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Hirota J. Molecular mechanisms of differentiation and class choice of olfactory sensory neurons. Genesis 2024; 62:e23587. [PMID: 38454646 DOI: 10.1002/dvg.23587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 01/10/2024] [Accepted: 01/29/2024] [Indexed: 03/09/2024]
Abstract
The sense of smell is intricately linked to essential animal behaviors necessary for individual survival and species preservation. During vertebrate evolution, odorant receptors (ORs), responsible for detecting odor molecules, have evolved to adapt to changing environments, transitioning from aquatic to terrestrial habitats and accommodating increasing complex chemical environments. These evolutionary pressures have given rise to the largest gene family in vertebrate genomes. Vertebrate ORs are phylogenetically divided into two major classes; class I and class II. Class I OR genes, initially identified in fish and frog, have persisted across vertebrate species. On the other hand, class II OR genes are unique to terrestrial animals, accounting for ~90% of mammalian OR genes. In mice, each olfactory sensory neuron (OSN) expresses a single functional allele of a single OR gene from either the class I or class II OR repertoire. This one neuron-one receptor rule is established through two sequential steps: specification of OR class and subsequent exclusive OR expression from the corresponding OR class. Consequently, OSNs acquire diverse neuronal identities during the process of OSN differentiation, enabling animals to detect a wide array of odor molecules. This review provides an overview of the OSN differentiation process through which OSN diversity is achieved, primarily using the mouse as a model animal.
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Affiliation(s)
- Junji Hirota
- Department of Life Science and Technology, Graduate School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
- Center for Integrative Biosciences, Tokyo Institute of Technology, Yokohama, Japan
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Chung WCJ, Tsai PS. The initiation and maintenance of gonadotropin-releasing hormone neuron identity in congenital hypogonadotropic hypogonadism. Front Endocrinol (Lausanne) 2023; 14:1166132. [PMID: 37181038 PMCID: PMC10173152 DOI: 10.3389/fendo.2023.1166132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 04/12/2023] [Indexed: 05/16/2023] Open
Abstract
Neurons that secrete gonadotropin-releasing hormone (GnRH) drive vertebrate reproduction. Genetic lesions that disrupt these neurons in humans lead to congenital hypogonadotropic hypogonadism (CHH) and reproductive failure. Studies on CHH have largely focused on the disruption of prenatal GnRH neuronal migration and postnatal GnRH secretory activity. However, recent evidence suggests a need to also focus on how GnRH neurons initiate and maintain their identity during prenatal and postnatal periods. This review will provide a brief overview of what is known about these processes and several gaps in our knowledge, with an emphasis on how disruption of GnRH neuronal identity can lead to CHH phenotypes.
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Affiliation(s)
- Wilson CJ Chung
- Department of Biological Sciences, Kent State University, Kent, OH, United States
| | - Pei-San Tsai
- Department of Integrative Physiology, University of Colorado, Boulder, CO, United States
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Im S, Moon C. Transcriptional regulatory network during development in the olfactory epithelium. BMB Rep 2016; 48:599-608. [PMID: 26303973 PMCID: PMC4911201 DOI: 10.5483/bmbrep.2015.48.11.177] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Indexed: 12/22/2022] Open
Abstract
Regeneration, a process of reconstitution of the entire tissue, occurs throughout life in the olfactory epithelium (OE). Regeneration of OE consists of several stages: proliferation of progenitors, cell fate determination between neuronal and non-neuronal lineages, their differentiation and maturation. How the differentiated cell types that comprise the OE are regenerated, is one of the central questions in olfactory developmental neurobiology. The past decade has witnessed considerable progress regarding the regulation of transcription factors (TFs) involved in the remarkable regenerative potential of OE. Here, we review current state of knowledge of the transcriptional regulatory networks that are powerful modulators of the acquisition and maintenance of developmental stages during regeneration in the OE. Advance in our understanding of regeneration will not only shed light on the basic principles of adult plasticity of cell identity, but may also lead to new approaches for using stem cells and reprogramming after injury or degenerative neurological diseases.
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Affiliation(s)
- SeungYeong Im
- Department of Brain & Cognitive Sciences, Graduate School, Daegu Gyeungbuk Institute of Science and Technology, Daegu 42988, Korea
| | - Cheil Moon
- Department of Brain & Cognitive Sciences, Graduate School, Daegu Gyeungbuk Institute of Science and Technology, Daegu 42988, Korea
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Chung WCJ, Linscott ML, Rodriguez KM, Stewart CE. The Regulation and Function of Fibroblast Growth Factor 8 and Its Function during Gonadotropin-Releasing Hormone Neuron Development. Front Endocrinol (Lausanne) 2016; 7:114. [PMID: 27656162 PMCID: PMC5011149 DOI: 10.3389/fendo.2016.00114] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 08/08/2016] [Indexed: 11/13/2022] Open
Abstract
Over the last few years, numerous studies solidified the hypothesis that fibroblast growth factor (FGF) signaling regulates neuroendocrine progenitor cell proliferation, fate specification, and cell survival and, therefore, is critical for the regulation and maintenance of homeostasis of the body. One important example that underscores the involvement of FGF signaling during neuroendocrine cell development is gonadotropin-releasing hormone (GnRH) neuron ontogenesis. Indeed, transgenic mice with reduced olfactory placode (OP) Fgf8 expression do not have GnRH neurons. This observation indicates the requirement of FGF8 signaling for the emergence of the GnRH neuronal system in the embryonic OP, the putative birth place of GnRH neurons. Mammalian reproductive success depends on the presence of GnRH neurons to stimulate gonadotropin secretion from the anterior pituitary, which activates gonadal steroidogenesis and gametogenesis. Together, these observations are critical for understanding the function of GnRH neurons and their control of the hypothalamus-pituitary-gonadal (HPG) axis to maintain fertility. Taken together, these studies illustrate that GnRH neuron emergence and hence HPG function is vulnerable to genomic and molecular signals that abnormally modify Fgf8 expression in the developing mouse OP. In this short review, we focus on research that is aimed at unraveling how androgen, all-trans retinoic acid, and how epigenetic factors modify control mouse OP Fgf8 transcription in the context of GnRH neuronal development and mammalian reproductive success.
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Affiliation(s)
- Wilson C. J. Chung
- Department of Biological Sciences, School of Biomedical Sciences, Kent State University, Kent, OH, USA
- *Correspondence: Wilson C. J. Chung,
| | - Megan L. Linscott
- Department of Biological Sciences, School of Biomedical Sciences, Kent State University, Kent, OH, USA
| | - Karla M. Rodriguez
- Department of Biological Sciences, School of Biomedical Sciences, Kent State University, Kent, OH, USA
| | - Courtney E. Stewart
- Department of Biological Sciences, School of Biomedical Sciences, Kent State University, Kent, OH, USA
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Stevenson EL, Corella KM, Chung WCJ. Ontogenesis of gonadotropin-releasing hormone neurons: a model for hypothalamic neuroendocrine cell development. Front Endocrinol (Lausanne) 2013; 4:89. [PMID: 23882261 PMCID: PMC3712253 DOI: 10.3389/fendo.2013.00089] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 07/02/2013] [Indexed: 02/02/2023] Open
Abstract
The vertebrate hypothalamo-pituitary-gonadal axis is the anatomical framework responsible for reproductive competence and species propagation. Essential to the coordinated actions of this three-tiered biological system is the fact that the regulatory inputs ultimately converge on the gonadotropin-releasing hormone (GnRH) neuronal system, which in rodents primarily resides in the preoptic/hypothalamic region. In this short review we will focus on: (1) the general embryonic temporal and spatial development of the rodent GnRH neuronal system, (2) the origin(s) of GnRH neurons, and (3) which transcription - and growth factors have been found to be critical for GnRH neuronal ontogenesis and cellular fate-specification. Moreover, we ask the question whether the molecular and cellular mechanisms involved in GnRH neuronal development may also play a role in the development of other hypophyseal secreting neuroendocrine cells in the hypothalamus.
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Affiliation(s)
- Erica L. Stevenson
- Department of Biological Sciences, School of Biomedical Sciences, Kent State University, Kent, OH, USA
| | - Kristina M. Corella
- Department of Biological Sciences, School of Biomedical Sciences, Kent State University, Kent, OH, USA
| | - Wilson C. J. Chung
- Department of Biological Sciences, School of Biomedical Sciences, Kent State University, Kent, OH, USA
- *Correspondence: Wilson C. J. Chung, Department of Biological Sciences, School of Biomedical Sciences, Kent State University, 222 Cunningham Hall, Kent, OH 44242, USA e-mail:
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Blomster LV, Vukovic J, Hendrickx DAE, Jung S, Harvey AR, Filgueira L, Ruitenberg MJ. CX₃CR1 deficiency exacerbates neuronal loss and impairs early regenerative responses in the target-ablated olfactory epithelium. Mol Cell Neurosci 2011; 48:236-45. [PMID: 21871566 DOI: 10.1016/j.mcn.2011.08.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Revised: 08/04/2011] [Accepted: 08/04/2011] [Indexed: 02/02/2023] Open
Abstract
The olfactory epithelium is a site of sustained adult neurogenesis where olfactory sensory neurons are continuously replaced from endogenous stem/progenitor cells. Epithelial macrophages have been implicated in the phagocytosis of degenerating cells but the molecular mechanisms allowing for their recruitment and activation while maintaining a neurogenic microenvironment are poorly understood. We have previously shown that the chemokine fractalkine (CX₃CL1) is expressed by olfactory sensory neurons and ensheathing cells in the olfactory epithelium. In turn, the fractalkine receptor, CX₃CR1, is expressed on macrophages and dendritic cells within the olfactory epithelium. We report that a selective cell death of olfactory sensory neurons in the epithelium of CX₃CR1-deficient mice via target ablation (i.e. olfactory bulbectomy) results in an exacerbated loss of olfactory sensory neurons compared to wild-type mice. In addition, reduced proliferation of intraepithelial stem/progenitor cells was observed in lesioned CX₃CR1-deficient mice, suggesting an impaired regenerative response. Importantly, a lack of CX₃CL1-signaling caused increased recruitment of macrophages into the olfactory epithelium, which in turn contained higher levels of pro-inflammatory cytokines (e.g. TNF-α and IL-6) as determined by qPCR. We also present novel data showing that, relative to wild-type, CX₃CR1-deficient macrophages have diminished phagocytic activity following stimulation with CX₃CL1. Collectively, our data indicate that signaling through the CX₃CR1 receptor modulates macrophage activity, resulting in an environment conducive to olfactory sensory neuron clearance and targeted replacement from endogenous stem/progenitor cells.
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Affiliation(s)
- Linda V Blomster
- School of Anatomy and Human Biology, The University of Western Australia, Perth, Australia
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Fujimura F, Horikawa Y, Morita T, Sugiyama J, Kimura S. Double Assembly Composed of Lectin Association with Columnar Molecular Assembly of Cyclic Tri-β-peptide Having Sugar Units. Biomacromolecules 2006; 8:611-6. [PMID: 17291084 DOI: 10.1021/bm060862d] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A novel double assembly was prepared by association between a columnar molecular assembly of cyclic tri-beta-peptides having sugar units and lectins. The NMR, FT-IR, and circular dichroism (CD) spectroscopy as well as computational calculations revealed that this compound took a flat and C3 symmetrical conformation and that the amide N-H and C=O groups protruded vertically to the ring plane. This disk-shaped molecule stacked one by one to form a columnar structure via intermolecular hydrogen bonds between the amide groups. WGA lectin moderately bound to this columnar assembly to form a double assembly. Another lectin (Con A) disturbed the columnar structure upon strong binding, and RCA lectin showed no binding. Fluorescence spectroscopy revealed that the association between WGA lectin and columnar assembly of cyclic glycopeptide could be achieved due to the high density of the hydroxyl groups on the assembly surface (cluster effects). Interestingly, after cross-linking the lectins bound to the columnar assembly (the double assembly) by glutaraldehyde, the core column of cyclic tri-beta-peptides could be washed away to leave the protein nanotube.
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Affiliation(s)
- Futoshi Fujimura
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
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Farbman AI. Personal reflections on 40 years of research in the chemical senses. ACTA ACUST UNITED AC 2005; 33:579-89. [PMID: 16217615 DOI: 10.1007/s11068-005-3327-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2005] [Accepted: 05/13/2005] [Indexed: 11/30/2022]
Affiliation(s)
- Albert I Farbman
- Department of Neurobiology & Physiology, Northwestern University, Evanston, IL 60208-3520, USA.
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Salazar I, Sánchez Quinteiro P. Differential development of binding sites for four lectins in the vomeronasal system of juvenile mouse: from the sensory transduction site to the first relay stage. Brain Res 2003; 979:15-26. [PMID: 12850566 DOI: 10.1016/s0006-8993(03)02835-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Four lectins -the galactose-specific BSI-B(4) (from Bandeiraea simplicifolia), the N-acetyl-galactosamine-specific DBA (from Dolichos biflorus), the L-fucose-specific UEA-I (from Ulex europaeus) and the (oligomeric N-acetylglucosamine)-specific LEA (from Lycopersicum esculentum)- were used to study the vomeronasal organ, vomeronasal nerves and accessory olfactory bulb of the mouse on embryonic days 11, 13, 15, 17 and 19, during the first 3 weeks after birth, at age 25 days, and after reaching maturity. No lectins labelled any structure before the 17th day of gestation, and even on the 19th day staining was sporadic and/or diffuse. During the early postnatal period, the lectin binding patterns differed from those of adults, but the division of the accessory olfactory bulb into anterior, rostral posterior and caudal posterior regions was already present and was shown up by the four lectins in a way that was coherent with the known zone-to-zone correspondence between the apical and basal zones of the sensory epithelium and the anterior and posterior accessory olfactory bulb, respectively. By age 25 days, the staining patterns were essentially those of the adult mouse. BSI-B(4) appears to be specific for the accessory vs. the main olfactory bulb throughout life.
