Mapping the distribution of stem/progenitor cells across the mouse middle ear during homeostasis and inflammation

ABSTRACT The middle ear epithelium is derived from neural crest and endoderm, which line distinct regions of the middle ear cavity. Here, we investigate the distribution of putative stem cell markers in the middle ear, combined with an analysis of the location of label-retaining cells (LRCs) to create a map of the middle ear mucosa. We show that proliferating cells and LRCs were associated with specific regions of the ear epithelium, concentrated in the hypotympanum at the base of the auditory bulla and around the ear drum. Sox2 was widely expressed in the endodermally derived ciliated pseudostratified epithelium of the hypotympanum. This part of the middle ear showed high levels of Wnt activity, as indicated by the expression of Axin2, a readout of Wnt signalling. Keratin 5 showed a more restricted expression within the basal cells of this region, with very little overlap between the Sox2- and keratin 5-positive epithelium, indicating that these genes mark distinct populations. Little expression of Sox2 or keratin 5 was observed in the neural crest-derived middle ear epithelium that lined the promontory, except in cases of otitis media when this epithelium underwent hyperplasia. This study lays the foundation for furthering our understanding of homeostasis and repair in the middle ear. Summary: Neural crest- and endoderm-derived parts of the middle ear epithelium have distinct patterns of proliferation and distribution of keratin 5 and Sox2 that may impact on response during inflammation.

[1]  Ping Chen,et al.  Cilia distribution and polarity in the epithelial lining of the mouse middle ear cavity , 2017, Scientific Reports.

[2]  Steve D. M. Brown,et al.  An in vitro model of murine middle ear epithelium , 2016, Disease Models & Mechanisms.

[3]  K. Lim,et al.  Latent progenitor cells as potential regulators for tympanic membrane regeneration , 2015, Scientific Reports.

[4]  Jennifer C. Fuchs,et al.  A defect in early myogenesis causes Otitis media in two mouse models of 22q11.2 Deletion Syndrome , 2014, Human molecular genetics.

[5]  Jennifer C. Fuchs,et al.  Hearing Loss in a Mouse Model of 22q11.2 Deletion Syndrome , 2013, PloS one.

[6]  M. Dattani,et al.  Sox2(+) stem/progenitor cells in the adult mouse pituitary support organ homeostasis and have tumor-inducing potential. , 2013, Cell stem cell.

[7]  A. Tucker,et al.  Dual Origin of the Epithelium of the Mammalian Middle Ear , 2013, Science.

[8]  K. Hochedlinger,et al.  Sox2+ stem cells contribute to all epithelial lineages of the tooth via Sfrp5+ progenitors. , 2012, Developmental cell.

[9]  Federico Marchetti,et al.  Burden of Disease Caused by Otitis Media: Systematic Review and Global Estimates , 2012, PloS one.

[10]  K. Hochedlinger,et al.  Sox2(+) adult stem and progenitor cells are important for tissue regeneration and survival of mice. , 2011, Cell stem cell.

[11]  H. Rask-Andersen,et al.  Localization of Progenitor/Stem Cells in the Human Tympanic Membrane , 2010, Audiology and Neurotology.

[12]  Scott H Randell,et al.  Airway basal stem cells: a perspective on their roles in epithelial homeostasis and remodeling , 2010, Disease Models & Mechanisms.

[13]  J. Linden,et al.  Defects in middle ear cavitation cause conductive hearing loss in the Tcof1 mutant mouse. , 2010, Human molecular genetics.

[14]  J. Whitsett,et al.  Sox2 Is Required for Maintenance and Differentiation of Bronchiolar Clara, Ciliated, and Goblet Cells , 2009, PloS one.

[15]  I. Burtscher,et al.  Sox17‐2A‐iCre: A knock‐in mouse line expressing Cre recombinase in endoderm and vascular endothelial cells , 2009, Genesis.

[16]  Scott H. Randell,et al.  Basal cells as stem cells of the mouse trachea and human airway epithelium , 2009, Proceedings of the National Academy of Sciences.

[17]  P. Sharpe,et al.  Expression of Axin2 indicates a role for canonical Wnt signaling in development of the crown and root during pre‐ and postnatal tooth development , 2009, Developmental dynamics : an official publication of the American Association of Anatomists.

[18]  R. Schwartz,et al.  Multiple roles for Sox2 in the developing and adult mouse trachea , 2009, Development.

[19]  R. Nusse.  Wnt signaling and stem cell control , 2008, Cell Research.

[20]  R. Lovell-Badge,et al.  SOX2-expressing progenitor cells generate all of the major cell types in the adult mouse pituitary gland , 2008, Proceedings of the National Academy of Sciences.

[21]  Zheng-min Wang,et al.  [Epidermal stem cells in the tympanic membrane]. , 2004, Zhonghua er bi yan hou ke za zhi.

[22]  Joe C. Adams,et al.  Full spectrum of malformations in velo-cardio-facial syndrome/DiGeorge syndrome mouse models by altering Tbx1 dosage. , 2004, Human molecular genetics.

[23]  A. Atef,et al.  Ciliary count in chronic suppurative otitis media: comparative quantitative study between mucosal and squamous types using scanning electron microscopy and image analysis. , 2004, The Journal of laryngology and otology.

[24]  Simon C Watkins,et al.  In vivo differentiation potential of tracheal basal cells: evidence for multipotent and unipotent subpopulations. , 2004, American journal of physiology. Lung cellular and molecular physiology.

[25]  Hans Clevers,et al.  Negative Feedback Loop of Wnt Signaling through Upregulation of Conductin/Axin2 in Colorectal and Liver Tumors , 2002, Molecular and Cellular Biology.

[26]  P. Scambler,et al.  Tbx1 haploinsufficiency in the DiGeorge syndrome region causes aortic arch defects in mice , 2001, Nature.

[27]  A. McMahon,et al.  Modification of gene activity in mouse embryos in utero by a tamoxifen-inducible form of Cre recombinase , 1998, Current Biology.

[28]  P. Jap,et al.  The structure of the middle ear epithelium of the rat and the effect of Eustachian tube obstruction , 1984, The Histochemical Journal.

[29]  D. Lim,et al.  Ultrastructural Pathology of the Middle Ear Mucosa in Serous Otitis Media , 1971, The Annals of otology, rhinology, and laryngology.

[30]  J. Sadé.  Middle ear mucosa. , 1966, Archives of otolaryngology.

[31]  Philippe Soriano.  Generalized lacZ expression with the ROSA26 Cre reporter strain , 1999, Nature Genetics.

[32]  D. Lim,et al.  Ultrastructure of the eustachian tube and middle ear mucosa in the guinea pig. , 1967, Acta oto-laryngologica.