|Torfs, Herbert - ZOOLOGICAL INST. LEUVEN|
|Shariatmadari, Ramin - UPPSALA UNIV. SWEDEN|
|Parmentier, Marc - IRIBHN ULB, BRUSSELS|
|Poels, Jeron - ZOOLOGICAL INST LEUVEN|
|Van Poyer, Wendy - ZOOLOGICAL INST. LEUVEN|
|Swinnen, Elfriede - ZOOLOGICAL INST. LEUVEN|
|DE Loof, Arnold - ZOOLOGICAL INST. LEUVEN|
|Ackerman, Karl - UPPSALA UNIV. SWEDEN|
|Vanden Broeck, Jozef - ZOOLOGICAL INST. LEUVEN|
Submitted to: Journal of Neurochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 7, 2000
Publication Date: N/A
Interpretive Summary: Tachykinins are members of a family of peptides demonstrated to act as neurohormones in mammals and invertebrates, including insects. In conjunction with their respective receptors, these peptide hormones appear critical to a number of motor and sensory functions, particularly related to central and peripheral neuron activity and the contraction of smooth muscle. STKR (for Stable fly Tachykinin Receptor) is a 4118 bp clone from a stable fly, Stomoxys calcitrans, cDNA library which encodes a protein with significant amino acid similarity to tachykinin-like peptide receptors in other organisms. Functional expression of the cloned STKR was obtained in cultured insect cells. The STKR-expressing cell line was used to study the interactions of STKR with various chemicals and peptides which are known to interact with tachykinin receptors. The aim is to identify substances which inhibit or promote cellular responses relying on STKR which are critical to the stable fly.
Technical Abstract: STKR is an insect G protein-coupled receptor, cloned from the stable fly Stomoxys calcitrans. It displays sequence similarity to vertebrate tachykinin [or neurokinin (NK)] receptors. Functional expression of the cloned STKR cDNA was obtained in cultured Drosophila melanogaster Schneider 2 (S2) cells. Insect tachyknin-like peptides or "insectatachykinins," such has Locusta tachykinin (Lom-TK) III, produced dose-dependent calcium responses in stably transfected S2-STK cells. Vertebrate tachykinins (or neurokinins) did not evoke any effect at concentrations up to 10-5M, but an antogonist of mammalian neurokinin receptors, spantide II, inhibited the Lom-TK III-induced calcium response. Further analysis showed that the agonist-induced intracellular release of calcium ions was not affected by the pretreatment of the cells with pertussis toxin. The calcium rise was blocked by the phospholipase C inhbitor U73122. In addition, Lom-TK III was shown to have a stimulatory effect on the accumulation of both inosito 1,4,5-trisphosphate and cyclic AMP. These are the same second messengers that are induced in mammalian neurokinin-dependent signaling processes.