NF-kappaB specifically activates BMP-2 gene expression in growth plate chondrocytes in vivo and in a chondrocyte cell line in vitro.
Bone morphogenetic protein-2 (BMP-2) regulates growth plate chondrogenesis during development and postnatal bone growth, but the control mechanisms of BMP-2 expression in growth plate chondrocytes are unknown. Here we have used both in vitro and in vivo approaches to demonstrate that transcription factor, NF-kappaB, regulates BMP-2 gene expression in chondrocytes. Two putative NF-kappaB response elements were found in the -2712/+165 region of the BMP-2 gene. Cotransfection of mutant I-kappaBalpha expression plasmids with BMP-2 promoter-luciferase reporters into TMC-23 chondrocyte cell line suppressed BMP-2 transcription. Mutations in NF-kappaB response elements in the BMP-2 gene lead to decreases in BMP-2 promoter activity. Electrophoretic mobility shift assay using nuclear extracts from TMC-23 chondrocytic cells revealed that the NF-kappaB subunits p50 and p65 bound to the NF-kappaB response elements of the BMP-2 gene. Thus, NF-kappaB may positively regulate BMP-2 gene transcription. Consistent with these findings, expression of BMP-2 mRNA was significantly reduced in growth plate chondrocytes in NF-kappaB p50/p52 dKO mice, which associated with decreased numbers of 5-bromo-2'-deoxyuridine (BrdUrd)-positive cells in the proliferating zone of growth plate in these mice. Therefore, in postnatal growth plate chondrocytes, expression of BMP-2 is regulated by NF-kappaB, which may play an important role in chondrogenesis.
Feng
Jian Q
JQ
Department of Oral Biology, School of Dentistry, University of Missouri, Kansas City, Missouri 64108, USA.
Xing
Lianping
L
Zhang
Jiang-Hong
JH
Zhao
Ming
M
Horn
Diane
D
Chan
Jeannie
J
Boyce
Brendan F
BF
Harris
Stephen E
SE
Mundy
Gregory R
GR
Chen
Di
D
D000818:Animals; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000235:genetics*; D002460:Cell Line; D019902:Chondrocytes / Q000737:chemistry*; D024202:Electrophoretic Mobility Shift Assay; D015870:Gene Expression / Q000187:drug effects*; D006132:Growth Plate / Q000737:chemistry*; D020672:I-kappa B Proteins / Q000235:genetics; D017403:In Situ Hybridization; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D016297:Mutagenesis, Site-Directed; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000172:deficiency / Q000235:genetics / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000032:analysis; D020218:Response Elements; D016212:Transforming Growth Factor beta; D001616:beta-Galactosidase / Q000032:analysis / Q000235:genetics
C525719:Bmp2 protein, mouse; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606205:Nfkbia protein, mouse; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D000072000:NF-KappaB Inhibitor alpha; D001616:beta-Galactosidase