Robert Korneluk | University of Ottawa | Université d'Ottawa (original) (raw)

Papers by Robert Korneluk

Seminars in cell & developmental biology, 2015

Apoptosis : an international journal on programmed cell death, 2001

The X-linked Inhibitor of Apoptosis, XIAP, is a key member of the newly discovered family of intr... more The X-linked Inhibitor of Apoptosis, XIAP, is a key member of the newly discovered family of intrinsic inhibitors of apoptosis (IAP) proteins. IAPs block cell death both in vitro and in vivo by virtue of inhibition of distinct caspases. Although other proteins have been identified which inhibit upstream caspases, only the IAPs have been demonstrated to be endogenous repressors of the terminal caspase cascade. In turn, the caspase inhibiting activity of XIAP is negatively regulated by at least two XIAP-interacting proteins, XAF1 and Smac/DIABLO. In addition to the inhibition of caspases, recent discoveries from several laboratories suggest that XIAP is also involved in a number of other biologically significant cellular activities including modulation of receptor-mediated signal transduction and protein ubiquitination. XIAP is also translated by a rare cap-independent mechanism mediated by a specific sequence called IRES (for Internal Ribosome Entry Site) which is found in the XIAP 5...

The Journal of neuroscience : the official journal of the Society for Neuroscience, Jan 15, 1999

Transient forebrain ischemia produced by four-vessel occlusion (4-VO) triggers the delayed death ... more Transient forebrain ischemia produced by four-vessel occlusion (4-VO) triggers the delayed death of CA1 neurons in the hippocampus, resulting in behavioral deficits of spatial learning performance. We demonstrate that CA1 neuronal loss induced by 4-VO (12 min) is preceded by a selective and marked elevation of catalytically active caspase-3 in these neurons, indicative of apoptosis. Virally mediated overexpression of the anti-apoptotic gene X chromosome-linked inhibitor of apoptosis protein (XIAP) prevented both the production of catalytically active caspase-3 and degeneration of CA1 neurons after transient forebrain ischemia. CA1 neurons protected in this manner appeared to function normally, as assessed by immunohistochemical detection of the neuronal activity marker nerve growth factor inducible-A and by spatial learning performance in the Morris water maze. These findings indicate that caspase-3 activation is a key event in ischemic neuronal death and that blockade of this event...

Apoptosis, 1997

Multicellular organisms have evolved elaborate signal transduction pathways for maintaining homeo... more Multicellular organisms have evolved elaborate signal transduction pathways for maintaining homeostasis through the control of cell proliferation and death. The recent surge of interest in the regulation of programmed cell death has led to the rapid identification of many proteins involved in controlling and executing apoptosis. The inhibitors of apoptosis proteins (IAPs) constitute a family of highly conserved death suppressing

Experientia Supplementum, 2006

A conceptual shift has occurred in recent years from considering cancer as simply a disease of de... more A conceptual shift has occurred in recent years from considering cancer as simply a disease of deregulated cell proliferation to a view that incorporates the aberrant control of apoptosis into the equation. Apoptosis is an organized, genetically programmed cell death process by which multicellular organisms specifically destroy, dismantle and dispose of cells. In cancer cells, this tightly controlled process is suppressed by genetic lesions, allowing cancer cells to survive beyond their normal life span even in hostile environments that are prone to hypoxia and lack many trophic factor supports. In the last two decades, cancer researchers have made great strides in our understanding of the underlying molecular mechanism of apoptosis in chemoresistance generation and tumorigenesis. This tremendous increase in our knowledge of apoptosis in tumors has greatly impacted our perspective on carcinogenesis. Key regulators of apoptosis such as members of the Inhibitors of Apoptosis family and Bcl-2 family have been shown to play a pivotal role in allowing most cancer cells to escape apoptosis. The identification of specific targets involved in the suppression of apoptosis in cancer cells has facilitated the design and development of therapeutic strategies based on rational molecular approaches that aim to modulate apoptotic pathways. Many promising apoptosis-dependent strategies have been translated into clinical trials in the continued assessment of regimens that can effectively eradicate cancers.

OncoImmunology, 2014

A dual immunotherapy approach employing small-molecule inhibitors of apoptosis (IAP) protein anta... more A dual immunotherapy approach employing small-molecule inhibitors of apoptosis (IAP) protein antagonists in combination with innate immune stimuli has proven to be highly synergistic and effective in animal tumor models. This strategy overcomes many of the limitations of either single agent therapy and our results suggest that the combination could be easily and effectively translated to the clinic.

