The C-terminal Src inhibitory kinase (Csk)-mediated tyrosine phosphorylation is a novel molecular mechanism to limit P2X3 receptor function in mouse sensory neurons.
On sensory neurons, sensitization of P2X(3) receptors gated by extracellular ATP contributes to chronic pain. We explored the possibility that receptor sensitization may arise from down-regulation of an intracellular signal negatively controlling receptor function. In view of the structural modeling between the Src region phosphorylated by the C-terminal Src inhibitory kinase (Csk) and the intracellular C terminus domain of the P2X(3) receptor, we investigated how Csk might regulate receptor activity. Using HEK cells and the in vitro kinase assay, we observed that Csk directly phosphorylated the tyrosine 393 residue of the P2X(3) receptor and strongly inhibited receptor currents. On mouse trigeminal sensory neurons, the role of Csk was tightly controlled by the extracellular level of nerve growth factor, a known algogen. Furthermore, silencing endogenous Csk in HEK or trigeminal cells potentiated P2X(3) receptor responses, confirming constitutive Csk-mediated inhibition. The present study provides the first demonstration of an original molecular mechanism responsible for negative control over P2X(3) receptor function and outlines a potential new target for trigeminal pain suppression.
D'Arco
Marianna
M
Neurobiology Sector and Italian Institute of Technology Unit, International School for Advanced Studies (SISSA), 34014 Trieste, Italy.
Giniatullin
Rashid
R
Leone
Vanessa
V
Carloni
Paolo
P
Birsa
Nicol
N
Nair
Asha
A
Nistri
Andrea
A
Fabbretti
Elsa
E
D000595:Amino Acid Sequence; D000818:Animals; D000081247:CSK Tyrosine-Protein Kinase; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008954:Models, Biological; D008969:Molecular Sequence Data; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058477:Receptors, Purinergic P2X3; D011984:Sensory Receptor Cells / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014443:Tyrosine / Q000737:chemistry*; D019061:src-Family Kinases
C546407:P2RX3 protein, human; C546409:P2rx3 protein, mouse; D018048:Receptors, Purinergic P2; D058477:Receptors, Purinergic P2X3; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; C000631346:CSK protein, human