Characterization of a Novel KRAB/C2H2Zinc Finger Transcription Factor Involved in Bone Development

Abstract

Osteogenic differentiation involves a cascade of coordinated gene expression that regulates cell proliferation and matrix protein formation in a defined temporo-spatial manner. Here we have used differential display to identify a novel zinc finger transcription factor (AJ18) that is induced during differentiation of bone cells in vitro and in vivo. The 64-kDa protein, encoded by a 7- kilobase mRNA, contains a Krüppel-associated box (KRAB) domain followed by 11 successive C2H2 zinc finger motifs. AJ18 mRNA, which is also expressed in kidney and brain, is developmentally regulated in embryonic tibiae and calvariae, with little expression in neonate and adult animals. During osteogenic differentiation in vitroAJ18 mRNA is expressed as cells approach confluence and declines as bone formation occurs. Using bacterially expressed, His-tagged AJ18 in a target detection assay, we identified a consensus binding sequence of 5′-CCACA-3′, which forms part of the consensus element forRunx2, a master gene for osteogenic differentiation. Overexpression of AJ18 suppressed Runx2-mediated transactivation of anosteocalcin promoter construct in transient transfection assays and reduced alkaline phosphatase activity in bone morphogenetic protein-induced C3H10T1/2 cells. These studies, therefore, have identified a novel zinc finger transcription factor in bone that can modulate Runx2 activity and osteogenic differentiation.AF321874 Osteogenic differentiation involves a cascade of coordinated gene expression that regulates cell proliferation and matrix protein formation in a defined temporo-spatial manner. Here we have used differential display to identify a novel zinc finger transcription factor (AJ18) that is induced during differentiation of bone cells in vitro and in vivo. The 64-kDa protein, encoded by a 7- kilobase mRNA, contains a Krüppel-associated box (KRAB) domain followed by 11 successive C2H2 zinc finger motifs. AJ18 mRNA, which is also expressed in kidney and brain, is developmentally regulated in embryonic tibiae and calvariae, with little expression in neonate and adult animals. During osteogenic differentiation in vitroAJ18 mRNA is expressed as cells approach confluence and declines as bone formation occurs. Using bacterially expressed, His-tagged AJ18 in a target detection assay, we identified a consensus binding sequence of 5′-CCACA-3′, which forms part of the consensus element forRunx2, a master gene for osteogenic differentiation. Overexpression of AJ18 suppressed Runx2-mediated transactivation of anosteocalcin promoter construct in transient transfection assays and reduced alkaline phosphatase activity in bone morphogenetic protein-induced C3H10T1/2 cells. These studies, therefore, have identified a novel zinc finger transcription factor in bone that can modulate Runx2 activity and osteogenic differentiation.AF321874 bone morphogenetic protein runt domain homeobox gene 2 core binding factor α osteogenic-specific factor transforming growth factor-β osteoblast-specificcis-acting element 2 fetal rat calvarial cell osteogenic protein-1 rat bone marrow cell polymerase chain reaction isopropyl-β-d-thiogalactoside polyacrylamide gel electrophoresis green fluorescent protein 4′,6′-diamidino-2-phenylindole Krüppel-associated box kilobase(s) base pair(s) double-stranded secreted protein acidic and rich in cysteine The characterization of bone morphogenetic proteins (BMPs1), their serine/threonine kinase membrane receptors, and downstream Smad effectors (reviewed in Refs. 1Heldin C.H. Miyazono K. ten Dijke P. Nature. 1997; 390: 465-471Crossref PubMed Scopus (3316) Google Scholar, 2Massague J. Annu. Rev. Biochem. 1998; 67: 753-791Crossref PubMed Scopus (3964) Google Scholar, 3Derynck R. Nature. 