1
|
Gámez B, Rodríguez-Carballo E, Graupera M, Rosa JL, Ventura F. Class I PI-3-Kinase Signaling Is Critical for Bone Formation Through Regulation of SMAD1 Activity in Osteoblasts. J Bone Miner Res 2016; 31:1617-30. [PMID: 26896753 DOI: 10.1002/jbmr.2819] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 02/16/2016] [Accepted: 02/18/2016] [Indexed: 12/21/2022]
Abstract
Bone formation and homeostasis is carried out by osteoblasts, whose differentiation and activity are regulated by osteogenic signaling networks. A central mediator of these inputs is the lipid kinase phosphatidylinositol 3-kinase (PI3K). However, at present, there are no data on the specific role of distinct class IA PI3K isoforms in bone biology. Here, we performed osteoblast-specific deletion in mice to show that both p110α and p110β isoforms are required for survival and differentiation and function of osteoblasts and thereby control bone formation and postnatal homeostasis. Impaired osteogenesis arises from increased GSK3 activity and a depletion of SMAD1 protein levels in PI3K-deficient osteoblasts. Accordingly, pharmacological inhibition of GSK3 activity or ectopic expression of SMAD1 or SMAD5 normalizes bone morphogenetic protein (BMP) transduction and osteoblast differentiation. Together, these results identify the PI3K-GSK3-SMAD1 axis as a central node integrating multiple signaling networks that govern bone formation and homeostasis. © 2016 American Society for Bone and Mineral Research.
Collapse
Affiliation(s)
- Beatriz Gámez
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Barcelona, Spain
| | - Edgardo Rodríguez-Carballo
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Barcelona, Spain
| | - Mariona Graupera
- Vascular Signaling Laboratory, Catalan Institute of Oncology, IDIBELL, L'Hospitalet de Llobregat, Barcelona, Spain
| | - José Luis Rosa
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Barcelona, Spain
| | - Francesc Ventura
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Barcelona, Spain
| |
Collapse
|
2
|
Aquino-Martínez R, Rodríguez-Carballo E, Gámez B, Artigas N, Carvalho-Lobato P, Manzanares-Céspedes MC, Rosa JL, Ventura F. Mesenchymal Stem Cells Within Gelatin/CaSO4 Scaffolds Treated Ex Vivo with Low Doses of BMP-2 and Wnt3a Increase Bone Regeneration. Tissue Eng Part A 2016; 22:41-52. [DOI: 10.1089/ten.tea.2015.0181] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Rubén Aquino-Martínez
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - Edgardo Rodríguez-Carballo
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - Beatriz Gámez
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - Natalia Artigas
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - Patricia Carvalho-Lobato
- Unitat d'Anatomia i Embriologia Humana, Departament de Patologia i Terapèutica Experimental, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - Maria Cristina Manzanares-Céspedes
- Unitat d'Anatomia i Embriologia Humana, Departament de Patologia i Terapèutica Experimental, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - Jose Luis Rosa
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - Francesc Ventura
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| |
Collapse
|
3
|
Rodríguez-Carballo E, Gámez B, Méndez-Lucas A, Sánchez-Freutrie M, Zorzano A, Bartrons R, Alcántara S, Perales JC, Ventura F. p38α function in osteoblasts influences adipose tissue homeostasis. FASEB J 2014; 29:1414-25. [PMID: 25550462 DOI: 10.1096/fj.14-261891] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 11/24/2014] [Indexed: 12/19/2022]
Abstract
The skeleton acts as an endocrine organ that regulates energy metabolism and calcium and phosphorous homeostasis through the secretion of osteocalcin (Oc) and fibroblast growth factor 23 (FGF23). However, evidence suggests that osteoblasts secrete additional unknown factors that contribute to the endocrine function of bone. To search for these additional factors, we generated mice with a conditional osteoblast-specific deletion of p38α MAPK known to display profound defects in bone homeostasis. Herein, we show that impaired osteoblast function is associated with a strong decrease in body weight and adiposity (P < 0.01). The differences in adiposity were not associated with diminished caloric intake, but rather reflected 20% increased energy expenditure and the up-regulation of uncoupling protein-1 (Ucp1) in white adipose tissue (WAT) and brown adipose tissue (BAT) (P < 0.05). These alterations in lipid metabolism and energy expenditure were correlated with a decrease in the blood levels of neuropeptide Y (NPY) (40% lower) rather than changes in the serum levels of insulin, Oc, or FGF23. Among all Npy-expressing tissues, only bone and primary osteoblasts showed a decline in Npy expression (P < 0.01). Moreover, the intraperitoneal administration of recombinant NPY partially restored the WAT weight and adipocyte size of p38α-deficient mice (P < 0.05). Altogether, these results further suggest that, in addition to Oc, other bone-derived signals affect WAT and energy expenditure contributing to the regulation of energy metabolism.
