Anti-nociceptive action of peripheral mu-opioid receptors by G-beta-gamma protein-mediated inhibition of TRPM3 channels

Rohács

2019

British J Pharmacology

Background and Purpose Opioids remain the most efficient medications against severe pain; they act on receptors that couple to heterotrimeric G‐proteins in the Gαi/o family. Opioids exert many of their acute effects through modulating ion channels via Gβγ subunits. Many of their side effects are attributed to β‐arrestin recruitment. Several biased agonists that do not recruit β‐arrestins, but activate G‐protein‐dependent pathways, have recently been developed. While these compounds have been proposed to be full agonists of G‐protein signalling in several high throughput pharmacological assays, their effects were not studied on ion channel targets. Experimental Approach Here, we used patch‐clamp electrophysiology and Ca2+ imaging to test the effects of TRV130, PZM21, and herkinorin, three G‐protein‐biased agonists of μ‐opioid receptors, on ion channel targets of Gαi/o/Gβγ signalling. We also studied G‐protein dissociation using a FRET‐based assay. Key Results All three biased agonists induced smaller activation of G‐protein‐coupled inwardly rectifying K+ channels (Kir3.2) and smaller inhibition of transient receptor potential melastatin (TRPM3) channels than the full μ receptor agonist DAMGO. Co‐application of TRV130 or PZM21, but not herkinorin, alleviated the effects of DAMGO on both channels. PZM21 and TRV130 also decreased the effect of morphine on Kir3.2 channels. The CaV2.2 channel was also inhibited less by PZM21 and TRV130 than by DAMGO. We also found that TRV130, PZM21, and herkinorin were less effective than DAMGO at inducing dissociation of the Gαi/Gβγ complex. Conclusion and Implications TRV130, PZM21, and potentially herkinorin are partial agonists of μ receptors.

Section: Discussioncontrasting

confidence: 97%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

The G‐protein‐biased agents PZM21 and TRV130 are partial agonists of μ‐opioid receptor‐mediated signalling to ion channels

Rohács

2019

British J Pharmacology

“…While TRPM3 -/mice show defects in noxious heat sensation, the channel shows increased activity well below the noxious range, when temperature is increased from 15 o C to 26 o C, with further increases in activity at 37 o C (Vriens et al, 2011). TRPM3 is also inhibited by activation of Gi-coupled receptors such as μ-opioid receptors and GABAB receptors in DRG neurons, and agonists of those receptors reduced nocifensive reactions to local injection of TRPM3 agonists (Badheka et al, 2017;Dembla et al, 2017;Quallo et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Disease-associated mutations in TRPM3 render the channel overactive via two distinct mechanisms

Zhao

Rohács

2020

Preprint

Transient Receptor Potential Melastatin 3 (TRPM3) is a Ca 2+ permeable non-selective cation channel activated by heat and chemical agonists such as pregnenolone sulfate and CIM0216. TRPM3 mutations in humans were recently reported to be associated with intellectual disability and epilepsy; the functional effects of those mutations however were not reported. Here we show that both disease-associated mutations of TRPM3 render the channel overactive, but likely via different mechanisms. The Val to Met substitution in the S4-S5 loop induced a larger increase in basal activity and agonist sensitivity at room temperature than the Pro to Gln substitution in the extracellular segment of S6. In contrast, heat activation was increased more by the S6 mutant than by the S4-S5 segment mutant. Both mutants were inhibited by the TRPM3 antagonist primidone, suggesting a potential therapeutic intervention to treat this disease.

“…Whether the activation of Gi-coupled receptors influence the activity of Piezo2 channels has not been studied yet. Activation of Gi-coupled receptors leads to inhibition of adenylate cyclase, activation of G-protein coupled inwardly rectifying K + (GIRK) channels and inhibition of voltage-gated Ca 2+ channels (VGCC) and of transient receptor potential melastatin 3 (TRPM3) channels in DRG neurons through direct binding of Gβγ (Badheka et al, 2017;Dembla et al, 2017;Quallo et al, 2017;Reuveny et al, 1994;Robertson and Taylor, 1986). In addition, Gβγ is also known to induce the activation of phosphoinositide 3-kinase gamma (PI3Kγ) and mitogen-activated protein kinase (MAPK) (Clapham and Neer, 1997;Khan et al, 2013;Lopez-Ilasaca et al, 1997;Touhara et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

Gi-Coupled Receptor Activation Potentiates Piezo2 Currents via Gβγ

Rosario

et al. 2019

Preprint

SUMMARYDysregulation of mechanosensitive Piezo2 channels is a hallmark of mechanical allodynia, yet the cellular mechanisms that sensitize mechanoreceptors are still poorly understood. Activation of Gi-coupled receptors sensitizes Piezo2 currents, but whether Gi-coupled receptors regulate the activity of Piezo2 channels is not known. Here, we found that activation of Gi-coupled receptors potentiates Piezo2 currents in dorsal root ganglion (DRG) neurons and in heterologous systems, but inhibits Piezo1 currents in heterologous systems. The potentiation, or inhibition of Piezo currents is abolished when blocking Gβγ with the c-terminal domain of the beta-adrenergic kinase (βARKct). Pharmacological inhibition of kinases downstream of Gβγ, phosphoinositide 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK), also abolished the potentiation of Piezo2 currents. Hence, our studies illustrate an indirect mechanism of action of Gβγ to sensitize Piezo2 currents after activation of Gi-coupled receptors.