title: Immunohistochemical analysis of secretoglobin SCGB 2A1 expression in human ocular glands and tissues.
abstract: Human secretoglobin (SCGB) 2A1 (or lipophilin C, lacryglobin, mammaglobin B) is a small protein of unknown function that forms heterodimers with secretoglobin 1D1 (lipophilin A) in tears. SCGB 2A1 is homologous to mammaglobin (mammaglobin A) and the C3 component of prostatein, the major secretory protein of the rat ventral prostate. Androgen-dependent expression of SCGB 2A1 has been observed in the prostate. Besides identification of SCGB 2A1 in the tear proteome only its mRNA had been detected in the lacrimal gland. Here, we report expression of SCGB 2A1 in all ocular glands and in the keratinized stratified squamous epithelium of the eyelid as well as in the stratified epithelium of the conjunctiva and in the orbicularis oculi muscle. Almost all of these tissues are also known to express the androgen receptor. Therefore, we conclude that presence of the androgen signalling machinery could be the main general determinant of SCGB 2A1 expression. Implications of the presence in tear fluid of an androgen-regulated secretoglobin, which most likely binds hydrophobic ligands, for tear film lipid layer formation and function is discussed.
authors.affiliation: Institute of Anatomy, Ludwig-Maximilians-University of Munich, Pettenkoferstrasse 11, 80336, Munich, Germany.
authors.forename: Mechthild
authors.initials: M
authors.lastname: Stoeckelhuber
authors.forename: Elisabeth M
authors.initials: EM
authors.lastname: Messmer
authors.forename: Corina
authors.initials: C
authors.lastname: Schmidt
authors.forename: Fei
authors.initials: F
authors.lastname: Xiao
authors.forename: Christoph
authors.initials: C
authors.lastname: Schubert
authors.forename: Jörg
authors.initials: J
authors.lastname: Klug
mesh_terms: D000368:Aged; D000728:Androgens / Q000502:physiology; D015153:Blotting, Western; D004848:Epithelium / Q000378:metabolism; D005088:Exocrine Glands / Q000378:metabolism*; D005123:Eye / Q000166:cytology / Q000378:metabolism*; D005143:Eyelids / Q000166:cytology / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007765:Lacrimal Apparatus / Q000166:cytology / Q000378:metabolism; D008297:Male; D060788:Mammaglobin B; D008537:Meibomian Glands / Q000166:cytology / Q000378:metabolism; D009185:Myelin Proteins / Q000096:biosynthesis* / Q000235:genetics; D009915:Orbit / Q000378:metabolism; D011510:Proteolipids / Q000096:biosynthesis* / Q000235:genetics; D060765:Secretoglobins; D013666:Tears / Q000737:chemistry; D014598:Uteroglobin / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D000728:Androgens; D060788:Mammaglobin B; D009185:Myelin Proteins; D011510:Proteolipids; C556463:SCGB1D1 protein, human; C556467:SCGB2A1 protein, human; D060765:Secretoglobins; D014598:Uteroglobin