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Affiliation(s)
- Ignacio Salazar
- Department of Anatomy and Embryology, Faculty of Veterinary, University of Santiago de Compostela, 27002, Lugo, Spain.
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Apfelbach R, Weiler E, Asselbergs WF, Polak EH, Slotnick B. Selective and reversible reduction of odor sensitivity in the rat by concanavalin A. Physiol Behav 1998; 65:513-6. [PMID: 9877418 DOI: 10.1016/s0031-9384(98)00197-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Rats were trained using an olfactometer to detect low concentrations of ethyl acetate (EA) or dimethyl disulphide vapor (DMDS). Concanavalin A (ConA) applied to the olfactory mucosa had no effect on ability of rats to detect low concentrations of EA but produced a marked deficit in detection in DMDS. DMDS detection performance returned to control levels 3 days after the ConA treatment. These results provide the first behavioral evidence for odor-specific inhibition by chemical modification of the olfactory epithelium and support the notion that ConA selectively inactivates one or more types (subclasses) of olfactory receptor proteins.
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Affiliation(s)
- R Apfelbach
- University of Tubingen, Department of Zoology, Germany
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Abstract
BACKGROUND The olfactory epithelial sustentacular cells may support the survival and function of olfactory receptor neurons, but few reagents are available to mark and manipulate such cells. METHODS Novel nasal cell-specific monoclonal antibodies were generated using whole cultured rat olfactory mucosal cells as the antigenic stimuli. They were characterized by immunostaining at the light level in rat tissues and newborn rat olfactory cell cultures, and at the electron microscopic level in adult tissues using freeze-substitution, post-embedding staining. RESULTS An IgMkappa monoclonal antibody designated 1F4 selectively labeled apical surfaces of the rat olfactory and respiratory epithelia in tissue sections and what appeared to be sustentacular cells in olfactory cell cultures. Using electron microscopy, 1F4 bound selectively to the microvilli of sustentacular cells and ductal cells of Bowman's glands in the olfactory epithelium, and to the microvilli and cilia of ciliated but not secretory cells in the respiratory epithelium. No staining was detected in olfactory receptor neurons, basal cells, or two types of microvilli-bearing cells that differed from sustentacular cells. A contrasting antibody, 2H4, bound to granules of secretory respiratory cells. Developmental expression of 1F4 binding began at E17 and increased at and after E18/E19. Bulbectomy did not alter 1F4 immunoreactivity. Cell culture studies found that the 1F4 epitope was external and insensitive to trypsin treatment, and that both 1F4 and 2H4 positive cells required contact with aggregated cells for survival up to fifteen days in vitro. CONCLUSIONS The antibody 1F4 is a useful marker and potential manipulation reagent specific for sustentacular cells and their microvilli.
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Affiliation(s)
- S K Pixley
- Department of Cell Biology, Neurobiology, and Anatomy, University of Cincinnati College of Medicine, Ohio 45267-0521, USA.
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In vitro generation of adult rat olfactory sensory neurons and regulation of maturation by coculture with CNS tissues. J Neurosci 1997. [PMID: 9096146 DOI: 10.1523/jneurosci.17-09-03120.1997] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Olfactory sensory neurons (OSNs) are continually generated throughout life. Although previous studies have examined neurogenesis in olfactory cell cultures derived from embryonic or newborn rodents, we demonstrate neurogenesis in cell cultures derived from adult rat tissues. Dissociated cells taken from adult rat nasal mucosal tissues (ANM cells) were plated onto a feeder layer of newborn rat cortical glia (astrocytes) in serum-free conditions. Immature OSNs (stained for neuron-specific tubulin, NST) increased in number between 1 and 5 d in vitro (DIV) and in mass thereafter. Mature OSN (stained for olfactory marker protein, OMP) numbers decreased between 1 and 5 DIV, then increased over 5 DIV values by 12 and 15 DIV. Pulse labeling with [3H]thymidine confirmed in vitro neurogenesis. To determine whether the target cells for OSNs, olfactory bulb (OB) neurons, provide trophic support, dissociated newborn rat OB cells were cocultured with ANM cells on glia. This resulted in greater numbers of OMP-positive (OMP+) neurons after 9 DIV than ANM-alone cultures. This neurotrophic effect was not OB specific. Addition of newborn rat cerebellar and embryonic rat ventral mesencephalic cells to ANM cells also increased OMP+ neurons, whereas addition of newborn rat cortical cells or controls (purified glia or fibroblasts) did not. Changes in numbers of dopaminergic neurons (stained for tyrosine hydroxylase), present in OB and VM cultures, did not correlate with OMP+ neuronal increases. Thus, cultures of adult rat OSNs demonstrate neurogenesis, and trophic/maturation support is variably provided by CNS neurons (and not glia).
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