CB1 cannabinoid receptor signalling is canonically mediated through inhibitory Gαi proteins, but signalling through other G proteins occurs under some circumstances; Gαs being the most characterised secondary pathway. Determinants of this signalling switch identified to date include Gαi blockade, CB1 /D2 dopamine receptor co-stimulation, CB1 agonist class, and cell background. The aim of this study was to examine the effects of receptor number and ligand dependence on CB1 signalling.
CB1 was expressed in HEK cells at different levels, and signalling characterisation was performed for cAMP by real-time BRET biosensor - CAMYEL - and for phospho-ERK by AlphaScreen. Characterisation of a novel irreversible antagonist of CB1 , AM6544, was performed by homogenate and whole cell radioligand binding assays.
In HEK cells expressing high levels of CB1 , agonist treatment resulted in cAMP stimulation; a response not previously known to be mediated by receptor number. Δ(9) -THC and BAY59-3074 increased cAMP only in high-expressing cells that had been pre-treated with pertussis toxin, and agonists demonstrated more diverse signalling profiles in the stimulatory pathway than they elicited in the canonical inhibitory pathway. CB1 pharmacological knockdown and Gαi 1 supplementation were sufficient to restore canonical Gαi signalling to high expressing cells. Constitutive signalling in both lower- and higher-expressing cells was Gαi -mediated.
CB1 coupling to opposing G proteins is determined by both receptor and G protein number, and this underpins a mechanism for non-canonical signalling in a fashion consistent with Gαs signalling. CB1 is known to mediate opposite consequences in endpoints such as tumour viability receptor number-dependently, and our study may help to explain such effects at the level of G protein coupling.
Pharmacology, Toxicology and Pharmaceutical Science
14
15%
Biochemistry, Genetics and Molecular Biology
13
14%
Neuroscience
12
13%
Agricultural and Biological Sciences
8
9%
Chemistry
3
3%
Other
11
12%
Unknown
32
34%
Attention Score in Context
Attention Score in Context
This research output has an Altmetric Attention Score of 3. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 03 January 2024.
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#8,430,276
of 25,177,382 outputs
Outputs from British Journal of Pharmacology
#2,812
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Outputs of similar age
#124,194
of 322,583 outputs
Outputs of similar age from British Journal of Pharmacology
#41
of 95 outputs
Altmetric has tracked 25,177,382 research outputs across all sources so far. This one is in the 43rd percentile – i.e., 43% of other outputs scored the same or lower than it.
So far Altmetric has tracked 7,684 research outputs from this source. They typically receive more attention than average, with a mean Attention Score of 8.0. This one is in the 25th percentile – i.e., 25% of its peers scored the same or lower than it.
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We're also able to compare this research output to 95 others from the same source and published within six weeks on either side of this one. This one has gotten more attention than average, scoring higher than 54% of its contemporaries.
