The role of inositol 1,4,5 -trisphosphate receptor type-1 in regulation of intracellular calcium oscillations in mouse eggs
Calcium ([Ca2+]i) oscillations, a hallmark of mammalian fertilization, are essential to induce egg activation and embryonic development. As the zygotes transition through the cell cycle, these [Ca 2+]i oscillations progressively diminish until they cease in interphase zygotes. While the mechanism(s) underlying the regulation of [Ca2+]i oscillations may be multi-layered, inositol 1,4,5-trisphosphate receptors (IP3Rs) emerge as a focal point in this regulation. IP3Rs, the calcium channels expressed in all cell types and abundantly expressed in mammalian eggs, contain consensus sequences for phosphorylation by various kinases and interact with members of the cytoskeleton, serving as an integrator of regulatory signals. This dissertation highlights the impact of biochemical and cellular changes in IP3R-1 on fertilization-induced [Ca2+]i oscillations. Together with the changes in the cellular distribution of the sperm factor, these cell cycle-dependent modifications in IP3R-1 may underlie the regulation of [Ca 2+]i oscillations in fertilized mammalian eggs.