Integrin-mediated Tyrosine Phosphorylation and Cytokine Message Induction in Monocytic Cells
A POSSIBLE SIGNALING ROLE FOR THE Syk TYROSINE KINASE (*)
- Tsung H. Lin(1),
- Carlos Rosales(1),
- Krishna Mondal(2),
- Joseph B. Bolen(4),
- Stephen Haskill(2)(3) and
- Rudy L. Juliano(1)(§)
- From the (1) Department of Pharmacology, the
- (2)Department of Microbiology and Immunology, and
- (3)Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, and the
- (4)Department of Molecular Biology, The Bristol-Myers Squibb Pharmaceutical Research Institute, Princeton, New Jersey 08543
- § To whom correspondence should be addressed: Dept. of Pharmacology, University of North Carolina, CB 7365, Chapel Hill, NC 27599. Tel.: 919-966-4383; Fax: 919-966-5640.
Abstract
Activation of cytoplasmic tyrosine kinases is an important aspect of signal transduction mediated by integrins. In the human
monocytic cell line THP-1, either integrin-dependent cell adhesion to fibronectin or ligation of β1 integrins with antibodies
causes a rapid and intense tyrosine phosphorylation of two sets of proteins of about 65-75 and 120-125 kDa. In addition, integrin
ligation leads to nuclear translocation of the p50 and p65 subunits of the NF-κB transcription factor, to activation of a
reporter gene driven by a promoter containing NF-κB sites, and to increased levels of mRNAs for immediate-early genes, including
the cytokine interleukin (IL)-1β. The tyrosine kinase inhibitors genistein and herbimycin A block both integrin-mediated tyrosine
phosphorylation and increases in IL-1β message levels, indicating a causal relationship between the two events. The components
tyrosine phosphorylated subsequent to cell adhesion include paxillin, pp125
, and the SH2 domain containing tyrosine kinase Syk. In contrast, integrin ligation with antibodies induces tyrosine phosphorylation
of Syk but not of FAK or paxillin. In adhering cells, pre-treatment with cytochalasin D suppresses tyrosine phosphorylation
of FAK and paxillin but not of Syk, while IL-1β message induction is unaffected. These observations indicate that the Syk
tyrosine kinase may be an important component of an integrin signaling pathway in monocytic cells, leading to activation of
NF-κB and to increased levels of cytokine messages.
Footnotes
-
↵* This work was supported by grants from the National Institutes of Health (to S. H. and R. L. J.) and by a grant from the American Cancer Society (to R. L. J.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵1 The abbreviations are:
- FAK
-
focal adhesion kinase
- BSA
-
bovine serum albumin
- ECM
-
extracellular matrix
- IL
-
interleukin
- PAGE
-
polyacrylamide gel electrophoresis
- PBS
-
phosphate-buffered saline
- CAT
-
chloramphenicol acetyltransferase
- EMSA
-
electrophoretic mobility shift assay.
-
↵2 Lofquist, A. K., Mondal, K., Morris, J. S., and Haskill, J. S. (1995) Mol. Cell. Biol.15, 1737-1746.
