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Brown TL, Horton EC, Craig EW, Goo CEA, Black EC, Hewitt MN, Yee NG, Fan ET, Raible DW, Rasmussen JP. Dermal appendage-dependent patterning of zebrafish atoh1a+ Merkel cells. eLife 2023; 12:85800. [PMID: 36648063 PMCID: PMC9901935 DOI: 10.7554/elife.85800] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 01/11/2023] [Indexed: 01/18/2023] Open
Abstract
Touch system function requires precise interactions between specialized skin cells and somatosensory axons, as exemplified by the vertebrate mechanosensory Merkel cell-neurite complex. Development and patterning of Merkel cells and associated neurites during skin organogenesis remain poorly understood, partly due to the in utero development of mammalian embryos. Here, we discover Merkel cells in the zebrafish epidermis and identify Atonal homolog 1a (Atoh1a) as a marker of zebrafish Merkel cells. We show that zebrafish Merkel cells derive from basal keratinocytes, express neurosecretory and mechanosensory machinery, extend actin-rich microvilli, and complex with somatosensory axons, all hallmarks of mammalian Merkel cells. Merkel cells populate all major adult skin compartments, with region-specific densities and distribution patterns. In vivo photoconversion reveals that Merkel cells undergo steady loss and replenishment during skin homeostasis. Merkel cells develop concomitant with dermal appendages along the trunk and loss of Ectodysplasin signaling, which prevents dermal appendage formation, reduces Merkel cell density by affecting cell differentiation. By contrast, altering dermal appendage morphology changes the distribution, but not density, of Merkel cells. Overall, our studies provide insights into touch system maturation during skin organogenesis and establish zebrafish as an experimentally accessible in vivo model for the study of Merkel cell biology.
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Affiliation(s)
- Tanya L Brown
- Department of Biology, University of WashingtonSeattleUnited States
| | - Emma C Horton
- Department of Biology, University of WashingtonSeattleUnited States
| | - Evan W Craig
- Department of Biology, University of WashingtonSeattleUnited States
| | - Camille EA Goo
- Department of Biology, University of WashingtonSeattleUnited States
| | - Erik C Black
- Department of Biology, University of WashingtonSeattleUnited States
- Molecular and Cellular Biology Program, University of WashingtonSeattleUnited States
| | - Madeleine N Hewitt
- Molecular and Cellular Biology Program, University of WashingtonSeattleUnited States
- Department of Biological Structure, University of WashingtonSeattleUnited States
| | - Nathaniel G Yee
- Department of Biology, University of WashingtonSeattleUnited States
| | - Everett T Fan
- Department of Biology, University of WashingtonSeattleUnited States
| | - David W Raible
- Department of Biological Structure, University of WashingtonSeattleUnited States
- Department of Otolaryngology - Head and Neck Surgery, University of WashingtonSeattleUnited States
- Institute for Stem Cell and Regenerative Medicine, University of WashingtonSeattleUnited States
| | - Jeffrey P Rasmussen
- Department of Biology, University of WashingtonSeattleUnited States
- Institute for Stem Cell and Regenerative Medicine, University of WashingtonSeattleUnited States
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2
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Bataille A, Le Gall C, Misery L, Talagas M. Merkel Cells Are Multimodal Sensory Cells: A Review of Study Methods. Cells 2022; 11:cells11233827. [PMID: 36497085 PMCID: PMC9737130 DOI: 10.3390/cells11233827] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 11/23/2022] [Accepted: 11/24/2022] [Indexed: 12/05/2022] Open
Abstract
Merkel cells (MCs) are rare multimodal epidermal sensory cells. Due to their interactions with slowly adapting type 1 (SA1) Aβ low-threshold mechanoreceptor (Aβ-LTMRs) afferents neurons to form Merkel complexes, they are considered to be part of the main tactile terminal organ involved in the light touch sensation. This function has been explored over time by ex vivo, in vivo, in vitro, and in silico approaches. Ex vivo studies have made it possible to characterize the topography, morphology, and cellular environment of these cells. The interactions of MCs with surrounding cells continue to be studied by ex vivo but also in vitro approaches. Indeed, in vitro models have improved the understanding of communication of MCs with other cells present in the skin at the cellular and molecular levels. As for in vivo methods, the sensory role of MC complexes can be demonstrated by observing physiological or pathological behavior after genetic modification in mouse models. In silico models are emerging and aim to elucidate the sensory coding mechanisms of these complexes. The different methods to study MC complexes presented in this review may allow the investigation of their involvement in other physiological and pathophysiological mechanisms, despite the difficulties in exploring these cells, in particular due to their rarity.
