PKC-dependent regulation of the receptor locus dominates functional consequences of cysteinyl leukotriene type 1 receptor activation.
Leukotrienes are important lipid mediators of asthma that contribute to airway inflammation and bronchoconstriction. Critical mechanisms for physiological regulation of the main G protein-coupled receptor (GPCR) mediating the leukotriene responses in asthma, cysteinyl leukotriene type 1 receptor (CysLT1R), have not been delineated. Although desensitization of GPCRs is a well-established phenomenon, studies demonstrating its physiological relevance are lacking. Here, we demonstrate that relief of PKC-mediated desensitization of endogenous CysLT1Rs augments multiple LTD4-stimulated cellular functions, with associated increases in intracellular signaling events. In analyses of airway smooth muscle contraction ex vivo, PKC inhibition augmented LTD4-stimulated contraction, and increased phosphoinositide hydrolysis and calcium flux in both murine and human airway smooth muscle cells. Similarly, for human monocytes, PKC inhibition augmented LTD4-stimulated calcium flux and cell migration assessed in transwell chamber experiments and also augmented LTD4-induced production of monocyte chemotactic protein assessed by ELISA. In contrast, PKC inhibition had no effect or slightly attenuated these cell functions and signaling events promoted by other receptor agonists, suggesting that despite antithetical effects on downstream events, desensitization of the CysLT1R is the principal mechanism by which PKC regulates the functional consequences of CysLT1R activation.
Deshpande
Deepak A
DA
Department of Internal Medicine and Center for Human Genomics, Wake Forest University Health Science, Winston-Salem, NC 27157, USA.
Pascual
Rodolfo M
RM
Wang
Si-Wei
SW
Eckman
Delrae M
DM
Riemer
Ellen C
EC
Funk
Colin D
CD
Penn
Raymond B
RB
D000818:Animals; D002118:Calcium / Q000097:blood; D018932:Chemokine CCL2 / Q000502:physiology; D002634:Chemotaxis, Leukocyte / Q000502:physiology; D006801:Humans; D001239:Inhalation / Q000502:physiology; D015289:Leukotrienes / Q000502:physiology; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D009000:Monocytes / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology*; D009130:Muscle, Smooth / Q000502:physiology; D010716:Phosphatidylinositols / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011493:Protein Kinase C / Q000378:metabolism*; D018077:Receptors, Leukotriene / Q000235:genetics / Q000502:physiology*; D014132:Trachea / Q000502:physiology
C111835:CCL2 protein, human; D018932:Chemokine CCL2; D015289:Leukotrienes; D008565:Membrane Proteins; D010716:Phosphatidylinositols; D018077:Receptors, Leukotriene; D011493:Protein Kinase C; C083169:leukotriene D4 receptor; D002118:Calcium