1
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Frost HR. Variance-adjusted Mahalanobis (VAM): a fast and accurate method for cell-specific gene set scoring. Nucleic Acids Res 2020; 48:e94. [PMID: 32633778 PMCID: PMC7498348 DOI: 10.1093/nar/gkaa582] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 06/10/2020] [Accepted: 06/26/2020] [Indexed: 12/26/2022] Open
Abstract
Statistical analysis of single cell RNA-sequencing (scRNA-seq) data is hindered by high levels of technical noise and inflated zero counts. One promising approach for addressing these challenges is gene set testing, or pathway analysis, which can mitigate sparsity and noise, and improve interpretation and power, by aggregating expression data to the pathway level. Unfortunately, methods optimized for bulk transcriptomics perform poorly on scRNA-seq data and progress on single cell-specific techniques has been limited. Importantly, no existing methods support cell-level gene set inference. To address this challenge, we developed a new gene set testing method, Variance-adjusted Mahalanobis (VAM), that integrates with the Seurat framework and can accommodate the technical noise, sparsity and large sample sizes characteristic of scRNA-seq data. The VAM method computes cell-specific pathway scores to transform a cell-by-gene matrix into a cell-by-pathway matrix that can be used for both data visualization and statistical enrichment analysis. Because the distribution of these scores under the null of uncorrelated technical noise has an accurate gamma approximation, both population and cell-level inference is supported. As demonstrated using simulated and real scRNA-seq data, the VAM method provides superior classification accuracy at a lower computation cost relative to existing single sample gene set testing approaches.
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Affiliation(s)
- Hildreth Robert Frost
- Department of Biomedical Data Science, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA
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2
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Secretome of Olfactory Mucosa Mesenchymal Stem Cell, a Multiple Potential Stem Cell. Stem Cells Int 2016; 2016:1243659. [PMID: 26949398 PMCID: PMC4753338 DOI: 10.1155/2016/1243659] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Revised: 12/05/2015] [Accepted: 12/24/2015] [Indexed: 12/19/2022] Open
Abstract
Nasal olfactory mucosa mesenchymal stem cells (OM-MSCs) have the ability to promote regeneration in the nervous system in vivo. Moreover, with view to the potential for clinical application, OM-MSCs have the advantage of being easily accessible from patients and transplantable in an autologous manner, thus eliminating immune rejection and contentious ethical issues. So far, most studies have been focused on the role of OM-MSCs in central nervous system replacement. However, the secreted proteomics of OM-MSCs have not been reported yet. Here, proteins secreted by OM-MSCs cultured in serum-free conditions were separated on SDS-PAGE and identified by LC-MS/MS. As a result, a total of 274 secreted proteins were identified. These molecules are known to be important in neurotrophy, angiogenesis, cell growth, differentiation, and apoptosis, and inflammation which were highly correlated with the repair of central nervous system. The proteomic profiling of the OM-MSCs secretome might provide new insights into their nature in the neural recovery. However, proteomic analysis for clinical biomarkers of OM-MSCs needs to be further studied.
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3
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Pickard A, McCance DJ. IGF-Binding Protein 2 - Oncogene or Tumor Suppressor? Front Endocrinol (Lausanne) 2015; 6:25. [PMID: 25774149 PMCID: PMC4343188 DOI: 10.3389/fendo.2015.00025] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 02/13/2015] [Indexed: 01/08/2023] Open
Abstract
The role of insulin-like growth factor binding protein 2 (IGFBP2) in cancer is unclear. In general, IGFBP2 is considered to be oncogenic and its expression is often observed to be elevated in cancer. However, there are a number of conflicting reports in vitro and in vivo where IGFBP2 acts in a tumor suppressor manner. In this mini-review, we discuss the factors influencing the variation in IGFBP2 expression in cancer and our interpretation of these findings.
