JCB logo
Quantitative Colocalization Analysis Software
  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents

Published online 28 January 2002. doi:10.1083/jcb.200108084
This Article
Right arrow Full Text
Right arrow Full Text (PDF, 370K)
Right arrow PPT slides of all figures
Right arrow Alert me when this article is cited
Right arrow Citation Map
Services
Right arrow Email this article
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new content in the JCB
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Dijkers, P. F.
Right arrow Articles by Coffer, P. J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Dijkers, P. F.
Right arrow Articles by Coffer, P. J.
Social Bookmarking
 Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati  
What's this?

© The Rockefeller University Press, 0021-9525/2002/2/531 $5.00
The Journal of Cell Biology, Volume 156, Number 3, February 4, 2002 531-542


Article

FKHR-L1 can act as a critical effector of cell death induced by cytokine withdrawal

: protein kinase B–enhanced cell survival through maintenance of mitochondrial integrity



Pascale F. Dijkers1, Kim U. Birkenkamp1, Eric W.-F. Lam2, N. Shaun B. Thomas3, Jan-Willem J. Lammers1, Leo Koenderman1 and Paul J. Coffer1

1 Department of Pulmonary Diseases, University Medical Center, 3584 CX Utrecht, Netherlands
2 CRC Labs and Section of Cancer Cell Biology, Imperial College School of Medicine at Hammersmith Hospital, London W12 ONN, UK
3 Guy's, King's, St. Thomas's School of Medicine and Dentistry, The Rayne Institute, London SE5 9NU, UK

Address correspondence to Paul J. Coffer, Department of Pulmonary Diseases, G03.550, University Medical Center, Heidelberglaan 100, 3584 CX Utrecht, Netherlands. Tel.: 31-30-250-7134. Fax: 31-30-250-5414. E-mail: p.coffer{at}hli.azu.nl

Survival signals elicited by cytokines include the activation of phosphatidylinositol 3-kinase (PI3K), which in turn promotes the activation of protein kinase B (PKB). Recently, PKB has been demonstrated to phosphorylate and inactivate forkhead transcription factor FKHR-L1, a potent inducer of apoptosis. To explore the mechanisms underlying the induction of apoptosis after cytokine withdrawal or FKHR-L1 activation, we used a cell line in which FKHR-L1 activity could be specifically induced. Both cytokine withdrawal and FKHR-L1 activation induced apoptosis, which was preceded by an upregulation in p27KIP1 and a concomitant decrease in cells entering the cell cycle. Induction of apoptosis by both cytokine withdrawal and activation of FKHR-L1 correlated with the disruption of mitochondrial membrane integrity and cytochrome c release. This was preceded by upregulation of the pro-apoptotic Bcl-2 family member Bim. Ectopic expression of an inhibitory mutant of FKHR-L1 substantially reduced the levels of apoptosis observed after cytokine withdrawal. Activation of PKB alone was sufficient to promote cell survival, as measured by maintenance of mitochondrial integrity and the resultant inhibition of effector caspases. Furthermore, hematopoietic stem cells isolated from Bim-/- mice exhibited reduced levels of apoptosis upon inhibition of PI3K/PKB signaling.

These data demonstrate that activation of FKHR-L1 alone can recapitulate all known elements of the apoptotic program normally induced by cytokine withdrawal. Thus PI3K/PKB–mediated inhibition of this transcription factor likely provides an important mechanism by which survival factors act to prevent programmed cell death.

Key Words: apoptosis; cytokine; mitochondria; PI3K; forkhead


Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Reddit Reddit   Add to Technorati Technorati    What's this?


This article has been cited by other articles:



  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents