Netrin-1-Induced Stem Cell Bioactivity Contributes to the Regeneration of Injured Tissues via the Lipid Raft-Dependent Integrin α6β4 Signaling Pathway.

Soo Sang Lee,Young Hyun Jung,Jun Sung Kim,Jung Min Ryu,Sei-Jung Lee,Ho Jae Han,Chung Hun Kim,Sang Hun Lee,Hyun Jik Lee,Hyeon Su Lim,Eun Ju Song

doi:10.1038/srep37526

Abstract

Netrin-1 (Ntn-1) is a multifunctional neuronal signaling molecule; however, its physiological significance, which improves the tissue-regeneration capacity of stem cells, has not been characterized. In the present study, we investigate the mechanism by which Ntn-1 promotes the proliferation of hUCB-MSCs with regard to the regeneration of injured tissues. We found that Ntn-1 induces the proliferation of hUCB-MSCs mainly via Inα6β4 coupled with c-Src. Ntn-1 induced the recruitment of NADPH oxidases and Rac1 into membrane lipid rafts to facilitate ROS production. The Inα6β4 signaling of Ntn-1 through ROS production is uniquely mediated by the activation of SP1 for cell cycle progression and the transcriptional occupancy of SP1 on the VEGF promoter. Moreover, Ntn-1 has the ability to induce the F-actin reorganization of hUCB-MSCs via the Inα6β4 signaling pathway. In an in vivo model, transplantation of hUCB-MSCs pre-treated with Ntn-1 enhanced the skin wound healing process, where relatively more angiogenesis was detected. The potential effect of Ntn-1 on angiogenesis is further verified by the mouse hindlimb ischemia model, where the pre-activation of hUCB-MSCs with Ntn-1 significantly improved vascular regeneration. These results demonstrate that Ntn-1 plays an important role in the tissue regeneration process of hUCB-MSC via the lipid raft-mediated Inα6β4 signaling pathway.

Highlights

Netrin-1 (Ntn-1), a diffusible neural guidance protein, is a bifunctional signaling molecule related to cell proliferation, cell migration, and cell-extracellular matrix adhesion during the neuronal development process[7,8]
In the present study we showed that Ntn-1 has the ability to induce stem cell proliferation via the distinct lipid raft-dependent Inα6β4 signaling pathway, which plays a critical role in the governing of vascular endothelial growth factor (VEGF) induction and the cytoskeletal reorganization of human umbilical-cord-blood-derived (hUCB)-mesenchymal stem cells (MSCs)
Concerning the cellular mechanisms of Ntn-1 with regard to amplifying the level of stem cell bioactivity, we showed a unique relationship between the lipid raft-dependent Inα6β4 signaling pathway and reactive oxygen species (ROS) production in the regulation of hUCB-MSC proliferation

Summary

Introduction

Netrin-1 (Ntn-1), a diffusible neural guidance protein, is a bifunctional signaling molecule related to cell proliferation, cell migration, and cell-extracellular matrix adhesion during the neuronal development process[7,8]. The Ntn-1 signaling pathway in non-neuronal tissue has received little attention, many netrin receptors have been detected, in the nervous system[7,9], and in a number of other tissues[8,10], where their functions remain largely unknown. Despite the fact that Ntn-1 has attracted much attention regarding its potential in cell proliferation and tissue regeneration capacities[10,13,14,15], the underlying cellular mechanisms of Ntn-1, which improves the bioactivity of stem cells during the tissue regeneration process, remain largely unknown. We investigate the mechanism of the Ntn-1 signaling pathway in promoting the bioactivity of hUCB-MSCs with regard to the regeneration of injured tissues

Methods

Results

Conclusion