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Affiliation(s)
- Adam Pickard
- Centre for Cancer Research and Cell Biology, Queen’s University, Belfast, UK
- *Correspondence: Adam Pickard, Centre for Cancer Research and Cell Biology, Queen’s University Belfast, 97 Lisburn Road, Belfast BT7 9BL, UK e-mail:
| | - Dennis J. McCance
- Centre for Cancer Research and Cell Biology, Queen’s University, Belfast, UK
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4
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Chesik D, De Keyser J, Bron R, Fuhler GM. Insulin-like growth factor binding protein-1 activates integrin-mediated intracellular signaling and migration in oligodendrocytes. J Neurochem 2010; 113:1319-30. [PMID: 20345750 DOI: 10.1111/j.1471-4159.2010.06703.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In multiple sclerosis (MS), oligodendrocytes in lesions are lost, leaving damaged tissue virtually devoid of these myelin-producing cells. Our group has recently demonstrated enhanced expression of insulin-like growth factor (IGF) binding protein-1 (IGFBP-1) in oligodendrocytes (CNPase(+)) localized adjacent to MS lesions. In the present study, we demonstrate IGF-1-independent actions of IGFBP-1 on OLN-93 oligodendroglial cells, including activation of kinases ERK1/2, focal adhesion kinase and p21-activated kinase as well as small monomeric GTPases Rac and Ral. Activation of these intracellular signaling components was inhibited by GRGDS peptide, indicating signaling through integrin receptors. While both IGF-1 and IGFBP-1 demonstrated rapid induction of actin polymerization, IGFBP-1 proved to be a more potent inducer of migration than IGF-1, inducing a threefold increased migration rate. Furthermore, through integrin receptor signaling IGFBP-1 induced rapid transient translocalization of intracellular Rac toward punctuated structures followed by translocation of Rac to the plasma membrane. Our results suggest that up-regulation of IGFBP-1 in oligodendrocytes in MS may serve two functions: (i) regulate IGF-1 actions, (ii) exert IGF-independent effects through its RGD sequence.
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Affiliation(s)
- Daniel Chesik
- Department of Neurology, University Medical Center Groningen, Groningen, The Netherlands.
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5
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Liu Y, Teng X, Yang X, Song Q, Lu R, Xiong J, Liu B, Zeng N, Zeng Y, Long J, Cao R, Lin Y, He Q, Chen P, Lu M, Liang S. Shotgun Proteomics and Network Analysis between Plasma Membrane and Extracellular Matrix Proteins from Rat Olfactory Ensheathing Cells. Cell Transplant 2010; 19:133-46. [PMID: 20350363 DOI: 10.3727/096368910x492607] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Olfactory ensheathing cells (OECs) are a special type of glial cells that have characteristics of both astrocytes and Schwann cells. Evidence suggests that the regenerative capacity of OECs is induced by soluble, secreted factors that influence their microenvironment. These factors may regulate OECs self-renewal and/or induce their capacity to augment spinal cord regeneration. Profiling of plasma membrane and extracellular matrix through a high-throughput expression proteomics approach was undertaken to identify plasma membrane and extracellular matrix proteins of OECs under serum-free conditions. 1D-shotgun proteomics followed with gene ontology (GO) analysis was used to screen proteins from primary culture rat OECs. Four hundred and seventy nonredundant plasma membrane proteins and 168 extracellular matrix proteins were identified, the majority of which were never before reported to be produced by OECs. Furthermore, plasma membrane and extracellular proteins were classified based on their protein–protein interaction predicted by STRING quantitatively integrates interaction data. The proteomic profiling of the OECs plasma membrane proteins and their connection with the secretome in serum-free culture conditions provides new insights into the nature of their in vivo microenvironmental niche. Proteomic analysis for the discovery of clinical biomarkers of OECs mechanism warrants further study.
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Affiliation(s)
- Yisong Liu
- Key laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, P.R. China
| | - Xiaohua Teng
- Department of Neurosurgery, Second Affiliated Hospital of Hunan Normal University (163 Hospital of PLA), Changsha, P.R. China
| | - Xiaoxu Yang
- Key laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, P.R. China
| | - Qing Song
- Key laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, P.R. China
| | - Rong Lu
- Key laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, P.R. China
| | - Jixian Xiong
- Key laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, P.R. China
| | - Bo Liu
- Department of Neurosurgery, Second Affiliated Hospital of Hunan Normal University (163 Hospital of PLA), Changsha, P.R. China
