Effects of dexamethasone on the expression of transforming growth factor-beta in mouse embryonic palatal mesenchymal cells. 1996

M Potchinsky, and P Nugent, and C Lafferty, and R M Greene
Daniel Baugh Institute, Department of Pathology, Anatomy, and Cell Biology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.

The central role of TGF-beta in the development of the embryonic palate has been well characterized. TGF-beta inhibits mesenchymal cell proliferation, induces medial edge epithelial cell differentiation, and modulates the expression of extracellular matrix proteins as well as the proteases that act upon them. Mechanisms by which TGF-beta expression itself is regulated are less well understood. Glucocorticoids are recognized in several cellular systems as able to regulate the expression of TGF-beta. This study was therefore designed to examine whether glucocorticoids affect the expression of TGF-beta isoforms in embryonic palatal cells. Based on flow cytometric analysis and viability determination, confluent primary cultures of mouse embryonic palate mesenchymal (MEPM) cells exposed to up to 10(-6) M dexamethasone (dex) exhibited no signs of cytotoxicity after 24 hours of exposure. Northern blot analyses revealed that dexamethasone reduced steady-state mRNA levels of TGF-beta 3 in a dose-dependent manner as early as 4 hours after treatment but had little effect on TGF-beta 1 and TGF-beta 2 expression up to 24 hours of dex exposure. Dex also reduced the synthesis of both latent and mature forms of TGF-beta protein by approximately four-fold as determined by the mink lung epithelial cell growth inhibition bioassay. Assessment of the ratio of mature to latent protein found in conditioned medium of control compared to dex-treated cultures indicated that dexamethasone may reduce the activation of latent TGF-beta to mature biologically active TGF-beta. Dexamethasone inhibited the proliferation of MEPM cells despite the down-regulation of TGF-beta suggesting that dex-induced growth inhibition of MEPM cells is not mediated by TGF-beta. These data suggest that dex modulates TGF-beta signaling pathways directly by down-regulating TGF-beta expression and possibly indirectly by altering the availability of mature TGF-beta necessary to exert its biological effects in the developing palate.

UI MeSH Term Description Entries
D008648 Mesoderm The middle germ layer of an embryo derived from three paired mesenchymal aggregates along the neural tube. Mesenchyme,Dorsal Mesoderm,Intermediate Mesoderm,Lateral Plate Mesoderm,Mesenchyma,Paraxial Mesoderm,Dorsal Mesoderms,Intermediate Mesoderms,Lateral Plate Mesoderms,Mesenchymas,Mesoderm, Dorsal,Mesoderm, Intermediate,Mesoderm, Lateral Plate,Mesoderm, Paraxial,Mesoderms, Dorsal,Mesoderms, Intermediate,Mesoderms, Lateral Plate,Mesoderms, Paraxial,Paraxial Mesoderms,Plate Mesoderm, Lateral,Plate Mesoderms, Lateral
D008907 Mink Carnivores of genera Mustela and Neovison of the family MUSTELIDAE. The European mink has white upper and lower lips while the American mink lacks white upper lip. American Mink,European Mink,Mustela lutreola,Mustela macrodon,Mustela vison,Neovison vison,Sea Mink,Mink, American,Mink, European,Mink, Sea,Minks,Minks, Sea,Sea Minks,vison, Neovison
D010159 Palate The structure that forms the roof of the mouth. It consists of the anterior hard palate (PALATE, HARD) and the posterior soft palate (PALATE, SOFT). Incisive Papilla,Incisive Papillas,Palates,Papilla, Incisive,Papillas, Incisive
D002460 Cell Line Established cell cultures that have the potential to propagate indefinitely. Cell Lines,Line, Cell,Lines, Cell
D002478 Cells, Cultured Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others. Cultured Cells,Cell, Cultured,Cultured Cell
D003907 Dexamethasone An anti-inflammatory 9-fluoro-glucocorticoid. Hexadecadrol,Decaject,Decaject-L.A.,Decameth,Decaspray,Dexasone,Dexpak,Hexadrol,Maxidex,Methylfluorprednisolone,Millicorten,Oradexon,Decaject L.A.
D004622 Embryo, Mammalian The entity of a developing mammal (MAMMALS), generally from the cleavage of a ZYGOTE to the end of embryonic differentiation of basic structures. For the human embryo, this represents the first two months of intrauterine development preceding the stages of the FETUS. Embryonic Structures, Mammalian,Mammalian Embryo,Mammalian Embryo Structures,Mammalian Embryonic Structures,Embryo Structure, Mammalian,Embryo Structures, Mammalian,Embryonic Structure, Mammalian,Embryos, Mammalian,Mammalian Embryo Structure,Mammalian Embryonic Structure,Mammalian Embryos,Structure, Mammalian Embryo,Structure, Mammalian Embryonic,Structures, Mammalian Embryo,Structures, Mammalian Embryonic
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D012333 RNA, Messenger RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm. Messenger RNA,Messenger RNA, Polyadenylated,Poly(A) Tail,Poly(A)+ RNA,Poly(A)+ mRNA,RNA, Messenger, Polyadenylated,RNA, Polyadenylated,mRNA,mRNA, Non-Polyadenylated,mRNA, Polyadenylated,Non-Polyadenylated mRNA,Poly(A) RNA,Polyadenylated mRNA,Non Polyadenylated mRNA,Polyadenylated Messenger RNA,Polyadenylated RNA,RNA, Polyadenylated Messenger,mRNA, Non Polyadenylated
D013997 Time Factors Elements of limited time intervals, contributing to particular results or situations. Time Series,Factor, Time,Time Factor

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