1998; 393: 737-739Crossref PubMed Scopus (28) Google Scholar) along with the identification ofRunx2/Cbfa-1/Osf2 (Runt domain factor 2/core binding factor α-1/osteoblast specific factor 2; reviewed in Ref. 4Karsenty G. Genes Dev. 1999; 13: 3037-3051Crossref PubMed Scopus (271) Google Scholar) as a master gene for osteogenesis (5Rodan G.A. Harada S. Cell. 1997; 89: 677-680Abstract Full Text Full Text PDF PubMed Scopus (116) Google Scholar) has established a template for osteogenic differentiation. However, the molecular mechanisms linking the osteogenic effects of BMPs and Runx2 and the expression of a bone matrix by osteoblastic cells are still largely unknown.BMPs were originally identified by their ability to induce ectopic bone formation (6Urist M.R. Science. 1965; 150: 893-899Crossref PubMed Scopus (4449) Google Scholar, 7Sampath T.K. Reddi A.H. Proc. Natl. Acad. Sci. U. S. A. 1981; 78: 7599-7603Crossref PubMed Scopus (468) Google Scholar). This unique bone-inductive activity indicates that BMPs provide the primordial signals for osteodifferentiation, as supported by the BMP-induced expression of Runx2. As a sub-group of the TGF-β superfamily, BMPs signal through type I and type II serine/threonine receptors on the cell surface (8ten Dijke P. Miyazono K. Heldin C.H. Curr. Opin. Cell Biol. 1996; 8: 139-145Crossref PubMed Scopus (236) Google Scholar). Upon ligand stimulation, the type I receptor phosphorylates a family of Smad proteins. Smad1, Smad5, and Smad8 mediate BMP signaling (9Hoodless P.A. Haerry T. Abdollah S. Stapleton M.O. Connor M.B. Attisano L. Wrana J.L. Cell. 1996; 85: 489-500Abstract Full Text Full Text PDF PubMed Scopus (623) Google Scholar, 10Nishimura R Kato Y. Chen D. Harris S.E. Mundy G.R. Yoneda T. J. Biol. Chem. 1998; 273: 1872-1879Abstract Full Text Full Text PDF PubMed Scopus (270) Google Scholar, 11Kawai S. Faucheu C. Gallea S. Spinella-Jaegle S. Atfi A. Baron R. Roman S.R. Biochem. Biophys. Res. Commun. 2000; 271: 682-687Crossref PubMed Scopus (46) Google Scholar) whereas Smad2 and Smad3 mediate TGF-β signaling (12Macias-Silva M. Abdollah S. Hoodless P.A. Pirone R. Attisano L. Wrana J.L. Cell. 1996; 87: 1215-1224Abstract Full Text Full Text PDF PubMed Scopus (651) Google Scholar, 13Zhang Y. Feng X. We R. Derynck R. Nature. 1996; 383: 168-172Crossref PubMed Scopus (757) Google Scholar). These receptor-regulated Smads form a complex with the common partner Smad (Smad4) and translocate to the nucleus, where they interact with other transcription factors, including Xenopus FAST1 and its mammalian homologues and also the c-Jun·c-Fos complex, to regulate the transcription of target genes. A murine isoform of Runx2 was first identified as a binding protein of an osteoblast-specific “AACCACA” enhancer element (OSE2) of the osteocalcingene (14Ducy P. Starbuck M. Priemel M. Shen J. Pinero G. Geoffroy V. Amling M. Karsenty G. Genes Dev. 1999; 13: 1025-1036Crossref PubMed Scopus (703) Google Scholar). Runx2-dependent gene expression increases in parallel with osteogenic differentiation (14Ducy P. Starbuck M. Priemel M. Shen J. Pinero G. Geoffroy V. Amling M. Karsenty G. Genes Dev. 1999; 13: 1025-1036Crossref PubMed Scopus (703) Google Scholar, 15Ji C. Casinghino S. Chang D.J. Chen Y. Javed A. Ito Y. Hiebert S.W. Lian J.B. Stein G.S. McCarthy T.L. Centrella M. J. Cell. Biochem. 1998; 69: 353-363Crossref PubMed Scopus (87) Google Scholar), and loss ofRunx2 by homozygous gene deletion in mice arrests skeletal tissue development (16Komori T. Yagi H. Nomura S. Yamaguchi A. Sasaki K. Deguchi K. Shimizu Y. Bronson R.T. Gao Y.H. Inada M. Sato M. Okamoto R. Kitamura Y. Yoshiki S. Kishimoto T. Cell. 1997; 89: 755-764Abstract Full Text Full Text PDF PubMed Scopus (3597) Google Scholar, 17Otto F. Thornell A.P. Crompton T. Denzel A. Gilmour K.C. Rosewell I.R. Stamp G.W. Beddington R.S. Mundlos S. Olsen B.R. Selby P.B. Owen M.J. Cell. 1997; 89: 765-771Abstract Full Text Full Text PDF PubMed