermissive condition for 10–14 days. RT-PCR analysis showed that

Discussion

In the present study, we demonstrated that AM is synthesized in the glomerular podocyte cell line established by Mundel et al. AM expression is upregulated in response to oxidative stress, hypoxia, PAN, protein overload, and TNF-α in the cultured podocytes in vitro, and in the glomerular podocytes of PAN nephrosis rats in vivo. These modulatory patterns of AM in response to various stimuli suggest that AM is involved in the podocyte damage.

This is the first paper indicating that AM is expressed

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View full text

Expression and regulation of adrenomedullin in renal glomerular podocytes

Abstract

Section snippets

Materials and methods

AM mRNA was expressed in cultured podocytes

Discussion

Exp. Cell Res.

Kidney Int.

Kidney Int.

Biochem. Biophys. Res. Commun.

Biochem. Biophys. Res. Commun.

Kidney Int.

Biochem. Biophys. Res. Commun.

Kidney Int.

Peptides

Semin. Nephrol.

Peptides

Peptides

Podocyte biology and response to injury

J. Am. Soc. Nephrol.

Cell biology of the glomerular podocyte

Physiol. Rev.

Progressive renal failure—inability of podocytes to replicate and the consequences for development of glomerulosclerosis

Nephrol. Dial. Transplant.

Rat glomerular epithelial cells in culture express characteristics of parietal, not visceral, epithelium

J. Am. Soc. Nephrol.

Rat glomerular cells do not express podocytic markers when cultured in vitro

Lab. Invest.

Visceral epithelial cells in rat glomerular cell culture

Eur. J. Cell Biol.

Podocyte damage is a critical step in the development of glomerulosclerosis in the uninephrectomised-desoxycorticosterone hypertensive rat

Virchows Arch.

Documentation of angiotensin II receptors in glomerular epithelial cells

Am. J. Physiol.

Catecholamines modulate podocyte function

J. Am. Soc. Nephrol.

Role of natriuretic peptide receptor type C in Dahl salt-sensitive hypertensive rats

Hypertension