Showing papers by "Sally Kornbluth published in 2009"
Institut Gustave Roussy1, French Institute of Health and Medical Research2, University of Paris-Sud3, Icahn School of Medicine at Mount Sinai4, University of Texas Southwestern Medical Center5, Thomas Jefferson University6, McMaster University7, University of Massachusetts Medical School8, LSU Health Sciences Center New Orleans9, Roswell Park Cancer Institute10, Boston Children's Hospital11, University of Gothenburg12, University of Freiburg13, University of California, San Francisco14, Buck Institute for Research on Aging15, Centre national de la recherche scientifique16, National Institutes of Health17, Technion – Israel Institute of Technology18, University of Leicester19, University of Chieti-Pescara20, Istituto Superiore di Sanità21, University of North Carolina at Chapel Hill22, New York University23, University of Pennsylvania24, Howard Hughes Medical Institute25, Yale University26, University of Ulm27, University of Burgundy28, Aix-Marseille University29, Pasteur Institute30, University of Strasbourg31, Johns Hopkins University32, University of Zurich33, University of Tokyo34, Weizmann Institute of Science35, University of Michigan36, University College London37, Duke University38, University of Graz39, Ghent University40, Trinity College, Dublin41, University of Amsterdam42, University of Lyon43, University of Rome Tor Vergata44, Stony Brook University45, University of Göttingen46, Kyoto University47, Merck & Co.48, Austrian Academy of Sciences49, National University of Singapore50, University of Chicago51, Royal College of Surgeons in Ireland52, La Trobe University53, University of Buenos Aires54, University of Padua55, University of Lisbon56, University of Cambridge57, University of Würzburg58, University of Geneva59, University of Bern60, Rockefeller University61, University of Lausanne62, Osaka University63, University of California, San Diego64, University of Glasgow65, Harvard University66, Karolinska Institutet67
TL;DR: A nonexhaustive comparison of methods to detect cell death with apoptotic or nonapoptotic morphologies, their advantages and pitfalls is provided and the importance of performing multiple, methodologically unrelated assays to quantify dying and dead cells is emphasized.
Abstract: Cell death is essential for a plethora of physiological processes, and its deregulation characterizes numerous human diseases Thus, the in-depth investigation of cell death and its mechanisms constitutes a formidable challenge for fundamental and applied biomedical research, and has tremendous implications for the development of novel therapeutic strategies It is, therefore, of utmost importance to standardize the experimental procedures that identify dying and dead cells in cell cultures and/or in tissues, from model organisms and/or humans, in healthy and/or pathological scenarios Thus far, dozens of methods have been proposed to quantify cell death-related parameters However, no guidelines exist regarding their use and interpretation, and nobody has thoroughly annotated the experimental settings for which each of these techniques is most appropriate Here, we provide a nonexhaustive comparison of methods to detect cell death with apoptotic or nonapoptotic morphologies, their advantages and pitfalls These guidelines are intended for investigators who study cell death, as well as for reviewers who need to constructively critique scientific reports that deal with cellular demise Given the difficulties in determining the exact number of cells that have passed the point-of-no-return of the signaling cascades leading to cell death, we emphasize the importance of performing multiple, methodologically unrelated assays to quantify dying and dead cells
2,218 citations
TL;DR: How the balance between cell survival and cell death can be shifted through crosstalk between these two enzyme families is discussed.
446 citations
TL;DR: It is reported here that protein phosphatase-1 (PP1) is the main catalyst of mitotic phosphoprotein dephosphorylation, and Cdc2 both phosphorylates multiple mitotic substrates and inhibits their PP1-mediated deph phosphorylation.
Abstract: Mitotic exit occurs when Cdc2 kinase activity drops and its substrates are dephosphorylated. Protein phosphatase-1 is responsible for this dephosphorylation and its activity is restrained during mitosis by Cdc2 phosphorylation and binding of Inhibitor-1, while auto-dephoshorylation at the Cdc2 site ensures its timely activation.
