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Characterization of clostridium botulinum neurotoxin serotype A (BoNT/A) and fibroblast growth factor receptor interactions using novel receptor dimerization assay. Sci Rep 2021; 11:7832. [PMID: 33837264 PMCID: PMC8035261 DOI: 10.1038/s41598-021-87331-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 03/24/2021] [Indexed: 01/03/2023] Open
Abstract
Clostridium botulinum neurotoxin serotype A (BoNT/A) is a potent neurotoxin that serves as an effective therapeutic for several neuromuscular disorders via induction of temporary muscular paralysis. Specific binding and internalization of BoNT/A into neuronal cells is mediated by its binding domain (HC/A), which binds to gangliosides, including GT1b, and protein cell surface receptors, including SV2. Previously, recombinant HC/A was also shown to bind to FGFR3. As FGFR dimerization is an indirect measure of ligand-receptor binding, an FCS & TIRF receptor dimerization assay was developed to measure rHC/A-induced dimerization of fluorescently tagged FGFR subtypes (FGFR1-3) in cells. rHC/A dimerized FGFR subtypes in the rank order FGFR3c (EC50 ≈ 27 nM) > FGFR2b (EC50 ≈ 70 nM) > FGFR1c (EC50 ≈ 163 nM); rHC/A dimerized FGFR3c with similar potency as the native FGFR3c ligand, FGF9 (EC50 ≈ 18 nM). Mutating the ganglioside binding site in HC/A, or removal of GT1b from the media, resulted in decreased dimerization. Interestingly, reduced dimerization was also observed with an SV2 mutant variant of HC/A. Overall, the results suggest that the FCS & TIRF receptor dimerization assay can assess FGFR dimerization with known and novel ligands and support a model wherein HC/A, either directly or indirectly, interacts with FGFRs and induces receptor dimerization.
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Enriched Environment Promotes Adult Hippocampal Neurogenesis through FGFRs. J Neurosci 2021; 41:2899-2910. [PMID: 33637561 DOI: 10.1523/jneurosci.2286-20.2021] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 12/27/2020] [Accepted: 01/07/2021] [Indexed: 12/14/2022] Open
Abstract
The addition of new neurons to existing neural circuits in the adult brain remains of great interest to neurobiology because of its therapeutic implications. The premier model for studying this process has been the hippocampal dentate gyrus in mice, where new neurons are added to mature circuits during adulthood. Notably, external factors such as an enriched environment (EE) and exercise markedly increase hippocampal neurogenesis. Here, we demonstrate that EE acts by increasing fibroblast growth factor receptor (FGFR) function autonomously within neurogenic cells to expand their numbers in adult male and female mice. FGFRs activated by EE signal through their mediators, FGFR substrate (FRS), to induce stem cell proliferation, and through FRS and phospholipase Cγ to increase the number of adult-born neurons, providing a mechanism for how EE promotes adult neurogenesis.SIGNIFICANCE STATEMENT How the environment we live in affects cognition remains poorly understood. In the current study, we explore the mechanism underlying the effects of an enriched environment on the production of new neurons in the adult hippocampal dentate gyrus, a brain area integral in forming new memories. A mechanism is provided for how neural precursor cells in the adult mammalian dentate gyrus respond to an enriched environment to increase their neurogenic output. Namely, an enriched environment acts on stem and progenitor cells by activating fibroblast growth factor receptor signaling through phospholipase Cγ and FGF receptor substrate proteins to expand the pool of precursor cells.
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Lacouture ME, Sibaud V, Anadkat MJ, Kaffenberger B, Leventhal J, Guindon K, Abou‐Alfa G. Dermatologic Adverse Events Associated with Selective Fibroblast Growth Factor Receptor Inhibitors: Overview, Prevention, and Management Guidelines. Oncologist 2021; 26:e316-e326. [PMID: 33021006 PMCID: PMC7873330 DOI: 10.1002/onco.13552] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 09/25/2020] [Indexed: 12/18/2022] Open
Abstract
Fibroblast growth factor receptor (FGFR) tyrosine kinases, which are expressed on the cell membrane, are involved in a wide range of biological functions such as cell proliferation, survival, migration, and differentiation. The identification of FGFR fusions and other alterations in a wide range of solid tumors, including cholangiocarcinoma and bladder cancer, has resulted in the development of several selective FGFR inhibitors for use in these indications, for example, infigratinib, erdafitinib, derazantinib, pemigatinib, and futibatinib. In addition to the typical adverse events associated with tyrosine kinases, the FGFR inhibitors appear to give rise to a number of adverse events affecting the skin. Here we describe these skin events, which include the more common nail adverse events (e.g., onycholysis), palmar-plantar erythrodysesthesia syndrome, and stomatitis, as well as less common reactions such as calciphylaxis. This review aims to provide oncologists with an understanding of these dermatologic events and proposes guidelines for the management of treatment-emergent dermatologic adverse events. Awareness of possible adverse events associated with specific drugs should allow physicians to educate patients as to what to expect and implement effective management plans at the earliest possible opportunity, thereby preventing premature discontinuation while maintaining patient quality of life. IMPLICATIONS FOR PRACTICE: Identification of fibroblast growth factor receptor (FGFR) aberrations in cholangiocarcinoma and bladder cancer led to development of selective FGFR inhibitors for these indications, based on clinical benefit and safety profiles. The most frequent adverse events (AEs) include those affecting skin, hair, and nails, a unique class effect of these agents. These are usually mild to moderate in severity. This work reviewed skin AEs reported with FGFR inhibitors and provides management guidelines for physicians, aiming to increase awareness of skin events and provide effective treatment strategies. Early intervention and effective management may improve treatment adherence, optimize outcomes, and improve quality of life.
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Affiliation(s)
| | - Vincent Sibaud
- Department of Oncodermatology, Institut Universitaire du Cancer Toulouse OncopoleToulouseFrance
| | - Milan J. Anadkat
- Division of Dermatology, Department of Medicine, Washington University School of MedicineSaint LouisMissouriUSA
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FGFR Regulation of Dendrite Elaboration in Adult-born Granule Cells Depends on Intracellular Mediator and Proximity to the Soma. Neuroscience 2020; 453:148-167. [PMID: 33246055 DOI: 10.1016/j.neuroscience.2020.10.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 10/20/2020] [Accepted: 10/21/2020] [Indexed: 01/24/2023]
Abstract
Fibroblast Growth Factor Receptors (FGFRs) play crucial roles in promoting dendrite growth and branching during development. In mice, three FGFR genes, Fgfr1, Fgfr2, and Fgfr3, remain expressed in the adult neurogenic niche of the hippocampal dentate gyrus. However, the function of FGFRs in the dendritic maturation of adult-born neurons remains largely unexplored. Here, using conditional alleles of Fgfr1, Fgfr2, and Fgfr3 as well as Fgfr1 alleles lacking binding sites for Phospholipase-Cγ (PLCγ) and FGF Receptor Substrate (FRS) proteins, we test the requirement for FGFRs in dendritogenesis of adult-born granule cells. We find that deleting all three receptors results in a small decrease in proximal dendrite elaboration. In contrast, specifically mutating Tyr766 in FGFR1 (a PLCγ binding site) in an Fgfr2;Fgfr3 deficient background results in a dramatic increase of overall dendrite elaboration, while blocking FGFR1-FRS signaling causes proximal dendrite deficits and, to a lesser extent than Tyr766 mutants, increases distal dendrite elaboration. These findings reveal unexpectedly complex roles for FGFRs and their intracellular mediators in regulating proximal and distal dendrite elaboration, with the most notable role in suppressing distal elaboration through the PLCγbinding site.
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Grońska-Pęski M, Schachner M, Hébert JM. L1cam curbs the differentiation of adult-born hippocampal neurons. Stem Cell Res 2020; 48:101999. [PMID: 32971459 PMCID: PMC7578921 DOI: 10.1016/j.scr.2020.101999] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 08/19/2020] [Accepted: 09/10/2020] [Indexed: 02/05/2023] Open
Abstract
L1 is an immunoglobulin domain (Ig)-containing protein essential for a wide range of neurodevelopmental processes highly conserved across species from worms to humans. L1 can act as a cell adhesion molecule by binding to other Ig-containing proteins or as a ligand for certain tyrosine kinase receptors such as FGFRs and TRKs, which are required not only during neurodevelopment but also in hippocampal neurogenesis. Yet, the role of L1 itself in adult hippocampal neurogenesis remains unaddressed. Here, we used several Cre-driver lines in mice to conditionally delete a floxed allele of L1cam at different points along the differentiation lineage of new neurons and in surrounding neurons in the adult dentate gyrus of the hippocampus. We found that L1cam deletion in stem/progenitor cells increased: 1) the differentiation of progenitors into new neurons, 2) the complexity of dendritic arbors in immature neurons, and 3) anxiety-related behavior. In addition, deletion of L1cam in neurons leads to an earlier age-related decline in hippocampal neurogenesis. These data suggest that L1 is not only important for normal nervous system development, but also for maintaining certain neural processes in adulthood.
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Affiliation(s)
- Marta Grońska-Pęski
- Departments of Neuroscience and Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Melitta Schachner
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854, USA; Center for Neuroscience, Shantou University Medical College, Shantou, Guangdong 515041, China
| | - Jean M Hébert
- Departments of Neuroscience and Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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Kon E, Calvo-Jiménez E, Cossard A, Na Y, Cooper JA, Jossin Y. N-cadherin-regulated FGFR ubiquitination and degradation control mammalian neocortical projection neuron migration. eLife 2019; 8:47673. [PMID: 31577229 PMCID: PMC6786859 DOI: 10.7554/elife.47673] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Accepted: 10/01/2019] [Indexed: 12/18/2022] Open
Abstract
The functions of FGF receptors (FGFRs) in early development of the cerebral cortex are well established. Their functions in the migration of neocortical projection neurons, however, are unclear. We have found that FGFRs regulate multipolar neuron orientation and the morphological change into bipolar cells necessary to enter the cortical plate. Mechanistically, our results suggest that FGFRs are activated by N-Cadherin. N-Cadherin cell-autonomously binds FGFRs and inhibits FGFR K27- and K29-linked polyubiquitination and lysosomal degradation. Accordingly, FGFRs accumulate and stimulate prolonged Erk1/2 phosphorylation. Neurons inhibited for Erk1/2 are stalled in the multipolar zone. Moreover, Reelin, a secreted protein regulating neuronal positioning, prevents FGFR degradation through N-Cadherin, causing Erk1/2 phosphorylation. These findings reveal novel functions for FGFRs in cortical projection neuron migration, suggest a physiological role for FGFR and N-Cadherin interaction in vivo and identify Reelin as an extracellular upstream regulator and Erk1/2 as downstream effectors of FGFRs during neuron migration.
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Affiliation(s)
- Elif Kon
- Laboratory of Mammalian Development & Cell Biology, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Elisa Calvo-Jiménez
- Laboratory of Mammalian Development & Cell Biology, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Alexia Cossard
- Laboratory of Mammalian Development & Cell Biology, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Youn Na
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Jonathan A Cooper
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Yves Jossin
- Laboratory of Mammalian Development & Cell Biology, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
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Kamatkar N, Levy M, Hébert JM. Development of a Monomeric Inhibitory RNA Aptamer Specific for FGFR3 that Acts as an Activator When Dimerized. MOLECULAR THERAPY-NUCLEIC ACIDS 2019; 17:530-539. [PMID: 31357131 PMCID: PMC6661505 DOI: 10.1016/j.omtn.2019.06.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 06/12/2019] [Accepted: 06/22/2019] [Indexed: 12/11/2022]
Abstract
There have been limited options for people who suffer from fibroblast growth factor receptor (FGFR) signaling disorders. In this study, we developed RNA aptamers specific for FGFR3 as potential therapeutic agents. Using a structured aptamer library, we performed ten rounds of SELEX (systematic evolution of ligands by exponential enrichment) against mouse FGFR3c protein. Using an engineered BaF3 cell line, one aptamer clone from round 6 of the selection inhibited FGF-dependent cell growth with a concentration at which 50% of growth is observed (IC50) of ∼260 nM and bound both mouse and human FGFR3 but not FGFR1 or FGFR2. This inhibitor of FGFR3 signaling (iR3), when dimerized using a template-driven approach, resulted in a functional activator of FGFR3 (aR3). We validated the activity and specificity of iR3 and aR3 on engineered BaF3 cell lines, mouse and human FGFR protein, and primary cultures of neuroepithelial precursor cells.
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Affiliation(s)
- Nachiket Kamatkar
- Departments of Neuroscience and Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| | - Matthew Levy
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| | - Jean M Hébert
- Departments of Neuroscience and Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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Jiang L, Xu J, Jin R, Bai H, Zhang M, Yang S, Zhang X, Zhang X, Han Z, Zeng S. Transcriptomic analysis of chicken cochleae after gentamicin damage and the involvement of four signaling pathways (Notch, FGF, Wnt and BMP) in hair cell regeneration. Hear Res 2018; 361:66-79. [DOI: 10.1016/j.heares.2018.01.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 06/22/2017] [Accepted: 01/06/2018] [Indexed: 10/18/2022]
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Richtsmeier JT. A century of development. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 165:726-740. [PMID: 29574839 PMCID: PMC6007869 DOI: 10.1002/ajpa.23379] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 12/02/2017] [Accepted: 12/09/2017] [Indexed: 12/13/2022]
Affiliation(s)
- Joan T Richtsmeier
- Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania 16802
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10
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Liu S, Marcelin G, Blouet C, Jeong JH, Jo YH, Schwartz GJ, Chua S. A gut-brain axis regulating glucose metabolism mediated by bile acids and competitive fibroblast growth factor actions at the hypothalamus. Mol Metab 2017; 8:37-50. [PMID: 29290621 PMCID: PMC5985052 DOI: 10.1016/j.molmet.2017.12.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 11/27/2017] [Accepted: 12/05/2017] [Indexed: 12/17/2022] Open
Abstract
OBJECTIVE Bile acids have been implicated as important regulators of glucose metabolism via activation of FXR and GPBAR1. We have previously shown that FGF19 can modulate glucose handling by suppressing the activity of hypothalamic AGRP/NPY neurons. As bile acids stimulate the release of FGF19/FGF15 into the circulation, we pursued the potential of bile acids to improve glucose tolerance via a gut-brain axis involving FXR and FGF15/FGF19 within enterocytes and FGF receptors on hypothalamic AGRP/NPY neurons. METHODS A 5-day gavage of taurocholic acid, mirroring our previous protocol of a 5-day FGF19 treatment, was performed. Oral glucose tolerance tests in mice with genetic manipulations of FGF signaling and melanocortin signaling were used to define a gut-brain axis responsive to bile acids. RESULTS The taurocholic acid gavage led to increased serum concentrations of taurocholic acid as well as increases of FGF15 mRNA in the ileum and improved oral glucose tolerance in obese (ob/ob) mice. In contrast, lithocholic acid, an FXR antagonist but a potent agonist for GPBAR1, did not improve glucose tolerance. The positive response to taurocholic acid is dependent upon an intact melanocortinergic system as obese MC4R-null mice or ob/ob mice without AGRP did not show improvements in glucose tolerance after taurocholate gavage. We also tested the FGF receptor isoform necessary for the bile acid response, using AGRP:Fgfr1-/- and AGRP:Fgfr2-/- mice. While the absence of FGFR1 in AGRP/NPY neurons did not alter glucose tolerance after taurocholate gavage, manipulations of Fgfr2 caused bidirectional changes depending upon the experimental model. We hypothesized the existence of an endogenous hypothalamic FGF, most likely FGF17, that acted as a chronic activator of AGRP/NPY neurons. We developed two short peptides based on FGF8 and FGF17 that should antagonize FGF17 action. Both of these peptides improved glucose homeostasis after a 4-day course of central and peripheral injections. Significantly, daily average blood glucose from continuous glucose monitoring was reduced in all tested animals but glucose concentrations remained in the euglycemia range. CONCLUSIONS We have defined a gut-brain axis that regulates glucose metabolism mediated by antagonistic fibroblast growth factors. From the intestine, bile acids stimulate FGF15 secretion, leading to activation of the FGF receptors in hypothalamic AGRP/NPY neurons. FGF receptor intracellular signaling subsequently silences AGRP/NPY neurons, leading to improvements of glucose tolerance that are likely mediated by the autonomic nervous system. Finally, short peptides that antagonize homodimeric FGF receptor signaling within the hypothalamus have beneficial effects on glucose homeostasis without inducing hypoglycemia. These peptides could provide a new mode of regulating glucose metabolism.
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Affiliation(s)
- Shunmei Liu
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Genevieve Marcelin
- INSERM UMR S 1166, ICAN Institute, Faculte de Medecine Pitie-Salpetriere, 91 Boulevard de l'Hopital, 75013 Paris, France
| | - Clemence Blouet
- MRC Metabolic Diseases Unit, Metabolic Research Laboratories, University of Cambridge, Cambridge, United Kingdom
| | - Jae Hoon Jeong
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Young-Hwan Jo
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Gary J Schwartz
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Streamson Chua
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
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FGF-FGFR Mediates the Activity-Dependent Dendritogenesis of Layer IV Neurons during Barrel Formation. J Neurosci 2017; 37:12094-12105. [PMID: 29097598 DOI: 10.1523/jneurosci.1174-17.2017] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Revised: 09/07/2017] [Accepted: 09/27/2017] [Indexed: 01/01/2023] Open
Abstract
Fibroblast growth factors (FGFs) and FGF receptors (FGFRs) are known for their potent effects on cell proliferation/differentiation and cortical patterning in the developing brain. However, little is known regarding the roles of FGFs/FGFRs in cortical circuit formation. Here we show that Fgfr1/2/3 and Fgf7/9/10/22 mRNAs are expressed in the developing primary somatosensory (S1) barrel cortex. Barrel cortex layer IV spiny stellate cells (bSCs) are the primary recipients of ascending sensory information via thalamocortical axons (TCAs). Detail quantification revealed distinctive phases for bSC dendritogenesis: orienting dendrites toward TCAs, adding de novo dendritic segments, and elongating dendritic length, while maintaining dendritic patterns. Deleting Fgfr1/2/3 in bSCs had minimal impact on dendritic polarity but transiently increased the number of dendritic segments. However, 6 d later, FGFR1/2/3 loss of function reduced dendritic branch numbers. These data suggest that FGFs/FGFRs have a role in stabilizing dendritic patterning. Depolarization of cultured mouse cortical neurons upregulated the levels of several Fgf/Fgfr mRNAs within 2 h. In vivo, within 6 h of systemic kainic acid administration at postnatal day 6, mRNA levels of Fgf9, Fgf10, Fgfr2c, and Fgfr3b in S1 cortices were enhanced, and this was accompanied by exuberant dendritogenesis of bSCs by 24 h. Deleting Fgfr1/2/3 abolished kainic acid-induced bSC dendritic overgrowth. Finally, FGF9/10 gain of function also resulted in extensive dendritogenesis. Together, our data suggest that FGFs/FGFRs can be regulated by glutamate transmission to modulate/stabilize bSC dendritic complexity. Both male and female mice were used for our study.SIGNIFICANCE STATEMENT Glutamatergic transmission plays critical roles in cortical circuit formation. Its dysregulation has been proposed as a core factor in the etiology of many neurological diseases. We found that excessive glutamate transmission upregulated mRNA expression of Fgfrs and their ligands Fgfs Deleting Fgfr1/2/3 not only impaired bSC dendritogenesis but also abolished glutamate transmission-induced dendritic overgrowth. Overexpressing FGF9 or FGF10 in cortical glutamatergic neurons results in excessive dendritic outgrowth within 24 h, resembling the changes induced by excessive glutamate transmission. Our findings provide strong evidence for the physiological role of fibroblast growth factors (FGFs) and FGF receptors (FGFRs) in establishing and maintaining cortical circuits. Perturbing the expression levels of FGFs/FGFRs by excessive glutamatergic neurotransmission could lead to abnormal neuronal circuits, which may contribute to neurological and psychiatric disease.
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12
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Turrero García M, Harwell CC. Radial glia in the ventral telencephalon. FEBS Lett 2017; 591:3942-3959. [PMID: 28862741 DOI: 10.1002/1873-3468.12829] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 08/23/2017] [Accepted: 08/24/2017] [Indexed: 12/31/2022]
Abstract
The ventral telencephalon is the developmental origin of the basal ganglia and the source of neuronal and glial cells that integrate into developing circuits in other areas of the brain. Radial glia in the embryonic subpallium give rise to an enormous diversity of mature cell types, either directly or through other transit-amplifying progenitors. Here, we review current knowledge about these subpallial neural stem cells and their progeny, focusing on the period of neurogenesis. We describe their cell biological features and the extrinsic and intrinsic molecular codes that guide their fate specification in defined temporal and spatial sequences. We also discuss the role of clonal lineage in the organization and specification of mature neurons.
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Affiliation(s)
| | - Corey C Harwell
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
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13
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Motch Perrine SM, Stecko T, Neuberger T, Jabs EW, Ryan TM, Richtsmeier JT. Integration of Brain and Skull in Prenatal Mouse Models of Apert and Crouzon Syndromes. Front Hum Neurosci 2017; 11:369. [PMID: 28790902 PMCID: PMC5525342 DOI: 10.3389/fnhum.2017.00369] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 06/29/2017] [Indexed: 01/23/2023] Open
Abstract
The brain and skull represent a complex arrangement of integrated anatomical structures composed of various cell and tissue types that maintain structural and functional association throughout development. Morphological integration, a concept developed in vertebrate morphology and evolutionary biology, describes the coordinated variation of functionally and developmentally related traits of organisms. Syndromic craniosynostosis is characterized by distinctive changes in skull morphology and perceptible, though less well studied, changes in brain structure and morphology. Using mouse models for craniosynostosis conditions, our group has precisely defined how unique craniosynostosis causing mutations in fibroblast growth factor receptors affect brain and skull morphology and dysgenesis involving coordinated tissue-specific effects of these mutations. Here we examine integration of brain and skull in two mouse models for craniosynostosis: one carrying the FGFR2c C342Y mutation associated with Pfeiffer and Crouzon syndromes and a mouse model carrying the FGFR2 S252W mutation, one of two mutations responsible for two-thirds of Apert syndrome cases. Using linear distances estimated from three-dimensional coordinates of landmarks acquired from dual modality imaging of skull (high resolution micro-computed tomography and magnetic resonance microscopy) of mice at embryonic day 17.5, we confirm variation in brain and skull morphology in Fgfr2cC342Y/+ mice, Fgfr2+/S252W mice, and their unaffected littermates. Mutation-specific variation in neural and cranial tissue notwithstanding, patterns of integration of brain and skull differed only subtly between mice carrying either the FGFR2c C342Y or the FGFR2 S252W mutation and their unaffected littermates. However, statistically significant and substantial differences in morphological integration of brain and skull were revealed between the two mutant mouse models, each maintained on a different strain. Relative to the effects of disease-associated mutations, our results reveal a stronger influence of the background genome on patterns of brain-skull integration and suggest robust genetic, developmental, and evolutionary relationships between neural and skeletal tissues of the head.
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Affiliation(s)
- Susan M Motch Perrine
- Department of Anthropology, Pennsylvania State UniversityUniversity Park, PA, United States
| | - Tim Stecko
- Center for Quantitative Imaging, Penn State Institutes for Energy and the Environment, Pennsylvania State UniversityUniversity Park, PA, United States
| | - Thomas Neuberger
- High Field MRI Facility, Huck Institutes of the Life Sciences, Pennsylvania State UniversityUniversity Park, PA, United States.,Department of Bioengineering, Pennsylvania State UniversityUniversity Park, PA, United States
| | - Ethylin W Jabs
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount SinaiNew York, NY, United States
| | - Timothy M Ryan
- Department of Anthropology, Pennsylvania State UniversityUniversity Park, PA, United States.,Center for Quantitative Imaging, Penn State Institutes for Energy and the Environment, Pennsylvania State UniversityUniversity Park, PA, United States
| | - Joan T Richtsmeier
- Department of Anthropology, Pennsylvania State UniversityUniversity Park, PA, United States
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14
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Collette JC, Choubey L, Smith KM. -Glial and stem cell expression of murine Fibroblast Growth Factor Receptor 1 in the embryonic and perinatal nervous system. PeerJ 2017; 5:e3519. [PMID: 28674667 PMCID: PMC5493973 DOI: 10.7717/peerj.3519] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 06/08/2017] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Fibroblast growth factors (FGFs) and their receptors (FGFRs) are involved in the development and function of multiple organs and organ systems, including the central nervous system (CNS). FGF signaling via FGFR1, one of the three FGFRs expressed in the CNS, stimulates proliferation of stem cells during prenatal and postnatal neurogenesis and participates in regulating cell-type ratios in many developing regions of the brain. Anomalies in FGFR1 signaling have been implicated in certain neuropsychiatric disorders. Fgfr1 expression has been shown, via in situ hybridization, to vary spatially and temporally throughout embryonic and postnatal development of the brain. However, in situ hybridization lacks sufficient resolution to identify which cell-types directly participate in FGF signaling. Furthermore, because antibodies raised against FGFR1 commonly cross-react with other members of the FGFR family, immunocytochemistry is not alone sufficient to accurately document Fgfr1 expression. Here, we elucidate the identity of Fgfr1 expressing cells in both the embryonic and perinatal mouse brain. METHODS To do this, we utilized a tgFGFR1-EGFPGP338Gsat BAC line (tgFgfr1-EGFP+) obtained from the GENSAT project. The tgFgfr1-EGFP+ line expresses EGFP under the control of a Fgfr1 promoter, thereby causing cells endogenously expressing Fgfr1 to also present a positive GFP signal. Through simple immunostaining using GFP antibodies and cell-type specific antibodies, we were able to accurately determine the cell-type of Fgfr1 expressing cells. RESULTS This technique revealed Fgfr1 expression in proliferative zones containing BLBP+ radial glial stem cells, such as the cortical and hippocampal ventricular zones, and cerebellar anlage of E14.5 mice, in addition to DCX+ neuroblasts. Furthermore, our data reveal Fgfr1 expression in proliferative zones containing BLBP+ cells of the anterior midline, hippocampus, cortex, hypothalamus, and cerebellum of P0.5 mice, in addition to the early-formed GFAP+ astrocytes of the anterior midline. DISCUSSION Understanding when during development and where Fgfr1 is expressed is critical to improving our understanding of its function during neurodevelopment as well as in the mature CNS. This information may one day provide an avenue of discovery towards understanding the involvement of aberrant FGF signaling in neuropsychiatric disorders.
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Affiliation(s)
- Jantzen C Collette
- Department of Biology, University of Louisiana at Lafayette, Lafayette, LA, United States of America
| | - Lisha Choubey
- Department of Biology, University of Louisiana at Lafayette, Lafayette, LA, United States of America
| | - Karen Müller Smith
- Department of Biology, University of Louisiana at Lafayette, Lafayette, LA, United States of America
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FGF-Dependent, Context-Driven Role for FRS Adapters in the Early Telencephalon. J Neurosci 2017; 37:5690-5698. [PMID: 28483978 DOI: 10.1523/jneurosci.2931-16.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 04/07/2017] [Accepted: 04/25/2017] [Indexed: 01/20/2023] Open
Abstract
FGF signaling, an important component of intercellular communication, is required in many tissues throughout development to promote diverse cellular processes. Whether FGF receptors (FGFRs) accomplish such varied tasks in part by activating different intracellular transducers in different contexts remains unclear. Here, we used the developing mouse telencephalon as an example to study the role of the FRS adapters FRS2 and FRS3 in mediating the functions of FGFRs. Using tissue-specific and germline mutants, we examined the requirement of Frs genes in two FGFR-dependent processes. We found that Frs2 and Frs3 are together required for the differentiation of a subset of medial ganglionic eminence (MGE)-derived neurons, but are dispensable for the survival of early telencephalic precursor cells, in which any one of three FGFRs (FGFR1, FGFR2, or FGFR3) is sufficient for survival. Although FRS adapters are dispensable for ERK-1/2 activation, they are required for AKT activation within the subventricular zone of the developing MGE. Using an FRS2,3-binding site mutant of Fgfr1, we established that FRS adapters are necessary for mediating most or all FGFR1 signaling, not only in MGE differentiation, but also in cell survival, implying that other adapters mediate at least in part the signaling from FGFR2 and FGFR3. Our study provides an example of a contextual role for an intracellular transducer and contributes to our understanding of how FGF signaling plays diverse developmental roles.SIGNIFICANCE STATEMENT FGFs promote a range of developmental processes in many developing tissues and at multiple developmental stages. The mechanisms underlying this multifunctionality remain poorly defined in vivo Using telencephalon development as an example, we show here that FRS adapters exhibit some selectivity in their requirement for mediating FGF receptor (FGFR) signaling and activating downstream mediators that depend on the developmental process, with a requirement in neuronal differentiation but not cell survival. Differential engagement of FRS and non-FRS intracellular adapters downstream of FGFRs could therefore in principle explain how FGFs play several distinct roles in other developing tissues and developmental stages.
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16
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Choubey L, Collette JC, Smith KM. Quantitative assessment of fibroblast growth factor receptor 1 expression in neurons and glia. PeerJ 2017; 5:e3173. [PMID: 28439461 PMCID: PMC5398288 DOI: 10.7717/peerj.3173] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 03/13/2017] [Indexed: 01/23/2023] Open
Abstract
Background Fibroblast growth factors (FGFs) and their receptors (FGFRs) have numerous functions in the developing and adult central nervous system (CNS). For example, the FGFR1 receptor is important for proliferation and fate specification of radial glial cells in the cortex and hippocampus, oligodendrocyte proliferation and regeneration, midline glia morphology and soma translocation, Bergmann glia morphology, and cerebellar morphogenesis. In addition, FGFR1 signaling in astrocytes is required for postnatal maturation of interneurons expressing parvalbumin (PV). FGFR1 is implicated in synapse formation in the hippocampus, and alterations in the expression of Fgfr1 and its ligand, Fgf2 accompany major depression. Understanding which cell types express Fgfr1 during development may elucidate its roles in normal development of the brain as well as illuminate possible causes of certain neuropsychiatric disorders. Methods Here, we used a BAC transgenic reporter line to trace Fgfr1 expression in the developing postnatal murine CNS. The specific transgenic line employed was created by the GENSAT project, tgFGFR1-EGFPGP338Gsat, and includes a gene encoding enhanced green fluorescent protein (EGFP) under the regulation of the Fgfr1 promoter, to trace Fgfr1 expression in the developing CNS. Unbiased stereological counts were performed for several cell types in the cortex and hippocampus. Results This model reveals that Fgfr1 is primarily expressed in glial cells, in both astrocytes and oligodendrocytes, along with some neurons. Dual labeling experiments indicate that the proportion of GFP+ (Fgfr1+) cells that are also GFAP+ increases from postnatal day 7 (P7) to 1 month, illuminating dynamic changes in Fgfr1 expression during postnatal development of the cortex. In postnatal neurogenic areas, GFP expression was also observed in SOX2, doublecortin (DCX), and brain lipid-binding protein (BLBP) expressing cells. Fgfr1 is also highly expressed in DCX positive cells of the dentate gyrus (DG), but not in the rostral migratory stream. Fgfr1 driven GFP was also observed in tanycytes and GFAP+ cells of the hypothalamus, as well as in Bergmann glia and astrocytes of the cerebellum. Conclusions The tgFGFR1-EGFPGP338Gsat mouse model expresses GFP that is congruent with known functions of FGFR1, including hippocampal development, glial cell development, and stem cell proliferation. Understanding which cell types express Fgfr1 may elucidate its role in neuropsychiatric disorders and brain development.
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Affiliation(s)
- Lisha Choubey
- Department of Biology, University of Louisiana at Lafayette, United States of America
| | - Jantzen C Collette
- Department of Biology, University of Louisiana at Lafayette, United States of America
| | - Karen Müller Smith
- Department of Biology, University of Louisiana at Lafayette, United States of America
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17
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Lee S, Jeong HS, Cho HH. Atoh1 as a Coordinator of Sensory Hair Cell Development and Regeneration in the Cochlea. Chonnam Med J 2017; 53:37-46. [PMID: 28184337 PMCID: PMC5299128 DOI: 10.4068/cmj.2017.53.1.37] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 09/22/2016] [Accepted: 09/23/2016] [Indexed: 12/18/2022] Open
Abstract
Cochlear sensory hair cells (HCs) are crucial for hearing as mechanoreceptors of the auditory systems. Clarification of transcriptional regulation for the cochlear sensory HC development is crucial for the improvement of cell replacement therapies for hearing loss. Transcription factor Atoh1 is the key player during HC development and regeneration. In this review, we will focus on Atoh1 and its related signaling pathways (Notch, fibroblast growth factor, and Wnt/β-catenin signaling) involved in the development of cochlear sensory HCs. We will also discuss the potential applicability of these signals for the induction of HC regeneration.
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Affiliation(s)
- Sungsu Lee
- Department of Otolaryngology-Head and Neck Surgery, Chonnam National University Hospital, Chonnam National University Medical School, Gwangju, Korea.; Research Institute of Medical Sciences, Chonnam National University, Gwangju, Korea
| | - Han-Seong Jeong
- Research Institute of Medical Sciences, Chonnam National University, Gwangju, Korea.; Department of Physiology, Chonnam National University Medical School, Gwangju, Korea
| | - Hyong-Ho Cho
- Department of Otolaryngology-Head and Neck Surgery, Chonnam National University Hospital, Chonnam National University Medical School, Gwangju, Korea.; Research Institute of Medical Sciences, Chonnam National University, Gwangju, Korea
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18
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Karpinski BA, Bryan CA, Paronett EM, Baker JL, Fernandez A, Horvath A, Maynard TM, Moody SA, LaMantia AS. A cellular and molecular mosaic establishes growth and differentiation states for cranial sensory neurons. Dev Biol 2016; 415:228-241. [PMID: 26988119 DOI: 10.1016/j.ydbio.2016.03.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 02/02/2016] [Accepted: 03/13/2016] [Indexed: 02/06/2023]
Abstract
We compared apparent origins, cellular diversity and regulation of initial axon growth for differentiating cranial sensory neurons. We assessed the molecular and cellular composition of the developing olfactory and otic placodes, and cranial sensory ganglia to evaluate contributions of ectodermal placode versus neural crest at each site. Special sensory neuron populations-the olfactory and otic placodes, as well as those in vestibulo-acoustic ganglion- are entirely populated with cells expressing cranial placode-associated, rather than neural crest-associated markers. The remaining cranial sensory ganglia are a mosaic of cells that express placode-associated as well as neural crest-associated markers. We found two distinct populations of neural crest in the cranial ganglia: the first, as expected, is labeled by Wnt1:Cre mediated recombination. The second is not labeled by Wnt1:Cre recombination, and expresses both Sox10 and FoxD3. These populations-Wnt1:Cre recombined, and Sox10/Foxd3-expressing- are proliferatively distinct from one another. Together, the two neural crest-associated populations are substantially more proliferative than their placode-associated counterparts. Nevertheless, the apparently placode- and neural crest-associated populations are similarly sensitive to altered signaling that compromises cranial morphogenesis and differentiation. Acute disruption of either Fibroblast growth factor (Fgf) or Retinoic acid (RA) signaling alters axon growth and cell death, but does not preferentially target any of the three distinct populations. Apparently, mosaic derivation and diversity of precursors and early differentiating neurons, modulated uniformly by local signals, supports early cranial sensory neuron differentiation and growth.
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Affiliation(s)
- Beverly A Karpinski
- Department of Pharmacology and Physiology, The George Washington University, School of Medicine and Health Sciences, Washington DC, USA; Department of Anatomy and Regenerative Biology, The George Washington University, School of Medicine and Health Sciences, Washington DC, USA; The GW Institute for Neuroscience, The George Washington University, School of Medicine and Health Sciences, Washington DC, USA.
| | - Corey A Bryan
- Department of Pharmacology and Physiology, The George Washington University, School of Medicine and Health Sciences, Washington DC, USA; The GW Institute for Neuroscience, The George Washington University, School of Medicine and Health Sciences, Washington DC, USA.
| | - Elizabeth M Paronett
- Department of Pharmacology and Physiology, The George Washington University, School of Medicine and Health Sciences, Washington DC, USA; The GW Institute for Neuroscience, The George Washington University, School of Medicine and Health Sciences, Washington DC, USA.
| | - Jennifer L Baker
- Center for the Advanced Study of Human Paleobiology, The George Washington University, School of Medicine and Health Sciences, Washington DC, USA.
| | - Alejandra Fernandez
- Department of Pharmacology and Physiology, The George Washington University, School of Medicine and Health Sciences, Washington DC, USA; The GW Institute for Neuroscience, The George Washington University, School of Medicine and Health Sciences, Washington DC, USA.
| | - Anelia Horvath
- Department of Pharmacology and Physiology, The George Washington University, School of Medicine and Health Sciences, Washington DC, USA; The GW Institute for Neuroscience, The George Washington University, School of Medicine and Health Sciences, Washington DC, USA.
| | - Thomas M Maynard
- Department of Pharmacology and Physiology, The George Washington University, School of Medicine and Health Sciences, Washington DC, USA; The GW Institute for Neuroscience, The George Washington University, School of Medicine and Health Sciences, Washington DC, USA.
| | - Sally A Moody
- Department of Anatomy and Regenerative Biology, The George Washington University, School of Medicine and Health Sciences, Washington DC, USA; The GW Institute for Neuroscience, The George Washington University, School of Medicine and Health Sciences, Washington DC, USA.
| | - Anthony-S LaMantia
- Department of Pharmacology and Physiology, The George Washington University, School of Medicine and Health Sciences, Washington DC, USA; The GW Institute for Neuroscience, The George Washington University, School of Medicine and Health Sciences, Washington DC, USA.
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19
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Alshammari MA, Alshammari TK, Nenov MN, Scala F, Laezza F. Fibroblast Growth Factor 14 Modulates the Neurogenesis of Granule Neurons in the Adult Dentate Gyrus. Mol Neurobiol 2015; 53:7254-7270. [PMID: 26687232 DOI: 10.1007/s12035-015-9568-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 11/29/2015] [Indexed: 11/25/2022]
Abstract
Adult neurogenesis, the production of mature neurons from progenitor cells in the adult mammalian brain, is linked to the etiology of neurodegenerative and psychiatric disorders. However, a thorough understanding of the molecular elements at the base of adult neurogenesis remains elusive. Here, we provide evidence for a previously undescribed function of fibroblast growth factor 14 (FGF14), a brain disease-associated factor that controls neuronal excitability and synaptic plasticity, in regulating adult neurogenesis in the dentate gyrus (DG). We found that FGF14 is dynamically expressed in restricted subtypes of sex determining region Y-box 2 (Sox2)-positive and doublecortin (DCX)-positive neural progenitors in the DG. Bromodeoxyuridine (BrdU) incorporation studies and confocal imaging revealed that genetic deletion of Fgf14 in Fgf14 -/- mice leads to a significant change in the proportion of proliferating and immature and mature newly born adult granule cells. This results in an increase in the late immature and early mature population of DCX and calretinin (CR)-positive neurons. Electrophysiological extracellular field recordings showed reduced minimal threshold response and impaired paired-pulse facilitation at the perforant path to DG inputs in Fgf14 -/- compared to Fgf14 +/+ mice, supporting disrupted synaptic connectivity as a correlative read-out to impaired neurogenesis. These new insights into the biology of FGF14 in neurogenesis shed light into the signaling pathways associated with disrupted functions in complex brain diseases.
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Affiliation(s)
- Musaad A Alshammari
- Pharmacology and Toxicology Graduate Program, The University of Texas Medical Branch, Galveston, TX, USA
- Graduate Studies Abroad Program, King Saud University, Riyadh, Saudi Arabia
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Medical Research Building 7.102B, 301 University Boulevard, Galveston, TX, 77555, USA
| | - Tahani K Alshammari
- Pharmacology and Toxicology Graduate Program, The University of Texas Medical Branch, Galveston, TX, USA
- Graduate Studies Abroad Program, King Saud University, Riyadh, Saudi Arabia
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Medical Research Building 7.102B, 301 University Boulevard, Galveston, TX, 77555, USA
| | - Miroslav N Nenov
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Medical Research Building 7.102B, 301 University Boulevard, Galveston, TX, 77555, USA
| | - Federico Scala
- Biophysics Graduate Program, Institute of Human Physiology, Università Cattolica, Rome, Italy
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Medical Research Building 7.102B, 301 University Boulevard, Galveston, TX, 77555, USA
| | - Fernanda Laezza
- Mitchell Center for Neurodegenerative Diseases, The University of Texas Medical Branch, Galveston, TX, USA.
- Center for Addiction Research, The University of Texas Medical Branch, Galveston, TX, USA.
- Center for Biomedical Engineering, The University of Texas Medical Branch, Galveston, TX, USA.
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Medical Research Building 7.102B, 301 University Boulevard, Galveston, TX, 77555, USA.
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20
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Kubanov AA, Gallyamova YUA, Selezneva OA. Role of peptide growth factors in the rhythm of change hair. VESTNIK DERMATOLOGII I VENEROLOGII 2015. [DOI: 10.25208/0042-4609-2015-91-3-54-61] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
The article presents current data on the role growth factors play in hair physiology. Based on a review of literature, the authors described the role growth factors play for initiating, suppressing the growth and differentiating hair follicles. According to them, each morphologic development stage of hair follicles is characterized by its own factor expression pattern. Referring to experimental and clinical studies, the authors describe the role some growth factors play for mechanisms promoting the development of androgynous and focal alopecia.
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21
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Zhang W, Johnson JI, Tsai PS. Fgf8-Deficient Mice Compensate for Reduced GnRH Neuronal Population and Exhibit Normal Testicular Function. Front Endocrinol (Lausanne) 2015; 6:151. [PMID: 26441841 PMCID: PMC4585285 DOI: 10.3389/fendo.2015.00151] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 09/07/2015] [Indexed: 11/13/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) is critical for the onset and maintenance of reproduction in vertebrates. The development of GnRH neurons is highly dependent on fibroblast growth factor (Fgf) signaling. Mice with a hypomorphic Fgf8 allele (Fgf8 Het) exhibited a ~50% reduction in GnRH neuron number at birth. Female Fgf8 Het mice were fertile but showed significantly delayed puberty. However, it was unclear if these mice suffered additional loss of GnRH neurons after birth, and if male Fgf8 Het mice had normal pubertal transition and testicular function. In this study, we examined postnatal GnRH neuron number and hypothalamic GnRH content in Fgf8 Het mice from birth to 120 days of age. Further, we examined seminal vesicle and testicular growth, testicular histology, and circulating luteinizing hormone (LH) around and after pubertal transition. Our results showed that GnRH neuron numbers were significantly and consistently reduced in Fgf8 Het mice of both sexes in all ages examined, suggesting these animals were born with an inherently defective GnRH system, and no further postnatal loss of GnRH neurons had occurred. Despite an innately compromised GnRH system, male and female Fgf8 mice exhibited normal levels of immunoassayable hypothalamic GnRH peptide at all ages examined except on 60 days of age, suggesting increased GnRH synthesis or reduced turnover as a compensatory mechanism. Fgf8 Het males also had normal seminal vesicle and testicular mass/body mass ratios, testicular histology, and circulating LH. Overall, our data speak to the extraordinary ability of a GnRH system permanently compromised by developmental defect to overcome pre-existing deficiencies to ensure pubertal progression and reproduction.
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Affiliation(s)
- Wei Zhang
- Department of Integrative Physiology, Center for Neuroscience, University of Colorado Boulder, Boulder, CO, USA
| | - Joshua I. Johnson
- Department of Integrative Physiology, Center for Neuroscience, University of Colorado Boulder, Boulder, CO, USA
| | - Pei-San Tsai
- Department of Integrative Physiology, Center for Neuroscience, University of Colorado Boulder, Boulder, CO, USA
- *Correspondence: Pei-San Tsai, Department of Integrative Physiology, University of Colorado Boulder, 114 Clare Small, Boulder, CO 80309-0354, USA,
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22
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Haupaix N, Abitua PB, Sirour C, Yasuo H, Levine M, Hudson C. Ephrin-mediated restriction of ERK1/2 activity delimits the number of pigment cells in the Ciona CNS. Dev Biol 2014; 394:170-80. [PMID: 25062608 DOI: 10.1016/j.ydbio.2014.07.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 07/04/2014] [Accepted: 07/10/2014] [Indexed: 12/31/2022]
Abstract
Recent evidence suggests that ascidian pigment cells are related to neural crest-derived melanocytes of vertebrates. Using live-imaging, we determine a revised cell lineage of the pigment cells in Ciona intestinalis embryos. The neural precursors undergo successive rounds of anterior-posterior (A-P) oriented cell divisions, starting at the blastula 64-cell stage. A previously unrecognized fourth A-P oriented cell division in the pigment cell lineage leads to the generation of the post-mitotic pigment cell precursors. We provide evidence that MEK/ERK signals are required for pigment cell specification until approximately 30min after the final cell division has taken place. Following each of the four A-P oriented cell divisions, ERK1/2 is differentially activated in the posterior sister cells, into which the pigment cell lineage segregates. Eph/ephrin signals are critical during the third A-P oriented cell division to spatially restrict ERK1/2 activation to the posterior daughter cell. Targeted inhibition of Eph/ephrin signals results in, at neurula stages, anterior expansion of both ERK1/2 activation and a pigment cell lineage marker and subsequently, at larval stages, supernumerary pigment cells. We discuss the implications of these findings with respect to the evolution of the vertebrate neural crest.
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Affiliation(s)
- Nicolas Haupaix
- CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France; Sorbonne Universités, UPMC Univ Paris 06, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France; Université de Nice Sophia Antipolis, Nice, France
| | - Philip B Abitua
- Center for Integrative Genomics, Division of Genetics, Genomics and Development, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Cathy Sirour
- CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France; Sorbonne Universités, UPMC Univ Paris 06, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France
| | - Hitoyoshi Yasuo
- CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France; Sorbonne Universités, UPMC Univ Paris 06, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France
| | - Michael Levine
- Center for Integrative Genomics, Division of Genetics, Genomics and Development, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Clare Hudson
- CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France; Sorbonne Universités, UPMC Univ Paris 06, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France.
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Paldi A. Effects of the in vitro manipulation of stem cells: epigenetic mechanisms as mediators of induced metabolic fluctuations. Epigenomics 2013; 5:429-37. [PMID: 23895655 DOI: 10.2217/epi.13.35] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The increasing popularity of stem cells in life science research has at least two major causes. On one hand, the study of stem cells may provide insights into one of the major secrets of biology: the mechanisms of cell differentiation. On the other hand, stem cells are potentially promising tools for regenerative therapy. The understanding of how environmental stimuli are translated into phenotypic differentiation through gene expression changes and how the same stimuli at the same time may perturb the normal process of cellular differentiation, growth and maintenance is a central issue for fundamental research but is also essential for the development of efficient and safe procedures for therapeutic use. This article assembles the known facts, as pieces of a puzzle, into a coherent picture around the idea of why stem cells are so sensitive to their culture environment and what practical consequences this implies.
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Affiliation(s)
- András Paldi
- Ecole Pratique des Hautes Etudes, INSERM U951, Genethon 1bis rue de l'Internationale 91002 Evry, France.
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24
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Simonis N, Migeotte I, Lambert N, Perazzolo C, de Silva DC, Dimitrov B, Heinrichs C, Janssens S, Kerr B, Mortier G, Van Vliet G, Lepage P, Casimir G, Abramowicz M, Smits G, Vilain C. FGFR1 mutations cause Hartsfield syndrome, the unique association of holoprosencephaly and ectrodactyly. J Med Genet 2013; 50:585-92. [PMID: 23812909 PMCID: PMC3756455 DOI: 10.1136/jmedgenet-2013-101603] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Background Harstfield syndrome is the rare and unique association of holoprosencephaly (HPE) and ectrodactyly, with or without cleft lip and palate, and variable additional features. All the reported cases occurred sporadically. Although several causal genes of HPE and ectrodactyly have been identified, the genetic cause of Hartsfield syndrome remains unknown. We hypothesised that a single key developmental gene may underlie the co-occurrence of HPE and ectrodactyly. Methods We used whole exome sequencing in four isolated cases including one case-parents trio, and direct Sanger sequencing of three additional cases, to investigate the causative variants in Hartsfield syndrome. Results We identified a novel FGFR1 mutation in six out of seven patients. Affected residues are highly conserved and are located in the extracellular binding domain of the receptor (two homozygous mutations) or the intracellular tyrosine kinase domain (four heterozygous de novo variants). Strikingly, among the six novel mutations, three are located in close proximity to the ATP's phosphates or the coordinating magnesium, with one position required for kinase activity, and three are adjacent to known mutations involved in Kallmann syndrome plus other developmental anomalies. Conclusions Dominant or recessive FGFR1 mutations are responsible for Hartsfield syndrome, consistent with the known roles of FGFR1 in vertebrate ontogeny and conditional Fgfr1-deficient mice. Our study shows that, in humans, lack of accurate FGFR1 activation can disrupt both brain and hand/foot midline development, and that FGFR1 loss-of-function mutations are responsible for a wider spectrum of clinical anomalies than previously thought, ranging in severity from seemingly isolated hypogonadotropic hypogonadism, through Kallmann syndrome with or without additional features, to Hartsfield syndrome at its most severe end.
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Affiliation(s)
- Nicolas Simonis
- Laboratoire de Bioinformatique des Génomes et des Réseaux (BiGRe), Université Libre de Bruxelles (ULB), Brussels, Belgium
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Hébert JM. Only scratching the cell surface: extracellular signals in cerebrum development. Curr Opin Genet Dev 2013; 23:470-4. [PMID: 23669550 DOI: 10.1016/j.gde.2013.04.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 04/03/2013] [Indexed: 01/01/2023]
Abstract
Numerous roles have been identified for extracellular signals such as Fibroblast Growth Factors (FGFs), Transforming Growth Factor-βs (TGFβs), Wingless-Int proteins (WNTs), and Sonic Hedgehog (SHH) in assigning fates to cells during development of the cerebrum. However, several fundamental questions remain largely unexplored. First, how does the same extracellular signal instruct precursor cells in different locations or at different stages to adopt distinct fates? And second, how does a precursor cell integrate multiple signals to adopt a specific fate? Answers to these questions require knowing the mechanisms that underlie each cell type's competence to respond to certain extracellular signals. This brief review provides illustrative examples of potential mechanisms that begin to bridge the gap between cell surface and cell fate during cerebrum development.
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Affiliation(s)
- Jean M Hébert
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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Richtsmeier JT, Flaherty K. Hand in glove: brain and skull in development and dysmorphogenesis. Acta Neuropathol 2013; 125:469-89. [PMID: 23525521 PMCID: PMC3652528 DOI: 10.1007/s00401-013-1104-y] [Citation(s) in RCA: 146] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 02/28/2013] [Accepted: 03/02/2013] [Indexed: 01/02/2023]
Abstract
The brain originates relatively early in development from differentiated ectoderm that forms a hollow tube and takes on an exceedingly complex shape with development. The skull is made up of individual bony elements that form from neural crest- and mesoderm-derived mesenchyme that unite to provide support and protection for soft tissues and spaces of the head. The meninges provide a protective and permeable membrane between brain and skull. Across evolutionary and developmental time, dynamic changes in brain and skull shape track one another so that their integration is evidenced in two structures that fit soundly regardless of changes in biomechanical and physiologic functions. Evidence for this tight correspondence is also seen in diseases of the craniofacial complex that are often classified as diseases of the skull (e.g., craniosynostosis) or diseases of the brain (e.g., holoprosencephaly) even when both tissues are affected. Our review suggests a model that links brain and skull morphogenesis through coordinated integration of signaling pathways (e.g., FGF, TGFβ, Wnt) via processes that are not currently understood, perhaps involving the meninges. Differences in the earliest signaling of biological structure establish divergent designs that will be enhanced during morphogenesis. Signaling systems that pattern the developing brain are also active in patterning required for growth and assembly of the skull and some members of these signaling families have been indicated as causal for craniofacial diseases. Because cells of early brain and skull are sensitive to similar signaling families, variation in the strength or timing of signals or shifts in patterning boundaries that affect one system (neural or skull) could also affect the other system and appropriate co-adjustments in development would be made. Interactions of these signaling systems and of the tissues that they pattern are fundamental to the consistent but labile functional and structural association of brain and skull conserved over evolutionary time obvious in the study of development and disease.
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Affiliation(s)
- Joan T Richtsmeier
- Department of Anthropology, Pennsylvania State University, 409 Carpenter Building, University Park, PA 16802, USA.
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Martínez-Abadías N, Holmes G, Pankratz T, Wang Y, Zhou X, Jabs EW, Richtsmeier JT. From shape to cells: mouse models reveal mechanisms altering palate development in Apert syndrome. Dis Model Mech 2013; 6:768-79. [PMID: 23519026 PMCID: PMC3634659 DOI: 10.1242/dmm.010397] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Apert syndrome is a congenital disorder characterized by severe skull malformations and caused by one of two missense mutations, S252W and P253R, on fibroblast growth factor receptor 2 (FGFR2). The molecular bases underlying differential Apert syndrome phenotypes are still poorly understood and it is unclear why cleft palate is more frequent in patients carrying the S252W mutation. Taking advantage of Apert syndrome mouse models, we performed a novel combination of morphometric, histological and immunohistochemical analyses to precisely quantify distinct palatal phenotypes in Fgfr2+/S252W and Fgfr2+/P253R mice. We localized regions of differentially altered FGF signaling and assessed local cell patterns to establish a baseline for understanding the differential effects of these two Fgfr2 mutations. Palatal suture scoring and comparative 3D shape analysis from high resolution μCT images of 120 newborn mouse skulls showed that Fgfr2+/S252W mice display relatively more severe palate dysmorphologies, with contracted and more separated palatal shelves, a greater tendency to fuse the maxillary-palatine sutures and aberrant development of the inter-premaxillary suture. These palatal defects are associated with suture-specific patterns of abnormal cellular proliferation, differentiation and apoptosis. The posterior region of the developing palate emerges as a potential target for therapeutic strategies in clinical management of cleft palate in Apert syndrome patients.
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Affiliation(s)
- Neus Martínez-Abadías
- Department of Anthropology, Pennsylvania State University, 409 Carpenter Building, University Park, PA 16802, USA
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28
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Martínez-Abadías N, Motch SM, Pankratz TL, Wang Y, Aldridge K, Jabs EW, Richtsmeier JT. Tissue-specific responses to aberrant FGF signaling in complex head phenotypes. Dev Dyn 2013; 242:80-94. [PMID: 23172727 PMCID: PMC3556393 DOI: 10.1002/dvdy.23903] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 10/30/2012] [Accepted: 11/02/2012] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND The role of fibroblast growth factor and receptor (FGF/FGFR) signaling in bone development is well studied, partly because mutations in FGFRs cause human diseases of achondroplasia and FGFR-related craniosynostosis syndromes including Crouzon syndrome. The FGFR2c C342Y mutation is a frequent cause of Crouzon syndrome, characterized by premature cranial vault suture closure, midfacial deficiency, and neurocranial dysmorphology. Here, using newborn Fgfr2c(C342Y/+) Crouzon syndrome mice, we tested whether the phenotypic effects of this mutation go beyond the skeletal tissues of the skull, altering the development of other non-skeletal head tissues including the brain, the eyes, the nasopharynx, and the inner ears. RESULTS Quantitative analysis of 3D multimodal imaging (high-resolution micro-computed tomography and magnetic resonance microscopy) revealed local differences in skull morphology and coronal suture patency between Fgfr2c(C342Y/+) mice and unaffected littermates, as well as changes in brain shape but not brain size, significant reductions in nasopharyngeal and eye volumes, and no difference in inner ear volume in Fgfr2c(C342Y/+) mice. CONCLUSIONS These findings provide an expanded catalogue of clinical phenotypes in Crouzon syndrome caused by aberrant FGF/FGFR signaling and evidence of the broad role for FGF/FGFR signaling in development and evolution of the vertebrate head.
