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Neural precursor cells tune striatal connectivity through the release of IGFBPL1. Nat Commun 2022; 13:7579. [PMID: 36482070 PMCID: PMC9731988 DOI: 10.1038/s41467-022-35341-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 11/30/2022] [Indexed: 12/13/2022] Open
Abstract
The adult brain retains over life endogenous neural stem/precursor cells (eNPCs) within the subventricular zone (SVZ). Whether or not these cells exert physiological functions is still unclear. In the present work, we provide evidence that SVZ-eNPCs tune structural, electrophysiological, and behavioural aspects of striatal function via secretion of insulin-like growth factor binding protein-like 1 (IGFBPL1). In mice, selective ablation of SVZ-eNPCs or selective abrogation of IGFBPL1 determined an impairment of striatal medium spiny neuron morphology, a higher failure rate in GABAergic transmission mediated by fast-spiking interneurons, and striatum-related behavioural dysfunctions. We also found IGFBPL1 expression in the human SVZ, foetal and induced-pluripotent stem cell-derived NPCs. Finally, we found a significant correlation between SVZ damage, reduction of striatum volume, and impairment of information processing speed in neurological patients. Our results highlight the physiological role of adult SVZ-eNPCs in supporting cognitive functions by regulating striatal neuronal activity.
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2
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The Role of Inflammation, Hypoxia, and Opioid Receptor Expression in Pain Modulation in Patients Suffering from Obstructive Sleep Apnea. Int J Mol Sci 2022; 23:ijms23169080. [PMID: 36012341 PMCID: PMC9409023 DOI: 10.3390/ijms23169080] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Revised: 08/08/2022] [Accepted: 08/11/2022] [Indexed: 12/18/2022] Open
Abstract
Obstructive sleep apnea (OSA) is a relatively common disease in the general population. Besides its interaction with many comorbidities, it can also interact with potentially painful conditions and modulate its course. The association between OSA and pain modulation has recently been a topic of concern for many scientists. The mechanism underlying OSA-related pain connection has been linked with different pathophysiological changes in OSA and various pain mechanisms. Furthermore, it may cause both chronic and acute pain aggravation as well as potentially influencing the antinociceptive mechanism. Characteristic changes in OSA such as nocturnal hypoxemia, sleep fragmentation, and systemic inflammation are considered to have a curtailing impact on pain perception. Hypoxemia in OSA has been proven to have a significant impact on increased expression of proinflammatory cytokines influencing the hyperalgesic priming of nociceptors. Moreover, hypoxia markers by themselves are hypothesized to modulate intracellular signal transduction in neurons and have an impact on nociceptive sensitization. Pain management in patients with OSA may create problems arousing from alterations in neuropeptide systems and overexpression of opioid receptors in hypoxia conditions, leading to intensification of side effects, e.g., respiratory depression and increased opioid sensitivity for analgesic effects. In this paper, we summarize the current knowledge regarding pain and pain treatment in OSA with a focus on molecular mechanisms leading to nociceptive modulation.
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Horvath A, Quinlan P, Eckerström C, Åberg ND, Wallin A, Svensson J. Low Serum Insulin-like Growth Factor-I Is Associated with Decline in Hippocampal Volume in Stable Mild Cognitive Impairment but not in Alzheimer's Disease. J Alzheimers Dis 2022; 88:1007-1016. [PMID: 35723105 PMCID: PMC9484094 DOI: 10.3233/jad-220292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Background: Serum insulin-like growth factor-I (IGF-I) has shown some association with hippocampal volume in healthy subjects, but this relation has not been investigated in stable mild cognitive impairment (sMCI) or Alzheimer’s disease (AD). Objective: At a single memory clinic, we investigated whether serum IGF-I was associated with baseline magnetic resonance imaging (MRI)-estimated brain volumes and longitudinal alterations, defined as annualized changes, up to 6 years of follow-up. Methods: A prospective study of patients with sMCI (n = 110) and AD (n = 60). Brain regions included the hippocampus and amygdala as well as the temporal, parietal, frontal, and occipital lobes, respectively. Results: Serum IGF-I was statistically similar in sMCI and AD patients (112 versus 123 ng/mL, p = 0.31). In sMCI, serum IGF-I correlated positively with all baseline MRI variables except for the occipital lobe, and there was also a positive correlation between serum IGF-I and the annualized change in hippocampal volume (rs = 0.32, p = 0.02). Furthermore, sMCI patients having serum IGF-I above the median had lower annual loss of hippocampal volume than those with IGF-I below the median (p = 0.02). In contrast, in AD patients, IGF-I did not associate with baseline levels or annualized changes in brain volumes. Conclusion: In sMCI patients, our results suggest that IGF-I exerted neuroprotective effects on the brain, thereby maintaining hippocampal volume. In AD, serum IGF-I did not associate with brain volumes, indicating that IGF-I could not induce neuroprotection in this disease. This supports the notion of IGF-I resistance in AD.
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Affiliation(s)
- Alexandra Horvath
- Department of Internal Medicine, Institute of Medicine, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Patrick Quinlan
- Department of Internal Medicine, Institute of Medicine, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Carl Eckerström
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.,Department of Immunology and Transfusion Medicine, Region Västra Götaland, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - N David Åberg
- Department of Internal Medicine, Institute of Medicine, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.,Department of Acute Medicine and Geriatrics, Region Västra Götaland, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Anders Wallin
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Johan Svensson
- Department of Internal Medicine, Institute of Medicine, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.,Department of Internal Medicine, Region Västra Götaland, Skaraborg Central Hospital, Skövde, Sweden
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4
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Şengül B, Dursun E, Verkhratsky A, Gezen-Ak D. Overexpression of α-Synuclein Reorganises Growth Factor Profile of Human Astrocytes. Mol Neurobiol 2020; 58:184-203. [PMID: 32914394 DOI: 10.1007/s12035-020-02114-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Accepted: 09/01/2020] [Indexed: 12/26/2022]
Abstract
Misfolding and accumulation of aberrant α-synuclein in the brain is associated with the distinct class of neurodegenerative diseases known as α-synucleinopathies, which include Parkinson's disease, dementia with Lewy bodies and multiple system atrophy. Pathological changes in astrocytes contribute to all neurological disorders, and astrocytes are reported to possess α-synuclein inclusions in the context of α-synucleinopathies. Astrocytes are known to express and secrete numerous growth factors, which are fundamental for neuroprotection, synaptic connectivity and brain metabolism; changes in growth factor secretion may contribute to pathobiology of neurological disorders. Here we analysed the effect of α-synuclein overexpression in cultured human astrocytes on growth factor expression and release. For this purpose, the intracellular and secreted levels of 33 growth factors (GFs) and 8 growth factor receptors (GFRs) were analysed in cultured human astrocytes by chemiluminescence-based western/dot blot. Overexpression of human α-synuclein in cultured foetal human astrocytes significantly changes the profile of GF production and secretion. We found that human astrocytes express and secrete FGF2, FGF6, EGF, IGF1, AREG, IGFBP2, IGFBP4, VEGFD, PDGFs, KITLG, PGF, TGFB3 and NTF4. Overexpression of human α-synuclein significantly modified the profile of GF production and secretion, with particularly strong changes in EGF, PDGF, VEGF and their receptors as well as in IGF-related proteins. Bioinformatics analysis revealed possible interactions between α-synuclein and EGFR and GDNF, as well as with three GF receptors, EGFR, CSF1R and PDGFRB.
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Affiliation(s)
- Büşra Şengül
- Brain and Neurodegenerative Disorders Research Laboratories, Department of Medical Biology, Cerrahpasa Faculty of Medicine, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Erdinç Dursun
- Brain and Neurodegenerative Disorders Research Laboratories, Department of Medical Biology, Cerrahpasa Faculty of Medicine, Istanbul University-Cerrahpasa, Istanbul, Turkey.,Department of Neuroscience, Institute of Neurological Sciences, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK. .,Achucarro Centre for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain.
| | - Duygu Gezen-Ak
- Brain and Neurodegenerative Disorders Research Laboratories, Department of Medical Biology, Cerrahpasa Faculty of Medicine, Istanbul University-Cerrahpasa, Istanbul, Turkey.
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5
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Pharaoh G, Owen D, Yeganeh A, Premkumar P, Farley J, Bhaskaran S, Ashpole N, Kinter M, Van Remmen H, Logan S. Disparate Central and Peripheral Effects of Circulating IGF-1 Deficiency on Tissue Mitochondrial Function. Mol Neurobiol 2019; 57:1317-1331. [PMID: 31732912 PMCID: PMC7060968 DOI: 10.1007/s12035-019-01821-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 10/23/2019] [Indexed: 12/15/2022]
Abstract
Age-related decline in circulating levels of insulin-like growth factor (IGF)-1 is associated with reduced cognitive function, neuronal aging, and neurodegeneration. Decreased mitochondrial function along with increased reactive oxygen species (ROS) and accumulation of damaged macromolecules are hallmarks of cellular aging. Based on numerous studies indicating pleiotropic effects of IGF-1 during aging, we compared the central and peripheral effects of circulating IGF-1 deficiency on tissue mitochondrial function using an inducible liver IGF-1 knockout (LID). Circulating levels of IGF-1 (~ 75%) were depleted in adult male Igf1f/f mice via AAV-mediated knockdown of hepatic IGF-1 at 5 months of age. Cognitive function was evaluated at 18 months using the radial arm water maze and glucose and insulin tolerance assessed. Mitochondrial function was analyzed in hippocampus, muscle, and visceral fat tissues using high-resolution respirometry O2K as well as redox status and oxidative stress in the cortex. Peripherally, IGF-1 deficiency did not significantly impact muscle mass or mitochondrial function. Aged LID mice were insulin resistant and exhibited ~ 60% less adipose tissue but increased fat mitochondrial respiration (20%). The effects on fat metabolism were attributed to increases in growth hormone. Centrally, IGF-1 deficiency impaired hippocampal-dependent spatial acquisition as well as reversal learning in male mice. Hippocampal mitochondrial OXPHOS coupling efficiency and cortex ATP levels (~ 50%) were decreased and hippocampal oxidative stress (protein carbonylation and F2-isoprostanes) was increased. These data suggest that IGF-1 is critical for regulating mitochondrial function, redox status, and spatial learning in the central nervous system but has limited impact on peripheral (liver and muscle) metabolism with age. Therefore, IGF-1 deficiency with age may increase sensitivity to damage in the brain and propensity for cognitive deficits. Targeting mitochondrial function in the brain may be an avenue for therapy of age-related impairment of cognitive function. Regulation of mitochondrial function and redox status by IGF-1 is essential to maintain brain function and coordinate hippocampal-dependent spatial learning. While a decline in IGF-1 in the periphery may be beneficial to avert cancer progression, diminished central IGF-1 signaling may mediate, in part, age-related cognitive dysfunction and cognitive pathologies potentially by decreasing mitochondrial function.
