A single mutation in helix 8 enhances the angiotensin II type 1a receptor transport and signaling.
The amphipathic helix 8 in the membrane-proximal C-terminus is a structurally conserved feature of class A seven transmembrane-spanning G protein-coupled receptors (GPCRs). Mutations of this helical motif often cause receptor misfolding, defective cell surface transport and dysfunction. Surprisingly, we demonstrated here that a single point mutation at Lys308 in helix 8 markedly enhanced the steady-state surface density of the angiotensin II type 1a receptor (AT1aR). Consistent with the enhanced cell surface expression, Lys308 mutation significantly augmented AT1aR-mediated mitogen-activated protein kinase ERK1/2 activation, inositol phosphate production, and vascular smooth muscle cell migration. This mutation also increased the overall expression of AT1aR without altering receptor degradation. More interestingly, Lys308 mutation abolished AT1aR interaction with β-COP, a component of COPI transport vesicles, and impaired AT1aR responsiveness to the inhibition of Rab6 GTPase involved in the Golgi-to-ER retrograde pathway. Furthermore, these functions of Lys308 were largely dependent on its positively charged property. These data reveal previously unappreciated functions of helix 8 and novel mechanisms governing the cell surface transport and function of AT1aR.
Department of Pharmacology and Toxicology, Medical College of Georgia, Georgia Regents University, 1459 Laney Walker Blvd., Augusta GA 30912, United States.
Shu
S
Zhu
Department of Pharmacology and Toxicology, Medical College of Georgia, Georgia Regents University, 1459 Laney Walker Blvd., Augusta GA 30912, United States.
Maoxiang
M
Zhang
Department of Pharmacology and Toxicology, Medical College of Georgia, Georgia Regents University, 1459 Laney Walker Blvd., Augusta GA 30912, United States.
Jason E
JE
Davis
Department of Pharmacology and Toxicology, Medical College of Georgia, Georgia Regents University, 1459 Laney Walker Blvd., Augusta GA 30912, United States.
William H
WH
Wu
Department of Pharmacology and Toxicology, Medical College of Georgia, Georgia Regents University, 1459 Laney Walker Blvd., Augusta GA 30912, United States.
Kristen
K
Surrao
School of Life Sciences and Technology, Tongji University, 1239 Siping Road, Shanghai, China.
Hong
H
Wang
Department of Pharmacology and Toxicology, Medical College of Georgia, Georgia Regents University, 1459 Laney Walker Blvd., Augusta GA 30912, United States. Electronic address: guwu@gru.edu.
Guangyu
G
Wu
D000595:Amino Acid Sequence; D000818:Animals; D001011:Aorta / Q000166:cytology; D002465:Cell Movement; D020755:Coat Protein Complex I / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D007295:Inositol Phosphates / Q000096:biosynthesis; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D020125:Mutation, Missense; D032389:Myocytes, Smooth Muscle / Q000502:physiology; D011485:Protein Binding; D017433:Protein Structure, Secondary; D021381:Protein Transport; D051381:Rats; D044140:Receptor, Angiotensin, Type 1 / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D054875:Ubiquitination; D020691:rab GTP-Binding Proteins / Q000378:metabolism
D020755:Coat Protein Complex I; D007295:Inositol Phosphates; C094135:Rab6 protein; D044140:Receptor, Angiotensin, Type 1; D020691:rab GTP-Binding Proteins
Angiotensin II receptor; G protein-coupled receptor; Signaling; Trafficking