Type

Journal Article

Authors

M Rehm
J H M Prehn
M Devocelle
A Lichawska
A Spring
L P Tuffy
J SebastiĆ 
L Flanagan

Subjects

Biochemistry

Topics
mitochondria mitochondrial proteins humans pharmacology metabolism animals cytochromes c luminescent proteins cell membrane permeability recombinant fusion proteins digitonin x linked inhibitor of apoptosis protein diablo protein mouse genetics apoptosis carrier proteins cell proliferation neurons mice cells cultured

XIAP impairs Smac release from the mitochondria during apoptosis. (2010)

Abstract X-linked inhibitor of apoptosis protein (XIAP) is a potent inhibitor of caspases 3, 7 and 9, and mitochondrial Smac (second mitochondria-derived activator of caspase) release during apoptosis inhibits the activity of XIAP. In this study we show that cytosolic XIAP also feeds back to mitochondria to impair Smac release. We constructed a fluorescent XIAP-fusion protein by labelling NH(2)- and COOH-termini with Cerulean fluorescent protein (C-XIAP-C). Immunoprecipitation confirmed that C-XIAP-C retained the ability to interact with Smac and impaired extrinsically and intrinsically activated apoptosis in response to tumour necrosis factor-related apoptosis-inducing ligand/cycloheximide and staurosporine. In C-XIAP-C-expressing cells, cytochrome c release from mitochondria proceeded normally, whereas Smac release was significantly prolonged and incomplete. In addition, physiological expression of native XIAP prolonged or limited Smac release in HCT-116 colon cancer cells and primary mouse cortical neurons. The Smac-binding capacity of XIAP, but not caspase inhibition, was central for mitochondrial Smac retention, as evidenced in experiments using XIAP mutants that cannot bind to Smac or effector caspases. Similarly, the release of a Smac mutant that cannot bind to XIAP was not impaired by C-XIAP-C expression. Full Smac release could however be provoked by rapid cytosolic C-XIAP-C depletion upon digitonin-induced plasma membrane permeabilization. Our findings suggest that although mitochondria may already contain pores sufficient for cytochrome c release, elevated amounts of XIAP can selectively impair and limit the release of Smac.
Collections Ireland -> Royal College of Surgeons in Ireland -> PubMed

Full list of authors on original publication

M Rehm, J H M Prehn, M Devocelle, A Lichawska, A Spring, L P Tuffy, J SebastiĆ , L Flanagan

Experts in our system

1
Markus Rehm
Royal College of Surgeons in Ireland
Total Publications: 55
 
2
Jochen H M Prehn
Royal College of Surgeons in Ireland
Total Publications: 206
 
3
Marc Devocelle
Royal College of Surgeons in Ireland
Total Publications: 65
 
4
Liam P Tuffy
Royal College of Surgeons in Ireland
Total Publications: 13
 
5
Lorna Flanagan
Royal College of Surgeons in Ireland
Total Publications: 23