title: Tumor necrosis factor-alpha stimulates focal adhesion kinase activity required for mitogen-activated kinase-associated interleukin 6 expression.
abstract: Focal adhesion kinase (FAK) is a cytoplasmic protein-tyrosine kinase that promotes cell migration, survival, and gene expression. Here we show that FAK signaling is important for tumor necrosis factor-alpha (TNFalpha)-induced interleukin 6 (IL-6) mRNA and protein expression in breast (4T1), lung (A549), prostate (PC-3), and neural (NB-8) tumor cells by FAK short hairpin RNA knockdown and by comparisons of FAK-null (FAK(-/-)) and FAK(+/+) mouse embryo fibroblasts. FAK promoted TNFalpha-stimulated MAPK activation needed for maximal IL-6 production. FAK was not required for TNFalpha-mediated nuclear factor-kappaB or c-Jun N-terminal kinase activation. TNFalpha-stimulated FAK catalytic activation and IL-6 production were inhibited by FAK N-terminal but not FAK C-terminal domain overexpression. Analysis of FAK(-/-) fibroblasts stably reconstituted with wild type or various FAK point mutants showed that FAK catalytic activity, Tyr-397 phosphorylation, and the Pro-712/713 proline-rich region of FAK were required for TNFalpha-stimulated MAPK activation and IL-6 production. Constitutively activated MAPK kinase-1 (MEK1) expression in FAK(-/-) and A549 FAK short hairpin RNA-expressing cells rescued TNFalpha-stimulated IL-6 production. Inhibition of Src protein-tyrosine kinase activity or mutation of Src phosphorylation sites on FAK (Tyr-861 or Tyr-925) did not affect TNFalpha-stimulated IL-6 expression. Moreover, analyses of Src(-/-), Yes(-/-), and Fyn(-/-) fibroblasts showed that Src expression was inhibitory to TNFalpha-stimulated IL-6 production. These studies provide evidence for a novel Src-independent FAK to MAPK signaling pathway regulating IL-6 expression with potential importance to inflammation and tumor progression.
authors: Department of Immunology, The Scripps Research Institute, La Jolla, California 92037, USA. dschlaep@scripps.edu
authors: David D
authors: DD
authors: Schlaepfer
authors: Shihe
authors: S
authors: Hou
authors: Ssang-Taek
authors: ST
authors: Lim
authors: Alok
authors: A
authors: Tomar
authors: Honggang
authors: H
authors: Yu
authors: Yangmi
authors: Y
authors: Lim
authors: Dan A
authors: DA
authors: Hanson
authors: Sean A
authors: SA
authors: Uryu
authors: John
authors: J
authors: Molina
authors: Satyajit K
authors: SK
authors: Mitra
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D004789:Enzyme Activation; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D011392:Proline / Q000378:metabolism; D034622:RNA Interference; D015398:Signal Transduction / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D015850:Interleukin-6; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D014443:Tyrosine; D011392:Proline; D051416:Focal Adhesion Protein-Tyrosine Kinases; D019061:src-Family Kinases; D020928:Mitogen-Activated Protein Kinases