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Diacylglycerol kinases regulate TRPV1 channel activity
Luyu Liu1, Yevgen Yudin1, Tibor Rohacs2
1Department of Pharmacology, Physiology, and Neuroscience, Rutgers New Jersey Medical School, Newark, New Jersey, USA.
The Journal of Biological Chemistry
|April 30, 2020
Summary
Diacylglycerol kinase (DAGK) enzymes limit diacylglycerol (DAG) formation, reducing desensitization of the heat and capsaicin sensor, TRPV1. DAGK inhibition enhances TRPV1 desensitization, revealing its role in ion channel regulation.
Area of Science:
- Neuroscience
- Molecular Biology
- Biochemistry
Background:
- The Transient Receptor Potential Vanilloid 1 (TRPV1) channel, activated by heat and capsaicin, desensitizes due to calcium influx-mediated phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) hydrolysis.
- Diacylglycerol (DAG), a product of this hydrolysis, activates protein kinase C (PKC), which can modulate TRPV1 activity.
Purpose of the Study:
- To investigate the role of diacylglycerol kinase (DAGK) in TRPV1 desensitization.
- To determine if DAG modulates TRPV1 activity during desensitization and if PKC is involved.
Main Methods:
- Inhibition of DAGK enzymes in native TRPV1-expressing dorsal root ganglion neurons and recombinant TRPV1 in HEK293 cells.
- Site-directed mutagenesis of putative PKC phosphorylation sites (Ser-502 and Ser-800) on TRPV1.
- Measurement of DAG levels following TRPV1 activation and M1 muscarinic receptor activation.
Main Results:
- Inhibition of DAGK enzymes significantly reduced TRPV1 desensitization in both native and recombinant systems.
- The desensitization-reducing effect of DAGK inhibition was abolished by mutating Ser-502 and Ser-800, implicating PKC.
- TRPV1 activation caused a transient increase in DAG, which was amplified by DAGK inhibition, unlike M1 muscarinic receptor activation.
Conclusions:
- Calcium influx through TRPV1 activates both phospholipase C (PLC) and DAGK.
- DAGK negatively regulates TRPV1 channel activity by limiting DAG formation.
- This study uncovers a novel role for DAGK in the regulation of ion channel activity.
Keywords:
DAGKPKCTRPV1calciumdiacylglyceroldorsal root gangliaphosphoinositidetransient receptor potential channels (TRP channels)More Related Videos
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