The inhibitor of apoptosis (IAP) gene family is characterized by the presence of a BIR zinc-finge... more The inhibitor of apoptosis (IAP) gene family is characterized by the presence of a BIR zinc-finger domain. In this chapter, we discuss how the IAPs, through multiple mechanisms, are able to suppress apoptosis as just one of their many functions. The IAPs also affect signal transduction pathways, differentiation, immunity, and proliferation. The IAPs are central to the regulation of apoptosis,

PLOS One, 2007

BackgroundRetinitis pigmentosa (RP) is a blinding genetic disorder that is caused by the death of... more BackgroundRetinitis pigmentosa (RP) is a blinding genetic disorder that is caused by the death of photoreceptors in the outer nuclear layer of the retina. To date, 39 different genetic loci have been associated with the disease, and 28 mutated genes have been identified. Despite the complexity of the underlying genetic basis for RP, the final common pathway is photoreceptor cell

Frontiers in Immunology, 2014

Mammalian skeletal muscle maintains a robust regenerative capacity throughout life, largely due t... more Mammalian skeletal muscle maintains a robust regenerative capacity throughout life, largely due to the presence of a stem cell population known as "satellite cells" in the muscle milieu. In normal conditions, these cells remain quiescent; they are activated upon injury to become myoblasts, which proliferate extensively and eventually differentiate and fuse to form new multinucleated muscle fibers. Recent findings have identified some of the factors, including the cytokine TNFα-like weak inducer of apoptosis (TWEAK), which govern these cells' decisions to proliferate, differentiate, or fuse. In this review, we will address the functions of TWEAK, its receptor Fn14, and the associated signal transduction molecule, the cellular inhibitor of apoptosis 1 (cIAP1), in the regulation of myogenesis. TWEAK signaling can activate the canonical NF-κB signaling pathway, which promotes myoblast proliferation and inhibits myogenesis. In addition, TWEAK activates the non-canonical NF-κB pathway, which, in contrast, promotes myogenesis by increasing myoblast fusion. Both pathways are regulated by cIAP1, which is an essential component of downstream signaling mediated by TWEAK and similar cytokines. This review will focus on the seemingly contradictory roles played by TWEAK during muscle regeneration, by highlighting the interplay between the two NF-κB pathways under physiological and pathological conditions. We will also discuss how myogenesis is negatively affected by chronic conditions, which affect homeostasis of the skeletal muscle environment.

PURPOSE. To evaluate the neuroprotective effects of adenoasso- ciated virus delivery of XIAP in N... more PURPOSE. To evaluate the neuroprotective effects of adenoasso- ciated virus delivery of XIAP in N-methyl-N-nitrosourea (MNU)- induced retinal degeneration in Sprague-Dawley rats. METHODS. Sprague-Dawley rats were injected subretinally with recombinant adenoassociated virus (rAAV) encoding either XIAP or green fluorescent protein (GFP; injection control). Six weeks after injection, the animals received an intraperitoneal injection of MNU, a DNA methylating agent, at

Genomics, 2001

Here we report the genomic organization and mapping of the X-linked inhibitor of apoptosis gene (... more Here we report the genomic organization and mapping of the X-linked inhibitor of apoptosis gene (BIRC4, also known as XIAP and hILP) and the identification of a closely related transcript. BIRC4 is located on Xq25 and is composed of seven exons.The intron/exon structure is highly conserved between the mouse homologue and its human counterpart. Four bands cross-react with a BIRC4

Genomics, 2000

X-linked inhibitor of apoptosis protein (XIAP) is a potent modulator of programmed cell death. XI... more X-linked inhibitor of apoptosis protein (XIAP) is a potent modulator of programmed cell death. XIAP specifically binds and inhibits the function of caspase-3, -7, and -9, key effector proteases of apoptosis. We recently isolated, by yeast two-hybrid screening, a novel 34-kDa zinc finger protein, XIAP-associated factor 1 (XAF1). Both the caspase inhibiting and the anti-apoptotic abilities of XIAP were found

Nature, 1996

Dysregulation of apoptosis can result in inappropriate suppression of cell death, as occurs in th... more Dysregulation of apoptosis can result in inappropriate suppression of cell death, as occurs in the development of some cancers, or in failure to control the extent of cell death, as is believed to occur in acquired immunodeficiency and certain neurodegenerative disorders, such as spinal muscular atrophy (SMA). Recently, we isolated a candidate gene, encoding neuronal apoptosis inhibitor protein (NAIP), for SMA. This gene is homologous to two baculovirus inhibitor of apoptosis proteins (Cp-IAP and Op-IAP) and is partly deleted in individuals with type I SMA. A second SMA candidate gene encoding survival motor neuron (SMN), which is contiguous with the NAIP locus on 5q13.1, was also reported. Here we demonstrate a NAIP-mediated inhibition of apoptosis induced by a variety of signals, and have identified three additional human complementary DNAs and a Drosophila melanogaster sequence that are also homologous to the baculovirus IAPs. The four open reading frames (ORFs) possess three baculoviral inhibition of apoptosis protein repeat (BIR) domains and a carboxy-terminal RING zinc-finger. The human iap genes have a distinct but overlapping pattern of expression in fetal and adult tissues. These proteins significantly increase the number of known apoptotic suppressors.

