15 research outputs found
Inactivation of Effector Caspases through Nondegradative Polyubiquitylation
Ubiquitin-mediated inactivation of caspases has long been postulated to contribute to the regulation of apoptosis. However, detailed mechanisms and functional consequences of caspase ubiquitylation have not been demonstrated. Here we show that the Drosophila Inhibitor of Apoptosis 1, DIAP1, blocks effector caspases by targeting them for polyubiquitylation and nonproteasomal inactivation. We demonstrate that the conjugation of ubiquitin to drICE suppresses its catalytic potential in cleaving caspase substrates. Our data suggest that ubiquitin conjugation sterically interferes with substrate entry and reduces the caspaseâs proteolytic velocity. Disruption of drICE ubiquitylation, either by mutation of DIAP1âs E3 activity or drICEâs ubiquitin-acceptor lysines, abrogates DIAP1âs ability to neutralize drICE and suppress apoptosis in vivo. We also show that DIAP1 rests in an âinactiveâ conformation that requires caspase-mediated cleavage to subsequently ubiquitylate caspases. Taken together, our findings demonstrate that effector caspases regulate their own inhibition through a negative feedback mechanism involving DIAP1 âactivationâ and nondegradative polyubiquitylation
Differential comparison of EGFR/HER2-dependent signaling dynamics in breast cancer cell lines by quantitative mass spectrometry
<strong>Characterization of ubiquitination dependent dynamics in growth factor receptorsignaling by quantitative proteomics</strong>
Phosphoproteomic profiling reveals a defined genetic program for osteoblastic lineage commitment of human bone marrow-derived stromal stem cells
Metabolic and hepatic effects of liraglutide, obeticholic acid and elafibranor in diet-induced obese mouse models of biopsy-confirmed nonalcoholic steatohepatitis
Phosphoproteomic profiling reveals a defined genetic program for osteoblastic lineage commitment of human bone marrowâderived stromal stem cells
Bone marrowâderived mesenchymal stem cells (MSCs) differentiate into osteoblasts upon stimulation by signals present in their niche. Because the global signaling cascades involved in the early phases of MSCs osteoblast (OB) differentiation are not well-defined, we used quantitative mass spectrometry to delineate changes in human MSCs proteome and phosphoproteome during the first 24 h of their OB lineage commitment. The temporal profiles of 6252 proteins and 15,059 phosphorylation sites suggested at least two distinct signaling waves: one peaking within 30 to 60 min after stimulation and a second upsurge after 24 h. In addition to providing a comprehensive view of the proteome and phosphoproteome dynamics during early MSCs differentiation, our analyses identified a key role of serine/threonine protein kinase D1 (PRKD1) in OB commitment. At the onset of OB differentiation, PRKD1 initiates activation of the pro-osteogenic transcription factor RUNX2 by triggering phosphorylation and nuclear exclusion of the histone deacetylase HDAC7