Scopus (2377) Google Scholar). Moreover, Runx and Smads have been shown to functionally interact and stimulate transcription of the germline Ig Cα promoter for which binding of both factors to their specific binding sites is essential (18Hanai J. Chen L.F. Kanno T. Ohtani-Fujita N. Kim W.Y. Guo W.H. Imamura T. Ishidou Y. Fukuchi M. Shi M.J. J. M. Miyazono K. Ito Y. J. Biol. Chem. 1999; Full Text Full Text PDF PubMed Scopus Google Scholar). the complex regulates in the differentiation of target for complex have to in osteoblastic we used differential display to identify expressed by fetal rat calvarial cells that were by an we identified a novel AJ18 A. S. J. M. A. C. and of of the of Scholar). Here we the characterization of AJ18 as a zinc finger transcription factor that is during osteoblastic differentiation and that to modulate osteogenic differentiation through effects on Runx2 of the zinc finger protein family have been A. A. 8: PubMed Scopus Google Scholar, Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar), little is of their Moreover, target target have been identified for proteins C. M. L. Cell Biol. 1999; PubMed Scopus Google Scholar). we have and a novel zinc finger transcription that is developmentally expressed in bone and that to regulate osteoblastic differentiation. AJ18 contains 11 C2H2 zinc finger and an Krüppel-associated box domain which is to as a of We that the zinc finger of the is in and for binding of AJ18 to a including the for Runx2. that AJ18 can the osteogenic effects of a transcription factor that is for bone development (5Rodan G.A. Harada S. Cell. 1997; 89: 677-680Abstract Full Text Full Text PDF PubMed Scopus (116) Google Scholar), and alkaline phosphatase activity in C3H10T1/2 cells. is the first to identify a protein that is in osteoblastic C2H2 zinc finger proteins a family of that is to the of zinc finger the protein sequence T. Biol. PubMed Scopus Google Scholar). are zinc finger that for proteins as with zinc finger motifs. The proteins in the have been identified as in cell proliferation and differentiation. The proteins expressed by the of zinc finger have zinc finger and are which to both the gene and to F. U. H. T. Cell. Full Text PDF PubMed Scopus Google Scholar) and which regulates the gene M. D. D. R. Google Scholar), the of the proteins expressed by is largely of C2H2 zinc finger proteins a which is in proteins and to have with as a H. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). can on sequence C. M. L. Cell Biol. 1999; PubMed Scopus Google a A box both A and an A box with a on and sequence AJ18 to a of the of a A and the A domain is for whereas the domain has a H. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar, G. V. A. L. Res. PubMed Scopus Google Scholar, A. D. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). The domain with J. P. R. J. Biochem. Biol. 1998; PubMed Scopus Google Scholar, P. Res. 1996; PubMed Scopus Google Scholar, Genes Dev. 1996; PubMed Scopus Google Scholar), which as a for transcription factors in and transcription P. M. Biol. Chem. 1997; PubMed Scopus Google Scholar). However, target target have been identified for transcription of has identified a novel zinc finger protein, with a domain and zinc that a sequence in the growth gene with which is as a in the of in cell growth and differentiation L. P. S. A. Chen W.H. Cell. 2000; Full Text Full Text PDF PubMed Scopus Google with zinc finger proteins as transcription factors, we have an protein and that AJ18 is to the and that a consensus binding that a sequence Moreover, of the expression of a form of AJ18 the domain that the is for for We that the binding sequence for AJ18 is the consensus binding sequence for Runx2 which is in the of including and that are in bone formation P. R. Geoffroy V. Karsenty G. Cell. 1997; 89: Full Text Full Text PDF PubMed Scopus Google Scholar). that the of the target