SWI/SNF chromatin remodeling complex is obligatory for BMP2-induced, Runx2-dependent skeletal gene expression that controls osteoblast differentiation
AuthorsYoung, Daniel W.
Van Wijnen, Andre J.
Montecino, Martin A.
Stein, Gary S.
Stein, Janet L.
Imbalzano, Anthony N.
Lian, Jane B.
UMass Chan AffiliationsDepartment of Cell Biology
Graduate School of Biomedical Sciences
Document TypeJournal Article
KeywordsAlkaline Phosphatase; Animals; Bone Morphogenetic Proteins; *Cell Differentiation; Cell Line; *Chromatin Assembly and Disassembly; Core Binding Factor Alpha 1 Subunit; Cytoskeletal Proteins; DNA-Binding Proteins; Gene Expression; Humans; Mice; Oligonucleotide Array Sequence Analysis; Osteoblasts; Protein Binding; Protein Subunits; Rats; Transcription Factor AP-2; Transcription Factors; Transforming Growth Factor beta
Medicine and Health Sciences
MetadataShow full item record
AbstractDevelopment of bone tissue requires maturation of osteoblasts from mesenchymal precursors. BMP2, a member of the TGFbeta superfamily, and the Runx2 (AML3/Cbfa1) transcription factor, a downstream BMP2 effector, are regulatory signals required for osteoblast differentiation. While Runx2 responsive osteogenic gene expression has been functionally linked to alterations in chromatin structure, the factors that govern this chromatin remodeling remain to be identified. Here, we address the role of the SWI/SNF chromatin remodeling enzymes in BMP2-induced, Runx2-dependent development of the osteoblast phenotype. For these studies, we have examined calvarial cells from wild-type (WT) mice and mice that are homozygous for the Runx2 null allele, as well as the C2C12 model of BMP2-induced osteogenesis. By the analysis of microarray data, we find that several components of the SWI/SNF complex are regulated during BMP2-mediated osteoblast differentiation. Brg1 is an essential DNA dependent ATPase subunit of the SWI/SNF complex. Thus, functional studies were carried out using a fibroblast cell line that conditionally expresses a mutant Brg1 protein, which exerts a dominant negative effect on SWI/SNF function. Our findings demonstrate that SWI/SNF is required for BMP2-induced expression of alkaline phosphatase (APase), an early marker reflecting Runx2 control of osteoblast differentiation. In addition, Brg1 is expressed in cells within the developing skeleton of the mouse embryo as well as in osteoblasts ex vivo. Taken together these results support the concept that BMP2-mediated osteogenesis requires Runx2, and demonstrates that initiation of BMP2-induced, Runx2-dependent skeletal gene expression requires SWI/SNF chromatin remodeling complexes.
SourceJ Cell Biochem. 2005 Mar 1;94(4):720-30. Link to article on publisher's site
Permanent Link to this Itemhttp://hdl.handle.net/20.500.14038/34052
Related ResourcesLink to Article in PubMed
Showing items related by title, author, creator and subject.
Dynamic Regulation at the Neuronal Plasma Membrane: Novel Endocytic Mechanisms Control Anesthetic-Activated Potassium Channels and Amphetamine-Sensitive Dopamine Transporters: A DissertationGabriel, Luke R. (2013-06-13)Endocytic trafficking dynamically regulates neuronal plasma membrane protein presentation and activity, and plays a central role in excitability and plasticity. Over the course of my dissertation research I investigated endocytic mechanisms regulating two neuronal membrane proteins: the anesthetic-activated potassium leak channel, KCNK3, as well as the psychostimulant-sensitive dopamine transporter (DAT). My results indicate that KCNK3 internalizes in response to Protein Kinase C (PKC) activation, using a novel pathway that requires the phosphoserine binding protein, 14-3-3β, and demonstrates for the first time regulated KCNK3 channel trafficking in neurons. Additionally, PKC-mediated KCNK3 trafficking requires a non-canonical endocytic motif, which is shared exclusively between KCNK3 and sodium-dependent neurotransmitter transporters, such as DAT. DAT trafficking studies in intact ex vivo adult striatal slices indicate that DAT endocytic trafficking has both dynamin-dependent and –independent components. Moreover, DAT segregates into two populations at the neuronal plasma membrane: trafficking-competent and -incompetent. Taken together, these results demonstrate that novel, non-classical endocytic mechanisms dynamically control the plasma membrane presentation of these two important neuronal proteins.
Selective interaction of JNK protein kinase isoforms with transcription factorsGupta, Shashi; Barrett, Tamera; Whitmarsh, Alan J.; Cavanagh, Julie; Sluss, Hayla Karen; Derijard, Benoit; Davis, Roger J. (1996-06-03)The JNK protein kinase is a member of the MAP kinase group that is activated in response to dual phosphorylation on threonine and tyrosine. Ten JNK isoforms were identified in human brain by molecular cloning. These protein kinases correspond to alternatively spliced isoforms derived from the JNK1, JNK2 and JNK3 genes. The protein kinase activity of these JNK isoforms was measured using the transcription factors ATF2, Elk-1 and members of the Jun family as substrates. Treatment of cells with interleukin-1 (IL-1) caused activation of the JNK isoforms. This activation was blocked by expression of the MAP kinase phosphatase MKP-1. Comparison of the binding activity of the JNK isoforms demonstrated that the JNK proteins differ in their interaction with ATF2, Elk-1 and Jun transcription factors. Individual members of the JNK group may therefore selectively target specific transcription factors in vivo.
Role of the Raf/mitogen-activated protein kinase pathway in p21ras desensitizationKlarlund, Jes K.; Cherniack, Andrew D.; McMahon, Martin; Czech, Michael P. (1996-07-12)Desensitization of p21(ras) after stimulation of cells by growth factors and phorbol 12-myristate 13-acetate (PMA) correlates with hyperphosphorylation of the guanine nucleotide exchange factor Son-of-sevenless (Sos) and its dissociation from the adaptor protein Grb2 (Cherniack, A., Klarlund, J. K., Conway, B. R., and Czech, M. P. (1995) J. Biol. Chem. 270, 1485-1488). To test the role of the Raf/mitogen-activated protein (MAP) kinase pathway, we utilized cells expressing a chimera composed of the catalytic domain of p74Raf-1 and the hormone binding domain of the estradiol receptor (DeltaRaf-1:ER). Estradiol markedly stimulated DeltaRaf-1:ER and the downstream MEK and MAP kinases in these cells as well as Sos phosphorylation. However, the dissociation of Grb2 from Sos observed in response to PMA was not apparent upon DeltaRaf-1:ER activation. Furthermore, stimulation of DeltaRaf-1:ER did not impair GTP loading of p21(ras) in response to platelet-derived growth factor or epidermal growth factor. We conclude that activation of the Raf/MAP kinase pathway alone in these cells is insufficient to cause disassembly of Sos from Grb2 or to interrupt the ability of Sos to catalyze activation of p21(ras).