| | - Nianju Zeng
- Department of Neurosurgery, Second Affiliated Hospital of Hunan Normal University (163 Hospital of PLA), Changsha, P.R. China
| | - Yu Zeng
- Department of Neurosurgery, Second Affiliated Hospital of Hunan Normal University (163 Hospital of PLA), Changsha, P.R. China
| | - Jia Long
- Key laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, P.R. China
| | - Rui Cao
- Key laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, P.R. China
| | - Yong Lin
- Key laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, P.R. China
| | - Quanze He
- Key laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, P.R. China
| | - Ping Chen
- Key laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, P.R. China
| | - Ming Lu
- Department of Neurosurgery, Second Affiliated Hospital of Hunan Normal University (163 Hospital of PLA), Changsha, P.R. China
| | - Songping Liang
- Key laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, P.R. China
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6
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Chesik D, De Keyser J. Progesterone and dexamethasone differentially regulate the IGF-system in glial cells. Neurosci Lett 2009; 468:178-82. [PMID: 19853640 DOI: 10.1016/j.neulet.2009.10.051] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Revised: 10/01/2009] [Accepted: 10/15/2009] [Indexed: 10/20/2022]
Abstract
IGF-1 is an important factor for myelin synthesis and hence possesses therapeutic potential in treating demyelinating disease such as multiple sclerosis. However, IGF-1 poorly crosses the blood-brain barrier. In this study, we investigated the effects of the sex steroid progesterone and the glucocorticoid dexamethasone on regulation of the IGF-system in glial cells. By means of quantitative PCR analysis, we demonstrate that progesterone upregulates IGF-1, the type 1 IGF receptor and IGFBP-2 in primary rat astrocytes and both IGF-1 and IGFBP-6 in OLN-93 oligodendroglial progenitor cells. In contrast, dexamethasone showed a negative effect on expression of IGF-1, the type 1 IGF receptor and the respective IGF binding proteins in both cell types. In oligodendrocytes, the differentiation marker CNPase was positively regulated by progesterone and negatively regulated by dexamethasone. Further, oligodendroglial cell migration was enhanced approximately 4-fold by progesterone. This study implicates progesterone as a positive regulator of IGF-system in glial cells and demonstrates a further biological function of progesterone in oligodendrocyte biology, namely stimulation of progenitor cell migration. Dexamethasone, on the other hand, is a negative regulator of the IGF-system in glial cells.
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Affiliation(s)
- Daniel Chesik
- Department of Neurology, University Medical Center Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands.
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7
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Rorive S, Berton A, D'haene N, Takacs CN, Debeir O, Decaestecker C, Salmon I. Matrix metalloproteinase-9 interplays with the IGFBP2-IGFII complex to promote cell growth and motility in astrocytomas. Glia 2009; 56:1679-90. [PMID: 18563800 DOI: 10.1002/glia.20719] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Insulin-like growth factor II (IGFII) acts as a potent mitogen for several tumor types and has been reported to positively influence astrocytoma cell growth and motility. In the central nervous system, IGFII bioavailability is mainly modulated by insulin-like growth factor binding protein 2 (IGFBP2), which sequestrates IGFII and therefore prevents its interaction with the type-1 IGF receptor (IGF-IR). Proteolysis of IGFBP2 is the predominant mechanism recognized to reduce the binding affinity of IGFBP2 for IGFII, thus favoring dissociation of IGFII from the IGFBP2-IGFII complex. It is known that certain proteases involved in astrocytoma malignancy, such as matrix metalloproteinase-7 (MMP-7), plasmin, and cathepsin D, are able to proteolyze IGFBP2 in vitro. The present study aims to investigate whether other proteases expressed by astrocytomas, specifically MMP-2, MMP-9, and membrane-type 1 matrix metalloprotease (MT1-MMP), are able to proteolyze the IGFBP2-IGFII complex. Our results show the following: (i) MMP-9 proteolyzes the IGFBP2-IGFII complex in vitro, while MMP-2 and MT1-MMP do not; (ii) this MMP-9-induced IGFBP2-IGFII complex proteolysis releases free IGFII, which contributes to enhance the motility and the growth of LN229 astrocytoma cells. Furthermore, this study also highlights that the formation of the IGFBP2-IGFII complex inhibits IGFBP2's cell motility promoting effect by reducing the pool of free IGFBP2. In conclusion, MMP-9-induced IGFBP2 proteolysis may be regarded as an important post-translational event involved in astrocytoma aggressiveness. These new findings support drug targeting of MMP-9 as an interesting approach in the treatment of astrocytoma.
