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Zhu Y, Kang A, Kuai Y, Guo Y, Miao X, Zhu L, Kong M, Li N. The chromatin remodeling protein BRG1 regulates HSC-myofibroblast differentiation and liver fibrosis. Cell Death Dis 2023; 14:826. [PMID: 38092723 PMCID: PMC10719330 DOI: 10.1038/s41419-023-06351-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 11/21/2023] [Accepted: 11/29/2023] [Indexed: 12/17/2023]
Abstract
Excessive fibrogenic response in the liver disrupts normal hepatic anatomy and function heralding such end-stage liver diseases as hepatocellular carcinoma and cirrhosis. Myofibroblasts, derived primarily from hepatic stellate cells (HSCs), are the effector of liver fibrosis. In the present study we investigated the mechanism by which Brahma-related gene 1 (BRG1, encoded by Smarca4) regulates HSC-myofibroblast transition and the implication in intervention against liver fibrosis. We report that BRG1 expression was elevated during HSC maturation in cell culture, in animal models, and in human cirrhotic liver biopsy specimens. HSC-specific deletion of BRG1 attenuated liver fibrosis in several different animal models. In addition, BRG1 ablation in myofibroblasts ameliorated liver fibrosis. RNA-seq identified IGFBP5 as a novel target for BRG1. Over-expression of IGFBP5 partially rescued the deficiency in myofibroblast activation when BRG1 was depleted. On the contrary, IGFBP5 knockdown suppressed HSC-myofibroblast transition in vitro and mollified liver fibrosis in mice. Mechanistically, IGFBP5 interacted with Bat3 to stabilize the Bat3-TβR complex and sustain TGF-β signaling. In conclusion, our data provide compelling evidence that BRG1 is a pivotal regulator of liver fibrosis by programming HSC-myofibroblast transition.
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Affiliation(s)
- Yuwen Zhu
- Key Laboratory of Targeted Intervention of Cardiovascular Disease and Collaborative Innovation Center for Cardiovascular Translational Medicine, Departments of Pathophysiology and Human Anatomy, Nanjing Medical University, Nanjing, China
| | - Aoqi Kang
- Key Laboratory of Targeted Intervention of Cardiovascular Disease and Collaborative Innovation Center for Cardiovascular Translational Medicine, Departments of Pathophysiology and Human Anatomy, Nanjing Medical University, Nanjing, China
| | - Yameng Kuai
- Key Laboratory of Targeted Intervention of Cardiovascular Disease and Collaborative Innovation Center for Cardiovascular Translational Medicine, Departments of Pathophysiology and Human Anatomy, Nanjing Medical University, Nanjing, China
| | - Yan Guo
- College of Life Sciences and Institute of Biomedical Research, Liaocheng University, Liaocheng, China
| | - Xiulian Miao
- College of Life Sciences and Institute of Biomedical Research, Liaocheng University, Liaocheng, China
| | - Li Zhu
- Department of Hepatobiliary Surgery, The Third Affiliated Hospital of Soochow University, Changzhou, China.
| | - Ming Kong
- State Key Laboratory of Natural Medicines, Department of Pharmacology, China Pharmaceutical University, Nanjing, China.
| | - Nan Li
- Key Laboratory of Targeted Intervention of Cardiovascular Disease and Collaborative Innovation Center for Cardiovascular Translational Medicine, Departments of Pathophysiology and Human Anatomy, Nanjing Medical University, Nanjing, China.
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Baxter RC. Signaling Pathways of the Insulin-like Growth Factor Binding Proteins. Endocr Rev 2023; 44:753-778. [PMID: 36974712 PMCID: PMC10502586 DOI: 10.1210/endrev/bnad008] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 01/25/2023] [Accepted: 03/15/2023] [Indexed: 03/29/2023]
Abstract
The 6 high-affinity insulin-like growth factor binding proteins (IGFBPs) are multifunctional proteins that modulate cell signaling through multiple pathways. Their canonical function at the cellular level is to impede access of insulin-like growth factor (IGF)-1 and IGF-2 to their principal receptor IGF1R, but IGFBPs can also inhibit, or sometimes enhance, IGF1R signaling either through their own post-translational modifications, such as phosphorylation or limited proteolysis, or by their interactions with other regulatory proteins. Beyond the regulation of IGF1R activity, IGFBPs have been shown to modulate cell survival, migration, metabolism, and other functions through mechanisms that do not appear to involve the IGF-IGF1R system. This is achieved by interacting directly or functionally with integrins, transforming growth factor β family receptors, and other cell-surface proteins as well as intracellular ligands that are intermediates in a wide range of pathways. Within the nucleus, IGFBPs can regulate the diverse range of functions of class II nuclear hormone receptors and have roles in both cell senescence and DNA damage repair by the nonhomologous end-joining pathway, thus potentially modifying the efficacy of certain cancer therapeutics. They also modulate some immune functions and may have a role in autoimmune conditions such as rheumatoid arthritis. IGFBPs have been proposed as attractive therapeutic targets, but their ubiquity in the circulation and at the cellular level raises many challenges. By understanding the diversity of regulatory pathways with which IGFBPs interact, there may still be therapeutic opportunities based on modulation of IGFBP-dependent signaling.
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Affiliation(s)
- Robert C Baxter
- Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital,St Leonards, NSW 2065, Australia
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3
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Du H, Zhou Y, Du X, Zhang P, Cao Z, Sun Y. Insulin-like growth factor binding protein 5b of Trachinotus ovatus and its heparin-binding motif play a critical role in host antibacterial immune responses via NF-κB pathway. Front Immunol 2023; 14:1126843. [PMID: 36865533 PMCID: PMC9972581 DOI: 10.3389/fimmu.2023.1126843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Accepted: 01/25/2023] [Indexed: 02/16/2023] Open
Abstract
Introduction Insulin-like growth factor binding protein 5 (IGFBP5) exerts an essential biological role in many processes, including apoptosis, cellular differentiation, growth, and immune responses. However, compared to mammalians, our knowledge of IGFBP5 in teleosts remains limited. Methods In this study, TroIGFBP5b, an IGFBP5 homologue from golden pompano (Trachinotus ovatus) was identified. Quantitative real-time PCR (qRT-PCR) was used to check its mRNA expression level in healthy condition and after stimulation. In vivo overexpression and RNAi knockdown method were performed to evaluate the antibacterial profile. We constructed a mutant in which HBM was deleted to better understand the mechanism of its role in antibacterial immunity. Subcellular localization and nuclear translocation were verified by immunoblotting. Further, proliferation of head kidney lymphocytes (HKLs) and phagocytic activity of head kidney macrophages (HKMs) were detected through CCK-8 assay and flow cytometry. Immunofluorescence microscopy assay (IFA) and dual luciferase reporter (DLR) assay were used to evaluate the activity in nuclear factor-κB (NF-κβ) pathway. Results The TroIGFBP5b mRNA expression level was upregulated after bacterial stimulation. In vivo, TroIGFBP5b overexpression significantly improved the antibacterial immunity of fish. In contrast, TroIGFBP5b knockdown significantly decreased this ability. Subcellular localization results showed that TroIGFBP5b and TroIGFBP5b-δHBM were both present in the cytoplasm of GPS cells. After stimulation, TroIGFBP5b-δHBM lost the ability to transfer from the cytoplasm to the nucleus. In addition, rTroIGFBP5b promoted the proliferation of HKLs and phagocytosis of HKMs, whereas rTroIGFBP5b-δHBM, suppressed these facilitation effects. Moreover, the in vivo antibacterial ability of TroIGFBP5b was suppressed and the effects of promoting expression of proinflammatory cytokines in immune tissues were nearly lost after HBM deletion. Furthermore, TroIGFBP5b induced NF-κβ promoter activity and promoted nuclear translocation of p65, while these effects were inhibited when the HBM was deleted. Discussion Taken together, our results suggest that TroIGFBP5b plays an important role in golden pompano antibacterial immunity and activation of the NF-κβ signalling pathway, providing the first evidence that the HBM of TroIGFBP5b plays a critical role in these processes in teleosts.
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Affiliation(s)
- Hehe Du
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, China.,Hainan Provincial Key Laboratory for Tropical Hydrobiology and Biotechnology, College of Marine Science, Hainan University, Haikou, China
| | - Yongcan Zhou
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, China.,Hainan Provincial Key Laboratory for Tropical Hydrobiology and Biotechnology, College of Marine Science, Hainan University, Haikou, China.,Collaborative Innovation Center of Marine Science and Technology, Hainan University, Haikou, China
| | - Xiangyu Du
- Hainan Provincial Key Laboratory for Tropical Hydrobiology and Biotechnology, College of Marine Science, Hainan University, Haikou, China
| | - Panpan Zhang
- Hainan Provincial Key Laboratory for Tropical Hydrobiology and Biotechnology, College of Marine Science, Hainan University, Haikou, China
| | - Zhenjie Cao
- Hainan Provincial Key Laboratory for Tropical Hydrobiology and Biotechnology, College of Marine Science, Hainan University, Haikou, China
| | - Yun Sun
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, China.,Hainan Provincial Key Laboratory for Tropical Hydrobiology and Biotechnology, College of Marine Science, Hainan University, Haikou, China.,Collaborative Innovation Center of Marine Science and Technology, Hainan University, Haikou, China
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4
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Sun Y, Xiao Z, Chen Y, Xu D, Chen S. Susceptibility Modules and Genes in Hypertrophic Cardiomyopathy by WGCNA and ceRNA Network Analysis. Front Cell Dev Biol 2022; 9:822465. [PMID: 35178407 PMCID: PMC8844202 DOI: 10.3389/fcell.2021.822465] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 12/28/2021] [Indexed: 02/05/2023] Open
Abstract
Background: We attempted to identify a regulatory competing endogenous RNA (ceRNA) network and a hub gene of Hypertrophic Cardiomyopathy (HCM). Methods: Microarray datasets of HCM tissue were obtained from NCBI Gene Expression Omnibus (GEO) database. The R package "limma" was used to identify differentially expressed genes. Online search databases were utilized to match the relation among differentially expressed long non-coding RNAs (lncRNAs), microRNAs (miRNAs) and mRNAs. Weighted correlation network analysis (WGCNA) was used to identify the correlations between key modules and HCM. STRING database was applied to construct PPI networks. Gene Set Enrichment Analysis (GSEA) was used to perform functional annotations and verified the hub genes. Results: A total of 269 DE-lncRNAs, 63 DE-miRNAs and 879 DE-mRNAs were identified in myocardial tissues from microarray datasets GSE130036, GSE36946 and GSE36961, respectively. According to online databases, we found 1 upregulated miRNA hsa-miR-184 that was targeted by 2 downregulated lncRNAs (SNHG9, AC010980.2), potentially targeted 2 downregulated mRNAs (LRRC8A, SLC7A5). 3 downregulated miRNAs (hsa-miR-17-5p, hsa-miR-876-3p, hsa-miR-139-5p) that were targeted by 9 upregulated lncRNAs, potentially targeted 21 upregulated mRNAs. Black and blue modules significantly related to HCM were identified by WGCNA. Hub gene IGFBP5 regulated by hsa-miR-17-5p, AC007389.5, AC104667.1, and AC002511.2 was identified. GSEA indicated that IGFBP5 might involve in the synthesis of myosin complex, participate in kinesin binding, motor activity and function via the regulation of actin cytoskeleton. Conclusion: The results provide a potential molecular regulatory mechanism for the diagnosis and treatment of HCM. IGFBP5 might play an important role in the progression of HCM.