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Affiliation(s)
- Gavin Pharaoh
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.,Aging & Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA.,Oklahoma Center for Geroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Daniel Owen
- Oklahoma Center for Geroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Alexander Yeganeh
- Oklahoma Center for Geroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.,Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Pavithra Premkumar
- Aging & Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Julie Farley
- Oklahoma Center for Geroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Shylesh Bhaskaran
- Aging & Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA.,Oklahoma Center for Geroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Nicole Ashpole
- Department of Biomolecular Sciences, University of Mississippi, Oxford, MS, USA
| | - Michael Kinter
- Aging & Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA.,Oklahoma Center for Geroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Holly Van Remmen
- Aging & Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA.,Oklahoma Center for Geroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.,Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Sreemathi Logan
- Oklahoma Center for Geroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA. .,Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA. .,Department of Rehabilitation Sciences, College of Allied Health, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
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6
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Lewitt MS, Boyd GW. The Role of Insulin-Like Growth Factors and Insulin-Like Growth Factor-Binding Proteins in the Nervous System. BIOCHEMISTRY INSIGHTS 2019; 12:1178626419842176. [PMID: 31024217 PMCID: PMC6472167 DOI: 10.1177/1178626419842176] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 03/15/2019] [Indexed: 01/23/2023]
Abstract
The insulin-like growth factors (IGF-I and IGF-II) and their receptors are widely expressed in nervous tissue from early embryonic life. They also cross the blood brain barriers by active transport, and their regulation as endocrine factors therefore differs from other tissues. In brain, IGFs have paracrine and autocrine actions that are modulated by IGF-binding proteins and interact with other growth factor signalling pathways. The IGF system has roles in nervous system development and maintenance. There is substantial evidence for a specific role for this system in some neurodegenerative diseases, and neuroprotective actions make this system an attractive target for new therapeutic approaches. In developing new therapies, interaction with IGF-binding proteins and other growth factor signalling pathways should be considered. This evidence is reviewed, gaps in knowledge are highlighted, and recommendations are made for future research.
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Affiliation(s)
- Moira S Lewitt
- School of Health & Life Sciences, University of the West of Scotland, Paisley, UK
| | - Gary W Boyd
- School of Health & Life Sciences, University of the West of Scotland, Paisley, UK
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7
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Logan S, Jiang C, Yan Y, Inagaki Y, Arzua T, Bai X. Propofol Alters Long Non-Coding RNA Profiles in the Neonatal Mouse Hippocampus: Implication of Novel Mechanisms in Anesthetic-Induced Developmental Neurotoxicity. Cell Physiol Biochem 2018; 49:2496-2510. [PMID: 30261491 DOI: 10.1159/000493875] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Accepted: 09/18/2018] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Propofol induces acute neurotoxicity (e.g., neuroapoptosis) followed by impairment of long-term memory and learning in animals. However, underlying mechanisms remain largely unknown. Long non-coding RNAs (lncRNAs) are found to participate in various pathological processes. We hypothesized that lncRNA profile and the associated signaling pathways were altered, and these changes might be related to the neurotoxicity observed in the neonatal mouse hippocampus following propofol exposure. METHODS In this laboratory experiment, 7-day-old mice were exposed to a subanesthetic dose of propofol for 3 hours, with 4 animals per group. Hippocampal tissues were harvested 3 hours after propofol administration. Neuroapoptosis was analyzed based on caspase 3 activity using a colorimetric assay. A microarray was performed to investigate the profiles of 35,923 lncRNAs and 24,881 messenger RNAs (mRNAs). Representative differentially expressed lncRNAs and mRNAs were validated using reverse transcription quantitative polymerase chain reaction. All mRNAs dysregulated by propofol and the 50 top-ranked, significantly dysregulated lncRNAs were subject to bioinformatics analysis for exploring the potential mechanisms and signaling network of propofol-induced neurotoxicity. RESULTS Propofol induced neuroapoptosis in the hippocampus, with differential expression of 159 lncRNAs and 100 mRNAs (fold change ± 2.0, P< 0.05). Bioinformatics analysis demonstrated that these lncRNAs and their associated mRNAs might participate in neurodegenerative pathways (e.g., calcium handling, apoptosis, autophagy, and synaptogenesis). CONCLUSION This novel report emphasizes that propofol alters profiles of lncRNAs, mRNAs, and their cooperative signaling network, which provides novel insights into molecular mechanisms of anesthetic-induced developmental neurodegeneration and preventive targets against the neurotoxicity.
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Affiliation(s)
- Sarah Logan
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.,Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Congshan Jiang
- Department of Biochemistry and Molecular Biology, School of Basic Medical Science, Xi'an Jiaotong University Health Science Center, Xian, China
| | - Yasheng Yan
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Yasuyoshi Inagaki
- Department of Emergency Medicine, Nayoro City General Hospital, Nayoro, Japan
| | - Thiago Arzua
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.,Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Xiaowen Bai
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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8
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Logan S, Pharaoh GA, Marlin MC, Masser DR, Matsuzaki S, Wronowski B, Yeganeh A, Parks EE, Premkumar P, Farley JA, Owen DB, Humphries KM, Kinter M, Freeman WM, Szweda LI, Van Remmen H, Sonntag WE. Insulin-like growth factor receptor signaling regulates working memory, mitochondrial metabolism, and amyloid-β uptake in astrocytes. Mol Metab 2018; 9:141-155. [PMID: 29398615 PMCID: PMC5870102 DOI: 10.1016/j.molmet.2018.01.013] [Citation(s) in RCA: 107] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 01/11/2018] [Accepted: 01/16/2018] [Indexed: 01/01/2023] Open
Abstract
Objective A decline in mitochondrial function and biogenesis as well as increased reactive oxygen species (ROS) are important determinants of aging. With advancing age, there is a concomitant reduction in circulating levels of insulin-like growth factor-1 (IGF-1) that is closely associated with neuronal aging and neurodegeneration. In this study, we investigated the effect of the decline in IGF-1 signaling with age on astrocyte mitochondrial metabolism and astrocyte function and its association with learning and memory. Methods Learning and memory was assessed using the radial arm water maze in young and old mice as well as tamoxifen-inducible astrocyte-specific knockout of IGFR (GFAP-CreTAM/igfrf/f). The impact of IGF-1 signaling on mitochondrial function was evaluated using primary astrocyte cultures from igfrf/f mice using AAV-Cre mediated knockdown using Oroboros respirometry and Seahorse assays. Results Our results indicate that a reduction in IGF-1 receptor (IGFR) expression with age is associated with decline in hippocampal-dependent learning and increased gliosis. Astrocyte-specific knockout of IGFR also induced impairments in working memory. Using primary astrocyte cultures, we show that reducing IGF-1 signaling via a 30–50% reduction IGFR expression, comparable to the physiological changes in IGF-1 that occur with age, significantly impaired ATP synthesis. IGFR deficient astrocytes also displayed altered mitochondrial structure and function and increased mitochondrial ROS production associated with the induction of an antioxidant response. However, IGFR deficient astrocytes were more sensitive to H2O2-induced cytotoxicity. Moreover, IGFR deficient astrocytes also showed significantly impaired glucose and Aβ uptake, both critical functions of astrocytes in the brain. Conclusions Regulation of astrocytic mitochondrial function and redox status by IGF-1 is essential to maintain astrocytic function and coordinate hippocampal-dependent spatial learning. Age-related astrocytic dysfunction caused by diminished IGF-1 signaling may contribute to the pathogenesis of Alzheimer's disease and other age-associated cognitive pathologies. Altered mitochondrial structure and function with IGFR deficiency in astrocytes is proposed. Increased reactive oxygen species production and susceptibility to peroxide induced cytotoxicity. Decreased Aβ uptake and impairment in spatial working memory.
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Affiliation(s)
- Sreemathi Logan
- Reynold's Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, USA.
| | - Gavin A Pharaoh
- Department of Physiology, University of Oklahoma Health Sciences Center, USA; Aging & Metabolism Research Program, Oklahoma Medical Research Foundation, USA
| | - M Caleb Marlin
- Graduate College, University of Oklahoma Health Sciences Center, USA
| | - Dustin R Masser
- Reynold's Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, USA; Department of Physiology, University of Oklahoma Health Sciences Center, USA
| | - Satoshi Matsuzaki
- Aging & Metabolism Research Program, Oklahoma Medical Research Foundation, USA; Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, USA
| | - Benjamin Wronowski
- Reynold's Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, USA; Department of Physiology, University of Oklahoma Health Sciences Center, USA
| | - Alexander Yeganeh
- Reynold's Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, USA; Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, USA
| | - Eileen E Parks
- Reynold's Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, USA; Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, USA
| | - Pavithra Premkumar
- Aging & Metabolism Research Program, Oklahoma Medical Research Foundation, USA
| | - Julie A Farley
- Reynold's Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, USA
| | - Daniel B Owen
- Reynold's Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, USA
| | - Kenneth M Humphries
- Aging & Metabolism Research Program, Oklahoma Medical Research Foundation, USA; Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, USA
| | - Michael Kinter
- Aging & Metabolism Research Program, Oklahoma Medical Research Foundation, USA
| | - Willard M Freeman
- Reynold's Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, USA; Department of Physiology, University of Oklahoma Health Sciences Center, USA; Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, USA
| | - Luke I Szweda
- Aging & Metabolism Research Program, Oklahoma Medical Research Foundation, USA; Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, USA
| | - Holly Van Remmen
- Department of Physiology, University of Oklahoma Health Sciences Center, USA; Aging & Metabolism Research Program, Oklahoma Medical Research Foundation, USA; Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, USA
| | - William E Sonntag
- Reynold's Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, USA; Department of Physiology, University of Oklahoma Health Sciences Center, USA; Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, USA
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9
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Abstract
The retina is part of the central nervous system and both the retina as well as the brain can suffer from severe damage after very preterm birth. Retinopathy of prematurity is one of the major causes of blindness in these children and brain neuronal impairments including cognitive defects, cerebral palsy and intraventricular hemorrhage (IVH) are also complications of very preterm birth. Insulin-like growth factor 1 (IGF-1) acts to promote proliferation, maturation, growth and survival of neural cells. Low levels of circulating IGF-1 are associated with ROP and defects in the IGF-1 gene are associated with CNS disorders including learning deficits and brain growth restriction. Treatment of preterm infants with recombinant IGF-1 may potentially prevent ROP and CNS disorders. This review compares the role of IGF-1 in ROP and CNS disorders. A recent phase 2 study showed a positive effect of IGF-1 on the severity of IVH but no effect on ROP. A phase 3 trial is planned.
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Affiliation(s)
- Raffael Liegl
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Chatarina Löfqvist
- Department of Ophthalmology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Ann Hellström
- Department of Ophthalmology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Lois E H Smith
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
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10
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Oji S, Nicolussi EM, Kaufmann N, Zeka B, Schanda K, Fujihara K, Illes Z, Dahle C, Reindl M, Lassmann H, Bradl M. Experimental Neuromyelitis Optica Induces a Type I Interferon Signature in the Spinal Cord. PLoS One 2016; 11:e0151244. [PMID: 26990978 PMCID: PMC4798752 DOI: 10.1371/journal.pone.0151244] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 02/25/2016] [Indexed: 12/15/2022] Open
Abstract
Neuromyelitis optica (NMO) is an acute inflammatory disease of the central nervous system (CNS) which predominantly affects spinal cord and optic nerves. Most patients harbor pathogenic autoantibodies, the so-called NMO-IgGs, which are directed against the water channel aquaporin 4 (AQP4) on astrocytes. When these antibodies gain access to the CNS, they mediate astrocyte destruction by complement-dependent and by antibody-dependent cellular cytotoxicity. In contrast to multiple sclerosis (MS) patients who benefit from therapies involving type I interferons (I-IFN), NMO patients typically do not profit from such treatments. How is I-IFN involved in NMO pathogenesis? To address this question, we made gene expression profiles of spinal cords from Lewis rat models of experimental neuromyelitis optica (ENMO) and experimental autoimmune encephalomyelitis (EAE). We found an upregulation of I-IFN signature genes in EAE spinal cords, and a further upregulation of these genes in ENMO. To learn whether the local I-IFN signature is harmful or beneficial, we induced ENMO by transfer of CNS antigen-specific T cells and NMO-IgG, and treated the animals with I-IFN at the very onset of clinical symptoms, when the blood-brain barrier was open. With this treatment regimen, we could amplify possible effects of the I-IFN induced genes on the transmigration of infiltrating cells through the blood brain barrier, and on lesion formation and expansion, but could avoid effects of I-IFN on the differentiation of pathogenic T and B cells in the lymph nodes. We observed that I-IFN treated ENMO rats had spinal cord lesions with fewer T cells, macrophages/activated microglia and activated neutrophils, and less astrocyte damage than their vehicle treated counterparts, suggesting beneficial effects of I-IFN.
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Affiliation(s)
- Satoru Oji
- Department of Neuroimmunology, Center for Brain Research, Medical University Vienna, Vienna, Austria
| | - Eva-Maria Nicolussi
- Department of Neuroimmunology, Center for Brain Research, Medical University Vienna, Vienna, Austria
| | - Nathalie Kaufmann
- Department of Neuroimmunology, Center for Brain Research, Medical University Vienna, Vienna, Austria
| | - Bleranda Zeka
- Department of Neuroimmunology, Center for Brain Research, Medical University Vienna, Vienna, Austria
| | - Kathrin Schanda
- Clinical Department of Neurology, Innsbruck Medical University, Innsbruck, Austria
| | - Kazuo Fujihara
- Departments of Multiple Sclerosis Therapeutics and Neurology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Zsolt Illes
- Department of Neurology, University of Southern Denmark, Odense, Denmark
| | - Charlotte Dahle
- Department of Clinical Immunology and Transfusion Medicine and Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Markus Reindl
- Clinical Department of Neurology, Innsbruck Medical University, Innsbruck, Austria
| | - Hans Lassmann
- Department of Neuroimmunology, Center for Brain Research, Medical University Vienna, Vienna, Austria
| | - Monika Bradl
- Department of Neuroimmunology, Center for Brain Research, Medical University Vienna, Vienna, Austria
- * E-mail:
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11
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Role and Importance of IGF-1 in Traumatic Brain Injuries. BIOMED RESEARCH INTERNATIONAL 2015; 2015:736104. [PMID: 26417600 PMCID: PMC4568328 DOI: 10.1155/2015/736104] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 12/24/2014] [Indexed: 01/02/2023]
Abstract
It is increasingly affirmed that most of the long-term consequences of TBI are due to molecular and cellular changes occurring during the acute phase of the injury and which may, afterwards, persist or progress. Understanding how to prevent secondary damage and improve outcome in trauma patients, has been always a target of scientific interest. Plans of studies focused their attention on the posttraumatic neuroendocrine dysfunction in order to achieve a correlation between hormone blood level and TBI outcomes. The somatotropic axis (GH and IGF-1) seems to be the most affected, with different alterations between the acute and late phases. IGF-1 plays an important role in brain growth and development, and it is related to repair responses to damage for both the central and peripheral nervous system. The IGF-1 blood levels result prone to decrease during both the early and late phases after TBI. Despite this, experimental studies on animals have shown that the CNS responds to the injury upregulating the expression of IGF-1; thus it appears to be related to the secondary mechanisms of response to posttraumatic damage. We review the mechanisms involving IGF-1 in TBI, analyzing how its expression and metabolism may affect prognosis and outcome in head trauma patients.
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Astrocyte physiopathology: At the crossroads of intercellular networking, inflammation and cell death. Prog Neurobiol 2015; 130:86-120. [PMID: 25930681 DOI: 10.1016/j.pneurobio.2015.04.003] [Citation(s) in RCA: 139] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 04/15/2015] [Accepted: 04/20/2015] [Indexed: 12/11/2022]
Abstract
Recent breakthroughs in neuroscience have led to the awareness that we should revise our traditional mode of thinking and studying the CNS, i.e. by isolating the privileged network of "intelligent" synaptic contacts. We may instead need to contemplate all the variegate communications occurring between the different neural cell types, and centrally involving the astrocytes. Basically, it appears that a single astrocyte should be considered as a core that receives and integrates information from thousands of synapses, other glial cells and the blood vessels. In turn, it generates complex outputs that control the neural circuitry and coordinate it with the local microcirculation. Astrocytes thus emerge as the possible fulcrum of the functional homeostasis of the healthy CNS. Yet, evidence indicates that the bridging properties of the astrocytes can change in parallel with, or as a result of, the morphological, biochemical and functional alterations these cells undergo upon injury or disease. As a consequence, they have the potential to transform from supportive friends and interactive partners for neurons into noxious foes. In this review, we summarize the currently available knowledge on the contribution of astrocytes to the functioning of the CNS and what goes wrong in various pathological conditions, with a particular focus on Amyotrophic Lateral Sclerosis, Alzheimer's Disease and ischemia. The observations described convincingly demonstrate that the development and progression of several neurological disorders involve the de-regulation of a finely tuned interplay between multiple cell populations. Thus, it seems that a better understanding of the mechanisms governing the integrated communication and detrimental responses of the astrocytes as well as their impact towards the homeostasis and performance of the CNS is fundamental to open novel therapeutic perspectives.
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Brahmkhatri VP, Prasanna C, Atreya HS. Insulin-like growth factor system in cancer: novel targeted therapies. BIOMED RESEARCH INTERNATIONAL 2015; 2015:538019. [PMID: 25866791 PMCID: PMC4383470 DOI: 10.1155/2015/538019] [Citation(s) in RCA: 171] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 10/13/2014] [Accepted: 10/20/2014] [Indexed: 12/15/2022]
Abstract
Insulin-like growth factors (IGFs) are essential for growth and survival that suppress apoptosis and promote cell cycle progression, angiogenesis, and metastatic activities in various cancers. The IGFs actions are mediated through the IGF-1 receptor that is involved in cell transformation induced by tumour. These effects depend on the bioavailability of IGFs, which is regulated by IGF binding proteins (IGFBPs). We describe here the role of the IGF system in cancer, proposing new strategies targeting this system. We have attempted to expand the general viewpoint on IGF-1R, its inhibitors, potential limitations of IGF-1R, antibodies and tyrosine kinase inhibitors, and IGFBP actions. This review discusses the emerging view that blocking IGF via IGFBP is a better option than blocking IGF receptors. This can lead to the development of novel cancer therapies.
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Affiliation(s)
| | - Chinmayi Prasanna
- NMR Research Centre, Indian Institute of Science, Bangalore 560012, India
| | - Hanudatta S. Atreya
- NMR Research Centre, Indian Institute of Science, Bangalore 560012, India
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
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Yan H, Mitschelen M, Toth P, Ashpole NM, Farley JA, Hodges EL, Warrington JP, Han S, Fung KM, Csiszar A, Ungvari Z, Sonntag WE. Endothelin-1-induced focal cerebral ischemia in the growth hormone/IGF-1 deficient Lewis Dwarf rat. J Gerontol A Biol Sci Med Sci 2014; 69:1353-62. [PMID: 25098324 DOI: 10.1093/gerona/glu118] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Aging is a major risk factor for cerebrovascular disease. Growth hormone (GH) and its anabolic mediator, insulin-like growth factor (IGF)-1, decrease with advancing age and this decline has been shown to promote vascular dysfunction. In addition, lower GH/IGF-1 levels are associated with higher stroke mortality in humans. These results suggest that decreased GH/IGF-1 level is an important factor in increased risk of cerebrovascular diseases. This study was designed to assess whether GH/IGF-1-deficiency influences the outcome of cerebral ischemia. We found that endothelin-1-induced middle cerebral artery occlusion resulted in a modest but nonsignificant decrease in cerebral infarct size in GH/IGF-1 deficient dw/dw rats compared with control heterozygous littermates and dw/dw rats with early-life GH treatment. Expression of endothelin receptors and endothelin-1-induced constriction of the middle cerebral arteries were similar in the three experimental groups. Interestingly, dw/dw rats exhibited reduced brain edema and less astrocytic infiltration compared with their heterozygous littermates and this effect was reversed by GH-treatment. Because reactive astrocytes are critical for the regulation of poststroke inflammatory processes, maintenance of the blood-brain barrier and neural repair, further studies are warranted to determine the long-term functional consequences of decreased astrocytic activation in GH/IGF-1 deficient animals after cerebral ischemia.
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Affiliation(s)
- Han Yan
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City
| | - Matthew Mitschelen
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City
| | - Peter Toth
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City
| | - Nicole M Ashpole
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City
| | - Julie A Farley
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City
| | - Erik L Hodges
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City
| | - Junie P Warrington
- Present address: Department of Physiology & Biophysics, University of Mississippi Medical Center, Jackson, MS 39216
| | - Song Han
- Present address: Human Oncology and Pathogenesis Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065
| | - Kar-Ming Fung
- Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City
| | - Anna Csiszar
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City
| | - Zoltan Ungvari
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City
| | - William E Sonntag
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City.
