ABSTRACT Store operated Ca 2+ entry (SOCE) is altered in neonatal platelets with respect to adult platelets. Here, we aim to analyze the changes in STIMATE translation that leads to generating STIMATE‐mustn1 and its possible involvement in SOCE in neonatal platelets. As a result, we have found different expression patterns of STIMATE, mustn1 and STIMATE‐mustn1 in platelets isolated from mothers with respect to their newborns. Calcium (Ca 2+ ) experiments using MEG‐01 cells overexpressing STIMATE or the fused protein STIMATE‐mustn1 reveal that mustn1 binding to STIMATE impairs its role in SOCE; meanwhile, overexpression of mustn1 alone does not alter SOCE. Confocal images of MEG‐01 and HEK293 cells reveal that the alteration in the expression of STIMATE modifies the co‐localization between Orai1 and STIM1. Furthermore, STIMATE or STIMATE‐mustn1 overexpression exhibits different intracellular location patterns, which were also different when compared between MEG‐01 and HEK293 cells. Finally, STIMATE overexpression arrests the cell cycle of MEG‐01 cells in the G2 phase, which represents a key step during the maturation of MEG‐01 cells, but STIMATE‐mustn1 overexpression does not change the cell cycle of MEG‐01. Summarizing, we propose that overexpression of STIMATE‐mustn1 by neonatal platelets might be an attempt to limit the exacerbated activation of SOCE found in these platelets.
Berna‐Erro et al. (Thu,) studied this question.