detection assay, to AJ18 in the of we were to for that of the protein by the target detection assay, for a sequence is to has been shown to interact with the matrix M. M. J. Biol. Chem. 1996; 271: Full Text Full Text PDF PubMed Scopus Google Scholar). in AJ18 activity induced by Runx2 in a gene in a This by the domain as of the AJ18 and for binding which the also suppressed transcription of a the of to AJ18 and Runx2 for the of the transfection of the cells used in transient transfection we have been to AJ18 the expression of we are of a rat bone marrow cell that osteogenic differentiation in AJ18 modulate Runx2-mediated osteogenic differentiation is by the of alkaline phosphatase expression in cells with an AJ18 expression an target of alkaline phosphatase is an of osteogenic differentiation that is for Javed A. Kim S. V. Stein J.L. Stein G.S. Lian J.B. J. Cell. Biochem. 1999; PubMed Scopus Google Scholar). of the expression of AJ18 and Runx2 during bone formation in and in vitro is also with an of transcription factors the of expression of the proteins the cell is AJ18 and Runx2 are and are expressed as osteoblastic differentiation the mRNA expression of both proteins as bone tissue formation is However, the expression of AJ18 in other embryonic including kidney and brain, indicates a for AJ18 in we have a novel zinc finger transcription expressed in bone which has the to modulate the of Runx2. The characterization of bone morphogenetic proteins (BMPs1), their serine/threonine kinase membrane receptors, and downstream Smad effectors (reviewed in Refs. 1Heldin C.H. Miyazono K. ten Dijke P. Nature. 1997; 390: 465-471Crossref PubMed Scopus (3316) Google Scholar, 2Massague J. Annu. Rev. Biochem. 1998; 67: 753-791Crossref PubMed Scopus (3964) Google Scholar, 3Derynck R. Nature. 1998; 393: 737-739Crossref PubMed Scopus (28) Google Scholar) along with the identification ofRunx2/Cbfa-1/Osf2 (Runt domain factor 2/core binding factor α-1/osteoblast specific factor 2; reviewed in Ref. 4Karsenty G. Genes Dev. 1999; 13: 3037-3051Crossref PubMed Scopus (271) Google Scholar) as a master gene for osteogenesis (5Rodan G.A. Harada S. Cell. 1997; 89: 677-680Abstract Full Text Full Text PDF PubMed Scopus (116) Google Scholar) has established a template for osteogenic differentiation. However, the molecular mechanisms linking the osteogenic effects of BMPs and Runx2 and the expression of a bone matrix by osteoblastic cells are still largely BMPs were originally identified by their ability to induce ectopic bone formation (6Urist M.R. Science. 1965; 150: 893-899Crossref PubMed Scopus (4449) Google Scholar, 7Sampath T.K. Reddi A.H. Proc. Natl. Acad. Sci. U. S. A. 1981; 78: 7599-7603Crossref PubMed Scopus (468) Google Scholar). This unique bone-inductive activity indicates that BMPs provide the primordial signals for osteodifferentiation, as supported by the BMP-induced expression of Runx2. As a sub-group of the TGF-β superfamily, BMPs signal through type I and type II serine/threonine receptors on the cell surface (8ten Dijke P. Miyazono K. Heldin C.H. Curr. Opin. Cell Biol. 1996; 8: 139-145Crossref PubMed Scopus (236) Google Scholar). Upon ligand stimulation, the type I receptor phosphorylates a family of Smad proteins. Smad1, Smad5, and Smad8 mediate BMP signaling (9Hoodless P.A. Haerry T. Abdollah S. Stapleton M.O. Connor M.B. Attisano L. Wrana J.L. Cell. 1996; 85: 489-500Abstract Full Text Full Text PDF PubMed Scopus (623) Google Scholar, 10Nishimura R Kato Y. Chen D. Harris S.E. Mundy G.R. Yoneda T. J. Biol. Chem. 1998; 273: 1872-1879Abstract Full Text Full Text PDF PubMed Scopus (270) Google Scholar, 11Kawai S. Faucheu C. Gallea S. Spinella-Jaegle S. Atfi A. Baron R. Roman S.R. Biochem. Biophys. Res. Commun. 