Syndecan-4 Shedding Involved In Impaired Homing Of Endothelial Progenitor Cell In Diabetes Mellitus And The Preliminary Research On Treatment Of Resveratrol In Vitro

Background and ObjectiveMigration of endothelial progenitor cells(EPC)is impaired in diabetic patients,which leads to worse myocardial recovery following cardiovascular diseases.Stromal cell derived factor 1(SDF-1)is the most important chemokine in EPC homing,and several lines of evidence have indicated that SDF-1 could exert its effects via syndecan-4(Synd4)besides of its classic receptor CXCR4.Synd4 shedding has been showed to affect cellular functions in many pathological conditions.Thus,in the present study,we focused the effect of Synd4 shedding induced by oxidative stress on EPC homing in diabetic mellitus,at the same time,we observed the effect of resveratrol on Syn4 shedding from EPC membrane in vitro.Methods14 weeks after T1-DM rats induced by STZ were established,we isolated and cultured bone marrow-derived EPCs,and then investigated the Synd4 shedding and ROS levels.After identification of cultured EPCs derived from human peripheral blood,EPCs were treated with AGEs,NAC(an antioxidant),anti-RAGE(a neutralizing antibody of RAGE),Glycyrrhizin(an inhibitor of HMGB1),we investigated the mechanism of Synd4 shedding using western,immunofluorescence and enzyme dynamic assays.In addition,RNA interference using lentivirus as a vector was proceeded to investigate the effect of Synd4 shedding on the migration of EPC induced by SDF-1 and on Akt/eNOS pathway.After labeled with CM-Dil,wild type(WT)and Synd4-/-MNCs isolated from mice bone marrow were transplanted into hind limb ischemia models via tail vein,then we detected the homing cells using fluorescence microscope and angiogenesis using immunofluorescence.After pretreated with resveratrol or/and Ex527,human EPCs were incubated with AGEs,then we investigated the role of sirtl in underlying mechanism of Synd4 shedding by western blot and immunofluorescence.ResultsIn diabetic mellitus,AGEs and HMGB1 both triggered ROS generation through binding to RAGE,and the upregulated ROS level stimulated Synd4 shedding from EPC membrane.In vitra assay,Synd4 shedding played an important role in impaired EPC migration.Compared with wide type cells,Synd4-/-cells showed dysfunction of homing to the ischemia hind limb tissue as well as angeiogenesis.In addition,Akt/eNOS mediated the migration of EPC as a downstream of Synd4.Resveratrol attenuated Synd4 shedding from EPC membrane induced by oxidative stress via sirtl in vitro.conclusionSynd4 shedding induced by oxidative stress is involved in EPC homing in diabetic mellitus,and resveratrol can suppress Synd4 shedding induced by oxidative stress via upregulation of sirtl.