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Affiliation(s)
- Adeline Bataille
- LIEN—Laboratoire Interactions Epithélium Neurones, Brest University, F-29200 Brest, France
- Correspondence:
| | - Christelle Le Gall
- LIEN—Laboratoire Interactions Epithélium Neurones, Brest University, F-29200 Brest, France
- Department of Dermatology, Brest University Hospital, F-29200 Brest, France
| | - Laurent Misery
- LIEN—Laboratoire Interactions Epithélium Neurones, Brest University, F-29200 Brest, France
- Department of Dermatology, Brest University Hospital, F-29200 Brest, France
| | - Matthieu Talagas
- LIEN—Laboratoire Interactions Epithélium Neurones, Brest University, F-29200 Brest, France
- Department of Dermatology, Brest University Hospital, F-29200 Brest, France
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3
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Kervarrec T, Samimi M, Guyétant S, Sarma B, Chéret J, Blanchard E, Berthon P, Schrama D, Houben R, Touzé A. Histogenesis of Merkel Cell Carcinoma: A Comprehensive Review. Front Oncol 2019; 9:451. [PMID: 31245285 PMCID: PMC6579919 DOI: 10.3389/fonc.2019.00451] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 05/13/2019] [Indexed: 12/11/2022] Open
Abstract
Merkel cell carcinoma (MCC) is a primary neuroendocrine carcinoma of the skin. This neoplasia features aggressive behavior, resulting in a 5-year overall survival rate of 40%. In 2008, Feng et al. identified Merkel cell polyomavirus (MCPyV) integration into the host genome as the main event leading to MCC oncogenesis. However, despite identification of this crucial viral oncogenic trigger, the nature of the cell in which MCC oncogenesis occurs is actually unknown. In fact, several hypotheses have been proposed. Despite the large similarity in phenotype features between MCC tumor cells and physiological Merkel cells (MCs), a specialized subpopulation of the epidermis acting as mechanoreceptor of the skin, several points argue against the hypothesis that MCC derives directly from MCs. Alternatively, MCPyV integration could occur in another cell type and induce acquisition of an MC-like phenotype. Accordingly, an epithelial as well as a fibroblastic or B-cell origin of MCC has been proposed mainly based on phenotype similarities shared by MCC and these potential ancestries. The aim of this present review is to provide a comprehensive review of the current knowledge of the histogenesis of MCC.
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Affiliation(s)
- Thibault Kervarrec
- Department of Pathology, Centre Hospitalier Universitaire de Tours, Tours, France.,ISP "Biologie des infections à polyomavirus" team, UMR INRA 1282, University of Tours, Tours, France.,Department of Dermatology, Venereology and Allergology, University Hospital Würzburg, Würzburg, Germany
| | - Mahtab Samimi
- ISP "Biologie des infections à polyomavirus" team, UMR INRA 1282, University of Tours, Tours, France.,Departement of Dermatology, Centre Hospitalier Universitaire de Tours, Tours, France
| | - Serge Guyétant
- Department of Pathology, Centre Hospitalier Universitaire de Tours, Tours, France.,ISP "Biologie des infections à polyomavirus" team, UMR INRA 1282, University of Tours, Tours, France
| | - Bhavishya Sarma
- Department of Dermatology, Venereology and Allergology, University Hospital Würzburg, Würzburg, Germany
| | - Jérémy Chéret
- Monasterium Laboratory, Skin and Hair Research Solutions GmbH, Münster, Germany
| | - Emmanuelle Blanchard
- Department of Pathology, Centre Hospitalier Universitaire de Tours, Tours, France.,Plateforme IBiSA de Microscopie Electronique, INSERM 1259, Université de Tours, Tours, France
| | - Patricia Berthon
- ISP "Biologie des infections à polyomavirus" team, UMR INRA 1282, University of Tours, Tours, France
| | - David Schrama
- Department of Dermatology, Venereology and Allergology, University Hospital Würzburg, Würzburg, Germany
| | - Roland Houben
- Department of Dermatology, Venereology and Allergology, University Hospital Würzburg, Würzburg, Germany
| | - Antoine Touzé
- ISP "Biologie des infections à polyomavirus" team, UMR INRA 1282, University of Tours, Tours, France
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4
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Ramírez GA, de Los Monteros AE. Study on the Role of Histochemical Stains in Identifying Merkel Cells in Dogs. Anat Rec (Hoboken) 2018; 302:1458-1464. [PMID: 30378297 DOI: 10.1002/ar.24013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 08/12/2018] [Accepted: 09/05/2018] [Indexed: 11/11/2022]
Abstract