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Sonntag WE, Deak F, Ashpole N, Toth P, Csiszar A, Freeman W, Ungvari Z. Insulin-like growth factor-1 in CNS and cerebrovascular aging. Front Aging Neurosci 2013; 5:27. [PMID: 23847531 PMCID: PMC3698444 DOI: 10.3389/fnagi.2013.00027] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 06/14/2013] [Indexed: 12/26/2022] Open
Abstract
Insulin-like growth factor-1 (IGF-1) is an important anabolic hormone that decreases with age. In the past two decades, extensive research has determined that the reduction in IGF-1 is an important component of the age-related decline in cognitive function in multiple species including humans. Deficiency in circulating IGF-1 results in impairment in processing speed and deficiencies in both spatial and working memory. Replacement of IGF-1 or factors that increase IGF-1 to old animals and humans reverses many of these cognitive deficits. Despite the overwhelming evidence for IGF-1 as an important neurotrophic agent, the specific mechanisms through which IGF-1 acts have remained elusive. Recent evidence indicates that IGF-1 is both produced by and has important actions on the cerebrovasculature as well as neurons and glia. Nevertheless, the specific regulation and actions of brain- and vascular-derived IGF-1 is poorly understood. The diverse effects of IGF-1 discovered thus far reveal a complex endocrine and paracrine system essential for integrating many of the functions necessary for brain health. Identification of the mechanisms of IGF-1 actions will undoubtedly provide critical insight into regulation of brain function in general and the causes of cognitive decline with age.
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Affiliation(s)
- William E Sonntag
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center Oklahoma City, OK, USA
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Yan Y, Li X, Kover K, Clements M, Ye P. CREB participates in the IGF-I-stimulation cyclin D1 transcription. Dev Neurobiol 2013; 73:559-70. [DOI: 10.1002/dneu.22080] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 02/04/2013] [Accepted: 02/21/2013] [Indexed: 01/13/2023]
Affiliation(s)
- Yun Yan
- Department of Pediatrics; Division of Endocrinology; University of North Carolina at Chapel Hill; Chapel Hill; North Carolina
| | - Xiaoyu Li
- Department of Pediatrics, Children's Mercy Hospitals & Clinics; University of Missouri-Kansas City; Kansas City; Missouri
| | - Karen Kover
- Department of Pediatrics, Children's Mercy Hospitals & Clinics; University of Missouri-Kansas City; Kansas City; Missouri
| | - Mark Clements
- Department of Pediatrics, Children's Mercy Hospitals & Clinics; University of Missouri-Kansas City; Kansas City; Missouri
| | - Ping Ye
- Department of Pediatrics; Division of Endocrinology; University of North Carolina at Chapel Hill; Chapel Hill; North Carolina
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O’Kusky J, Ye P. Neurodevelopmental effects of insulin-like growth factor signaling. Front Neuroendocrinol 2012; 33:230-51. [PMID: 22710100 PMCID: PMC3677055 DOI: 10.1016/j.yfrne.2012.06.002] [Citation(s) in RCA: 139] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 05/09/2012] [Accepted: 06/07/2012] [Indexed: 11/28/2022]
Abstract
Insulin-like growth factor (IGF) signaling greatly impacts the development and growth of the central nervous system (CNS). IGF-I and IGF-II, two ligands of the IGF system, exert a wide variety of actions both during development and in adulthood, promoting the survival and proliferation of neural cells. The IGFs also influence the growth and maturation of neural cells, augmenting dendritic growth and spine formation, axon outgrowth, synaptogenesis, and myelination. Specific IGF actions, however, likely depend on cell type, developmental stage, and local microenvironmental milieu within the brain. Emerging research also indicates that alterations in IGF signaling likely contribute to the pathogenesis of some neurological disorders. This review summarizes experimental studies and shed light on the critical roles of IGF signaling, as well as its mechanisms, during CNS development.
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Affiliation(s)
- John O’Kusky
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada V5Z 1M9
| | - Ping Ye
- Department of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States
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Signalling through the type 1 insulin-like growth factor receptor (IGF1R) interacts with canonical Wnt signalling to promote neural proliferation in developing brain. ASN Neuro 2012; 4:AN20120009. [PMID: 22625652 PMCID: PMC3392751 DOI: 10.1042/an20120009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Signalling through the IGF1R [type 1 IGF (insulin-like growth factor) receptor] and canonical Wnt signalling are two signalling pathways that play critical roles in regulating neural cell generation and growth. To determine whether the signalling through the IGF1R can interact with the canonical Wnt signalling pathway in neural cells in vivo, we studied mutant mice with altered IGF signalling. We found that in mice with blunted IGF1R expression specifically in nestin-expressing neural cells (IGF1RNestin−KO mice) the abundance of neural β-catenin was significantly reduced. Blunting IGF1R expression also markedly decreased: (i) the activity of a LacZ (β-galactosidase) reporter transgene that responds to Wnt nuclear signalling (LacZTCF reporter transgene) and (ii) the number of proliferating neural precursors. In contrast, overexpressing IGF-I (insulin-like growth factor I) in brain markedly increased the activity of the LacZTCF reporter transgene. Consistently, IGF-I treatment also markedly increased the activity of the LacZTCF reporter transgene in embryonic neuron cultures that are derived from LacZTCF Tg (transgenic) mice. Importantly, increasing the abundance of β-catenin in IGF1RNestin−KO embryonic brains by suppressing the activity of GSK3β (glycogen synthase kinase-3β) significantly alleviated the phenotypic changes induced by IGF1R deficiency. These phenotypic changes includes: (i) retarded brain growth, (ii) reduced precursor proliferation and (iii) decreased neuronal number. Our current data, consistent with our previous study of cultured oligodendrocytes, strongly support the concept that IGF signalling interacts with canonical Wnt signalling in the developing brain to promote neural proliferation. The interaction of IGF and canonical Wnt signalling plays an important role in normal brain development by promoting neural precursor proliferation.
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IGFBP-3 Inhibits the Proliferation of Neural Progenitor Cells. Neurochem Res 2010; 36:406-11. [DOI: 10.1007/s11064-010-0349-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2010] [Indexed: 12/26/2022]
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Ye P, Hu Q, Liu H, Yan Y, D'ercole AJ. beta-catenin mediates insulin-like growth factor-I actions to promote cyclin D1 mRNA expression, cell proliferation and survival in oligodendroglial cultures. Glia 2010; 58:1031-41. [PMID: 20235220 PMCID: PMC2917840 DOI: 10.1002/glia.20984] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
By promoting cell proliferation, survival and maturation insulin-like growth factor (IGF)-I is essential to the normal growth and development of the central nervous system. It is clear that IGF-I actions are primarily mediated by the type I IGF receptor (IGF1R), and that phosphoinositide 3 (PI3)-Akt kinases and MAP kinases signal many of IGF-I-IGF1R actions in neural cells, including oligodendrocyte lineage cells. The precise downstream targets of these signaling pathways, however, remain to be defined. We studied oligodendroglial cells to determine whether beta-catenin, a molecule that is a downstream target of glycogen synthase kinase-3beta (GSK3beta) and plays a key role in the Wnt canonical signaling pathway, mediates IGF-I actions. We found that IGF-I increases beta-catenin protein abundance within an hour after IGF-I-induced phosphorylation of Akt and GSK3beta. Inhibiting the PI3-Akt pathway suppressed IGF-I-induced increases in beta-catenin and cyclin D1 mRNA, while suppression of GSK3beta activity simulated IGF-I actions. Knocking-down beta-catenin mRNA by RNA interference suppressed IGF-I-stimulated increases in the abundance of cyclin D1 mRNA, cell proliferation, and cell survival. Our data suggest that beta-catenin is an important downstream molecule in the PI3-Akt-GSK3beta pathway, and as such it mediates IGF-I upregulation of cyclin D1 mRNA and promotion of cell proliferation and survival in oligodendroglial cells.
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Affiliation(s)
- Ping Ye
- Department of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7039, USA.
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Liu W, Ye P, O'Kusky JR, D'Ercole AJ. Type 1 insulin-like growth factor receptor signaling is essential for the development of the hippocampal formation and dentate gyrus. J Neurosci Res 2010; 87:2821-32. [PMID: 19437543 DOI: 10.1002/jnr.22129] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Type 1 insulin-like growth factor receptor (IGF1R) signaling in neuronal development was studied in mutant mice with blunted igf1r gene expression in nestin-expressing neuronal precursors. At birth [postnatal (P) day 0] brain weights were reduced to 37% and 56% of controls in mice homozygous (nes-igf1r(-/-)) and heterozygous (nes-igf1r(-/Wt)) for the null mutation, respectively, and this brain growth retardation persisted postnatally. Stereological analysis demonstrated that the volumes of the hippocampal formation, CA fields 1-3, dentate gyrus (DG), and DG granule cell layer (GCL) were decreased by 44-54% at P0 and further by 65-69% at P90 in nes-igf1r(-/Wt) mice. In nes-igf1r(-/-) mice, volumes were 29-31% of controls at P0 and, in the two mice that survived to P90, 6-19% of controls, although the hilus could not be identified. Neuron density did not differ among the mice at any age studied; therefore, decreased volumes were due to reduced cell number. In postnatal nes-igf1r(-/Wt) mice, the percentage of apoptotic cells, as judged by activated caspase-3 immunostaining, was increased by 3.5-5.3-fold. The total number of proliferating DG progenitors (labeled by BrdU incorporation and Ki67 staining) was reduced by approximately 50%, but the percentage of these cells was similar to the percentages in littermate controls. These findings suggest that 1) the postnatal reduction in DG size is due predominantly to cell death, pointing to the importance of the IGF1R in regulating postnatal apoptosis, 2) surviving DG progenitors remain capable of proliferation despite reduced IGF1R expression, and 3) IGF1R signaling is necessary for normal embryonic brain development.
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Affiliation(s)
- Wen Liu
- Department of Pediatrics, Division of Endocrinology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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Astrocytes in the damaged brain: molecular and cellular insights into their reactive response and healing potential. Biochem Pharmacol 2009; 79:77-89. [PMID: 19765548 DOI: 10.1016/j.bcp.2009.09.014] [Citation(s) in RCA: 238] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Revised: 09/08/2009] [Accepted: 09/10/2009] [Indexed: 12/29/2022]
Abstract
Long considered merely a trophic and mechanical support to neurons, astrocytes have progressively taken the center stage as their ability to react to acute and chronic neurodegenerative situations became increasingly clear. Reactive astrogliosis starts when trigger molecules produced at the injury site drive astrocytes to leave their quiescent state and become activated. Distinctive morphological and biochemical features characterize this process (cell hypertrophy, upregulation of intermediate filaments, and increased cell proliferation). Moreover, reactive astrocytes migrate towards the injured area to constitute the glial scar, and release factors mediating the tissue inflammatory response and remodeling after lesion. A novel view of astrogliosis derives from the finding that subsets of reactive astrocytes can recapitulate stem cell/progenitor features after damage, fostering the concept of astroglia as a promising target for reparative therapies. But which biochemical/signaling pathways modulate astrogliosis with respect to both the time after injury and the type of damage? Are reactive astrocytes overall beneficial or detrimental for neuroprotection and tissue regeneration? This debate has been animating this research field for several years now, and an integrated view on the results obtained and the possible future perspectives is needed. With this Commentary article we have attempted to answer the above-mentioned questions by reviewing the current knowledge on the molecular mechanisms controlling and sustaining the reaction of astroglia to injury and its stem cell-like properties. Moreover, the cellular/molecular mechanisms supporting the detrimental or beneficial features of astrogliosis have been scrutinized to gain insights on possible pharmacological approaches to enhance astrocyte neuroprotective activities.
