Platelet-derived microvesicles drive vascular smooth muscle cell migration via forming podosomes and promoting matrix metalloproteinase-9 activity

We have shown that platelet-derived microvesicles(PMVs)induce abnormal proliferation,migration,and energy metabolism of vascular smooth muscle cells(VSMCs)after vascular intimal injury.Here,we examined a novel role of podosome in mediating matrix metalloproteinase-9(MMP-9)dependent VSMC migration induced by plateletderived microvesicles(PMVs).VSMCs were isolated from the thoracic aortas of male Sprague Dawley(SD)rats and identified with immunofluorescent staining.Blood samples were collected from SD Rats,the platelets were isolated with density gradient centrifugation from the blood samples and activated by collagen I.Intriguingly,proteins expressed in platelets were found to participate in the positive regulation of podosome assembly using GO analysis by DAVID,and most of the proteins were found in extracellular exosomes.Of note,activated platelets indirectly induced VSMC migration via releasing PMVs which was verified using platelets and VSMCs transwell coculture system.Besides,podosome,an invasive protrusion to mediate extracellular matrix(ECM)remodeling,was formed in VSMCs to induce cell migration.Furthermore,MMP-9 activity detected by gelatin zymography was used to verify the function of the podosome in ECM remodeling.The result indicated that MMP-9 activity was robustly activated in VSMCs to implement the function of the podosome.In addition,gelatin degradation was detected in intact VSMCs using a gelatin degradation assay after co-culture with platelets.Taken together,our data reveal a novel mechanism that PMVs promote VSMC migration via forming podosomes and inducing MMP-9 activity.

A key role for PTP1B in dendritic cell maturation, migration, and T cell activation

Dendritic cells(DC)are the major antigen-presenting cells bridging innate and adaptive immunity,a function they perform by converting quiescent DC to active,mature DC with the capacity to activate naı¨ve T cells.They do this by migrating from the tissues to the T cell area of the secondary lymphoid tissues.Here,wedemonstrate thatmyeloid cell-specific genetic deletion of PTP1B(LysM PTP1B)leads to defects in lipopolysaccharide-driven bone marrow-derivedDC(BMDC)activation associated with increased levels of phosphorylated Stat3.We showthatmyeloid cell-specific PTP1Bdeletion also causes decreased migratory capacity of epidermal DC,aswell as reduced CCR7 expression and chemotaxis to CCL19 by BMDC.PTP1B deficiency in BMDC also impairs their migration in vivo.Further,immature LysM PTP1B BMDC display fewer podosomes,increased levels of phosphorylated Src at tyrosine 527,and loss of Src localization to podosome puncta.In co-culture with T cells,LysM PTP1B BMDC establish fewer and shorter contacts than control BMDC.Finally,LysMPTP1BBMDCfail to present antigen to T cells as efficiently as controlBMDC.These data provide first evidence for a key regulatory role for PTP1B in mediating a central DC function of initiating adaptive immune responses in response to innate immune cell activation.