PMID- 10488100
OWN - NLM
STAT- MEDLINE
DCOM- 19991104
LR  - 20220227
IS  - 0021-9258 (Print)
IS  - 0021-9258 (Linking)
VI  - 274
IP  - 39
DP  - 1999 Sep 24
TI  - Agonist-induced, G protein-dependent and -independent down-regulation of the mu
      opioid receptor. The receptor is a direct substrate for protein-tyrosine kinase.
PG  - 27610-6
AB  - The mu opioid receptor (MOR) has been shown to desensitize after 1 h of exposure 
      to the opioid peptide, [D-Ala(2), N-MePhe(4), Gly-ol(5)]enkephalin (DAMGO),
      largely by the loss of receptors from the cell surface and receptor
      down-regulation. We have previously shown that the Thr(394) in the carboxyl tail 
      is essential for agonist-induced early desensitization, presumably by serving as 
      a primary phosphorylation site for G protein-coupled receptor kinase. Using a
      T394A mutant receptor, we determined that Thr(394) was also responsible for mu
      opioid receptor down-regulation. The T394A mutant receptor displayed 50%
      reduction of receptor down-regulation (14.8%) compared with wild type receptor
      (34%) upon 1 h of exposure to DAMGO. Agonist-induced T394A receptor
      down-regulation was unaffected by pertussis toxin treatment, indicating
      involvement of a mechanism independent of G protein function. Interestingly,
      pertussis toxin-insensitive T394A receptor down-regulation was completely
      inhibited by a tyrosine kinase inhibitor, genistein. Tyrosine kinase inhibition
      blocked wild type MOR down-regulation by 50%, and the genistein-resistant wild
      type MOR down-regulation was completely pertussis toxin-sensitive. Following
      DAMGO stimulation, MOR was shown to be phosphorylated at tyrosine residue(s),
      indicating that the receptor was a direct substrate for tyrosine kinase action.
      Mutagenesis of the four intracellular tyrosine residues resulted in complete
      inhibition of the G protein-insensitive MOR internalization. Therefore,
      agonist-induced MOR down-regulation appears to be mediated by two distinct
      cellular signal transduction pathways. One is G protein-dependent and
      GRK-dependent, which can be abolished by pertussis toxin treatment of wild type
      MOR or by mutagenesis of Thr(394). The other novel pathway is G
      protein-independent but tyrosine kinase-dependent, blocked by genistein
      treatment, and one in which Thr(394) has no regulatory role but phosphorylation
      of tyrosine residues appears essential.
FAU - Pak, Y
AU  - Pak Y
AD  - Department of Pharmacology, University of Toronto, Ontario M5S 1A8, Canada.
FAU - O'Dowd, B F
AU  - O'Dowd BF
FAU - Wang, J B
AU  - Wang JB
FAU - George, S R
AU  - George SR
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - J Biol Chem
JT  - The Journal of biological chemistry
JID - 2985121R
RN  - 0 (Enzyme Inhibitors)
RN  - 0 (Receptors, Opioid, mu)
RN  - 0 (Recombinant Proteins)
RN  - 0 (Virulence Factors, Bordetella)
RN  - 100929-53-1 (Enkephalin, Ala(2)-MePhe(4)-Gly(5)-)
RN  - 2ZD004190S (Threonine)
RN  - 36B82AMQ7N (Naloxone)
RN  - EC 2.4.2.31 (Pertussis Toxin)
RN  - EC 2.7.- (Protein Kinases)
RN  - EC 2.7.10.1 (Protein-Tyrosine Kinases)
RN  - EC 2.7.11.11 (Cyclic AMP-Dependent Protein Kinases)
RN  - EC 3.6.1.- (GTP-Binding Proteins)
SB  - IM
MH  - Amino Acid Sequence
MH  - Amino Acid Substitution
MH  - Animals
MH  - CHO Cells
MH  - Cell Line
MH  - Cricetinae
MH  - Cyclic AMP-Dependent Protein Kinases/metabolism
MH  - *Down-Regulation
MH  - Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
MH  - Enzyme Inhibitors/pharmacology
MH  - GTP-Binding Proteins/*metabolism
MH  - Molecular Sequence Data
MH  - Mutagenesis, Site-Directed
MH  - Naloxone/metabolism
MH  - Pertussis Toxin
MH  - Phosphorylation
MH  - Protein Kinases/metabolism
MH  - Protein-Tyrosine Kinases/*metabolism
MH  - Rats
MH  - Receptors, Opioid, mu/chemistry/genetics/*metabolism
MH  - Recombinant Proteins/chemistry/metabolism
MH  - Threonine
MH  - Transfection
MH  - Virulence Factors, Bordetella/pharmacology
EDAT- 1999/09/17 00:00
MHDA- 1999/09/17 00:01
CRDT- 1999/09/17 00:00
PHST- 1999/09/17 00:00 [pubmed]
PHST- 1999/09/17 00:01 [medline]
PHST- 1999/09/17 00:00 [entrez]
AID - 10.1074/jbc.274.39.27610 [doi]
AID - S0021-9258(19)52163-9 [pii]
PST - ppublish
SO  - J Biol Chem. 1999 Sep 24;274(39):27610-6. doi: 10.1074/jbc.274.39.27610.