Signal transduction mechanisms of recombinant bovine neurokinin-2 receptor stably expressed in Baby hamster kidney cells
✍ Scribed by Harald R. Eistetter; Ann Mills; Stephen J. Arkinstall
- Publisher
- John Wiley and Sons
- Year
- 1993
- Tongue
- English
- Weight
- 705 KB
- Volume
- 52
- Category
- Article
- ISSN
- 0730-2312
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✦ Synopsis
The bovine neurokinin-2 (NK-2) receptor gene was stably transfected into Baby hamster kidney (BHK-21) fibroblasts and one recombinant clone expressing 17,700 high-affinity ['2sl]neurokinin A (NKA) binding sites/cell characterized further. [1251]NKA binding was displaced by unlabeled NKA with an IC5" of 8.26 * 2 n M (n = 5) and with the rank order of potency NKA > neurokinin B (NKB) > Substance P (SP) confirming pharmacological characteristics of an NK-2 receptor subtype. Stimulation with NKA resulted in a rapid and dose-dependent increase in inositol 1,4,5-trisphosphate (IP3) levels (ECsO = 32 ? 10 nM; n = 7) which was paralleled bya transient biphasic rise in intracellular free calcium concentration [Ca2+], (EC50 = 35 ? 20 nM; n = 3). In addition to phosphoinositide (PI) hydrolysis and Ca2+ mobilization, NKA was found to stimulate both cyclicAMP formation (EC5" = 1.02 ? 0.26 p,M; n = 7) and [3H]arachidonic acid mobilization (EC50 = 0.65 * 0.45 p,M; n = 4). Interestingly, cyclicAMP levels also rose after addition of an exogenous arachidonic acid metabolite, prostaglandin E2 (PGE2) (EC50 = 11.5 ? 2 kM). Similar observations of NKA-induced IP3 production, Ca2+ mobilization, arachidonic acid liberation, and CAMP formation have been made previously following expression of the bovine NK-2 receptor in Chinese hamster ovary (CHO) epithelial cells. The present results suggest that activation of NK-2 receptors leads to characteristic and reproducible intracellular second messenger responses in a subclass of cell types which includes fibroblasts and epithelial cells irrespective of their genetic and phenotypic background.