title: Novel regulatory effect of angiotensin II type 1 receptor-interacting molecule on vascular smooth muscle cells.
abstract: We have recently cloned a novel molecule that interacts with the angiotensin II type 1 receptor (AT1R)-associated protein (ATRAP). In this study, we tested the hypothesis that ATRAP modulates angiotensin II-induced responses in vascular smooth muscle cells. The results of immunoprecipitation and bioluminescence resonance energy transfer assay demonstrated a direct interaction between ATRAP and AT1R at baseline and showed that angiotensin II enhanced the interaction of these proteins >2-fold. The results of immunofluorescence analysis also demonstrated that >65% of ATRAP constitutively colocalized with an endosome marker. Although only 36% of ATRAP colocalized with AT1R at baseline, angiotensin II enhanced the colocalization of these molecules and made 92% of ATRAP colocalize with AT1R on a quantitative fluorescence analysis. Overexpression of ATRAP by adenoviral transfer decreased the cell surface AT1R number from 4.33 to 2.13 fmol/10(6) cells at baseline and from 3.04 to 1.26 fmol/10(6) cells even after removal of angiotensin II. ATRAP also suppressed angiotensin II-mediated increases in c-fos gene transcription and transforming growth factor-beta production. Furthermore, this suppression was accompanied by inhibition of angiotensin II-induced activation of 5-bromodeoxyuridine incorporation. Finally, ATRAP knockdown by small-interference RNA activated angiotensin II-induced c-fos gene expression, which was effectively inhibited by valsartan, an AT1R-specific antagonist. These results indicate that ATRAP promotes internalization of AT1R and attenuates the angiotensin II-mediated c-fos-transforming growth factor-beta pathway and proliferative response in vascular smooth muscle cells, suggesting a novel strategy to inhibit vascular fibrosis and remodeling through a novel and specific blockade of AT1R signaling.
authors: Department of Cardiorenal Medicine, Yokohama City University School of Medicine, Yokohama, Japan.
authors: Koichi
authors: K
authors: Azuma
authors: Kouichi
authors: K
authors: Tamura
authors: Atsu-ichiro
authors: A
authors: Shigenaga
authors: Hiromichi
authors: H
authors: Wakui
authors: Shin-ichiro
authors: S
authors: Masuda
authors: Yuko
authors: Y
authors: Tsurumi-Ikeya
authors: Yutaka
authors: Y
authors: Tanaka
authors: Masashi
authors: M
authors: Sakai
authors: Miyuki
authors: M
authors: Matsuda
authors: Tatsuo
authors: T
authors: Hashimoto
authors: Tomoaki
authors: T
authors: Ishigami
authors: Marco
authors: M
authors: Lopez-Ilasaca
authors: Satoshi
authors: S
authors: Umemura
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D031541:Fluorescence Resonance Energy Transfer; D018014:Gene Transfer Techniques; D047468:Immunoprecipitation; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D011485:Protein Binding; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D044140:Receptor, Angiotensin, Type 1 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D011945:Receptors, Angiotensin / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013777:Tetrazoles / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects; D014633:Valine / Q000031:analogs & derivatives / Q000494:pharmacology; D000068756:Valsartan
chemical_list: C524087:Agtrap protein, rat; D047228:Angiotensin II Type 1 Receptor Blockers; D016760:Proto-Oncogene Proteins c-fos; D034741:RNA, Small Interfering; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin; D013777:Tetrazoles; D000804:Angiotensin II; D000068756:Valsartan; D014633:Valine