PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Core Binding Factor alpha Subunits”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources
PubMed2001

IL-1 induces collagenase-3 (MMP-13) promoter activity in stably transfected chondrocytic cells: requirement for Runx-2 and activation by p38 MAPK and JNK pathways.

Osteoarthritic chondrocytes secrete matrix metalloproteinase-13 (MMP-13) in response to interleukin-1 (IL-1), causing digestion of type II collagen in cartilage. Using chondrocytic cells, we previously determined that IL-1 induced a strong MMP-13 transcriptional response that requires p38 MAPK, JNK and the transcription factor NF-kappaB. Now, we have studied the tissue-specific transcriptional regulation of MMP-13. Constitutive expression of the transcription factor Runx-2 correlated with the ability of a cell type to express MMP-13 and was required for IL-1 induction; moreover, Runx-2 enhanced IL-1 induction of MMP-13 transcription by synergizing with the p38 MAPK signaling pathway. Transiently transfected MMP-13 promoters were not IL-1 inducible. However, -405 bp of stably integrated promoter was sufficient for 5- to 6-fold IL-1 induction of reporter activity and this integrated reporter required the same p38 MAPK pathway as the endogenous gene. Finally, mutation of the proximal Runx binding site and the proximal AP-1 site blunted the transcriptional response to IL-1, and double mutation synergistically decreased reporter activity. In summary, our data suggest that the transcriptional MMP-13 response to IL-1 is controlled by the p38 pathway interacting at the MMP-13 promoter through the tissue-specific transcription factor Runx-2 and the ubiquitous AP-1 transcription factor.

Animals↗
PubMed2001

Crystallization and preliminary X-ray analyses of quaternary, ternary and binary protein-DNA complexes with involvement of AML1/Runx-1/CBFalpha Runt domain, CBFbeta and the C/EBPbeta bZip region.

Three types of protein-DNA complexes, AML1/Runx-1/CBFalpha(Runt)-CBFbeta-C/EBPbeta(bZip)-DNA (CBFalpha-beta-C/EBPbeta-DNA), AML1/Runx-1/CBFalpha(Runt)-C/EBPbeta(bZip)-DNA (CBFalpha-C/EBPbeta-DNA) and AML1/Runx-1/CBFalpha(Runt)-DNA (CBFalpha-DNA), were crystallized. The crystals were all orthorhombic and belonged to space groups C222(1), P2(1)2(1)2 and P2(1)2(1)2(1), respectively. The resolutions of CBFalpha-beta-C/EBPbeta-DNA and CBFalpha-C/EBPbeta-DNA crystals were both 3 A, while that of the CBFalpha-DNA crystal was 2.65 A. Complete data sets were collected for all of the native crystals, along with MAD and MIR data sets for CBFalpha-beta-C/EBPbeta-DNA. The heavy-atom site was determined using MAD data for a gold derivative of CBFalpha-beta-C/EBPbeta-DNA.

Animals↗
PubMed2001

runt homology domain transcription factors (Runx, Cbfa, and AML) mediate repression of the bone sialoprotein promoter: evidence for promoter context-dependent activity of Cbfa proteins.