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Affiliation(s)
- Yifan Sun
- Department of Cardiology, First Affiliated Hospital of Shantou University Medical College, Shantou, China
| | - Zhongbo Xiao
- Department of Cardiology, First Affiliated Hospital of Shantou University Medical College, Shantou, China
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5
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Dittmer J. Biological effects and regulation of IGFBP5 in breast cancer. Front Endocrinol (Lausanne) 2022; 13:983793. [PMID: 36093095 PMCID: PMC9453429 DOI: 10.3389/fendo.2022.983793] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 08/08/2022] [Indexed: 11/13/2022] Open
Abstract
The insulin-like growth factor receptor (IGF1R) pathway plays an important role in cancer progression. In breast cancer, the IGF1R pathway is linked to estrogen-dependent signaling. Regulation of IGF1R activity is complex and involves the actions of its ligands IGF1 and IGF2 and those of IGF-binding proteins (IGFBPs). Six IGFBPs are known that share the ability to form complexes with the IGFs, by which they control the bioavailability of these ligands. Besides, each of the IGFBPs have specific features. In this review, the focus lies on the biological effects and regulation of IGFBP5 in breast cancer. In breast cancer, estrogen is a critical regulator of IGFBP5 transcription. It exerts its effect through an intergenic enhancer loop that is part of the chromosomal breast cancer susceptibility region 2q35. The biological effects of IGFBP5 depend upon the cellular context. By inhibiting or promoting IGF1R signaling, IGFBP5 can either act as a tumor suppressor or promoter. Additionally, IGFBP5 possesses IGF-independent activities, which contribute to the complexity by which IGFBP5 interferes with cancer cell behavior.
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6
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Tintut Y, Demer LL. Potential impact of the steroid hormone, vitamin D, on the vasculature. Am Heart J 2021; 239:147-153. [PMID: 34051171 DOI: 10.1016/j.ahj.2021.05.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 05/20/2021] [Indexed: 02/06/2023]
Abstract
The role of vitamin D in the cardiovascular system is complex because it regulates expression of genes involved in diverse metabolic processes. Although referred to as a vitamin, it is more accurately considered a steroid hormone, because it is produced endogenously in the presence of ultraviolet light. It occurs as a series of sequentially activated forms, here referred to as vitamin D-hormones. A little-known phenomenon, based on pre-clinical data, is that its biodistribution and potential effects on vascular disease likely depend on whether it is derived from diet or sunlight. Diet-derived vitamin D-hormones are carried in the blood, at least in part, in chylomicrons and lipoprotein particles, including low-density lipoprotein. Since low-density lipoprotein is known to accumulate in the artery wall and atherosclerotic plaque, diet-derived vitamin D-hormones may also collect there, and possibly promote the osteochondrogenic mineralization associated with plaque. Also, little known is the fact that the body stores vitamin D-hormones in adipose tissue with a half-life on the order of months, raising doubts about whether the use of the term "daily requirement" is appropriate. Cardiovascular effects of vitamin D-hormones are controversial, and risk appears to increase with both low and high blood levels. Since low serum vitamin D-hormone concentration is reportedly associated with increased cardiovascular and orthopedic risk, oral supplementation is widely used, often together with calcium supplements. However, meta-analyses show that oral vitamin D-hormone supplementation does not protect against cardiovascular events, findings that are also supported by a randomized controlled trial. These considerations suggest that prevalent recommendations for vitamin D-hormone supplementation for the purpose of cardiovascular protection should be carefully reconsidered.
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Affiliation(s)
- Yin Tintut
- Department of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA; Department of Physiology, University of California, Los Angeles (UCLA), Los Angeles, CA; Department of Orthopaedic Surgery, University of California, Los Angeles (UCLA), Los Angeles, CA
| | - Linda L Demer
- Department of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA; Department of Physiology, University of California, Los Angeles (UCLA), Los Angeles, CA; Department of Bioengineering, University of California, Los Angeles (UCLA), Los Angeles, CA; VA Greater Los Angeles Healthcare System, Los Angeles, Los Angeles, CA.
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7
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Bollen SE, Atherton PJ. Myogenic, genomic and non-genomic influences of the vitamin D axis in skeletal muscle. Cell Biochem Funct 2020; 39:48-59. [PMID: 33037688 DOI: 10.1002/cbf.3595] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 09/21/2020] [Accepted: 09/27/2020] [Indexed: 12/14/2022]
Abstract
Despite vitamin D-deficiency clinically presenting with myopathy, muscle weakness and atrophy, the mechanisms by which vitamin D exerts its homeostatic effects upon skeletal muscle remain to be fully established. Recent studies have shown that the receptor by which 1α,25-dihydroxyvitamin D3 (1,25[OH]2 D3 ) exerts its biological actions (ie, the vitamin D receptor, VDR) elicits both genomic and non-genomic effects upon skeletal muscle. The controversy surrounding skeletal muscle VDR mRNA/protein expression in post-natal muscle has been allayed by myriad recent studies, while dynamic expression of VDR throughout myogenesis, and association of higher VDR levels during muscle regeneration/immature muscle cells, suggests a role in myogenesis and perhaps an enrichment of VDR in satellite cells. Accordingly, in vitro studies have demonstrated 1,25(OH)2 D3 is anti-proliferative in myoblasts, yet pro-differentiation in latter stages of myogenesis. These effects involve modulation of gene expression (VDR as a transcriptional co-activator controls ~3% of the genome) and post-genomic intracellular signalling for example, via c-Src and alterations to intramuscular calcium homeostasis and proteostasis. The aim of this review is to consider the biomolecular role for the vitamin D/VDR axis in myogenesis, while also exploring global evidence for genomic and non-genomic mechanisms of action for 1,25(OH)2 D3 /VDR.
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Affiliation(s)
- Shelby E Bollen
- MRC/ARUK Centre for Musculoskeletal Ageing Research and National Institute for Health Research (NIHR), Nottingham Biomedical Research Centre (BRC), School of Medicine, University of Nottingham, Derby, UK
| | - Philip J Atherton
- MRC/ARUK Centre for Musculoskeletal Ageing Research and National Institute for Health Research (NIHR), Nottingham Biomedical Research Centre (BRC), School of Medicine, University of Nottingham, Derby, UK
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8
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Poreba E, Durzynska J. Nuclear localization and actions of the insulin-like growth factor 1 (IGF-1) system components: Transcriptional regulation and DNA damage response. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2020; 784:108307. [PMID: 32430099 DOI: 10.1016/j.mrrev.2020.108307] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 02/25/2020] [Accepted: 02/26/2020] [Indexed: 12/14/2022]
Abstract
Insulin-like growth factor (IGF) system stimulates growth, proliferation, and regulates differentiation of cells in a tissue-specific manner. It is composed of two insulin-like growth factors (IGF-1 and IGF-2), six insulin-like growth factor-binding proteins (IGFBPs), and two insulin-like growth factor receptors (IGF-1R and IGF-2R). IGF actions take place mostly through the activation of the plasma membrane-bound IGF-Rs by the circulating ligands (IGFs) released from the IGFBPs that stabilize their levels in the serum. This review focuses on the IGF-1 part of the system. The IGF-1 gene, which is expressed mainly in the liver as well as in other tissues, comprises six alternatively spliced exons that code for three protein isoforms (pro-IGF-1A, pro-IGF-1B, and pro-IGF-1C), which are processed to mature IGF-1 and E-peptides. The IGF-1R undergoes autophosphorylation, resulting in a signaling cascade involving numerous cytoplasmic proteins such as AKT and MAPKs, which regulate the expression of target genes. However, a more complex picture of the axis has recently emerged with all its components being translocated to the nuclear compartment. IGF-1R takes part in the regulation of gene expression by forming transcription complexes, modifying the activity of chromatin remodeling proteins, and participating in DNA damage tolerance mechanisms. Four IGFBPs contain a nuclear localization signal (NLS), which targets them to the nucleus, where they regulate gene expression (IGFBP-2, IGFBP-3, IGFBP-5, IGFBP-6) and DNA damage repair (IGFBP-3 and IGFBP-6). Last but not least, the IGF-1B isoform has been reported to be localized in the nuclear compartment. However, no specific molecular actions have been assigned to the nuclear pro-IGF-1B or its derivative EB peptide. Therefore, further studies are needed to shed light on their nuclear activity. These recently uncovered nuclear actions of different components of the IGF-1 axis are relevant in cancer cell biology and are discussed in this review.
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Affiliation(s)
- Elzbieta Poreba
- Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, ul. Uniwersytetu Poznańskiego 6, 61-614, Poznań, Poland.
| | - Julia Durzynska
- Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, ul. Uniwersytetu Poznańskiego 6, 61-614, Poznań, Poland.
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9
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Duan C, Allard JB. Insulin-Like Growth Factor Binding Protein-5 in Physiology and Disease. Front Endocrinol (Lausanne) 2020; 11:100. [PMID: 32194505 PMCID: PMC7063065 DOI: 10.3389/fendo.2020.00100] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 02/17/2020] [Indexed: 12/25/2022] Open
Abstract
Insulin-like growth factor (IGF) signaling is regulated by a conserved family of IGF binding proteins (IGFBPs) in vertebrates. Among the six distinct types of IGFBPs, IGFBP-5 is the most highly conserved across species and has the broadest range of biological activities. IGFBP-5 is expressed in diverse cell types, and its expression level is regulated by a variety of signaling pathways in different contexts. IGFBP-5 can exert a range of biological actions including prolonging the half-life of IGFs in the circulation, inhibition of IGF signaling by competing with the IGF-1 receptor for ligand binding, concentrating IGFs in certain cells and tissues, and potentiation of IGF signaling by delivery of IGFs to the IGF-1 receptor. IGFBP-5 also has IGF-independent activities and is even detected in the nucleus. Its broad biological activities make IGFBP-5 an excellent representative for understanding IGFBP functions. Despite its evolutionary conservation and numerous biological activities, knockout of IGFBP-5 in mice produced only a negligible phenotype. Recent research has begun to explain this paradox by demonstrating cell type-specific and physiological/pathological context-dependent roles for IGFBP-5. In this review, we survey and discuss what is currently known about IGFBP-5 in normal physiology and human disease. Based on recent in vivo genetic evidence, we suggest that IGFBP-5 is a multifunctional protein with the ability to act as a molecular switch to conditionally regulate IGF signaling.
