1
|
Xu F, Takahashi H, Tanaka Y, Ichinose S, Niwa S, Wicklund MP, Hirokawa N. KIF1Bβ mutations detected in hereditary neuropathy impair IGF1R transport and axon growth. J Cell Biol 2018; 217:3480-3496. [PMID: 30126838 PMCID: PMC6168269 DOI: 10.1083/jcb.201801085] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Revised: 05/31/2018] [Accepted: 07/05/2018] [Indexed: 02/07/2023] Open
Abstract
Uncovering the mechanistic link between kinesin motors and neuropathy, Xu et al. identify functional KIF1Bβ mutations in human hereditary neuropathy to analyze them in mouse models. They propose that KIF1Bβ transports IGF1R and facilitates axonal outgrowth. Both of these effects are significantly affected by the clinical mutations. KIF1Bβ is a kinesin-3 family anterograde motor protein essential for neuronal development, viability, and function. KIF1Bβ mutations have previously been reported in a limited number of pedigrees of Charcot-Marie-Tooth disease type 2A (CMT2A) neuropathy. However, the gene responsible for CMT2A is still controversial, and the mechanism of pathogenesis remains elusive. In this study, we show that the receptor tyrosine kinase IGF1R is a new direct binding partner of KIF1Bβ, and its binding and transport is specifically impaired by the Y1087C mutation of KIF1Bβ, which we detected in hereditary neuropathic patients. The axonal outgrowth and IGF-I signaling of Kif1b−/− neurons were significantly impaired, consistent with decreased surface IGF1R expression. The complementary capacity of KIF1Bβ-Y1087C of these phenotypes was significantly impaired, but the binding capacity to synaptic vesicle precursors was not affected. These data have supported the relevance of KIF1Bβ in IGF1R transport, which may give new clue to the neuropathic pathogenesis.
Collapse
Affiliation(s)
- Fang Xu
- Department of Cell Biology and Anatomy, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Hironori Takahashi
- Department of Cell Biology and Anatomy, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Yosuke Tanaka
- Department of Cell Biology and Anatomy, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Sotaro Ichinose
- Department of Cell Biology and Anatomy, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Shinsuke Niwa
- Department of Cell Biology and Anatomy, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | | | - Nobutaka Hirokawa
- Department of Cell Biology and Anatomy, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan .,Center of Excellence in Genome Medicine Research, King Abdulaziz University, Jeddah, Saudi Arabia
| |
Collapse
|
2
|
Drost FJ, Keunen K, Moeskops P, Claessens NHP, van Kalken F, Išgum I, Voskuil-Kerkhof ESM, Groenendaal F, de Vries LS, Benders MJNL, Termote JUM. Severe retinopathy of prematurity is associated with reduced cerebellar and brainstem volumes at term and neurodevelopmental deficits at 2 years. Pediatr Res 2018; 83:818-824. [PMID: 29320482 DOI: 10.1038/pr.2018.2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 12/24/2017] [Indexed: 11/09/2022]
Abstract
BackgroundTo evaluate the association between severe retinopathy of prematurity (ROP), measures of brain morphology at term-equivalent age (TEA), and neurodevelopmental outcome.MethodsEighteen infants with severe ROP (median gestational age (GA) 25.3 (range 24.6-25.9 weeks) were included in this retrospective case-control study. Each infant was matched to two extremely preterm control infants (n=36) by GA, birth weight, sex, and brain injury. T2-weighted images were obtained on a 3 T magnetic resonance imaging (MRI) at TEA. Brain volumes were computed using an automatic segmentation method. In addition, cortical folding metrics were extracted. Neurodevelopment was formally assessed at the ages of 15 and 24 months.ResultsInfants with severe ROP had smaller cerebellar volumes (21.4±3.2 vs. 23.1±2.6 ml; P=0.04) and brainstem volumes (5.4±0.5 ml vs. 5.8±0.5 ml; P=0.01) compared with matched control infants. Furthermore, ROP patients showed a significantly lower development quotient (Griffiths Mental Development Scales) at the age of 15 months (93±15 vs. 102±10; P=0.01) and lower fine motor scores (10±3 vs. 12±2; P=0.02) on Bayley Scales (Third Edition) at the age of 24 months.ConclusionSevere ROP was associated with smaller volumes of the cerebellum and brainstem and with poorer early neurodevelopmental outcome. Follow-up through childhood is needed to evaluate the long-term consequences of our findings.
Collapse
Affiliation(s)
- Femke J Drost
- Department of Neonatology, Wilhelmina Children's Hospital, University Medical Center Utrecht and Utrecht University, Utrecht, Netherlands
| | - Kristin Keunen
- Department of Neonatology, Wilhelmina Children's Hospital, University Medical Center Utrecht and Utrecht University, Utrecht, Netherlands
| | - Pim Moeskops
- Image Sciences Institute, University Medical Center Utrecht and Utrecht University, Utrecht, Netherlands
| | - Nathalie H P Claessens
- Department of Neonatology, Wilhelmina Children's Hospital, University Medical Center Utrecht and Utrecht University, Utrecht, Netherlands
| | - Femke van Kalken
- Department of Neonatology, Wilhelmina Children's Hospital, University Medical Center Utrecht and Utrecht University, Utrecht, Netherlands
| | - Ivana Išgum
- Image Sciences Institute, University Medical Center Utrecht and Utrecht University, Utrecht, Netherlands
| | | | - Floris Groenendaal
- Department of Neonatology, Wilhelmina Children's Hospital, University Medical Center Utrecht and Utrecht University, Utrecht, Netherlands
| | - Linda S de Vries
- Department of Neonatology, Wilhelmina Children's Hospital, University Medical Center Utrecht and Utrecht University, Utrecht, Netherlands
| | - Manon J N L Benders
- Department of Neonatology, Wilhelmina Children's Hospital, University Medical Center Utrecht and Utrecht University, Utrecht, Netherlands
| | - Jacqueline U M Termote
- Department of Neonatology, Wilhelmina Children's Hospital, University Medical Center Utrecht and Utrecht University, Utrecht, Netherlands
| |
Collapse
|
3
|
Bieghs L, Johnsen HE, Maes K, Menu E, Van Valckenborgh E, Overgaard MT, Nyegaard M, Conover CA, Vanderkerken K, De Bruyne E. The insulin-like growth factor system in multiple myeloma: diagnostic and therapeutic potential. Oncotarget 2018; 7:48732-48752. [PMID: 27129151 PMCID: PMC5217049 DOI: 10.18632/oncotarget.8982] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 04/16/2016] [Indexed: 12/14/2022] Open
Abstract
Multiple myeloma (MM) is a highly heterogeneous plasma cell malignancy. The MM cells reside in the bone marrow (BM), where reciprocal interactions with the BM niche foster MM cell survival, proliferation, and drug resistance. As in most cancers, the insulin-like growth factor (IGF) system has been demonstrated to play a key role in the pathogenesis of MM. The IGF system consists of IGF ligands, IGF receptors, IGF binding proteins (IGFBPs), and IGFBP proteases and contributes not only to the survival, proliferation, and homing of MM cells, but also MM-associated angiogenesis and osteolysis. Furthermore, increased IGF-I receptor (IGF-IR) expression on MM cells correlates with a poor prognosis in MM patients. Despite the prominent role of the IGF system in MM, strategies targeting the IGF-IR using blocking antibodies or small molecule inhibitors have failed to translate into the clinic. However, increasing preclinical evidence indicates that IGF-I is also involved in the development of drug resistance against current standard-of-care agents against MM, including proteasome inhibitors, immunomodulatory agents, and corticoids. IGF-IR targeting has been able to overcome or revert this drug resistance in animal models, enhancing the efficacy of standard-of-care agents. This finding has generated renewed interest in the therapeutic potential of IGF-I targeting in MM. The present review provides an update of the impact of the different IGF system components in MM and discusses the diagnostic and therapeutic potentials.
