Growth Factors and Signaling in Development:
CSF-1 Biology: Colony stimulating factor-1 (CSF-1) is a growth factor which regulates the production of mononuclear phagocytes, Langerhans cells, osteoclasts, and the function of certain non-mononuclear phagocytic cell types in the female reproductive tract. It is expressed as a secreted glycoprotein, secreted proteoglycan or a membrane-spanning, cell-surface glycoprotein. Its effects are mediated via a receptor tyrosine kinase, the c-fms protooncoprotein (1). CSF-1-deficient mice are osteopetrotic due to a lack of osteoclasts, have poor fertility and several other defects related to CSF-1 regulation of macrophages that have critical scavenger and trophic roles in the development, maintenance or function of tissues in which they reside. The developmental and physiological roles of CSF-1 are being studied using CSF-1- and CSF-1R-deficient mice, coupled with transgenic approaches (2-7). CSF-1 regulation of macrophages is also important in innate immunity, inflammatory diseases, atherosclerosis, obesity and within tumors, for tumor progression and metastasis (8). For example, CSF-1 regulation of tumor associated macrophages enhances tumor progression of solid tumors (9). Mouse genetic and other approaches are being taken to investigate the role of the CSF-1 isoforms in disease development.
CSF-1 signal transduction: Since phosphorylation of specific CSF-1R intracellular domain tyrosine residues initiate particular signaling pathways, detailed structure-function studies of the CSF-1R are being carried out in macrophages and macrophage progenitor cells. In the analysis of very early post-receptor events, proteins that are rapidly phosphorylated in tyrosine in response to CSF-1 or associated with tyrosine phosphorylated proteins, approximately 150 in all, have been identified by mass spectrometry. A combination of genetic, proteomic, biochemical and analytical imaging approaches are being used to elucidate the roles and interactions of these signaling proteins in the immediate post-receptor events in CSF-1 signal transduction (10). Among the proteins studied are: The protein tyrosine phosphatase SHP-1, that negatively affects cell survival in the absence of CSF-1 (11). The cbl proto-oncogene product, that negatively regulates CSF-1 proliferation signaling by enhancing CSF-1R endocytosis (12,13). The macrophage F-actin associated and tyrosine phosphorylated protein (MAYP), that regulates the actin cytoskeleton (14) and mutations in which lead to autoinflammatory disease (15). Doks-1, -2 and -3, that regulate signaling and motility and protein tyrosine phosphatase, PTP-phi, that mediates CSF-1-induced morphological changes, adhesion and motility, via its action on a specific substrate, paxillin (16,17).
Signaling by the Shark tyrosine kinase: Embryonic dorsal closure in Drosophila is a series of morphogenetic movements involving the bilateral dorsal movement of the epidermis (cell stretching) and dorsal suturing of the leading edge cells to enclose the viscera. The Syk family tyrosine kinase, Shark, is expressed in the epidermis and plays a crucial role in this Jun kinase-dependent process, where it acts upstream of JNK in
leading edge cells (18,19). Mutations in the genes for shark gene and Shark-interacting proteins (20), coupled with cell biological approaches are being used to define Shark function and the Shark signaling pathways.
1. Pixley, F.J. and Stanley, E.R. (2004) CSF-1 Regulation of the Wandering Macrophage: Complexity in action. Trends in Cell Biol. 14:628-638.
2. Ryan, G.R., Dai, X-M., Dominguez, M., Tong, W., Chuan, F., Chisholm, O., Russell, R.G., Pollard, J.W. and Stanley, E.R. (2001) Rescue of the Colony Stimulating Factor 1 (CSF-1) nullizygous mouse (Csf1op/Csf1op) phenotype with a CSF-1 transgene and identification of sites of local CSF-1 synthesis. Blood 98:74-84.
3. Dai, X-M., Ryan, G.R., Hapel, A.J., Dominguez, M.G., Kapp, S., Sylvestre, V. and Stanley, E.R. (2001) Targeted disruption of the mouse CSF-1 receptor gene results in osteopetrosis, mononuclear phagocyte deficiency, increased splenic progenitor cell frequencies and reproductive defects. Blood 99:111-120.
4. Dai X-M, Zong XH, Sylvestre V and Stanley ER. (2004) Incomplete restoration of colony stimulating factor-1 (CSF-1) function in CSF-1-deficient Csf1op/Csf1op mice by transgenic expression of cell surface CSF-1. Blood 103: 1114-1123.
