Erk5 is a mediator to TGFβ1-induced loss of phenotype and function in human podocytes

Abstract

Background: Podocytes are highly specialized cells integral to the normal functioning kidney, however, in diabetic nephropathy injury occurs leading to a compromised phenotype and podocyte dysfunction which critically produces podocyte loss with subsequent renal impairment. TGFβ1 holds a major role in the development of diabetic nephropathy. Erk5 is an atypical mitogen-activated protein (MAP) kinase involved in pathways modulating cell survival, proliferation, differentiation, and motility. Accordingly, the role of Erk5 in mediating TGFβ1-induced podocyte damage was investigated.Methods: Conditionally immortalized human podocytes were stimulated with TGFβ1 (2.5 ng/ml); inhibition of Erk5 activation was conducted with the chemical inhibitor BIX02188 (10 μM) directed to the upstream Mek5; inhibition of Alk5 was performed with SB431542 (10 μM); Ras signaling was inhibited with farnesylthiosalicylic acid (10 μM). Intracellular signaling proteins were investigated by western blotting; phenotype was explored by immunofluorescence; proliferation was assessed with a MTS assay; motility was examined with a scratch assay; barrier function was studied using electric cell-substrate impedance sensing; apoptosis was studied with annexin V-FITC flow cytometry.Results: Podocytes expressed Erk5 which was phosphorylated by TGFβ1 via Mek5, whilst not involving Ras. TGFβ1 altered podocyte phenotype by decreasing P-cadherin staining and increasing α-SMA, as well as reducing podocyte barrier function; both were prevented by inhibiting Erk5 phosphorylation with BIX02188. TGFβ1-induced podocyte proliferation was prevented by BIX02188, whereas the induced apoptosis was not. Podocyte motility was reduced by BIX02188 alone and further diminished with TGFβ1 co-incubation.Conclusion: These results describe for the first time the expression of Erk5 in podocytes and identify it as a potential target for the treatment of diabetic renal disease.

Combination of glycopyrronium and indacaterol inhibits carbachol-induced ERK5 signal in fibrotic processes

“…García-Hoz et al revealed that CCh induces the formation of Gαq/protein kinase C (PKC) ζ and MEK5 protein complexes to trigger ERK5 activation in mouse embryonic fibroblasts [ 35 ]. Badshah et al reported that TGF-β1 mediates ERK5 activation in human podocytes without the involvement of the small GTPase Ras [ 36 ]. In the present study, CCh and TGF-β1 induced ERK5 phosphorylation in lung fibroblasts, and BIX02189 attenuated CCh- or TGF-β1-induced gel contraction and α-SMA expression.…”

Protein kinases: mechanisms and downstream targets in inflammation-mediated obesity and insulin resistance

“…The deletion of ERK5 increased adiposity with dysregulation in adipokines secretion, leptin resistance, and impaired glucose handling [116]. It has been identified that above effect of ERK5 in diabetic nephropathy is mediated by TGFβ1 induced phosphorylation of MEK5 without involvement of the MAP3K Ras [117]. There are no extensive studies on ERK3, ERK4 and ERK7, hence there is a need to study their role in insulin resistance.…”

ERK5 plays an essential role in gestational beta‐cell proliferation

“…Among all signalling molecules, MAPKs are factors that are connected to different pathways. As a focus of this study, ERK5 can be activated through NGF and its receptor TrkA at the nerve terminal, or be activated through G‐CSF/G‐CSF receptor in the regulation of granulopoiesis, or be activated through TGF‐beta/TGF‐beta receptor in the control of function and survival of podocytes . However, the association of ERK5 with Hsp90 and Cdc37 super‐chaperone renders ERK5 a regulator of other signalling pathways that include Hsp90 or Cdc37 as involved molecules .…”