Cytotoxic T lymphocytes (CTL) and natural killer (NK) cells exocytose cytotoxic granules to induce apoptosis of virally infected or tumor targets. Cytotoxic granules contain perforin, a pore-forming protein, and a group of serine proteases, called granzymes (Gzm), in a proteoglycan matrix. Perforin and either GzmA or GzmB is sufficient for granule-mediated lysis by CTL, but mice deficient in either Gzm may be impaired in defense against some viral infections. GzmB activates a ubiquitous apoptotic cascade induced by cleavage of caspases and can also directly cleave some key caspase pathway substrates. However, CTL granule mediated cytolysis is virtually unimpaired in the setting of complete caspase blockade. GzmA, the most abundant Gzm, activates a novel caspase-independent apoptotic pathway. The goal of this proposal is to continue to unravel the mechanism of action of GzmA, building on the research accomplished during the previous funding. GzmA, delivered into target cells via perforin, induces single-stranded DNA damage as Nell as apoptotic morphology and loss of cell membrane integrity. A special target of the GzmA cell death pathway is a 270-440 kDa endoplasmic reticulum-associated complex, called the SET complex, which contains three GzmA substrates, the nucleosome assembly protein SET, the DNA bending protein HMG-2 and the apurinic endonuclease (Ape1) in base excision repair (BER). GzmA cleavage of Ape1 makes target cell repair of GzmA-induced damage unlikely. The SET complex also contains the GzmA-activated DNase, NM23-H1, which is activated when GzmA cleaves its specific inhibitor, the SET protein. The competing renewal of this grant will investigate the kinetics of GzmA-mediated damage within target cells; determine the mitochondrial effects of GzmA; identify the remaining components of the SET complex and seek to understand further the role of the SET complex in normal cellular function and in GzmA-mediated cell death; and investigate the effect of GzmA on other DNA repair pathways, besides BER.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI045587-09
Application #
7254918
Study Section
Experimental Immunology Study Section (EI)
Program Officer
Miller, Lara R
Project Start
1999-07-01
Project End
2009-06-30
Budget Start
2007-07-01
Budget End
2008-06-30
Support Year
9
Fiscal Year
2007
Total Cost
$543,035
Indirect Cost
Name
Immune Disease Institute, Inc.
Department
Type
DUNS #
059709394
City
Boston
State
MA
Country
United States
Zip Code
02115
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Yan, Nan; Lieberman, Judy (2011) Gaining a foothold: how HIV avoids innate immune recognition. Curr Opin Immunol 23:21-8
Lieberman, Judy (2010) Granzyme A activates another way to die. Immunol Rev 235:93-104
Yan, Nan; Regalado-Magdos, Ashton D; Stiggelbout, Bart et al. (2010) The cytosolic exonuclease TREX1 inhibits the innate immune response to human immunodeficiency virus type 1. Nat Immunol 11:1005-13
Thiery, Jerome; Walch, Michael; Jensen, Danielle K et al. (2010) Isolation of cytotoxic T cell and NK granules and purification of their effector proteins. Curr Protoc Cell Biol Chapter 3:Unit3.37

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