Collapse
Affiliation(s)
- Edgardo Rodríguez-Carballo
- *Departamente de Ciències Fisiològiques II and and Departament de Patologia i Terapèutica Experimental, Universitat de Barcelona, Institut d'Investigació Biomèdica de Bellvitge, L'Hospitalet de Llobregat, Barcelona, Spain; Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Barcelona, Spain; Institute for Research in Biomedicine, Barcelona, Spain; and Centro de Investigación Biomédica en Red (CIBER) de Diabetes y Enfermedades Metabólicas Asociadas, Instituto de Salud Carlos III, Madrid, Spain
| | - Beatriz Gámez
- *Departamente de Ciències Fisiològiques II and and Departament de Patologia i Terapèutica Experimental, Universitat de Barcelona, Institut d'Investigació Biomèdica de Bellvitge, L'Hospitalet de Llobregat, Barcelona, Spain; Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Barcelona, Spain; Institute for Research in Biomedicine, Barcelona, Spain; and Centro de Investigación Biomédica en Red (CIBER) de Diabetes y Enfermedades Metabólicas Asociadas, Instituto de Salud Carlos III, Madrid, Spain
| | - Andrés Méndez-Lucas
- *Departamente de Ciències Fisiològiques II and and Departament de Patologia i Terapèutica Experimental, Universitat de Barcelona, Institut d'Investigació Biomèdica de Bellvitge, L'Hospitalet de Llobregat, Barcelona, Spain; Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Barcelona, Spain; Institute for Research in Biomedicine, Barcelona, Spain; and Centro de Investigación Biomédica en Red (CIBER) de Diabetes y Enfermedades Metabólicas Asociadas, Instituto de Salud Carlos III, Madrid, Spain
| | - Manuela Sánchez-Freutrie
- *Departamente de Ciències Fisiològiques II and and Departament de Patologia i Terapèutica Experimental, Universitat de Barcelona, Institut d'Investigació Biomèdica de Bellvitge, L'Hospitalet de Llobregat, Barcelona, Spain; Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Barcelona, Spain; Institute for Research in Biomedicine, Barcelona, Spain; and Centro de Investigación Biomédica en Red (CIBER) de Diabetes y Enfermedades Metabólicas Asociadas, Instituto de Salud Carlos III, Madrid, Spain
| | - Antonio Zorzano
- *Departamente de Ciències Fisiològiques II and and Departament de Patologia i Terapèutica Experimental, Universitat de Barcelona, Institut d'Investigació Biomèdica de Bellvitge, L'Hospitalet de Llobregat, Barcelona, Spain; Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Barcelona, Spain; Institute for Research in Biomedicine, Barcelona, Spain; and Centro de Investigación Biomédica en Red (CIBER) de Diabetes y Enfermedades Metabólicas Asociadas, Instituto de Salud Carlos III, Madrid, Spain
| | - Ramon Bartrons
- *Departamente de Ciències Fisiològiques II and and Departament de Patologia i Terapèutica Experimental, Universitat de Barcelona, Institut d'Investigació Biomèdica de Bellvitge, L'Hospitalet de Llobregat, Barcelona, Spain; Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Barcelona, Spain; Institute for Research in Biomedicine, Barcelona, Spain; and Centro de Investigación Biomédica en Red (CIBER) de Diabetes y Enfermedades Metabólicas Asociadas, Instituto de Salud Carlos III, Madrid, Spain
| | - Soledad Alcántara
- *Departamente de Ciències Fisiològiques II and and Departament de Patologia i Terapèutica Experimental, Universitat de Barcelona, Institut d'Investigació Biomèdica de Bellvitge, L'Hospitalet de Llobregat, Barcelona, Spain; Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Barcelona, Spain; Institute for Research in Biomedicine, Barcelona, Spain; and Centro de Investigación Biomédica en Red (CIBER) de Diabetes y Enfermedades Metabólicas Asociadas, Instituto de Salud Carlos III, Madrid, Spain
| | - José Carlos Perales
- *Departamente de Ciències Fisiològiques II and and Departament de Patologia i Terapèutica Experimental, Universitat de Barcelona, Institut d'Investigació Biomèdica de Bellvitge, L'Hospitalet de Llobregat, Barcelona, Spain; Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Barcelona, Spain; Institute for Research in Biomedicine, Barcelona, Spain; and Centro de Investigación Biomédica en Red (CIBER) de Diabetes y Enfermedades Metabólicas Asociadas, Instituto de Salud Carlos III, Madrid, Spain
| | - Francesc Ventura
- *Departamente de Ciències Fisiològiques II and and Departament de Patologia i Terapèutica Experimental, Universitat de Barcelona, Institut d'Investigació Biomèdica de Bellvitge, L'Hospitalet de Llobregat, Barcelona, Spain; Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Barcelona, Spain; Institute for Research in Biomedicine, Barcelona, Spain; and Centro de Investigación Biomédica en Red (CIBER) de Diabetes y Enfermedades Metabólicas Asociadas, Instituto de Salud Carlos III, Madrid, Spain
| |
Collapse
|
4
|
