Mouse smad8 phosphorylation downstream of BMP receptors ALK-2, ALK-3, and ALK-6 induces its association with Smad4 and transcriptional activity.
Smads are intracellular signaling mediators for TGF-beta superfamily. Smad1 and Smad5 are activated by BMP receptors. Here, we have cloned mouse Smad8 and functionally characterized its ability to transduce signals from BMP receptors. Constitutively active BMP type I receptors, ALK-3 and ALK-6, as well as ALK-2, were phosphorylated Smad8 and induced Smad8 interaction with Smad4. Nuclear translocation of Smad8 was stimulated by constitutively active BMP type I receptors. In contrast, constitutively active TGF-beta type I receptor, ALK-5, did not exhibit any action on Smad8. Smad8 and Smad4 cooperatively induced the promoter of Xvent2, a homeobox gene that responds specifically to BMP signaling. Dominant-negative Smad8 was shown to inhibit the increase of alkaline phosphatase activity induced by BMP-2 on pluripotent mesenchymal C3H10T1/2 and myoblastic C2C12 cell lines. The presence of Smad8 mRNA in mouse calvaria cells and osteoblasts suggests a role of Smad8 in the osteoblast differentiation and maturation.
Kawai
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S
Bone Diseases Group, Hoechst Marion Roussel, 102 Route de Noisy, Romainville Cedex, 93235, France. Shinji.Kawai.fr@hmrag.com
Faucheu
C
C
Gallea
S
S
Spinella-Jaegle
S
S
Atfi
A
A
Baron
R
R
Roman
S R
SR
D029404:Activin Receptors; D030201:Activin Receptors, Type I; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D055396:Bone Morphogenetic Protein 2; D052004:Bone Morphogenetic Protein Receptors; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D002454:Cell Differentiation; D002460:Cell Line; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009414:Nerve Growth Factors; D010006:Osteoblasts / Q000378:metabolism; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017978:Receptors, Growth Factor / Q000378:metabolism; D015398:Signal Transduction; D051785:Smad Proteins; D051901:Smad4 Protein; D051904:Smad8 Protein; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism*; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D029867:Xenopus Proteins
C525719:Bmp2 protein, mouse; C525720:Bmp2 protein, rat; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D009414:Nerve Growth Factors; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D017978:Receptors, Growth Factor; C107514:SMAD9 protein, human; D051785:Smad Proteins; D051901:Smad4 Protein; C490810:Smad4 protein, mouse; C490811:Smad4 protein, rat; D051904:Smad8 Protein; C491622:Smad8 protein, Xenopus; C491621:Smad9 protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D029867:Xenopus Proteins; C490808:smad4.1 protein, Xenopus; C117263:smad4.2 protein, Xenopus; C099992:ventx2.1 protein, Xenopus; D017346:Protein Serine-Threonine Kinases; D029404:Activin Receptors; D030201:Activin Receptors, Type I; D052004:Bone Morphogenetic Protein Receptors; D000469:Alkaline Phosphatase