Calcium signaling is required for anterior patterning in the mouse embryo

Abstract

Anterior–posterior axis formation in the mouse embryo requires the active migration of the DVE cell population at E5.5. While intracellular Ca2+ signaling has been shown to control cell migration in multiple cell contexts, it is unknown whether it is required for DVE migration. The pattern of Ca2+ activity in the mouse embryo at early peri-implantation stages is also unknown. Using the GCaMP6f Ca2+ reporter line, we performed a detailed assessment of Ca2+ dynamics between E0.5 and E5.5 using live imaging. We find that prior to implantation, Ca2+ transients are rare, but at E5.5 widespread, periodic, Ca2+ transients in extraembryonic tissues can be observed, including in the VE and ExE. In contrast, cells of the E5.5 epiblast remain relatively quiescent but show sporadic large-scale multicellular waves. Inhibition of SERCA at E5.5 abolishes Ca2+ transients and leads to DVE arrest, indicative that these transients are required for axial patterning. Together, these results reveal the pattern of Ca2+ handling in the early mouse embryo and a novel requirement in anterior–posterior axis formation.