ATP promotes resident CD34+ cell migration mainly through P2Y2-Stim1-ERK/p38 pathway

Extracellular adenosine triphosphate (ATP) is one of the most abundant biochemical constitutes within the stem cell microenvironment and is postulated to play critical roles in cell migration. However, it is unclear whether ATP regulates the cell migration of CD34⁺ vascular wall-resident stem/progenitor cells (VW-SCs) and participates in angiogenesis. Therefore, the biological mechanisms of cell migration mediated by ATP was determined by in vivo subcutaneous matrigel plug assay, ex vivo aortic ring assay, in vitro transwell migration assay and other molecular methods. In present study, ATP dose-dependently promoted CD34⁺ VW-SCs migration, which were more obviously attenuated by inhibition or knocking down P2Y2 than P2Y6. Furthermore, it was confirmed that ATP potently promoted the migration of resident CD34⁺ cells from cultured aortic artery rings and differentiation into endothelial cells in matrigel plugs by using inducible lineage tracing CD34-CreER^T2; R26-tdTomato mice, while P2Y2 and P2Y6 blocker greatly inhibited the effect of ATP. Additionally, ATP enhanced the membrane protein expression of Stromal Interaction Molecule 1 (STIM1), blocking CRAC Channel with shSTIM1or BTP2 apparently inhibited ATP evoked intracellular Ca²⁺ elevation and channel opening, thereby suppressed ATP-driven cell migration. Moreover, extracellular signal regulated protein kinase (ERK) inhibitor PD98059, p38 inhibitor SB203580 remarkably inhibited ERK and P38 phosphorylation, Cytoskeleton rearrangement and subsequent cell migration. Interesting, it was unexpectedly to find that knocking down STIM1 greatly inhibited ATP triggered ERK/p38 activation. Taken together, it was suggested that P2Y2 signaled through CRAC Channel mediated Ca²⁺ influx and ERK/p38 pathway to reorganize Cytoskeleton and promoted the migration of CD34⁺ VW-SCs.

Adenosine triphosphate; MAPK pathway; Stim1; purinergic receptor; resident vascular wall CD34+ cells.