L-type voltage-gated Ca channel Ca1.2 regulates chondrogenesis during limb development.

All cells, including nonexcitable cells, maintain a discrete transmembrane potential (), and have the capacity to modulate and respond to their own and neighbors' changes in Spatiotemporal variations have been described in developing embryonic tissues and in some cases have been implicated in influencing developmental processes. Yet, how such changes in are converted into intracellular inputs that in turn regulate developmental gene expression and coordinate patterned tissue formation, has remained elusive. Here we document that the of limb mesenchyme switches from a hyperpolarized to depolarized state during early chondrocyte differentiation. This change in increases intracellular Ca signaling through Ca influx, via Ca1.2, 1 of L-type voltage-gated Ca channels (VGCCs). We find that Ca1.2 activity is essential for chondrogenesis in the developing limbs. Pharmacological inhibition by an L-type VGCC specific blocker, or limb-specific deletion of Ca1.2, down-regulates expression of genes essential for chondrocyte differentiation, including , , and , and thus disturbs proper cartilage formation. The Ca-dependent transcription factor NFATc1, which is a known major transducer of intracellular Ca signaling, partly rescues Sox9 expression. These data reveal instructive roles of Ca1.2 in limb development, and more generally expand our understanding of how modulation of membrane potential is used as a mechanism of developmental regulation.