Collapse
Affiliation(s)
- Liesbeth Bieghs
- Department of Hematology and Immunology, Myeloma Center Brussels, Vrije Universiteit Brussel, Brussels, Belgium.,Department of Hematology, Aalborg Hospital, Aalborg University, Denmark.,Department of Biomedicin, Aarhus University, Aarhus, Denmark
| | - Hans E Johnsen
- Department of Hematology, Aalborg Hospital, Aalborg University, Denmark.,Clinical Cancer Research Center, Aalborg University Hospital, Denmark.,Department of Clinical Medicine, Aalborg University, Denmark
| | - Ken Maes
- Department of Hematology and Immunology, Myeloma Center Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Eline Menu
- Department of Hematology and Immunology, Myeloma Center Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Els Van Valckenborgh
- Department of Hematology and Immunology, Myeloma Center Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | | | - Mette Nyegaard
- Department of Biomedicin, Aarhus University, Aarhus, Denmark
| | - Cheryl A Conover
- Division of Endocrinology, Metabolism and Nutrition, Endocrine Research Unit, Mayo Clinic, Rochester, NY, USA
| | - Karin Vanderkerken
- Department of Hematology and Immunology, Myeloma Center Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Elke De Bruyne
- Department of Hematology and Immunology, Myeloma Center Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| |
Collapse
|
4
|
Dean M, Lassak A, Wilk A, Zapata A, Marrero L, Molina P, Reiss K. Acute Ethanol Increases IGF-I-Induced Phosphorylation of ERKs by Enhancing Recruitment of p52-Shc to the Grb2/Shc Complex. J Cell Physiol 2017; 232:1275-1286. [PMID: 27607558 PMCID: PMC5381968 DOI: 10.1002/jcp.25586] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 09/06/2016] [Indexed: 12/13/2022]
Abstract
Ethanol plays a detrimental role in the development of the brain. Multiple studies have shown that ethanol inhibits insulin-like growth factor I receptor (IGF-IR) function. Because the IGF-IR contributes to brain development by supporting neural growth, survival, and differentiation, we sought to determine the molecular mechanism(s) involved in ethanol's effects on this membrane-associated tyrosine kinase. Using multiple neuronal cell types, we performed Western blot, immunoprecipitation, and GST-pulldowns following acute (1-24 h) or chronic (3 weeks) treatment with ethanol. Surprisingly, exposure of multiple neuronal cell types to acute (up to 24 h) ethanol (50 mM) enhanced IGF-I-induced phosphorylation of extracellular regulated kinases (ERKs), without affecting IGF-IR tyrosine phosphorylation itself, or Akt phosphorylation. This acute increase in ERKs phosphorylation was followed by the expected inhibition of the IGF-IR signaling following 3-week ethanol exposure. We then expressed a GFP-tagged IGF-IR construct in PC12 cells and used them to perform fluorescence recovery after photobleaching (FRAP) analysis. Using these fluorescently labeled cells, we determined that 50 mM ethanol decreased the half-time of the IGF-IR-associated FRAP, which implied that cell membrane-associated signaling events could be affected. Indeed, co-immunoprecipitation and GST-pulldown studies demonstrated that the acute ethanol exposure increased the recruitment of p52-Shc to the Grb2-Shc complex, which is known to engage the Ras-Raf-ERKs pathway following IGF-1 stimulation. These experiments indicate that even a short and low-dose exposure to ethanol may dysregulate function of the receptor, which plays a critical role in brain development. J. Cell. Physiol. 232: 1275-1286, 2017. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Matthew Dean
- Alcohol and Drug Abuse Center of Excellence, Department of Physiology, LSU Health New Orleans, New Orleans, LA, 70112
- Department of Genetics, LSU Health New Orleans
- Stanley S. Scott Cancer Center, LSU Health New Orleans
| | - Adam Lassak
- Stanley S. Scott Cancer Center, LSU Health New Orleans
| | - Anna Wilk
- University of South Alabama Mitchell Cancer Institute, Mobile, AL, 36604
| | | | - Luis Marrero
- Morphology and Imaging Core, LSU Health New Orleans
| | - Patricia Molina
- Alcohol and Drug Abuse Center of Excellence, Department of Physiology, LSU Health New Orleans, New Orleans, LA, 70112
| | | |
Collapse
|
5
|
Wrigley S, Arafa D, Tropea D. Insulin-Like Growth Factor 1: At the Crossroads of Brain Development and Aging. Front Cell Neurosci 2017; 11:14. [PMID: 28203146 PMCID: PMC5285390 DOI: 10.3389/fncel.2017.00014] [Citation(s) in RCA: 143] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 01/16/2017] [Indexed: 12/15/2022] Open
Abstract
Insulin-like growth factor 1 (IGF1) is a polypeptide hormone structurally similar to insulin. It is central to the somatotropic axis, acting downstream of growth hormone (GH). It activates both the mitogen-activated protein (MAP) kinase and PI3K signaling pathways, acting in almost every tissue in the body to promote tissue growth and maturation through upregulation of anabolic processes. Overall GH and IGF1 signaling falls with age, suggesting that it is this reduced IGF1 activity that leads to age-related changes in organisms. However, mutations that reduce IGF1-signaling activity can dramatically extend the lifespan of organisms. Therefore, the role of IGF1 in the overall aging process is unclear. This review article will focus on the role of IGF1 in brain development and aging. The evidence points towards a role for IGF1 in neurodevelopment both prenatally and in the early post-natal period, and in plasticity and remodeling throughout life. This review article will then discuss the hallmarks of aging and cognitive decline associated with falls in IGF1 levels towards the end of life. Finally, the role of IGF1 will be discussed within the context of both neuropsychiatric disorders caused by impaired development of the nervous system, and neurodegenerative disorders associated with aging. IGF1 and its derivatives are shown to improve the symptoms of certain neuropsychiatric disorders caused by deranged neurodevelopment and these effects have been correlated with changes in the underlying biology in both in vitro and in vivo studies. On the other hand, studies looking at IGF1 in neurodegenerative diseases have been conflicting, supporting both a role for increased and decreased IGF1 signaling in the underlying pathogenesis of these diseases.
Collapse
Affiliation(s)
- Sarah Wrigley
- School of Medicine, Trinity College Dublin Dublin, Ireland
| | - Donia Arafa
- School of Medicine, Trinity College Dublin Dublin, Ireland
| | - Daniela Tropea
- Neuropsychiatric Genetics, Trinity Translational Medicine Institute St. James HospitalDublin, Ireland; Institute of Neuroscience, Trinity College DublinDublin, Ireland
| |
Collapse
|
6
|
Bryan MR, Bowman AB. Manganese and the Insulin-IGF Signaling Network in Huntington's Disease and Other Neurodegenerative Disorders. ADVANCES IN NEUROBIOLOGY 2017; 18:113-142. [PMID: 28889265 PMCID: PMC6559248 DOI: 10.1007/978-3-319-60189-2_6] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Huntington's disease (HD) is an autosomal dominant neurodegenerative disease resulting in motor impairment and death in patients. Recently, several studies have demonstrated insulin or insulin-like growth factor (IGF) treatment in models of HD, resulting in potent amelioration of HD phenotypes via modulation of the PI3K/AKT/mTOR pathways. Administration of IGF and insulin can rescue microtubule transport, metabolic function, and autophagy defects, resulting in clearance of Huntingtin (HTT) aggregates, restoration of mitochondrial function, amelioration of motor abnormalities, and enhanced survival. Manganese (Mn) is an essential metal to all biological systems but, in excess, can be toxic. Interestingly, several studies have revealed the insulin-mimetic effects of Mn-demonstrating Mn can activate several of the same metabolic kinases and increase peripheral and neuronal insulin and IGF-1 levels in rodent models. Separate studies have shown mouse and human striatal neuroprogenitor cell (NPC) models exhibit a deficit in cellular Mn uptake, indicative of a Mn deficiency. Furthermore, evidence from the literature reveals a striking overlap between cellular consequences of Mn deficiency (i.e., impaired function of Mn-dependent enzymes) and known HD endophenotypes including excitotoxicity, increased reactive oxygen species (ROS) accumulation, and decreased mitochondrial function. Here we review published evidence supporting a hypothesis that (1) the potent effect of IGF or insulin treatment on HD models, (2) the insulin-mimetic effects of Mn, and (3) the newly discovered Mn-dependent perturbations in HD may all be functionally related. Together, this review will present the intriguing possibility that intricate regulatory cross-talk exists between Mn biology and/or toxicology and the insulin/IGF signaling pathways which may be deeply connected to HD pathology and, perhaps, other neurodegenerative diseases (NDDs) and other neuropathological conditions.
Collapse
Affiliation(s)
- Miles R Bryan
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA.
- Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, 37232, USA.