Expression of the bone sialoprotein (BSP) gene, a marker of bone formation, is largely restricted to cells in mineralized tissues. Recent studies have shown that the Cbfa1 (also known as Runx2, AML-3, and PEBP2alphaA) transcription factor supports commitment and differentiation of progenitor cells to hypertrophic chondrocytes and osteoblasts. This study addresses the functional involvement of Cbfa sites in expression of the Gallus BSP gene. Gel mobility shift analyses with nuclear extracts from ROS 17/2.8 osteoblastic cells revealed that multiple Cbfa consensus sequences are functional Cbfa DNA binding sites. Responsiveness of the 1.2-kb Gallus BSP promoter to Cbfa factors Cbfa1, Cbfa2, and Cbfa3 was assayed in osseous and nonosseous cells. Each of the Cbfa factors mediated repression of the wild-type BSP promoter, in contrast to their well known activation of various hematopoietic and skeletal phenotypic genes. Suppression of BSP by Cbfa factors was not observed in BSP promoters in which Cbfa sites were deleted or mutated. Expression of the endogenous BSP gene in Gallus osteoblasts was similarly downregulated by forced expression of Cbfa factors. Our data indicate that Cbfa repression of the BSP promoter does not involve the transducin-like enhancer (TLE) proteins. Neither coexpression of TLE1 or TLE2 nor the absence of the TLE interaction motif of Cbfa1 (amino acids 501 to 513) influenced repressor activity. However, removal of the C terminus of Cbfa1 (amino acids 362 to 513) relieved suppression of the BSP promoter. Our results, together with the evolutionary conservation of the seven Cbfa sites in the Gallus and human BSP promoters, suggest that suppressor activity by Cbfa is of significant physiologic consequence and may contribute to spatiotemporal expression of BSP during bone development.

Animals↗
PubMed2005

Oct-1 counteracts autoinhibition of Runx2 DNA binding to form a novel Runx2/Oct-1 complex on the promoter of the mammary gland-specific gene beta-casein.

The transcription factor Runx2 is essential for the expression of a number of bone-specific genes and is primarily considered a master regulator of bone development. Runx2 is also expressed in mammary epithelial cells, but its role in the mammary gland has not been established. Here we show that Runx2 forms a novel complex with the ubiquitous transcription factor Oct-1 to regulate the expression of the mammary gland-specific gene beta-casein. The Runx2/Oct-1 complex forms on a Runx/octamer element which is highly conserved in casein promoters. Chromatin immunoprecipitation, RNA interference, promoter mutagenesis, and transient expression analyses were used to demonstrate that the Runx2/Oct-1 complex contributes to the transcriptional regulation of the beta-casein gene. Analysis of the complex revealed autoinhibitory domains for DNA binding in both the N-terminal and the C-terminal regions of Runx2. Oct-1 stimulates the recruitment of Runx2 to the beta-casein promoter by interacting with the C-terminal region of Runx2, suggesting that Oct-1 stimulates Runx2 recruitment by relieving the autoinhibition of Runx2 DNA binding. These findings demonstrate that Runx2 collaborates with Oct-1 and contributes to the expression of a mammary gland-specific gene.

Animals↗
PubMed2003

Impaired osteoblastic differentiation, reduced bone formation, and severe osteoporosis in noggin-overexpressing mice.

We describe the effects of the overexpression of noggin, a bone morphogenetic protein (BMP) inhibitor, on osteoblast differentiation and bone formation. Cells of the osteoblast and chondrocyte lineages, as well as bone marrow macrophages, showed intense beta-gal histo- or cytostaining in adult noggin+/- mice that had a LacZ transgene inserted at the site of noggin deletion. Despite identical BMP levels, however, osteoblasts of 20-month-old C57BL/6J and 4-month-old senescence-accelerated mice (SAM-P6 mice) had noggin expression levels that were approximately fourfold higher than those of 4-month-old C57BL/6J and SAM-R1 (control) mice, respectively. U-33 preosteoblastic cells overexpressing the noggin gene showed defective maturation and, in parallel, a decreased expression of Runx-2, bone sialoprotein, osteocalcin, and RANK-L. Noggin did not inhibit the ligandless signaling and pro-differentiation action of the constitutively activated BMP receptor type 1A, ca-ALK-3. Transgenic mice overexpressing noggin in mature osteocalcin-positive osteoblasts showed dramatic decreases in bone mineral density and bone formation rates with histological evidence of decreased trabecular bone and CFU-osteoblast colonies at 4 and 8 months. Together, the results provide compelling evidence that noggin, expressed in mature osteoblasts, inhibits osteoblast differentiation and bone formation. Thus, the overproduction of noggin during biological aging may result in impaired osteoblast formation and function and hence, net bone loss.

Aging↗
PubMed2001

Control and counter-control of TGF-beta activity through FAST and Runx (CBFa) transcriptional elements in osteoblasts.

