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

Autor(es)

Marcelino da Silva, Elaine Zayas ; Freitas-Filho, Edismauro Garcia ; de Souza-Junior, Devandir Antonio ; Pinto DaSilva, Luis Lamberti ; Jamur, Maria Celia ; Oliver, Constance

• Tipo de documento: Artigo Científico
• Fonte: PLoS One; v. 12, n. 3 MAR 8 2017.
• Citações Web of Science: 2

Resumo

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)

• Processo FAPESP: 14/11396-5 - O envolvimento do complexo adaptador AP-3 na secreção regulada em mastócitos
• Beneficiário: Constance Oliver
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 13/12861-0 - O papel de gangliosídeos específicos como moduladores da liberação de mediadores de mastócitos
• Beneficiário: Edismauro Garcia Freitas Filho
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 09/54013-0 - Correlação funcional entre mastócitos e a angiogênese tumoral
• Beneficiário: Maria Célia Jamur
• Modalidade de apoio: Auxílio à Pesquisa - Programa Equipamentos Multiusuários