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10
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Abstract
Understanding of vitamin D physiology is important because about half of the population is being diagnosed with deficiency and treated with supplements. Clinical guidelines were developed based on observational studies showing an association between low serum levels and increased cardiovascular risk. However, new randomized controlled trials have failed to confirm any cardiovascular benefit from supplementation in the general population. A major concern is that excess vitamin D is known to cause calcific vasculopathy and valvulopathy in animal models. For decades, administration of vitamin D has been used in rodents as a reliable experimental model of vascular calcification. Technically, vitamin D is a misnomer. It is not a true vitamin because it can be synthesized endogenously through ultraviolet exposure of the skin. It is a steroid hormone that comes in 3 forms that are sequential metabolites produced by hydroxylases. As a fat-soluble hormone, the vitamin D-hormone metabolites must have special mechanisms for delivery in the aqueous bloodstream. Importantly, endogenously synthesized forms are carried by a binding protein, whereas dietary forms are carried within lipoprotein particles. This may result in distinct biodistributions for sunlight-derived versus supplement-derived vitamin D hormones. Because the cardiovascular effects of vitamin D hormones are not straightforward, both toxic and beneficial effects may result from current recommendations.
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Affiliation(s)
- Linda L Demer
- From the Departments of Medicine (L.L.D., J.J.H., Y.T.) .,Physiology (L.L.D., Y.T.).,Bioengineering (L.L.D.)
| | - Jeffrey J Hsu
- From the Departments of Medicine (L.L.D., J.J.H., Y.T.)
| | - Yin Tintut
- From the Departments of Medicine (L.L.D., J.J.H., Y.T.).,Physiology (L.L.D., Y.T.).,Orthopaedic Surgery (Y.T.), University of California, Los Angeles
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11
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Liso A, Capitanio N, Gerli R, Conese M. From fever to immunity: A new role for IGFBP-6? J Cell Mol Med 2018; 22:4588-4596. [PMID: 30117676 PMCID: PMC6156343 DOI: 10.1111/jcmm.13738] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 05/22/2018] [Indexed: 12/12/2022] Open
Abstract
Fever is a fundamental response to infection and a hallmark of inflammatory disease, which has been conserved and shaped through millions of years of natural selection. Although fever is able to stimulate both innate and adaptive immune responses, the very nature of all the molecular thermosensors, the timing and the detailed mechanisms translating a physical trigger into a fundamental biological response are incompletely understood. Here we discuss the consequence of hyperthermic stress in dendritic cells (DCs), and how the sole physical input is sensed as an alert stimulus triggering a complex transition in a very narrow temporal window. Importantly, we review recent findings demonstrating the significant and specific changes discovered in gene expression and in the metabolic phenotype associated with hyperthermia in DCs. Furthermore, we discuss the results that support a model based on a thermally induced autocrine signalling, which rewires and sets a metabolism checkpoint linked to immune activation of dendritic cells. Importantly, in this context, we highlight the novel regulatory functions discovered for IGFBP‐6 protein: induction of chemotaxis; capacity to increase oxidative burst and degranulation of neutrophils, ability to induce metabolic changes in DCs. Finally, we discuss the role of IGFBP‐6 in autoimmune disease and how novel mechanistic insights could lead to exploit thermal stress‐related mechanisms in the context of cancer therapy.
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Affiliation(s)
- Arcangelo Liso
- Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Nazzareno Capitanio
- Department of Clinical and Experimental Medicine, University of Foggia, Foggia, Italy
| | - Roberto Gerli
- Department of Medicine, University of Perugia, Perugia, Italy
| | - Massimo Conese
- Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
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12
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Abstract
Insulin-like growth factor-binding proteins (IGFBPs) 1-6 bind IGFs but not insulin with high affinity. They were initially identified as serum carriers and passive inhibitors of IGF actions. However, subsequent studies showed that, although IGFBPs inhibit IGF actions in many circumstances, they may also potentiate these actions. IGFBPs are widely expressed in most tissues, and they are flexible endocrine and autocrine/paracrine regulators of IGF activity, which is essential for this important physiological system. More recently, individual IGFBPs have been shown to have IGF-independent actions. Mechanisms underlying these actions include (i) interaction with non-IGF proteins in compartments including the extracellular space and matrix, the cell surface and intracellular space, (ii) interaction with and modulation of other growth factor pathways including EGF, TGF-β and VEGF, and (iii) direct or indirect transcriptional effects following nuclear entry of IGFBPs. Through these IGF-dependent and IGF-independent actions, IGFBPs modulate essential cellular processes including proliferation, survival, migration, senescence, autophagy and angiogenesis. They have been implicated in a range of disorders including malignant, metabolic, neurological and immune diseases. A more complete understanding of their cellular roles may lead to the development of novel IGFBP-based therapeutic opportunities.
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Affiliation(s)
- L A Bach
- Department of Medicine (Alfred)Monash University, Melbourne, Australia
- Department of Endocrinology and DiabetesAlfred Hospital, Melbourne, Australia
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13
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Clemmons DR. Role of IGF-binding proteins in regulating IGF responses to changes in metabolism. J Mol Endocrinol 2018; 61:T139-T169. [PMID: 29563157 DOI: 10.1530/jme-18-0016] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 03/21/2018] [Indexed: 12/22/2022]
Abstract
The IGF-binding protein family contains six members that share significant structural homology. Their principal function is to regulate the actions of IGF1 and IGF2. These proteins are present in plasma and extracellular fluids and regulate access of both IGF1 and II to the type I IGF receptor. Additionally, they have functions that are independent of their ability to bind IGFs. Each protein is regulated independently of IGF1 and IGF2, and this provides an important mechanism by which other hormones and physiologic variables can regulate IGF actions indirectly. Several members of the family are sensitive to changes in intermediary metabolism. Specifically the presence of obesity/insulin resistance can significantly alter the expression of these proteins. Similarly changes in nutrition or catabolism can alter their synthesis and degradation. Multiple hormones such as glucocorticoids, androgens, estrogen and insulin regulate IGFBP synthesis and bioavailability. In addition to their ability to regulate IGF access to receptors these proteins can bind to distinct cell surface proteins or proteins in extracellular matrix and several cellular functions are influenced by these interactions. IGFBPs can be transported intracellularly and interact with nuclear proteins to alter cellular physiology. In pathophysiologic states, there is significant dysregulation between the changes in IGFBP synthesis and bioavailability and changes in IGF1 and IGF2. These discordant changes can lead to marked alterations in IGF action. Although binding protein physiology and pathophysiology are complex, experimental results have provided an important avenue for understanding how IGF actions are regulated in a variety of physiologic and pathophysiologic conditions.
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Affiliation(s)
- David R Clemmons
- Department of MedicineUNC School of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
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Abstract
Cancer stem cells (CSCs) represent the root of many solid tumors including ovarian cancer. Eradication of CSCs represents a novel cancer therapeutic strategy. Calcitriol, also known as 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], is an active metabolite of vitamin D, functioning as a potent steroid hormone. Calcitriol has shown anti-tumor effects in various cancers by regulating multiple signaling pathways. It has been reported that calcitriol can regulate the properties of normal and CSCs. However, the effect of calcitriol on the ovarian cancer growth and ovarian CSCs is still unclear. Here, by using a mouse subcutaneous xenograft model generated with human ovarian cancer cells, we have demonstrated that administration of calcitriol is able to strikingly delay the tumor growth. Calcitriol treatment can also deplete the ovarian CSC population characterized by ALDH+ and CD44+CD117+; decrease their capacity to form sphere under the CSC culture condition, and reduce the frequency of tumor-initiating cells, as evaluated by in vivo limiting dilution analysis. Mechanistic investigation revealed that calcitriol depletes CSCs via the nuclear vitamin D receptor (VDR)-mediated inhibition of the Wnt pathway. Furthermore, the activation of VDR pathway is more sensitive to calcitriol in ovarian CSCs than in non-CSCs, although the expression levels of VDR are comparable. Taken together, our data indicate that calcitriol is able to deplete the ovarian CSC population by inhibiting their Wnt signaling pathway, consequently, impeding the growth of xenograft tumors.
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15
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Sun M, Long J, Yi Y, Xia W. Importin α-importin β complex mediated nuclear translocation of insulin-like growth factor binding protein-5. Endocr J 2017; 64:963-975. [PMID: 28835592 DOI: 10.1507/endocrj.ej17-0156] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Insulin-like growth factor-binding protein (IGFBP)-5 is a secreted protein that binds to IGFs and modulates IGF actions, as well as regulates cell proliferation, migration, and apoptosis independent of IGF. Proper cellular localization is critical for the effective function of most signaling molecules. In previous studies, we have shown that the nuclear IGFBP-5 comes from ER-cytosol retro-translocation. In this study, we further investigated the pathway mediating IGFBP-5 nuclear import after it retro-translocation. Importin-α5 was identified as an IGFBP-5-interacting protein with a yeast two-hybrid system, and its interaction with IGFBP-5 was further confirmed by GST pull down and co-immunoprecipitation. Binding affinity of IGFBP-5 and importins were determined by surface plasmon resonance (IGFBP-5/importin-β: KD=2.44e-7, IGFBP-5/importin-α5: KD=3.4e-7). Blocking the importin-α5/importin-β nuclear import pathway using SiRNA or dominant negative impotin-β dramatically inhibited IGFBP-5-EGFP nuclear import, though importin-α5 overexpress does not affect IGFBP-5 nuclear import. Furthermore, nuclear IGFBP-5 was quantified using luciferase report assay. When deleted the IGFBP-5 nuclear localization sequence (NLS), IGFBP-5ΔNLS loss the ability to translocate into the nucleus and accumulation of IGFBP-5ΔNLS was visualized in the cytosol. Altogether, our findings provide a substantially evidence showed that the IGFBP-5 nuclear import is mediated by importin-α/importin-β complex, and NLS is critical domain in IGFBP-5 nuclear translocation.
