Homologous and Heterologous Phosphorylation of the AT2 Angiotensin Receptor by Protein Kinase C
- 1Endocrinology and Reproduction Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (J.A.O.-R., S.J., K.J.C., R.D.S.); and 2Department of Physiology, Semmelweis University of Medicine, Budapest, Hungary (L.H.)
Abstract
The angiotensin AT2 receptor is an atypical seven transmembrane domain receptor that is coupled to activation of tyrosine phosphatase and inhibition of MAP kinase, and does not undergo agonist-induced internalization. An investigation of the occurrence and nature of AT2 receptor phosphorylation revealed that phorbol ester-induced activation of protein kinase C (PKC) in HA-AT2 receptor-expressing COS-7 cells caused rapid and specific phosphorylation of a single residue (Ser354) located in the cytoplasmic tail of the receptor. Agonist activation of AT2 receptors by angiotensin II (Ang II) also caused rapid PKC-dependent phosphorylation of Ser354 that was prevented by the AT2antagonist, PD123177, and by inhibitors of PKC. In cells coexpressing AT1 and AT2 receptors, Ang II-induced phosphorylation of the AT2 receptor was reduced by either PD123177 or the AT1 receptor antagonist, DuP753, and was abolished by treatment with both antagonists or with PKC inhibitors. These findings indicate that the AT2 receptor is rapidly phosphorylated via PKC during homologous activation by Ang II, and also undergoes heterologous PKC-dependent phosphorylation during activation of the AT1 receptor. The latter process may regulate the counteracting effects of AT2 receptors on growth responses to AT1 receptor activation.
Footnotes
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Send reprint requests to: Kevin J. Catt, ERRB, NICHD, National Institutes of Health, Bldg. 49, Rm. 6A-36, 49 Convent Dr., Bethesda, MD 20892. E-mail: catt{at}helix.nih.gov
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J.A.O-R. was supported by a Pan American Fellowship (NIH/CONACYT 979004). L.H. was supported in part by an International Research Scholar Award from the Howard Hughes Medical Institute and a Collaborative Research Initiative Grant from the Wellcome Trust (051804/Z/97/Z). S.J. was supported in part by an Alpha Omega Alpha Student Fellowship.
- Abbreviations:
- GPCR
- G protein-coupled receptor
- AT1-R and AT2-R
- types 1 and 2 angiotensin II receptors, respectively
- β2-AR
- β2-adrenergic receptor
- BIM
- bisindolylmaleimide
- DG
- diacylglycerol
- DMEM
- Dulbecco's modified Eagle's medium
- GRK
- G protein-coupled receptor kinase
- HA
- hemagglutinin
- PKC
- protein kinase C
- PNGase F
- peptide N-glycosidase F
- SP
- staurosporine
- TFMS
- trifluoromethanesulfonic acid
- TPA
- 12-O-tetradecanoylphorbol 13-acetate
- Ang II
- angiotensin II
- PAGE
- polyacrylamide gel electrophoresis
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- Received June 12, 2000.
- Accepted August 10, 2000.
- The American Society for Pharmacology and Experimental Therapeutics