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Affiliation(s)
- Neus Martínez-Abadías
- Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania
| | - Susan M. Motch
- Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania
| | - Talia L. Pankratz
- Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania
| | - Yingli Wang
- Department of Genetics and Genomic Sciences, Mount Sinai SOM, New York, New York
| | - Kristina Aldridge
- Department of Pathology and Anatomical Sciences, University of Missouri SOM, Columbia, MO
| | - Ethylin Wang Jabs
- Department of Genetics and Genomic Sciences, Mount Sinai SOM, New York, New York
| | - Joan T. Richtsmeier
- Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania
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Functional role of adult hippocampal neurogenesis as a therapeutic strategy for mental disorders. Neural Plast 2012; 2012:854285. [PMID: 23346419 PMCID: PMC3549353 DOI: 10.1155/2012/854285] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2012] [Revised: 11/30/2012] [Accepted: 11/30/2012] [Indexed: 02/07/2023] Open
Abstract
Adult neurogenesis, the process of generating new neurons from neural stem cells, plays significant roles in synaptic plasticity, memory, and mood regulation. In the mammalian brain, it continues to occur well into adulthood in discrete regions, namely, the hippocampus and olfactory bulb. During the past decade, significant progress has been made in understanding the mechanisms regulating adult hippocampal neurogenesis and its role in the etiology of mental disorders. In addition, adult hippocampal neurogenesis is highly correlated with the remission of the antidepressant effect. In this paper, we discuss three major psychiatric disorders, depression, schizophrenia, and drug addiction, in light of preclinical evidence used in establishing the neurobiological significance of adult neurogenesis. We interpret the significance of these results and pose questions that remain unanswered. Potential treatments which include electroconvulsive therapy, deep brain stimulation, chemical antidepressants, and exercise therapy are discussed. While consensus lacks on specific mechanisms, we highlight evidence which indicates that these treatments may function via an increase in neural progenitor proliferation and changes to the hippocampal circuitry. Establishing a significant role of adult neurogenesis in the pathogenicity of psychiatric disorders may hold the key to potential strategies toward effective treatment.
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Abstract
INTRODUCTION Apert syndrome is one of the more clinically distinct craniosynostosis syndromes in man. It is caused by gain-of-function mutations in FGFR2, over 98% of which are the two amino acid substitution mutations S252W and P253R. FGFR2 is widely expressed throughout development, so that many tissues are adversely affected in Apert syndrome, particularly the calvarial bones, which begin to fuse during embryonic development, and the brain. DISCUSSION Mouse models of both of these two causative mutations and a third rare splice mutation have been created and display many of the phenotypes typical of Apert syndrome. The molecular and cellular mechanisms underlying Apert phenotypes have begun to be elucidated, and proof-of-principle treatment of these phenotypes by chemical inhibitor and gene-based therapies has been demonstrated.
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Huettl RE, Haehl T, Huber AB. Fasciculation and guidance of spinal motor axons in the absence of FGFR2 signaling. PLoS One 2012; 7:e41095. [PMID: 22815929 PMCID: PMC3398880 DOI: 10.1371/journal.pone.0041095] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 06/18/2012] [Indexed: 11/18/2022] Open
Abstract
During development, fibroblast growth factors (FGF) are essential for early patterning events along the anterior-posterior axis, conferring positional identity to spinal motor neurons by activation of different Hox codes. In the periphery, signaling through one of four fibroblast growth factor receptors supports the development of the skeleton, as well as induction and maintenance of extremities. In previous studies, FGF receptor 2 (FGFR2) was found to interact with axon bound molecules involved in axon fasciculation and extension, thus rendering this receptor an interesting candidate for the promotion of proper peripheral innervation. However, while the involvement of FGFR2 in limb bud induction has been extensively studied, its role during axon elongation and formation of distinct nervous projections has not been addressed so far. We show here that motor neurons in the spinal cord express FGFR2 and other family members during the establishment of motor connections to the forelimb and axial musculature. Employing a conditional genetic approach to selectively ablate FGFR2 from motor neurons we found that the patterning of motor columns and the expression patterns of other FGF receptors and Sema3A in the motor columns of mutant embryos are not altered. In the absence of FGFR2 signaling, pathfinding of motor axons is intact, and also fasciculation, distal advancement of motor nerves and gross morphology and positioning of axonal projections are not altered. Our findings therefore show that FGFR2 is not required cell-autonomously in motor neurons during the formation of initial motor projections towards limb and axial musculature.
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Affiliation(s)
- Rosa-Eva Huettl
- Institute of Developmental Genetics, Helmholtz Zentrum München – German Research Center for Environmental Health, Neuherberg, Germany
| | - Teresa Haehl
- Institute of Developmental Genetics, Helmholtz Zentrum München – German Research Center for Environmental Health, Neuherberg, Germany
| | - Andrea B. Huber
- Institute of Developmental Genetics, Helmholtz Zentrum München – German Research Center for Environmental Health, Neuherberg, Germany
- * E-mail:
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Hagemann AIH, Scholpp S. The Tale of the Three Brothers - Shh, Wnt, and Fgf during Development of the Thalamus. Front Neurosci 2012; 6:76. [PMID: 22654733 PMCID: PMC3361129 DOI: 10.3389/fnins.2012.00076] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 05/04/2012] [Indexed: 12/19/2022] Open
Abstract
The thalamic complex is an essential part of the brain that requires a combination of specialized activities to attain its final complexity. In the following review we will describe the induction process of the mid-diencephalic organizer (MDO) where three different signaling pathways merge: Wnt, Shh, and Fgf. Here, we dissect the function of each signaling pathway in the thalamus in chronological order of their appearance. First we describe the Wnt mediated induction of the MDO and compartition of the caudal forebrain, then the Shh mediated determination of proneural gene expression before discussing recent progress in characterizing Fgf function during thalamus development. Then, we focus on transcription factors, which are regulated by these pathways and which play a pivotal role in neurogenesis in the thalamus. The three signaling pathways act together in a strictly regulated chronology to orchestrate the development of the entire thalamus.
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Affiliation(s)
- Anja I H Hagemann
- Karlsruhe Institute of Technology, Institute of Toxicology and Genetics Karlsruhe, Germany
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Jacques BE, Dabdoub A, Kelley MW. Fgf signaling regulates development and transdifferentiation of hair cells and supporting cells in the basilar papilla. Hear Res 2012; 289:27-39. [PMID: 22575790 DOI: 10.1016/j.heares.2012.04.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 04/24/2012] [Accepted: 04/24/2012] [Indexed: 11/17/2022]
Abstract
The avian basilar papilla (BP) is a likely homolog of the auditory sensory epithelium of the mammalian cochlea, the organ of Corti. During mammalian development Fibroblast growth factor receptor-3 (Fgfr3) is known to regulate the differentiation of auditory mechanosensory hair cells (HCs) and supporting cells (SCs), both of which are required for sound detection. Fgfr3 is expressed in developing progenitor cells (PCs) and SCs of both the BP and the organ of Corti; however its role in BP development is unknown. Here we utilized an in vitro whole organ embryonic culture system to examine the role of Fgf signaling in the developing avian cochlea. SU5402 (an antagonist of Fgf signaling) was applied to developing BP cultures at different stages to assay the role of Fgf signaling during HC formation. Similar to the observed effects of inhibition of Fgfr3 in the mammalian cochlea, Fgfr inhibition in the developing BP increased the number of HCs that formed. This increase was not associated with increased proliferation, suggesting that inhibition of the Fgf pathway leads to the direct conversion of PCs or supporting cells into HCs, a process known as transdifferentiation. This also implies that Fgf signaling is required to prevent the conversion of PCs and SCs into HCs. The ability of Fgf signaling to inhibit transdifferentiation suggests that its down-regulation may be essential for the initial steps of HC formation, as well as for the maintenance of SC phenotypes.
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Affiliation(s)
- Bonnie E Jacques
- Laboratory of Cochlear Development, NIDCD, NIH, Porter Neuroscience Research Center, 35 Convent Dr, Room 2A-100, Bethesda, MD 20892-3729, USA.
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