239 citations
TL;DR: For apoptotic stimuli transduced by caspase‐2, cell death is prevented during mitosis through the inhibitory phosphorylation of caspases2 and it is suggested that under conditions of mitotic arrest, cdk1–cyclin B1 activity must be overcome for apoptosis to occur.
Abstract: The apoptotic initiator caspase-2 has been implicated in oocyte death, in DNA damage- and heat shock-induced death, and in mitotic catastrophe. We show here that the mitosis-promoting kinase, cdk1–cyclin B1, suppresses apoptosis upstream of mitochondrial cytochrome c release by phosphorylating caspase-2 within an evolutionarily conserved sequence at Ser 340. Phosphorylation of this residue, situated in the caspase-2 interdomain, prevents caspase-2 activation. S340 was susceptible to phosphatase 1 dephosphorylation, and an interaction between phosphatase 1 and caspase-2 detected during interphase was lost in mitosis. Expression of S340A non-phosphorylatable caspase-2 abrogated mitotic suppression of caspase-2 and apoptosis in various settings, including oocytes induced to undergo cdk1-dependent maturation. Moreover, U2OS cells treated with nocodazole were found to undergo mitotic catastrophe more readily when endogenous caspase-2 was replaced with the S340A mutant to lift mitotic inhibition. These data demonstrate that for apoptotic stimuli transduced by caspase-2, cell death is prevented during mitosis through the inhibitory phosphorylation of caspase-2 and suggest that under conditions of mitotic arrest, cdk1–cyclin B1 activity must be overcome for apoptosis to occur.
113 citations
TL;DR: It is shown that C2 phosphorylated at S135 binds 14-3-3zeta, thus preventing C2 dephosphorylation, and similar control of murine C2 by phosphorylation and 14- 3-3 binding in mouse eggs is demonstrated.
95 citations
TL;DR: It is reported here that in cells recovering from hydroxyurea (HU)-induced genotoxic stress, RPA32 is dephosphorylated by the serine/threonine protein phosphatase 2A (PP2A) and this data indicate that PP2A-mediated R PA32 deph phosphorylation is required for the efficient DNA damage repair.
Abstract: Eukaryotic genomic integrity is safeguarded by cell cycle checkpoints and DNA repair pathways, collectively known as the DNA damage response, wherein replication protein A (RPA) is a key regulator playing multiple critical roles. The genotoxic insult-induced phosphorylation of the 32-kDa subunit of human RPA (RPA32), most notably the ATM/ATR-dependent phosphorylation at T21 and S33, acts to suppress DNA replication and recruit other checkpoint/repair proteins to the DNA lesions. It is not clear, however, how the DNA damage-responsive function of phosphorylated RPA is attenuated and how the replication-associated activity of the unphosphorylated form of RPA is restored when cells start to resume the normal cell cycle. We report here that in cells recovering from hydroxyurea (HU)-induced genotoxic stress, RPA32 is dephosphorylated by the serine/threonine protein phosphatase 2A (PP2A). Interference with PP2A catalytic activity causes persistent RPA32 phosphorylation and increased HU sensitivity. The PP2A catalytic subunit binds to RPA following DNA damage and can dephosphorylate RPA32 in vitro. Cells expressing a RPA32 persistent phosphorylation mimetic exhibit normal checkpoint activation and reenter the cell cycle normally after recovery but display a pronounced defect in the repair of DNA breaks. These data indicate that PP2A-mediated RPA32 dephosphorylation is required for the efficient DNA damage repair.
65 citations
TL;DR: The results indicate that the C-terminal PDZ-binding motif of Glut1 plays a key role in growth factor regulation of glucose uptake by both allowing GIPC to promote GlUT1 trafficking to the cell surface and protecting intracellular Glut 1 from lysosomal degradation after growth factor withdrawal, thus allowing the potential for a rapid return of intrace cellular Glut2 to thecell surface on restimulation.