2000; 271: 682-687Crossref PubMed Scopus (46) Google Scholar) whereas Smad2 and Smad3 mediate TGF-β signaling (12Macias-Silva M. Abdollah S. Hoodless P.A. Pirone R. Attisano L. Wrana J.L. Cell. 1996; 87: 1215-1224Abstract Full Text Full Text PDF PubMed Scopus (651) Google Scholar, 13Zhang Y. Feng X. We R. Derynck R. Nature. 1996; 383: 168-172Crossref PubMed Scopus (757) Google Scholar). These receptor-regulated Smads form a complex with the common partner Smad (Smad4) and translocate to the nucleus, where they interact with other transcription factors, including Xenopus FAST1 and its mammalian homologues and also the c-Jun·c-Fos complex, to regulate the transcription of target genes. A murine isoform of Runx2 was first identified as a binding protein of an osteoblast-specific “AACCACA” enhancer element (OSE2) of the osteocalcingene (14Ducy P. Starbuck M. Priemel M. Shen J. Pinero G. Geoffroy V. Amling M. Karsenty G. Genes Dev. 1999; 13: 1025-1036Crossref PubMed Scopus (703) Google Scholar). Runx2-dependent gene expression increases in parallel with osteogenic differentiation (14Ducy P. Starbuck M. Priemel M. Shen J. Pinero G. Geoffroy V. Amling M. Karsenty G. Genes Dev. 1999; 13: 1025-1036Crossref PubMed Scopus (703) Google Scholar, 15Ji C. Casinghino S. Chang D.J. Chen Y. Javed A. Ito Y. Hiebert S.W. Lian J.B. Stein G.S. McCarthy T.L. Centrella M. J. Cell. Biochem. 1998; 69: 353-363Crossref PubMed Scopus (87) Google Scholar), and loss ofRunx2 by homozygous gene deletion in mice arrests skeletal tissue development (16Komori T. Yagi H. Nomura S. Yamaguchi A. Sasaki K. Deguchi K. Shimizu Y. Bronson R.T. Gao Y.H. Inada M. Sato M. Okamoto R. Kitamura Y. Yoshiki S. Kishimoto T. Cell. 1997; 89: 755-764Abstract Full Text Full Text PDF PubMed Scopus (3597) Google Scholar, 17Otto F. Thornell A.P. Crompton T. Denzel A. Gilmour K.C. Rosewell I.R. Stamp G.W. Beddington R.S. Mundlos S. Olsen B.R. Selby P.B. Owen M.J. Cell. 1997; 89: 765-771Abstract Full Text Full Text PDF PubMed Scopus (2377) Google Scholar). Moreover, Runx and Smads have been shown to functionally interact and stimulate transcription of the germline Ig Cα promoter for which binding of both factors to their specific binding sites is essential (18Hanai J. Chen L.F. Kanno T. Ohtani-Fujita N. Kim W.Y. Guo W.H. Imamura T. Ishidou Y. Fukuchi M. Shi M.J. J. M. Miyazono K. Ito Y. J. Biol. Chem. 1999; Full Text Full Text PDF PubMed Scopus Google Scholar). the complex regulates in the differentiation of target for complex have to in osteoblastic we used differential display to identify expressed by fetal rat calvarial cells that were by an we identified a novel AJ18 A. S. J. M. A. C. and of of the of Scholar). Here we the characterization of AJ18 as a zinc finger transcription factor that is during osteoblastic differentiation and that to modulate osteogenic differentiation through effects on Runx2 of the zinc finger protein family have been A. A. 8: PubMed Scopus Google Scholar, Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar), little is of their Moreover, target target have been identified for proteins C. M. L. Cell Biol. 1999; PubMed Scopus Google Scholar). we have and a novel zinc finger transcription that is developmentally expressed in bone and that to regulate osteoblastic differentiation. AJ18 contains 11 C2H2 zinc finger and an Krüppel-associated box domain which is to as a of We that the zinc finger of the is in and for binding of AJ18 to a including the for Runx2. that AJ18 can the osteogenic effects of a transcription factor that is for bone development (5Rodan G.A. Harada S. Cell. 1997; 89: 677-680Abstract Full Text Full Text PDF PubMed Scopus (116) Google Scholar), and alkaline phosphatase activity in C3H10T1/2 cells. is the first to identify a protein that is in osteoblastic C2H2 zinc finger proteins a family of that is to the of zinc finger the protein sequence T. Biol. PubMed Scopus Google Scholar). are zinc finger that for proteins as with zinc finger motifs. The proteins in the have been identified as in cell proliferation and differentiation. The proteins expressed by the of zinc finger have zinc finger and are which to both the gene and to F. U. H. T. Cell. Full Text PDF PubMed Scopus Google Scholar) and which regulates the gene M. D. D. R. Google Scholar), the of the proteins expressed by is largely of C2H2 zinc finger proteins a which is in proteins and to have with as a H. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). can on sequence C. M. L. Cell Biol. 1999; PubMed Scopus Google a A box both A and an A box with a on and sequence AJ18 to a of the of a A and the A domain is for whereas the domain has a H. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar, G. V. A. L. Res. PubMed Scopus Google Scholar, A. D. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). The domain with J. P. R. J. Biochem. Biol. 1998; PubMed Scopus Google Scholar, P. Res. 1996; PubMed Scopus Google Scholar, Genes Dev. 1996; PubMed Scopus Google Scholar), which as a for transcription factors in and transcription P. M. Biol. Chem. 1997; PubMed Scopus Google Scholar). However, target target have been identified for transcription of has identified a novel zinc finger protein, with a domain and zinc that a sequence in the growth gene with which is as a in the of in cell growth and differentiation L. P. S. A. Chen W.H. Cell. 2000; Full Text Full Text PDF PubMed Scopus Google with zinc finger proteins as transcription factors, we have an protein and that AJ18 is to the and that a consensus binding that a sequence Moreover, of the expression of a form of AJ18 the domain that the is for for We that the binding sequence for AJ18 is the consensus binding sequence for Runx2 which is in the of including and that are in bone formation P. R. Geoffroy V. Karsenty G. Cell. 1997; 89: Full Text Full Text PDF PubMed Scopus Google Scholar). that the of the target detection assay, to AJ18 in the of we were to for that of the protein by the target detection assay, for a sequence is to has been shown to interact with the matrix M. M. J. Biol. Chem. 1996; 271: Full Text Full Text PDF PubMed Scopus Google Scholar). in AJ18 activity induced by Runx2 in a gene in a This by the domain as of the AJ18 and for binding which the also suppressed transcription of a the of to AJ18 and Runx2 for the of the transfection of the cells used in transient transfection we have been to AJ18 the expression of we are of a rat bone marrow cell that osteogenic differentiation in AJ18 modulate Runx2-mediated osteogenic differentiation is by the of alkaline phosphatase expression in cells with an AJ18 expression an target of alkaline phosphatase is an of osteogenic differentiation that is for Javed A. Kim S. V. Stein J.L. Stein G.S. Lian J.B. J. Cell. Biochem. 1999; PubMed Scopus Google Scholar). of the expression of AJ18 and Runx2 during bone formation in and in vitro is also with an of transcription factors the of expression of the proteins the cell is AJ18 and Runx2 are and are expressed as osteoblastic differentiation the mRNA expression of both proteins as bone tissue formation is However, the expression of AJ18 in other embryonic including kidney and brain, indicates a for AJ18 in we have a novel zinc finger transcription expressed in bone which has the to modulate the of Runx2. of the zinc finger protein family have been A. A. 8: PubMed Scopus Google Scholar, Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar), little is of their Moreover, target target have been identified for proteins C. M. L. Cell Biol. 1999; PubMed Scopus Google Scholar). we have and a novel zinc finger transcription that is developmentally expressed in bone and that to regulate osteoblastic differentiation. AJ18 contains 11 C2H2 zinc finger and an Krüppel-associated box domain which is to as a of We that the zinc finger of the is in and for binding of AJ18 to a including the for Runx2. that AJ18 can the osteogenic effects of