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Discovery and characterization of two novel CB 1 receptor splice variants with modified N‐termini in mouse
Author(s) -
Ruehle Sabine,
WagerMiller James,
Straiker Alex,
Farnsworth Jill,
Murphy Michelle N.,
Loch Sebastian,
Monory Krisztina,
Mackie Ken,
Lutz Beat
Publication year - 2017
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/jnc.14099
Subject(s) - splice , receptor , alternative splicing , hek 293 cells , agonist , biology , 5 ht5a receptor , glycosylation , microbiology and biotechnology , amino acid , rna splicing , g protein coupled receptor , chemistry , exon , biochemistry , gene , rna
Abstract Numerous studies have been carried out in the mouse model, investigating the role of the cannabinoid receptor type 1 ( CB 1). However, mouse CB 1 ( mCB 1) receptor differs from human CB 1 ( hCB 1) receptor in 13 amino acid residues. Two splice variants, hCB 1a and hCB 1b, diverging in their amino‐termini, have been reported to be unique for hCB 1 and, via different signaling properties, contribute to CB 1 receptor physiology and pathophysiology. We hypothesized that splice variants also exist for the mCB 1 receptor and have different signaling properties. On murine hippocampal cDNA , we identified two novel mCB 1 receptor splice variants generated by splicing of introns with 117 bp and 186 bp in the N‐terminal domain, corresponding to deletions of 39 or 62 amino acids, respectively. The mRNA s for the splice variants mCB 1a and mCB 1b are expressed at low levels in different brain regions. Western blot analysis of protein extracts from stably transfected HEK 293 cells indicates a strongly reduced glycosylation because of the absence of two glycosylation sites in mCB 1b. On‐cell western analysis in these stable lines revealed increased internalization of mCB 1a and mCB 1b upon stimulation with the agonist WIN 55,212‐2 as compared to mCB1. Results also point toward an increased affinity to SR 141716 for mCB 1a, as well as slightly enhanced inhibition of neurotransmission compared to mCB 1. In mCB 1b, agonist‐induced MAPK phosphorylation was decreased compared to mCB 1 and mCB 1a. Identification of mouse CB 1 receptor splice variants may help to explain differences found between human and mouse endocannabinoid systems and improve the understanding of CB 1 receptor signaling and trafficking in different species.