A Fas-associated death domain protein/caspase-8-signaling axis promotes S-phase entry and maintains S6 kinase activity in T cells responding to IL-2.

Published

Journal Article

Fas-associated death domain protein (FADD) constitutes an essential component of TNFR-induced apoptotic signaling. Paradoxically, FADD has also been shown to be crucial for lymphocyte development and activation. In this study, we report that FADD is necessary for long-term maintenance of S6 kinase (S6K) activity. S6 phosphorylation at serines 240 and 244 was only observed after long-term stimulation of wild-type cells, roughly corresponding to the time before S-phase entry, and was poorly induced in T cells expressing a dominantly interfering form of FADD (FADDdd), viral FLIP, or possessing a deficiency in caspase-8. Defects in S6K1 phosphorylation were also observed. However, defective S6K1 phosphorylation was not a consequence of a wholesale defect in mammalian target of rapamycin function, because 4E-BP1 phosphorylation following T cell activation was unaffected by FADDdd expression. Although cyclin D3 up-regulation and retinoblastoma hypophosphorylation occurred normally in FADDdd T cells, cyclin E expression and cyclin-dependent kinase 2 activation were markedly impaired in FADDdd T cells. These results demonstrate that a FADD/caspase-8-signaling axis promotes T cell cycle progression and sustained S6K activity.

Full Text

Duke Authors

Cited Authors

  • Arechiga, AF; Bell, BD; Leverrier, S; Weist, BM; Porter, M; Wu, Z; Kanno, Y; Ramos, SJ; Ong, ST; Siegel, R; Walsh, CM

Published Date

  • October 15, 2007

Published In

Volume / Issue

  • 179 / 8

Start / End Page

  • 5291 - 5300

PubMed ID

  • 17911615

Pubmed Central ID

  • 17911615

International Standard Serial Number (ISSN)

  • 0022-1767

Digital Object Identifier (DOI)

  • 10.4049/jimmunol.179.8.5291

Language

  • eng

Conference Location

  • United States