1
|
Llano E, Todeschini AL, Felipe-Medina N, Corte-Torres MD, Condezo YB, Sanchez-Martin M, López-Tamargo S, Astudillo A, Puente XS, Pendas AM, Veitia RA. The Oncogenic FOXL2 C134W Mutation Is a Key Driver of Granulosa Cell Tumors. Cancer Res 2023; 83:239-250. [PMID: 36409821 DOI: 10.1158/0008-5472.can-22-1880] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 10/24/2022] [Accepted: 11/15/2022] [Indexed: 11/22/2022]
Abstract
Adult-type granulosa cell tumors (AGCT) are the most common type of malignant ovarian sex cord-stromal tumors. Most AGCTs carry the somatic variant c.402C>G (p.C134W) affecting the transcription factor FOXL2. Germline dominant variants in FOXL2 are responsible for blepharophimosis syndrome, which is characterized by underdevelopment of the eyelid. In this work, we generated a mouse model harboring the C134W variant of FOXL2 to evaluate in vivo the poorly understood oncogenic role of FOXL2. The mutation was dominant regarding eyelid hypoplasia, reminiscent of blepharophimosis syndrome. Interestingly, Foxl2+/C134W female mice had reduced fertility and developed AGCTs through a progression from abnormal ovaries with aberrant granulosa cells to ovaries with stromal hyperplasia and atypia and on to tumors in adut mice. The genes dysregulated in mouse AGCTs exhibited the hallmarks of cancer and were consistent with a gain-of-function of the mutated allele affecting TGFβ signaling. A comparison of these data with previous results on human AGCTs indicated similar deregulated pathways. Finally, a mutational analysis of mouse AGCT transcriptomic data suggested the absence of additional driver mutations apart from FOXL2-C134W. These results provide a clear in vivo example in which a single mutational hit triggers tumor development associated with profound transcriptomic alterations. SIGNIFICANCE A newly generated mouse model carrying a FOXL2 mutation characteristic of adult-type granulosa cell tumors shows that FOXL2 C134W shifts the transcriptome towards a signature of granulosa cell cancer and drives tumorigenesis.
Collapse
Affiliation(s)
- Elena Llano
- Molecular Mechanisms Program, Centro de Investigación del Cáncer and Instituto de Biologıía Molecular y Celular del Cáncer (CSIC-Universidad de Salamanca), Salamanca, Spain.,Departamento de Fisiología, Universidad de Salamanca, Salamanca, Spain
| | | | - Natalia Felipe-Medina
- Molecular Mechanisms Program, Centro de Investigación del Cáncer and Instituto de Biologıía Molecular y Celular del Cáncer (CSIC-Universidad de Salamanca), Salamanca, Spain
| | - María D Corte-Torres
- Instituto de Investigación Sanitaria de Asturias, Hospital Universitario del Principado de Asturias, Oviedo, Spain
| | - Yazmine B Condezo
- Molecular Mechanisms Program, Centro de Investigación del Cáncer and Instituto de Biologıía Molecular y Celular del Cáncer (CSIC-Universidad de Salamanca), Salamanca, Spain
| | | | - Sara López-Tamargo
- Departamento de Bioquímica y Biología Molecular, Instituto Universitario de Oncología (IUOPA), Universidad de Oviedo, Oviedo, Spain
| | - Aurora Astudillo
- Instituto de Investigación Sanitaria de Asturias, Hospital Universitario del Principado de Asturias, Oviedo, Spain
| | - Xose S Puente
- Departamento de Bioquímica, Universidad de Oviedo, Oviedo, Spain.,Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Madrid, Spain
| | - Alberto M Pendas
- Molecular Mechanisms Program, Centro de Investigación del Cáncer and Instituto de Biologıía Molecular y Celular del Cáncer (CSIC-Universidad de Salamanca), Salamanca, Spain
| | - Reiner A Veitia
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France.,Université Paris Saclay, Paris, France.,Institut de Biologie François Jacob, CEA, Fontenay-aux-Roses, Paris, France
| |
Collapse
|
2
|
DiNicolantonio JJ, McCarty MF, Barroso-Aranda J, Assanga S, Lujan LML, O'Keefe JH. A nutraceutical strategy for downregulating TGFβ signalling: prospects for prevention of fibrotic disorders, including post-COVID-19 pulmonary fibrosis. Open Heart 2021; 8:openhrt-2021-001663. [PMID: 33879509 PMCID: PMC8061562 DOI: 10.1136/openhrt-2021-001663] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/30/2021] [Indexed: 12/14/2022] Open
Affiliation(s)
- James J DiNicolantonio
- Preventive Cardiology, Saint Luke's Mid America Heart Institute, Kansas City, Missouri, USA
