title: Lack of evidence for AT1R/B2R heterodimerization in COS-7, HEK293, and NIH3T3 cells: how common is the AT1R/B2R heterodimer?
abstract: It has been suggested previously ( AbdAlla, S., Lother, H., and Quitterer, U. (2000) Nature 407, 94-98 ) that the angiotensin II type 1 receptor (AT1R) and the bradykinin B2 receptor (B2R) form constitutive heterodimers. Furthermore they demonstrate that AT1R signaling significantly increases in the presence of the B2R. These findings suggest that heterodimerization and potentiation of AT1R signaling is a universal phenomenon that occurs as a natural consequence of simultaneous expression of the two receptors. Hence this potential interaction is of great pharmacological and biological interest that adds an additional layer of complexity to the understanding of the cross-talk between the renin-angiotensin and kallikrein-kinin systems. Given the remarkable significance of this finding, scientists from four independent research groups have set out to reproduce and further examine the potential AT1R/B2R interaction. We have investigated functional potentiation by the B2R of AT1R signaling in three different cell lines using multiple assays including phosphoinositide hydrolysis, ERK activation, beta-arrestin recruitment, and receptor selection and amplification technology, and we have examined dimerization using bioluminescence resonance energy transfer and regulated secretion/aggregation technology. However, although both the AT1Rs and B2Rs were functional in our systems and the systems were fine tuned to detect small changes in receptor function, we failed to detect any functional modulation by or physical interaction between the two receptor proteins. In contrast to the previous observations, our data collectively suggest that AT1R/B2R heterodimerization does not occur as a natural consequence of their simultaneous expression in the same cell nor does the B2R influence the AT1R signaling.
authors.affiliation: Laboratory for Molecular Cardiology, The Danish National Research Foundation Centre for Cardiac Arrhythmia, The Heart Centre, Copenhagen University Hospital, Copenhagen, Denmark. jlhansen@sund.ku.dk
authors.forename: Jakob L
authors.initials: JL
authors.lastname: Hansen
authors.forename: Jonas T
authors.initials: JT
authors.lastname: Hansen
authors.forename: Tobias
authors.initials: T
authors.lastname: Speerschneider
authors.forename: Christina
authors.initials: C
authors.lastname: Lyngsø
authors.forename: Niels
authors.initials: N
authors.lastname: Erikstrup
authors.forename: Ethan S
authors.initials: ES
authors.lastname: Burstein
authors.forename: David M
authors.initials: DM
authors.lastname: Weiner
authors.forename: Thomas
authors.initials: T
authors.lastname: Walther
authors.forename: Noriko
authors.initials: N
authors.lastname: Makita
authors.forename: Taroh
authors.initials: T
authors.lastname: Iiri
authors.forename: Nicole
authors.initials: N
authors.lastname: Merten
authors.forename: Evi
authors.initials: E
authors.lastname: Kostenis
authors.forename: Søren P
authors.initials: SP
authors.lastname: Sheikh
mesh_terms: D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D019281:Dimerization; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D016234:Kallikrein-Kinin System / Q000502:physiology; D051379:Mice; D041681:NIH 3T3 Cells; D051381:Rats; D044140:Receptor, Angiotensin, Type 1 / Q000235:genetics / Q000378:metabolism*; D043782:Receptor, Bradykinin B2 / Q000235:genetics / Q000378:metabolism*; D012084:Renin-Angiotensin System / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology
chemical_list: D044140:Receptor, Angiotensin, Type 1; D043782:Receptor, Bradykinin B2