Ablation of P/Q-type Ca ²⁺ channel currents, altered synaptic transmission, and progressive ataxia in mice lacking the α _1A -subunit

TLDR

The α1A subunit is a voltage‑gated Ca²⁺ channel protein central to research on channel diversity and neurological disorders such as ataxia, dystonia, epilepsy, and migraine, yet its precise role in neurotransmission has not been directly tested. The study generated an α1A knockout mouse to directly assess how loss of the dominant Ca²⁺ channel alters neurotransmission and to model human α1A‑related diseases. α1A‑deficient mice were produced and displayed a rapidly progressive ataxic and dystonic phenotype that led to death within 3–4 weeks. Elimination of α1A abolished P‑ and Q‑type currents in cerebellar neurons, modified other Ca²⁺ channel densities, and shifted hippocampal synaptic transmission to rely more on N‑ and R‑type channels, while the mice exhibited severe ataxia and.

Abstract

The Ca 2+ channel α 1A -subunit is a voltage-gated, pore-forming membrane protein positioned at the intersection of two important lines of research: one exploring the diversity of Ca 2+ channels and their physiological roles, and the other pursuing mechanisms of ataxia, dystonia, epilepsy, and migraine. α 1A -Subunits are thought to support both P- and Q-type Ca 2+ channel currents, but the most direct test, a null mutant, has not been described, nor is it known which changes in neurotransmission might arise from elimination of the predominant Ca 2+ delivery system at excitatory nerve terminals. We generated α 1A -deficient mice (α 1A −/− ) and found that they developed a rapidly progressive neurological deficit with specific characteristics of ataxia and dystonia before dying ≈3–4 weeks after birth. P-type currents in Purkinje neurons and P- and Q-type currents in cerebellar granule cells were eliminated completely whereas other Ca 2+ channel types, including those involved in triggering transmitter release, also underwent concomitant changes in density. Synaptic transmission in α 1A −/− hippocampal slices persisted despite the lack of P/Q-type channels but showed enhanced reliance on N-type and R-type Ca 2+ entry. The α 1A −/− mice provide a starting point for unraveling neuropathological mechanisms of human diseases generated by mutations in α 1A .