Faculty Appointments: 
Associate Professor of Pathology and Laboratory Medicine at University of Pennsylvania School of Medicine (2003– present)
(267) 426-5410
Office Location: 
Department of Pathology and Laboratory Medicine Children's Hospital of Philadelphia Perelman School of Medicine University of Pennsylvania 816D Abramson Research Center 3615 Civic Center Blvd.

Research in the lab centers on the role of the cytoskeleton in T cell and dendritic cell function. In particular, we are studying the role of actin binding proteins such as ezrin, moesin, fascin and alpha-actinin in modulating cell signaling and cell migration via changes in cell stiffness and ligand mobility.


Research in our lab addresses the cell biological mechanisms through which regulated actin dynamics promote the function of T cells and antigen presenting cells.  Our long-term goal is to understand how dysregulation of these events leads to immunodeficiency, autoimmune disease, or cancer.
When a T cell is stimulated by an antigen presenting cell (APC), an actin-rich membrane domain termed the immunological synapse is formed at the cell-cell interface. This event is coordinated by several proteins including WASp, WAVE2, and HS1. Using spinning disk confocal microscopy, we analyze the effects of these actin-regulatory proteins and their upstream regulators on the spatiotemporal control of signaling events at the immunological synapse. T cell-APC engagement also leads to formation of a protein complex distal to the site of TCR engagement, termed the distal pole complex (DPC). The DPC shares many components with the uropod of migrating T cells; both are organized by members of the ERM (ezrin, radixin, moesin) protein family. We are studying the formation of the DPC and uropod, and asking how the proteins that organize these structures direct cell movement both in vitro and in vivo.  Recently, the lab has initiated studies aimed at understanding actin-dependent aspects of dendritic cell function.  Our goal is to define the role of actin-regulatory proteins in dendritic cell migration and antigen presentation. 
Lab expertise and resources:

Widefield and confocal fluorescence microscopy of fixed cells
Spinning disk microscopy of living cells
DIC analysis of cell dynamics and migration
Experience in electron microscopy including cryo-immuno-electron microscopy
Experience in video enhanced DIC analysis of organelle motility
Analysis of T cell signaling pathways
Analysis of cytoskeletal proteins
Analysis of protein trafficking in lymphocytes and dendritic cells

IMIG Collaborations:

Burkhardt and Argon: analysis of HS1 function in antigen presentation by dendritic cells

Burkhardt and Baumgart and Koretzky: use of PALM imaging and patterned surfaces to analyze microcluster dynamics during T cell activation

Burkhardt and Freedman: analysis of the role of actin-regulatory proteins in controlling Ca2+ signaling in lymphocytes

Burkhardt and Hunter: 2-photon imaging of T cell and dendritic cell movement in lymphoid organs

Burkhardt and Koretzky: analysis of spatiotemporal patterning in lymphocytes

Burkhardt, Koretzky and Hammer: Analysis of cytoskeletal anchors and adapter interactions in T cell adhesion and motility

Lab members:

Alex Babich ? Graduate Student

Cytoskeletal control of immunological synapse dynamics

Esteban Carrizosa ? Graduate Student

HS1 function in T cells

Emily Chen ? Graduate Student

Ezrin and moesin function in T cell migration and polarity

Fiona Clarke ? Lab Manager

Dendritic cell cytoskeleton

Ann Huang ? Research Scientist

c-Abl function in T cells

Shuixing Li ? Research Associate

HS1 structure/function

Michael Lipscomb ? Post-doctoral Fellow

c-Abl function in dendritic cells

Research Interests
Regulation of cytoskeletal dynamics in T cells and dendritic cells, and cytoskeletal control of the immune response

Keywords: T cell signaling, dendritic cells, cell migration, antigen presentation, cytoskeletal dynamics, protein traffic, immunodeficiency, autoimmunity, vaccine development, cancer immunotherapy

Research Summary
The focus of my lab is on the role of the cytoskeleton in T cell and dendritic cell function. The cytoskeleton is intimately involved in determining the efficiency and the fidelity of the immune response. For example, when a cytotoxic T cell recognizes a tumor cell for lysis, specific receptor interactions trigger capping of the cortical actin cytoskeleton, creating a specialized membrane domain that is important for T cell signaling events leading to lysis of the tumor cell. Similar processes are important for directing and modulating T cell help. In dendritic cells, actin regulatory proteins control the uptake and presentation of antigens, migration of antigen-bearing cells from sites of infection to lymphoid organs, and defining the outcome of T cell stimulation. Our long-term goals in the lab are to understand how receptor-ligand interactions at the cell surface trigger remodeling of the cytoskeleton, and how the cytoskeleton in turn affects the immune response. Proteins of current interest in the lab include WASP, an actin regulatory protein involved in immunodeficiency disease, HS1, a related protein implicated in autoimmune disease, and Crk family adapter proteins, proteins that control T cell adhesion and migration.

