L-type voltage-gated Ca²⁺ channel Ca_V1.2 regulates chondrogenesis during limb development.

Abstract

All cells, including nonexcitable cells, maintain a discrete transmembrane potential (<i>V</i>_mem), and have the capacity to modulate <i>V</i>_mem and respond to their own and neighbors' changes in <i>V</i>_mem 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 <i>V</i>_mem 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 <i>V</i>_mem of limb mesenchyme switches from a hyperpolarized to depolarized state during early chondrocyte differentiation. This change in <i>V</i>_mem increases intracellular Ca²⁺ signaling through Ca²⁺ influx, via Ca_V1.2, 1 of L-type voltage-gated Ca²⁺ channels (VGCCs). We find that Ca_V1.2 activity is essential for chondrogenesis in the developing limbs. Pharmacological inhibition by an L-type VGCC specific blocker, or limb-specific deletion of Ca_V1.2, down-regulates expression of genes essential for chondrocyte differentiation, including <i>Sox9</i>, <i>Col2a1</i>, and <i>Agc1</i>, and thus disturbs proper cartilage formation. The Ca²⁺-dependent transcription factor NFATc1, which is a known major transducer of intracellular Ca²⁺ signaling, partly rescues Sox9 expression. These data reveal instructive roles of Ca_V1.2 in limb development, and more generally expand our understanding of how modulation of membrane potential is used as a mechanism of developmental regulation.