Artigas N, Ureña C, Rodríguez-Carballo E, Rosa JL, Ventura F. Mitogen-activated protein kinase (MAPK)-regulated interactions between Osterix and Runx2 are critical for the transcriptional osteogenic program. J Biol Chem 2014; 289:27105-27117. [PMID: 25122769 PMCID: PMC4175347 DOI: 10.1074/jbc.m114.576793] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 08/06/2014] [Indexed: 11/06/2022] Open
Abstract
The transcription factors Runx2 and Osx (Osterix) are required for osteoblast differentiation and bone formation. Runx2 expression occurs at early stages of osteochondroprogenitor determination, followed by Osx induction during osteoblast maturation. We demonstrate that coexpression of Osx and Runx2 leads to cooperative induction of expression of the osteogenic genes Col1a1, Fmod, and Ibsp. Functional interaction of Osx and Runx2 in the regulation of these promoters is mediated by enhancer regions with adjacent Sp1 and Runx2 DNA-binding sites. These enhancers allow formation of a cooperative transcriptional complex, mediated by the binding of Osx and Runx2 to their specific DNA promoter sequences and by the protein-protein interactions between them. We also identified the domains involved in the interaction between Osx and Runx2. These regions contain the amino acids in Osx and Runx2 known to be phosphorylated by p38 and ERK MAPKs. Inhibition of p38 and ERK kinase activities or mutation of their known phosphorylation sites in Osx or Runx2 strongly disrupts their physical interaction and cooperative transcriptional effects. Altogether, our results provide a molecular description of a mechanism for Osx and Runx2 transcriptional cooperation that is subject to further regulation by MAPK-activating signals during osteogenesis.
Collapse
Affiliation(s)
- Natalia Artigas
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, L'Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), E-08907 L'Hospitalet de Llobregat, Spain
| | - Carlos Ureña
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, L'Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), E-08907 L'Hospitalet de Llobregat, Spain
| | - Edgardo Rodríguez-Carballo
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, L'Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), E-08907 L'Hospitalet de Llobregat, Spain
| | - José Luis Rosa
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, L'Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), E-08907 L'Hospitalet de Llobregat, Spain
| | - Francesc Ventura
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, L'Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), E-08907 L'Hospitalet de Llobregat, Spain.
| |
Collapse
|
5
|
Rodríguez-Carballo E, Gámez B, Sedó-Cabezón L, Sánchez-Feutrie M, Zorzano A, Manzanares-Céspedes C, Rosa JL, Ventura F. The p38α MAPK function in osteoprecursors is required for bone formation and bone homeostasis in adult mice. PLoS One 2014; 9:e102032. [PMID: 25007355 PMCID: PMC4090229 DOI: 10.1371/journal.pone.0102032] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 06/13/2014] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND p38 MAPK activity plays an important role in several steps of the osteoblast lineage progression through activation of osteoblast-specific transcription factors and it is also essential for the acquisition of the osteoblast phenotype in early development. Although reports indicate p38 signalling plays a role in early skeletal development, its specific contributions to adult bone remodelling are still to be clarified. METHODOLOGY/PRINCIPAL FINDINGS We evaluated osteoblast-specific deletion of p38α to determine its significance in early skeletogenesis, as well as for bone homeostasis in adult skeleton. Early p38α deletion resulted in defective intramembranous and endochondral ossification in both calvaria and long bones. Mutant mice showed reduction of trabecular bone volume in distal femurs, associated with low trabecular thickness. In addition, knockout mice also displayed decreased femoral cortical bone volume and thickness. Deletion of p38α did not affect osteoclast function. Yet it impaired osteoblastogenesis and osteoblast maturation and activity through decreased expression of osteoblast-specific transcription factors and their targets. Furthermore, the inducible Cre system allowed us to control the onset of p38α disruption after birth by removal of doxycycline. Deletion of p38α at three or eight weeks postnatally led to significantly lower trabecular and cortical bone volume after 6 or 12 months. CONCLUSIONS Our data demonstrates that, in addition to early skeletogenesis, p38α is essential for osteoblasts to maintain their function in mineralized adult bone, as bone anabolism should be sustained throughout life. Moreover, our data also emphasizes that clinical development of p38 inhibitors should take into account their potential bone effects.
