title: Protein kinase D1/2 is involved in the maturation of multivesicular bodies and secretion of exosomes in T and B lymphocytes.
abstract: Multivesicular bodies (MVBs) are endocytic compartments that enclose intraluminal vesicles (ILVs) formed by inward budding from the limiting membrane of endosomes. In T lymphocytes, these ILV contain Fas ligand (FasL) and are secreted as 'lethal exosomes' following activation-induced fusion of the MVB with the plasma membrane. Diacylglycerol (DAG) and diacylglycerol kinase α (DGKα) regulate MVB maturation and polarized traffic, as well as subsequent secretion of pro-apoptotic exosomes, but the molecular basis underlying these phenomena remains unclear. Here we identify protein kinase D (PKD) family members as DAG effectors involved in MVB genesis and secretion. We show that the inducible secretion of exosomes is enhanced when a constitutively active PKD1 mutant is expressed in T lymphocytes, whereas exosome secretion is impaired in PKD2-deficient mouse T lymphoblasts and in PKD1/3-null B cells. Analysis of PKD2-deficient T lymphoblasts showed the presence of large, immature MVB-like vesicles and demonstrated defects in cytotoxic activity and in activation-induced cell death. Using pharmacological and genetic tools, we show that DGKα regulates PKD1/2 subcellular localization and activation. Our studies demonstrate that PKD1/2 is a key regulator of MVB maturation and exosome secretion, and constitutes a mediator of the DGKα effect on MVB secretory traffic.
authors.affiliation: Departamento de Bioquímica, Instituto de Investigaciones Biomédicas Alberto Sols CSIC-UAM Madrid, Madrid, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Mazzeo
authors.affiliation: Departamento de Bioquímica, Instituto de Investigaciones Biomédicas Alberto Sols CSIC-UAM Madrid, Madrid, Spain.
authors.forename: V
authors.initials: V
authors.lastname: Calvo
authors.affiliation: Departamento de Bioquímica, Instituto de Investigaciones Biomédicas Alberto Sols CSIC-UAM Madrid, Madrid, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Alonso
authors.affiliation: Department of Immunology and Oncology, Centro Nacional de Biotecnología CSIC, Madrid, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Mérida
authors.affiliation: Departamento de Bioquímica, Instituto de Investigaciones Biomédicas Alberto Sols CSIC-UAM Madrid, Madrid, Spain.
authors.forename: M
authors.identifier: http://orcid.org/0000-0002-7701-1002
authors.initials: M
authors.lastname: Izquierdo
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism; D016923:Cell Death / Q000235:genetics*; D019852:Diacylglycerol Kinase / Q000235:genetics* / Q000378:metabolism; D055354:Exosomes / Q000235:genetics / Q000378:metabolism; D053222:Fas Ligand Protein; D051379:Mice; D057146:Multivesicular Bodies / Q000235:genetics / Q000378:metabolism; D011493:Protein Kinase C / Q000235:genetics* / Q000378:metabolism; D000091283:Protein Kinase D2; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism
chemical_list: D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D000091283:Protein Kinase D2; D011494:Protein Kinases; D019852:Diacylglycerol Kinase; C089212:protein kinase D; D011493:Protein Kinase C