Mechanical stimulation activates Gαq signaling pathways and 5-hydroxytryptamine release from human carcinoid BON cells
Minsoo Kim, … , Fievos Christofi, Helen J. Cooke
Minsoo Kim, … , Fievos Christofi, Helen J. Cooke
Published October 1, 2001
Citation Information: J Clin Invest. 2001;108(7):1051-1059. https://doi.org/10.1172/JCI12467.
View: Text | PDF
Article

Mechanical stimulation activates Gαq signaling pathways and 5-hydroxytryptamine release from human carcinoid BON cells

Abstract

5-Hydroxytryptamine (5-HT) released from enterochromaffin cells activates secretory and peristaltic reflexes necessary for lubrication and propulsion of intestinal luminal contents. The aim of this study was to identify mechanosensitive intracellular signaling pathways that regulate 5-HT release. Human carcinoid BON cells displayed 5-HT immunoreactivity associated with granules dispersed throughout the cells or at the borders. Mechanical stimulation by rotational shaking released 5-HT from BON cells or from guinea pig jejunum during neural blockade with tetrodotoxin. In streptolysin O–permeabilized cells, guanosine 5′-O- (2-thiodiphosphate) (GDP-β-S) and a synthetic peptide derived from the COOH terminus of Gαq abolished mechanically evoked 5-HT release, while the NH2-terminal peptide did not. An antisense phosphorothioated oligonucleotide targeted to a unique sequence of Gαq abolished mechanically evoked 5-HT release and reduced Gαq protein levels without affecting the expression of Gα11. Depletion and chelation of extracellular calcium did not alter mechanically evoked 5-HT release, whereas depletion of intracellular calcium stores by thapsigargin and chelation of intracellular calcium by 1,2-bis (o-Aminophenoxy) ethane-N,N,N′,N′-tetraacetic acid tetra (acetoxymethyl) ester (BAPTA-AM) reduced 5-HT release. Mechanically evoked 5-HT release was inhibited by somatostatin-14 in a concentration-dependent manner. The results suggest that mechanical stimulation of enterochromaffin-derived BON cells directly or indirectly stimulates a G protein–coupled receptor that activates Gαq, mobilizes intracellular calcium, and causes 5-HT release.

Authors

Minsoo Kim, Najma H. Javed, Jun-Ge Yu, Fievos Christofi, Helen J. Cooke

×

Figure 1

Options: View larger image (or click on image) Download as PowerPoint
Transmission electron micrographs of BON cells. Sections (80 nm) were ex...
Transmission electron micrographs of BON cells. Sections (80 nm) were examined with a Philips CM 12 transmission electron microscope at 60 kV. (a and b) Electron micrographs showing microvilli with varying shapes and sizes on the plasma membrane of BON cells. Note abundance of granules adjacent to microvilli (b). (c) Bottom surface has no microvilli-like protrusions. (d) The cytoplasm is rich in secretory granules. Scale bar, 1 μm. ×7,500 (b); ×12,500 (d); ×70,000 (a and c).