Merkel cells (MCs) are neuroendocrine cells involved with tactile sense, growth, differentiation, and homeostasis of the skin as well as in different cutaneous diseases. Specific staining techniques are required for their identification because they are not easily visible in paraffin sections stained with hematoxylin and eosin. The present study assess the histochemical features of the MCs in dogs comparing with those described for other mammals in the literature and with the use of immunohistochemistry. A systematic study of samples from MCs-rich areas from healthy dogs was carried out by use of several histologic stains, including metachromatic staining, silver stains, methylene blue, periodic acid-Schiff stain, and osmium-based staining method. MCs were detected by the Grimelius argyrophilic stain in 86.7% of the specimens. The staining was showed as dark-brown granular cytoplasmic and consistently polarized to the basal cell cytoplasm matching with the cellular distribution of the characteristic neurosecretory granules. Some modifications in the standard staining protocol, including rinsing, silver reimpregnation, and counterstain dye, enhanced the MCs identification in stratified squamous epithelium. When compared with Cytokeratin 20-immunolabeled serial sections several MCs appeared nonstained with the argyrophilic method. These differences in MC numbers between stains were statistically significant. Other histologic stains failed to identify MCs in the specimens. The results of this study indicate that Grimelius argyrophilic stain is a suitable method for demonstration of MCs in the stratified squamous epithelium of skin and mucosa. Discussion on its utility when compared with immunohistochemistry and a review of the scientific literature is also presented. Anat Rec, 302:1458-1464, 2019. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Gustavo A Ramírez
- Department of Animal Science, School of Agriculture, Food Science and Veterinary Medicine (ETSEA), University of Lleida, Lleida, Spain.,Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas de Gran Canaria, Campus Universitario Cardones, Las Palmas, Spain
| | - Antonio Espinosa de Los Monteros
- Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas de Gran Canaria, Campus Universitario Cardones, Las Palmas, Spain
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5
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Ramírez GA, Rodríguez F, Suárez-Bonnet A, Herráez P, Castro-Alonso A, Rivero M, Espinosa de los Monteros A. Study of Merkel cells in the dog through the immunohistochemical expression of five different commercial antibodies: comparative analysis. JOURNAL OF APPLIED ANIMAL RESEARCH 2018. [DOI: 10.1080/09712119.2017.1322089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Gustavo A. Ramírez
- Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas de Gran Canaria, Arucas, Las Palmas, Spain
- Department of Animal Science, Veterinary College, ETSEA, University of Lleida, Lleida, Spain
| | - Francisco Rodríguez
- Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas de Gran Canaria, Arucas, Las Palmas, Spain
| | - Alejandro Suárez-Bonnet
- Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas de Gran Canaria, Arucas, Las Palmas, Spain
| | - Pedro Herráez
- Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas de Gran Canaria, Arucas, Las Palmas, Spain
| | - Ayoze Castro-Alonso
- Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas de Gran Canaria, Arucas, Las Palmas, Spain
| | - Miguel Rivero
- Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas de Gran Canaria, Arucas, Las Palmas, Spain
| | - Antonio Espinosa de los Monteros
- Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas de Gran Canaria, Arucas, Las Palmas, Spain
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6
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Bouvier V, Roudaut Y, Osorio N, Aimonetti JM, Ribot-Ciscar E, Penalba V, Merrot T, Lebonvallet N, Le Gall-Ianotto C, Misery L, Delmas P, Crest M. Merkel Cells Sense Cooling with TRPM8 Channels. J Invest Dermatol 2017; 138:946-956. [PMID: 29138055 DOI: 10.1016/j.jid.2017.11.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 10/02/2017] [Accepted: 11/03/2017] [Indexed: 10/18/2022]
Abstract
In the skin, Merkel cells connect with keratinocytes and Aβ nerve fibers to form a touch receptor that functions as a slow adapting mechanoreceptor (slow adapting type 1). In human and mouse Merkel cells, we observed an increased concentration of intracellular Ca2+ ions in response to cold temperature and transient receptor potential melastatine 8 (TRPM8) ion channel agonists. A reduction in the response to cooling and TRPM8 agonists occurred after the addition of TRPM8 antagonists, as well as in TRPM8 knockout mice. Cold temperature and TRPM8 agonists also induced a current that was inhibited by a TRPM8 antagonist. Our results indicate that Merkel cells sense cooling through TRPM8 channels. We hypothesized that cooling modulates the slow adapting type 1 receptor response. Cooling mouse skin to 22°C reduced the slow adapting type 1 receptor discharge frequency. Interestingly, we observed no such reduction in TRPM8 knockout mice. Similarly, in human skin, a temperature of 22°C applied to the slow adapting type 1 receptive field reduced the spiking discharge. Altogether, our results indicate that Merkel cells are polymodal sensory cells that respond to mild cold stimuli through the activation of TRPM8 channels. Thermal activation of Merkel cells, and possibly other TRPM8-expressing non-neuronal cells, such as keratinocytes, potentially adapts the discharge of slow adapting type 1 receptors during cooling.
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Affiliation(s)
- Valentine Bouvier
- Aix Marseille Université, Centre National de la Recherche Scientifique, Centre de Recherche en Neurobiologie-Neurophysiologie de Marseille, UMR 7286, Marseille, France
| | - Yann Roudaut
- Aix Marseille Université, Centre National de la Recherche Scientifique, Centre de Recherche en Neurobiologie-Neurophysiologie de Marseille, UMR 7286, Marseille, France
| | - Nancy Osorio
- Aix Marseille Université, Centre National de la Recherche Scientifique, Centre de Recherche en Neurobiologie-Neurophysiologie de Marseille, UMR 7286, Marseille, France
| | - Jean-Marc Aimonetti
- Aix-Marseille Université, Centre National de la Recherche Scientifique, Laboratoire de Neurosciences Intégratives et Adaptatives, UMR 7260, Marseille, France
| | - Edith Ribot-Ciscar
- Aix-Marseille Université, Centre National de la Recherche Scientifique, Laboratoire de Neurosciences Intégratives et Adaptatives, UMR 7260, Marseille, France
| | - Virginie Penalba
- Aix Marseille Université, Centre National de la Recherche Scientifique, Centre de Recherche en Neurobiologie-Neurophysiologie de Marseille, UMR 7286, Marseille, France
| | - Thierry Merrot
- Aix Marseille Université, Assistance Publique-Hôpitaux de Marseille, Hôpital Nord, Service de Chirurgie Infantile, Marseille, France
| | | | | | - Laurent Misery
- Université de Brest, Laboratoire de Neurosciences, Brest, France
| | - Patrick Delmas
- Aix Marseille Université, Centre National de la Recherche Scientifique, Centre de Recherche en Neurobiologie-Neurophysiologie de Marseille, UMR 7286, Marseille, France
| | - Marcel Crest
- Aix Marseille Université, Centre National de la Recherche Scientifique, Centre de Recherche en Neurobiologie-Neurophysiologie de Marseille, UMR 7286, Marseille, France.
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7
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Bertolini M, Pretzlaff M, Sulk M, Bähr M, Gherardini J, Uchida Y, Reibelt M, Kinori M, Rossi A, Bíró T, Paus R. Vasoactive intestinal peptide, whose receptor-mediated signalling may be defective in alopecia areata, provides protection from hair follicle immune privilege collapse. Br J Dermatol 2016; 175:531-41. [PMID: 27059672 DOI: 10.1111/bjd.14645] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/21/2016] [Indexed: 12/20/2022]
Abstract
BACKGROUND Alopecia areata (AA) is an autoimmune disorder whose pathogenesis involves the collapse of the relative immune privilege (IP) of the hair follicle (HF). Given that vasoactive intestinal peptide (VIP) is an immunoinhibitory neuropeptide released by perifollicular sensory nerve fibres, which play a role in IP maintenance, it may modulate human HF-IP and thus be therapeutically relevant for AA. OBJECTIVES To answer the following questions: Do human HFs express VIP receptors, and does their stimulation protect from or restore experimentally induced HF-IP collapse? Is VIP signalling defective in AA HFs? METHODS Firstly, VIP and VIP receptor (VPAC1, VPAC2) expression in human scalp HFs and AA skin was assessed. In HF organ culture, we then explored whether VIP treatment can restore and/or protect from interferon-γ-induced HF-IP collapse, assessing the expression of the key IP markers by quantitative (immuno-)histomorphometry. RESULTS Here we provide the first evidence that VIP receptors are expressed in the epithelium of healthy human HFs at the gene and protein level. Furthermore, VIP receptor protein expression, but not VIP(+) nerve fibres, is significantly downregulated in lesional hair bulbs of patients with AA, suggesting defects in VIP receptor-mediated signalling. Moreover, we show that VIP protects the HF from experimentally induced IP collapse in vitro, but does not fully restore it once collapsed. CONCLUSIONS These pilot data suggest that insufficient VIP receptor-mediated signalling may contribute to impairing HF-IP in patients with AA, and that VIP is a promising candidate 'HF-IP guardian' that may be therapeutically exploited to inhibit the progression of AA lesions.
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Affiliation(s)
- M Bertolini
- Department of Dermatology, University of Münster, Münster, Germany.
| | - M Pretzlaff
- Department of Dermatology, University of Lübeck, Lübeck, Germany
| | - M Sulk
- Department of Dermatology, University of Münster, Münster, Germany
| | - M Bähr
- Department of Dermatology, University of Lübeck, Lübeck, Germany
| | - J Gherardini
- Department of Dermatology, University of Münster, Münster, Germany
| | - Y Uchida
- Department of Dermatology, University of Münster, Münster, Germany.,Department of Dermatology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - M Reibelt
- Department of Dermatology, University of Lübeck, Lübeck, Germany
| | - M Kinori
- Department of Ophthalmology, Sheba Medical Center, Tel Hashomer, Israel
| | - A Rossi
- Department of Internal Medicine and Medical Specialties, University 'La Sapienza', Rome, Italy
| | - T Bíró
- DE-MTA 'Lendület' Cellular Physiology Research Group, Departments of Immunology and Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - R Paus