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Affiliation(s)
- Min Sun
- Department of Dermatology, Xiangya Hospital, Central South University, Changsha, China
| | - Juan Long
- Department of Dermatology, Xiangya Hospital, Central South University, Changsha, China
| | - Yuxin Yi
- Department of Dermatology, Xiangya Hospital, Central South University, Changsha, China
| | - Wei Xia
- Department of Dermatology, University of Michigan, Ann Arbor, MI, USA
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16
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The Wilms tumor protein WT1 stimulates transcription of the gene encoding insulin-like growth factor binding protein 5 (IGFBP5). Gene 2017; 619:21-29. [DOI: 10.1016/j.gene.2017.03.037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 03/02/2017] [Accepted: 03/25/2017] [Indexed: 11/24/2022]
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17
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Piszczatowski RT, Lents NH. Regulation of the CCN genes by vitamin D: A possible adjuvant therapy in the treatment of cancer and fibrosis. Cell Signal 2016; 28:1604-13. [PMID: 27460560 DOI: 10.1016/j.cellsig.2016.07.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 07/18/2016] [Accepted: 07/19/2016] [Indexed: 01/21/2023]
Abstract
The CCN family is composed of six cysteine-rich, modular, and conserved proteins whose functions span a variety of tissues and include cell proliferation, adhesion, angiogenesis, and wound healing. Roles for the CCN proteins throughout the entire body including the skin, kidney, brain, blood vessels, hematopoietic compartment and others, are continuously being elucidated. Likewise, an understanding of the regulation of this important gene family is constantly becoming clearer, through identification of transcription factors that directly activate, repress, or respond to upstream cell signaling pathways, as well as other forms of gene expression control. Vitamin D (1,25-dihydroxyvitamin D3 or calcitriol), a vitamin essential for numerous biological processes, acts as a potent gene expression modulator. The regulation of the CCN gene family members by calcitriol has been described in many contexts. Here, we provide a concise and thorough overview of what is known about calcitriol and its regulation of the CCN genes, and argue that its regulation is of physiological importance in a wide breadth of tissues in which CCN genes function. In addition, we highlight the effects of vitamin D on CCN gene expression in the setting of two common pathologic conditions, fibrosis and cancer, and propose that the therapeutic effects of vitamin D3 described in these disease states may in part be attributable to CCN gene modulation. As vitamin D is perfectly safe in a wide range of doses and already showing promise as an adjuvant therapeutic agent, a deeper understanding of its control of CCN gene expression may have profound implications in clinical management of disease.
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Affiliation(s)
| | - Nathan H Lents
- Department of Sciences, John Jay College, The City University of New York, New York, NY 10019, USA.
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18
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Multiple Integrated Complementary Healing Approaches: Energetics & Light for bone. Med Hypotheses 2016; 86:18-29. [DOI: 10.1016/j.mehy.2015.10.030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 10/30/2015] [Indexed: 02/08/2023]
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19
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Baxter RC. Nuclear actions of insulin-like growth factor binding protein-3. Gene 2015; 569:7-13. [PMID: 26074086 PMCID: PMC4496269 DOI: 10.1016/j.gene.2015.06.028] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 05/27/2015] [Accepted: 06/09/2015] [Indexed: 12/11/2022]
Abstract
In addition to its actions outside the cell, cellular uptake and nuclear import of insulin-like growth factor binding protein-3 (IGFBP-3) has been recognized for almost two decades, but knowledge of its nuclear actions has been slow to emerge. IGFBP-3 has a functional nuclear localization signal and interacts with the nuclear transport protein importin-β. Within the nucleus IGFBP-3 appears to have a role in transcriptional regulation. It can bind to the nuclear receptor, retinoid X receptor-α and several of its dimerization partners, including retinoic acid receptor, vitamin D receptor (VDR), and peroxisome proliferator-activated receptor-γ (PPARγ). These interactions modulate the functions of these receptors, for example inhibiting VDR-dependent transcription in osteoblasts and PPARγ-dependent transcription in adipocytes. Nuclear IGFBP-3 can be detected by immunohistochemistry in cancer and other tissues, and its presence in the nucleus has been shown in many cell culture studies to be necessary for its pro-apoptotic effect, which may also involve interaction with the nuclear receptor Nur77, and export from the nucleus. IGFBP-3 is p53-inducible and in response to DNA damage, forms a complex with the epidermal growth factor receptor (EGFR), translocating to the nucleus to interact with DNA-dependent protein kinase. Inhibition of EGFR kinase activity or downregulation of IGFBP-3 can inhibit DNA double strand-break repair by nonhomologous end joining. IGFBP-3 thus has the ability to influence many cell functions through its interactions with intranuclear pathways, but the importance of these interactions in vivo, and their potential to be targeted for therapeutic benefit, require further investigation.
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Affiliation(s)
- Robert C Baxter
- Kolling Institute of Medical Research, University of Sydney, Level 8, Kolling Building, Royal North Shore Hospital, St Leonards, NSW 2065, Australia.
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20
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Lodhia KA, Tienchaiananda P, Haluska P. Understanding the Key to Targeting the IGF Axis in Cancer: A Biomarker Assessment. Front Oncol 2015. [PMID: 26217584 PMCID: PMC4495315 DOI: 10.3389/fonc.2015.00142] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Type 1 insulin like growth factor receptor (IGF-1R) targeted therapies showed compelling pre-clinical evidence; however, to date, this has failed to translate into patient benefit in Phase 2/3 trials in unselected patients. This was further complicated by the toxicity, including hyperglycemia, which largely results from the overlap between IGF and insulin signaling systems and associated feedback mechanisms. This has halted the clinical development of inhibitors targeting IGF signaling, which has limited the availability of biopsy samples for correlative studies to understand biomarkers of response. Indeed, a major factor contributing to lack of clinical benefit of IGF targeting agents has been difficulty in identifying patients with tumors driven by IGF signaling due to the lack of predictive biomarkers. In this review, we will describe the IGF system, rationale for targeting IGF signaling, the potential liabilities of targeting strategies, and potential biomarkers that may improve success.
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Affiliation(s)
| | | | - Paul Haluska
- Department of Oncology, Mayo Clinic , Rochester, MN , USA
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21
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IGFBP-2: The dark horse in metabolism and cancer. Cytokine Growth Factor Rev 2015; 26:329-46. [DOI: 10.1016/j.cytogfr.2014.12.001] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 12/09/2014] [Indexed: 12/29/2022]
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22
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Pon CK, Firth SM, Baxter RC. Involvement of insulin-like growth factor binding protein-3 in peroxisome proliferator-activated receptor gamma-mediated inhibition of breast cancer cell growth. Mol Cell Endocrinol 2015; 399:354-61. [PMID: 25449421 DOI: 10.1016/j.mce.2014.10.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 10/24/2014] [Accepted: 10/28/2014] [Indexed: 12/19/2022]
Abstract
We have previously reported that insulin-like growth factor binding protein-3 (IGFBP-3), a protein with dichotomous effects on both cell proliferation and cell survival, interacts with peroxisome proliferator-activated receptor gamma (PPARγ) and inhibits adipogenic PPARγ signaling. We now show that IGFBP-3 and PPARγ interact in breast cancer cells, through amino- and carboxyl-terminal residues of IGFBP-3. IGFBP-3 and the PPARγ ligands, rosiglitazone or 15-deoxy-Δ(12,14)-prostaglandin J2, separately inhibited the proliferation of MCF-7, MDA-MB-231 and MDA-MB-468 breast cancer cells. However, growth inhibition by IGFBP-3 and PPARγ ligand combined was greater than by either alone. Two IGFBP-3 mutants with reduced PPARγ binding caused no growth inhibition when used alone and abolished the inhibitory effect of rosiglitazone when used in combination with PPARγ ligand. Cell growth inhibition by PPARγ ligands was substantially blocked by IGFBP-3 siRNA and restored by exogenous IGFBP-3. We conclude that the interaction between IGFBP-3 and PPARγ is important for the growth-inhibitory effect of PPARγ ligands in human breast cancer cells, suggesting that IGFBP-3 expression by breast tumors may regulate their sensitivity toward PPARγ ligands.
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Affiliation(s)
- Cindy K Pon
- Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, St Leonards, NSW 2065, Australia
| | - Sue M Firth
- Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, St Leonards, NSW 2065, Australia
| | - Robert C Baxter
- Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, St Leonards, NSW 2065, Australia.
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23
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Abstract
The six members of the family of insulin-like growth factor (IGF) binding proteins (IGFBPs) were originally characterized as passive reservoirs of circulating IGFs, but they are now understood to have many actions beyond their endocrine role in IGF transport. IGFBPs also function in the pericellular and intracellular compartments to regulate cell growth and survival - they interact with many proteins, in addition to their canonical ligands IGF-I and IGF-II. Intranuclear roles of IGFBPs in transcriptional regulation, induction of apoptosis and DNA damage repair point to their intimate involvement in tumour development, progression and resistance to treatment. Tissue or circulating IGFBPs might also be useful as prognostic biomarkers.
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Affiliation(s)
- Robert C Baxter
- Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, St Leonards, New South Wales 2065, Australia
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24
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Riley D, Welsh T, Gill C, Hulsman L, Herring A, Riggs P, Sawyer J, Sanders J. Whole genome association of SNP with newborn calf cannon bone length. Livest Sci 2013. [DOI: 10.1016/j.livsci.2013.05.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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25
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Baxter RC. Insulin-like growth factor binding protein-3 (IGFBP-3): Novel ligands mediate unexpected functions. J Cell Commun Signal 2013; 7:179-89. [PMID: 23700234 DOI: 10.1007/s12079-013-0203-9] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In addition to its important role in the regulation of somatic growth by acting as the major circulating transport protein for the insulin-like growth factors (IGFs), IGF binding protein-3 (IGFBP-3) has a variety of intracellular ligands that point to its function within major signaling pathways. The discovery of its interaction with the retinoid X receptor has led to the elucidation of roles in regulating the function of several nuclear hormone receptors including retinoic acid receptor-α, Nur77 and vitamin D receptor. Its interaction with the nuclear hormone receptor peroxisome proliferator-activated receptor-γ is believed to be involved in regulating adipocyte differentiation, which is also modulated by IGFBP-3 through an interaction with TGFβ/Smad signaling. IGFBP-3 can induce apoptosis alone or in conjunction with other agents, and in different systems can activate caspases -8 and -9. At least two unrelated proteins (LRP1 and TMEM219) have been designated as receptors for IGFBP-3, the latter with a demonstrated role in inducing caspase-8-dependent apoptosis. In contrast, IGFBP-3 also has demonstrated roles in survival-related functions, including the repair of DNA double-strand breaks through interaction with the epidermal growth factor receptor and DNA-dependent protein kinase, and the induction of autophagy through interaction with GRP78. The ability of IGFBP-3 to modulate the balance between pro-apoptotic and pro-survival sphingolipids by regulating sphingosine kinase 1 and sphingomyelinases may be integral to its role at the crossroads between cell death and survival in response to a variety of stimuli. The pleiotropic nature of IGFBP-3 activity supports the idea that IGFBP-3 itself, or pathways with which it interacts, should be investigated as targets of therapy for a variety of diseases.