Abstract: Cell surface localization of the glucose transporter, Glut1, is a cytokine-controlled process essential to support the metabolism and survival of hematopoietic cells. Molecular mechanisms that regulate Glut1 trafficking, however, are not certain. Here we show a C-terminal PDZ-binding motif in Glut1 is critical to promote maximal cytokine-stimulated Glut1 cell surface localization and prevent Glut1 lysosomal degradation in the absence of growth factor. Disruption of this PDZ-binding sequence through deletion or point mutation sharply decreased surface Glut1 levels and led to rapid targeting of internalized Glut1 to lysosomes for proteolysis, particularly in growth factor-deprived cells. The PDZ domain protein, GIPC, bound to Glut1 in part via the Glut1 C-terminal PDZ binding motif and we found that GIPC-deficiency decreased Glut1 surface levels and glucose uptake. Unlike the Glut1 degradation observed upon mutation of the Glut1 PDZ-binding domain, however, GIPC-deficiency resulted in accumulation of intracellular Glut1 in a pool distinct from the recycling pathway of the Transferrin Receptor (TfR). Blockade of Glut1 lysosomal targeting after growth factor withdrawal also led to intracellular accumulation of Glut1, a portion of which could be rapidly restored to the cell surface after growth factor stimulation. These data indicate that the C-terminal PDZ-binding motif of Glut1 plays a key role in growth factor regulation of glucose uptake by both allowing GIPC to promote Glut1 trafficking to the cell surface and protecting intracellular Glut1 from lysosomal degradation after growth factor withdrawal, thus allowing potential for a rapid return of intracellular Glut1 to the cell surface upon re-stimulation.
51 citations
15 Dec 2009
TL;DR: The cellular morphological changes associated with apoptosis encompass three stages: release, membrane blebbing and condensation, which results in dramatic morphological and biochemical changes in the dying cell due to the systematic dismantling of cellular architecture and functional pathways.
Abstract: Apoptosis is a programme of cell death that results in dramatic morphological and biochemical changes in the dying cell due to the systematic dismantling of cellular architecture and functional pathways. The proteins that execute the apoptotic programme are a group of proteases termed caspases (cysteine-dependent aspartate-specific protease). Caspases proteolytically cleave a host of cellular substrates at aspartate residues, which may render them either functionally inactive or confer novel activities that help to promote cellular demise. Substrates targeted by caspases during the apoptotic programme include proteins involved in maintaining various aspects of cytoskeletal and organelle architecture as well as proteins that function in signalling networks critical for cell function. Following the execution phase of apoptosis, the cellular corpse is packaged in an orderly fashion into membrane-bound apoptotic bodies that are sensed by phagocytes, which neatly engulf the dead cell without eliciting an immune response.
Key concepts:
Apoptotic caspases are cysteine proteases which become activated in response to diverse extracellular and intracellular stimuli and subsequently carry out the cell death programme by systematically cleaving intracellular proteins.
A hierarchy of caspase activation exists whereby initiator caspases become activated to cleave and activate effector caspases, which then dismantle the cell through proteolytical cleavage of intracellular.
The cellular morphological changes associated with apoptosis encompass three stages: release, membrane blebbing and condensation.
Caspase-mediated cleavage of target proteins may produce stable functional effector fragments or unstable fragments that are quickly degraded.
Caspases target multiple aspects of the cellular architecture to induce collapse of organelles and the cytoskeleton.
Signalling networks that regulate cellular processes critical for cell survival are inactivated by caspases.
As the dying cell is dismantled during the apoptotic process, it orchestrates its own disposal by displaying ‘eat me’ signals on its cell surface and releasing ‘find me’ signals to recruit phagocytic cells.
Keywords:
initiator caspase;
effector caspase;
membrane blebbing;
nuclear disintegration;
cellular condensation;
apoptotic bodies
2 citations
TL;DR: A novel approach to visualizing caspase-2 activation in real time is developed, enabling resolution of several controversies surrounding the position of this enzyme in apoptotic signaling cascades.
1 citations