| | | | | | - Simon Assanga
- Department of Research and Postgraduate Studies in Food, University of Sonora, Sonora, Mexico
| | | | - James H O'Keefe
- University of Missouri-Kansas City, Saint Lukes Mid America Heart Institute, Kansas City, Missouri, USA
| |
Collapse
|
3
|
Mohandas N, Bass-Stringer S, Maksimovic J, Crompton K, Loke YJ, Walstab J, Reid SM, Amor DJ, Reddihough D, Craig JM. Epigenome-wide analysis in newborn blood spots from monozygotic twins discordant for cerebral palsy reveals consistent regional differences in DNA methylation. Clin Epigenetics 2018; 10:25. [PMID: 29484035 PMCID: PMC5824607 DOI: 10.1186/s13148-018-0457-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 02/12/2018] [Indexed: 12/21/2022] Open
Abstract
Background Cerebral palsy (CP) is a clinical description for a group of motor disorders that are heterogeneous with respect to causes, symptoms and severity. A diagnosis of CP cannot usually be made at birth and in some cases may be delayed until 2–3 years of age. This limits opportunities for early intervention that could otherwise improve long-term outcomes. CP has been recorded in monozygotic twins discordant for the disorder, indicating a potential role of non-genetic factors such as intrauterine infection, hypoxia-ischaemia, haemorrhage and thrombosis. The aim of this exploratory study was to utilise the discordant monozygotic twin model to understand and measure epigenetic changes associated with the development of CP. Methods We performed a genome-wide analysis of DNA methylation using the Illumina Infinium Human Methylation 450 BeadChip array with DNA from newborn blood spots of 15 monozygotic twin pairs who later became discordant for CP. Quality control and data preprocessing were undertaken using the minfi R package. Differential methylation analysis was performed using the remove unwanted variation (RUVm) method, taking twin pairing into account in order to identify CP-specific differentially methylated probes (DMPs), and bumphunter was performed to identify differentially methylated regions (DMRs). Results We identified 33 top-ranked DMPs based on a nominal p value cut-off of p < 1 × 10−4 and two DMRs (p < 1 × 10−3) associated with CP. The top-ranked probes related to 25 genes including HNRNPL, RASSF5, CD3D and KALRN involved in immune signalling pathways, in addition to TBC1D24, FBXO9 and VIPR2 previously linked to epileptic encephalopathy. Gene ontology and pathway analysis of top-ranked DMP-associated genes revealed enrichment of inflammatory signalling pathways, regulation of cytokine secretion and regulation of leukocyte-mediated immunity. We also identified two top-ranked DMRs including one on chromosome 6 within the promoter region of LTA gene encoding tumour necrosis factor-beta (TNF-β), an important regulator of inflammation and brain development. The second was within the transcription start site of the LIME1 gene, which plays a key role in inflammatory pathways such as MAPK signalling. CP-specific differential DNA methylation within one of our two top DMRs was validated using an independent platform, MassArray EpiTyper. Conclusions Ours is the first epigenome-wide association study of CP in disease-discordant monozygotic twin pairs and suggests a potential role for immune dysfunction in this condition. Electronic supplementary material The online version of this article (10.1186/s13148-018-0457-4) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Namitha Mohandas
- Environmental and Genetic Epidemiology Research, Murdoch Children's Research Institute, Royal Children's Hospital, Flemington Road, Parkville, Victoria 3052 Australia.,2Department of Paediatrics, The University of Melbourne, Flemington Road, Parkville, Victoria 3052 Australia
| | - Sebastian Bass-Stringer
- Environmental and Genetic Epidemiology Research, Murdoch Children's Research Institute, Royal Children's Hospital, Flemington Road, Parkville, Victoria 3052 Australia
| | - Jovana Maksimovic
- 2Department of Paediatrics, The University of Melbourne, Flemington Road, Parkville, Victoria 3052 Australia.,Bioinformatics Group, Murdoch Children's Research Institute, Royal Children's Hospital, Flemington Road, Parkville, Victoria 3052 Australia
| | - Kylie Crompton