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Affiliation(s)
- Robert C Baxter
- Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, Level 8, Kolling Building, St Leonards, NSW, 2065, Australia,
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26
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Li J, Jin D, Fu S, Mei G, Zhou J, Lei L, Yu B, Wang G. Insulin-like growth factor binding protein-3 modulates osteoblast differentiation via interaction with vitamin D receptor. Biochem Biophys Res Commun 2013; 436:632-7. [DOI: 10.1016/j.bbrc.2013.04.111] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2013] [Accepted: 04/27/2013] [Indexed: 11/16/2022]
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27
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Role of insulin-like growth factor binding protein-3 in 1, 25-dihydroxyvitamin-d 3 -induced breast cancer cell apoptosis. Int J Cell Biol 2013; 2013:960378. [PMID: 23690781 PMCID: PMC3652201 DOI: 10.1155/2013/960378] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 02/16/2013] [Accepted: 02/24/2013] [Indexed: 11/24/2022] Open
Abstract
Insulin-like growth factor I (IGF-I) is implicated in breast cancer development and 1, 25-dihydroxyvitamin D3 (1, 25-D3) has been shown to attenuate prosurvival effects of IGF-I on breast cancer cells. In this study the role of IGF binding protein-3 (IGFBP-3) in 1, 25-D3-induced apoptosis was investigated using parental MCF-7 breast cancer cells and MCF-7/VDR cells, which are resistant to the growth inhibitory effects of 1, 25-D3. Treatment with 1, 25-D3 increased IGFBP-3 mRNA expression in both cell lines but increases in intracellular IGFBP-3 protein and its secretion were observed only in MCF-7. 1, 25-D3-induced apoptosis was not associated with activation of any caspase but PARP-1 cleavage was detected in parental cells. IGFBP-3 treatment alone produced cleavage of caspases 7, 8, and 9 and PARP-1 in MCF-7 cells. IGFBP-3 failed to activate caspases in MCF-7/VDR cells; however PARP-1 cleavage was detected. 1, 25-D3 treatment inhibited IGF-I/Akt survival signalling in MCF-7 but not in MCF-7/VDR cells. In contrast, IGFBP-3 treatment was effective in inhibiting IGF-I/Akt pathways in both breast cancer lines. These results suggest a role for IGFBP-3 in 1, 25-D3 apoptotic signalling and that impaired secretion of IGFBP-3 may be involved in acquired resistance to vitamin D in breast cancer.
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28
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Azar WJ, Zivkovic S, Werther GA, Russo VC. IGFBP-2 nuclear translocation is mediated by a functional NLS sequence and is essential for its pro-tumorigenic actions in cancer cells. Oncogene 2013; 33:578-88. [PMID: 23435424 DOI: 10.1038/onc.2012.630] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 11/11/2012] [Accepted: 12/05/2012] [Indexed: 12/29/2022]
Abstract
IGFBP-2 is highly expressed in both the serum and tumor tissues of most cancers, and is considered one of the most significant genes in the signature of major cancers. IGFBP-2 mainly modulates IGF actions in the pericellular space; however, there is considerable evidence to suggest that IGFBP-2 may also act independently of the IGFs. These IGF-independent actions of IGFBP-2 are exerted either via interactions at the cell surface or intracellularly, via interaction with cytoplasmic or nuclear-binding partners. The precise mechanism underlying the intracellular/intranuclear localization of IGFBP-2 remains unclear. In this study, we investigated IGFBP-2 nuclear localization in several common cancer cells with the aim of dissecting the mechanism of its nuclear trafficking. IGFBP-2 is detected in the nuclei of common cancer cells, including breast, prostate and several neuroblastoma cell lines, using cell fractionation and confocal microscopy. Via nuclear import assays, we show that nuclear entry of IGFBP-2 is mediated by the classical nuclear import mechanisms, primarily through importin-α, as demonstrated by the use of blocking, competition and co-immunoprecipitation assays. Bioinformatics analysis of the IGFBP-2 protein sequence with PSORT II identified a classical nuclear localization signal (cNLS) sequence at 179PKKLRPP185, within the IGFBP-2 linker domain, mutagenesis of which abolishes IGFBP-2 nuclear import. Accordingly, the NLSmutIGFBP-2 fails to activate the VEGF promoter, which would otherwise occur in the presence of wild-type IGFBP-2. As a consequence, no activation of angiogenic processes were observed in NLSmutIGFBP-2 expressing SHEP cells when implanted onto our in vivo quail chorio-allantoic membrane model. Taken together, these data show for the first time that IGFBP-2 possesses a functional NLS sequence and that IGFBP-2 actively translocates into the nucleus by a classical nuclear import mechanism, involving formation of IGFBP-2 complexes with importin-α. Nuclear IGFBP-2 is required for the activation of VEGF expression and consequent angiogenesis.
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Affiliation(s)
- W J Azar
- 1] Hormone Research, Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia [2] Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia
| | - S Zivkovic
- Hormone Research, Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - G A Werther
- 1] Hormone Research, Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia [2] Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia
| | - V C Russo
- 1] Hormone Research, Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia [2] Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia
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29
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Wu YY, Yu T, Yang XY, Li F, Ma L, Yang Y, Liu XG, Wang YY, Gong P. Vitamin D3 and insulin combined treatment promotes titanium implant osseointegration in diabetes mellitus rats. Bone 2013; 52:1-8. [PMID: 22985888 DOI: 10.1016/j.bone.2012.09.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 09/01/2012] [Accepted: 09/03/2012] [Indexed: 01/08/2023]
Abstract
This study investigated the effect of insulin and vitamin D(3) (VD(3)) treatment on implant osseointegration in diabetic mellitus (DM) rats. DM was induced by administration of streptozotocin in rats, which received implants insertion in the femur. Then animals were subjected to different treatment and divided to the following group: control, diabetic, insulin-treated diabetic, VD(3)-treated diabetic, insulin and VD(3) combination-treated diabetic rats. The glucose levels and weight of rats were periodically evaluated, and serum 25(OH)D(3) levels in rats were measured at the end of the experiment. Animals were sacrificed at 12 weeks after surgery, the peri-implant trabecular microstructure, implant fixation and implant osseointegration were measured by microscopic computerized tomography (micro-CT) evaluation, push-out test and histomorphometric analysis. Diabetic rats displayed significantly higher blood glucose level, lower body weight, lower serum 25(OH)D(3) levels, and less implant osseointegration than controls. Insulin treatment showed restorative effect on body weight and serum 25(OH)D(3) levels of diabetic rats, but the blood glucose level in diabetic rats were still substantially higher compared to controls after 14 days therapy of insulin. Combined treatment restored hyperglycemia in diabetic rats to be normal, and reversed the impaired osseointegration capacity of implants, with the bone volume ratio and percent osseointegration increased by 1.37-fold and 1.6-fold in micro-CT evaluation, the maximal push-out force and ultimate shear strength by 1.3-fold and 2.1-fold in push-out test, and the bone-to-implant contact and bone area ratio increased by 2.57-fold and 1.44-fold in histomorphometric analysis. Monotreatment also enhanced implant fixation, but less. These results indicated that insulin and VD(3) combined treatment may be an effective approach to enhance implant fixation in diabetic rats, but whether the results could be extrapolated to human needs further study.
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Affiliation(s)
- Ying-ying Wu
- State Key Laboratory of Oral Disease, Sichuan University, No. 14, Sec. 3, Renminnan Road, Chengdu 610041, Sichuan, People's Republic of China
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30
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Ciciarello M, Zini R, Rossi L, Salvestrini V, Ferrari D, Manfredini R, Lemoli RM. Extracellular purines promote the differentiation of human bone marrow-derived mesenchymal stem cells to the osteogenic and adipogenic lineages. Stem Cells Dev 2012; 22:1097-111. [PMID: 23259837 DOI: 10.1089/scd.2012.0432] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Extracellular nucleotides are potent signaling molecules mediating cell-specific biological functions, mostly within the processes of tissue damage and repair and flogosis. We previously demonstrated that adenosine 5'-triphosphate (ATP) inhibits the proliferation of human bone marrow-derived mesenchymal stem cells (BM-hMSCs), while stimulating, in vitro and in vivo, their migration. Here, we investigated the effects of ATP on BM-hMSC differentiation capacity. Molecular analysis showed that ATP treatment modulated the expression of several genes governing adipogenic and osteoblastic (i.e., WNT-pathway-related genes) differentiation of MSCs. Functional studies demonstrated that ATP, under specific culture conditions, stimulated adipogenesis by significantly increasing the lipid accumulation and the expression levels of the adipogenic master gene PPARγ (peroxisome proliferator-activated receptor-gamma). In addition, ATP stimulated osteogenic differentiation by promoting mineralization and expression of the osteoblast-related gene RUNX2 (runt-related transcription factor 2). Furthermore, we demonstrated that ATP stimulated adipogenesis via its triphosphate form, while osteogenic differentiation was induced by the nucleoside adenosine, resulting from ATP degradation induced by CD39 and CD73 ectonucleotidases expressed on the MSC membrane. The pharmacological profile of P2 purinergic receptors (P2Rs) suggests that adipogenic differentiation is mainly mediated by the engagement of P2Y1 and P2Y4 receptors, while stimulation of the P1R adenosine-specific subtype A2B is involved in adenosine-induced osteogenic differentiation. Thus, we provide new insights into molecular regulation of MSC differentiation.
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Affiliation(s)
- Marilena Ciciarello
- Department of Hematology and Oncological Sciences, L. & A. Seràgnoli, Institute of Hematology, Stem Cell Research Center, Azienda Ospedaliero-Universitaria Policlinico S. Orsola-Malpighi, University of Bologna, Bologna, Italy.
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31
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Marshall PA, Hernandez Z, Kaneko I, Widener T, Tabacaru C, Aguayo I, Jurutka PW. Discovery of novel vitamin D receptor interacting proteins that modulate 1,25-dihydroxyvitamin D3 signaling. J Steroid Biochem Mol Biol 2012; 132:147-59. [PMID: 22626544 PMCID: PMC3408799 DOI: 10.1016/j.jsbmb.2012.05.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Revised: 04/03/2012] [Accepted: 05/04/2012] [Indexed: 12/24/2022]
Abstract
The nuclear vitamin D receptor (VDR) modulates gene transcription in 1,25-dihydroxyvitamin D(3) (1,25D) target tissues such as kidney, intestine, and bone. VDR is also expressed in heart, and 1,25D deficiency may play a role in the acceleration of cardiovascular disease. Employing a yeast two-hybrid system and a human heart library, using both a 1,25D-independent and 1,25D-dependent screen, we discovered six candidate VDR interacting proteins (VIPs). These novel VIPs include CXXC5, FASTK, NR4A1, TPM2, MYL3 and XIRP1. Mammalian two-hybrid assays as well as GST pull-downs were used to confirm VIP-VDR interaction, and the combination of these two assays reveals that CXXC5, XIRP1, FASTK and NR4A1 interactions with VDR may be modulated by 1,25D. The functional effects of these VIPs on 1,25D-mediated gene expression were explored in transcriptional assays employing three separate and distinct 1,25D-responsive element (VDRE)-driven luciferase reporter genes in transfected Caco-2 and HEK-293 cells, and in a C2C12 myoblast line. FASTK and TPM2 activated expression in all cell line and promoter contexts, while CXXC5 and XIRP1 exhibited differing effects depending on the cell line and promoter employed, suggesting promoter and cell-specific effects of these unique VIPs on VDR signaling. Further evaluation of the interaction between CXXC5 and VDR revealed that CXXC5 acts in a dose-dependent manner to stimulate VDR-mediated transcription on select VDREs. Identification of novel heart VIPs and their influence on VDR activity may increase our understanding of how vitamin D impacts cardiac physiology and may facilitate development of VDR/VIP drug analogs to combat heart disease.
