Functional identification of kinases essential for T-cell activation through a genetic suppression screen.
Activation of T-cells by antigens initiates a complex series of signal-transduction events that are critical for immune responses. While kinases are key mediators of signal transduction networks, several of which have been well characterized in T-cell activation, the functional roles of other kinases remain poorly defined. To address this deficiency, we developed a genetic screen to survey the functional roles of kinases in antigen mediated T-cell activation. A retroviral library was constructed that expressed genetic suppressor elements (GSEs) comprised of peptides and antisense nucleotides derived from kinase cDNAs including members of the STE, CAMK, AGC, CMGC, RGC, TK, TKL, Atypical, and Lipid kinase groups. The retroviral library was expressed in Jurkat T-cells and analyzed for their effect on T-cell activation as monitored by CD69 expression. Jurkat cells were activated by antigen presenting cells treated with superantigen, and sorted for a CD69 negative phenotype by flow cytometry. We identified 19 protein kinases that were previously implicated in T-cell signaling processes and 12 kinases that were not previously linked to T-cell activation. To further validate our approach, we characterized the role of the protein kinase MAP4K4 that was identified in the screen. siRNA studies showed a role for MAP4K4 in antigen mediated T-cell responses in Jurkat and primary T-cells. In addition, by analyzing multiple promoter elements using reporter assays, we have shown that MAP4K4 is implicated in the activation of the TNF-alpha promoter. Our results suggest that this methodology could be used to survey the function of the entire kinome in T-cell activation.
Mack
Karl D
KD
PPD Discovery Inc., 1505 O'Brien Drive, Menlo Park, CA 94025, USA. xkmack@hotmail.com
Von Goetz
Melissa
M
Lin
Monica
M
Venegas
Marina
M
Barnhart
Jerry
J
Lu
Yan
Y
Lamar
Betty
B
Stull
Robert
R
Silvin
Christopher
C
Owings
Pamela
P
Bih
Fong-Yih
FY
Abo
Arie
A
D015703:Antigens, CD / Q000276:immunology / Q000378:metabolism; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology / Q000378:metabolism; D005822:Genetic Vectors; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D019169:Jurkat Cells; D037181:Lectins, C-Type; D008213:Lymphocyte Activation / Q000235:genetics / Q000276:immunology*; D019151:Peptide Library; D010770:Phosphotransferases / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012190:Retroviridae; D013601:T-Lymphocytes / Q000201:enzymology* / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics; D000099192:CD69 Antigens
D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D047908:Intracellular Signaling Peptides and Proteins; D037181:Lectins, C-Type; D019151:Peptide Library; D010770:Phosphotransferases; D017346:Protein Serine-Threonine Kinases; D014409:Tumor Necrosis Factor-alpha; D000099192:CD69 Antigens; C117090:MAP4K4 protein, human