The effects of siRNA-silenced TRPC6 on podocyte autophagy and apoptosis induced by AngII

et al. 2018

Cell Physiol Biochem

Background/Aims: Intracellular Ca 2+ signaling plays an important role in the regulation of autophagy. However, very little is known about the role of Ca 2+ influx, which is induced by plasma membrane Ca 2+ channels. Our previous study showed that transient receptor potential canonical channel-6 (TRPC6), a major Ca 2+ influx pathway in podocytes, was activated by hypoxia. Here, we investigated whether TRPC6 is involved in hypoxia-induced autophagy in cultured human podocytes. Methods: In the present study, an immortalized human podocyte cell line was used. Fluo-3 fluorescence was utilized to determine intracellular Ca 2+ concentration ([Ca 2+ ] i ), and western blotting was used to measure autophagy and protein expression. Results: We found that blockade TRPC6 by using either TRPC6 siRNA or a TRPC6 blocker attenuated hypoxia-induced autophagy, while enhancement of TRPC6 activity with a TRPC6 activator enhanced hypoxia-induced autophagy. Furthermore, TRPC6-dependent Ca 2+ signaling is responsible for hypoxia-induced autophagy since both an intracellular and extracellular Ca 2+ chelator abolished hypoxia-induced autophagy. Moreover, we found that blockade of TRPC6 by using either TRPC6 siRNA or a TRPC6 blocker decreased the expression of adenosine monophosphate-activated protein kinase (AMPK), an important signaling molecule in Ca 2+ -dependent autophagy activation, which is activated under hypoxic conditions. These data suggest that the involvement of TRPC6 in hypoxia-induced autophagy is associated with AMPK signaling. Conclusion: TRPC6 is essential for hypoxia-induced autophagy in podocytes.

Section: Discussionsupporting

confidence: 79%

TRPC6-Mediated Ca2+ Signaling is Required for Hypoxia-Induced Autophagy in Human Podocytes

et al. 2018

Cell Physiol Biochem

“…Intriguingly, TRPC6 expression was found to be up-regulated during podocyte apoptosis 20 . More importantly, silencing TRPC6 inhibits AngII-induced apoptosis in podocytes 21 . The TRPC6-encoding mRNA contains a 3'UTR binding site for miR-26a, and the complementary sequence is evolutionarily conserved among the human, chimpanzee, bushbaby, mouse, and rat mRNA orthologs ( Figure 4a ).…”

Section: Resultsmentioning

confidence: 99%

MicroRNA-26a prevents endothelial cell apoptosis by directly targeting TRPC6 in the setting of atherosclerosis

Qin

et al. 2015

Sci Rep

129

Atherosclerosis, a chronic inflammatory disease, is the major cause of life-threatening complications such as myocardial infarction and stroke. Endothelial apoptosis plays a vital role in the initiation and progression of atherosclerotic lesions. Although a subset of microRNAs (miRs) have been identified as critical regulators of atherosclerosis, studies on their participation in endothelial apoptosis in atherosclerosis have been limited. In our study, we found that miR-26a expression was substantially reduced in the aortic intima of ApoE−/− mice fed with a high-fat diet (HFD). Treatment of human aortic endothelial cells (HAECs) with oxidized low-density lipoprotein (ox-LDL) suppressed miR-26a expression. Forced expression of miR-26a inhibited endothelial apoptosis as evidenced by MTT assay and TUNEL staining results. Further analysis identified TRPC6 as a target of miR-26a, and TRPC6 overexpression abolished the anti-apoptotic effect of miR-26a. Moreover, the cytosolic calcium and the mitochondrial apoptotic pathway were found to mediate the beneficial effects of miR-26a on endothelial apoptosis. Taken together, our study reveals a novel role of miR-26a in endothelial apoptosis and indicates a therapeutic potential of miR-26a for atherosclerosis associated with apoptotic cell death.

J Renin Angiotensin Aldosterone Syst

“…19 The in vivo study showed that TRPC6 mutations would eventually cause Ca 2+ dysfunction and result in glomerular disease. [20][21][22] Therefore, we proposed that FK506 can reduce the intracellular calcium overload by inhibiting TRPC6 expression in podocytes, thereby reducing the podocyte apoptosis and stabilizing the number of podocytes, and further protect the podocytes and decrease proteinuria excretion, whereas the specific molecular pathways still need to be verified by related experiments that will be the research direction in the future.…”

Section: Discussionmentioning

confidence: 99%

Influence of tacrolimus on podocyte injury inducted by angiotensin II

Hao

et al. 2015

Self Cite

This study investigated the protective effect of FK506 in podocytes and the correlation of TRPC6 with podocyte injury repair. Methods: MPC5 were cultured in vitro, parallel with the control group, an Ang II stimulation group, and an FK506 intervention group. The apoptosis rate with flow cytometry also detected TRPC6 mRNA and protein expression by RT-PCR and Western blot, and then observed the distribution of TRPC6 with indirect immunofluorescence labeling under confocal microscope. Results: The activities of podocytes significantly increased after FK506 intervention for 24 hours and 48 hours when compared with the Ang II stimulation group, and the apoptosis rate was markedly lower than that of the Ang II stimulation group, while in contrast to TRPC6 mRNA and protein expression. Conclusion: FK506 can directly act on the podocytes to inhibit Ang II-induced damage on podocyte structures and reduce the apoptosis rate of podocytes, which may be related to stabilizing TRPC6 expression and distribution in podocytes by FK506, thus maintaining the structure and function integrity of the slit diaphragm and playing a role in protecting podocytes and antiproteinuria.