- 2Department of Paediatrics, The University of Melbourne, Flemington Road, Parkville, Victoria 3052 Australia.,4Developmental Disability and Rehabilitation Research, Murdoch Children's Research Institute, Flemington Road, Parkville, Victoria 3052 Australia.,5Neurodevelopment and Disability, The Royal Children's Hospital, Flemington Road, Parkville, Victoria 3052 Australia
| | - Yuk J Loke
- Environmental and Genetic Epidemiology Research, Murdoch Children's Research Institute, Royal Children's Hospital, Flemington Road, Parkville, Victoria 3052 Australia
| | - Janet Walstab
- 2Department of Paediatrics, The University of Melbourne, Flemington Road, Parkville, Victoria 3052 Australia.,4Developmental Disability and Rehabilitation Research, Murdoch Children's Research Institute, Flemington Road, Parkville, Victoria 3052 Australia
| | - Susan M Reid
- 2Department of Paediatrics, The University of Melbourne, Flemington Road, Parkville, Victoria 3052 Australia.,4Developmental Disability and Rehabilitation Research, Murdoch Children's Research Institute, Flemington Road, Parkville, Victoria 3052 Australia.,5Neurodevelopment and Disability, The Royal Children's Hospital, Flemington Road, Parkville, Victoria 3052 Australia
| | - David J Amor
- 2Department of Paediatrics, The University of Melbourne, Flemington Road, Parkville, Victoria 3052 Australia.,4Developmental Disability and Rehabilitation Research, Murdoch Children's Research Institute, Flemington Road, Parkville, Victoria 3052 Australia.,5Neurodevelopment and Disability, The Royal Children's Hospital, Flemington Road, Parkville, Victoria 3052 Australia
| | - Dinah Reddihough
- 2Department of Paediatrics, The University of Melbourne, Flemington Road, Parkville, Victoria 3052 Australia.,4Developmental Disability and Rehabilitation Research, Murdoch Children's Research Institute, Flemington Road, Parkville, Victoria 3052 Australia.,5Neurodevelopment and Disability, The Royal Children's Hospital, Flemington Road, Parkville, Victoria 3052 Australia
| | - Jeffrey M Craig
- Environmental and Genetic Epidemiology Research, Murdoch Children's Research Institute, Royal Children's Hospital, Flemington Road, Parkville, Victoria 3052 Australia.,2Department of Paediatrics, The University of Melbourne, Flemington Road, Parkville, Victoria 3052 Australia.,6Centre for Molecular and Medical Research, School of Medicine, Deakin University, Geelong, Victoria 3220 Australia
| |
Collapse
|
4
|
Li B, Chen P, Qu J, Shi L, Zhuang W, Fu J, Li J, Zhang X, Sun Y, Zhuang W. Activation of LTBP3 gene by a long noncoding RNA (lncRNA) MALAT1 transcript in mesenchymal stem cells from multiple myeloma. J Biol Chem 2014; 289:29365-75. [PMID: 25187517 DOI: 10.1074/jbc.m114.572693] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Long noncoding RNAs (lncRNAs) are emerging as important regulatory molecules in tumor suppressor and oncogenic pathways. However, the magnitude of the contribution of lncRNA expression to normal human tissues and cancers has not been investigated in a comprehensive manner. Here we explored the biology of the lncRNA MALAT1 and considered the potential significance in mesenchymal stem cells from myeloma patients. By using assays such as RNA interference, luciferase, chromatin immunoprecipitation, and RNA immunoprecipitation, we showed that in mesenchymal stem cells MALAT1 promoted the activation effect of the key transcription factor Sp1 on LTBP3 promoter by modulating recruitment of Sp1 to the LTBP3 gene that regulated the bioavailability of TGF-β in particular. Our data suggested that lncRNA MALAT1 directly interacted with Sp1 and LTBP3 promoter to increase expression of LTBP3 gene. The specificity and efficiency of activation were ensured by the formation of a stable complex between MALAT1 and the LTBP3 promoter, direct interaction of MALAT1 with Sp1, and recruitment of Sp1 to the promoter. In this study, we showed that the mechanism of transcriptional activation of LTBP3 promoter depended on MALAT1 initiated from neighboring gene LTBP3 and involved both the direct interaction of the Sp1 and promoter-specific activation. Our knowledge of the role of MALAT1 in cellular transformation is pointing toward its potential use as a biomarker and a target for novel therapeutic approaches in multiple myeloma.
