ATP purinergic receptor signalling promotes Sca-1 cell proliferation and migration for vascular remodelling.

AIMS

Vascular resident stem cells expressing stem cell antigen-1 (Sca-1 cells) promote vascular regeneration and remodelling following injury through migration, proliferation and differentiation. The aim of this study was to examine the contributions of ATP signalling through purinergic receptor type 2 (P2R) isoforms in promoting Sca-1 cell migration and proliferation after vascular injury and to elucidate the main downstream signalling pathways.

METHODS AND RESULTS

ATP-evoked changes in isolated Sca-1 cell migration were examined by transwell assays, proliferation by viable cell counting assays and intracellular Ca signalling by fluorometry, while receptor subtype contributions and downstream signals were examined by pharmacological or genetic inhibition, immunofluorescence, Western blotting and quantitative RT-PCR. These mechanisms were further examined in mice harbouring TdTomato-labelled Sca-1 cells with and without Sca-1-targeted P2R knockout following femoral artery guidewire injury. Stimulation with ATP promoted cultured Sca-1 cell migration, induced intracellular free calcium elevations primarily via P2YR stimulation and accelerated proliferation mainly via P2YR stimulation. Enhanced migration was inhibited by the ERK blocker PD98059 or P2YR-shRNA, while enhanced proliferation was inhibited by the P38 inhibitor SB203580. Femoral artery guidewire injury of the neointima increased the number of TdTomato-labelled Sca-1 cells, neointimal area and the ratio of neointimal area to media area at 3 weeks post-injury, and all of these responses were reduced by P2YR knockdown.

CONCLUSIONS

ATP induces Sca-1 cell migration through the P2YR-Ca-ERK signalling pathway, and enhances proliferation through the P2YR-P38-MAPK signalling pathway. Both pathways are essential for vascular remodelling following injury. Video Abstract.