Substance P-stimulated interleukin-8 expression in human colonic epithelial cells involves Rho family small GTPases.
Interaction of the neuropeptide substance P (SP) and its neurokinin-1 receptor (NK-1R) plays an important role in the pathophysiology of intestinal inflammation. SP is known to stimulate production of interleukin (IL)-6 and IL-8 in the U-373-MG human astrocytoma cell line via activation of p38 MAPK (mitogen-activated protein kinase) and nuclear factor (NF)-kappaB, respectively. However, the signalling mechanisms by which SP-NK-1R interaction induces NF-kappaB activation and IL-8 expression are still not clear. In this study we demonstrate that SP stimulates IL-8 secretion and IL-8 promoter activity in the NCM460 non-transformed human colonic epithelial cell line transfected with NK-1R cDNA. Our results indicate that inhibition of endogenous Rho family proteins (RhoA, Rac1 and Cdc42) by their respective dominant negative mutants significantly decreases SP-induced IL-8 secretion and IL-8 promoter activity. We also demonstrate that SP rapidly activates RhoA, Rac1 and Cdc42 and that co-expression of the dominant negative mutants of RhoA, Rac1 and Cdc42 in NK-1R cDNA-transfected NCM460 cells significantly inhibits SP-induced NF-kappaB-dependent gene expression. These results demonstrate that Rho family small GTPases RhoA, Rac1 and Cdc42 are novel signal transducers for SP-stimulated IL-8 expression.
Zhao
Dezheng
D
Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, U.S.A.
Kuhnt-Moore
Sabina
S
Zeng
Huiyan
H
Pan
Amy
A
Wu
Jack S
JS
Simeonidis
Simos
S
Moyer
Mary P
MP
Pothoulakis
Charalabos
C
D002478:Cells, Cultured; D003106:Colon / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005799:Genes, Dominant; D006801:Humans; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism*; D016328:NF-kappa B / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D018040:Receptors, Neurokinin-1 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D027602:Serum Response Element / Q000187:drug effects; D015398:Signal Transduction; D013373:Substance P / Q000378:metabolism / Q000494:pharmacology*; D020764:cdc42 GTP-Binding Protein / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*
D016209:Interleukin-8; D016328:NF-kappa B; D018040:Receptors, Neurokinin-1; D013373:Substance P; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein