Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Donald W. Nicholson is active.

Publication


Featured researches published by Donald W. Nicholson.


Biochimica et Biophysica Acta | 1989

Mitochondrial protein import

Franz-Ulrich Hartl; Nikolaus Pfanner; Donald W. Nicholson; Walter Neupert

The transport of nuclear-encoded proteins from the cytosol into mitochondria is mediated by targeting (signal) sequences present on precursor forms. Most precursors of the mitochondrial matrix possess amino-terminal signals which characteristically contain hydroxylated and basic amino acids and lack acidic residues. With a minority of precursor proteins, internal sequence motifs can direct proteins to the mitochondria (Pfanner, N., Hoeben, P., Tropschug, M. and Neupert, W. (1987) J. Biol. Chem. 262, 14851–14854). The presence of a mitochondrial targeting sequence alone, however, is not sufficient for specific targeting to the organelle and further to the various subcompartments. There is the need for components which recognise the targeting sequences and others which keep the precursor protein in a translocation-competent form. Beyond the recognition step, components are required which mediate translocation across the mitochondrial membranes. Mitochondria possess two translocation machineries, one in the outer membrane and one in the inner membrane. The matrix space harbors a number of factors which participate in the import of proteins, in their unfolding and folding. Energy is required at several steps of these processes.


Proceedings of the National Academy of Sciences of the United States of America | 2001

Maintenance of caspase-3 proenzyme dormancy by an intrinsic “safety catch” regulatory tripeptide

Sophie Roy; Christopher I. Bayly; Yves Gareau; Vicky M. Houtzager; Stacia Kargman; Sabina L. C. Keen; Kathleen Rowland; Isolde M. Seiden; Nancy A. Thornberry; Donald W. Nicholson

Caspase-3 is synthesized as a dormant proenzyme and is maintained in an inactive conformation by an Asp-Asp-Asp “safety-catch” regulatory tripeptide contained within a flexible loop near the large-subunit/small-subunit junction. Removal of this “safety catch” results in substantially enhanced autocatalytic maturation as well as increased vulnerability to proteolytic activation by upstream proteases in the apoptotic pathway such as caspase-9 and granzyme B. The safety catch functions through multiple ionic interactions that are disrupted by acidification, which occurs in the cytosol of cells during the early stages of apoptosis. We propose that the caspase-3 safety catch is a key regulatory checkpoint in the apoptotic cascade that regulates terminal events in the caspase cascade by modulating the triggering of caspase-3 activation.


Proceedings of the National Academy of Sciences of the United States of America | 2009

Gender differences in expression of the human caspase-12 long variant determines susceptibility to Listeria monocytogenes infection

Garabet Yeretssian; Karine Doiron; Wei Shao; Blair R. Leavitt; Michael R. Hayden; Donald W. Nicholson; Maya Saleh

Inflammatory caspases are important effectors of innate immunity. Caspase-12, of the inflammatory caspase subfamily, is expressed in all mammals tested to date, but has acquired deleterious mutation in humans. A single-nucleotide polymorphism introduces a premature stop codon in caspase-12 in the majority of the population. However, in 20% of African descendants, caspase-12 is expressed and sensitizes to infections and sepsis. Here, we examined the modalities by which human caspase-12 confers susceptibility to infection. We have generated a fully humanized mouse that expresses the human caspase-12 rare variant (Csp-12L) in a mouse casp-12−/− background. Characterization of the humanized mouse uncovered sex differences in Csp-12L expression and gender disparity in innate immunity to Listeria monocytogenes infection. The Csp-12L transgene completely reversed the knockout resistance-to-infection phenotype in casp-12−/− males. In contrast, it had a marginal effect on the response of female mice. We found that estrogen levels modulated the expression of caspase-12. Csp-12L was expressed in male mice but its expression was repressed in female mice. Administration of 17-β-estradiol (E2) to humanized male mice had a direct suppressive effect on Csp-12L expression and conferred relative resistance to infection. Chromatin immunoprecipitation experiments revealed that caspase-12 is a direct transcriptional target of the estrogen receptor alpha (ERα) and mapped the estrogen response element (ERE) to intron 7 of the gene. We propose that estrogen-mediated inhibition of Csp-12L expression is a built-in mechanism that has evolved to protect females from infection.