5. Dai, X-M., Zong, X., Akhter, M.P. and Stanley, E.R. (2004) Osteoclast deficiency results in disorganized matrix, reduced mineralization and abnormal osteoblast behavior in developing bone. J. Bone Min. Res. 19: 1441-1451.
6. Nandi, S., Akhter, M.P., Seifert, M.F., Dai, X-M. and Stanley, E.R. (2006) Developmental and functional significance of the CSF-1 proteoglycan chondroitin sulfate chain. Blood 107:786-795.
7. Ginhoux, F., Tacke, F., Angeli, V., Bogunovic, M., Loubeau, M., Dai, X-M., Stanley, E.R., Randolph, G.J., Merad, M. (2006). Langerhans cells arise from monocytes in vivo. Nature Immunology 7:265-273.
8. Chitu, V. and Stanley, E.R. (2006) Colony stimulating factor-1 in immunity and inflammation. Current Opinion in Immunology 18:39-48.
9. Paulus, P., Stanley, E.R., Schäfer, R., Abraham, D. and Aharinejad, S. (2006). CSF-1 antibody reverses chemoresistance in human MCF-7 breast cancer xenografts. Cancer Research 66:4349-4356.
10. Yeung, Y-G. and Stanley, E.R. (2003) Proteomic approaches to analysis of the early events in CSF-1 signal transduction. Molecular and Cellular Proteomics. 2: 1143-1155.
11. Berg, K.L., Siminovitch, K.A. and Stanley, E.R. (1999) SHP-1 regulation of p62DOK tyrosine phosphorylation in macrophages. J. Biol. Chem. 274:35855-35865.
12. Wang, Y., Yeung, Y.G., Langdon, W.Y. and Stanley, E.R. (1996) c-Cbl Is Transiently Tyrosine phosphorylated, Ubiquitinated, and Membrane-targeted following CSF-1 Stimulation of Macrophages. J. Biol. Chem. 271:17-20.
13. Lee, P.S.W., Wang, Y., Dominguez, M.G., Yeung, Y-G., Murphy, M.A. Bowtell, D.D.L. and Stanley, E.R. (1999) The Cbl protooncoprotein stimulates CSF-1 receptor multiubiquitination and endocytosis, and attenuates macrophage proliferation. EMBO J. 18:3616-3628.
14. Chitu, V., Pixley, F.J., Yeung, Y.G., Macaluso, F., Condeelis, J. and Stanley, E.R. (2005). The PCH family member MAYP/PSTPIP2 directly regulates F-actin bundling and enhances filopodia formation and motility in macrophages. Mol. Biol. Cell. 16:2947-2959.
15. Grosse, J., Chitu, V., Marquardt, A., Hanke, P., Schmittwolf, C., Zeitlmann, L., Schropp, P., Barth, B., Yu, P., Paffenholz, R., Stumm, G., Nehls, M. and Stanley, E.R. (2006) Mutation of mouse MAYP/PSTPIP2 causes a macrophage autoinflammatory disease. Blood 107:3350-3358.
16. Pixley, F.J., Lee, P.S.W., Dominguez, M.G., Einstein, D.B. and Stanley, E.R. (1995) A heteromorphic protein tyrosine phosphatase, PTPphi, is regulated by CSF-1 in macrophages. J. Biol. Chem. 270:27339-27347.
17. Pixley, F.J., Lee, P.S.W., Condeelis, J. and Stanley, E.R. (2001) Protein tyrosine phosphatase phi regulates paxillin tyrosine phosphorylation and mediates Colony Stimulating Factor 1 induced morphological changes in macrophages. Mol. Cell. Biol. 21:1795-1809.
18. Ferrante, Jr., A.W, Reinke, R. and Stanley, E.R. (1995) Shark, a Src homology 2, ankyrin repeat, tyrosine kinase expressed on the apical surfaces of ectodermal epithelia. Proc. Natl. Acad. Sci. USA 92:1911-1915.
19. Fernandez, R., Takahashi, F., Liu, Z., Steward, R., Stein, D. and Stanley, E.R. (2000) The Drosophila Shark tyrosine kinase is required for embryonic dorsal closure. Genes and Development 14:604-614.
20. Biswas, R., Stein, D. and Stanley, E.R. (2006) Drosophila Dok is required for embryonic dorsal closure. Development 133:217-227.