Requirement of Smad3 for mast cell growth.
The involvement of the TGF-beta 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)-2H-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-beta and activin A were supplied by PWM-SCM rather than by self-production by BMMC. Blocking the TGF-beta pathway by anti-TGF-beta neutralizing antibody or an inhibitor for the type I receptors for ligands including TGF-beta 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-beta-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.
Funaba
Masayuki
M
Laboratory of Nutrition, Azabu University School of Veterinary Medicine, 1-17-71 Fuchinobe, Sagamihara, Japan. funaba@azabu-u.ac.jp
Nakaya
Kohei
K
Ikeda
Teruo
T
Murakami
Masaru
M
Tsuchida
Kunihiro
K
Sugino
Hiromu
H
D028341:Activins / Q000378:metabolism; D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D002453:Cell Cycle; D002455:Cell Division; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D005786:Gene Expression Regulation; D028322:Inhibin-beta Subunits / Q000378:metabolism; D008407:Mast Cells / Q000166:cytology* / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017455:Receptors, IgE / Q000235:genetics; D051900:Smad3 Protein / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D013778:Tetrazolium Salts / Q000378:metabolism; D013844:Thiazoles / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism
D017077:Culture Media, Conditioned; D012333:RNA, Messenger; D017455:Receptors, IgE; D051900:Smad3 Protein; D013778:Tetrazolium Salts; D013844:Thiazoles; D016212:Transforming Growth Factor beta; C422405:activin A; D028341:Activins; C070380:3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium; D028322:Inhibin-beta Subunits; D019009:Proto-Oncogene Proteins c-kit