ALPK1 phosphorylates myosin IIA modulating TNF-α trafficking in gout flares.

Chi-Pin Lee,Eing-Mei Tsai,Che Ma,Yu-Fan Liu,Chi-Yu Lu,Shang-Lun Chiang,Tzer-Min Kuo,Jan-Gowth Chang,Ying-Chin Ko,Chung-Ming Huang,Albert Min-Shan Ko,Chia-Lin Chen

doi:10.1038/srep25740

Abstract

Gout is characterized by the monosodium urate monohydrate (MSU)-induced arthritis. Alpha kinase-1 (ALPK1) has shown to be associated with MSU-induced inflammation and gout. Here, we used bioinformatics, proteomics, cell models, and twenty in vitro human assays to clarify some of its role in the inflammatory response to MSU. We found myosin IIA to be a frequent interacting protein partner of ALPK1, binding to its N-terminal and forming a protein complex with calmodulin and F-actin, and that MSU-induced ALPK1 phosphorylated the myosin IIA. A knockdown of endogenous ALPK1 or myosin IIA significantly reduced the MSU-induced secretion of tumour necrosis factor (TNF)-α. Furthermore, all gouty patients expressed higher basal protein levels of ALPK1, myosin IIA, and plasma TNF-α, however those medicated with colchicine has shown reduced myosin IIA and TNF-α but not ALPK1. The findings suggest ALPK1 is a kinase that participates in the regulation of Golgi-derived TNF-α trafficking through myosin IIA phosphorylation in the inflammation of gout. This novel pathway could be blocked at the level of myosin by colchicine in gout treatment.

Highlights

We previously showed an association for gout in chromosome 4q25 region (OMIM #138900; gout susceptibility 1) using genome-wide familial linkage on ethnic aboriginal Taiwanese known for a high prevalence of tophaceous gout[1]
We compared Alpha kinase-1 (ALPK1) to myosin light-chain kinase (MLCK), a known serine/ threonine-specific protein kinase that phosphorylates the regulatory light chain of myosin II, we found no change to the tumour necrosis factor (TNF)-αsecretion after MLCK knockdown in THP-1 cells for 24-h prior to monosodium urate (MSU) treatment (100 μg/ mL; Fig. 5D)
We found ALPK1 phosphorylation of non-muscle myosin IIA was relatively specific for the MSU-induced secretion of TNF-α

Summary

Introduction

We previously showed an association for gout in chromosome 4q25 region (OMIM #138900; gout susceptibility 1) using genome-wide familial linkage on ethnic aboriginal Taiwanese known for a high prevalence of tophaceous gout[1]. ALPK1 has shown to be expressed alongside proinflammatory cytokines, such as tumour necrosis factor (TNF)-αand interleukin (IL)-1β, via activation of ERK1/2 and p38 in monosodium urate (MSU)-induced human monocytic THP-1 cells[3], the understanding of biological role of ALPK1 in gouty inflammation remains unclear. ALPK1 is known to phosphorylate the tail region of Dictyostelium discoideum myosin II5 and is implicated in raft-associated sucrase–isomaltase of epithelial cells by phosphorylating the motor protein myosin I that mediates a sorting process via exocytic transport to the apical plasma membrane[6]. We sought to investigate the ALPK1 protein-binding partners, their interactions, and determine whether cytokine secretion has any mediating effects through phosphorylated myosin in MSU-induced monocytes.

Methods

Results

Conclusion