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Affiliation(s)
- Pamela A. Marshall
- Division of Mathematical and Natural Sciences, Arizona State University, Glendale, AZ 85306, United States
| | - Zachary Hernandez
- Division of Mathematical and Natural Sciences, Arizona State University, Glendale, AZ 85306, United States
| | - Ichiro Kaneko
- Division of Mathematical and Natural Sciences, Arizona State University, Glendale, AZ 85306, United States
- Department of Basic Medical Sciences, The University of Arizona, College of Medicine, Phoenix, AZ, 85004, United States
| | - Tim Widener
- Division of Mathematical and Natural Sciences, Arizona State University, Glendale, AZ 85306, United States
- Department of Basic Medical Sciences, The University of Arizona, College of Medicine, Phoenix, AZ, 85004, United States
| | - Christa Tabacaru
- Division of Mathematical and Natural Sciences, Arizona State University, Glendale, AZ 85306, United States
| | - Izayadeth Aguayo
- Division of Mathematical and Natural Sciences, Arizona State University, Glendale, AZ 85306, United States
| | - Peter W. Jurutka
- Division of Mathematical and Natural Sciences, Arizona State University, Glendale, AZ 85306, United States
- Department of Basic Medical Sciences, The University of Arizona, College of Medicine, Phoenix, AZ, 85004, United States
- Corresponding author at: Division of Mathematical and Natural Sciences, Arizona State University, 4701 W. Thunderbird Rd., Glendale, AZ 85306, United States, Tel. +1 602 543 6087, fax: +1 602 543 6074. (P.W. Jurutka)
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Grkovic S, O'Reilly VC, Han S, Hong M, Baxter RC, Firth SM. IGFBP-3 binds GRP78, stimulates autophagy and promotes the survival of breast cancer cells exposed to adverse microenvironments. Oncogene 2012; 32:2412-20. [PMID: 22751133 DOI: 10.1038/onc.2012.264] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Despite the established role of insulin-like growth factor binding protein-3 (IGFBP-3) as a growth inhibitor in vitro, a high level of IGFBP-3 in breast tumor tissue is associated with the stimulation of xenograft growth in mice and poor prognosis in patients. To understand the contribution of IGFBP-3 to breast cancer progression, tandem affinity purification was used to identify novel interacting proteins. The endoplasmic reticulum protein, glucose-regulated protein 78 (GRP78), was shown to bind to IGFBP-3, confirmed by colocalization, coimmunoprecipitations, glutathione S-transferase (GST) pulldowns and a nanomolar binding affinity. GST pulldowns also indicated that the GRP78 ATPase domain mediated the interaction with IGFBP-3. The critical roles of GRP78 in the unfolded protein response and macroautophagy led to an investigation of possible links between IGFBP-3, GRP78 and cellular stress responses. IGFBP-3 was found to stimulate the survival of breast cancer cells subjected to glucose starvation and hypoxia. Pharmacological inhibitors and small interfering RNA knockdown established that the increased survival of IGFBP-3-expressing cells was dependent on an intact autophagy response, as well as GRP78. The contribution of autophagy was confirmed by the demonstration that IGFBP-3 expression increases both the formation of autophagic puncta and flux through the system. In conclusion, we have shown that IGFBP-3 stimulates autophagy and thereby promotes the survival of breast cancer cells exposed to conditions that represent the adverse microenvironments encountered by solid tumor cells in vivo.
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Affiliation(s)
- S Grkovic
- Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, St Leonards, New South Wales, Australia.
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Kuemmerle JF. Insulin-like growth factors in the gastrointestinal tract and liver. Endocrinol Metab Clin North Am 2012; 41:409-23, vii. [PMID: 22682638 PMCID: PMC3372868 DOI: 10.1016/j.ecl.2012.04.018] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The liver is a major source of insulin-like growth factors (IGFs) and IGF binding proteins (IGFBPs) that are present in the circulation and have important endocrine activities relating to energy metabolism, body size, carcinogenesis, and various organ-specific functions. Although IGFs have only minor effects on the normal liver itself, production of IGFs and IGFBPs in a tissue-specific manner in the gastrointestinal tract exert important regulatory effects on cellular proliferation, survival, and apoptosis. IGFs and IGFBPs play important regulatory roles in the response of both the liver and the gastrointestinal tract to inflammation and in the development of neoplasia.
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Affiliation(s)
- John F Kuemmerle
- Department of Medicine, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298-0341, USA.
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Abstract
Although the insulin-like growth factor (IGF) system is essential for normal growth and development, its dysregulation has been implicated in a range of pathological states. The peptide growth factors IGF-I and IGF-II exert their effects by binding to cell-surface heterotetrameric tyrosine kinase receptors and activating multiple intracellular signalling cascades, leading to changes in the expression of proteins essential for cell proliferation, survival and differentiation. The IGF system comprises multiple ligands, receptors and high-affinity IGF binding proteins (IGFBPs), with added complexity arising from crosstalk between its receptors and other key growth-regulatory pathways such as those activated by steroid hormones, integrins and other receptor tyrosine kinases. The IGFBPs are also increasingly recognised for their intrinsic growth-regulatory activity, and the ability of IGFBP-3 to modulate signalling pathways of nuclear hormone and growth factor receptors, as well as novel receptors, is believed to play a role both in normal physiology and in disease.
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Affiliation(s)
- Janet L Martin
- Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, St Leonards, Australia
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Qiu J, Ma XL, Wang X, Chen H, Huang BR. Insulin-like growth factor binding protein-6 interacts with the thyroid hormone receptor α1 and modulates the thyroid hormone-response in osteoblastic differentiation. Mol Cell Biochem 2011; 361:197-208. [PMID: 21997736 DOI: 10.1007/s11010-011-1104-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Accepted: 09/28/2011] [Indexed: 02/04/2023]
Abstract
Insulin-like growth factor binding protein-6 (IGFBP-6) is a member of the insulin-like growth factor binding protein family, which has both Insulin-like growth factor-dependent and independent effects on cell growth. In previous studies, we have shown that recombinant IGFBP-6 could be translocated into the cell nucleus. But the effect in the nucleus of IGFBP-6 is not clear. In the present study, we use multiple methodologies including Glutathione S-transferase pull-down assay, co-immunoprecipitation, fluorescence resonance energy transfer to demonstrate that IGFBP-6 can directly interact with thyroid hormone receptor alpha 1 (TRα1) in vitro and in vivo. We also demonstrate that the DNA-binding domains and Ligand-binding domains of TRα1 and N-terminal domains and C-terminal domains of IGFBP-6 are involved in the interaction. This interaction also can block the formation of TR: retinoid X receptor heterodimers. Furthermore, immunofluorescence co-localization studies show IGFBP-6 and TRα1 could co-localize in the nucleus of the cells. Reporter gene experiment shows that IGFBP-6 negatively regulates the growth hormone promoter activity induced by ligand activated TRα1. Moreover, real-time RT-PCR demonstrates that IGFBP-6 could inhibit the osteocalcin mRNA transcription induced by Triiodothyronine (3,3',5-Triiodo-L-thyronine, T3) in osteoblastic cells. Finally, alkaline phosphatase activity was significantly decreased in osteoblastic cells when the cells were transfected with IGFBP-6 in the presence of T3. In conclusion, these studies provide evidence that overexpression of IGFBP-6 suppresses osteoblastic differentiation regulated by TR in the present of T3.
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Affiliation(s)
- Jia Qiu
- National Laboratory of Medical Molecular Biology, Department of Biochemistry and Molecular Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
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36
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Ertek S, Francesco Cicero A, Erdoğan G. The relationship between calcium metabolism, insulin-like growth factor-1 and pulse pressure in normotensive, normolipidaemic and non-diabetic patients. Arch Med Sci 2011; 7:776-80. [PMID: 22291821 PMCID: PMC3258801 DOI: 10.5114/aoms.2011.25551] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 05/30/2011] [Accepted: 09/06/2011] [Indexed: 12/22/2022] Open
Abstract
INTRODUCTION Recent evidence suggests an interaction between bone metabolism and blood pressure (BP) regulation. The aim of our study was to evaluate endocrinological and metabolic factors related to pulse pressure (PP) in normotensive, normolipidaemic, non-smoker subjects. MATERIAL AND METHODS We consecutively enrolled 156 adults (37 males, 119 females) in summer 2009. The BP and body mass index (BMI) were recorded, and serum samples were taken for 25-hydroxy vitamin D (25-OHD), insulin-like growth factor-1 (IGF-1), growth hormone (GH), parathormone (PTH), calcium, albumin, phosphorus, glucose, triglyceride and cholesterol levels. RESULTS In the postmenopausal group, PP was significantly associated with age and BMI, while in premenopausal patients it was inversely related to ionized calcium. In men, a reverse relationship was present between GH and IGF-1 levels and PP. CONCLUSIONS The PP was predicted by different parameters in different genders and these predictors change even in the same gender before and after menopause. Well-known predictors of PP such as age and BMI were more pronounced in postmenopausal women, but none of the groups showed a relationship between PP and 25-OHD or PTH.
