Regulation of inducible bradykinin B1 receptor gene expression through absence of internalization and resensitization.
Rapid induction and down-regulation of bradykinin B1 receptor (BKB1R) gene expression is tightly regulated at the transcriptional and mRNA levels (Zhou et al. [1998] Biochem. J. 330:361-366; Zhou et al. [1999] Mol. Cell Biol. Res. Commun. 1:29-35). Here we explore regulation of BKB1R expression at the protein level. To make this inducible gene express constitutively, we utilized a bicistronic mammalian expression vector (pCMin) for stable transfection of the BKB1R gene into human lung fibroblasts, IMR90SV40. The BKB1R displayed a high affinity and specificity (K(d) = 0.5 nM) for desArg(10)-kallidin. The receptor mediated such signaling events as arachidonic acid (ARA) release, phosphoinositide (PI) turnover and Ca(2+)-flux. The receptor function proved differentially desensitized. For example, after initial exposure to desArg(10)-kallidin, a second stimulation with desArg(10)-kallidin did not induce further Ca(2+)-flux or ARA-release while PI-turnover continued unabated. Unlike most of the G-protein coupled receptors, the BKB1R did not internalize within 60 min of exposure to 10 nM desArg(10)-kallidin. It also did not resensitize. Thus, the duration and signal capacity of the BKB1R at the protein level is regulated through lack of internalization, an absence of resensitization and a lack of desensitization for certain events such as PI turnover. In fact, the absence of BKB1R resensitization is likely a very important contributor to the rapid disappearance of this inducible receptor.
Zhou
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Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA.
Prado
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Taylor
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Yang
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Polgar
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D016718:Arachidonic Acid / Q000378:metabolism; D015152:Blotting, Northern; D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D017931:DNA Primers / Q000737:chemistry; D004705:Endocytosis; D005347:Fibroblasts / Q000378:metabolism; D005786:Gene Expression Regulation; D005822:Genetic Vectors; D006801:Humans; D007609:Kallidin / Q000031:analogs & derivatives* / Q000494:pharmacology; D008168:Lung / Q000166:cytology / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism; D043783:Receptor, Bradykinin B1; D043782:Receptor, Bradykinin B2; D018002:Receptors, Bradykinin / Q000096:biosynthesis* / Q000235:genetics*; D014162:Transfection
D017931:DNA Primers; D010716:Phosphatidylinositols; D043783:Receptor, Bradykinin B1; D043782:Receptor, Bradykinin B2; D018002:Receptors, Bradykinin; D016718:Arachidonic Acid; D007609:Kallidin; C052787:kallidin, des-Arg(10)-; D001920:Bradykinin; D002118:Calcium