Apoptosis-associated protein expression in human salivary gland morphogenesis.
OBJECTIVE
Salivary gland (SG) development is based on branching morphogenesis, in which programmed cell death has been proposed to play a role in cell signalling and organ shaping. In the mouse salivary gland apoptosis has been suggested to play a key role in lumen formation, removing the central cells of the epithelial stalks. Here we analyse the expression of several anti- and pro-regulators of apoptosis during human SG development in a range of developmental stages.


METHODS
Foetal SGs obtained from the University of São Paulo were analysed by immunohistochemistry to assess the expression of apoptosis-associated proteins: caspases (caspase-6, -7, -9 and cleaved caspase-3), Bcl-2 family members (Bax, Bak, Bad, Bid, Bcl-2, Bcl-x and Bcl-xL), Survivin (BIRC5), Cytochrome C and Apaf-1.


RESULTS
Nuclear expression of Bax and Bak was identified in presumptive luminal areas at initial stages, while Bcl-xL showed the most relevant anti-apoptotic activity. Caspase-6, -7 and -9 were expressed during all stages, while interestingly cleaved caspase-3 showed no prominent expression, indicating that caspase-7 is the main effector. Apoptosome complex components Apaf-1 and Cytochrome C, as well as survivin were all positive in developing glands.


CONCLUSIONS
The particular expression pattern of several apoptotic regulators in human SG development suggests the existence of a fundamental role for apoptosis during duct formation. The absence of Bad and Bid expressions indicates that the instrinsic pathway is more active then the extrinsic during human gland formation. The subcellular localisation of intrinsic-apoptosis proteins correlated with apoptotic activity, but also suggested additional non-apoptotic functions.
Department of Stomatology, Dental School, University of Sao Paulo, Brazil Av Professor Lineu Prestes, 2227, Cidade Universitária, 05508-000 São Paulo, SP, Brazil. Electronic address: tathyane.teshima@usp.br.
Tathyane H N
TH
Teshima
Department of Pathology, A.C. Camargo Hospital, Sao Paulo, Brazil R. Taguá, 400, Liberdade, 01508-010 São Paulo, SP, Brazil, Brazil. Electronic address: reianez@gmail.com.
Renata C F
RC
Ianez
Department of Pathology, A.C. Camargo Hospital, Sao Paulo, Brazil R. Taguá, 400, Liberdade, 01508-010 São Paulo, SP, Brazil, Brazil. Electronic address: claumcc@terra.com.br.
Claudia M
CM
Coutinho-Camillo
Department of Craniofacial Development and Stem Cell Biology, King's College London, UK Guy's Hospital, London Bridge, SE1 9RT London, United Kingdom, United Kingdom. Electronic address: abigail.tucker@kcl.ac.uk.
Abigail S
AS
Tucker
Department of Stomatology, Dental School, University of Sao Paulo, Brazil Av Professor Lineu Prestes, 2227, Cidade Universitária, 05508-000 São Paulo, SP, Brazil; Department of Pathology, A.C. Camargo Hospital, Sao Paulo, Brazil R. Taguá, 400, Liberdade, 01508-010 São Paulo, SP, Brazil, Brazil. Electronic address: silvialourenco@usp.br.
Silvia V
SV
Lourenço
D000818:Animals; D017209:Apoptosis / Q000235:genetics / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D053477:Apoptotic Protease-Activating Factor 1 / Q000378:metabolism; D020169:Caspases / Q000096:biosynthesis / Q000378:metabolism; D045304:Cytochromes c / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D009024:Morphogenesis / Q000502:physiology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis / Q000378:metabolism; D012469:Salivary Glands / Q000166:cytology* / Q000378:metabolism*; D015398:Signal Transduction; D051020:bcl-X Protein / Q000096:biosynthesis / Q000378:metabolism
C506592:APAF1 protein, human; D051017:Apoptosis Regulatory Proteins; D053477:Apoptotic Protease-Activating Factor 1; D019253:Proto-Oncogene Proteins c-bcl-2; D051020:bcl-X Protein; D045304:Cytochromes c; D020169:Caspases
Apoptosis; Bcl-2 family; Caspases; Development; Human; Salivary glands