Rotation Projects
Possible rotation projects are always changing. Topics could include analyzing regulation of T cell actin dynamics at the immunological synapse, analyzing actin function during antigen presentation in dendritic cells, or manipulating cytoskeletal signaling pathways to modify T cell migration during T cell immunotherapy.

Lab personnel:
Nathan Roy, Postdoctoral Fellow
Shuixing Li, Research Associate
Edward Williamson, Research Associate
Vidhi Chandra, Research Technician

Ph.D., Microbiology and Immunology, Duke University (1989)
A.B., Biology, Magna Cum Laude, Washington University (1983)
Selected Publications
Shaffer MH, Dupree RS, Zhu P, Saotome I, Schmidt RF, McClatchey AI, Freedman BD, Burkhardt JK.. Ezrin and moesin function together to promote T cell activation.. J Immunol. Vol 182(2) . 2009 Jan:1021-1032..
Huang Y, Comiskey EO, Dupree RS, Li S, Koleske AJ, Burkhardt JK.. The c-Abl tyrosine kinase regulates actin remodeling at the immune synapse. Blood. Vol 112(1) . 2008 Jul:111-119..
Burkhardt, J.K., Carrizosa, E. and Shaffer, M.H.. The actin cytoskeleton in T cell activation.. Ann Rev Immunol. Vol 26, 233-259. 2008 Nov.
Nolz JC, Gomez TS, Zhu P, Li S, Medeiros RB, Shimizu Y, Burkhardt, JK, Freeman BD, Billadeau, DD.. WAVE2 regulates actin cytoskeletal reorganization and CRAC-mediated calcium entry during T cell activation.. Current Biology. Vol 16(1) . 2006 Jan:24-34.
Gomez TS, McCarney SD, Carrizosa E, Labno CM, Comiskey EO, Nolz JC, Zhu P, Freedman BD, Clark MR, Rawlings DJ, Billadeau DD, Burkhardt, JK.. HS1 functions as an essential actin-regulatory adapter protein at the immune synapse.. Immunity. Vol 24(6) . 2006 Jun:741-752.
Gomez TS., Hamann MJ., McCarney S., Savoy DN., Lubking CM., Heldebrant MP., Labno CM., McKean DJ., McNiven MA., Burkhardt JK., Billadeau DD.. Dynamin 2 regulates T cell activation by controlling actin polymerization at the immunological synapse. Nature Immunology. Vol 6(3) . 2005 Mar:261-270.
Labno CM., Lewis CM., You D., Leung DW., Takesono A., Kamberos N., Seth A., Finkelstein LD., Rosen MK., Schwartzberg PL., Burkhardt JK.. Itk functions to control actin polymerization at the immune synapse through localized activation of Cdc42 and WASP. Current Biology. Vol 13(18) . 2003 Sept:1619-1624.
Allenspach EJ, Cullinan P, Tong J, Tang Q, Tesciuba AG, Cannon JL, Takahashi SM, Morgan R, Burkhardt JK, Sperling AI.. ERM-dependent movement of CD43 defines a novel protein complex distal to the immunological synapse.. Immunity. Vol 15(5) . 2001 Nov:739-750.
Cannon JL, Labno CM, Bosco G, Seth A, McGavin MH, Siminovitch KA, Rosen MK, Burkhardt JK.. Wasp recruitment to the T cell:APC contact site occurs independently of Cdc42 activation.. Immunity. Vol 15(2) . 2001 Aug:249-259.
Billadeau, D.D. and Burkhardt, J.K.. Regulation of Cytoskeletal Dynamics at the Immune Synapse: New Stars Join the Actin Troupe. Traffic. Vol 7(11) . 2006 Nov:1451-1460..