TIEG1 null mouse-derived osteoblasts are defective in mineralization and in support of osteoclast differentiation in vitro.
Transforming growth factor beta-inducible early gene 1 (TIEG1) is a member of the Kruppel-like transcription factor family. To understand the physiological role of TIEG1, we generated TIEG(-/-) (null) mice and found that the TIEG(-/-) mice had increased osteoblast numbers with no increased bone formation parameters. However, when calvarial osteoblasts (OBs) were isolated from neonatal TIEG(-/-) and TIEG(+/+) mice and cultured in vitro, the TIEG(-/-) cells displayed reduced expression of important OB differentiation markers. When the OBs were differentiated in vitro by treatment with bone morphogenic protein 2, the OBs from TIEG(+/+) calvaria displayed several mineralized nodules in culture, whereas those from TIEG(-/-) mice showed no nodules. To characterize the OBs' ability to support osteoclast differentiation, the OBs from TIEG(+/+) and TIEG(-/-) mice were cultured with marrow and spleen cells from TIEG(+/+) mice. Significantly fewer osteoclasts developed when TIEG(-/-) OBs were used to support osteoclast differentiation than when TIEG(+/+) OBs were used. Examination of gene expression in the TIEG(-/-) OBs revealed decreased RANKL and increased OPG expression compared to TIEG(+/+) OBs. The addition of RANKL to these cocultures only partially restored the ability of TIEG(-/-) OBs to support osteoclast differentiation, whereas M-CSF alone or combined with RANKL had no additional effect on osteoclast differentiation. We conclude from these data that TIEG1 expression in OBs is critical for both osteoblast-mediated mineralization and osteoblast support of osteoclast differentiation.
Subramaniam
Malayannan
M
Department of Biochemistry and Molecular Biology, 1601B Guggenheim Bldg., Mayo Clinic College of Medicine, 200 First Street S.W., Rochester, MN 55905, USA. subramaniam.malayannan@mayo.edu
Gorny
Genevieve
G
Johnsen
Steven A
SA
Monroe
David G
DG
Evans
Glenda L
GL
Fraser
Daniel G
DG
Rickard
David J
DJ
Rasmussen
Kay
K
van Deursen
Jan M A
JM
Turner
Russell T
RT
Oursler
Merry Jo
MJ
Spelsberg
Thomas C
TC
D000818:Animals; D001853:Bone Marrow / Q000378:metabolism; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D002113:Calcification, Physiologic / Q000502:physiology; D002352:Carrier Proteins / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology*; D049109:Cell Proliferation; D018920:Coculture Techniques; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism; D010010:Osteoclasts / Q000166:cytology* / Q000378:metabolism; D053244:Osteoprotegerin; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor; D013154:Spleen / Q000166:cytology / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D051741:Kruppel-Like Transcription Factors; D051765:Early Growth Response Transcription Factors
D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D053244:Osteoprotegerin; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; C525719:Bmp2 protein, mouse; C505687:Tnfrsf11a protein, mouse; C506031:Tnfrsf11b protein, mouse; C505689:Tnfsf11 protein, mouse; C569958:KLF10 protein, mouse; D051741:Kruppel-Like Transcription Factors; D051765:Early Growth Response Transcription Factors