Hormones – Cytokines – Signaling
Kidney International (1999) 55, 1293–1302; doi:10.1046/j.1523-1755.1999.00393.x
Mesangial cells from diabetic NOD mice constitutively express increased density of atrial natriuretic peptide C receptors
Nicole Ardaillou, Sandrine Placier, Liliane Striker, Gary Striker and Raymond Ardaillou
Correspondence: Dr Raymond Ardaillou, INSERM Unité 489, Hôpital Tenon, 4, Rue de la Chine, 75970 Paris Cedex 20, FRANCE. E-mail: raymond.ardaillou@tnn.ap-hop-paris.fr
Received 29 June 1998; Revised 19 November 1998; Accepted 19 November 1998.
Abstract
Mesangial cells from diabetic NOD mice constitutively express increased density of atrial natriuretic peptide C receptors.
Background
Experimental evidence shows that natriuretic peptides (NPs) play a pathophysiological role in the glomerular hemodynamic abnormalities that occur in diabetes mellitus.
Methods
In this study, the cGMP response to NPs and the different subtypes of NP receptors were examined in mesangial cells derived from a genetic model of diabetes, the nonobese diabetic (NOD) mouse. Multiple mesangial cell lines were derived from diabetic (D-NOD) and nondiabetic (ND-NOD) adult mice and were studied at different passages.
Results
cGMP accumulation after stimulation by atrial NP (ANP) or C-type NP (CNP) was markedly inhibited in D-NOD cells irrespective of the glucose concentration (6 or 20 mM) in the culture medium. In contrast, NP receptor density measured from [125I]-ANP saturation binding curves was 7.5 times greater in D-NOD than in ND-NOD cells. No change in KD (200 pM in both cell lines) was observed. Competitive inhibition studies showed that 4-23 C-ANP, which is specific of clearance receptors (NPR-C), displaced 90% of the maximum fraction bound, suggesting the predominance of NPR-C in both cell lines. Further identification was obtained from RNase protection assay and reverse transcription-polymerase chain reaction, which also demonstrated the higher expression of NPR-C mRNA in D-NOD cells. In contrast, NPR-A mRNA was not modified. Increased expression of NPR-C in D-NOD cells was associated with an increase of ANP internalization rate at 37°C, indicating that these receptors were functional.
Conclusions
These studies demonstrate that the constitutive overexpression of NPR-C in D-NOD mesangial cells is associated with a decreased response of cGMP to ANP or CNP treatment. This could be due to the lesser availability of the peptides for binding to NPR-A or NPR-B or to an inhibitory effect on NP-dependent guanylate cyclase activity via the activation of NPR-C.
Keywords:
diabetes mellitus, natriuretic peptide, hemodynamics, glomerular filtration rate, IDDM, glomerulosclerosis