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Yuen JSP, Macaulay VM. Targeting the type 1 insulin-like growth factor receptor as a treatment for cancer. Expert Opin Ther Targets 2008; 12:589-603. [PMID: 18410242 DOI: 10.1517/14728222.12.5.589] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND The type 1 insulin-like growth factor receptor (IGF1R) plays a critical role in transformation, invasion and apoptosis protection, and is an attractive cancer treatment target. OBJECTIVE To review IGF1R antibodies and kinase inhibitors that are in preclinical and clinical development, and to discuss questions that will influence the success of this approach in clinical practice. METHODS This review is drawn from published literature, meeting abstracts and online resources. RESULTS/CONCLUSION IGF1R blockade is generally well tolerated although it can induce hyperglycaemia. Single-agent activity has been documented in Ewing's sarcoma but not thus far in common solid tumours. Key issues include identification of factors that influence sensitivity to IGF1R blockade, and how most effectively to combine IGF1R inhibitors with other treatments.
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Affiliation(s)
- John S P Yuen
- Weatherall Institute of Molecular Medicine, University of Oxford, IGF Group, Molecular Oncology Laboratories, Headley Way, Headington, Oxford OX3 9DS, UK
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Zhang J, Moats-Staats BM, Ye P, D’Ercole AJ. Expression of insulin-like growth factor system genes during the early postnatal neurogenesis in the mouse hippocampus. J Neurosci Res 2007; 85:1618-27. [PMID: 17455296 PMCID: PMC2302789 DOI: 10.1002/jnr.21289] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Insulin-like growth factor-1 (IGF-1) is essential to hippocampal neurogenesis and the neuronal response to hypoxia/ischemia injury. IGF (IGF-1 and -2) signaling is mediated primarily by the type 1 IGF receptor (IGF-1R) and modulated by six high-affinity binding proteins (IGFBP) and the type 2 IGF receptor (IGF-2R), collectively termed IGF system proteins. Defining the precise cells that express each is essential to understanding their roles. With the exception of IGFBP-1, we found that mouse hippocampus expresses mRNA for each of these proteins during the first 2 weeks of postnatal life. Compared to postnatal day 14 (P14), mRNA abundance at P5 was higher for IGF-1, IGFBP-2, -3, and -5 (by 71%, 108%, 100%, and 98%, respectively), lower for IGF-2, IGF-2R, and IGFBP-6 (by 65%, 78%, and 44%, respectively), and unchanged for IGF-1R and IGFBP-4. Using laser capture microdissection (LCM), we found that granule neurons and pyramidal neurons exhibited identical patterns of expression of IGF-1, IGF-1R, IGF-2R, IGFBP-2, and -4, but did not express other IGF system genes. We then compared IGF system expression in mature granule neurons and their progenitors. Progenitors exhibited higher mRNA levels of IGF-1 and IGF-1R (by 130% and 86%, respectively), lower levels of IGF-2R (by 72%), and similar levels of IGFBP-4. Our data support a role for IGF in hippocampal neurogenesis and provide evidence that IGF actions are regulated within a defined in vivo milieu.
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Affiliation(s)
| | | | | | - A. Joseph D’Ercole
- * Correspondence to: A. Joseph D’Ercole, Department of Pediatrics, CB 7039, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7039. E-mail:
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Hansen-Pupp I, Hellström-Westas L, Cilio CM, Andersson S, Fellman V, Ley D. Inflammation at birth and the insulin-like growth factor system in very preterm infants. Acta Paediatr 2007; 96:830-6. [PMID: 17465986 DOI: 10.1111/j.1651-2227.2007.00276.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Foetal inflammation is associated with an increased risk of brain damage in preterm infants whereas IGF-I is essential for cerebral development and exhibits anti-apoptotic properties. AIM To assess levels of IGF-I and IGF binding proteins at very preterm birth and to evaluate their relationship with foetal pro-inflammation and cerebral damage. METHODS Levels of IGF-I, IGF binding protein 3 (IGFBP-3), high- (hp) and low-phosphorylated (lp) IGFBP-1 in cord blood and neonatal blood at 72 h after delivery were analysed in relation to levels of cytokines and cerebral damage as detected by ultrasound in 74 inborn infants [mean gestational age (GA) 27.1 weeks]. Evaluation was performed separately according to birth weight for GA. RESULTS In cord blood of infants appropriate for gestational age (AGA) higher levels of IL-6 and IL-8 were associated with lower IGF-I (r =-0.38, p = 0.008 and r =-0.36, p = 0.014). Higher levels of IL-6, IL-8 and TNF-alpha were associated with both higher levels of lpIGFBP-1 (r = 0.54, p < 0.001, r = 0.50, p < 0.001 and r = 0.13, p = 0.012, respectively) and hpIGFBP-1 (r = 0.55, p < 0.001, r = 0.45, p = 0.002 and r = 0.32, p = 0.026, respectively). Infants with intraventricular haemorrhage grade III (n = 5) had higher levels of lp/hpIGFBP-1 in cord blood (p = 0.001 and 0.002, respectively). CONCLUSION Pro-inflammation at birth is associated with changes in the IGF-system. This may be of importance for development of brain damage in preterm infants.
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Affiliation(s)
- I Hansen-Pupp
- Institution of Clinical Sciences and Department of Pediatrics, Lund University, Lund, Sweden.
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Zeger M, Popken G, Zhang J, Xuan S, Lu QR, Schwab MH, Nave KA, Rowitch D, D’Ercole AJ, Ye P. Insulin-like growth factor type 1 receptor signaling in the cells of oligodendrocyte lineage is required for normal in vivo oligodendrocyte development and myelination. Glia 2007; 55:400-11. [PMID: 17186502 PMCID: PMC1774584 DOI: 10.1002/glia.20469] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Insulin-like growth factor-I (IGF-I) has been shown to be a potent agent in promoting the growth and differentiation of oligodendrocyte precursors, and in stimulating myelination during development and following injury. To definitively determine whether IGF-I acts directly on the cells of oligodendrocyte lineage, we generated lines of mice in which the type 1 IGF receptor gene (igf1r) was conditionally ablated either in Olig1 or proteolipid protein expressing cells (termed IGF1R(pre-oligo-ko) and IGF1R(oligo-ko) mice, respectively). Compared with wild type mice, IGF1R(pre-oligo-ko) mice had a decreased volume (by 35-55%) and cell number (by 54-70%) in the corpus callosum (CC) and anterior commissure at 2 and 6 weeks of age, respectively. IGF1R(oligo-ko) mice by 25 weeks of age also showed reductions, albeit less marked, in CC volume and cell number. Unlike astrocytes, the percentage of NG2(+) oligodendrocyte precursors was decreased by approximately 13% in 2-week-old IGF1R(pre-oligo-ko) mice, while the percentage of CC1(+) mature oligodendrocytes was decreased by approximately 24% in 6-week-old IGF1R(pre-oligo-ko) mice and approximately 25% in 25-week-old IGF1R(oligo-ko) mice. The reduction in these cells is apparently a result of decreased proliferation and increased apoptosis. These results indicate that IGF-I directly affects oligodendrocytes and myelination in vivo via IGF1R, and that IGF1R signaling in the cells of oligodendrocyte lineage is required for normal oligodendrocyte development and myelination. These data also provide a fundamental basis for developing strategies with the potential to target IGF-IGF1R signaling pathways in oligodendrocyte lineage cells for the treatment of demyelinating disorders.
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Affiliation(s)
- Martha Zeger
- Dept of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Greg Popken
- Dept of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Jihui Zhang
- Dept of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Shouhong Xuan
- Dept of Genetics and Development, Columbia University, New York, New York
| | - Q. Richard Lu
- Dana-Farber Cancer Institute, Harvard University, Boston, MA
| | - Markus H. Schwab
- Dept of Neurogenetics, Max Planck Institute of Experimental Medicine, Germany
| | - Klaus-Armin Nave
- Dept of Neurogenetics, Max Planck Institute of Experimental Medicine, Germany
| | - David Rowitch
- Dana-Farber Cancer Institute, Harvard University, Boston, MA
| | - A. Joseph D’Ercole
- Dept of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Ping Ye
- Dept of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, NC
- Correspondence should be addressed to Dr. Ping Ye, Department of Pediatrics, CB# 7039, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7039, Tel: (919) 966-4435, Fax: (919) 966-2423, E-mail:
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27
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Torres Aleman I. Role of Insulin-Like Growth Factors in Neuronal Plasticity and Neuroprotection. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2005; 567:243-58. [PMID: 16370142 DOI: 10.1007/0-387-26274-1_10] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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28
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Popken GJ, Dechert-Zeger M, Ye P, D'Ercole AJ. Brain Development. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2005; 567:187-220. [PMID: 16372399 DOI: 10.1007/0-387-26274-1_8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Affiliation(s)
- Gregory J Popken
- Division Pediatric Endocrinology, Department of Pediatrics, University of North Carolina at Chapel Hill, NC 27599-7039, USA
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29
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Russo VC, Gluckman PD, Feldman EL, Werther GA. The insulin-like growth factor system and its pleiotropic functions in brain. Endocr Rev 2005; 26:916-43. [PMID: 16131630 DOI: 10.1210/er.2004-0024] [Citation(s) in RCA: 355] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In recent years, much interest has been devoted to defining the role of the IGF system in the nervous system. The ubiquitous IGFs, their cell membrane receptors, and their carrier binding proteins, the IGFBPs, are expressed early in the development of the nervous system and are therefore considered to play a key role in these processes. In vitro studies have demonstrated that the IGF system promotes differentiation and proliferation and sustains survival, preventing apoptosis of neuronal and brain derived cells. Furthermore, studies of transgenic mice overexpressing components of the IGF system or mice with disruptions of the same genes have clearly shown that the IGF system plays a key role in vivo.
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Affiliation(s)
- V C Russo
- Centre for Hormone Research, Murdoch Children's Research Institute, Royal Children's Hospital, Flemington Road, Parkville, Victoria 3052, Australia.
