THE B-1-AGONIST [DES-ARG(10)]-KALLIDIN ACTIVATES TRANSCRIPTION FACTORNF-KAPPA-B AND INDUCES HOMOLOGOUS UP-REGULATION OF THE BRADYKININ B-1-RECEPTOR IN CULTURED HUMAN LUNG FIBROBLASTS
Jp. Schanstra et al., THE B-1-AGONIST [DES-ARG(10)]-KALLIDIN ACTIVATES TRANSCRIPTION FACTORNF-KAPPA-B AND INDUCES HOMOLOGOUS UP-REGULATION OF THE BRADYKININ B-1-RECEPTOR IN CULTURED HUMAN LUNG FIBROBLASTS, The Journal of clinical investigation, 101(10), 1998, pp. 2080-2091
The bradykinin beta(1)-receptor is strongly upregulated under chronic
inflammatory conditions. However, the mechanism and reason are not kno
wn. Because a better understanding of the mechanism of the upregulatio
n will help in understanding its potential importance in inflammation,
we have studied the molecular mechanism of beta(1)-receptor upregulat
ion in cultured human lung fibroblasts (IMR 90) in response to IL-1 be
ta and the B-1-agonist [des-Arg(10)]-kallidin. We show that treatment
of human IMR 90 cells by IL-1 beta stimulates the expression of both B
-1-receptor mRNA and protein. The latter was studied by Western blot a
nalysis using antipeptide antibodies directed against the COOH-termina
l part of the human B-1-receptor. We furthermore report the novel obse
rvation that the B-1-receptor is upregulated by its own agonist which
was completely blocked by the specific B-1-antagonist [des-Arg(10)-Leu
(9)]-kallidin, indicating an upregulation entirely mediated through ce
ll surface B-1-receptors. The increased population of B-1-receptors wa
s functionally coupled as exemplified by an enhancement of the B-1-ago
nist induced increase in free cytosolic calcium. Upregulation by the B
-1-agonist was blocked by a specific protein kinase C inhibitor. B-1-a
gonist-induced upregulation was correlated to the induction of transcr
iption factor nuclear factor kappa B (NF-kappa B) which efficiently bo
und to the NF-kappa B-Like sequence located in the promoter region of
the human B-1-receptor gene. This correlation was further confirmed by
reporter gene assays which showed that this NF-kappa B-like sequence,
in the B-1-receptor promoter context, could contribute to IL-1 beta a
nd DLBK-induced B-1-receptor transcription activation, and by the effe
ct of NF-kappa B inhibitor pyrrolidinedithiocarbamate which diminished
both B-1-receptor upregulation and NF-kappa B activation. NF-kappa B
is now recognized as a key inflammatory mediator which is activated by
the B-1-agonist but which is also involved in B-1-receptor upregulati
on.