Dendritic cells (DCs) are innate immune cells that regulate both immune homeostasis as well as antigen driven immune responses. The functions of DCs are highly regulated by signals initiated by Toll-like receptors (TLRs). Consequently, intracellular molecules that regulate TLR signaling pathways are pivotal for regulating host immune responses. We have recently found that A20 is a ubiquitin modifying enzyme that restricts toll-like receptor (TLR) induced signals. We are studying the roles of A20 expression in DCs in regulating immune homeostasis and responses. To accomplish this, we have generated two strains of gene targeted mice: one that disrupts the A20 gene in all cells and one in which a "floxed" allele of A20 has been targeted to the endogenous A20 locus. We have interbred the "floxed" mice with a novel strain of CD11-Cre transgenic mouse line that expresses Cre enzyme with high selectivity and specificity in DCs. These compound A20flox/flox CD11c-Cre mice will thus provide us with a very powerful and novel reagent for studying the role of A20 expression in DCs in regulating immune homeostasis and immune responses. We propose to use these A20flox/flox CD11-cre compound mice, as well as cells derived from both strains of mice, to determine how A20 expression in DCs regulates their responses to TLR ligands in vitro and in vivo.
The first aim will focus upon understanding the cell biology and biochemistry underlying A20's roles in regulating TLR signaling in DCs, and will elucidate the cell-autonomous functions of DCs that are regulated by A20.
The second aim will utilize A20flox/flox CD11c-Cre mice to determine how A20 expression in DCs regulates their homeostasis and activation in vivo.
This second aim will also interrogate how A20 expression in DCs regulates peripheral tolerance and immune responses.

Public Health Relevance

This project focuses on a potent endogenous anti-inflammatory protein called A20, and how it regulates dendritic cell functions in vivo. As dendritic cells are powerful regulators of immune responses, and as A20 plays critical roles in regulating dendritic cell functions, understanding how A20 regulates dendritic cells and immune responses could significantly enhance the development of therapies for inflammatory diseases and thus have major benefits for public health.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK071939-09
Application #
8536787
Study Section
Innate Immunity and Inflammation Study Section (III)
Program Officer
Spain, Lisa M
Project Start
2005-09-01
Project End
2015-08-31
Budget Start
2013-09-01
Budget End
2014-08-31
Support Year
9
Fiscal Year
2013
Total Cost
$467,367
Indirect Cost
$162,676
Name
University of California San Francisco
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
094878337
City
San Francisco
State
CA
Country
United States
Zip Code
94143
Lu, Timothy T; Onizawa, Michio; Hammer, Gianna E et al. (2013) Dimerization and ubiquitin mediated recruitment of A20, a complex deubiquitinating enzyme. Immunity 38:896-905
Tavares, Rita M; Turer, Emre E; Liu, Chih L et al. (2010) The ubiquitin modifying enzyme A20 restricts B cell survival and prevents autoimmunity. Immunity 33:181-91
Oshima, Shigeru; Turer, Emre E; Callahan, Joseph A et al. (2009) ABIN-1 is a ubiquitin sensor that restricts cell death and sustains embryonic development. Nature 457:906-9
Turer, Emre E; Tavares, Rita M; Mortier, Erwan et al. (2008) Homeostatic MyD88-dependent signals cause lethal inflamMation in the absence of A20. J Exp Med 205:451-64
Hutti, Jessica E; Turk, Benjamin E; Asara, John M et al. (2007) IkappaB kinase beta phosphorylates the K63 deubiquitinase A20 to cause feedback inhibition of the NF-kappaB pathway. Mol Cell Biol 27:7451-61