Requirement of Smad3 for mast cell growth

• Published in: Cellular Immunology Vol. 240; no. 1; pp. 47 - 52
• Main Authors: Funaba, Masayuki, Nakaya, Kohei, Ikeda, Teruo, Murakami, Masaru, Tsuchida, Kunihiro, Sugino, Hiromu
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.03.2006
• Subjects: Activin; Activins - metabolism; Animals; Bone Marrow Cells - cytology; Cell Cycle; Cell Division; Cell growth; Cells, Cultured; Culture Media, Conditioned; Gene Expression Regulation; Inhibin-beta Subunits - metabolism; Mast cells; Mast Cells - cytology; Mast Cells - metabolism; Mice; Mice, Inbred C57BL; Proto-Oncogene Proteins c-kit - genetics; Receptors, IgE - genetics; RNA, Messenger - genetics; RNA, Messenger - metabolism; Smad3; Smad3 Protein - deficiency; Smad3 Protein - genetics; Smad3 Protein - metabolism; Tetrazolium Salts - metabolism; TGF-β; Thiazoles - metabolism; Transforming Growth Factor beta - metabolism; TGF-β; Smad3; Cell growth; Mast cells; Activin
• ISSN: 0008-8749; 1090-2163; 1365-2567
• DOI: 10.1016/j.cellimm.2006.06.002

The involvement of the TGF-β family in cell growth of bone marrow-derived mast cells (BMMC) cultured with medium containing pokeweed mitogen-stimulated spleen cell-conditioned medium (PWM-SCM) was examined. Doubling time of BMMC from Smad3-null mice was longer than that from wild-type (WT) mice, and the differences tended to be larger with time of culture. Consistent with the results, uptake and reduction of [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2 H-tetrazolium, inner salt; MTS] was lower in Smad3-deficient BMMC. Cell cycle analyses revealed no apparent differences between WT BMMC and Smad3-deficient BMMC, suggesting that longer doubling time in Smad3-deficient BMMC resulted from increased cell death. TGF-β and activin A were supplied by PWM-SCM rather than by self-production by BMMC. Blocking the TGF-β pathway by anti-TGF-β neutralizing antibody or an inhibitor for the type I receptors for ligands including TGF-β and activin, SB431542, inhibited MTS uptake and reduction in WT BMMC, whereas anti-activin A antibody and SB431542 tended to inhibit them in Smad3-deficient BMMC. The present results suggest that TGF-β-induced and Smad3-mediated signaling is essential for maximal cell growth in mast cells, and that the activin pathway may be required for it when mast cell context is modulated by Smad3 depletion.