TY - JOUR
T1 - Identification of two serine residues essential for agonist-induced 5-HT2A receptor desensitization
AU - Gray, John
AU - Compton-Toth, Beth A.
AU - Roth, Bryan L.
PY - 2003/9/16
Y1 - 2003/9/16
N2 - 5-HT2A serotonin receptors represent the principal molecular targets for LSD-like hallucinogens and atypical antipsychotic drugs. It has been proposed that a dysregulation of 5-HT2A receptor-mediated signaling may contribute to the pathogenesis of schizophrenia and related diseases. A major mechanism for the attenuation of GPCR signaling following agonist activation typically involves the phosphorylation of serine and/or threonine residues by various kinases. Ser/Thr phosphorylation leads to the binding of accessory proteins and the uncoupling of the G proteins, thereby preventing further signaling. The molecular mechanisms by which 5-HT 2A receptors are desensitized are unknown, and to date, no residues essential for agonist-mediated desensitization have been identified. Thus, we mutated, individually or in groups, all of the 37 serines and threonines in the cytoplasmic domains of the 5-HT2A receptor and assessed the effects of these mutations on agonist-mediated desensitization. We discovered that mutation of two residues, S421 in the C-terminal tail and S188 in the second intracellular loop, to alanine resulted in a significant block of agonist-induced desensitization. Intriguingly, a single-nucleotide polymorphism, of unreported frequency, at the S421 locus has been reported (S421F); the S421F mutation, like the S421A mutation, significantly attenuated agonist-mediated desensitization. Taken together, these findings indicate that the process of agonist-mediated desensitization of 5-HT2A receptors requires the presence of two nonconserved serine residues located in distinct intracellular loops.
AB - 5-HT2A serotonin receptors represent the principal molecular targets for LSD-like hallucinogens and atypical antipsychotic drugs. It has been proposed that a dysregulation of 5-HT2A receptor-mediated signaling may contribute to the pathogenesis of schizophrenia and related diseases. A major mechanism for the attenuation of GPCR signaling following agonist activation typically involves the phosphorylation of serine and/or threonine residues by various kinases. Ser/Thr phosphorylation leads to the binding of accessory proteins and the uncoupling of the G proteins, thereby preventing further signaling. The molecular mechanisms by which 5-HT 2A receptors are desensitized are unknown, and to date, no residues essential for agonist-mediated desensitization have been identified. Thus, we mutated, individually or in groups, all of the 37 serines and threonines in the cytoplasmic domains of the 5-HT2A receptor and assessed the effects of these mutations on agonist-mediated desensitization. We discovered that mutation of two residues, S421 in the C-terminal tail and S188 in the second intracellular loop, to alanine resulted in a significant block of agonist-induced desensitization. Intriguingly, a single-nucleotide polymorphism, of unreported frequency, at the S421 locus has been reported (S421F); the S421F mutation, like the S421A mutation, significantly attenuated agonist-mediated desensitization. Taken together, these findings indicate that the process of agonist-mediated desensitization of 5-HT2A receptors requires the presence of two nonconserved serine residues located in distinct intracellular loops.
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U2 - 10.1021/bi035061z
DO - 10.1021/bi035061z
M3 - Article
C2 - 12962510
AN - SCOPUS:0042318792
VL - 42
SP - 10853
EP - 10862
JO - Biochemistry
JF - Biochemistry
SN - 0006-2960
IS - 36
ER -