Journal of Neuroscience, 2004

neuronal apoptosis inhibitory protein, human IAP1 (HIAP1), and HIAP2] during postnatal developmen... more neuronal apoptosis inhibitory protein, human IAP1 (HIAP1), and HIAP2] during postnatal development as opposed to XAF1, which decreased during the same period; there was no significant alteration in either Smac/DIABO or Omi/HtrA2. The regulation of IAPs and XAF1 varied after axotomy of the sciatic nerve; in the neonate, there was a significant loss of IAP in the injured motoneurons as opposed to the adult, in which there was only a moderate decrease. By overexpressing exogenous IAPs in neonatal axotomized motoneurons, it was possible to delay motoneuron cell death . In opposition, the overexpression of exogenous XAF1 in adult motoneurons totally abrogated the natural resistance of these cells to axotomy. The degradation in the adult, induced by XAF1, could be overcome by simultaneously expressing high levels of exogenous XIAP in adult motoneurons. These experiments suggest that it may be the ratio between XAF1 and XIAP that confers the resistance of adult motoneurons to axotomy. In addition, the regulation in the levels of IAPs and XAF1 may be essential in the cell death mechanism of injured motoneurons.

Science, 1993

Myotonic dystrophy (DM) is an autosomal-dominant disorder that affects 1 in 8000 individuals. Amp... more Myotonic dystrophy (DM) is an autosomal-dominant disorder that affects 1 in 8000 individuals. Amplification of an unstable trinucleotide CTG repeat, located within the 3' untranslated region of a gene, correlates with a more severe DM phenotype. In three cases, the number of CTG repeats was reduced during the transmission of the DM allele; in one of these cases, the number was reduced to within the normal range and correlated at least with a delay in the onset of clinical signs of DM. Haplotype data of six polymorphic markers in the DM gene region indicate that, in this latter case, two stretches of the affected chromosome had been exchanged with that region of the wild-type chromosome.

Science, 1992

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, a... more JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.

Science, 1992

J. Am. Chem. Soc. 86, 3697 (1964)]. Alaninamide increased kS,, equally for the hydrolysis of both... more J. Am. Chem. Soc. 86, 3697 (1964)]. Alaninamide increased kS,, equally for the hydrolysis of both sucAAPF-SBzl and sucAAPF-AMC by Ch, which indicates that deacylation is rate determining for both compounds. Alaninamide also increased kcat for the hydrolysis ofsucAAPF-SBzl by D189S and mutant Tr-*Ch[S1+L1+L2], which confirms that deacylation is the rate determining step in these reactions (L. Hedstrom, unpublished experiments). 20. In the elastase reaction, increasing peptide length also increases acylation in preference to binding or deacylation [R. . 22. Acetylcholinesterase hydrolyzes acetylcholine 105fold faster than the analogous amide (kc.JKm), which is consistent with the relative reactivity of esters and amides [D. E. Moore and G. P. Hess, Biochemistry 14, 2386 (1975]. In contrast, Ch hydrolyzes sucAAPF-SBzl only sixfold faster than sucAAPF-pNA. 23. R. A. Blevins and A. Tulinsky, J. Biol. Chem. 260, 4264 (1985). 24. P. G. Jones and A. J. Kirby, J. Chem. Soc. Chem. Commun. 1979Commun. , 288 (1979. 25. We found that Tr, D189S, and Tr->Ch[S1+L1 +L2] were also expressed in yeast culture medium by fusing the trypsinogen coding sequences to the a-factor leader sequence as described for carboxypeptidase Al [M. A. Phillips, R. Fletterick, W. J. Rutter, J. Biol. Chem. 265, 20692 (1990)]. The final expression vector pYT contains the inducible alcohol dehydrogenase-glyceraldehydephosphate dehydrogenase (ADH-GAPDH) promoter and regulatory regions, the GAPDH transcription terminator, and amp, ura3, and leu2d markers. Medium was isolated from a 2-liter culture by centrifugation and was concentrated on a phenyl-Sepharose column.

