Functional characterization of corticotropin-releasing factor type 1 receptor endogenously expressed in human embryonic kidney 293 cells

The endogenous expression in human embryonic kidney 293 (HEK293) cells of c orticotropin-releasing factor (CRF) receptors was detected. High-affinity b inding sites for human CRF (K-i = 3.6 nM), ovine CRF (K-i = 4.6 nM), rat ur ocortin ( K-i = 2.2 nM), sauvagine (K-i = 2.4 nM) and astressin (K-i = 4.3 nM) with the pharmacological characteristics for CRF type 1 (CRF1) receptor s and B-max values of similar to 30 fmol/mg protein were determined. The fo ur CRF receptor agonists nonselectively stimulated cAMP production in HEK29 3 cells at low agonist concentrations, whereas the antagonist astressin shi fted the dose-response curve for ovine CRF significantly rightward. Transfe ction of the pcDNA3 Vector into HEK293 cells strongly reduced the expressio n of the endogenous CRF receptor. Northern blot analysis revealed the expre ssion of a CRF1 transcript in human neuronal tissues, HEK293, human NTera-2 (NT2) carcinoma, Y-79 retinoblastoma and African green monkey kidney (COS- 7) cells. Neither by Northern blot analysis nor by reverse transcriptase PC R (RT-PCR), the expression of CRF2 could be detected. In cAMP stimulation e xperiments, functional CRF receptors were detected in these cell lines. The se data show that HEK293 and other cell lines endogenously express CRF1 rec eptors. (C) 2000 Elsevier Science B.V. All rights reserved.