Differential regulation of Cav2.2 channel exon 37 variants by alternatively spliced μ-opioid receptors Journal Article
| Authors: | Gandini, M. A.; Souza, I. A.; Raval, D.; Xu, J.; Pan, Y. X.; Zamponi, G. W. |
| Article Title: | Differential regulation of Cav2.2 channel exon 37 variants by alternatively spliced μ-opioid receptors |
| Abstract: | We have examined the regulation of mutually exclusive Cav2.2 exon 37a and b variants by the mouse μ-opioid receptor (mMOR) C-terminal splice variants 1, 1C and 1O in tsA-201 cells. Electrophysiological analyses revealed that both channel isoforms exhibit DAMGO-induced voltage-dependent (Gβγ-mediated) inhibition and its recovery by voltage pre-pulses, as well as a voltage-independent component. However, the two channel isoforms differ in their relative extent of voltage-dependent and independent inhibition, with Cav2.2-37b showing significantly more voltage-dependent inhibition upon activation of the three mMOR receptors studied. In addition, coexpression of either mMOR1 or mMOR1C results in an agonist-independent reduction in the peak current density of Cav2.2-37a channels, whereas the peak current density of Cav2.2-37b does not appear to be affected. Interestingly, this decrease is not due to an effect on channel expression at the plasma membrane, as demonstrated by biotinylation experiments. We further examined the mechanism underlying the agonist-independent modulation of Cav2.2-37a by mMOR1C. Incubation of cells with pertussis toxin did not affect the mMOR1C mediated inhibition of Cav2.2-37a currents, indicating a lack of involvement of Gi/o signaling. However, when a Src tyrosine kinase inhibitor was applied, the effect of mMOR1C was lost. Moreover, when we recorded currents using a Cav2.2-37a mutant in which tyrosine 1747 was replaced with phenylalanine (Y1747F), the agonist independent effects of mMOR1C were abolished. Altogether our findings show that Cav2.2-37a and Cav2.2-37b isoforms are subject to differential regulation by C-terminal splice variants of mMORs, and that constitutive mMOR1C activity and downstream tyrosine kinase activity exert a selective inhibition of the Cav2.2-37a splice variant, an N-type channel isoform that is highly enriched in nociceptors. Our study provides new insights into the roles of the MOR full-length C-terminal variants in modulating Cav2.2 channel isoform activities. © 2019 The Author(s). |
| Keywords: | protein expression; unclassified drug; exon; nonhuman; mouse; enzyme inhibition; carboxy terminal sequence; genetic variability; enzyme activation; enzyme activity; protein tyrosine kinase; tyrosine; enzyme regulation; cell membrane; mu opiate receptor; enzyme mechanism; rna splicing; phenylalanine; biotinylation; opioid receptor; splicing; pertussis toxin; incubation time; enkephalin[2 dextro alanine 4 methylphenylalanine 5 glycine]; calcium channel; priority journal; article; g proteins; electrophysiological procedures; pain receptor; n-type; cav2.2; calcium channel n type; protein cav2.2 channel; protein mu opiate receptor 1; protein mu opiate receptor 1c; voltage gated chloride channel; current density; tsa201 cell line |
| Journal Title: | Molecular Brain |
| Volume: | 12 |
| ISSN: | 1756-6606 |
| Publisher: | BioMed Central Ltd. |
| Date Published: | 2019-11-27 |
| Start Page: | 98 |
| Language: | English |
| DOI: | 10.1186/s13041-019-0524-6 |
| PUBMED: | 31775826 |
| PROVIDER: | scopus |
| PMCID: | PMC6880636 |
| DOI/URL: | |
| Notes: | Article -- Source: Scopus |
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