a transcription factor that is for bone development (5Rodan G.A. Harada S. Cell. 1997; 89: 677-680Abstract Full Text Full Text PDF PubMed Scopus (116) Google Scholar), and alkaline phosphatase activity in C3H10T1/2 cells. is the first to identify a protein that is in osteoblastic differentiation. The C2H2 zinc finger proteins a family of that is to the of zinc finger the protein sequence T. Biol. PubMed Scopus Google Scholar). are zinc finger that for proteins as with zinc finger motifs. The proteins in the have been identified as in cell proliferation and differentiation. The proteins expressed by the of zinc finger have zinc finger and are which to both the gene and to F. U. H. T. Cell. Full Text PDF PubMed Scopus Google Scholar) and which regulates the gene M. D. D. R. Google Scholar), the of the proteins expressed by is largely of C2H2 zinc finger proteins a which is in proteins and to have with as a H. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). can on sequence C. M. L. Cell Biol. 1999; PubMed Scopus Google a A box both A and an A box with a on and sequence AJ18 to a of the of a A and the A domain is for whereas the domain has a H. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar, G. V. A. L. Res. PubMed Scopus Google Scholar, A. D. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). The domain with J. P. R. J. Biochem. Biol. 1998; PubMed Scopus Google Scholar, P. Res. 1996; PubMed Scopus Google Scholar, Genes Dev. 1996; PubMed Scopus Google Scholar), which as a for transcription factors in and transcription P. M. Biol. Chem. 1997; PubMed Scopus Google Scholar). However, target target have been identified for transcription of has identified a novel zinc finger protein, with a domain and zinc that a sequence in the growth gene with which is as a in the of in cell growth and differentiation L. P. S. A. Chen W.H. Cell. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar). with zinc finger proteins as transcription factors, we have an protein and that AJ18 is to the and that a consensus binding that a sequence Moreover, of the expression of a form of AJ18 the domain that the is for for We that the binding sequence for AJ18 is the consensus binding sequence for Runx2 which is in the of including and that are in bone formation P. R. Geoffroy V. Karsenty G. Cell. 1997; 89: Full Text Full Text PDF PubMed Scopus Google Scholar). that the of the target detection assay, to AJ18 in the of we were to for that of the protein by the target detection assay, for a sequence is to has been shown to interact with the matrix M. M. J. Biol. Chem. 1996; 271: Full Text Full Text PDF PubMed Scopus Google Scholar). in AJ18 activity induced by Runx2 in a gene in a This by the domain as of the AJ18 and for binding which the also suppressed transcription of a the of to AJ18 and Runx2 for the of the transfection of the cells used in transient transfection we have been to AJ18 the expression of we are of a rat bone marrow cell that osteogenic differentiation in AJ18 modulate Runx2-mediated osteogenic differentiation is by the of alkaline phosphatase expression in cells with an AJ18 expression an target of alkaline phosphatase is an of osteogenic differentiation that is for Javed A. Kim S. V. Stein J.L. Stein G.S. Lian J.B. J. Cell. Biochem. 1999; PubMed Scopus Google Scholar). of the expression of AJ18 and Runx2 during bone formation in and in vitro is also with an of transcription factors the of expression of the proteins the cell is AJ18 and Runx2 are and are expressed as osteoblastic differentiation the mRNA expression of both proteins as bone tissue formation is However, the expression of AJ18 in other embryonic including kidney and brain, indicates a for AJ18 in we have a novel zinc finger transcription expressed in bone which has the to modulate the of Runx2. We are to for the and to Karsenty of for the and the We also and Chen for their