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Affiliation(s)
- Sandrine Rorive
- Department of Pathology, Erasme University Hospital, Université Libre de Bruxelles, Brussels, Belgium
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8
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Wilczak N, De Keyser J, Chesik D. Targeting Insulin-Like Growth Factor-1 Signaling into the Central Nervous System for Promoting Myelin Repair. Drug Target Insights 2008. [DOI: 10.4137/dti.s362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Affiliation(s)
- Nadine Wilczak
- Department of Neurology, University Medical Center Groningen, the Netherlands
| | - Jacques De Keyser
- Department of Neurology, University Medical Center Groningen, the Netherlands
| | - Daniel Chesik
- Department of Neurology, University Medical Center Groningen, the Netherlands
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9
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Chesik D, Glazenburg L, De Keyser J, Wilczak N. Enhanced proliferation of astrocytes from beta(2)-adrenergic receptor knockout mice is influenced by the IGF system. J Neurochem 2007; 100:1555-64. [PMID: 17348863 DOI: 10.1111/j.1471-4159.2006.04289.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the present study, we investigated the IGF system in neonatal astrocytes derived from mice with a targeted disruption of the beta-2 adrenergic receptor (beta(2)AR). beta(2)AR knockout astrocytes demonstrated higher proliferation rates and increased expression of the astrogliotic marker GFAP, as compared with wild-type cells. beta(2)AR deletion also regulated molecules of the IGF system. Although IGF-1 levels remained unaltered, IGF-2 and type 1 IGF receptor expression was increased in beta(2)AR knockout cells. Furthermore, conditioned medium from knockout astrocytes contained lower levels of IGF binding protein-2 and -4. Our data suggest a deficit of beta(2)AR on astrocytes, as previously reported in multiple sclerosis, may have implications on proliferative status of astrocytes, a feature that might be attributed to regulation of IGF mitogenic actions.
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MESH Headings
- Animals
- Animals, Newborn
- Astrocytes/chemistry
- Astrocytes/drug effects
- Astrocytes/physiology
- Cell Count
- Cell Proliferation/drug effects
- Cells, Cultured
- Cerebral Cortex/cytology
- Culture Media, Conditioned/pharmacology
- Dose-Response Relationship, Drug
- Gene Expression Regulation/genetics
- Insulin-Like Growth Factor Binding Protein 1/metabolism
- Insulin-Like Growth Factor Binding Protein 4/metabolism
- Insulin-Like Growth Factor Binding Protein 4/pharmacology
- Mice
- Mice, Knockout
- RNA, Messenger/biosynthesis
- Receptor, IGF Type 1/metabolism
- Receptor, IGF Type 2/metabolism
- Receptors, Adrenergic, beta-2/deficiency
- Reverse Transcriptase Polymerase Chain Reaction/methods
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Affiliation(s)
- Daniel Chesik
- Department of Neurology, University Medical Center Groningen, Groningen, the Netherlands.
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10
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Borges K, Shaw R, Dingledine R. Gene expression changes after seizure preconditioning in the three major hippocampal cell layers. Neurobiol Dis 2007; 26:66-77. [PMID: 17239605 PMCID: PMC2295285 DOI: 10.1016/j.nbd.2006.12.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2006] [Revised: 10/31/2006] [Accepted: 12/05/2006] [Indexed: 12/23/2022] Open
Abstract
Rodents experience hippocampal damage after status epilepticus (SE) mainly in pyramidal cells while sparing the dentate granule cell layer (DGCL). Hippocampal damage was prevented in rats that had been preconditioned by brief seizures on 2 consecutive days before SE. To identify neuroprotective genes and biochemical pathways changed after preconditioning we compared the effect of preconditioning on gene expression in the CA1 and CA3 pyramidal and DGCLs, harvested by laser capture microscopy. In the DGCL the expression of 632 genes was altered, compared to only 151 and 58 genes in CA1 and CA3 pyramidal cell layers. Most of the differentially expressed genes regulate tissue structure and intra- and extracellular signaling, including neurotransmission. A selective upregulation of energy metabolism transcripts occurred in CA1 pyramidal cells relative to the DGCL. These results reveal a broad transcriptional response of the DGCL to preconditioning, and suggest several mechanisms underlying the neuroprotective effect of preconditioning seizures.
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Affiliation(s)
- Karin Borges
- Department of Pharmacology, School of Medicine, 1510 Clifton Rd, Emory University, Atlanta, GA 30322, USA.