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30
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Kastenbauer S, Angele B, Sporer B, Pfister HW, Koedel U. Patterns of protein expression in infectious meningitis: a cerebrospinal fluid protein array analysis. J Neuroimmunol 2005; 164:134-9. [PMID: 15885808 DOI: 10.1016/j.jneuroim.2005.03.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2004] [Accepted: 03/21/2005] [Indexed: 01/17/2023]
Abstract
Seventy-nine cytokines, chemokines, and growth factors were measured by protein array analysis in the cerebrospinal fluid of patients with meningitis and controls. Several factors were found to be regulated, which have not been studied in the CNS before, e.g., macrophage inflammatory protein-1delta (CCL15) and neutrophil-activating peptide-2 (CXCL7). In pneumococcal meningitis, other new observations were an increase of macrophage migration inhibitory factor, monocyte chemoattractant protein-2 (CCL8), pulmonary and activation-regulated chemokine (CCL18), and macrophage inflammatory protein-3alpha (CCL20), and a sustained upregulation of several growth factors. In viral meningitis, new findings were an elevation of CCL8, thrombopoietin, and vascular endothelial growth factor.
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Affiliation(s)
- Stefan Kastenbauer
- Department of Neurology, Klinikum Grosshadern, Ludwig-Maximilians-University, Marchioninistr. 15, 81377 Munich, Germany.
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31
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Bunn RC, King WD, Winkler MK, Fowlkes JL. Early developmental changes in IGF-I, IGF-II, IGF binding protein-1, and IGF binding protein-3 concentration in the cerebrospinal fluid of children. Pediatr Res 2005; 58:89-93. [PMID: 15774848 DOI: 10.1203/01.pdr.0000156369.62787.96] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
IGF-I and IGF-II are ubiquitously expressed growth factors that have profound effects on the growth and differentiation of many cell types and tissues, including cells of the CNS. In biologic fluids, most IGFs are bound to one of six IGF binding proteins (IGFBPs 1-6). Increasing evidence strongly supports a role for IGF-I in CNS development, as it promotes neuronal proliferation and survival. However, little is known about IGF-I and its homolog IGF-II and their carrier proteins, IGFBPs, during the neonatal period in which brain size increases dramatically, myelination takes place, and neurons show limited capacity to proliferate. Herein, we have determined the concentrations of IGF-I, IGF-II, IGFBP-1, and IGFBP-3 in cerebral spinal fluid (CSF) samples that were collected from children who were 1 wk to 18 y of age. The concentrations of IGF-I, IGFBP-1, and IGFBP-3 in CSF from children <6 mo of age were significantly higher than in older children, whereas IGF-II was higher in the older group. This is in contrast to what is observed in the peripheral circulation, where IGF-I and IGFBP-3 are low at birth and rise rapidly during the first year, reaching peak levels during puberty. Higher concentrations of IGF-I, IGFBP-1, and IGFBP-3 in the CSF of very young children suggest that these proteins might participate in the active processes of myelination and synapse formation in the developing nervous system. We propose that IGF-I and certain IGFBPs are likely necessary for normal CNS development during critical stages of neonatal brain growth and development.
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Affiliation(s)
- R Clay Bunn
- Arkansas Children's Hospital Research Institute, and Department of Pediatrics, University of Arkansas for Medical Sciences, 1120 Marshall Street, Little Rock, AR 72202, USA.
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32
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Wolf E, Schneider MR, Zhou R, Fisch TM, Herbach N, Dahlhoff M, Wanke R, Hoeflich A. Functional consequences of IGFBP excess-lessons from transgenic mice. Pediatr Nephrol 2005; 20:269-78. [PMID: 15602658 DOI: 10.1007/s00467-004-1657-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2004] [Revised: 07/26/2004] [Accepted: 07/26/2004] [Indexed: 11/29/2022]
Abstract
The functions of insulin-like growth factor-binding proteins (IGFBPs) have been studied extensively in vitro, revealing IGF-dependent and also IGF-independent effects on cell growth, differentiation, and survival. In contrast, the biological relevance of IGFBPs in vivo is only partially understood. In the past decade, mouse models lacking or overexpressing specific IGFBPs have been generated by transgenic technology. Phenotypic analysis revealed features that are common for most IGFBPs (growth inhibition), but also effects that appear to be specific for some but not all IGFBPs, such as disturbed glucose homeostasis (IGFBP-1 and -3) or impaired fertility (IGFBP-1, -5, and -6). Future systematic comparison of IGFBP functions in transgenic mice will be facilitated by targeted insertion of IGFBP expression vectors and by standardized phenotype assessment. Furthermore, analysis of IGFBP expression in growth-selected mouse lines or pedigrees segregating for growth phenotypes will be important to understand the roles of IGFBPs in multigenic growth regulation.
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Affiliation(s)
- Eckhard Wolf
- Institute of Molecular Animal Breeding and Biotechnology/Gene Center, Munich, Germany.
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33
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Richards LJ, Plachez C, Ren T. Mechanisms regulating the development of the corpus callosum and its agenesis in mouse and human. Clin Genet 2005; 66:276-89. [PMID: 15355427 DOI: 10.1111/j.1399-0004.2004.00354.x] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The development of the corpus callosum depends on a large number of different cellular and molecular mechanisms. These include the formation of midline glial populations, and the expression of specific molecules required to guide callosal axons as they cross the midline. An additional mechanism used by callosal axons from neurons in the neocortex is to grow within the pathway formed by pioneering axons derived from neurons in the cingulate cortex. Data in humans and in mice suggest the possibility that different mechanisms may regulate the development of the corpus callosum across its rostrocaudal and dorsoventral axes. The complex developmental processes required for formation of the corpus callosum may provide some insight into why such a large number of human congenital syndromes are associated with agenesis of this structure.
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Affiliation(s)
- L J Richards
- The University of Maryland School of Medicine, Department of Anatomy and Neurobiology and Programs in Neuroscience and Membrane Biology, Baltimore, MD 21201, USA.
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34
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Ye P, Popken GJ, Kemper A, McCarthy K, Popko B, D'Ercole AJ. Astrocyte-specific overexpression of insulin-like growth factor-I promotes brain overgrowth and glial fibrillary acidic protein expression. J Neurosci Res 2005; 78:472-84. [PMID: 15468174 DOI: 10.1002/jnr.20288] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Insulin-like growth factor-I (IGF-I) is widely expressed in the central nervous system (CNS). Whereas during normal development IGF-I is expressed predominantly by neurons and to a much lesser degree by glial cells, its expression in astrocytes, and often in microglia, is increased during and/or after variety of CNS injuries. Recently we have generated a new line of IGF-I Tg mice, called IGF-I(Ast/Tet-Off) Tg mice, in which IGF-I transgene is expressed specifically in astrocytes and is tightly controlled by the tetracycline analog doxycycline. In this study we examined whether IGF-I derived from astrocytes is capable of promoting neural cell growth during development. When the IGF-I transgene is allowed to be expressed, IGF-I(Ast/Tet-Off) Tg mice exhibit markedly increases in 1) brain weight; 2) brain DNA and protein abundance; and 3) number of neurons, oligodendrocytes, and astrocytes, as well as myelination, findings similar to those observed in our other lines of Tg mice that express IGF-I transgene predominantly in neurons. Unlike Tg mice with neuron-specific IGF-I expression, which manifest marked increases in the concentrations of oligodendrocyte/myelin-specific proteins, however, IGF-I(Ast/Tet-Off) Tg mice exhibit an increase in the concentration of glial fibrillary acidic protein, an astrocyte-specific protein. Furthermore, when transgene expression is blunted, brain overgrowth in IGF-I(Ast/Tet-Off) Tg mice ceases. Our data indicate that astrocyte-derived IGF-I is capable of promoting neural cells growth in vivo. Our data also suggest that IGF-I's actions in CNS depend in part on the location of its expression and cellular microenvironment and that continuous presence of IGF-I expression is necessary for brain overgrowth.
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Affiliation(s)
- Ping Ye
- Department of Pediatrics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
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35
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Crespel A, Baldy-Moulinier M, Lerner Natoli M. [Neurogenesis in the adult brain: the demise of a dogma and the advent of new treatments]. Rev Neurol (Paris) 2004; 160:1150-8. [PMID: 15602360 DOI: 10.1016/s0035-3787(04)71159-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Since the early sixties, many concepts concerning neurogenesis have been progressively ruled out. Proof of the persistence of a physiological neurogenesis in adult mammals, including humans, raised the concept of a unique precursor cell giving birth to neurons and glial cells. According to this concept, a real continuum between neuroepithelial cells, radial glia and astrocytes exists from the embryonic period to adult age and generates both neurons and glial cells. Different factors, either secreted in situ or transported by blood, can influence this physiological neurogenesis process. The targets and role of newborn neurons are not clearly understood. In pathological conditions (ischemia, epilepsy, lesions), the physiological neurogenesis process is enhanced; however the significance of this neurogenesis excess (beneficial or deleterious) is not completely known. Advances in understanding the regulation of neurogenesis in these different conditions represent hopes of new therapeutic procedures, not only by improving the control of differentiation and survival of transplanted stem cells, but also by the possibility of modifying the processes of "endogenous neurogenesis".
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Affiliation(s)
- A Crespel
- Service Explorations Neurologiques et Epileptologie, Hôpital Gui de Chauliac, Montpellier.
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36
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Abstract
Insulin-like growth factors (IGFs) provide essential signals for the control of embryonic and postnatal development in vertebrate species. In mammals, IGFs act through and are regulated by a system of receptors, binding proteins, and related proteases. In each of the many tissues dependent on this family of growth factors, this system generates a complex interaction specific to the tissue concerned. Studies carried out over the last decade, mostly with transgenic and gene knockout mouse models, have demonstrated considerable variety in the cell type-specific and developmental stage-specific functions of IGF signals. Brain, muscle, bone, cartilage, pancreas, ovary, skin, and fat tissue have been identified as major in vivo targets for IGFs. Concentrating on several of these organ systems, we review here phenotypic analyses of mice with genetically modified IGF systems. Much progress has also been made in understanding the specific intracellular signaling cascades initiated by the binding of circulating IGFs to their cognate receptor. We also summarize the most relevant aspects of this research. Considerable efforts are currently focused on deciphering the functional specificities of intracellular pathways, particularly the molecular mechanisms by which cells distinguish growth-stimulating insulin-like signals from metabolic insulin signals. Finally, there is a growing body of evidence implicating IGF signaling in lifespan control, and it has recently been shown that this function has been conserved throughout evolution. Very rapid progress in this domain seems to indicate that longevity may be subject to IGF-dependent neuroendocrine regulation and that certain periods of the life cycle may be particularly important in the determination of individual lifespan.