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, 37232, USA.
| | - Aaron B Bowman
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
- Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
- Vanderbilt Center in Molecular Toxicology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| |
Collapse
|
7
|
Park KD, Lim OK, Yoo CJ, Kim YW, Lee S, Park Y, Lee JK. Voxel-based statistical analysis of brain metabolism in patients with growth hormone deficiency after traumatic brain injury. Brain Inj 2016; 30:407-413. [PMID: 26910852 DOI: 10.3109/02699052.2015.1127997] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE The aim of this study was to investigate the regional cerebral metabolism related to growth hormone deficiency (GHD) after traumatic brain injury (TBI) using F-18 fluorodeoxyglucose positron emission tomography (F-18 FDG PET) images. METHODS Twenty-three patients with diffuse axonal injury following TBI were enrolled. They underwent brain F-18 FDG PET study and an insulin tolerance test (ITT). According to the results of ITT, they were divided into two groups: patients with GHD and subjects with TBI but normal Growth Hormone (GH). Voxel-based statistical analysis was performed and the regional cerebral glucose metabolism shown on F-18 FDG PET from 10 patients with GHD was compared with those from 13 patients without GHD. Analysis was performed using SPM2 to identify regions where decreased changes in regional cerebral glucose metabolism were significantly related to GHD. RESULTS Compared with subjects with TBI but normal GH, patients with GHD after TBI showed decreased cerebral glucose metabolism in the Left superior frontal gyrus, Right angular gyrus, Right superior temporal gyrus, Left inferior temporal gyrus, Left anterior and middle cingulate gyrus and Right anterior and middle cingulate gyrus. (puncorrected < 0.005). CONCLUSIONS The findings are suggestive of the brain region influenced by GHD. These cortical areas are involved in regulation of intellectual function, executive function and working memory.
Collapse
Affiliation(s)
| | | | - Chan Jong Yoo
- b Department of Neurosurgery , Gachon University, Gil Medical Centre , Incheon , Republic of Korea
| | - Yong Wook Kim
- c Department and Research Institute of Rehabilitation Medicine Yonsei University College of Medicine , Seoul , Republic of Korea
| | - Sihoon Lee
- d Department of Internal Medicine and Laboratory of Molecular Endocrinology , Gachon University, Gil Medical Centre , Incheon , Republic of Korea
| | - Yongbum Park
- e Department of Rehabilitation Medicine , Inje University Sanggye Paik Hospital, Inje University College of Medicine , Seoul , Republic of Korea
| | | |
Collapse
|
8
|
Insulin-Like Growth Factor-1 Receptor Is Differentially Distributed in Developing Cerebellar Cortex of Rats Born to Diabetic Mothers. J Mol Neurosci 2015; 58:221-32. [DOI: 10.1007/s12031-015-0661-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2015] [Accepted: 09/30/2015] [Indexed: 01/04/2023]
|
9
|
Chaplin JE, Kriström B, Jonsson B, Tuvemo T, Albertsson-Wikland K. Growth Hormone Treatment Improves Cognitive Function in Short Children with Growth Hormone Deficiency. Horm Res Paediatr 2015; 83:000375529. [PMID: 25823753 DOI: 10.1159/000375529] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 01/27/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS We investigated the association between cognition and growth hormone (GH) status and GH treatment in short prepubertal children with broadly ranging GH secretion. METHODS A total of 99 children (age 3-11 years), 41 with GH deficiency (GHD) and 58 with idiopathic short stature (ISS), were randomized to a fixed dose (43 µg/kg/day) or a prediction model-guided individualized dose (17-100 µg/kg/day) and followed up for 24 months. In a longitudinal and mixed within- and between-subjects study, we examined clinical effect size changes, measured by Cohen's d, in full-scale IQ (FSIQ) and secondary IQ indices. RESULTS Significant increases giving medium effect size in FSIQ (p = 0.001, Cohen's d = 0.63), performance IQ (p = 0.001, Cohen's d = 0.65) and processing speed (p = 0.005, Cohen's d = 0.71) were found in the GH-deficient group. In contrast, perceptual organization only increased in the ISS group (p = 0.001, Cohen's d = 0.53). Baseline IQ was normally distributed with small but significant differences between the groups: GH-deficient children had lower FSIQ (p = 0.042) and lower performance IQ (p = 0.021). Using multiple regression analysis, 40% of the variance in delta processing speed scores (0-24 months) was explained by GHmax and IGF-ISDS at baseline. CONCLUSION IQ, specifically fluid intelligence, increased in the GH-deficient children. The pretreatment status of the GH/IGF-I axis was significantly predictive for these changes. © 2015 S. Karger AG, Basel.
Collapse
Affiliation(s)
- John Eric Chaplin
- Gothenburg Pediatric Growth Research Center, Department of Pediatrics, Institute of Clinical Science, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | | | | | | | | |
Collapse
|
10
|
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.
Collapse
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
| |
Collapse
|
11
|
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
| |
Collapse
|
12
|
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.
Collapse
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
| |
Collapse
|
13
|
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.
Collapse
|
14
|
Collins-Hooper H, Luke G, Cranfield M, Otto WR, Ray S, Patel K. Efficient myogenic reprogramming of adult white fat stem cells and bone marrow stem cells by freshly isolated skeletal muscle fibers. Transl Res 2011; 158:334-43. [PMID: 22061041 DOI: 10.1016/j.trsl.2011.07.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 07/26/2011] [Accepted: 07/29/2011] [Indexed: 11/16/2022]
Abstract
Stem cells that can be directed to differentiate into specific cell types offer the prospect of a renewable source of replacement cells to treat diseases. This study evaluates the reprogramming of 2 readily available stem cell populations into skeletal muscle. We show for the first time that freshly isolated muscle fibers reprogram bone marrow or white fat stem cells far more efficiently than muscle cell lines. In addition, we show that the ability of muscle fibers to reprogram stem cells can be almost doubled through the use of chromatin remodeling reagents such as trichostatin A. This novel approach permits the generation of myogenic cells that could be used to treat a range of muscle-wasting diseases.
Collapse
|
15
|
Growth hormone and prolactin regulate human neural stem cell regenerative activity. Neuroscience 2011; 190:409-27. [PMID: 21664953 DOI: 10.1016/j.neuroscience.2011.05.029] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 05/10/2011] [Accepted: 05/12/2011] [Indexed: 12/18/2022]
Abstract
We have previously shown that the growth hormone (GH)/prolactin (PRL) axis has a significant role in regulating neuroprotective and/or neurorestorative mechanisms in the brain and that these effects are mediated, at least partly, via actions on neural stem cells (NSCs). Here, using NSCs with properties of neurogenic radial glia derived from fetal human forebrains, we show that exogenously applied GH and PRL promote the proliferation of NSCs in the absence of epidermal growth factor or basic fibroblast growth factor. When applied to differentiating NSCs, they both induce neuronal progenitor proliferation, but only PRL has proliferative effects on glial progenitors. Both GH and PRL also promote NSC migration, particularly at higher concentrations. Since human GH activates both GH and PRL receptors, we hypothesized that at least some of these effects may be mediated via the latter. Migration studies using receptor-specific antagonists confirmed that GH signals via the PRL receptor promote migration. Mechanisms of receptor signaling in NSC proliferation, however, remain to be elucidated. In summary, GH and PRL have complex stimulatory and modulatory effects on NSC activity and as such may have a role in injury-related recovery processes in the brain.
Collapse
|
16
|
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.
Collapse
Affiliation(s)
- Ping Ye
- Department of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7039, USA.
| | | | | | | | | |
Collapse
|
17
|
Ohlsson C, Mohan S, Sjögren K, Tivesten A, Isgaard J, Isaksson O, Jansson JO, Svensson J. The role of liver-derived insulin-like growth factor-I. Endocr Rev 2009; 30:494-535. [PMID: 19589948 PMCID: PMC2759708 DOI: 10.1210/er.2009-0010] [Citation(s) in RCA: 295] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
IGF-I is expressed in virtually every tissue of the body, but with much higher expression in the liver than in any other tissue. Studies using mice with liver-specific IGF-I knockout have demonstrated that liver-derived IGF-I, constituting a major part of circulating IGF-I, is an important endocrine factor involved in a variety of physiological and pathological processes. Detailed studies comparing the impact of liver-derived IGF-I and local bone-derived IGF-I demonstrate that both sources of IGF-I can stimulate longitudinal bone growth. We propose here that liver-derived circulating IGF-I and local bone-derived IGF-I to some extent have overlapping growth-promoting effects and might have the capacity to replace each other (= redundancy) in the maintenance of normal longitudinal bone growth. Importantly, and in contrast to the regulation of longitudinal bone growth, locally derived IGF-I cannot replace (= lack of redundancy) liver-derived IGF-I for the regulation of a large number of other parameters including GH secretion, cortical bone mass, kidney size, prostate size, peripheral vascular resistance, spatial memory, sodium retention, insulin sensitivity, liver size, sexually dimorphic liver functions, and progression of some tumors. It is clear that a major role of liver-derived IGF-I is to regulate GH secretion and that some, but not all, of the phenotypes in the liver-specific IGF-I knockout mice are indirect, mediated via the elevated GH levels. All of the described multiple endocrine effects of liver-derived IGF-I should be considered in the development of possible novel treatment strategies aimed at increasing or reducing endocrine IGF-I activity.
Collapse
Affiliation(s)
- Claes Ohlsson
- Division of Endocrinology, Institute of Medicine, Sahlgrenska University Hospital, Göteborg, Sweden.
| | | | | | | | | | | | | | | |
Collapse
|
18
|
Abstract
Signaling through the type 1 IGF receptor (IGF1R) after interaction with IGF-I is crucial to the normal brain development. Manipulations of the mouse genome leading to changes in the expression of IGF-I or IGF1R significantly alters brain growth, such that IGF-I overexpression leads to brain overgrowth, whereas null mutations in either IGF-I or the IGF1R result in brain growth retardation. IGF-I signaling stimulates the proliferation, survival, and differentiation of each of the major neural lineages, neurons, oligodendrocytes, and astrocytes, as well as possibly influencing neural stem cells. During embryonic life, IGF-I stimulates neuron progenitor proliferation, whereas later it promotes neuron survival, neuritic outgrowth, and synaptogenesis. IGF-I also stimulates oligodendrocyte progenitor proliferation although inhibiting apoptosis in oligodendrocyte lineage cells and stimulating myelin production. These pleiotropic IGF-I activities indicate that other factors provide instructive signals for specific cellular events and that IGF-I acts to facilitate them. Studies of the few humans with IGF-I and/or IGF1R gene mutations indicate that IGF-I serves a similar role in man.
Collapse
Affiliation(s)
- A Joseph D'Ercole
- Department of Pediatrics, CB 7039, University of North Carolina, Chapel Hill, North Carolina 27599-7039, USA.
| | | |
Collapse
|
19
|
Mangold JE, Hill DL. Postnatal reorganization of primary afferent terminal fields in the rat gustatory brainstem is determined by prenatal dietary history. J Comp Neurol 2008; 509:594-607. [PMID: 18546275 DOI: 10.1002/cne.21760] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Dietary manipulation has been used as an experimental strategy to gain insight into the normal development of the gustatory system. Institution of a diet low in sodium chloride (NaCl) from embryonic day 3 (E3) to E12 (E3-E12 sodium-restricted rats) yields dramatically enlarged terminal fields of the chorda tympani (CT), greater superficial petrosal (GSP), and glossopharyngeal (IX) nerves in the rostral pole of the nucleus of the solitary tract (NTS) at adulthood. To examine how this early, limited dietary manipulation affects postnatal terminal field development, we used a triple anterograde nerve label procedure at postnatal day 15 (P15), P25, P35, and > or =P40 (adults) in two groups: rats fed a commercial diet replete in sodium (controls) and E3-E12 sodium-restricted rats. Results showed an age-related decrease in terminal field volumes of all three nerves during normal development. In contrast, E3-E12 sodium-restricted rats displayed age-related increases of the CT and IX terminal fields, with the terminal field volume of the GSP remaining unchanged throughout development. NTS volume did not grow after P15; therefore, alterations in terminal field volumes are not due to parallel alterations in the size of the NTS. Our data suggest that the age-related decrease in terminal fields observed in controls may reflect activity-dependent pruning of afferent terminals, whereas terminal field increases seen in E3-E12 sodium-restricted rats may reflect cellular/molecular differences in the NTS induced predominantly by activity-independent mechanisms. These findings predict a significant difference in the development of neural coding and sensory-guided behaviors between E3-E12 sodium-restricted rats and controls.
Collapse
Affiliation(s)
- Jamie E Mangold
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, Virginia 22911, USA
| | | |
Collapse
|
20
|
Beardsall K, Vanhaesebrouck S, Ogilvy-Stuart AL, Ahluwalia JS, Vanhole C, Palmer C, Midgley P, Thompson M, Cornette L, Weissenbruch M, Thio M, de Zegher F, Dunger D. A randomised controlled trial of early insulin therapy in very low birth weight infants, "NIRTURE" (neonatal insulin replacement therapy in Europe). BMC Pediatr 2007; 7:29. [PMID: 17692117 PMCID: PMC1994677 DOI: 10.1186/1471-2431-7-29] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2006] [Accepted: 08/10/2007] [Indexed: 01/04/2023] Open
Abstract
Background Studies in adult intensive care have highlighted the importance of insulin and improved glucose control on survival, with 32% reduction in mortality, 22% reduction in intensive care stay and halving of the incidence of bacteraemia. Very low birth weight infants requiring intensive care also have relative insulin deficiency often leading to hyperglycaemia during the first week of life. The physiological influences on insulin secretion and sensitivity, and the potential importance of glucose control at this time are not well established. However there is increasing evidence that the early postnatal period is critical for pancreatic development. At this time a complex set of signals appears to influence pancreatic development and β cell survival. This has implications both in terms of acute glucose control but also relative insulin deficiency is likely to play a role in poor postnatal growth, which has been associated with later motor and cognitive impairment, and fewer β cells are linked to risk of type 2 diabetes later in life. Methods A multi-centre, randomised controlled trial of early insulin replacement in very low birth weight babies (VLBW, birth weight < 1500 g). 500 infants will be recruited from 10 centres in the UK and Europe. Babies will be randomised to receive a continuous insulin infusion (0.05 units/kg/h) or to receive standard neonatal care from the first day of life and for the next 7 days. If blood glucose (BG) levels fall infants will receive 20% dextrose titrated to maintain normoglycaemia (4–8 mmol/l). If BG is consistently above 10 mmol/l babies will receive standard treatment with additional insulin infusion. The primary end point will be mortality on or before expected date of delivery, secondary end points will be markers of morbidity and include episodes of sepsis, severity of retinopathy, chronic lung disease and growth. Trial Registration Current Controlled Trials ISRCTN78428828. EUDRACT Number 2004-002170-34
Collapse
Affiliation(s)
- Kathryn Beardsall
- Department of Paediatrics, University of Cambridge, Addenbrooke's Hospital NHS Trust, Hills Road, Cambridge, CB2 2QQ, UK
- Neonatal Unit, Rosie Hospital, Hills Road, Cambridge, CB2 2QQ, UK
| | | | | | - Jag S Ahluwalia
- Neonatal Unit, Rosie Hospital, Hills Road, Cambridge, CB2 2QQ, UK
| | - Christine Vanhole
- Neonatal Unit, Kindergeneeskunde, UZ, Herestraat 49, B3000, Leuven, Belgium
| | - Christopher Palmer
- Centre for Applied Medical Statistics, Department of Public Health and Primary Care, University of Cambridge, UK
| | - Paula Midgley
- Simpson Centre for Reproductive Health, Royal Infirmary of Edinburgh, 51 Little France Crescent, Edinburgh, EH16 4SA, UK
| | - Mike Thompson
- Department of Paediatrics, Luton and Dunstable Hospital, Lewsey Road, Luton, LU4 0DZ, UK
| | - Luc Cornette
- Neonatal Unit, Leeds General Infirmary, Great George Street, Leeds, LS1 3EX, UK
| | | | - Marta Thio
- Neonatal Unit, Hospital Universitari, Passeig Sant Joan de Deu, number 2, 08950 Esplugues-Barcelona, Spain
| | - Francis de Zegher
- Neonatal Unit, Kindergeneeskunde, UZ, Herestraat 49, B3000, Leuven, Belgium
| | - David Dunger
- Department of Paediatrics, University of Cambridge, Addenbrooke's Hospital NHS Trust, Hills Road, Cambridge, CB2 2QQ, UK
| |
Collapse
|
21
|
McDonald TJ, Nijland MJ, Nathanielsz PW. The insulin-like growth factor system and the fetal brain: effects of poor maternal nutrition. Rev Endocr Metab Disord 2007; 8:71-84. [PMID: 17653868 DOI: 10.1007/s11154-007-9044-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The insulin-like growth factor (IGF) signaling system plays indispensable roles in pre- and post-natal brain growth and development. A large body of studies using both in vivo null mutant and transgenic mice and in vitro neuronal culture techniques indicate that IGF-I acts directly on the brain while IGF-II effects are mediated to a large extent by IGF-II control of placental growth. It appears that all of the mechanisms, except migration, that are involved in normal brain development, e.g., proliferation, apoptosis, maturation and differentiation, are influenced by IGF-I. While IGF system members are produced in the brain, recent reports in post-natal animals indicate that normal brain health and function are dependent upon transfer of circulating IGF-I from the liver and its transfer across the blood brain barrier. Data showing that this phenomenon applies to pre-natal brain growth and development would make an important contribution to fetal physiology. A number of kinase pathways are able to participate in IGF signaling in brain with respect to nutrient restriction; among the most important are the PI3K/AKT, Ras-Raf-MEK-ERK and mTOR-nutrient sensing pathways. Both maternal and fetal IGF-I peripheral plasma concentrations are greatly reduced in nutrient restriction while IGF-II does not appear to be affected. Nutrient restriction also affects IGF binding protein concentrations while effects on the IGF-I receptor appear to vary with the paradigm. Studies on the effects of nutrient restriction on the fetal primate brain in relation to activity of the IGF system are needed to determine the applicability of rodent studies to humans.
Collapse
Affiliation(s)
- Thomas J McDonald
- Center for Pregnancy and Newborn Research, Department of Obstetrics and Gynecology, University of Texas Health Science Center, San Antonio, TX 78253, USA
| | | | | |
Collapse
|
22
|
Mangold JE, Hill DL. Extensive reorganization of primary afferent projections into the gustatory brainstem induced by feeding a sodium-restricted diet during development: less is more. J Neurosci 2007; 27:4650-62. [PMID: 17460078 PMCID: PMC2613514 DOI: 10.1523/jneurosci.4518-06.2007] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neural development is especially vulnerable to environmental influences during periods of neurogenesis and rapid maturation. In fact, short periods of environmental manipulations confined to embryonic development lead to significant changes in morphology and function. A guiding principal emerging from studies of sensory systems is that experimentally induced effects are most dramatic in higher neural levels (e.g., cortex) and primarily involve postnatal synaptic refinements. In contrast to other sensory systems, the gustatory system is particularly susceptible to the effects of deprivation much earlier and with profound changes evident in the brainstem. Here we show that feeding pregnant rats a custom diet featuring a low-sodium content for 9 d before the tongue appears in the fetus produces extensive restructuring of the gustatory brainstem. Rats born to mothers fed the custom diet from embryonic day 3 (E3) to E12 have terminal field volumes of the greater superficial petrosal, chorda tympani, and glossopharyngeal nerves at adulthood that are expanded as much as 10 times beyond that found in rats fed a standard rat chow. The widespread alterations are not attributable to increased numbers of nerve cells, increased target size, or obvious changes in peripheral taste function. Moreover, we show that the limited period of feeding the custom diet has much larger effects than if rats were fed the diet to postweaning ages. Our results suggest that early periods of altered experience, especially during nucleus of the solitary tract neurogenesis, leads to a restructuring of the gustatory brainstem, which in turn may impact the control of sensory and homeostatic processes.
Collapse
Affiliation(s)
- Jamie E. Mangold
- Department of Psychology, University of Virginia, Charlottesville, Virginia 22904-4400
| | - David L. Hill
- Department of Psychology, University of Virginia, Charlottesville, Virginia 22904-4400
| |
Collapse
|
23
|
Hodge RD, D’Ercole AJ, O’Kusky JR. Insulin-like growth factor-I (IGF-I) inhibits neuronal apoptosis in the developing cerebral cortex in vivo. Int J Dev Neurosci 2007; 25:233-41. [PMID: 17459648 PMCID: PMC2255566 DOI: 10.1016/j.ijdevneu.2007.03.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2006] [Revised: 02/05/2007] [Accepted: 03/12/2007] [Indexed: 11/18/2022] Open
Abstract
Increased expression of insulin-like growth factor-I (IGF-I) in embryonic neural progenitors in vivo has been shown to accelerate neuron proliferation in the neocortex. In the present study, the in vivo actions of (IGF-I) on naturally occurring neuron death in the cerebral cortex were investigated during embryonic and early postnatal development in a line of transgenic (Tg) mice that overexpress IGF-I in the brain, directed by nestin genomic regulatory elements, beginning at least as early as embryonic day (E) 13. The areal density of apoptotic cells (N(A), cells/mm2) at E16 in the telencephalic wall of Tg and littermate control embryos was determined by immunostaining with an antibody specific for activated caspase-3. Stereological analyses were conducted to measure the numerical density (N(V), cells/mm3) and total number of immunoreactive apoptotic cells in the cerebral cortex of nestin/IGF-I Tg and control mice at postnatal days (P) 0 and 5. The volume of cerebral cortex and both the N(V) and total number of all cortical neurons also were determined in both cerebral hemispheres at P0, P5 and P270. Apoptotic cells were rare in the embryonic telencephalic wall at E16. However, the overall N(A) of apoptotic cells was found to be significantly less by 46% in Tg embryos. The volume of the cerebral cortex was significantly greater in Tg mice at P0 (30%), P5 (13%) and P270 (26%). The total number of cortical neurons in Tg mice was significantly increased at P0 (29%), P5 (29%) and P270 (31%), although the N(V) of cortical neurons did not differ significantly between Tg and control mice at any age. Transgenic mice at P0 and P5 exhibited significant decreases in the N(V) of apoptotic cells in the cerebral cortex (31% and 39%, respectively). The vast majority of these apoptotic cells (> 90%) were judged to be neurons by their morphological appearance. Increased expression of IGF-I inhibits naturally occurring (i.e. apoptotic) neuron death during early postnatal development of the cerebral cortex to a degree that sustains a persistent increase in total neuron number even in the adult animal.
Collapse
Affiliation(s)
- Rebecca D. Hodge
- Department of Pathology and Laboratory Medicine, University of British Columbia and the Child & Family Research Institute, 950 West 28th Avenue, Vancouver, British Columbia V5Z 4H4, Canada
| | - A. Joseph D’Ercole
- Department of Pediatrics, Division of Endocrinology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7220, USA
| | - John R. O’Kusky
- Department of Pathology and Laboratory Medicine, University of British Columbia and the Child & Family Research Institute, 950 West 28th Avenue, Vancouver, British Columbia V5Z 4H4, Canada
- *Corresponding author. Tel.: +1 604 875 2000x5095; fax: +1 604 875 3597. E-mail address: (J.R. O’Kusky)
| |
Collapse
|
24
|
Richards GD. Genetic, physiologic and ecogeographic factors contributing to variation in Homo sapiens: Homo floresiensis reconsidered. J Evol Biol 2006; 19:1744-67. [PMID: 17040372 DOI: 10.1111/j.1420-9101.2006.01179.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A new species, Homo floresiensis, was recently named for Pleistocene hominid remains on Flores, Indonesia. Significant controversy has arisen regarding this species. To address controversial issues and refocus investigations, I examine the affinities of these remains with Homo sapiens. Clarification of problematic issues is sought through an integration of genetic and physiological data on brain ontogeny and evolution. Clarification of the taxonomic value of various 'primitive' traits is possible given these data. Based on this evidence and using a H. sapiens morphological template, models are developed to account for the combination of features displayed in the Flores fossils. Given this overview, I find substantial support for the hypothesis that the remains represent a variant of H. sapiens possessing a combined growth hormone-insulin-like growth factor I axis modification and mutation of the MCPH gene family. Further work will be required to determine the extent to which this variant characterized the population.
Collapse
Affiliation(s)
- Gary D Richards
- Human Evolution Research Center, University of California, Berkeley, CA 94720, USA.
| |
Collapse
|
25
|
Hill D, May O. Development and Plasticity of the Gustatory Portion of Nucleus of the Solitary Tract. Front Neurosci 2006. [DOI: 10.1201/9781420005974.ch6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
|
26
|
May OL, Hill DL. Gustatory terminal field organization and developmental plasticity in the nucleus of the solitary tract revealed through triple-fluorescence labeling. J Comp Neurol 2006; 497:658-69. [PMID: 16739199 PMCID: PMC2724654 DOI: 10.1002/cne.21023] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Early dietary sodium restriction has profound influences on the organization of the gustatory brainstem. However, the anatomical relationships among multiple gustatory nerve inputs have not been examined. Through the use of triple-fluorescence labeling and confocal laser microscopy, terminal fields of the greater superficial petrosal (GSP), chorda tympani (CT), and glossopharyngeal (IX) nerves were visualized concurrently in the nucleus of the solitary tract (NTS) of developmentally sodium-restricted and control rats. Dietary sodium restriction during pre- and postnatal development resulted in a twofold increase in the volume of both the CT and the IX nerve terminal fields but did not affect the volume of the GSP terminal field. In controls, these nerve terminal fields overlapped considerably. The dietary manipulation significantly increased the overlapping zones among terminal fields, resulting in an extension of CT and IX fields past their normal boundaries. The differences in terminal field volumes were exaggerated when expressed relative to the respective NTS volumes. Furthermore, increased terminal field volumes could not be attributed to an increase in the number of afferents because ganglion cell counts did not differ between groups. Taken together, selective increases in terminal field volume and ensuing overlap among terminal fields suggest an increased convergence of these gustatory nerve terminals onto neurons in the NTS. The genesis of such convergence is likely related to disruption of cellular and molecular mechanisms during the development of individual terminal fields, the consequences of which have implications for corresponding functional and behavioral alterations.
Collapse
Affiliation(s)
- Olivia L. May
- Department of Psychology, PO Box 400400, University of Virginia, Charlottesville, VA 22904-4400
| | - David L. Hill
- Department of Psychology, PO Box 400400, University of Virginia, Charlottesville, VA 22904-4400
| |
Collapse
|
27
|
Ye P, D'Ercole AJ. Insulin-like growth factor actions during development of neural stem cells and progenitors in the central nervous system. J Neurosci Res 2006; 83:1-6. [PMID: 16294334 DOI: 10.1002/jnr.20688] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Insulin-like growth factor-I (IGF-I) plays a key role in normal development. Recent studies show that IGF-I exerts a wide variety actions in the central nervous system during development as well as in adulthood. This report reviews recent developments on IGF-I actions and its mechanisms in the central nervous system, with a focus on its actions during the development of neural stem cells and progenitors. Available data strongly indicate that IGF-I shortens the length of the cell cycle in neuron progenitors during embryonic life and has an influence on the growth of all neural cell types. The phosphatidylinositol-3 kinase/Akt and mitogen-activated protein kinase pathways seem to be the predominant mediators of IGF-I-stimulated neural cell proliferation and survival. IGF-I actions, however, likely depend on cell type, developmental stage, and microenvironmental milieu.
Collapse
Affiliation(s)
- Ping Ye
- Department of Pediatrics, The University of North Carolina at Chapel Hill, 27599-7220, USA.
| | | |
Collapse
|
28
|
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
| | | | | | | |
Collapse
|
29
|
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.
Collapse
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.
| | | | | | | |
Collapse
|
30
|
Hodge RD, D'Ercole AJ, O'Kusky JR. Increased expression of insulin-like growth factor-I (IGF-I) during embryonic development produces neocortical overgrowth with differentially greater effects on specific cytoarchitectonic areas and cortical layers. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2005; 154:227-37. [PMID: 15707676 DOI: 10.1016/j.devbrainres.2004.10.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2004] [Revised: 10/29/2004] [Accepted: 10/30/2004] [Indexed: 10/26/2022]
Abstract
The in vivo actions of insulin-like growth factor-I (IGF-I) on the growth and development of the cerebral cortex were investigated in transgenic (Tg) mice that overexpress IGF-I in the brain, beginning as early as embryonic day (E) 13. Compared to non-Tg littermate controls, Tg mice at postnatal day (P) 12 exhibited significant increases in total cortical volume (31%) and in total neuron number (27%). The numerical density of neurons did not differ significantly between Tg and control mice, except in layer I. Comparing cytoarchitectonic areas in Tg mice, significantly greater increases in cortical volume were found for the motor cortex (42%), compared to somatosensory cortex (35%). Similarly, greater increases in total neuron number were found for motor cortex (44%) compared to somatosensory cortex (28%). Comparing individual cortical layers in Tg mice, the greatest increase in neuron number was found in layer I for both motor (93%) and somatosensory (76%) regions, followed by layer V (36-53%)>II/III (26-47%)>VI (26-37%)>IV (22-34%). Our results demonstrate that increased expression of IGF-I in vivo during embryonic and early postnatal development produces substantial overgrowth of the neocortex. IGF-I-mediated growth and development exhibits differential effects in some cytoarchitectonic areas and in lamina-specific neuron populations, most notably the neurons of layer I.
Collapse
Affiliation(s)
- Rebecca D Hodge
- Department of Pathology and Laboratory Medicine, University of British Columbia, B.C. Research Institute for Children's and Women's Health, 950 West 28th Avenue, Vancouver, British Columbia, Canada, V5Z 4H4
| | | | | |
Collapse
|
31
|
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.
Collapse
Affiliation(s)
- Ping Ye
- Department of Pediatrics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
| | | | | | | | | | | |
Collapse
|
32
|
Sherwood CC, Hof PR, Holloway RL, Semendeferi K, Gannon PJ, Frahm HD, Zilles K. Evolution of the brainstem orofacial motor system in primates: a comparative study of trigeminal, facial, and hypoglossal nuclei. J Hum Evol 2005; 48:45-84. [PMID: 15656936 DOI: 10.1016/j.jhevol.2004.10.003] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2004] [Revised: 10/01/2004] [Accepted: 10/05/2004] [Indexed: 11/19/2022]
Abstract
The trigeminal motor (Vmo), facial (VII), and hypoglossal (XII) nuclei of the brainstem comprise the final common output for neural control of most orofacial muscles. Hence, these cranial motor nuclei are involved in the production of adaptive behaviors such as feeding, facial expression, and vocalization. We measured the volume and Grey Level Index (GLI) of Vmo, VII, and XII in 47 species of primates and examined these nuclei for scaling patterns and phylogenetic specializations. Allometric regression, using medulla volume as an independent variable, did not reveal a significant difference between strepsirrhines and haplorhines in the scaling of Vmo volume. In addition, correlation analysis using independent contrasts did not find a relationship between Vmo size or GLI and the percent of leaves in the diet. The scaling trajectory of VII volume, in contrast, differed significantly between suborders. Great ape and human VII volumes, furthermore, were significantly larger than predicted by the haplorhine regression. Enlargement of VII in these taxa may reflect increased differentiation of the facial muscles of expression and greater utilization of the visual channel in social communication. The independent contrasts of VII volume and GLI, however, were not correlated with social group size. To examine whether the human hypoglossal motor system is specialized to control the tongue for speech, we tested human XII volume and GLI for departures from nonhuman haplorhine prediction lines. Although human XII volumes were observed above the regression line, they did not exceed prediction intervals. Of note, orang-utan XII volumes had greater residuals than humans. Human XII GLI values also did not differ from allometric prediction. In sum, these findings indicate that the cranial orofacial motor nuclei evince a mosaic of phylogenetic specializations for innervation of the facial muscles of expression in the context of a generally conservative scaling relationship with respect to medulla size.
Collapse
Affiliation(s)
- Chet C Sherwood
- Department of Anthropology and School of Biomedical Sciences, Kent State University, Kent, OH 44242, USA.
| | | | | | | | | | | | | |
Collapse
|
33
|
Popken GJ, Hodge RD, Ye P, Zhang J, Ng W, O'Kusky JR, D'Ercole AJ. In vivo effects of insulin-like growth factor-I (IGF-I) on prenatal and early postnatal development of the central nervous system. Eur J Neurosci 2004; 19:2056-68. [PMID: 15090033 DOI: 10.1111/j.0953-816x.2004.03320.x] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The in vivo actions of insulin-like growth factor-I (IGF-I) on prenatal and early postnatal brain development were investigated in transgenic (Tg) mice that overexpress IGF-I prenatally under the control of regulatory sequences from the nestin gene. Tg mice demonstrated increases in brain weight of 6% by embryonic day (E) 18 and 27% by postnatal day (P) 12. In Tg embryos at E16, the volume of the cortical plate was significantly increased by 52% and total cell number was increased by 54%. S-phase labeling with 5-bromo-2'-deoxyuridine revealed a 13-15% increase in the proportion of labeled neuroepithelial cells in Tg embryos at E14. In Tg mice at P12, significant increases in regional tissue volumes were detected in the cerebral cortex (29%), subcortical white matter (52%), caudate-putamen (37%), hippocampus (49%), dentate gyrus (71%) and habenular complex (48%). Tg mice exhibited significant increases in the total number of neurons in the cerebral cortex (27%), caudate-putamen (27%), dentate gyrus (69%), medial habenular nucleus (61%) and lateral habenular nucleus (36%). In the cerebral cortex and subcortical white matter of Tg mice, the total numbers of glial cells were significantly increased by 37% and 42%, respectively. The numerical density of apoptotic cells in the cerebral cortex, labeled by antibodies against active caspase-3, was reduced by 26% in Tg mice at P7. Our results demonstrate that IGF-I can both promote proliferation of neural cells in the embryonic central nervous system in vivo and inhibit their apoptosis during postnatal life.
Collapse
Affiliation(s)
- Gregory J Popken
- Department of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7039, USA
| | | | | | | | | | | | | |
Collapse
|
34
|
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.
Collapse
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.
| | | | | | | |
Collapse
|
35
|
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.
Collapse
Affiliation(s)
- John Robert O'Kusky
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia V5Z 1M9, Canada.
| | | | | |
Collapse
|
36
|
Abstract
Insulin resistance and diabetes might promote neurodegenerative disease, but a molecular link between these disorders is unknown. Many factors are responsible for brain growth, patterning, and survival, including the insulin-insulin-like growth factor (IGF)-signaling cascades that are mediated by tyrosine phosphorylation of insulin receptor substrate (IRS) proteins. Irs2 signaling mediates peripheral insulin action and pancreatic beta-cell function, and its failure causes diabetes in mice. In this study, we reveal two important roles for Irs2 signaling in the mouse brain. First, disruption of the Irs2 gene reduced neuronal proliferation during development by 50%, which dissociated brain growth from Irs1-dependent body growth. Second, neurofibrillary tangles containing phosphorylated tau accumulated in the hippocampus of old Irs2 knock-out mice, suggesting that Irs2 signaling is neuroprotective. Thus, dysregulation of the Irs2 branch of the insulin-Igf-signaling cascade reveals a molecular link between diabetes and neurodegenerative disease.
Collapse
|
37
|
Winn N, Paul A, Musaró A, Rosenthal N. Insulin-like growth factor isoforms in skeletal muscle aging, regeneration, and disease. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2003; 67:507-18. [PMID: 12858577 DOI: 10.1101/sqb.2002.67.507] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- N Winn
- EMBL Mouse Biology Programme, 32-00016 Monterotondo, Rome, Italy
| | | | | | | |
Collapse
|
38
|
Ye P, Price W, Kassiotis G, Kollias G, D'Ercole AJ. Tumor necrosis factor-alpha regulation of insulin-like growth factor-I, type 1 IGF receptor, and IGF binding protein expression in cerebellum of transgenic mice. J Neurosci Res 2003; 71:721-31. [PMID: 12584730 DOI: 10.1002/jnr.10512] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Tumor necrosis factor-alpha (TNF-alpha), a proinflammatory cytokine, has been implicated in the pathogenesis of several disorders and injuries in the central nervous system (CNS). Unlike IGF-I, which promotes CNS growth, TNF-alpha causes brain growth retardation and neural damage. Recently TNF-alpha has been shown to inhibit IGF-I signaling and actions in non-neural tissue. To investigate whether TNF-alpha deleteriously influences brain growth by altering the IGF-I system in vivo, we examined the expression of IGF-I, the type 1 IGF receptor (IGF1R) and IGF binding proteins (IGFBPs) in the brain of transgenic (Tg) mice with murine TNF-alpha overexpression. We show that overexpression of TNF-alpha reduces the weights of whole brain and all brain regions examined during development. In adult TNF-alpha Tg mice, cerebellum (CB) exhibited the greatest reduction in weight among the five brain regions examined, being approximately 77% of that in wild-type (WT) mice. IGF-I abundance was decreased in the CB, as well as in cerebral cortex and diencephalon, of TNF-alpha Tg mice. When compared to those in WT mice, CB IGF-I abundance in Tg mice was reduced by approximately 35%, approximately 45%, and approximately 40% at 2, 6, and 9 weeks of age, respectively. Of the IGFBPs studied the abundance of IGFBP-3 and IGFBP-4 was increased by 2-3.7-fold, and the abundance of IGFBP-5 was decreased by approximately 3-fold (as judged by Western immunoblot analysis). Histological analysis and immunocytochemical staining confirmed that TNF-alpha specifically increases IGFBP-3 and IGFBP-4 immunoreactivity, as well as that of the IGF1R, in radial glial and Purkinje cells. In addition, TNF-alpha alters CB cytoarchitecture, apparently by influencing granule cell migration. Our data indicate that TNF-alpha alters the expression of IGF-I system proteins in vivo, and suggest that altered expression of IGF-I system proteins may in part explain TNF-alpha deleterious actions on brain growth.
Collapse
Affiliation(s)
- Ping Ye
- Division of Endocrinology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
| | | | | | | | | |
Collapse
|
39
|
Otteson DC, Cirenza PF, Hitchcock PF. Persistent neurogenesis in the teleost retina: evidence for regulation by the growth-hormone/insulin-like growth factor-I axis. Mech Dev 2002; 117:137-49. [PMID: 12204254 DOI: 10.1016/s0925-4773(02)00188-0] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Based on results from previous studies (J. Comp. Neurol. 394 (1998) 386, 395), it was hypothesized that the persistent neurogenesis in the retina of teleost fish is modulated by insulin-like growth factor-I (IGF-I), which, in turn, is regulated by growth hormone (GH). Two approaches were undertaken to test this hypothesis. First, a variety of techniques were used to determine if IGF-I and the IGF-I receptor (IGF-IR) are expressed in the retina. Second, GH was injected into animals to stimulate IGF-I synthesis in target tissues, and IGF-I expression and cell proliferation in the retina was quantitatively assayed. Reverse transcriptase-polymerase chain reaction, screening a retinal cDNA library and Northern analysis showed that genes encoding IGF-I and IGF-IR are expressed in the retina of goldfish. In situ hybridization showed that IGF-IR is expressed by retinal progenitors and all differentiated retinal neurons. Intraperitoneal injections of GH elevate IGF-I mRNA levels in the liver, brain and retina and produce a dose-dependent change in the proliferation of stem cells and progenitors in the retina. These data indicate that the principal components of the IGF-I signaling cascade are present in the retinas of teleosts, and we suggest these elements mediate the persistent, growth-associated neurogenesis in this tissue.
Collapse
Affiliation(s)
- D C Otteson
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | | | | |
Collapse
|
40
|
Tanaka J, Koshimura K, Murakami Y, Kato Y. Possible involvement of tetrahydrobiopterin in the trophic effect of insulin-like growth factor-1 on rat pheochromocytoma-12 (PC12) cells. Neurosci Lett 2002; 328:201-3. [PMID: 12133588 DOI: 10.1016/s0304-3940(02)00497-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Tetrahydrobiopterin (BH(4)) has a trophic effect on pheochromocytoma-12 (PC12) cells such as insulin-like growth factor-1 (IGF-1). We investigated involvement of BH(4) in the trophic effect of IGF-1 on PC12 cells. IGF-1 (10-300 ng/ml) increased cellular BH(4) content in a dose-related manner. Cellular BH(4) content increased after 6-36 h incubation with IGF-1. IGF-1-induced increase in the cellular BH(4) content was blunted by 0.3 mM 2,4-diamino-6-hydroxypyrimidine (DAHP), an inhibitor for BH(4) synthesis. IGF-1 protected PC12 cells from the cell death induced by depletion of serum and nerve growth factor, which was attenuated by DAHP. The effects of IGF-1 on the cellular BH(4) content and cell viability were eliminated by 0.2 microM wortmannin. These results suggest that BH(4) is involved in the trophic effect of IGF-1 on PC12 cells and that the effect of IGF-1 on BH(4) synthesis is mediated by phosphatidylinositol 3-kinase.
Collapse
Affiliation(s)
- Junko Tanaka
- First Division, Department of Medicine, Shimane Medical University, Izumo 693-8501, Japan
| | | | | | | |
Collapse
|
41
|
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.
Collapse
|
42
|
Jenkins LW, Peters GW, Dixon CE, Zhang X, Clark RSB, Skinner JC, Marion DW, Adelson PD, Kochanek PM. Conventional and functional proteomics using large format two-dimensional gel electrophoresis 24 hours after controlled cortical impact in postnatal day 17 rats. J Neurotrauma 2002; 19:715-40. [PMID: 12165133 DOI: 10.1089/08977150260139101] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Conventional and functional proteomics have significant potential to expand our understanding of traumatic brain injury (TBI) but have not yet been used. The purpose of the present study was to examine global hippocampal protein changes in postnatal day (PND) 17 immature rats 24 h after moderate controlled cortical impact (CCI). Silver nitrate stains or protein kinase B (PKB) phosphoprotein substrate antibodies were used to evaluate high abundance or PKB pathway signal transduction proteins representing conventional and functional proteomic approaches, respectively. Isoelectric focusing was performed over a nonlinear pH range of 3-10 with immobilized pH gradients (IPG strips) using supernatant from the most soluble cellular protein fraction of hippocampal tissue protein lysates from six paired sham and injured PND 17 rats. Approximately 1,500 proteins were found in each silver stained gel with 40% matching of proteins. Of these 600 proteins, 52% showed a twofold, 20% a fivefold, and 10% a 10-fold decrease or increase. Spot matching with existing protein databases revealed changes in important cytoskeletal and cell signalling proteins. PKB substrate protein phosphorylation was best seen in large format two-dimensional blots and known substrates of PKB such as glucose transporter proteins 3 and 4 and forkhead transcription factors, identified based upon molecular mass and charge, showed altered phosphorylation 24 h after injury. These results suggest that combined conventional and functional proteomic approaches are powerful, complementary and synergistic tools revealing multiple protein changes and posttranslational protein modifications that allow for more specific and comprehensive functional assessments after pediatric TBI.
Collapse
Affiliation(s)
- L W Jenkins
- Department of Neurosurgery, Safar Center for Resuscitation Research and University of Pittsburgh, Pittsburgh, Pennsylvania, USA. ljenkins+@pitt.edu
| | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Carter CS, Ramsey MM, Ingram RL, Cashion AB, Cefalu WT, Wang ZQ, Sonntag WE. Models of growth hormone and IGF-1 deficiency: applications to studies of aging processes and life-span determination. J Gerontol A Biol Sci Med Sci 2002; 57:B177-88. [PMID: 11983714 DOI: 10.1093/gerona/57.5.b177] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The remarkable progress in understanding the genetic basis of life-span determination in invertebrates indicates that impairments in the insulin-insulin-like growth factor 1 (IGF-1) signaling cascade increase longevity. Similarities among insulin and IGF-1-like signaling pathways in invertebrates and mammals raise the possibility that modifications of these pathways may extend life span in mammals. Investigators using Ames, Snell, and growth hormone receptor knockout models have concluded that decreased growth hormone and IGF-1 are responsible for increased life span. In this review, we critique the dwarf models and, based on multiple endocrine deficiencies and developmental anomalies, conclude that these models may not be sufficient to assess the consequences of growth hormone or IGF-1 deficiency on either biological aging or life span. We attempt to resolve some of these issues by presenting an alternative animal model of growth hormone-IGF-1 deficiency. Finally, we propose an integrated explanation of growth hormone and IGF-1's contribution to the aging phenotype and life-span determination.
Collapse
Affiliation(s)
- Christy S Carter
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157-1083, USA
| | | | | | | | | | | | | |
Collapse
|
44
|
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.
Collapse
Affiliation(s)
- A Joseph D'Ercole
- Department of Pediatrics, Division of Endocrinology, University of North Carolina at Chapel Hill, North Carolina 27599-7220, USA.
| | | | | |
Collapse
|
45
|
Anderson MF, Aberg MAI, Nilsson M, Eriksson PS. Insulin-like growth factor-I and neurogenesis in the adult mammalian brain. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2002; 134:115-22. [PMID: 11947942 DOI: 10.1016/s0165-3806(02)00277-8] [Citation(s) in RCA: 237] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In most brain regions of highly developed mammals, the majority of neurogenesis is terminated soon after birth. However, new neurons are continually generated throughout life in the subventricular zone and the dentate gyrus of the hippocampus. Insulin-like growth factor-I (IGF-I) is a polypeptide hormone that has demonstrated effects on these progenitor cells. IGF-I induces proliferation of isolated progenitors in culture, as well as affecting various aspects of neuronal induction and maturation. Moreover, systemic infusion of IGF-I increases both proliferation and neurogenesis in the adult rat hippocampus, and uptake of serum IGF-I by the brain parenchyma mediates the increase in neurogenesis induced by exercise. Neurogenesis in the adult brain is regulated by many factors including aging, chronic stress, depression and brain injury. Aging is associated with reductions in both hippocampal neurogenesis and IGF-I levels, and administration of IGF-I to old rats increases neurogenesis and reverses cognitive impairments. Similarly, stress and depression also inhibit neurogenesis, possibly via the associated reductions in serotonin or increases in circulating glucocorticoids. As both of these changes have the potential to down regulate IGF-I production by neural cells, stress may inhibit neurogenesis indirectly via downregulation of IGF-I. In contrast, brain injury stimulates neurogenesis, and is associated with upregulation of IGF-I in the brain. Thus, there is a tight correlation between IGF-I and neurogenesis in the adult brain under different conditions. Further studies are needed to clarify whether IGF-I does indeed mediate neurogenesis in these situations.
Collapse
Affiliation(s)
- Michelle F Anderson
- Institute of Clinical Neuroscience, Göteborg University, Blå Stråket 7, Göteborg, Sweden
| | | | | | | |
Collapse
|
46
|
von Bohlen und Halbach O, Walther T, Bader M, Albrecht D. Genetic deletion of angiotensin AT2 receptor leads to increased cell numbers in different brain structures of mice. REGULATORY PEPTIDES 2001; 99:209-16. [PMID: 11384784 DOI: 10.1016/s0167-0115(01)00258-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Angiotensin II (Ang II) is a potent vasoactive peptide and displays growth factor-like properties. Different high-affinity Ang II receptor subtypes (AT1A, AT1B and AT2) have been cloned. They are expressed in various brain structures. Additionally, it has been assumed that Mas could interact directly or indirectly with the renin-angiotensin system. The AT1 receptor mediates pressor and mitogenic effects of Ang II, whereas physiological function and signaling mechanisms of the AT2 receptor remain poorly understood. Recent reports have shown that Ang II could mediate apoptosis through AT2 receptors. Since the AT1A, AT2 and Mas knockout mice provide new tools for uncovering potential actions of Ang II, the cell number in different brain structures of male adult wild-type mice and mice deficient for AT1A, AT2 or Mas was evaluated to get more insight into the role of Ang II in central nervous system development. In nearly all investigated brain structures (cortex, hippocampus, amygdala, thalamus), the cell number was significantly higher in AT2-deficient mice in comparison to wild-type mice. To the contrary, in AT1A-deficient mice the cell number was significantly less than in controls in the lateral geniculate and the medial amygdaloid nucleus. However, cell numbers were not changed in Mas-knockout mice compared to their wild-types. These results show the contrary effects of both angiotensin receptors on cell growth and represent the first demonstration of their action on neuronal cell development evidenced in the adult mouse brain.
Collapse
MESH Headings
- Angiotensin II/deficiency
- Angiotensin II/physiology
- Animals
- Brain/cytology
- Brain/enzymology
- Brain/metabolism
- Brain Chemistry/genetics
- Cell Count
- Gene Deletion
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Neurons/enzymology
- Neurons/metabolism
- Protein-Tyrosine Kinases/deficiency
- Protein-Tyrosine Kinases/genetics
- Proto-Oncogene Mas
- Proto-Oncogene Proteins/deficiency
- Proto-Oncogene Proteins/genetics
- Receptor, Angiotensin, Type 1
- Receptor, Angiotensin, Type 2
- Receptors, Angiotensin/deficiency
- Receptors, Angiotensin/genetics
- Receptors, Angiotensin/physiology
- Receptors, G-Protein-Coupled
Collapse
Affiliation(s)
- O von Bohlen und Halbach
- Johannes Müller Institute of Physiology (Charité), Humboldt University, Tucholskystrasse 2, D-10117, Berlin, Germany.
| | | | | | | |
Collapse
|
47
|
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.
Collapse
|
48
|
Abstract
In several species, including humans, the dentate granule cell layer (GCL) of the hippocampus exhibits neurogenesis throughout adult life. The ability to regulate adult neurogenesis pharmacologically may be of therapeutic value as a mechanism for replacing lost neurons. Insulin-like growth factor-I (IGF-I) is a growth-promoting peptide hormone that has been shown to have neurotrophic properties. The relationship between IGF-I and adult hippocampal neurogenesis is to date unknown. The aim of this study was to investigate the effect of the peripheral administration of IGF-I on cellular proliferation in the dentate subgranular proliferative zone, which contains neuronal progenitor cells, and on the subsequent migration and differentiation of progenitor cells within the GCL. Using bromodeoxyuridine (BrdU) labeling, we found a significant increase of BrdU-immunoreactive progenitors in the GCL after 6 d of peripheral IGF-I administration. To determine the cell fate in progenitor progeny, we characterized the colocalization of BrdU-immunolabeled cells with cell-specific markers. In animals treated with IGF-I for 20 d, BrdU-positive cells increased significantly. Furthermore, the fraction of newly generated neurons in the GCL increased, as evaluated by the neuronal markers Calbindin D(28K), microtubule-associated protein-2, and NeuN. There was no difference in the fraction of newly generated astrocytes. Thus, our results show that peripheral infusion of IGF-I increases progenitor cell proliferation and selectively induces neurogenesis in the progeny of adult neural progenitor cells. This corresponds to a 78 +/- 17% (p < 0.001) increase in the number of new neurons in IGF-I-treated animals compared with controls.
Collapse
|
49
|
Polizzotto MN, Bartlett PF, Turnley AM. Expression of ?suppressor of cytokine signalling? (SOCS) genes in the developing and adult mouse nervous system. J Comp Neurol 2000. [DOI: 10.1002/1096-9861(20000724)423:2<348::aid-cne11>3.0.co;2-w] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|