[Functional specificity of T-type calcium channels and their roles in neuronal differentiation].

Calcium plays a central role in cell signaling and T-type calcium channels constitute a unique route for the entry of calcium ions in excitable cells. The genuine electrophysiological properties of T-type calcium channels include activation at low voltages and window currents in the range of cell membrane resting potential. T-type channels therefore generate a specific calcium influx likely to play an important role during early stages of development, in various cellular functions including cell proliferation, cell differentiation, gene transcription and hormone secretion. Such T-channel activities are also associated with several pathological situations. With the recent cloning of three T-type pore channel subunits, alpha 1G, alpha 1H and alpha 1I (also called Cav3.1, Cav3.2 and Cav3.3, respectively), it has become possible to investigate further the role of T-type channels in various cellular functions, including neuronal differentiation. Here we describe recent data obtained in our laboratory demonstrating how T-type channels generated by the alpha 1H subunit contribute to neuronal differentiation.