Collapse
Affiliation(s)
- Edgardo Rodríguez-Carballo
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - Beatriz Gámez
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - Lara Sedó-Cabezón
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - Manuela Sánchez-Feutrie
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Barcelona, Spain
| | - Antonio Zorzano
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Barcelona, Spain
| | - Cristina Manzanares-Céspedes
- Departament de Patologia i Terapèutica Experimental, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - José Luis Rosa
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - Francesc Ventura
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
- * E-mail:
| |
Collapse
|
6
|
Gámez B, Rodríguez-Carballo E, Bartrons R, Rosa JL, Ventura F. MicroRNA-322 (miR-322) and its target protein Tob2 modulate Osterix (Osx) mRNA stability. J Biol Chem 2013; 288:14264-14275. [PMID: 23564456 DOI: 10.1074/jbc.m112.432104] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Osteogenesis depends on a coordinated network of signals and transcription factors such as Runx2 and Osterix. Recent evidence indicates that microRNAs (miRNAs) act as important post-transcriptional regulators in a large number of processes, including osteoblast differentiation. In this study, we performed miRNA expression profiling and identified miR-322, a BMP-2-down-regulated miRNA, as a regulator of osteoblast differentiation. We report miR-322 gain- and loss-of-function experiments in C2C12 and MC3T3-E1 cells and primary cultures of murine bone marrow-derived mesenchymal stem cells. We demonstrate that overexpression of miR-322 enhances BMP-2 response, increasing the expression of Osx and other osteogenic genes. Furthermore, we identify Tob2 as a target of miR-322, and we characterize the specific Tob2 3'-UTR sequence bound by miR-322 by reporter assays. We demonstrate that Tob2 is a negative regulator of osteogenesis that binds and mediates degradation of Osx mRNA. Our results demonstrate a new molecular mechanism controlling osteogenesis through the specific miR-322/Tob2 regulation of specific target mRNAs. This regulatory circuit provides a clear example of a complex miRNA-transcription factor network for fine-tuning the osteoblast differentiation program.
Collapse
Affiliation(s)
- Beatriz Gámez
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, and L'Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), E-08907 L'Hospitalet de Llobregat, Barcelona, Spain
| | - Edgardo Rodríguez-Carballo
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, and L'Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), E-08907 L'Hospitalet de Llobregat, Barcelona, Spain
| | - Ramon Bartrons
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, and L'Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), E-08907 L'Hospitalet de Llobregat, Barcelona, Spain
| | - José Luis Rosa
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, and L'Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), E-08907 L'Hospitalet de Llobregat, Barcelona, Spain
| | - Francesc Ventura
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, and L'Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), E-08907 L'Hospitalet de Llobregat, Barcelona, Spain.
| |
Collapse
|
7
|
Rodríguez-Carballo E, Ulsamer A, Susperregui ARG, Manzanares-Céspedes C, Sánchez-García E, Bartrons R, Rosa JL, Ventura F. Conserved regulatory motifs in osteogenic gene promoters integrate cooperative effects of canonical Wnt and BMP pathways. J Bone Miner Res 2011; 26:718-29. [PMID: 20878775 DOI: 10.1002/jbmr.260] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Osteoblast differentiation depends on the coordinated network of evolutionary conserved transcription factors during bone formation and homeostasis. Evidence indicates that bone morphogenetic protein (BMP) and Wnt proteins regulate several steps of skeletal development. Here, we provide a molecular description of the cooperative effects of BMP and Wnt canonical pathway on the expression of the early osteogenic genes Dlx5, Msx2, and Runx2 in C2C12 cells, primary cultures of bone marrow-mesenchymal stem cells, and organotypic calvarial cultures. Coordinated regulation of these genes leads to the cooperative activation of their downstream osteogenic target gene osterix. Induction of these genes is mediated through enhancer regions with an evolutionary conserved structure encompassing both Smad and TCF/LEF1 DNA-binding sites. Formation of a cooperative complex is mediated through DNA binding of Smads and TCF4/β-catenin to their cognate sequences, as well as protein-protein interactions between them. The formation of these cooperative transcriptional complexes results in a more efficient recruitment of coactivators such as p300. We propose that evolutionary conserved regulatory regions in specific osteogenic master genes are key integrative modules during osteogenesis.
