Natural killer (NK) immune cells are essential for human defense against infection and malignancy. Armed at baseline to mediate cytotoxicity, NK cells survey their environment, precisely targeting their cytolytic effects to individual cancerous or virus-infected cells. Through a tightly regulated step-wise process termed """"""""directed secretion"""""""", NK cells mobilize highly specialized large organelles (lytic granules) to the NK/target cell interface, known as the immune synapse (IS). The proposed work addresses the following three critical challenges to accessing and controlling directed secretion for NK cell cytotoxicity: 1) organizing lytic granules for focused and efficient delivery;2) orchestrating the cortical cytoskeleton to permit lytic granule egress;and 3) facilitating transit of lytic granules to the synaptic membrane. First, lytic granules converge to the microtubule organization center (MTOC) prior to polarizing to the NK cell IS. The proposed work will identify the signal and cellular inputs that drive lytic granule convergence and specifically determine whether convergence makes NK cells more efficient killers, less likely to kill """"""""innocent bystanders"""""""", and more capable of mediating serial kills. Second, current paradigms suggest that lytic granule egress occurs through a single large clearance in the actin cortex. High-resolution imaging modalities, however, suggest that lytic granules exploit smaller, specifically generated hypodense conduits in the filamentous (F)-actin network. Combining highly quantitative imaging with a novel degranulation indicator and innovative human NK cell manipulation techniques, the proposed work will further define the nature and requirement for these conduits for degranulation. Lastly, recently identified NK cell lytic granule-based motor complexes are required for the lytic granule's final approach to the synaptic membrane. Live-cell imaging and adoptive transfer-style experiments using lytic granules and NK cell cortices will define the mechanisms by which lytic granule-associated myosin-IIA enables granules to find, move through, and/or form F-actin conduits. The specific role of the myosin-IIA tail and myosin-IIA phosphorylation in these functions will be tested using a combination of immunological and biochemical assays. In the absence of strict control of directed secretion, NK cells would lose efficiency and indiscriminately kill neighboring tissue and healthy cells, posing a danger to the human host. The proposed work will redefine fundamental paradigms as to how access to cytotoxicity is controlled, define new cellular checkpoints in NK cell function, and provide novel insights into the basic cell biological processes that govern immunity. Better understanding the immunoregulatory mechanisms controlling the precise step-wise progression to cytotoxicity will enable therapeutic manipulation of NK cell function in the context of human disease.

Public Health Relevance

Natural Killer (NK) immune cells precisely target and destroy cancerous and virus-infected cells. The proposed work will define the sub-cellular mechanisms governing the directionality and efficiency of the NK cell killing machinery. Understanding these processes will enable therapeutic control of NK cell defense against malignancy and infection.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Innate Immunity and Inflammation Study Section (III)
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Miller, Lara R
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Baylor College of Medicine
Schools of Medicine
United States
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Mace, Emily M; Bigley, Venetia; Gunesch, Justin T et al. (2017) Biallelic mutations in IRF8 impair human NK cell maturation and function. J Clin Invest 127:306-320
Jacquemet, Guillaume; Paatero, Ilkka; Carisey, Alexandre F et al. (2017) FiloQuant reveals increased filopodia density during breast cancer progression. J Cell Biol 216:3387-3403
Gomes-Silva, Diogo; Mukherjee, Malini; Srinivasan, Madhuwanti et al. (2017) Tonic 4-1BB Costimulation in Chimeric Antigen Receptors Impedes T Cell Survival and Is Vector-Dependent. Cell Rep 21:17-26
Hsu, Hsiang-Ting; Mace, Emily M; Carisey, Alexandre F et al. (2016) NK cells converge lytic granules to promote cytotoxicity and prevent bystander killing. J Cell Biol 215:875-889
Hegde, Meenakshi; Mukherjee, Malini; Grada, Zakaria et al. (2016) Tandem CAR T cells targeting HER2 and IL13R?2 mitigate tumor antigen escape. J Clin Invest 126:3036-52
Mace, Emily M; Orange, Jordan S (2016) Genetic Causes of Human NK Cell Deficiency and Their Effect on NK Cell Subsets. Front Immunol 7:545
Netter, Petra; Chan, Sanny K; Banerjee, Pinaki P et al. (2016) A novel Rab27a mutation binds melanophilin, but not Munc13-4, causing immunodeficiency without albinism. J Allergy Clin Immunol 138:599-601.e3
Angelo, Laura S; Banerjee, Pinaki P; Monaco-Shawver, Linda et al. (2015) Practical NK cell phenotyping and variability in healthy adults. Immunol Res 62:341-56
Watkin, Levi B; Jessen, Birthe; Wiszniewski, Wojciech et al. (2015) COPA mutations impair ER-Golgi transport and cause hereditary autoimmune-mediated lung disease and arthritis. Nat Genet 47:654-60
Mace, Emily M; Orange, Jordan S (2015) Insights into primary immune deficiency from quantitative microscopy. J Allergy Clin Immunol 136:1150-62

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