TRPV3 Channels Mediate Strontium-Induced Mouse-Egg Activation

In mammals, calcium influx is required for oocyte maturation and egg activation. The molecular identities of the calcium-permeant channels that underlie the initiation of embryonic development are not established. Here, we describe a transient receptor potential (TRP) ion channel current activated by TRP agonists that is absent in TrpV3−/− eggs. TRPV3 current is differentially expressed during oocyte maturation, reaching a peak of maximum density and activity at metaphase of meiosis II (MII), the stage of fertilization. Selective activation of TRPV3 channels provokes egg activation by mediating massive calcium entry. Widely used to activate eggs, strontium application is known to yield normal offspring in combination with somatic cell nuclear transfer. We show that TRPV3 is required for strontium influx, because TrpV3−/− eggs failed to conduct Sr2+ or undergo strontium-induced activation. We propose that TRPV3 is a major mediator of calcium influx in mouse eggs and is a putative target for artificial egg activation. [Display omitted] •TRPV3 channels are functionally expressed in mouse oocytes and eggs•TRPV3 channels are progressively expressed during oocyte maturation•TRPV3 channels can mediate Ca2+ influx and parthenogenesis in MII eggs•Strontium influx and subsequent egg activation in mice require TRPV3 channels The calcium-permeant channels in mammalian eggs that underlie maturation and the initial steps after fertilization are not known. Here, Clapham and colleagues show that the transient receptor potential (TRP) TRPV3 channel is functional in mouse eggs. Selective TRPV3 activation mediates massive calcium entry and provokes egg parthenogenesis. TRPV3 channels mediate the strontium influx used in artificial egg activation, because TrpV3−/− eggs fail to conduct strontium or undergo strontium-induced activation. TRPV3 is the major calcium entry pathway in mouse eggs.