BAFF attenuates oxidative stress-induced cell death by the regulation of mitochondria membrane potential via Syk activation in WiL2-NS B lymphoblasts

Sojin Park,Ju-Won Jang,Eun-Yi Moon

doi:10.1038/s41598-020-68628-5

Abstract

Cell survival is facilitated by the maintenance of mitochondrial membrane potential (MMP). B cell activating factor (BAFF) plays a role in survival, differentiation, and maturation of B cells. In the present study, we examined whether BAFF could attenuate oxidative stress-induced B cell death by the regulation of MMP collapse via spleen tyrosine kinase (Syk) activation using WiL2-NS human B lymphoblast cells. BAFF binds to receptors on WiL2-NS cells. When the cells were incubated in serum-deprived conditions with 1% fetal bovine serum (FBS), BAFF reduced the percentage of dead cells as determined through trypan blue staining and caspase 3 activity. BAFF also inhibited MMP collapse with 1% FBS, as indicated by a decrease in the number of cells with high-red fluorescence of MitoProbe™ JC-1 reagent or a decrease in the percentage of DiOC6-stained cells. Reactive oxygen species (ROS) production was reduced by incubation with BAFF in the presence of 10% or 1% FBS. BAFF inhibited MMP collapse, cell growth retardation, dead cell formation, and caspase 3 activation caused by treatment with H2O2. Syk phosphorylation on tyrosine (Y) 525/526 was increased in cells incubated with 1% FBS in the presence of BAFF than cells incubated with 1% FBS or BAFF alone. BAY61-3606, a Syk inhibitor reduced the effect of BAFF on MMP collapse, caspase 3 activation, cell growth retardation, and dead cell formation. Together, these data demonstrate that BAFF might attenuate oxidative stress-induced B cell death and growth retardation by the maintenance of MMP through Syk activation by Y525/526 phosphorylation. Therefore, BAFF and Syk might be therapeutic targets in the pathogenesis of B cell-associated diseases such as autoimmune disease.

Highlights

B cell activating factor (BAFF), known as TALL-1, BLyS, THANK, and TNFSF13B, belongs to the tumor necrosis factor (TNF) superfamily[1]
No B cell maturation antigen (BCMA) expression was detected, which suggests that BAFF might affect WiL2-NS cells via BAFF binding on the cell surface
B cells play a role in the progression of autoimmune disease by releasing inflammatory cytokines, presenting autoantigens, producing antibodies, and ensuring interactions with T c ells[43]

Summary

Introduction

B cell activating factor (BAFF), known as TALL-1, BLyS, THANK, and TNFSF13B, belongs to the tumor necrosis factor (TNF) superfamily[1]. Little is known about the effects of BAFF on MMP by ROS production via Syk in human B cells. Oxidative stress-induced Syk activation activates different pathways, such as pro-apoptotic and survival pathways. A balance of pro-apoptotic and survival pathways are important for determining the fate of cells exposed to oxidative stress[13]. Syk expression protects cells from apoptosis induced by oxidative or genotoxic stress in MCF7 and MDA-MB-231 breast cancer cells and DG75 B-lymphoma cells[32]. Syk-dependent PLC-gamma[2] activation was required for acceleration towards apoptosis following oxidative stress[13]. These reports from different groups yielded contradictory results, so it is necessary to clarify the connection between BAFF signaling and Syk phosphorylation in B cells

Methods

Results

Conclusion