Integrin-mediated Membrane Blebbing Is Dependent on Sodium-Proton Exchanger 1 and Sodium-Calcium Exchanger 1 Activity

Yung-Hsiang Yi,Yu-Sun Chang,Chi-Hung Lin,Tien-Shen Lew,Chih-Yung Tang,Wei-Lien Tseng,Ching-Ping Tseng,Szecheng J Lo

doi:10.1074/jbc.m111.244962

Abstract

Integrin signaling and membrane blebbing modulate cell adhesion, spreading, and migration. However, the relationship between integrin signaling and membrane blebbing is unclear. Here, we show that an integrin-ligand interaction induces both membrane blebbing and changes in membrane permeability. Sodium-proton exchanger 1 (NHE1) and sodium-calcium exchanger 1 (NCX1) are membrane proteins located on the bleb membrane. Inhibition of NHE1 disrupts membrane blebbing and decreases changes in membrane permeability. However, inhibition of NCX1 enhances cell blebbing; cells become swollen because of NHE1 induced intracellular sodium accumulation. Our study found that NHE1 induced sodium influx is a driving force for membrane bleb growth, while sodium efflux (and calcium influx) induced by NCX1 in a reverse mode results in membrane bleb retraction. Together, these findings reveal a novel function for NHE1 and NCX1 in membrane blebbing and permeability, and establish a link between membrane blebbing and integrin signaling.

Highlights

Integrin signaling and membrane blebbing modulate cell adhesion and migration, the link between them is unknown
Nor did we observe any change in membrane permeability when parental CHO cells and CHO cells expressing integrin␣v␤3 were plated onto the rhodostomin (RGD)-coated substrate (Fig. 1C)
Our observations show that integrin␣IIb␤3 signals, which mediate cell spreading, induce membrane blebbing in CHO␣IIb␤3 cells (Fig. 2A)

Summary

Background

Integrin signaling and membrane blebbing modulate cell adhesion and migration, the link between them is unknown. Our study found that NHE1 induced sodium influx is a driving force for membrane bleb growth, while sodium efflux (and calcium influx) induced by NCX1 in a reverse mode results in membrane bleb retraction Together, these findings reveal a novel function for NHE1 and NCX1 in membrane blebbing and permeability, and establish a link between membrane blebbing and integrin signaling. NHE1 and NCX1 both appear in homodimeric forms and are functionally coupled; NHE1 drives sodium ion influx, which in turn activates NCX1 in a reverse mode to generate a calcium influx and modulate intracellular calcium oscillations [15, 17,18,19,20] It is not clear if integrin signaling generally triggers ion transport. We recorded cell membrane activity by time-lapse microscopy to observed membrane blebbing

EXPERIMENTAL PROCEDURES

RESULTS

DISCUSSION