Collapse
Affiliation(s)
- Edgardo Rodríguez-Carballo
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, IDIBELL, L'Hospitalet de Llobregat, Spain
| | | | | | | | | | | | | | | |
Collapse
|
8
|
Susperregui ARG, Gamell C, Rodríguez-Carballo E, Ortuño MJ, Bartrons R, Rosa JL, Ventura F. Noncanonical BMP signaling regulates cyclooxygenase-2 transcription. Mol Endocrinol 2011; 25:1006-17. [PMID: 21436263 DOI: 10.1210/me.2010-0515] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Activation of p38 MAPK has been shown to be relevant for a number of bone morphogenetic protein (BMP) physiological effects. We report here the involvement of noncanonical phosphorylated mothers against decapentaplegic (Smad) signaling in the transcriptional induction of Cox2 (Ptgs2) by BMP-2 in mesenchymal cells and organotypic calvarial cultures. We demonstrate that different regulatory elements are required for regulation of Cox2 expression by BMP-2: Runt-related transcription factor-2 and cAMP response element sites are essential, whereas a GC-rich Smad binding element is important for full responsiveness. Efficient transcriptional activation requires cooperation between transcription factors because mutation of any element results in a strong decrease of BMP-2 responsiveness. BMP-2 activation of p38 leads to increased recruitment of activating transcription factor-2, Runx2, Smad, and coactivators such as p300 at the responsive sites in the Cox2 proximal promoter. We demonstrate, by either pharmacological or genetic analysis, that maximal BMP-2 effects on Cox2 and JunB expression require the function of p38 and its downstream effector mitogen/stress-activated kinase 1. Altogether our results strongly suggest that cooperative effects between canonical and noncanonical BMP signaling allow the fine-tuning of BMP transcriptional responses on specific target genes.
Collapse
Affiliation(s)
- Antonio R G Susperregui
- Departament de Ciències Fisiològiques II, Bellvitge Biomedical Research Institute, C/ Feixa Llarga s/n., L'Hospitalet de Llobregat, Universitat de Barcelona, E-08907 Barcelona, Spain
| | | | | | | | | | | | | |
Collapse
|
9
|
Ortuño MJ, Ruiz-Gaspà S, Rodríguez-Carballo E, Susperregui ARG, Bartrons R, Rosa JL, Ventura F. p38 regulates expression of osteoblast-specific genes by phosphorylation of osterix. J Biol Chem 2010; 285:31985-94. [PMID: 20682789 DOI: 10.1074/jbc.m110.123612] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Osterix, a zinc finger transcription factor, is specifically expressed in osteoblasts and osteocytes of all developing bones. Because no bone formation occurs in Osx-null mice, Osterix is thought to be an essential regulator of osteoblast differentiation. We report that, in several mesenchymal and osteoblastic cell types, BMP-2 induces an increase in expression of the two isoforms of Osterix arising from two alternative promoters. We identified a consensus Sp1 sequence (GGGCGG) as Osterix binding regions in the fibromodulin and the bone sialoprotein promoters in vitro and in vivo. Furthermore, we show that Osterix is a novel substrate for p38 MAPK in vitro and in vivo and that Ser-73 and Ser-77 are the regulatory sites phosphorylated by p38. Our data also demonstrate that Osterix is able to increase recruitment of p300 and Brg1 to the promoters of its target genes fibromodulin and bone sialoprotein in vivo and that it directly associates with these cofactors through protein-protein interactions. Phosphorylation of Osterix at Ser-73/77 increased its ability to recruit p300 and SWI/SNF to either fibromodulin or bone sialoprotein promoters. We therefore propose that Osterix binds to Sp1 sequences on target gene promoters and that its phosphorylation by p38 enhances recruitment of coactivators to form transcriptionally active complexes.
Collapse
Affiliation(s)
- María José Ortuño
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), E-08907 L'Hospitalet de Llobregat, Spain
| | | | | | | | | | | | | |
Collapse
|