Sequential ionic and conformational signaling by calcium channels drives neuronal gene expression

Area of Science:

• Neuroscience
• Molecular Biology
• Biophysics

Background:

• Voltage-gated CaV1.2 channels are key to neural plasticity.
• The signaling mechanisms of CaV1.2, involving calcium influx and voltage-dependent conformational changes, remain unclear.

Purpose of the Study:

• To elucidate the distinct roles of Ca2+ influx and voltage-dependent conformational change (VΔC) in CaV1.2 channel function.
• To determine the signaling requirements for transcription-dependent neural plasticity mediated by CaV1.2.

Main Methods:

• Engineered a fusion protein linking CaV1.2 to a ligand-gated Ca2+-permeable channel for independent signal control.
• Manipulated the timing and presence of Ca2+ and VΔC signals to assess their impact on transcription.

Main Results:

• CaV1.2 requires a sequential signaling mechanism: Ca2+ influx mobilizes Ca2+/calmodulin-dependent protein kinase II (CaMKII), followed by VΔC-mediated accumulation.
• Neither Ca2+ nor VΔC alone was sufficient for transcriptional activation; signal order was critical, with optimal activation occurring when Ca2+ preceded VΔC by 10-20 seconds.
• VΔC synergistically enhanced N-methyl-D-aspartate receptor signaling, and its dysfunction correlated with autistic symptoms in Timothy syndrome.

Conclusions:

• Non-ionic VΔC signaling is essential for CaV1.2 channel function in synaptic plasticity and neuropsychiatric processes.
• CaV1.2 mediates transcription-dependent neural plasticity through a dual, order-dependent signaling pathway involving both Ca2+ and VΔC.