Collapse
Affiliation(s)
- Bingzong Li
- From the Department of Haematology, the Second Affiliated Hospital of Soochow University, Suzhou 215006
| | - Ping Chen
- From the Department of Haematology, the Second Affiliated Hospital of Soochow University, Suzhou 215006
| | - Jing Qu
- the Department of Cell Biology, School of Biology and Basic of Medical Science, Soochow University, Suzhou 215123, and
| | - Lei Shi
- the Department of Cell Biology, School of Biology and Basic of Medical Science, Soochow University, Suzhou 215123, and
| | - Wenyue Zhuang
- the Department of Molecular Biology, Medical Ecsomatics College of Beihua University, Jinlin 132013, China
| | - Jinxiang Fu
- From the Department of Haematology, the Second Affiliated Hospital of Soochow University, Suzhou 215006
| | - Jun Li
- From the Department of Haematology, the Second Affiliated Hospital of Soochow University, Suzhou 215006
| | - Xiaohui Zhang
- From the Department of Haematology, the Second Affiliated Hospital of Soochow University, Suzhou 215006
| | - Yu Sun
- From the Department of Haematology, the Second Affiliated Hospital of Soochow University, Suzhou 215006
| | - Wenzhuo Zhuang
- the Department of Cell Biology, School of Biology and Basic of Medical Science, Soochow University, Suzhou 215123, and
| |
Collapse
|
5
|
Bultmann I, Conradi A, Kretschmer C, Sterner-Kock A. Latent transforming growth factor β-binding protein 4 is downregulated in esophageal cancer via promoter methylation. PLoS One 2013; 8:e65614. [PMID: 23741501 PMCID: PMC3669142 DOI: 10.1371/journal.pone.0065614] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Accepted: 04/26/2013] [Indexed: 02/07/2023] Open
Abstract
Latent transforming growth factor β-binding protein 4 (LTBP4) is an extracellular matrix molecule that is a member of important connective tissue networks and is needed for the correct folding and the secretion of TGF-β1. LTBP4 is downregulated in carcinomas of various tissues. Here we show that LTBP4 is also downregulated in adenocarcinomas and squamous cell carcinomas of the esophagus in vitro and in vivo. Re-expression of LTBP4 in esophageal cancer cell lines reduced cell migration ability, whereas cell viability and cell proliferation remained unchanged. Hypermethylation of the promoter regions of the two main human LTBP4 transcriptional forms, LTBP4L and LTBP4S, was found to be involved in LTBP4 silencing. Detailed investigations of the methylation patterns of the promoter regions of LTBP4L and LTBP4S identified GATA1, SP1, E2F4 and SMAD3 as potential transcription factors involved in LTBP4 expression. In in vitro transcription factor activity studies we discovered E2F4 as novel powerful regulator for LTBP4S expression.