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11
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Chesik D, De Keyser J, Glazenburg L, Wilczak N. Insulin-like growth factor binding proteins: regulation in chronic active plaques in multiple sclerosis and functional analysis of glial cells. Eur J Neurosci 2007; 24:1645-52. [PMID: 17004928 DOI: 10.1111/j.1460-9568.2006.05034.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Studies in experimental allergic encephalomyelitis, an animal model of multiple sclerosis (MS), suggest that astrocyte-secreted insulin-like growth factor binding protein-2 (IGFBP-2) helps target IGF-1 to IGF-1 receptor-expressing oligodendrocytes and promote remyelination. We examined the presence of IGFBPs 1-6 in astrocytes in normal post-mortem human brain tissue and lesions of MS by means of immunohistochemistry. Under normal conditions all six IGFBPs were detected. Compared to controls, hypertrophic astrocytes at the borders of chronic active MS lesions displayed increased immunoreactivity for IGFBP-2 and IGFBP-4. In vitro studies were performed to analyse the effects of IGFBPs on cellular proliferation of neonatal rat glial cells. Treatment of astrocytes with IGF-1 and -2 enhanced proliferation whereas IGFBP-2 and -4 inhibited cellular growth. Interestingly, combined treatment with IGFBP-2 and IGF-1 potentiated effects on cellular proliferation whereas combined treatment with IGFBP-2 and IGF-2 inhibited growth. Unlike IGFBP-2, IGFBP-4 inhibited proliferation in combined treatment with IGF-1. In contrast, combined treatment with IGFBP-2 and IGF-1 resulted in decreased cell survival of oligodendrocyte precursor cells. Our results suggest that the up-regulation of IGFBP-2 in reactive astrocytes in MS lesions may primarily serve to enhance the IGF-1-mediated mitogenic stimulus for astrocytes rather than supporting oligodendrocyte survival.
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Affiliation(s)
- Daniel Chesik
- Department of Neurology, University Medical Center Groningen, Hanzeplein 1, 9713 GZ Groningen, the Netherlands.
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12
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Chesik D, Wilczak N, De Keyser J. The insulin-like growth factor system in multiple sclerosis. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2007; 79:203-26. [PMID: 17531843 DOI: 10.1016/s0074-7742(07)79009-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Multiple sclerosis (MS) is a chronic disorder of the central nervous system characterized by inflammation, demyelination, and axonal degeneration. Present therapeutic strategies for MS reduce inflammation and its destructive consequences, but are not effective in the progressive phase of the disease. There is a need for neuroprotective and restorative therapies in MS. Insulin-like growth factor-1 (IGF-1) is of considerable interest because it is not only a potent neuroprotective trophic factor but also a survival factor for cells of the oligodendrocyte lineage and possesses a potent myelinogenic capacity. However, the IGF system is complex and includes not only IGF-1 and IGF-2 and their receptors but also modulating IGF-binding proteins (IGFBPs), of which six have been identified. This chapter provides an overview of the role of the IGF system in the pathophysiology of MS, relevant findings in preclinical models, and discusses the possible use of IGF-1 as a therapeutic agent for MS.
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Affiliation(s)
- Daniel Chesik
- Department of Neurology, University Medical Center Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
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Chetty A, Manzo N, Waxman AB, Nielsen HC. Modulation of IGF-binding protein-2 and -3 in hyperoxic injury in developing rat lung. Pediatr Res 2005; 58:222-8. [PMID: 16055936 DOI: 10.1203/01.pdr.0000169973.42653.68] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Retinoids play an important role in lung development and repair. We showed that retinoic acid (RA) inhibits O(2)-induced fibroblast proliferation in rat lung explants. IGF-1, which enhances the proliferation of human fetal lung fibroblasts and stimulates collagen production during lung injury, has an important role in the lung injury/repair process. Interactions of IGF-1 with its receptor are modulated by IGF-binding proteins IGFBPs. We hypothesized that RA alters IGFBP-2 and -3 in hyperoxia-exposed neonatal lung and alters collagen production. Neonatal rat lungs were cultured in room air or 95% O(2) and 5% CO(2) for 3 d with or without RA. IGFBP-2 and -3 were measured both in culture medium and in lung tissue. Type I collagen and procollagen propeptide were analyzed in the lung tissue. Hyperoxia induced an increase in type I collagen that was significantly inhibited in the presence of RA. IGFBP-2 and IGFBP-3 in the lungs were decreased in hyperoxia but significantly increased in hyperoxia plus RA. In the culture medium, IGFBP-2 and -3 were not increased with hyperoxia but significantly increased in the presence of RA plus hyperoxia. There was no increase in IGFBP-3 RNA transcript after RA treatment in either room air or O(2) exposure. In conclusion, RA modulates the secreted IGFBP-2 and -3 during O(2) exposure and inhibits the increase in collagen that occurs during lung injury. We speculate that RA protects against O(2)-induced neonatal lung injury through modulation of the IGFBPs.
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Affiliation(s)
- Anne Chetty
- Floating Hospital for Children, New England Medical Center and Tufts Medical School, Boston, Massachusetts 02111, USA.
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