Inhibition of TRPC6 Signal Pathway Alleviates Podocyte Injury Induced by TGF-β1

Abstract

Background/Aims: Transforming growth factor beta 1 (TGF-β1) plays a critical role in the pathogenesis of glomerulosclerosis. The purpose of this study was to examine the effects of inhibition of transient receptor potential cation channel C6 (TRPC6) on podocyte injury induced by TGF-β1 via nephrin and desmin mechanisms. Methods: A rat model of nephropathy was first induced by intravenous injections of adriamycin to determine TRPC6 signal pathway engaged in glomerulosclerosis in vivo. Conditionally immortalized podocytes were cultured in vitro and they were divided into four groups: control; TGF-β1 treatment; TGF-β1 with TRPC6 knockdown and TGF-β1 without TRPC6 knockdown. Real time RT-PCR and Western blot analysis were employed to determine the mRNA and protein of expression of nephrin, desmin and caspase-9, respectively. Flow cytometry was used to examine the apoptotic rate of podocytes and DAPI fluorescent staining was used to determine apoptotic morphology. Results: In vivo experiment, adriamycin significantly upregulated the protein expression of TGF-β1, TRPC6, desmin and caspase-9, and decreased nephrin. Consistent with the latter results, in vitro experiment mRNA and protein expression of desmin and caspase-9 was increased in cultured TGF-β1-treated podocytes, whereas nephrin was declined as compared with the control group. Importantly, TRPC6 knockdown significantly attenuated the upregulated desmin and caspase-9, and alleviated impairment of nephrin induced by TGF-β1. Moreover, typical morphologic features were presented in apoptotic podocytes. The number of apoptotic podocytes was increased after exposure to TGF-β1 and this was alleviated after TRPC6 knockdown. TRPC6 knockdown also decreased an apoptosis rate of TGF-β1-treated podocytes. Note that negative TRPC6 transfection control failed to alter an increase of the apoptosis rate in TGF-β1-treated podocytes. Conclusions: TGF-β1 induced by glomerulosclerosis impairs the protein expression of nephrin and amplifies the protein expression of desmin and caspase -9 via TRPC6 signal pathway. Inhibition of TRPC6 alleviates these changes in podocytes-treated with TGF-β1 and attenuated apoptosis of podocytes. Our data suggest that TRPC6 signal plays an important role in mediating TGF-β1-induced podocyte injury via nephrin, desmin and caspase-9. Results of the current study also indicate that blocking TRPC6 signal pathway has a protective effect on podocyte injury. Targeting one or more of these signaling molecules may present new opportunities for treatment and management of podocyte injury observed in glomerulosclerosis.

Role of MiR-155 Signal Pathway in Regulating Podocyte Injury Induced by TGF-β1

“…Our recent work has shown that nephrin is decreased whereas desmin is upregulated in injured podocyte induced by TGF-β1 [19], indicating that nephrin and desmin are involved in TGF-β1-induced podocyte injuries. Additionally, miR-155 is specifically localized in renal tissues and engaged in the pathogenesis of renal symptoms in patients with glomerulonephritis [26, 27].…”

“…in involvement of podocyte injury induced by TGF-β1 [16-18]. It should be noted that using a rat model with systemic injection of ADR, our recent study consistently observed that the higher protein expression levels of TGF-β1and apoptotic Caspase-9 in glomerular tissues, suggesting the role of TGF-β1 in the process of FSGS [19]. Nonetheless, it is significant to further determine the mechanisms leading to FSGS in renal diseases by using ADR-induced nephropathy.…”

TRPC 6 as a Molecular Target in Diabetic Nephropathy

“…TRPC6 signal plays a key role in mediating TGF-β1 induced podocyte injury via nephrin, desmin and caspase-9. [14] Pathway: GPCRs coupled to Gq signaling activate TRPC6, proposing that Gq-dependent TRPC6 stimulation underlies glomerular diseases [15] . Wnt/β-catenin signalling pathway may possibly be dynamic in pathogenesis of TRPC6-mediated diabetic podocyte injury [10] .…”

“…AS-IV may check HG-induced podocyte apoptosis via down regulation of TRPC6, which is maybe mediated via the calcineurin/NFAT signaling pathway [11] . Blockade of Wnt/β-catenin signalling by paricalcitol ameliorates proteinuria and kidney injury [18] Gq/TRPC6 signalling may have therapeutic benefits for the treatment of glomerular diseases [15] . Blocking TRPC6 signal pathway has a protective effect on podocyte injury [14] .…”

Rapamycin Reduces Podocyte Apoptosis and is Involved in Autophagy and mTOR/ P70S6K/4EBP1 Signaling

“…Thus, an impairment of any of their barrier functions following podocyte injury results in severe proteinuria and renal failure. Moreover, prolonged podocyte injury leads to glomerulosclerosis and progression of kidney disease [1][2][3][4][5]; however, the physiological regulation of podocytes and the pathological processes following injury are currently unclear.…”