Regulation of cofilin phosphorylation in glomerular podocytes by testis specific kinase 1 (TESK1)

Liming Wang,Robert F Spurney,Anne F Buckley

doi:10.1038/s41598-018-30115-3

Liming Wang, Robert F Spurney + Show 1 more

Open Access

https://doi.org/10.1038/s41598-018-30115-3

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Abstract

Expression of a constitutively active Rho A (V14Rho) in podocytes in vivo induces albuminuria and foot process (FP) effacement. These effects may be mediated by the Rho A effector Rho kinase (ROK); but inhibition of ROK with Y27632 failed to attenuate albuminuria or FP effacement in V14Rho mice. ROK activates LIM kinases (LIMKs), which phosphorylate and inhibit the actin depolymerizing factor cofilin 1 (CFL1). Sustained phosphorylation of CFL1 is implicated in human nephrotic diseases, but Y27632 did not inhibit phosphorylation of CFL1 in vivo, despite effective ROK inhibition. CFL1 is also phosphorylated by testis-specific kinase 1 (TESK1) on the same serine residue. TESK1 was expressed in podocytes, and, similar to the in vivo situation, Y27632 had little effect on phospho-CFL1 (pCFL1) levels in cultured podocytes. In contrast, Y27632 reduced pCFL1 levels in TESK1 knockout (KO) cells. ROK inhibition enhanced podocyte motility but, the motility promoting effect of Y27632 was absent in TESK1 KO podocytes. Thus, TESK1 regulates podocyte cytoskeletal dynamics in glomerular podocytes and may play an important role in regulating glomerular filtration barrier integrity in glomerular disease processes.

Highlights

Glomerular podocytes are highly differentiated cells that cover the external surface of the glomerular blood vessels, and maintain the structural and functional integrity of the kidney’s glomerular filter[1]
We found that albuminuria and foot process (FP) effacement in V14Rho mice were not affected by treatment with the Rho kinase (ROK) inhibitor Y27632
Because cofilin 1 (CFL1) is phosphorylated by TESK123 on the same serine residue as ROK-LIM kinases (LIMKs) signaling, we determined if testis-specific kinase 1 (TESK1) contributed to CFL1 regulation in podocytes

Summary

Introduction

Glomerular podocytes are highly differentiated cells that cover the external surface of the glomerular blood vessels, and maintain the structural and functional integrity of the kidney’s glomerular filter[1]. These small GTPases act as molecular switches controlling activation of multiple downstream effector molecules[5,6,7,8] Among their pleiotropic actions, Rho-dependent signaling cascades modulate cellular morphology and actin polymerization, adhesion, cell migration, proliferation and apoptosis as well as participate in contractile responses[5,6,7,8]. The inability of Y27632 to reduce albuminuria did not appear to result from an ineffective dosage of Y27632, but was associated with sustained phosphorylation of the actin-depolymerizing factor CFL1 on serine 3, a downstream target of ROK signaling[20] This may have implications for proteinuric kidney diseases because pCFL1 inhibits its actin-depolymerizing activity[20], and CFL1 deficiency promotes proteinuria in animal models[21]. Our findings suggest an important role for TESK1 in regulating the podocyte actin cytoskeleton

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