- Department of Dermatology, University of Münster, Münster, Germany.,Centre for Dermatology Research, Institute of Inflammation and Repair, University of Manchester, Manchester, U.K
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8
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Ramírez GA, Rodríguez F, Quesada Ó, Herráez P, Fernández A, Espinosa-de-los-Monteros A. Anatomical Mapping and Density of Merkel Cells in Skin and Mucosae of the Dog. Anat Rec (Hoboken) 2016; 299:1157-64. [DOI: 10.1002/ar.23387] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 03/22/2016] [Accepted: 04/23/2016] [Indexed: 12/11/2022]
Affiliation(s)
- Gustavo A. Ramírez
- Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas De Gran Canaria, Campus Universitario Cardones; Arucas Las Palmas 45413 Spain
| | - Francisco Rodríguez
- Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas De Gran Canaria, Campus Universitario Cardones; Arucas Las Palmas 45413 Spain
| | - Óscar Quesada
- Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas De Gran Canaria, Campus Universitario Cardones; Arucas Las Palmas 45413 Spain
| | - Pedro Herráez
- Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas De Gran Canaria, Campus Universitario Cardones; Arucas Las Palmas 45413 Spain
| | - Antonio Fernández
- Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas De Gran Canaria, Campus Universitario Cardones; Arucas Las Palmas 45413 Spain
| | - Antonio Espinosa-de-los-Monteros
- Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas De Gran Canaria, Campus Universitario Cardones; Arucas Las Palmas 45413 Spain
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9
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Ko MH, Yang ML, Youn SC, Lan CT, Tseng TJ. Intact subepidermal nerve fibers mediate mechanical hypersensitivity via the activation of protein kinase C gamma in spared nerve injury. Mol Pain 2016; 12:12/0/1744806916656189. [PMID: 27296621 PMCID: PMC4956387 DOI: 10.1177/1744806916656189] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Spared nerve injury is an important neuropathic pain model for investigating the role of intact primary afferents in the skin on pain hypersensitivity. However, potential cellular mechanisms remain poorly understood. In phosphoinositide-3 kinase pathway, pyruvate dehydrogenase kinase 1 (PDK1) participates in the regulation of neuronal plasticity for central sensitization. The downstream cascades of PDK1 include: (1) protein kinase C gamma (PKCg) controls the trafficking and phosphorylation of ionotropic glutamate receptor; (2) protein kinase B (Akt)/the mammalian target of rapamycin (mTOR) signaling is responsible for local protein synthesis. Under these statements, we therefore hypothesized that an increase of PKCg activation and mTOR-dependent PKCg synthesis in intact primary afferents after SNI might contribute to pain hypersensitivity. RESULTS The variants of spared nerve injury were performed in Sprague-Dawley rats by transecting any two of the three branches of the sciatic nerve, leaving only one branch intact. Following SNIt (spared tibial branch), mechanical hyperalgesia and mechanical allodynia, but not thermal hyperalgesia, were significantly induced. In the first footpad, normal epidermal innervations were verified by the protein gene product 9.5 (PGP9.5)- and growth-associated protein 43 (GAP43)-immunoreactive (IR) intraepidermal nerve fibers (IENFs) densities. Furthermore, the rapid increases of phospho-PKCg- and phosphomTOR-IR subepidermal nerve fibers (SENFs) areas were distinct gathered from the results of PGP9.5-, GAP43-, and neurofilament 200 (NF200)-IR SENFs areas. The efficacy of PKC inhibitor (GF 109203X) or mTOR complex 1 inhibitor (rapamycin) for attenuating mechanical hyperalgesia and mechanical allodynia by intraplantar injection was dose-dependent. CONCLUSIONS From results obtained in this study, we strongly recommend that the intact SENFs persistently increase PKCg activation and mTOR-dependent PKCg synthesis participate in the initiation and maintenance of mechanical hypersensitivity in spared nerve injury, which represents as a novel insight into the therapeutic strategy of pain in the periphery.
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Affiliation(s)
- Miau-Hwa Ko
- Department of Anatomy, College of Medicine, China Medical University, Taichung, Taiwan
| | - Ming-Ling Yang
- Department of Anatomy, School of Medicine, Chung Shan Medical University, Taichung, Taiwan
- Department of Medical Education, Chung Shan Medical University Hospital, Taichung, Taiwan
| | - Su-Chung Youn
- Department of Anatomy, School of Medicine, Chung Shan Medical University, Taichung, Taiwan
- Department of Medical Education, Chung Shan Medical University Hospital, Taichung, Taiwan
| | - Chyn-Tair Lan
- Department of Anatomy, School of Medicine, Chung Shan Medical University, Taichung, Taiwan
- Department of Medical Education, Chung Shan Medical University Hospital, Taichung, Taiwan
- Chyn-Tair Lan, Department of Anatomy, School of Medicine, Chung Shan Medical University, No. 110, Jian-Guo N. R., Sec. 1, Taichung 40201, Taiwan. To-Jung Tseng, Department of Anatomy, School of Medicine, Chung Shan Medical University, No. 110, Jian-Guo N. R., Sec. 1, Taichung 40201, Taiwan.
