Defective nuclear translocation of nuclear factor of activated T cells and extracellular signal-regulated kinase underlies deficient IL-2 gene expression in Wiskott-Aldrich syndrome.
BACKGROUND
Proliferation and IL-2 production in response to T-cell receptor ligation are impaired in patients with Wiskott-Aldrich syndrome (WAS). The transcription factors nuclear factor-kappaB (NF-kappaB), nuclear factor of activated T cells (NF-AT), and activating protein-1 (AP-1) play a critical role in IL-2 gene expression.


OBJECTIVE
To investigate the mechanisms of impaired IL-2 production after T-cell receptor ligation in T cells deficient in WAS protein (WASP).


METHODS
T cells from WASP-/- mice were stimulated with anti-CD3 and anti-CD28. Nuclear NF-kappaB, NF-AT, and AP-1 DNA-binding activity was examined by electroshift mobility assay. NF-ATp dephosphorylation and nuclear localization were examined by Western blot and indirect immunofluorescence. Phosphorylation of the mitogen-activated protein kinases Erk and Jnk, and of their nuclear substrates Elk-1 and c-Jun, was examined by Western blot. Expression of mRNA for IL-2 and the NF-kappaB-dependent gene A20 and of the AP-1 components c-fos and c-Jun was examined by quantitative RT-PCR.


RESULTS
Nuclear translocation and activity of NF-kappaB were normal in T cells from WASP-/- mice. In contrast, NF-ATp dephosphorylation and nuclear localization, nuclear AP-1 binding activity, and expression of c-fos, but not c-Jun, were all impaired. Phosphorylation of Jnk, c-Jun, and Erk were normal. However, nuclear translocation of phosphorylated Erk and phosphorylation of its nuclear substrate Elk1, which activates the c-fos promoter, were impaired.


CONCLUSIONS
These results suggest that WASP is essential for NF-ATp activation, and for nuclear translocation of p-Erk, Elk1 phosphorylation, and c-fos gene expression in T cells. These defects underlie defective IL-2 expression and T-cell proliferation in WAS.
Cianferoni
Antonella
A
Division of Immunology, Children's Hospital, Boston, MA 02115, USA.
Massaad
Michel
M
Feske
Stefan
S
de la Fuente
Miguel A
MA
Gallego
Lola
L
Ramesh
Narayanaswamy
N
Geha
Raif S
RS
D021581:Active Transport, Cell Nucleus; D000818:Animals; D004247:DNA / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D007376:Interleukin-2 / Q000235:genetics*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D050778:NFATC Transcription Factors / Q000378:metabolism*; D010766:Phosphorylation; D021381:Protein Transport; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D013601:T-Lymphocytes / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014923:Wiskott-Aldrich Syndrome / Q000378:metabolism*; D051316:Wiskott-Aldrich Syndrome Protein / Q000502:physiology*
D007376:Interleukin-2; D016328:NF-kappa B; D050778:NFATC Transcription Factors; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; C495768:Was protein, mouse; D051316:Wiskott-Aldrich Syndrome Protein; D004247:DNA; D048049:Extracellular Signal-Regulated MAP Kinases