A structural analysis of the splice-specific functional impact of the pathogenic familial hemiplegic migraine type 1 S218L mutation on Ca v 2.1 P/Q-type channel gating.

Autor: Sack AS; Michael Smith Laboratories, University of British Columbia, 2185 East Mall, Vancouver, BC, V6T 1Z4, Canada.; Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, BC, V6T 1Z3, Canada., Samera GJ; Applied Genomics Centre, Kwantlen Polytechnic University, 12666 - 72 Ave, Surrey, BC, V3W 2M8, Canada., Hissen A; Applied Genomics Centre, Kwantlen Polytechnic University, 12666 - 72 Ave, Surrey, BC, V3W 2M8, Canada., Wester RJ; Applied Genomics Centre, Kwantlen Polytechnic University, 12666 - 72 Ave, Surrey, BC, V3W 2M8, Canada., Garcia E; Michael Smith Laboratories, University of British Columbia, 2185 East Mall, Vancouver, BC, V6T 1Z4, Canada.; Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, BC, V6T 1Z3, Canada., Adams PJ; Applied Genomics Centre, Kwantlen Polytechnic University, 12666 - 72 Ave, Surrey, BC, V3W 2M8, Canada., Snutch TP; Michael Smith Laboratories, University of British Columbia, 2185 East Mall, Vancouver, BC, V6T 1Z4, Canada. snutch@msl.ubc.ca.; Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, BC, V6T 1Z3, Canada. snutch@msl.ubc.ca.
Jazyk: angličtina
Zdroj: Molecular brain [Mol Brain] 2024 Nov 20; Vol. 17 (1), pp. 82. Date of Electronic Publication: 2024 Nov 20.
DOI: 10.1186/s13041-024-01152-z
Abstrakt: P/Q-type (Ca v 2.1) calcium channels mediate Ca 2+ influx essential for neuronal excitability and synaptic transmission. The CACNA1A gene, encoding the Ca v 2.1 pore forming subunit, is highly expressed throughout the mammalian central nervous system. Alternative splicing of Ca v 2.1 pre-mRNA generates diverse channel isoforms with distinct biophysical properties and drug affinities, which are differentially expressed in nerve tissues. Splicing variants can also affect channel function under pathological conditions although their phenotypic implication concerning inherited neurological disorders linked to CACNA1A mutations remains unknown. Here, we quantified the expression of Ca v 2.1 exon 24 (e24) spliced transcripts in human nervous system samples, finding different levels of expression within discrete regions. The corresponding Ca v 2.1 variants, differing by the presence (+) or absence (Δ) of Ser-Ser-Thr-Arg residues (SSTR) in the domain III S3-S4 linker, were functionally characterized using patch clamp recordings. Further, the + /ΔSSTR isoforms were used to demonstrate the differential impact of the Familial Hemiplegic Migraine Type 1 (FHM-1) S218L mutation, located in the domain I S4-S5 linker, on the molecular structure and electrophysiological properties of Ca v 2.1 isoforms. S218L has a prominent effect on the voltage-dependence of activation of +SSTR channels when compared to ΔSSTR, indicating a differential effect of the mutation depending on splice-variant context. Structural modeling based upon Cav2.1 cryo-EM data provided further insight reflecting independent contributions of amino acids in distant regions of the channel on gating properties. Our modelling indicates that by increasing hydrophobicity the Leu218 mutation contributes to stabilizing a structural conformation in which the domain I S4-S5 linker is oriented alongside the inner plasma membrane, similar to that occurring when S4 is translocated upon activation.The SSTR insertion appears to exert an influence in the local electric field of domain III due to an change in the distribution of positively charged regions surrounding the voltage sensing domain, which we hypothesize impacts its movement during the transition to the open state. In summary, we reveal molecular changes correlated with distinct functional effects provoked by S218L FHM-1 mutation in hCa v 2.1 splice isoforms whose differential expression could impact the manifestation of the neurological disorder.
Competing Interests: Declarations. Ethics approval and consent to participate: Not applicable. Consent for publication: Not applicable. Competing interests: The authors declare that they have no competing interests.
(© 2024. The Author(s).)
Databáze: MEDLINE
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