FAST and Runx (CBFa) transcription factors, which are expressed during specific phases of embryogenesis and tissue patterning, bind directly to Smad proteins and integrate effects induced by various TGF-beta gene family members. The DNA binding sequences for FAST and Runx differ only minimally. The isoform Runx2 (previously termed CBFa1) is highly expressed by osteoblasts and regulates expression of the TGF-beta receptor I in these cells. Here we show that FAST-dependent transcription is endogenously restricted in osteoblasts but can be significantly enhanced by disruption of Runx2 expression. Native and synthetic Runx2 bind to both Runx and FAST binding sequences, whereas FAST-1 efficiently binds only to the FAST binding sequence. However, overexpression of FAST-1 potently suppresses TGF-beta receptor I gene expression in osteoblasts and thereby reduces TGF-beta activity independently of competing for Runx2 at the level of DNA binding. These results provide a new example of how nuclear factors associated with specific developmental states or tissue lineages may influence TGF-beta-dependent events in restricted ways.

Activin Receptors, Type I↗
PubMed2003

Runx2/Cbfa1: a multifunctional regulator of bone formation.

Runx2/Cbfa/AML3 is a member of the runt homology domain family of transcription factors, essential for osteoblast differentiation and bone formation. Defining the molecular mechanisms by which Runx2 can function as a master regulatory gene for activating the program of osteoblastogenesis has provided novel insights for transcriptional regulation of tissue-specific genes. Regulation of Runx expression has the potential to serve as a basis for the design of novel therapeutic strategies for promoting bone formation. Here we review the unique properties of Runx2 that mediate several key functions necessary for regulating skeletogenesis, controlling osteoblast growth and differentiation, and integrating the complex pathways required for bone formation and turnover.

Animals↗
PubMed2005

Dominant negative effects of the AML1/ETO fusion oncoprotein.

The t(8;21)(q22;q22) translocation, present in 10-15% of acute myeloid leukemia (AML) cases results in the production of the AML1/ETO fusion protein. Expression of AML1/ETO in patients or mouse models is not sufficient to induce AML. Despite convincing evidence that AML1/ETO is directly involved in the pathogenesis of AML, the underlying mechanism is not well understood. Genetic and biochemical experiments suggest that AML1/ETO is a dominant inhibitor of the core binding factor (CBF) transcription complex that includes AML1 (RUNX1), the N-terminal fusion partner in the t(8;21). We generated and recently characterized a novel strain of transgenic mice in which the AML1/ETO cDNA was inserted into the Ly-6A gene that encodes Sca1, a well-characterized marker of murine hematopoietic stem cells. Unexpectedly, transgene expression assessed by flow cytometry was significantly lower than predicted in lymphocytes from these mice. We have confirmed this finding at the mRNA level and suggest that this phenotype is a consequence of dominant inhibition of transgene expression by AML1/ETO. The dominant negative characteristics of AML1/ETO may be important for AML pathogenesis and may provide a molecular target for therapeutic intervention.

Acute Disease↗
PubMed2001

Runt-related gene 2 in endothelial cells: inducible expression and specific regulation of cell migration and invasion.