Collapse
Affiliation(s)
- Insa Bultmann
- Center for Experimental Medicine, Medical Faculty, University of Cologne, Cologne, Germany
| | | | | | | |
Collapse
|
6
|
Yu H, Zhao G, Li H, Liu X, Wang S. Candesartan antagonizes pressure overload-evoked cardiac remodeling through Smad7 gene-dependent MMP-9 suppression. Gene 2012; 497:301-6. [PMID: 22326534 DOI: 10.1016/j.gene.2012.01.081] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 01/25/2012] [Accepted: 01/29/2012] [Indexed: 11/27/2022]
Abstract
The present study was designed to investigate the underlying molecular mechanism for Angiotensin II type 1 receptor blockers (ARBs) mediated cardio-protection against pressure overload-induced cardiac remodeling with a focus on Smad7. ROCK-1, Smad3 and fibronectin expressions were increased in male C57BL/6 mice underwent transverse aortic constriction (TAC) for 2weeks. Treatment with Candesartan (2mg/kg per day) could effectively downregulate Smad3 and fibronectin accompanied by upregulating of Smad7. Further data showed that Candesartan inhibited TGF-β1 signal-induced epithelial-to-mesenchymal transition (EMT) through attenuating matrix metalloproteinases (MMP-9), such effect was abolished by knocking-down Smad7. Moreover, TAC for 2weeks caused increased collagen deposition, thickness of left ventricular anterior and posterior wall at end-diastole (LVAWD and LVPWD) and LVEF% reduction, which were reversed by treatment with Candesartan, but failed after knocking-down Smad7. In addition, LV dP/dt(max) and dP/dt(min) were increased by TAC for 2weeks, and treatment with Candesartan or Nifedipine effectively depressed the high levels of dP/dt(min) induced by TAC. However, only Candesartan-mediated protective role in improving cardiac function was suppressed by tail-vein injection of Smad7 siRNA. This study uncovered a novel role for ARBs in preventing pressure overload-induced cardiac remodeling via Smad7 upregulation, which suppressed MMP-9 expression and TGF-β1 signal-mediated EMT progress.
Collapse
Affiliation(s)
- Hong Yu
- Department of Pathology, Nantong University, Jiangsu Province, China.
| | | | | | | | | |
Collapse
|
7
|
Faherty CS, Merrell DS, Semino-Mora C, Dubois A, Ramaswamy AV, Maurelli AT. Microarray analysis of Shigella flexneri-infected epithelial cells identifies host factors important for apoptosis inhibition. BMC Genomics 2010; 11:272. [PMID: 20429941 PMCID: PMC2996966 DOI: 10.1186/1471-2164-11-272] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Accepted: 04/29/2010] [Indexed: 01/05/2023] Open
Abstract
Background Shigella flexneri inhibits apoptosis in infected epithelial cells. In order to understand the pro-survival effects induced by the bacteria, we utilized apoptosis-specific microarrays to analyze the changes in eukaryotic gene expression in both infected and uninfected cells in the presence and absence of staurosporine, a chemical inducer of the intrinsic pathway of apoptosis. The goal of this research was to identify host factors that contribute to apoptosis inhibition in infected cells. Results The microarray analysis revealed distinct expression profiles in uninfected and infected cells, and these changes were altered in the presence of staurosporine. These profiles allowed us to make comparisons between the treatment groups. Compared to uninfected cells, Shigella-infected epithelial cells, both in the presence and absence of staurosporine, showed significant induced expression of JUN, several members of the inhibitor of apoptosis gene family, nuclear factor κB and related genes, genes involving tumor protein 53 and the retinoblastoma protein, and surprisingly, genes important for the inhibition of the extrinsic pathway of apoptosis. We confirmed the microarray results for a selection of genes using in situ hybridization analysis. Conclusion Infection of epithelial cells with S. flexneri induces a pro-survival state in the cell that results in apoptosis inhibition in the presence and absence of staurosporine. The bacteria may target these host factors directly while some induced genes may represent downstream effects due to the presence of the bacteria. Our results indicate that the bacteria block apoptosis at multiple checkpoints along both pathways so that even if a cell fails to prevent apoptosis at an early step, Shigella will block apoptosis at the level of caspase-3. Apoptosis inhibition is most likely vital to the survival of the bacteria in vivo. Future characterization of these host factors is required to fully understand how S. flexneri inhibits apoptosis in epithelial cells.