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Affiliation(s)
- Sibel Ertek
- Department of Endocrinology and Metabolic Diseases, Ufuk University Medical Faculty, Ankara, Turkey
| | - Arrigo Francesco Cicero
- Internal Medicine, Aging and Kidney Diseases Department, Atherosclerosis and Metabolic Diseases Research Center, Bologna University, Bologna, Italy
| | - Gürbüz Erdoğan
- Department of Endocrinology and Metabolic Diseases, Ufuk University Medical Faculty, Ankara, Turkey
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Azar WJ, Azar SHX, Higgins S, Hu JF, Hoffman AR, Newgreen DF, Werther GA, Russo VC. IGFBP-2 enhances VEGF gene promoter activity and consequent promotion of angiogenesis by neuroblastoma cells. Endocrinology 2011; 152:3332-42. [PMID: 21750048 DOI: 10.1210/en.2011-1121] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
IGF binding protein (IGFBP)-2 is one of the most significant genes in the signature of major aggressive cancers. Previously, we have shown that IGFBP-2 enhances proliferation and invasion of neuroblastoma cells, suggesting that IGFBP-2 activates a protumorigenic gene expression program in these cells. Gene expression profiling in human neuroblastoma SK-N-SHEP (SHEP)-BP-2 cells indicated that IGFBP-2 overexpression activated a gene expression program consistent with enhancement of tumorigenesis. Regulation was significant for genes involved in proliferation/survival, migration/adhesion, and angiogenesis, including the up-regulation of vascular endothelial growth factor (VEGF) mRNA (>2-fold). Specific transcriptional activation of the VEGF gene by IGFBP-2 overexpression was demonstrated via cotransfection of a VEGF promoter Luciferase construct in SHEP-BP-2. Cotransfection of VEGF promoter Luciferase construct with IGFBP-2 protein in wild-type SHEP cells indicated that transactivation of VEGF promoter only occurs in the presence of intracellular IGFBP-2. Cell fractionation and immunofluorescence in SHEP-BP-2 cells demonstrated nuclear localization of IGFBP-2. These findings suggest that transcriptional activation of VEGF promoter is likely to be mediated by nuclear IGFBP-2. The levels of secreted VEGF (up to 400 pg/10(6) cells) suggested that VEGF might elicit angiogenic activity. Hence, SHEP-BP-2 cells and control clones cultured in collagen sponge were xenografted onto chick embryo chorioallantoic membrane. Neomicrovascularization was observed by 72 h, solely in the SHEP-BP-2 cell xenografts. In conclusion, our data indicate that IGFBP-2 is an activator of aggressive behavior in cancer cells, involving nuclear entry and activation of a protumorigenic gene expression program, including transcriptional regulation of the VEGF gene and consequent proangiogenic activity of NB cell xenografts in vivo.
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Affiliation(s)
- Walid J Azar
- Centre for Hormone Research, Cell Biology, Murdoch Childrens Research Institute, Royal Children's Hospital, Flemington Road, Parkville 3052, Victoria, Australia
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Cui J, Ma C, Qiu J, Ma X, Wang X, Chen H, Huang B. A novel interaction between insulin-like growth factor binding protein-6 and the vitamin D receptor inhibits the role of vitamin D3 in osteoblast differentiation. Mol Cell Endocrinol 2011; 338:84-92. [PMID: 21458526 DOI: 10.1016/j.mce.2011.03.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2010] [Revised: 01/25/2011] [Accepted: 03/10/2011] [Indexed: 01/24/2023]
Abstract
Insulin-like growth factor binding protein-6 (IGFBP-6) is a secreted glycoprotein that reduces the bioavailability of IGFs. It has both IGF-dependent and -independent effects on cell growth, however the mechanisms responsible for its IGF-independent actions of IGFBP-6 are not fully understood. In previous studies, we have shown that recombinant IGFBP-6 can be internalized and translocated to the nucleus. The present study shows that IGFBP-6 interacts with the vitamin D receptor (VDR). Physical interactions between IGFBP-6 and the VDR were confirmed by GST pulldown and co-immunoprecipitation assays. We also determined that the interaction binding sites were on the C-terminal region of the VDR. This interaction can influence retinoid X receptor (RXR):VDR heterodimerization. Furthermore, immunofluorescence colocalization studies showed that IGFBP-6 colocalized with the VDR predominantly in the cell's nucleus. Inductions of osteocalcin and growth hormone promoter activities by 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) were significantly decreased when cells were co-transfected with IGFBP-6 and the VDR compared with cells transfected with the VDR only. Moreover, we found that alkaline phosphatase activity (ALP, a general marker of osteoblast differentiation) was significantly decreased in osteoblast-like cells when they were transfected with IGFBP-6 in the presence of 1,25(OH)(2)D(3). No obvious difference in ALP activity was observed when cells were transfected with IGFBP-6 and endogenous VDR was knocked down by siRNA. These results demonstrate that IGFBP-6 inhibits osteoblastic differentiation mediated by 1,25(OH)(2)D(3) and the VDR through interacting with the VDR and inhibiting its function. This is a novel mechanism for IGFBP-6.
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Affiliation(s)
- Jian Cui
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
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Paharkova-Vatchkova V, Lee KW. Nuclear export and mitochondrial and endoplasmic reticulum localization of IGF-binding protein 3 regulate its apoptotic properties. Endocr Relat Cancer 2010; 17:293-302. [PMID: 20228135 PMCID: PMC3174094 DOI: 10.1677/erc-09-0106] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Tumor suppression by IGF-binding protein 3 (IGFBP3) may occur in an IGF-independent manner, in addition to its role as a regulator of IGF bioavailability. After secretion, IGFBP3 is internalized, rapidly localized to the nucleus, and is later detected in the cytoplasm. We identified a putative nuclear export sequence (NES) in IGFBP3 between amino acids 217 and 228, analogous to the leucine-rich NES sequence of p53 and HIV Rev. Mutation of the NES prevents nucleocytoplasmic shuttling of IGFBP3 and blocks its ability to induce apoptosis. Targeting of IGFBP3 to the mitochondria and endoplasmic reticulum (ER) was confirmed by co-localization with organelle markers using fluorescence confocal microscopy and subcellular fractionation. Mitochondrial targeting was also demonstrated in vivo in IGFBP3-treated prostate cancer xenografts. These results show that IGFBP3 shuttles from the nucleus to the mitochondria and ER, and that nuclear export is essential for its effects on prostate cancer apoptosis.
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Affiliation(s)
- Vladislava Paharkova-Vatchkova
- Division of Pediatric Endocrinology, David Geffen School of Medicine at UCLA, Mattel Children's Hospital, Los Angeles, California 90095, USA
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40
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Shaikh N, Russo L, Papaleo E, Giannoni P, De Gioia L, Nicotra F, Quarto R, Cipolla L. C-type natriuretic peptide: Structural studies, fragment synthesis, and preliminary biological evaluation in human osteosarcoma cell lines. Biopolymers 2010; 94:213-9. [DOI: 10.1002/bip.21336] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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41
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Baxter RC, Twigg SM. Actions of IGF binding proteins and related proteins in adipose tissue. Trends Endocrinol Metab 2009; 20:499-505. [PMID: 19801194 DOI: 10.1016/j.tem.2009.07.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2009] [Revised: 07/06/2009] [Accepted: 07/07/2009] [Indexed: 12/14/2022]
Abstract
The insulin-like growth factors (IGFs), their binding proteins (IGFBPs) and structurally related proteins have been identified in adipose tissue but their roles in adipose tissue are poorly understood. IGF-I and IGFBP-3 expression increase during human preadipocyte differentiation. However, whereas IGF-I stimulates this process, IGFBP-3 is inhibitory both to preadipocyte differentiation and to differentiated adipocyte function. The direct interaction of IGFBP-3 with peroxisome proliferator-activated receptor-gamma is believed to contribute to its inhibitory effect on differentiation. Connective tissue growth factor (CTGF/CCN2) shares weak structural homology and functional similarities with IGFBP-3, including inhibition of preadipocyte differentiation. This review examines the current knowledge of IGFBP regulation and actions in adipocytes and proposes a common regulatory pathway involving IGFBP-3 and CTGF/CCN2.
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Affiliation(s)
- Robert C Baxter
- Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, St. Leonards NSW 2065, Australia.
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Flynn RS, Mahavadi S, Murthy KS, Kellum JM, Kuemmerle JF. Insulin-like growth factor-binding protein-5 stimulates growth of human intestinal muscle cells by activation of G{alpha}i3. Am J Physiol Gastrointest Liver Physiol 2009; 297:G1232-8. [PMID: 19808657 PMCID: PMC2850095 DOI: 10.1152/ajpgi.00323.2009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In human intestinal smooth muscle cells, endogenous insulin-like growth factor-I (IGF-I) regulates growth and IGF-binding protein-5 (IGFBP-5) expression. The effects of IGF-I are facilitated by IGFBP-5. We previously showed that IGFBP-5 acts independently of IGF-I in human intestinal muscle to stimulate proliferation and upregulate IGF-I production by activation of Erk1/2 and p38 MAPK. Thus a positive feedback loop exists between IGF-I and IGFBP-5, whereby both stimulate muscle growth and production of the other factor. In Crohn's disease, IGF-I and IGFBP-5 expression are increased and contribute to stricture formation through this effect on muscle growth. To determine the signaling pathways coupling IGFBP-5 to MAPK activation and growth, smooth muscle cells were isolated from muscularis propria of human intestine and placed into primary culture. Erk1/2 and p38 MAPK activation and type I collagen production were measured by immunoblot. Proliferation was measured by [(3)H]thymidine incorporation. Activation of specific G proteins was measured by ELISA. AG1024, an IGF-I receptor tyrosine kinase inhibitor, was used to isolate the IGF-I-independent effects of IGFBP-5. IGFBP-5-induced phosphorylation of Erk1/2 and p38 MAPK and proliferation were abolished by pertussis toxin, implying the participation of Gi. IGFBP-5 specifically activated Gi3 but not other G proteins. Transfection of an inhibitory Galphai minigene specifically inhibited MAPK activation, proliferation, and both collagen-I and IGF-I production. Our results indicate that endogenous IGFBP-5 activates Gi3 and regulates smooth muscle growth, IGF-I production, and collagen production via the alpha-subunit of Gi3, independently of IGF-I, in normal human intestinal muscle cells.
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Affiliation(s)
| | | | | | - John M. Kellum
- 3Surgery, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia
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43
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Abstract
This paper reviews the current understanding of the vitamin D-induced differentiation of neoplastic cells, which results in the generation of cells that acquire near-normal, mature phenotype. Examples of the criteria by which differentiation is recognized in each cell type are provided, and only those effects of 1alpha,25-dihydroxyvitamin D(3) (1,25D) on cell proliferation and survival that are associated with the differentiation process are emphasized. The existing knowledge, often fragmentary, of the signaling pathways that lead to vitamin D-induced differentiation of colon, breast, prostate, squamous cell carcinoma, osteosarcoma, and myeloid leukemia cancer cells is outlined. The important distinctions between the different mechanisms of 1,25D-induced differentiation that are cell-type and cell-context specific are pointed out where known. There is a considerable body of evidence that the principal human cancer cells can be suitable candidates for chemoprevention or differentiation therapy with vitamin D. However, further studies are needed to fully understand the underlying mechanisms in order to improve the therapeutic approaches.
