Regulation of voltage-sensitivity of CaV1 calcium channels

Voltage-gated calcium channels control numerous important body functions, including muscle contraction, hormone and neurotransmitter secretion, and activity-dependent regulation of genes. To do so these membrane proteins are capable of sensing voltage changes in the membranes of excitable cells and, in response, open a calcium-selective pore to allow influx of calcium that then activates the respective cell function. Interestingly, voltage-gated calcium channels come in many different flavors with distinct voltage-sensitivities fine-tuned to the demands of the specific cell function. In turn, pathological alterations of the activation properties of calcium channels are involved in a wide range of human diseases, including muscle weakness, cardiac arrhythmias, diabetes, and multiple neurological and psychiatric disorders. Accordingly, drugs modifying channel activity are used to treat several of these diseases. Therefore, understanding the molecular mechanisms regulating voltage-sensing and gating of calcium channels is of great importance in the biomedical sciences. Here we propose to apply a combination of cutting-edge molecular and electrophysiological techniques, as well as novel computational approaches to unravel the molecular mechanism by which calcium channels determine their specific voltage sensitivities and adjust it to changing demands. The applied methods allow measuring the minute calcium currents passing through single channels, simulating the sequential interactions of individual amino acids during the voltage-sensing process at atomic resolution, and experimentally testing the function of these molecular interactions by genetically modifying individual amino acids in the channels. The results of this study are expected to significantly increase our understanding of the workings of voltage-gated calcium channels; how they regulate their activation properties and why they differ so much between specific channel isoforms. Moreover, this project is expected to provide the first functional evidence of a new channel variant recently discovered by our group in native skeletal muscle cells. Together the expected findings will significantly contribute to our knowledge of calcium channel function and lay the basis for future efforts to develop isoform-specific drugs targeting specific calcium channels involved in the etiology or pathophysiology of disease.

THE MOLECULAR MECHANISMS REGULATING THE VOLTAGE-SENSITIVITY OF CaV1 CALCIUM CHANNELS Voltage-gated calcium channels control numerous important body functions, including muscle contraction, hormone and neurotransmitter secretion, and activity-dependent regulation of genes. To do so these membrane proteins are capable of sensing voltage changes in the membranes of excitable cells and, in response, open a calcium-selective pore to allow influx of calcium that then activates the respective cell function. Interestingly, voltage-gated calcium channels come in many different flavors with distinct voltage-sensitivities fine-tuned to the demands of the specific cell function. In turn, pathological alterations of the activation properties of calcium channels are involved in a wide range of human diseases, including muscle weakness, cardiac arrhythmias, diabetes, and multiple neurological and psychiatric disorders. Accordingly, drugs modifying channel activity are used to treat several of these diseases. Therefore, understanding the molecular mechanisms regulating voltage-sensing and gating of calcium channels is of great importance in the biomedical sciences. In this project we applied a combination of cutting-edge molecular and electrophysiological techniques, as well as novel computational approaches to unravel the molecular mechanism by which calcium channels determine their specific voltage sensitivities and adjust it to changing demands. The applied methods involved measuring the calcium currents passing through the channels, simulating the sequential interactions of individual amino acids during the voltage-sensing process at atomic resolution, and experimentally testing the function of these molecular interactions by genetically modifying individual amino acids in the channels. The results of this study significantly increases our understanding of the workings of voltage-gated calcium channels; how they regulate their activation properties and why they differ so much between specific channel isoforms. This knowledge could already be applied to the characterization of several genetic variants of calcium channel genes found in patients with neurodevelopmental disease and epilepsy. Together, the findings of this project significantly contribute to our knowledge of calcium channel function and lay the basis for future efforts to develop isoform-specific drugs targeting specific calcium channels involved in the etiology or pathophysiology of disease.