Understanding the regulation of endothelial cell (EC) gene expression has important implications for angiogenesis, tumor growth, and metastasis. The transcription factor runt-related gene 2 (RUNX2)/core binding factoralpha-1/acute myeloid leukemia 3/polyoma enhancer-binding protein 2alphaA/osteoblast-specific transcription factor 2 regulates osteoblast differentiation, increases lymphomagenesis in transgenic mice, and is expressed in murine ECs. Here, we report on RUNX2 expression in human bone marrow EC (HBME-1) and its role in EC differentiation. Expression of RUNX2 occurred in HBME-1 cultured on extracellular matrix (ECM) substrates that stimulate in vitro differentiation (tube formation). Neutralizing anti-insulin-like growth factor (IGF)-I-receptor antibody inhibited tube formation as well as activation of RUNX2 expression in HBME-1 cultured on ECM. IGF-I treatment also increased both RUNX2 mRNA and protein expression. HBME-1 transfectants expressing dominant-negative (DN) RUNX were established to address the role of RUNX2 in these processes. HBME/DN cells exhibited reduced tube formation activity relative to control transfectants and less ability to growth arrest and differentiate on ECM. DNRUNX expression also inhibited HBME-1 migration and invasion, which are necessary for tube formation. The urokinase-type plasminogen activator and membrane-type MMP-1 genes were consistently down-regulated in DNRUNX transfectants. The results suggest that RUNX2 is important in IGF-I and ECM-regulated EC migration and differentiation. RUNX2 effects on HBME-1 migration and invasion may occur through activation of protease expression, events that regulate angiogenesis, and tumor growth.

Animals↗
PubMed2003

Osteoblast-related transcription factors Runx2 (Cbfa1/AML3) and MSX2 mediate the expression of bone sialoprotein in human metastatic breast cancer cells.

Human breast cancers are known to preferentially metastasize to skeletal sites, however, the mechanisms that mediate the skeletal preference (orthotropism) of specific types of cancers remains poorly understood. There is a significant clinical correlation between the expression of bone sialoprotein (BSP) and skeletal metastasis of breast cancers. Our laboratory, as well as others, have proposed the concept that skeletal selective metastasis and associated disease may be attributable to a mimicry of skeletal cellular phenotypes by metastasizing cancer cells. We hypothesize that breast cancer cell expression of phenotypic properties of skeletal cell types, including BSP as one component of that phenotype, is the result of ectopic expression or activity of one or more central transcriptional regulators of bone cell gene expression. To test this hypothesis, we examined the molecular mechanisms that regulate bsp expression in human breast cancer cell lines with previously characterized metastatic potentials. Our results demonstrate that the majority of the distal bsp promoter sequences act to repress BSP expression in cancer cells and that most of the promoter activity resides in the proximal -110 bp of the bsp promoter. In this region, we identified a putative Runx binding element providing a basis for a mechanism for skeletal gene activation. Our results demonstrate that Runx2 is ectopically expressed in breast cancer cells and that one isoform of Runx2 can activate bsp expression in these cells. In addition, we observe that bsp expression is additionally regulated by the homeodomain factor Msx2, another regulator of osteoblast-associated genes. Thus, this is the first report of osteoblast-related transcription factors being expressed in human breast cancer cells and provides a component of a mechanism that may explain the osteoblastic phenotype of human breast cancer cells that preferentially metastasize to bone.

Breast Neoplasms↗
PubMed2003

Runx2/Cbfa1 functions: diverse regulation of gene transcription by chromatin remodeling and co-regulatory protein interactions.

Development of the osteoblast phenotype requires transcriptional mechanisms that regulate induction of a program of temporally expressed genes. Key components of gene activation, repression, and responsiveness to physiologic mediators require remodeling of the chromatin structure of a gene that renders promoter elements competent for the assembly of macromolecular transcriptional complexes. Here we review evidence that the Runx transcription factors support tissue-specific gene expression and bone formation by contributing to promoter structure, chromatin remodeling, and the integration of independent signaling pathways. In addition, we discuss the role of Runx2 in both activation and negative regulation of gene promoters (osteocalcin, bone sialoprotein, and Runx2/Cbfa1) in relation to the interaction of Runx with co-regulatory proteins in distinct subnuclear foci. The modifications in chromatin organization and transcription of the osteocalcin gene that are influenced by the activities of Runx2/Cbfa1 mediated by interacting proteins (YAP, TLE, SMAD, C/EBP) are emphasized. These functional properties of Runx2 provide novel insights into the requirements for multiple levels of transcriptional control within the context of nuclear architecture to support the convergence of regulatory signals that control tissue-specific gene expression.

Animals↗
PubMed2003

Temporal and spatial parameters of skeletal gene expression: targeting RUNX factors and their coregulatory proteins to subnuclear domains.