Journal of Experimental Medicine | 2004

Differential efficacy of caspase inhibitors on apoptosis markers during sepsis in rats and implication for fractional inhibition requirements for therapeutics

Nathalie Méthot; JingQi Huang; Nathalie Coulombe; John P. Vaillancourt; Dita M. Rasper; John Tam; Yongxin Han; John Colucci; Robert Zamboni; Steven Xanthoudakis; Sylvie Toulmond; Donald W. Nicholson; Sophie Roy

A rodent model of sepsis was used to establish the relationship between caspase inhibition and inhibition of apoptotic cell death in vivo. In this model, thymocyte cell death was blocked by Bcl-2 transgene, indicating that apoptosis was predominantly dependent on the mitochondrial pathway that culminates in caspase-3 activation. Caspase inhibitors, including the selective caspase-3 inhibitor M867, were able to block apoptotic manifestations both in vitro and in vivo but with strikingly different efficacy for different cell death markers. Inhibition of DNA fragmentation required substantially higher levels of caspase-3 attenuation than that required for blockade of other apoptotic events such as spectrin proteolysis and phosphatidylserine externalization. These data indicate a direct relationship between caspase inhibition and some apoptotic manifestations but that small quantities of uninhibited caspase-3 suffice to initiate genomic DNA breakdown, presumably through the escape of catalytic quantities of caspase-activated DNase. These findings suggest that putative caspase-independent apoptosis may be overestimated in some systems since blockade of spectrin proteolysis and other cell death markers does not accurately reflect the high degrees of caspase-3 inhibition needed to prevent DNA fragmentation. Furthermore, this requirement presents substantial therapeutic challenges owing to the need for persistent and complete caspase blockade.


Cell | 1990

Early steps in mitochondrial protein import: Receptor functions can be substituted by the membrane insertion activity of apocytochrome c

Rosemary A. Stuart; Donald W. Nicholson; Walter Neupert

The process of insertion of precursor proteins into mitochondrial membranes was investigated using a hybrid protein (pSc1-c) that contains dual targeting information and, at the same time, membrane insertion activity. pSc1-c is composed of the matrix-targeting domain of the cytochrome c1 presequence joined to the amino terminus of apocytochrome c. It can be selectively imported along either a cytochrome c1 route into the mitochondrial matrix or via the cytochrome c route into the intermembrane space. In contrast to cytochrome c1, pSc1-c does not require the receptor system/GIP for entry into the matrix. The apocytochrome c in the pSc1-c fusion protein appears to exert its membrane insertion activity in such a manner that the matrix-targeting sequence gains direct access to the membrane potential-dependent step. These results attribute an essential function to the receptor system in facilitating the initial insertion of precursors into the mitochondrial membranes.


The Journal of Neuroscience | 2005

Axonal Dynactin p150Glued Transports Caspase-8 to Drive Retrograde Olfactory Receptor Neuron Apoptosis

Christine Carson; Maya Saleh; Donald W. Nicholson; A. Jane Roskams

Olfactory receptor neurons (ORNs) undergo caspase-mediated retrograde apoptosis after target removal (bulbectomy), in which axonal caspase-9 and caspase-3 activation leads to terminal apoptosis in ORN soma of the olfactory epithelium. Here, we show that caspase-8 can act as an initiator of ORN apoptosis after bulbectomy and also after synaptic instability is induced by NMDA-mediated excitotoxic death of ORN target neurons in the olfactory bulb. Caspase-8 and caspase-3 are sequentially activated within ORN presynaptic terminals, and caspase-8 complexes with dynactin p150Glued, (a retrograde motor protein) and is transported retrogradely, preceding axonal caspase-3 activation and apoptosis of ORN cell bodies. Focal in vivo inhibition of initiator caspase activation or microtubule-dependent transport (with Taxol) at the lesioned axon terminus results in a significant reduction in retrograde axonal caspase-8 and caspase-3 activation and inhibition of retrograde ORN death. Caspase-8 activation and retrograde transport after NMDA lesion is similarly reduced in mice null for p75, the low-affinity nerve growth factor receptor. The retrograde apoptosis of ORNs thus involves a novel mechanism that used p75 in the local activation of caspase-8. Once caspase-8 is maximally activated in the presynaptic terminal, it is transported retrogradely by the motor complex dynactin/dynein, a process that can be inhibited focally to inhibit ORN apoptosis after acute axonal lesion. These data have revealed a novel mechanism of retrograde apoptosis, in which caspase-8 complexes directly with axonal dynactin p150Glued to reveal a differential vulnerability of subpopulations of ORNs to undergo apoptosis after axonal damage and the loss of olfactory bulb target neurons.


