T-cell ubiquitin ligand affects cell death through a functional interaction with apoptosis-inducing factor, a key factor of caspase-independent apoptosis.
The lymphoid protein T-cell ubiquitin ligand (TULA)/suppressor of T-cell receptor signaling (Sts)-2 is associated with c-Cbl and ubiquitylated proteins and has been implicated in the regulation of signaling mediated by protein-tyrosine kinases. The results presented in this report indicate that TULA facilitates T-cell apoptosis independent of either T-cell receptor/CD3-mediated signaling or caspase activity. Mass spectrometry-based analysis of protein-protein interactions of TULA demonstrates that TULA binds to the apoptosis-inducing protein AIF, which has previously been shown to function as a key factor of caspase-independent apoptosis. Using RNA interference, we demonstrate that AIF is essential for the apoptotic effect of TULA. Analysis of the subcellular localization of TULA and AIF together with the functional analysis of TULA mutants is consistent with the idea that TULA enhances the apoptotic effect of AIF by facilitating the interactions of AIF with its apoptotic co-factors, which remain to be identified. Overall, our results shed new light on the biological functions of TULA, a recently discovered protein, describing its role as one of very few known functional interactors of AIF.
Collingwood
Therese S
TS
Department of Microbiology and Immunology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA.
Smirnova
Evgeniya V
EV
Bogush
Marina
M
Carpino
Nick
N
Annan
Roland S
RS
Tsygankov
Alexander Y
AY
D017209:Apoptosis / Q000502:physiology*; D051033:Apoptosis Inducing Factor / Q000235:genetics / Q000378:metabolism*; D017252:CD3 Complex / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D020169:Caspases / Q000235:genetics / Q000378:metabolism*; D016923:Cell Death / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D019169:Jurkat Cells; D013058:Mass Spectrometry; D008565:Membrane Proteins; D009154:Mutation; D011485:Protein Binding; D050721:Proto-Oncogene Proteins c-cbl / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D054875:Ubiquitination / Q000502:physiology*; D014452:Ubiquitins / Q000235:genetics / Q000378:metabolism
C494829:AIFM1 protein, human; D051033:Apoptosis Inducing Factor; D017252:CD3 Complex; C489394:CLIP4 protein, human; D002352:Carrier Proteins; D008565:Membrane Proteins; D011948:Receptors, Antigen, T-Cell; D014452:Ubiquitins; D050721:Proto-Oncogene Proteins c-cbl; D020169:Caspases; C067419:CBL protein, human