Key components of the basal transcription machinery and several tissue-specific transcription factor complexes are functionally compartmentalized as specialized subnuclear domains. We have identified a unique 31-38 amino acid targeting signal (NMTS) that directs the Runx (Cbfa/AML) transcription factors to distinct nuclear matrix-(NM) associated sites within the nucleus that support gene expression. Our determination of the NMTS crystal structure, yeast 2 hybrid screens to identify NM interacting proteins, and in situ colocalization studies with Runx interacting factors (YAP, Smad, TLE) suggest that localization of Runx transcription factors at intranuclear sites facilitates the assembly and activity of regulatory complexes that mediate activation and suppression of target genes. Mice homozygous for the deletion of the intranuclear Runx2 targeting signal in a homologous recombination (Runx2 deltaC) do not form bone due to maturational arrest of osteoblasts, demonstrating the importance of fidelity of subnuclear localization for tissue-differentiating activity. These results provide evidence that Runx2 subnuclear targeting and the associated regulatory functions are essential for a spatiotemporal placement that facilitates activation of Runx-dependent genes involved in tissue differentiation during embryonic development.

Animals↗
PubMed2004

Nuclear microenvironments: an architectural platform for the convergence and integration of transcriptional regulatory signals.

Functional interrelationships between the intranuclear organization of nucleic acids and regulatory proteins are obligatory for fidelity of transcriptional activation and repression. In this article, using the Runx/AML/Cbfa transcription factors as a paradigm for linkage between nuclear structure and gene expression we present an overview of growing insight into the dynamic organization and assembly of regulatory machinery for gene expression at microenvironments within the nucleus. We address contributions of nuclear microenvironments to the convergence and integration of regulatory signals that mediate transcription by supporting the combinatorial assembly of regulatory complexes.

Active Transport, Cell Nucleus↗
PubMed1993

Molecular basis of the t(8;21) translocation in acute myeloid leukaemia.

The t(8;21) translocation is one of the most frequent chromosomal abnormalities in acute myeloid leukaemia and results in gene fusion between AML1 on chromosome 21 and MTG8 (= ETO or CDR) on chromosome 8. AML1 contains a region of sequence homology to the Drosophila runt gene and the mouse polyomavirus enhancer binding protein PEBP2 alpha gene. The rearrangement occurs within a specific intron of the AML1 gene and results in the formation of a chimaeric protein with the consistent feature that the region of sequence homology of AML1 is fused with almost the entire MTG8 protein. MTG8 (ETO, CDR) is predicted to be a transcription activation factor from its sequence with zinc-finger motifs and proline-rich domains. Thus the rearrangement is a fusion between two probable transcription activation factors.

Amino Acid Sequence↗
PubMed2004

AML1/Runx1 recruits calcineurin to regulate granulocyte macrophage colony-stimulating factor by Ets1 activation.

Acute myeloid leukemia 1 (AML1), also denoted Runx1, is a transcription factor essential for hematopoiesis, and the AML1 gene is the most common target of chromosomal translocations in human leukemias. AML1 binds to sequences present in the regulatory regions of a number of hematopoiesis-specific genes, including certain cytokines such as granulocyte macrophage colony-stimulating factor (GM-CSF) up-regulated after T cell receptor stimulation. Here we show that both subunits of the Ca(2+)/calmodulin-dependent protein phosphatase calcineurin (CN), which is activated upon T cell receptor stimulation, interact directly with the N-terminal runt homology domain-containing part of AML1. The regulatory CN subunit binds AML1 with a higher affinity and in addition also interacts with the isolated runt homology domain. The related Runx2 transcription factor, which is essential for bone formation, also interacts with CN. A constitutively active derivative of CN is shown to activate synergistically the GM-CSF promoter/enhancer together with AML1 or Runx2. We also provide evidence that relief of the negative effect of the AML1 sites is important for Ca(2+) activation of the GM-CSF promoter/enhancer and that AML1 overexpression increases this Ca(2+) activation. Both subunits of CN interact with AML1 in coimmunoprecipitation analyses, and confocal microscopy analysis of cells expressing fluorescence-tagged protein derivatives shows that CN can be recruited to the nucleus by AML1 in vivo. Mutant analysis of the GM-CSF promoter shows that the Ets1 binding site of the promoter is essential for the synergy between AML1 and CN in Jurkat T cells. Analysis of the effects of inhibitors of the protein kinase glycogen synthase kinase-3beta and in vitro phosphorylation/dephosphorylation analysis of Ets1 suggest that glycogen synthase kinase-3beta-phosphorylated Ets1 is a target of AML1-recruited CN phosphatase at the GM-CSF promoter.

