title: Apoptosis in Early Salivary Gland Duct Morphogenesis and Lumen Formation.
abstract: Salivary glands are essential for the maintenance of oral health by providing lubrication and antimicrobial protection to the mucosal and tooth surfaces. Saliva is modified and delivered to the oral cavity by a complex multifunctional ductal system. During development, these ducts form as solid tubes, which undergo cavitation to create lumens. Apoptosis has been suggested to play a role in this cavitation process along with changes in cell polarity. Here, we show that apoptosis occurs from the very earliest stages of mouse salivary gland development, much earlier than previously reported. Apoptotic cells were observed in the center of the first epithelial stalk at early-stage embryonic day 12.5 (E12.5) according to both TUNEL staining and cleaved caspase 3 immunofluorescence. The presumptive lumen space was highlighted by the colocalization of a predictive lumen marker, cytokeratin 7. At E14.5, as lumens start to form throughout the glands, apoptotic expression decreased while cytokeratin 7 remained positive. In vitro inhibition of all caspases in E12.5 and E13.5 salivary glands resulted in wider ducts, as compared with the controls, and a defect in lumen formation. In contrast, no such defect in lumen formation was observed at E14.5. Our data indicate that apoptosis is involved during early stages of gland formation (E12.5 onward) and appears important for shaping the forming ducts.
authors.affiliation: Department of Stomatology, School of Dentistry, University of Sao Paulo, São Paulo, Brazil.
authors.forename: T H N
authors.initials: TH
authors.lastname: Teshima
authors.affiliation: Department of Craniofacial Development and Stem Cell Biology, King's College London, London, UK.
authors.forename: K L
authors.initials: KL
authors.lastname: Wells
authors.affiliation: Department of Stomatology, School of Dentistry, University of Sao Paulo, São Paulo, Brazil.
authors.forename: S V
authors.initials: SV
authors.lastname: Lourenço
authors.affiliation: Department of Craniofacial Development and Stem Cell Biology, King's College London, London, UK abigail.tucker@kcl.ac.uk.
authors.forename: A S
authors.initials: AS
authors.lastname: Tucker
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D053148:Caspase 3 / Q000032:analysis / Q000187:drug effects; D061945:Caspase Inhibitors / Q000494:pharmacology; D016764:Cell Polarity / Q000502:physiology; D047108:Embryonic Development / Q000502:physiology; D004848:Epithelium / Q000196:embryology; D020287:In Situ Nick-End Labeling; D053552:Keratin-7 / Q000032:analysis; D051379:Mice; D009024:Morphogenesis / Q000502:physiology*; D009924:Organ Culture Techniques; D018987:Salivary Ducts / Q000187:drug effects / Q000196:embryology*; D013363:Submandibular Gland / Q000196:embryology
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D053552:Keratin-7; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C505409:Casp3 protein, mouse; D053148:Caspase 3
keywords: caspases; cell death; developmental biology; embryonic development; keratins; salivary ducts