Collapse
Affiliation(s)
- Christina S Faherty
- Department of Microbiology and Immunology, F, Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
| | | | | | | | | | | |
Collapse
|
8
|
Kantola AK, Ryynänen MJ, Lhota F, Keski-Oja J, Koli K. Independent regulation of short and long forms of latent TGF-beta binding protein (LTBP)-4 in cultured fibroblasts and human tissues. J Cell Physiol 2010; 223:727-36. [PMID: 20175115 DOI: 10.1002/jcp.22082] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Transforming growth factor (TGF)-beta is secreted and targeted into the extracellular matrix (ECM) in association with one of the latent TGF-beta binding proteins (LTBPs). Activation of these latent complexes is an important regulatory step in TGF-beta signaling. LTBPs target the growth factor into the ECM and expose it to activating mechanisms. Disruption of LTBP-4 gene causes severe developmental abnormalities in both humans and mice. Transcripts for two N-terminally distinct LTBP-4 variants, LTBP-4S (short) and -4L (long), have been identified. In the current work, we have characterized differences in the expression, processing, and ECM targeting of these LTBP-4 variants. Heart and skeletal muscle displayed expression of both variants, while liver expressed mainly LTBP-4L and lung as well as small intestine LTBP-4S. This tissue-specific expression pattern was found to originate from control of transcription by two independent promoters. Furthermore, LTBP-4S and -4L proteins were secreted and processed differently. During secretion, LTBP-4L was complexed with TGF-beta1, whereas the majority of LTBP-4S was secreted in a free form. In addition, LTBP-4S was incorporated into the ECM, while full-length LTBP-4L was not readily detectable in the ECM. These data suggest that LTBP-4 functions are modified by tissue-specific expression of the two N-terminally distinct variants, which in addition exhibit significant differences in cellular processing and targeting, that is, this provides a basis for understanding molecular diversity in LTBP-4 structure and function.
Collapse
Affiliation(s)
- Anna K Kantola
- Department of Virology, Haartman Institute and Helsinki University Hospital, University of Helsinki, Helsinki, Finland
| | | | | | | | | |
Collapse
|
9
|
Koli K, Ryynänen MJ, Keski-Oja J. Latent TGF-beta binding proteins (LTBPs)-1 and -3 coordinate proliferation and osteogenic differentiation of human mesenchymal stem cells. Bone 2008; 43:679-88. [PMID: 18672106 DOI: 10.1016/j.bone.2008.06.016] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Revised: 05/21/2008] [Accepted: 06/29/2008] [Indexed: 02/04/2023]
Abstract
Mesenchymal stem cells (MSCs) possess the capability to differentiate into bone forming cells, osteoblasts, and thus represent a new therapeutic tool in regenerative medicine. Transforming growth factor (TGF)-beta is abundantly present in bone tissue where it regulates osteoblast and osteoclast functions in a complex manner. Latent TGF-beta binding protein (LTBP)-1 mediates the extracellular matrix (ECM) targeting and accumulation of most TGF-beta in the bone. We describe here an important regulatory role for LTBP-3 in TGF-beta activation and autocrine growth control in MSCs. LTBP-3 knockdown via siRNA mediated silencing resulted in reduced cell proliferation and reduced osteogenic differentiation. When MSCs were induced to undergo differentiation, LTBP-3 levels became downregulated in parallel with reduced TGF-beta activation. These changes coincided with the matrix maturation phase of osteogenic differentiation. The mechanism of LTBP-3 is most likely via TGF-beta activation in the early proliferative phase of the differentiation process. Later, when TGF-beta activity would inhibit further maturation and mineralization, LTBP-3 expression becomes downregulated and LTBP-1 containing large latent TGF-beta1 complexes accumulate into the ECM. These complexes represent readily available targets for osteoclast mediated release and activation of TGF-beta in bone tissue. Our results provide evidence that LTBP isoforms can differentially regulate TGF-beta activation and ECM accumulation during osteogenic differentiation.
Collapse
Affiliation(s)
- Katri Koli
- Departments of Virology and Pathology, Haartman Institute and Helsinki University Hospital, University of Helsinki, Helsinki, Finland.
| | | | | |
Collapse
|