Advanced search
Start date
(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Adaptor protein-3: A key player in RBL-2H3 mast cell mediator release

Full text
Marcelino da Silva, Elaine Zayas ; Freitas-Filho, Edismauro Garcia ; de Souza-Junior, Devandir Antonio ; Pinto DaSilva, Luis Lamberti ; Jamur, Maria Celia ; Oliver, Constance
Total Authors: 6
Document type: Journal article
Source: PLoS One; v. 12, n. 3 MAR 8 2017.
Web of Science Citations: 2

Mast cell (MC) secretory granules are Lysosome-Related Organelles (LROs) whose biogenesis is associated with the post-Golgi secretory and endocytic pathways in which the sorting of proteins destined for a specific organelle relies on the recognition of sorting signals by adaptor proteins that direct their incorporation into transport vesicles. The adaptor protein 3 (AP-3) complex mediates protein trafficking between the trans-Golgi network (TGN) and late endosomes, lysosomes, and LROs. AP-3 has a recognized role in LROs biogenesis and regulated secretion in several cell types, including many immune cells such as neutrophils, natural killer cells, and cytotoxic T lymphocytes. However, the relevance of AP-3 for these processes in MCs has not been previously investigated. AP-3 was found to be expressed and distributed in a punctate fashion in rat peritoneal mast cells ex vivo. The rat MC line RBL-2H3 was used as a model system to investigate the role of AP-3 in mast cell secretory granule biogenesis and mediator release. By immunofluorescence and immunoelectron microscopy, AP-3 was localized both to the TGN and early endosomes indicating that AP-3 dependent sorting of proteins to MC secretory granules originates in these organ-elles. ShRNA mediated depletion of the AP-3 delta subunit was shown to destabilize the AP-3 complex in RBL-2H3 MCs. AP-3 knockdown significantly affected MC regulated secretion of beta-hexosaminidase without affecting total cellular enzyme levels. Morphometric evaluation of MC secretory granules by electron microscopy revealed that the area of MC secretory granules in AP-3 knockdown MCs was significantly increased, indicating that AP-3 is involved in MC secretory granule biogenesis. Furthermore, AP-3 knockdown had a selective impact on the secretion of newly formed and newly synthesized mediators. These results show for the first time that AP-3 plays a critical role in secretory granule biogenesis and mediator release in MCs. (AU)

FAPESP's process: 14/11396-5 - The role of adaptor protein complex 3 (AP-3) in regulated secretion in mast cells
Grantee:Constance Oliver
Support Opportunities: Regular Research Grants
FAPESP's process: 13/12861-0 - The role of mast cell specific gangliosides in modulating mediator release
Grantee:Edismauro Garcia Freitas Filho
Support Opportunities: Scholarships in Brazil - Master
FAPESP's process: 09/54013-0 - Functional correlation between mast cells and tumor angiogenesis
Grantee:Maria Célia Jamur
Support Opportunities: Multi-user Equipment Program