Biology subjects

Yudin, Y.

Publications and source records attributed to Yudin, Y..

3 recordsLinked to original sources

bioRxiv2018

The G protein-biased PZM21 and TRV130 act as partial agonists of μ-opioid receptors signaling to ion channel targets

Opioids exert many of their acute effects through modulating ion channels via G{beta}{gamma} subunits. Some of their side effects are attributed to {beta}-arrestin recruitment, and several biased agonists that do not activate this pathway have been developed recently. Here we tested the effects of TRV130, PZM21 and herkinorin, three G-protein biased agonists of -opioid receptors (OR), on ion channel targets. Compared to the full OR agonist DAMGO, all three biased agonists induced smaller activation of G protein-coupled inwardly rectifying potassium channels (GIRK2), and smaller inhibition of Transient Receptor Potential Melastatin (TRPM3) channels. Furthermore, co-application of TRV130 or PZM21, but not herkinorin reduced the effects of DAMGO on both ion channels. CaV2.2 was also inhibited less by PZM21 and TRV130 than by DAMGO. TRV130, PZM21 and herkinorin were also less effective than DAMGO in inducing dissociation of the Gi /G{beta}{gamma} complex. We conclude that TRV130, PZM21 are partial agonists of OR.

pharmacology and toxicology↗

bioRxiv2018

Gαq sensitizes TRPM8 to inhibition by PI(4,5)P2 depletion upon receptor activation

Activation of G-protein coupled receptors (GPCRs) was proposed to inhibit the cold and menthol sensitive Transient Receptor Potential Melastatin 8 (TRPM8) channels via direct binding of Gq to the channel. It is well documented that TRPM8 requires the plasma membrane phospholipid phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2 or PIP2] for activity. It was claimed however that a decrease in cellular levels of this lipid does not contribute to channel inhibition upon receptor activation. Here we show that supplementing the whole cell patch pipette with PI(4,5)P2 reduced inhibition of TRPM8 by activation of Gq-coupled receptors in mouse dorsal root ganglion (DRG) neurons. Activation of the same receptors induced Phospholipase C (PLC) activation and decreased plasma membrane PI(4,5)P2 levels in these neurons. PI(4,5)P2 also reduced inhibition of TRPM8 by activation of heterologously expressed Gq-coupled muscarinic M1 receptors. Co-expression of a constitutively active Gq protein that does not couple to PLC inhibited TRPM8 activity, and in cells expressing this protein decreasing PI(4,5)P2 levels using a voltage sensitive 5-phosphatase induced a stronger inhibition of TRPM8 activity than in control cells. Our data indicate that PI(4,5)P2 depletion plays an important role in TRPM8 inhibition upon GPCR activation, and Gq inhibits the channel by reducing its apparent affinity for PI(4,5)P2 and thus sensitizes the channel to inhibition by decreasing PI(4,5)P2 levels.

neuroscience↗

bioRxiv2018

A consistent picture of TRPV1 activation emerges from molecular simulations and experiments

Although the structure of TRPV1 has been experimentally determined in both the closed and open states, very little is known about its activation mechanism. In particular, the conformational changes occurring in the pore domain and resulting in ionic conduction have not been identified yet. Here, we suggest a hypothetical molecular mechanism for TRPV1 activation, which involves the rotation of a conserved asparagine in S6 from the S4-S5 linker toward the pore. This rotation is correlated with the dehydration of four peripheral cavities located between S6 and the S4-S5 linker and the hydration of the pore. In light of our hypothesis, we perform bioinformatics analyses of TRP and other evolutionary related ion channels, analyze newly available structures and re-examine previously reported water accessibility and mutagenesis experiments. Overall, we provide several independent lines of evidence that corroborate our hypothesis. Finally, we show that the proposed molecular mechanism is compatible with the currently existing idea that in TRPV1 the selectivity filter acts as a secondary gate.

biophysics↗