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Affiliation(s)
- Joëlle Dupont
- Institut National de la Recherche Agronomique, Centre National de la Recherche Scientifique, UMR 6073, Nouzilly, France
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37
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Salih DAM, Tripathi G, Holding C, Szestak TAM, Gonzalez MI, Carter EJ, Cobb LJ, Eisemann JE, Pell JM. Insulin-like growth factor-binding protein 5 (Igfbp5) compromises survival, growth, muscle development, and fertility in mice. Proc Natl Acad Sci U S A 2004; 101:4314-9. [PMID: 15010534 PMCID: PMC384738 DOI: 10.1073/pnas.0400230101] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2003] [Indexed: 12/27/2022] Open
Abstract
The insulin-like growth factors (IGFs) are essential for development; bioavailable IGF is tightly regulated by six related IGF-binding proteins (IGFBPs). Igfbp5 is the most conserved and is developmentally up-regulated in key lineages and pathologies; in vitro studies suggest that IGFBP-5 functions independently of IGF interaction. Genetic ablation of individual Igfbps has yielded limited phenotypes because of substantial compensation by remaining family members. Therefore, to reveal Igfbp5 actions in vivo, we generated lines of transgenic mice that ubiquitously overexpressed Igfbp5 from early development. Significantly increased neonatal mortality, reduced female fertility, whole-body growth inhibition, and retarded muscle development were observed in Igfbp5-overexpressing mice. The magnitude of the response in individual transgenic lines was positively correlated with Igfbp5 expression. Circulating IGFBP-5 concentrations increased a maximum of only 4-fold, total and free IGF-I concentrations increased up to 2-fold, and IGFBP-5 was detected in high M(r) complexes; however, no detectable decrease in the proportion of free IGF-I was observed. Thus, despite only modest changes in IGF and IGFBP concentrations, the Igfbp5-overexpressing mice displayed a phenotype more extreme than that observed for other Igfbp genetic models. Although growth retardation was obvious prenatally, maximal inhibition occurred postnatally before the onset of growth hormone-dependent growth, regardless of Igfbp5 expression level, revealing a period of sensitivity to IGFBP-5 during this important stage of tissue programming.
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Affiliation(s)
- Dervis A M Salih
- Signalling Programme, The Babraham Institute, Cambridge CB2 4AT, United Kingdom
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38
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Varela-Nieto I, de la Rosa EJ, Valenciano AI, León Y. Cell death in the nervous system: lessons from insulin and insulin-like growth factors. Mol Neurobiol 2003; 28:23-50. [PMID: 14514984 DOI: 10.1385/mn:28:1:23] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2002] [Accepted: 02/28/2003] [Indexed: 12/11/2022]
Abstract
Programmed cell death is an essential process for proper neural development. Cell death, with its similar regulatory and executory mechanisms, also contributes to the origin or progression of many or even all neurodegenerative diseases. An understanding of the mechanisms that regulate cell death during neural development may provide new targets and tools to prevent neurodegeneration. Many studies that have focused mainly on insulin-like growth factor-I (IGF-I), have shown that insulin-related growth factors are widely expressed in the developing and adult nervous system, and positively modulate a number of processes during neural development, as well as in adult neuronal and glial physiology. These factors also show neuroprotective effects following neural damage. Although some specific actions have been demonstrated to be anti-apoptotic, we propose that a broad neuroprotective role is the foundation for many of the observed functions of the insulin-related growth factors, whose therapeutical potential for nervous system disorders may be greater than currently accepted.
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Affiliation(s)
- Isabel Varela-Nieto
- Instituto de Investigaciones Biomédicas "Alberto Sols," Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid (CSIC-UAM), Arturo Duperier 4, E-28029 Madrid, Spain.
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39
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O'Kusky JR, Ye P, D'Ercole AJ. Increased expression of insulin-like growth factor I augments the progressive phase of synaptogenesis without preventing synapse elimination in the hypoglossal nucleus. J Comp Neurol 2003; 464:382-91. [PMID: 12900931 DOI: 10.1002/cne.10794] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The in vivo actions of insulin-like growth factor I (IGF-I) on synaptogenesis in the hypoglossal nucleus were investigated in transgenic mice that overexpress IGF-I in the brain postnatally and in normal nontransgenic littermate controls. In a previous study using these mice, we found that IGF-I increases the total volume of the hypoglossal nucleus by increasing the volume of neuropil rather than by increasing total neuron number; therefore, the progressive and regressive phases of synaptogenesis could be evaluated without the confounding effects of altered neuron number. The volume of the hypoglossal nucleus was significantly increased by 28% to 59% in transgenic mice after postnatal day (P) 7, whereas the total number of hypoglossal neurons did not differ significantly from controls. The numerical density of neurons was significantly decreased by 21% to 38% after P7, and the density of myelinated axons was significantly increased by 19%. Although the numerical density of synapses did not differ between groups at any age, the total number of synapses in transgenic mice was increased by 42% to 52% after P14. Total synapse number in controls increased from P7 (7.9 million) to peak values at P21 (36.0 million), followed by a significant decrease (33%) at P130 (24.2 million). In transgenic mice, total synapses increased from 8.2 million on P7 to 51.1 million on P21, followed by a significant decrease (28%) to 36.7 million at P130. Our results demonstrated that IGF-I can stimulate a persistent increase in the number of hypoglossal synapses, thereby augmenting the progressive phase of synaptogenesis without preventing synapse elimination during the regressive phase.
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Affiliation(s)
- John Robert O'Kusky
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia V5Z 1M9, Canada.
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40
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Richards LJ. Axonal pathfinding mechanisms at the cortical midline and in the development of the corpus callosum. Braz J Med Biol Res 2002; 35:1431-9. [PMID: 12436186 DOI: 10.1590/s0100-879x2002001200004] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The corpus callosum is a large fiber tract that connects neurons in the right and left cerebral hemispheres. Agenesis of the corpus callosum (ACC) is associated with a large number of human syndromes but little is known about why ACC occurs. In most cases of ACC, callosal axons are able to grow toward the midline but are unable to cross it, continuing to grow into large swirls of axons known as Probst bundles. This phenotype suggests that in some cases ACC may be due to defects in axonal guidance at the midline. General guidance mechanisms that influence the development of axons include chemoattraction and chemorepulsion, presented by either membrane-bound or diffusible molecules. These molecules are not only expressed by the final target but by intermediate targets along the pathway, and by pioneering axons that act as guides for later arriving axons. Midline glial populations are important intermediate targets for commissural axons in the spinal cord and brain, including the corpus callosum. The role of midline glial populations and pioneering axons in the formation of the corpus callosum are discussed. Finally the differential guidance of the ipsilaterally projecting perforating pathway and the contralaterally projecting corpus callosum is addressed. Development of the corpus callosum involves the coordination of a number of different guidance mechanisms and the probable involvement of a large number of molecules.
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Affiliation(s)
- L J Richards
- Department of Anatomy and Neurobiology, and the Program in Neuroscience, School of Medicine, University of Maryland, Baltimore, MD 21201, USA.
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41
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Abstract
In addition to their roles in IGF transport, the six IGF-binding proteins (IGFBPs) regulate cell activity in various ways. By sequestering IGFs away from the type I IGF receptor, they may inhibit mitogenesis, differentiation, survival, and other IGF-stimulated events. IGFBP proteolysis can reverse this inhibition or generate IGFBP fragments with novel bioactivity. Alternatively, IGFBP interaction with cell or matrix components may concentrate IGFs near their receptor, enhancing IGF activity. IGF receptor-independent IGFBP actions are also increasingly recognized. IGFBP-1 interacts with alpha(5)beta(1) integrin, influencing cell adhesion and migration. IGFBP-2, -3, -5, and -6 have heparin-binding domains and can bind glycosaminoglycans. IGFBP-3 and -5 have carboxyl-terminal basic motifs incorporating heparin-binding and additional basic residues that interact with the cell surface and matrix, the nuclear transporter importin-beta, and other proteins. Serine/threonine kinase receptors are proposed for IGFBP-3 and -5, but their signaling functions are poorly understood. Other cell surface IGFBP-interacting proteins are uncharacterized as functional receptors. However, IGFBP-3 binds and modulates the retinoid X receptor-alpha, interacts with TGFbeta signaling through Smad proteins, and influences other signaling pathways. These interactions can modulate cell cycle and apoptosis. Because IGFBPs regulate cell functions by diverse mechanisms, manipulation of IGFBP-regulated pathways is speculated to offer therapeutic opportunities in cancer and other diseases.
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Affiliation(s)
- Sue M Firth
- Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, St Leonards, New South Wales 2065, Australia
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42
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Abstract
Increasing evidence indicates that insulin-like growth factor-I (IGF-I) has an important role in oligodendrocyte development. In this study, we examined myelination during postnatal development in IGF-I knock-out (KO) mice by assessing myelin staining, the expression of myelin basic protein (MBP) and proteolipid protein (PLP), two major myelin-specific proteins, and the number of oligodendrocytes and their precursors. For comparison, we also measured the expression of median subunit of the neuron-specific intermediate filament, M-neurofilament (M-NF), to obtain an index of the effects of IGF-I deficiency on neurons. We found that myelin staining, MBP and PLP expression, and the percentage of oligodendrocytes and their precursors are significantly reduced in all brain regions of developing IGF-I KO mice but are similar to controls in adult IGF-I KO mice. In contrast, the abundance of M-NF was decreased in both the developing and adult brain of IGF-I KO mice. We also found that IGF-II protein abundance is increased in the brains of IGF-I KO mice. Our data indicate, therefore, that myelination during early development is altered in the absence of IGF-I by mechanisms that involve a reduction in oligodendrocyte proliferation and development. Although neuronal actions cannot be excluded in the myelin normalization, the reduced axonal growth suggested by the reduced M-NF expression makes a role for neuronal factors less compelling. These data suggest that IGF-I plays a significant role in myelination during normal early development and that IGF-II can compensate in part for IGF-I actions on myelination.
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43
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Kühl NM, De Keyser J, De Vries H, Hoekstra D. Insulin-like growth factor binding proteins-1 and -2 differentially inhibit rat oligodendrocyte precursor cell survival and differentiation in vitro. J Neurosci Res 2002; 69:207-16. [PMID: 12111802 DOI: 10.1002/jnr.10293] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Insulin-like growth factor-1 (IGF-1) is a growth and survival factor for oligodendrocyte lineage cells and induces myelination. Its actions are modulated by IGF binding proteins (IGFBPs) that are present in the extracellular fluids or on the cell surface. Additionally, IGFBPs are also known to exert actions that are independent of IGF-1. We studied whether IGF-binding proteins (IGFBPs)-1 and -2 modulate rat oligodendrocyte precursor (O2A) cell survival and differentiation in vitro both in the absence and presence of exogenously added IGF-1. The data reveal that IGFBP-1 and -2 reduced O2A cell survival in the absence and presence of exogenously added IGF-1. The effects of IGFBP-1 on cell survival in the presence of exogenously added IGF-1 were IGF-1-dependent, whereas IGFBP-2 displayed both IGF-1-dependent and IGF-1-independent effects. Furthermore, IGFBP-1 and -2 inhibited O2A cell differentiation in the presence of IGF-1 as reflected by decreased expression levels of two myelin proteins, CNPase (2',3'-cyclic nucleotide 3'-phosphohydrolase) and MAG (myelin associated glycoprotein). Analysis of medium samples revealed that O2A cells do not secrete proteases that degrade these IGFBPs. Taken together the data show that IGFBP-1 and -2 are negative effectors of oligodendrocyte survival and differentiation. Accordingly, the role of IGFBPs should be explicitly taken into account when investigating IGF-1 effects on oligodendrocytes, especially in the context of therapeutic purposes.
