TGF-beta1 modifications in nuclear matrix proteins of osteoblasts during differentiation
Graduate School of Biomedical Sciences; Department of Cell Biology and Cancer Center
Medical Subject Headings
Animals; Antigens, Nuclear; *Cell Differentiation; Electrophoresis, Gel, Two-Dimensional; Extracellular Matrix; Nuclear Proteins; Osteoblasts; Rats; Rats, Sprague-Dawley; Transforming Growth Factor beta
Life Sciences | Medicine and Health Sciences
Nuclear matrix protein (NMP) composition of osteoblasts shows distinct two-dimensional gel electrophoretic profiles of labeled proteins as a function of stages of cellular differentiation. Because NMPs are involved in the control of gene expression, we examined modifications in the representation of NMPs induced by TGF-beta1 treatment of osteoblasts to gain insight into the effects of TGF-beta on development of the osteoblast phenotype. Exposure of proliferating fetal rat calvarial derived primary cells in culture to TGF-beta1 for 48 h (day 4-6) modifies osteoblast cell morphology and proliferation and blocks subsequent formation of mineralized nodules. Nuclear matrix protein profiles were very similar between control and TGF-beta-treated cultures until day 14, but subsequently differences in nuclear matrix proteins were apparent in TGF-beta-treated cultures. These findings support the concept that TGF-beta1 modifies the final stage of osteoblast mineralization and alters the composition of the osteoblast nuclear matrix as reflected by selective and TGF-beta-dependent modifications in the levels of specific nuclear matrix proteins. The specific changes induced by TGF-beta in nuclear matrix associated proteins may reflect specialized mechanisms by which TGF-beta signalling mediates the alterations in cell organization and nodule formation and/or the consequential block in extracellular mineralization.
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Citation: J Cell Biochem. 1998 Jun 1;69(3):291-303.