Proceedings of the National Academy of Sciences of the United States of America | 2008

Confinement of caspase-12 proteolytic activity to autoprocessing

Sophie Roy; Jeffrey R. Sharom; Caroline Houde; Thomas P. Loisel; John P. Vaillancourt; Wei Shao; Maya Saleh; Donald W. Nicholson

Caspase-12 is a dominant-negative regulator of caspase-1 (IL-1β-converting enzyme) and an attenuator of cytokine responsiveness to septic infections. This molecular role for caspase-12 appears to be akin to the role of cFLIP in regulating caspase-8 in the extrinsic cell death pathway; however, unlike cFLIP/Usurpin, we demonstrate here that caspase-12 is catalytically competent. To examine these catalytic properties, rat caspase-12 was cloned, and the recombinant enzyme was used to examine the cleavage of macromolecular and synthetic fluorogenic substrates. Although caspase-12 could mediate autoproteolytic maturation of its own proenzyme, in both cis and trans, it was not able to cleave any other polypeptide substrate, including other caspase proenzymes, apoptotic substrates, cytokine precursors, or proteins in the endoplasmic reticulum that normally undergo caspase-mediated proteolysis. The dearth of potential substrates for caspase-12 also was confirmed by whole-cell diagonal-gel analysis. Autolytic cleavage within the caspase-12 proenzyme was mapped to a single site at the large–small subunit junction, ATAD319, and this motif was recognized by caspase-12 when incorporated into synthetic fluorogenic substrates. The specific activity of caspase-12 with these substates was several orders of magnitude lower than caspases-1 and -3, highlighting its relative catalytic paucity. In intact cells, caspase-12 autoproteolysis occurred in the inhibitory complex containing caspase-1. We propose that the proteolytic activity of caspase-12 is confined to its own proenzyme and that autocleavage within the caspase-1 complex may be a means for temporal limitation of the inhibitory effects of caspase-12 on proinflammatory cytokine maturation.


Nature | 2013

Corrigendum: Enhanced bacterial clearance and sepsis resistance in caspase-12-deficient mice

Maya Saleh; John C. Mathison; Melissa K. Wolinski; Steve J. Bensinger; Patrick Fitzgerald; Nathalie Droin; Richard J. Ulevitch; Douglas R. Green; Donald W. Nicholson

This corrects the article DOI: 10.1038/nature04656


Archive | 1987

NADH: A Common Requirement for the Import and Maturation of Cytochromes c and c1

Donald W. Nicholson; Joachim Ostermann; Walter Neupert

The covalent attachment of heme to apocytochrome c, which is catalyzed by the mitochondrial enzyme cytochrome c heme lyase, was dependent on NADH. In addition, a cofactor present in reticulocyte lysate or a Neurospora crassa cytosol fraction was required for the NADH-dependent step. In the absence of NADH, apocytochrome c was bound to the mitochondrial surface and remained accessible to externally added proteases. In the presence of NADH, covalent attachment of heme occurred with concomitant translocation of cytochrome c across the outer mitochondrial membrane to a protease-resistant location. Both heme attachment and translocation were inhibited by the heme analogue deuterohemin.


Archive | 1997

A combinatorial approach defines specificities of members of the caspase family and granzyme B

Nancy A. Thornberry; Thomas A. Rano; Eric Peterson; Dita M. Rasper; Tracy Timkey; Margarita Garcia-Calvo; Vicky M. Houtzager; Patricia A. Nordstrom; Sophie Roy; John P. Vaillancourt; Kevin T. Chapman; Donald W. Nicholson

Collaboration


Dive into the Donald W. Nicholson's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar

Sophie Roy

Johns Hopkins University School of Medicine

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Yongxin Han

Washington University in St. Louis

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

John Colucci

Washington University in St. Louis

View shared research outputs
Researchain Logo
Decentralizing Knowledge