Abstract
Angiotensin II (Ang II) is a key contributor to glomerular disease by predominantly resulting in podocyte injury, whereas the underlying molecular mechanisms has not been fully understood. This study aimed to investigate if and how ADP-ribosylation factor 6 (Arf6), a small GTP-binding protein, involves Ang II-induced cellular injury in cultured human podocytes. Cellular injury was evaluated with caspase 3 activity, reactive oxygen species (ROS) level and TUNEL assay. Arf6 activity was measured using an Arf6-GTP Pull-Down Assay. Ang II significantly enhanced Arf6 expressions accompanied by increase of Arf6-GTP. The TUNEL-positive cells as well as activated caspase 3, NADPH oxidase 4 protein (Nox4) and ROS levels were dramatically increased in Ang II-treated podocytes, which was prevented by secinH3, an Arf6 activity inhibitor. Induction of ROS by Ang II was inhibited in podocytes with Nox4 knockdown. Ang II-induced elevation of Nox4 and ROS was prevented by Arf6 knockdown. Phpspho-Erk1/2Thr202/Tyr204 levels were upregulated remarkably following Ang II treatment, and Erk inhibitor LY3214996 significantly downregulated Nox4 expression. In addition, Ang II decreased CD2AP expression. Overexpression of CD2AP prevented Ang II-induced upregulation of Arf6-GTP. Our data demonstrated that Ang II promotes ROS production and podocytes injury through activation of Arf6-Erk1/2-Nox4 signaling. We also provided evidence that Ang II activates Arf6 by degradation of CD2AP.
Highlights
Glomerular filtration barrier is composed of endothelial cells, glomerular basement membrane and the slit diaphragm (SD) between foot processes (FPs) of podocytes [1]
Human podocytes were treated with 1 μM of Angiotensin II (Ang II) for 24 h, and indirect immunofluorescence was performed for ADP-ribosylation factor 6 (Arf6) staining
Our data showed that Ang II-induced increase of reactive oxygen species (ROS) production was significantly prevented in human podocytes with stable knockdown of NADPH oxidase 4 protein (Nox4), suggesting that upregulation of Nox4 is responsible for Ang II-induced increase of ROS production
Summary
Glomerular filtration barrier is composed of endothelial cells, glomerular basement membrane and the slit diaphragm (SD) between foot processes (FPs) of podocytes [1]. Podocytes are highly specialized and differentiated glomerular visceral epithelial cells, playing a critical role in the pathogenesis of proteinuria [2]. Several podocyte proteins, such as nephirn, podocin, CD2AP, α-actinin-4, and transient receptor potential cation channel subfamily C member 6 (TRPC6), have been identified and proved to play important role in maintaining normal podocyte function and glomerular filtration barrier [1,2]. Proteinuria, one of the main clinical manifestations in children with nephrotic syndrome, is mainly caused by podocyte injury which can present with disorganization of actin cytoskeleton, FP effacement, loss of the SD, detachment from glomerular basement membrane and cellular apoptosis or death [1,2].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