Animals↗
PubMed2006

RUNX1 (AML-1) and RUNX2 (AML-3) cooperate with prostate-derived Ets factor to activate transcription from the PSA upstream regulatory region.

The RUNX transcription factors (RUNX1, RUNX2, and RUNX3) play essential roles in hematopoiesis and skeletal development. Consistent with these roles in differentiation and cell cycle, the activity of both RUNX1 and RUNX3 is perturbed in cancer. To determine a role for the RUNX factors in prostate biology, we investigated the expression of RUNX factors in prostate epithelial cell lines and normal prostate tissue. RUNX1, RUNX2, and RUNX3 were expressed in both normal prostate tissue and an immortalized, non-transformed cell line. We found that prostate cancer-derived cell lines expressed RUNX1 and RUNX2, but not RUNX3. Next, we sought to identify prostate-specific genes whose expression could be regulated by RUNX proteins. Four consensus RUNX sites are located within the prostate-specific antigen (PSA) regulatory region. Chromatin immunoprecipitation (ChIP) analysis showed that RUNX1 is specifically bound to the PSA regulatory region in LNCaP cells. RUNX1 and RUNX2 activated the PSA regulatory region alone or cooperatively with prostate-derived ETS factor (PDEF) and RUNX1 physically associated with PDEF. Taken together, our results suggest that RUNX factors participate in prostate epithelial cell function and cooperate with an Ets transcription factor to regulate PSA gene expression.

Base Sequence↗
PubMed2005

Overlapping expression of Runx1(Cbfa2) and Runx2(Cbfa1) transcription factors supports cooperative induction of skeletal development.

Identifying the genetic pathways that regulate skeletal development is necessary to correct a variety of cartilage and bone abnormalities. The Runx family of transcription factors play a fundamental role in organ development and cell differentiation. Initial studies have shown that both Runx1 and Runx2 are expressed in pre-chondrogenic mesenchyme of the developing embryo at E12.5. Abrogation of the Runx2 gene completely inhibits bone formation yet the cartilage anlagen in these mice is fully formed. In the present study, we hypothesized that Runx1 may compensate for the lack of Runx2 in vivo to induce the early stages of skeletal formation and development. Histologic beta-gal stained sections using the Runx1(+/-)-Lac-Z mice demonstrate Runx1 promoter activity in pre-chondrocytic cell populations. In situ hybridization using Runx1 and Runx2 specific probes indicate that both factors are expressed in mesenchymal stem cell progenitors during early embryonic development. During later stages of mouse skeletal formation, Runx1 is excluded from the hypertrophic cartilage while Runx2 is present in these matured chondrocyte populations. Quantification of Runx expression by real time RT-PCR and Western blot analyses reveals that Runx1 and Runx2 are differentially modulated during embryogenesis suggesting a temporal role for each of these transcriptional regulators during skeletal formation. We provide evidence that haploinsufficiency results in normal appearing embryo skeletons of heterozygote Runx2 and Runx1 mutant mouse models; however, a delay in bone formation was identified in the calvarium. In summary, our results support a function for Runx1 and Runx2 during skeletal development with a possible role for Runx1 in mediating early events of endochondral and intramembranous bone formation, while Runx2 is a potent inducer of late stages of chondrocyte and osteoblast differentiation.

Animals↗