The anti-apoptotic function of Hsp70 in the interferon-inducible double-stranded RNA-dependent protein kinase-mediated death signaling pathway requires the Fanconi anemia protein, FANCC.
Proteins encoded by five of the six known Fanconi anemia (FA) genes form a heteromeric complex that facilitates repair of DNA damage induced by cross-linking agents. A certain number of these proteins, notably FANCC, also function independently to modulate apoptotic signaling, at least in part, by suppressing ground state activation of the pro-apoptotic interferon-inducible double-stranded RNA-dependent protein kinase (PKR). Because certain FANCC mutations interdict its anti-apoptotic function without interfering with the capacity of FANCC to participate functionally in the FA multimeric complex, we suspected that FANCC enhances cell survival independent of its participation in the complex. By investigating this function in both mammalian cells and in yeast, an organism with no FA orthologs, we show that FANCC inhibited the kinase activity of PKR both in vivo and in vitro, and this effect depended upon a physical interaction between FANCC and Hsp70 but not on interactions of FANCC with other Fanconi proteins. Hsp70, FANCC, and PKR form a ternary complex in lymphoblasts and in yeast expressing PKR. We conclude that Hsp70 requires the cooperation of FANCC to suppress PKR activity and support survival of hematopoietic cells and that FANCC does not require the multimeric FA complex to exert this function.
Pang
Qishen
Q
OHSU Cancer Institute, Department of Medicine and Molecular and Medical Genetics, Oregon Health and Science University, Portland, OR 97201, USA.
Christianson
Tracy A
TA
Keeble
Winifred
W
Koretsky
Tara
T
Bagby
Grover C
GC
D017209:Apoptosis; D018797:Cell Cycle Proteins; D016923:Cell Death; D002460:Cell Line; D004249:DNA Damage; D004268:DNA-Binding Proteins; D004789:Enzyme Activation; D052218:Fanconi Anemia Complementation Group C Protein; D051856:Fanconi Anemia Complementation Group Proteins; D005982:Glutathione Transferase / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism* / Q000494:pharmacology*; D006412:Hematopoietic Stem Cells / Q000502:physiology; D006801:Humans; D015151:Immunoblotting; D007371:Interferon-gamma / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation; D009687:Nuclear Proteins; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism / Q000502:physiology*; D012330:RNA, Double-Stranded / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D015398:Signal Transduction; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D019892:eIF-2 Kinase / Q000037:antagonists & inhibitors* / Q000378:metabolism*
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C497651:FANCC protein, human; D052218:Fanconi Anemia Complementation Group C Protein; D051856:Fanconi Anemia Complementation Group Proteins; D018840:HSP70 Heat-Shock Proteins; D009687:Nuclear Proteins; D011506:Proteins; D012330:RNA, Double-Stranded; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D005982:Glutathione Transferase; D019892:eIF-2 Kinase