title: Controversies in RELN/reelin expression in otosclerosis.
abstract: Several studies have reported a potential genetic association between disease-specific single nucleotide polymorphism (SNPs) of RELN and otosclerosis and confirmed RELN expression in human stapes footplates. These are conflicting results, since RELN expression has been attributed exclusively to neural tissues and to odontoblasts. Otosclerosis is a disease of complex bone remodeling disorder, which is limited to the human otic capsule. Genetic predisposition has long been suspected, however, the pathogenesis remained unclear. Ankylotic stapes footplates (n = 85), cortical bone fragments (n = 4), hearing ossicles (n = 2) and human brain tissue specimens (n = 4) were processed to RELN-specific RT-PCR and reelin-specific immunofluorescent assay (IFA). The first group of ankylotic stapes footplates (n = 22) showed a consistent positive reaction against reelin by IFA; however, RELN-specific mRNA could not be detected in the second, RT-PCR group (n = 63). Brain specimens were characterized by robust expression of reelin (n = 2) and RELN-specific mRNA (n = 2). In case of bone-specific controls (n = 6), reelin/RELN expression was excluded obviously. Concerning current observations, RELN gene does not show active expression in adult stapes footplates. Since, the otic capsule surrounds a special neural structure (membranous labyrinth), reelin might play a coordinative role in the early embryonic stage of development. As being a part of the otic capsule, stapes footplate might be characterized by persisting reelin detectability without mRNA expression. Between these conditions, the etiologic role of RELN is questionable in the pathogenesis of otosclerosis.
authors.affiliation: Department of Otolaryngology and Head and Neck Surgery, Medical and Health Science Center, University of Debrecen, Debrecen, Nagyerdei Krt. 98, 4032, Hungary.
authors.forename: Péter
authors.initials: P
authors.lastname: Csomor
authors.forename: István
authors.initials: I
authors.lastname: Sziklai
authors.forename: Tamás
authors.initials: T
authors.lastname: Karosi
mesh_terms: D000328:Adult; D001253:Astrocytes / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics*; D016326:Extracellular Matrix Proteins / Q000235:genetics*; D005260:Female; D015870:Gene Expression / Q000235:genetics*; D006801:Humans; D051457:Hyaline Cartilage / Q000378:metabolism; D008297:Male; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009836:Oligodendroglia / Q000378:metabolism; D010040:Otosclerosis / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D000091042:Reelin Protein; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012697:Serine Endopeptidases / Q000235:genetics*; D012886:Skull / Q000378:metabolism; D013199:Stapes / Q000378:metabolism; D014722:Vestibule, Labyrinth / Q000378:metabolism
chemical_list: D015816:Cell Adhesion Molecules, Neuronal; D016326:Extracellular Matrix Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D000091042:Reelin Protein; C000717127:RELN protein, human; D012697:Serine Endopeptidases