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Affiliation(s)
- Nicole M Kühl
- Department Membrane Cell Biology, University Groningen, Groningen, The Netherlands
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44
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D'Ercole AJ, Ye P, O'Kusky JR. Mutant mouse models of insulin-like growth factor actions in the central nervous system. Neuropeptides 2002; 36:209-20. [PMID: 12359511 DOI: 10.1054/npep.2002.0893] [Citation(s) in RCA: 157] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Insulin-like growth factor-I (IGF-I) and its cognate receptor, the type 1 IGF receptor (IGF1R), as well as high-affinity IGF binding proteins (IGFBP) that modulate IGF-I actions, are expressed throughout the course of brain development. These observations, taken together with studies in cultured neural cells demonstrating a variety of IGF-I growth-promoting activities, provide a strong argument for IGF-I having a central role in the growth and development of the CNS. This report reviews studies of brain development in mutant mice with alterations of IGF-I expression or action. Transgenic (Tg) mice overexpressing IGF-I postnatally exhibit brain overgrowth characterized by increased neuron and oligodendrocyte number, as well as marked increases in myelination. Mutant mice with ablated IGF-I and IGF1R expression, as well as those with overexpression of IGFBPs capable of inhibiting IGF actions, exhibit brain growth retardation with a variety of growth deficits. These studies confirm a role for IGF-I in neural development, and indicate that IGF-I stimulates neurogenesis and synaptogenesis, facilitates oligodendrocyte development, promotes neuron and oligodendrocyte survival, and stimulates myelination. Evidence from experiments in these mouse models also indicates that IGF-I has a role in recovery from neural injury.
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Affiliation(s)
- A Joseph D'Ercole
- Department of Pediatrics, Division of Endocrinology, University of North Carolina at Chapel Hill, North Carolina 27599-7220, USA.
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Longhi L, Saatman KE, Raghupathi R, Laurer HL, Lenzlinger PM, Riess P, Neugebauer E, Trojanowski JQ, Lee VM, Grady MS, Graham DI, McIntosh TK. A review and rationale for the use of genetically engineered animals in the study of traumatic brain injury. J Cereb Blood Flow Metab 2001; 21:1241-58. [PMID: 11702040 DOI: 10.1097/00004647-200111000-00001] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The mechanisms underlying secondary cell death after traumatic brain injury (TBI) are poorly understood. Animal models of TBI recapitulate many clinical and pathologic aspects of human head injury, and the development of genetically engineered animals has offered the opportunity to investigate the specific molecular and cellular mechanisms associated with cell dysfunction and death after TBI, allowing for the evaluation of specific cause-effect relations and mechanistic hypotheses. This article represents a compendium of the current literature using genetically engineered mice in studies designed to better understand the posttraumatic inflammatory response, the mechanisms underlying DNA damage, repair, and cell death, and the link between TBI and neurodegenerative diseases.
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Affiliation(s)
- L Longhi
- Department of Neurosurgery, University of Pennsylvania and Veterans Administration Medical Center, Philadelphia, Pennsylvania 19104, USA
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Insulin-like growth factor-I promotes neurogenesis and synaptogenesis in the hippocampal dentate gyrus during postnatal development. J Neurosci 2001. [PMID: 11069951 DOI: 10.1523/jneurosci.20-22-08435.2000] [Citation(s) in RCA: 252] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The in vivo actions of insulin-like growth factor-I (IGF-I) on the growth and development of the hippocampal dentate gyrus were investigated in transgenic mice that overexpress IGF-I postnatally in the brain and in normal nontransgenic littermate controls. Stereological analyses of the dentate gyrus were performed by light and electron microscopy on days 7, 14, 21, 28, 35, and 130 to determine postnatal changes in the numerical density and total number of neurons and synapses. The volumes of both the granule cell layer and the molecular layer of the dentate gyrus were significantly increased by 27-69% in transgenic mice after day 7, with the greatest relative increases occurring by day 35. Although the numerical density of neurons in the granule cell layer did not differ significantly between transgenic and control mice at any age studied, the total number of neurons was significantly greater in transgenic mice by 29-61% beginning on day 14. The total number of synapses in the molecular layer was significantly increased by 42-105% in transgenic mice from day 14 to day 130. A transient increase in the synapse-to-neuron ratio was found in transgenic mice at postnatal days 28 and 35 but not at day 130. This finding indicates a disproportionate increase in synaptogenesis, exceeding that expected for the observed increase in neuron number. Our results demonstrate that IGF-I overexpression produces persistent increases in the total number of neurons and synapses in the dentate gyrus, indicating that IGF-I promotes both neurogenesis and synaptogenesis in the developing hippocampus in vivo.
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Abstract
Although brain injury induced by undernutrition during early life is well described, the mechanisms that mediate the effects of undernutrition on brain development are not known. IGF-I plays an important role in the stimulation of postnatal somatic and brain growth. We have shown that IGF-I overexpression in brain ameliorates the effects of undernutrition on early postnatal brain growth, and thus, we postulated that alterations in IGF-I expression or action mediate the pathogenesis of malnutrition-induced brain injury. To begin to address this issue we evaluated the influence of undernutrition on brain IGF-I expression during early postnatal development in mice. Undernutrition was induced in mice by separating half of the pups in each litter from their lactating dams for a defined period each day. Pups were killed at postnatal day (P) 7, P14, P21, and P28. The changes in IGF-I mRNA were quantified by ribonuclease protection assay. At P7 IGF-I mRNA abundance in undernourished animals was increased in cerebral cortex (223% of controls), but decreased in diencephalon (36% of controls). At P14, IGF-I mRNA abundance was increased in diencephalon (230% of controls). Although there were no other statistically significant alterations of IGF-I mRNA in undernourished mice, IGF-I abundance in the cerebral cortex appeared increased at P14 (142% of controls), and in cerebellum it was consistently but modestly decreased (78 and 59% of controls) from P7 to P21, respectively. We conclude that nutrition regulates murine brain IGF-I expression in a developmentally specific fashion that is dependent on the region of expression. Importantly, the influence of undernutrition on IGF-I expression is markedly different in the brain than in liver, where nutritional deficiency profoundly decreases IGF-I expression. We speculate that the relative preservation of or increases in regional brain IGF-I expression explain, at least in part, the well-known finding that undernutrition during early postnatal development has less marked growth-retarding effects on the brain than it does on the soma.
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Affiliation(s)
- A Calikoglu
- Department of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7220, USA
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Ye P, Lee KH, D'Ercole AJ. Insulin-like growth factor-I (IGF-I) protects myelination from undernutritional insult: studies of transgenic mice overexpressing IGF-I in brain. J Neurosci Res 2000; 62:700-8. [PMID: 11104508 DOI: 10.1002/1097-4547(20001201)62:5<700::aid-jnr9>3.0.co;2-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Using insulin-like growth factor-I (IGF-I)-overexpressing transgenic (Tg) mice as a model, we have shown that IGF-I promotes myelination by increasing the number of oligodendrocytes and stimulating the expression of myelin-specific protein genes. In the present study, we investigated whether IGF-I protects myelination from undernutritional insult in Tg mice. Mice were undernourished beginning from postnatal (P) day 1, a time coincident with the onset of transgene expression, and sacrificed at P20. Consistently with our previous studies, brain weights of undernourished non-Tg control mice were decreased by approximately 18%. Brain weights of undernourished IGF-I Tg mice, however, were the same as those of well-fed control mice and much greater than those of undernourished control mice. The expression of two major myelin proteins [myelin basic protein (MBP) and proteolipid protein (PLP)] in cerebral cortex (CTX) and hippocampus (HIP) was decreased by 73-92% in undernourished control mice, as judged by Northern and Western blot hybridization. The abundances of MBP and PLP mRNAs and proteins, however, were decreased by only 40-70% in undernourished IGF-I Tg mice. To assess the number of oligodendrocytes and their precursors, antibodies specific for carbonic anhydrase II (CAII; an oligodendrocyte marker) and NG2 (a precursor marker) were used. Compared to their well-fed counterparts, undernourished control mice exhibited 17-30% decreases in the number of oligodendrocytes and their precursors in CTX and corpus callosum (CC), whereas well-fed IGF-I Tg mice had 21-35% increases in CTX and CC. Undernourished IGF-I Tg mice exhibited cell numbers similar to those of well-fed control mice. These data indicate that IGF-I protects myelination from undernutrition damage during development.
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Affiliation(s)
- P Ye
- Department of Pediatrics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7220, USA.
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Blasko I, Veerhuis R, Stampfer-Kountchev M, Saurwein-Teissl M, Eikelenboom P, Grubeck-Loebenstein B. Costimulatory effects of interferon-gamma and interleukin-1beta or tumor necrosis factor alpha on the synthesis of Abeta1-40 and Abeta1-42 by human astrocytes. Neurobiol Dis 2000; 7:682-9. [PMID: 11114266 DOI: 10.1006/nbdi.2000.0321] [Citation(s) in RCA: 184] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chronic inflammation and astrocytosis are characteristic histopathological features of Alzheimer's Disease (AD). Astrocytes are one of the predominant cell types in the brain. In AD they are activated and produce inflammatory components such as complement components, acute phase proteins, and cytokines. In this study we analyzed the effect of cytokines on the production of amyloid beta (Abeta) in the astrocytoma cell line U373 and in primary human astrocytes isolated postmortem from healthy aged persons as well as from patients with AD. Astrocytes did not produce Abeta in the absence of stimuli or following stimulation with IL-1beta, TNFalpha, IL-6, and TGF-beta1. Neither did combinations of TNFalpha and IL-1beta, IL-6 or TGF-beta1, or the coadministration of IFNgamma and IL-6 or TGF-beta1 induce Abeta production. In contrast, pronounced production of Abeta1-40 and Abeta1-42 was observed when primary astrocytes or astrocytoma cells were stimulated with combinations of IFNgamma and TNFalpha or IFNgamma and IL-1beta. Induction of Abeta production was accompanied by decreased glycosylation of APP as well as by increased secretion of APPsbeta. Our results suggest that astrocytes may be an important source of Abeta in the presence of certain combinations of inflammatory cytokines. IFNgamma in combination with TNFalpha or IL-1beta seems to trigger Abeta production by supporting beta-secretase cleavage of the immature APP molecule.
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Affiliation(s)
- I Blasko
- Institute for Biomedical Aging Research of the Austrian Academy of Sciences, Innsbruck, Austria
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