Angiotensin II Type I Receptor Agonistic Autoantibody Induces Podocyte Injury via Activation of the TRPC6- Calcium/Calcineurin Pathway in Pre-Eclampsia.

Abstract

BACKGROUND/AIMS:

Angiotensin II type I receptor agonistic autoantibody (AT1-AA) is closely related to pre-eclampsia, which is characterized by proteinuria and hypertension. AT1-AA has been shown to enhance the effect of AngII in pre-eclampsia, such as production of endothelin-1, activation of ROS, and vasoconstriction, which are considered to be associated with hypertension; however, whether or not AT1-AA participates in podocyte damage leading to the generation of proteinuria has not been reported. In this study we investigated the role of pre-eclamptic serum AT1-AA on podocytes and the mechanism underlying the generation of proteinuria.

METHODS:

The levels of AT1-AA isolated from pre-eclamptic sera were determined by an enzyme-linked immunosorbent assay. Human podocytes were cultured in vitro and treated with various concentrations of AT1-AA. Whether or not an ERK1/2 inhibitor and TRPC6 siRNA inhibit the effect of AT1-AA on podocytes was determined. Western blot was used to detect the expression of podocyte-specific proteins (nephrin, synaptopodin, and podocin) and the phosphorylation of ERK1/2 and TRPC6. The arrangement of F-actin was observed by immunofluorescence. A Calcineurin Cellular Activity Assay Kit was used to detect calcineurin activity. Changes in the intracellular Ca2+ concentration was determined by confocal laser.

RESULTS:

AT1-AA induced a decrease in podocyte-specific protein expression and calcineurin activity and increased expression of p-ERK1/2 and TRPC6 protein and the intracellular Ca2+ concentration. Immunofluorescence revealed rearrangement of F-actin. PD98059, an inhibitor of ERK1/2, and TRPC6 siRNA attenuated the decreased expression of podocyte-specific proteins and decreased intracellular Ca2+ concentration. The expression of TRPC6 was reduced following the addition of ERK1/2 inhibitor.

CONCLUSION:

AT1-AA induced podocyte damage in a dose-dependent manner. The underlying mechanism might involve activation of the TRPC6 -calcium/calcineurin pathway. This study provides new details regarding podocyte injury and the mechanism underlying the generation of proteinuria in pre-eclampsia.

• Authors: Ying Yu, Lihong Zhang, Guang Xu, Zhenghong Wu, Qian Li, Yong Gu, Jianying Niu
• Journal: Kidney & blood pressure research (Kidney Blood Press Res) Vol. 43 Issue 5 Pg. 1666-1676 ( 2018) ISSN: 1423-0143 [Electronic] Switzerland
• PMID: 30380548 (Publication Type: Journal Article)
• Copyright: © 2018 The Author(s). Published by S. Karger AG, Basel.

Chemical References

• Autoantibodies
• Receptor, Angiotensin, Type 1
• TRPC6 Cation Channel
• Calcineurin
• Calcium

Topics

• Adult
• Autoantibodies (blood, pharmacology)
• Calcineurin (metabolism)
• Calcium (metabolism)
• Cells, Cultured
• Female
• Humans
• Metabolic Networks and Pathways (drug effects)
• Podocytes (drug effects, metabolism, pathology)
• Pre-Eclampsia (blood, metabolism)
• Pregnancy
• Receptor, Angiotensin, Type 1 (immunology, therapeutic use)
• TRPC6 Cation Channel (metabolism)