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Affiliation(s)
- Elzbieta Gocek
- Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
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44
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Chan SSY, Schedlich LJ, Twigg SM, Baxter RC. Inhibition of adipocyte differentiation by insulin-like growth factor-binding protein-3. Am J Physiol Endocrinol Metab 2009; 296:E654-63. [PMID: 19141684 DOI: 10.1152/ajpendo.90846.2008] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Insulin-like growth factor-binding protein-3 (IGFBP-3) interacts with the type II nuclear receptors retinoid X receptor (RXR)alpha and retinoic acid receptor-alpha and modulates their transcriptional activity. Peroxisome proliferator-activated receptor (PPAR)gamma, a related nuclear receptor that dimerizes with RXRalpha, plays an important role in adipocyte differentiation. IGFBP-3 is regulated during adipocyte differentiation, but its role in this process is unknown. We demonstrate that IGFBP-3 interferes with the PPARgamma-dependent processes of adipocyte differentiation and maintenance of the gene expression characteristic of mature adipocytes. Treatment of adipocytes with exogenous IGFBP-3, but not an IGFBP-3 mutant that does not bind RXRalpha or PPARgamma, decreased markers of adipocyte differentiation, PPARgamma, and resistin but increased the preadipocyte marker plasminogen activator inhibitor-1. Furthermore, expression of human IGFBP-3, but not the IGFBP-3 mutant, by preadipocytes inhibited preadipocyte differentiation as determined by gene markers and lipid accumulation. IGFBP-3 interacted with PPARgamma in vitro and in 3T3-L1 adipocyte lysates and inhibited PPARgamma heterodimerization with RXRalpha in vitro. Wild-type IGFBP-3, but not mutant IGFBP-3, blocked ligand-induced transactivation of PPAR response element in 3T3-L1 cells. The observation that IGFBP-3 inhibits adipocyte differentiation and impacts on the PPARgamma system suggests a role for IGFBP-3 in the pathogenesis of obesity and insulin resistance.
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Affiliation(s)
- Sophie S Y Chan
- Kolling Institute of Medical Research, Royal North Shore Hospital, and Discipline of Medicine, University of Sydney, St Leonards, NSW 2065, Australia
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45
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Tripathi G, Salih DAM, Drozd AC, Cosgrove RA, Cobb LJ, Pell JM. IGF-independent effects of insulin-like growth factor binding protein-5 (Igfbp5) in vivo. FASEB J 2009; 23:2616-26. [PMID: 19332648 DOI: 10.1096/fj.08-114124] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
IGF activity is regulated tightly by a family of IGF binding proteins (IGFBPs). IGFBP-5 is the most conserved of these and is up-regulated significantly during differentiation of several key lineages and in some cancers. The function of IGFBP-5 in these physiological and pathological situations is unclear, however, several IGFBP-5 sequence motifs and studies in vitro suggest IGF-independent actions. Therefore, we aimed to compare the phenotypes of mice overexpressing wild-type Igfbp5 or an N-terminal mutant Igfbp5 with negligible IGF binding affinity. Both significantly inhibited growth, even at low expression levels. Even though wild-type IGFBP-5 severely disrupted the IGF axis, we found no evidence for interaction of mutant IGFBP-5 with the IGF system. Further, overexpression of wild-type IGFBP-5 rescued the lethal phenotype induced by "excess" IGF-II in type 2 receptor-null mice; mutant IGFBP-5 overexpression could not. Therefore, wild-type IGFBP-5 provides a very effective mechanism for the inhibition of IGF activity and a powerful in vivo mechanism to inhibit IGF activity in pathologies such as cancer. This study is also the first to suggest significant IGF-independent actions for IGFBP-5 during development.
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Affiliation(s)
- Gyanendra Tripathi
- Laboratory of Molecular Signalling, The Babraham Institute, Cambridge CB22 3AT, UK
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46
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Strohbach C, Kleinman S, Linkhart T, Amaar Y, Chen ST, Mohan S, Strong D. Potential involvement of the interaction between insulin-like growth factor binding protein (IGFBP)-6 and LIM mineralization protein (LMP)-1 in regulating osteoblast differentiation. J Cell Biochem 2008; 104:1890-905. [PMID: 18395833 DOI: 10.1002/jcb.21761] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Insulin-like growth factor binding protein (IGFBP)-6 has been reported to inhibit differentiation of myoblasts and osteoblasts. In the current study, we explored the mechanisms underlying IGFBP-6 effects on osteoblast differentiation. During MC3T3-E1 osteoblast differentiation, we found that IGFBP-6 protein was down-regulated. Overexpression of IGFBP-6 in MC3T3-E1 and human bone cells inhibited nodule formation, osteocalcin mRNA expression and ALP activity. Furthermore, accumulation of IGFBP-6 in the culture media was not required for any of these effects suggesting that IGFBP-6 suppressed osteoblast differentiation by an intracellular mechanism. A yeast two-hybrid screen of an osteosarcoma library was conducted to identify intracellular binding partners to account for IGFBP-6 inhibitory effects on osteoblast differentiation. LIM mineralizing protein (LMP-1) was identified as a high affinity IGFBP-6 binding partner. Physical interaction between IGFBP-6 and LMP-1 was confirmed by co-immunoprecipitation. Fluorescent protein fusion constructs for LMP-1 and IGFBP-6 were transiently transfected into osteoblasts to provide evidence of subcellular locations for each protein. Coexpression of LMP-1-GFP and IGFBP-6-RFP resulted in overlapping subcellular localization of LMP-1 and IGFBP-6. To determine if there was a functional association of IGFBP-6 and LMP-1 as well as a physical association, we studied the effect of IGFBP-6, LMP-1 and their combination on type I procollagen promoter activity. LMP-1 increased promoter activity while IGFBP-6 reduced promoter activity, and coexpression of LMP-1 with IGFBP-6 abrogated IGFBP-6 suppression. These studies provide evidence that overexpression of IGFBP-6 suppresses human and murine osteoblast differentiation, that IGFBP-6 and LMP-1 physically interact, and supports the conclusion that this interaction may be functionally relevant.
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Affiliation(s)
- Cassandra Strohbach
- Jerry L. Pettis Memorial VA Center, Musculoskeletal Disease Center, Loma Linda, CA 92357, USA
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47
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Pérez-Casellas LA, Wang X, Howard KD, Rehage MW, Strong DD, Linkhart TA. Nuclear factor I transcription factors regulate IGF binding protein 5 gene transcription in human osteoblasts. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2008; 1789:78-87. [PMID: 18809517 DOI: 10.1016/j.bbagrm.2008.08.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Revised: 08/11/2008] [Accepted: 08/26/2008] [Indexed: 11/17/2022]
Abstract
Insulin-like growth factor binding protein 5 (IGFBP5) is expressed in many cell types including osteoblasts and modulates IGF activities. IGFBP5 may affect osteoblasts and bone formation, in part by mechanisms independent of binding IGFs. The highly conserved IGFBP5 proximal promoter within 100 nucleotides of the start of transcription contains functional cis regulatory elements for C/EBP, Myb and AP-2. We report evidence for a functional Nuclear Factor I (NFI) cis element that mediates activation or repression of IGFBP5 transcription by the NFI gene family. All four NFI genes were expressed in human osteoblast cultures and osteosarcoma cell lines. Co-transfection with human IGFBP5 promoter luciferase reporter and murine Nfi expression vectors showed that Nfib was the most active in stimulating transcription. Nfix was less active and Nfia and Nfic were inhibitory. Knockdown of NFIB and NFIC expression using siRNA decreased and increased IGFBP5 expression, respectively. Analysis of IGFBP5 promoter deletion and mutation reporter constructs identified a functional NFI cis element. All four NFI proteins bound the NFI site in electrophoretic mobility shift experiments and NFIB bound in chromatin immunoprecipitation assays. Results suggest that NFI proteins are important regulators of IGFBP5 expression in human osteoblasts and thus in modulating IGFBP5 functions in bone.
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Rolland Y, Abellan van Kan G, Bénétos A, Blain H, Bonnefoy M, Chassagne P, Jeandel C, Laroche M, Nourhashémi F, Orcel P, Piette F, Ribot C, Ritz P, Roux C, Taillandier J, Trémollières F, Weryha G, Vellas B. Frailty, osteoporosis and hip fracture: causes, consequences and therapeutic perspectives. J Nutr Health Aging 2008; 12:335-46. [PMID: 18443717 DOI: 10.1007/bf02982665] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
OBJECTIVE The aim of this review of the literature is to report the factors which both contribute to the frailty syndrome and increase hip fracture risk in the elderly. This work is the fruit of common reflection by geriatricians, endocrinologists, gynecologists and rheumatologists, and seeks to stress the importance of detection and management of the various components of frailty in elderly subjects who are followed and treated for osteoporosis. It also sets out to heighten awareness of the need for management of osteoporosis in the frail elderly. DESIGN The current literature on frailty and its links with hip fracture was reviewed and discussed by the group. RESULTS The factors and mechanisms which are common to both osteoporosis and frailty (falls, weight loss, sarcopenia, low physical activity, cognitive decline, depression, hormones such as testosterone, estrogens, insulin-like growth factor-I (IGF-I), growth hormone (GH), vitamin D and pro-inflammatory cytokines) were identified. The obstacles to access to diagnosis and treatment of osteoporosis in the frail elderly population and common therapeutic pathways for osteoporosis and frailty were discussed. CONCLUSION Future research including frail subjects would improve our understanding of how management of frailty can can contribute to lower the incidence of fractures. In parallel, more systematic management of osteoporosis should reduce the risk of becoming frail in the elderly population.
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Affiliation(s)
- Y Rolland
- Inserm U558, F-31073, Université de Toulouse III, France.
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Mukherjee A, Rotwein P. Insulin-like growth factor-binding protein-5 inhibits osteoblast differentiation and skeletal growth by blocking insulin-like growth factor actions. Mol Endocrinol 2008; 22:1238-50. [PMID: 18292241 DOI: 10.1210/me.2008-0001] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Signaling through the IGF-I receptor by locally synthesized IGF-I or IGF-II is critical for normal skeletal development and for bone remodeling and repair throughout the lifespan. In most tissues, IGF actions are modulated by IGF-binding proteins (IGFBPs). IGFBP-5 is the most abundant IGFBP in bone, and previous studies have suggested that it may either enhance or inhibit osteoblast differentiation in culture and may facilitate or block bone growth in vivo. To resolve these contradictory observations and discern the mechanisms of action of IGFBP-5 in bone, we studied its effects in differentiating osteoblasts and in primary bone cultures. Purified wild-type (WT) mouse IGFBP-5 or a recombinant adenovirus expressing IGFBP-5WT each prevented osteogenic differentiation induced by the cytokine bone morphogenetic protein (BMP)-2 at its earliest stages without interfering with BMP-mediated signaling, whereas an analog with reduced IGF binding (N domain mutant) was ineffective. When added at later phases of bone cell maturation, IGFBP-5WT but not IGFBP-5N blocked mineralization, prevented longitudinal growth of mouse metatarsal bones in short-term primary culture, and inhibited their endochondral ossification. Because an IGF-I variant (R3IGF-I) with diminished affinity for IGFBPs promoted full osteogenic differentiation in the presence of IGFBP-5WT, our results show that IGFBP-5 interferes with IGF action in osteoblasts and provides a framework for discerning mechanisms of collaboration between signal transduction pathways activated by BMPs and IGFs in bone.
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Affiliation(s)
- Aditi Mukherjee
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239, USA
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