| | - To-Jung Tseng
- Department of Anatomy, School of Medicine, Chung Shan Medical University, Taichung, Taiwan
- Department of Medical Education, Chung Shan Medical University Hospital, Taichung, Taiwan
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10
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Ramírez GA, Rodríguez F, Herráez P, Castro-Alonso A, Andrada M, Espinosa-de-los-Monteros A. Ultrastructural characterization of normal Merkel cells in the dog. Vet Dermatol 2015; 26:328-33, e68-9. [PMID: 26174874 DOI: 10.1111/vde.12230] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/09/2015] [Indexed: 11/28/2022]
Abstract
BACKGROUND Involvement of Merkel cells (MKs) in different cutaneous diseases as well as in the growth, differentiation and homeostasis of the skin has been previously documented. HYPOTHESIS/OBJECTIVES The aim was to assess the ultrastructural features of MKs in canine skin, including morphometrics, highlighting their similarities with and differences from those described for other mammals. ANIMALS Hard palate, nasal planum, lower lip and whisker pad samples were taken from two healthy young dogs destined for academic purposes. METHODS Ultrathin sections of samples fixed in osmium tetroxide and embedded in Epon 812 resin were stained with uranyl acetate and lead citrate and examined using a JEOL JEM 2010 transmission electron microscope. RESULTS Ultrastructural characteristics included the following: (i) arrangement in clusters in the basal layer of the epidermis, oral mucosa and external follicular root sheath; (ii) inconstant link with nerve terminal; (iii) oval (10.27 ± 1.64 μm major axis) cell shape with large lobulated nuclei (5.98 ± 1.16 μm major axis); (iv) spine-like and thick cytoplasmic processes interdigitating with surrounding keratinocytes; (v) presence of desmosomes in the cell body or at the base of spine-like processes attaching to neighbouring keratinocytes; and (vi) cytoplasm containing loosely arranged intermediate filaments (10.04 ± 1.17 nm) and numerous dense-core granules (100.1 ± 17.12 nm) arranged in the basal portion of the cytoplasm. CONCLUSIONS AND CLINICAL IMPORTANCE This study provides the first complete description of the ultrastructural characteristics of MKs in the dog, enhancing our knowledge of the skin structure in this species and providing a basis for future physiological and pathological studies of the role of these cells in normal and damaged canine tissues.
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Affiliation(s)
- Gustavo A Ramírez
- Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas de Gran Canaria, Campus Universitario Cardones, Arucas, Las Palmas, 45413, Spain
| | - Francisco Rodríguez
- Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas de Gran Canaria, Campus Universitario Cardones, Arucas, Las Palmas, 45413, Spain
| | - Pedro Herráez
- Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas de Gran Canaria, Campus Universitario Cardones, Arucas, Las Palmas, 45413, Spain
| | - Ayoze Castro-Alonso
- Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas de Gran Canaria, Campus Universitario Cardones, Arucas, Las Palmas, 45413, Spain
| | - Marisa Andrada
- Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas de Gran Canaria, Campus Universitario Cardones, Arucas, Las Palmas, 45413, Spain
| | - Antonio Espinosa-de-los-Monteros
- Unit of Histology and Veterinary Pathology, Institute for Animal Health, Veterinary College, University of Las Palmas de Gran Canaria, Campus Universitario Cardones, Arucas, Las Palmas, 45413, Spain
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Nakatani M, Maksimovic S, Baba Y, Lumpkin EA. Mechanotransduction in epidermal Merkel cells. Pflugers Arch 2014; 467:101-8. [PMID: 25053537 DOI: 10.1007/s00424-014-1569-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Accepted: 06/27/2014] [Indexed: 12/24/2022]
Abstract
The cellular and molecular basis of vertebrate touch reception remains least understood among the traditional five senses. Somatosensory afferents that innervate the skin encode distinct tactile qualities, such as flutter, slip, and pressure. Gentle touch is thought to be transduced by somatosensory afferents whose tactile end organs selectively filter mechanical stimuli. These tactile end organs comprise afferent terminals in association with non-neuronal cell types such as Merkel cells, keratinocytes, and Schwann cells. An open question is whether these non-neuronal cells serve primarily as passive mechanical filters or whether they actively participate in mechanosensory transduction. This question has been most extensively studied in Merkel cells, which are epidermal cells that complex with sensory afferents in regions of high tactile acuity such as fingertips, whisker follicles, and touch domes. Merkel cell-neurite complexes mediate slowly adapting type I (SAI) responses, which encode sustained pressure and represent object features with high fidelity. How Merkel cells contribute to unique SAI firing patterns has been debated for decades; however, three recent studies in rodent models provide some direct answers. First, whole-cell recordings demonstrate that Merkel cells are touch-sensitive cells with fast, mechanically activated currents that require Piezo2. Second, optogenetics and intact recordings show that Merkel cells mediate sustained SAI firing. Finally, loss-of-function studies in transgenic mouse models reveal that SAI afferents are also touch sensitive. Together, these studies identify molecular mechanisms of mechanotransduction in Merkel cells, reveal unexpected functions for these cells in touch, and support a revised, two-receptor site model of mechanosensory transduction.
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Affiliation(s)
- Masashi Nakatani
- Department of Dermatology, Columbia University, 1150 St. Nicholas Avenue, room 302B, New York, NY, 10032, USA
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Xiao Y, Williams JS, Brownell I. Merkel cells and touch domes: more than mechanosensory functions? Exp Dermatol 2014; 23:692-5. [PMID: 24862916 DOI: 10.1111/exd.12456] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/23/2014] [Indexed: 12/19/2022]
Abstract
The touch dome (TD) is an innervated structure in the epidermis of mammalian skin. Composed of specialized keratinocytes and neuroendocrine Merkel cells, the TD has distinct molecular characteristics compared to the surrounding epidermal keratinocytes. Much of the research on Merkel cell function has focused on their role in mechanosensation, specifically light touch. Recently, more has been discovered about Merkel cell molecular characteristics and their cells of origin. Here we review Merkel cell and TD biology, and discuss potential functions beyond mechanosensation.
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Affiliation(s)
- Ying Xiao
- Dermatology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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Maksimovic S, Baba Y, Lumpkin EA. Neurotransmitters and synaptic components in the Merkel cell-neurite complex, a gentle-touch receptor. Ann N Y Acad Sci 2013; 1279:13-21. [PMID: 23530998 DOI: 10.1111/nyas.12057] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Merkel cells are an enigmatic group of rare cells found in the skin of vertebrates. Most make contacts with somatosensory afferents to form Merkel cell-neurite complexes, which are gentle-touch receptors that initiate slowly adapting type I responses. The function of Merkel cells within the complex remains debated despite decades of research. Numerous anatomical studies demonstrate that Merkel cells form synaptic-like contacts with sensory afferent terminals. Moreover, recent molecular analysis reveals that Merkel cells express dozens of presynaptic molecules that are essential for synaptic vesicle release in neurons. Merkel cells also produce a host of neuroactive substances that can act as fast excitatory neurotransmitters or neuromodulators. Here, we review the major neurotransmitters found in Merkel cells and discuss these findings in relation to the potential function of Merkel cells in touch reception.
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Affiliation(s)
- Srdjan Maksimovic
- Department of Dermatology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
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Hale MW, Raison CL, Lowry CA. Integrative physiology of depression and antidepressant drug action: implications for serotonergic mechanisms of action and novel therapeutic strategies for treatment of depression. Pharmacol Ther 2012; 137:108-18. [PMID: 23017938 DOI: 10.1016/j.pharmthera.2012.09.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Accepted: 09/10/2012] [Indexed: 11/15/2022]
Abstract
Major depressive disorder (MDD) is predicted to be the second leading cause of disability worldwide by the year 2020. Currently available treatments for MDD are suboptimal. Only 50% of MDD patients recover in less than 12 weeks with adequate treatment, and up to 20% of patients will fail to adequately respond to all currently available interventions. Moreover, current treatments come at the cost of significant central nervous system (CNS) side effects, further highlighting the need for more effective treatments with fewer side effects. A greater mechanistic understanding of MDD and the actions of antidepressant drugs would provide opportunities for development of novel therapeutic approaches to treatment. With this aim in mind, we explore the novel, but empirically supported, hypothesis that an evolutionarily ancient thermoafferent pathway, signaling via the spinoparabrachial pathway from serotonergic sensory cells in the skin and other epithelial linings to serotonergic neurons and depression-related circuits in the brain, is dysfunctional in MDD and that antidepressant therapies, including antidepressant drugs and exercise, act by restoring its function.
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Affiliation(s)
- Matthew W Hale
- School of Psychological Science, La Trobe University, Melbourne 3086, Australia
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Demetriou SK, Ona-Vu K, Sullivan EM, Dong TK, Hsu SW, Oh DH. Defective DNA repair and cell cycle arrest in cells expressing Merkel cell polyomavirus T antigen. Int J Cancer 2012; 131:1818-27. [PMID: 22261839 DOI: 10.1002/ijc.27440] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Accepted: 01/03/2012] [Indexed: 11/09/2022]
Abstract
The pathways by which Merkel cell polyomavirus (MCV) infection contributes to the formation of Merkel cell carcinomas are important for understanding the pathogenesis of these cancers. We hypothesized that MCV T antigen suppresses normal responses to ultraviolet radiation (UVR)-induced DNA damage. An MCV-infected cell line (MKL-1) exhibited UVR hypersensitivity, impaired repair of DNA lesions and cell cycle arrest after UVR, as well as reduced levels of the DNA damage recognition protein, XPC. When ectopically expressed in uninfected UISO cells, mutant but not wild-type T antigen resulted in loss of repair of UVR-induced cyclobutane pyrimidine dimers and reductions in XPC, p53 and p21 levels, whereas both wild-type and mutant T antigen inhibited cell cycle arrest after UVR. Similarly, only mutant T antigen in normal fibroblasts inhibited DNA repair and XPC expression, while both mutant and wild-type T antigens produced cell cycle dysregulation. Wild-type T antigen expression produced large T, 57 kT and small T antigens while mutant T antigen was only detectable as a truncated large T antigen protein. Expression of wild-type large T antigen but not small T antigen inhibited the G1 checkpoint in UISO cells, but neither wild-type large T nor small T antigens affected DNA repair, suggesting that large T antigen generates cell cycle defects, and when mutated may also impair DNA repair. These results indicate that T antigen expression by MCV can inhibit key responses to UVR-induced DNA damage and suggest that progressive MCV-mediated abrogation of genomic stability may be involved in Merkel cell carcinogenesis.
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Importance of non-selective cation channel TRPV4 interaction with cytoskeleton and their reciprocal regulations in cultured cells. PLoS One 2010; 5:e11654. [PMID: 20657843 PMCID: PMC2906515 DOI: 10.1371/journal.pone.0011654] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Accepted: 06/15/2010] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND TRPV4 and the cellular cytoskeleton have each been reported to influence cellular mechanosensitive processes as well as the development of mechanical hyperalgesia. If and how TRPV4 interacts with the microtubule and actin cytoskeleton at a molecular and functional level is not known. METHODOLOGY AND PRINCIPAL FINDINGS We investigated the interaction of TRPV4 with cytoskeletal components biochemically, cell biologically by observing morphological changes of DRG-neurons and DRG-neuron-derived F-11 cells, as well as functionally with calcium imaging. We find that TRPV4 physically interacts with tubulin, actin and neurofilament proteins as well as the nociceptive molecules PKCepsilon and CamKII. The C-terminus of TRPV4 is sufficient for the direct interaction with tubulin and actin, both with their soluble and their polymeric forms. Actin and tubulin compete for binding. The interaction with TRPV4 stabilizes microtubules even under depolymerizing conditions in vitro. Accordingly, in cellular systems TRPV4 colocalizes with actin and microtubules enriched structures at submembranous regions. Both expression and activation of TRPV4 induces striking morphological changes affecting lamellipodial, filopodial, growth cone, and neurite structures in non-neuronal cells, in DRG-neuron derived F11 cells, and also in IB4-positive DRG neurons. The functional interaction of TRPV4 and the cytoskeleton is mutual as Taxol, a microtubule stabilizer, reduces the Ca2+-influx via TRPV4. CONCLUSIONS AND SIGNIFICANCE TRPV4 acts as a regulator for both, the microtubule and the actin. In turn, we describe that microtubule dynamics are an important regulator of TRPV4 activity. TRPV4 forms a supra-molecular complex containing cytoskeletal proteins and regulatory kinases. Thereby it can integrate signaling of various intracellular second messengers and signaling cascades, as well as cytoskeletal dynamics. This study points out the existence of cross-talks between non-selective cation channels and cytoskeleton at multiple levels. These cross talks may help us to understand the molecular basis of the Taxol-induced neuropathic pain development commonly observed in cancer patients.
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Boulais N, Pennec JP, Lebonvallet N, Pereira U, Rougier N, Dorange G, Chesné C, Misery L. Rat Merkel cells are mechanoreceptors and osmoreceptors. PLoS One 2009; 4:e7759. [PMID: 19898622 PMCID: PMC2770322 DOI: 10.1371/journal.pone.0007759] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Accepted: 10/13/2009] [Indexed: 01/15/2023] Open
Abstract
Merkel cells (MCs) associated with nerve terminals constitute MC-neurite complexes, which are involved in slowly-adapting type I mechanoreception. Although MCs are known to express voltage-gated Ca2+ channels and hypotonic-induced membrane deformation is known to lead to Ca2+ transients, whether MCs initiate mechanotransduction is currently unknown. To answer to this question, rat MCs were transfected with a reporter vector, which enabled their identification. Their properties were investigated through electrophysiological studies. Voltage-gated K+, Ca2+ and Ca2+-activated K+ (KCa) channels were identified, as previously described. Here, we also report the activation of Ca2+ channels by histamine and their inhibition by acetylcholine. As a major finding, we demonstrated that direct mechanical stimulations induced strong inward Ca2+ currents in MCs. Depolarizations were dependent on the strength and the length of the stimulation. Moreover, touch-evoked currents were inhibited by the stretch channel antagonist gadolinium. These data confirm the mechanotransduction capabilities of MCs. Furthermore, we found that activation of the osmoreceptor TRPV4 in FM1-43-labeled MCs provoked neurosecretory granule exocytosis. Since FM1-43 blocks mechanosensory channels, this suggests that hypo-osmolarity activates MCs in the absence of mechanotransduction. Thus, mechanotransduction and osmoreception are likely distinct pathways.
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Affiliation(s)
- Nicholas Boulais
- University of Brest, European University of Brittany, Laboratory on Nervous Factors and Tissular Structure, EA4326, CHU, Brest, France
- Bioprédic International, Rennes, France
| | - Jean-Pierre Pennec
- University of Brest, European University of Brittany, Laboratory on Nervous Factors and Tissular Structure, EA4326, CHU, Brest, France
| | - Nicolas Lebonvallet
- University of Brest, European University of Brittany, Laboratory on Nervous Factors and Tissular Structure, EA4326, CHU, Brest, France
| | - Ulysse Pereira
- University of Brest, European University of Brittany, Laboratory on Nervous Factors and Tissular Structure, EA4326, CHU, Brest, France
| | | | - Germaine Dorange
- University of Brest, European University of Brittany, Laboratory on Nervous Factors and Tissular Structure, EA4326, CHU, Brest, France
| | | | - Laurent Misery
- University of Brest, European University of Brittany, Laboratory on Nervous Factors and Tissular Structure, EA4326, CHU, Brest, France
- * E-mail:
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