RNA, 2006

The cell has many ways to regulate the production of proteins. One mechanism is through the chang... more The cell has many ways to regulate the production of proteins. One mechanism is through the changes to the machinery of translation initiation. These alterations favor the translation of one subset of mRNAs over another. It was first shown that internal ribosome entry sites (IRESes) within viral RNA genomes allowed the production of viral proteins more efficiently than most of the host proteins. The RNA secondary structure of viral IRESes has sometimes been conserved between viral species even though the primary sequences differ. These structures are important for IRES function, but no similar structure conservation has yet to be shown in cellular IRES. With the advances in mathematical modeling and computational approaches to complex biological problems, is there a way to predict an IRES in a data set of unknown sequences? This review examines what is known about cellular IRES structures, as well as the data sets and tools available to examine this question. We find that the lengths, number of upstream AUGs, and %GC content of 59-UTRs of the human transcriptome have a similar distribution to those of published IRES-containing UTRs. Although the UTRs containing IRESes are on the average longer, almost half of all 59-UTRs are long enough to contain an IRES. Examination of the available RNA structure prediction software and RNA motif searching programs indicates that while these programs are useful tools to fine tune the empirically determined RNA secondary structure, the accuracy of de novo secondary structure prediction of large RNA molecules and subsequent identification of new IRES elements by computational approaches, is still not possible. .

Seminars in cell & developmental biology, 2015

Apoptosis : an international journal on programmed cell death, 2001

The X-linked Inhibitor of Apoptosis, XIAP, is a key member of the newly discovered family of intr... more The X-linked Inhibitor of Apoptosis, XIAP, is a key member of the newly discovered family of intrinsic inhibitors of apoptosis (IAP) proteins. IAPs block cell death both in vitro and in vivo by virtue of inhibition of distinct caspases. Although other proteins have been identified which inhibit upstream caspases, only the IAPs have been demonstrated to be endogenous repressors of the terminal caspase cascade. In turn, the caspase inhibiting activity of XIAP is negatively regulated by at least two XIAP-interacting proteins, XAF1 and Smac/DIABLO. In addition to the inhibition of caspases, recent discoveries from several laboratories suggest that XIAP is also involved in a number of other biologically significant cellular activities including modulation of receptor-mediated signal transduction and protein ubiquitination. XIAP is also translated by a rare cap-independent mechanism mediated by a specific sequence called IRES (for Internal Ribosome Entry Site) which is found in the XIAP 5...

The Journal of neuroscience : the official journal of the Society for Neuroscience, Jan 15, 1999

Transient forebrain ischemia produced by four-vessel occlusion (4-VO) triggers the delayed death ... more Transient forebrain ischemia produced by four-vessel occlusion (4-VO) triggers the delayed death of CA1 neurons in the hippocampus, resulting in behavioral deficits of spatial learning performance. We demonstrate that CA1 neuronal loss induced by 4-VO (12 min) is preceded by a selective and marked elevation of catalytically active caspase-3 in these neurons, indicative of apoptosis. Virally mediated overexpression of the anti-apoptotic gene X chromosome-linked inhibitor of apoptosis protein (XIAP) prevented both the production of catalytically active caspase-3 and degeneration of CA1 neurons after transient forebrain ischemia. CA1 neurons protected in this manner appeared to function normally, as assessed by immunohistochemical detection of the neuronal activity marker nerve growth factor inducible-A and by spatial learning performance in the Morris water maze. These findings indicate that caspase-3 activation is a key event in ischemic neuronal death and that blockade of this event...

Apoptosis, 1997

Multicellular organisms have evolved elaborate signal transduction pathways for maintaining homeo... more Multicellular organisms have evolved elaborate signal transduction pathways for maintaining homeostasis through the control of cell proliferation and death. The recent surge of interest in the regulation of programmed cell death has led to the rapid identification of many proteins involved in controlling and executing apoptosis. The inhibitors of apoptosis proteins (IAPs) constitute a family of highly conserved death suppressing

Experientia Supplementum, 2006

A conceptual shift has occurred in recent years from considering cancer as simply a disease of de... more A conceptual shift has occurred in recent years from considering cancer as simply a disease of deregulated cell proliferation to a view that incorporates the aberrant control of apoptosis into the equation. Apoptosis is an organized, genetically programmed cell death process by which multicellular organisms specifically destroy, dismantle and dispose of cells. In cancer cells, this tightly controlled process is suppressed by genetic lesions, allowing cancer cells to survive beyond their normal life span even in hostile environments that are prone to hypoxia and lack many trophic factor supports. In the last two decades, cancer researchers have made great strides in our understanding of the underlying molecular mechanism of apoptosis in chemoresistance generation and tumorigenesis. This tremendous increase in our knowledge of apoptosis in tumors has greatly impacted our perspective on carcinogenesis. Key regulators of apoptosis such as members of the Inhibitors of Apoptosis family and Bcl-2 family have been shown to play a pivotal role in allowing most cancer cells to escape apoptosis. The identification of specific targets involved in the suppression of apoptosis in cancer cells has facilitated the design and development of therapeutic strategies based on rational molecular approaches that aim to modulate apoptotic pathways. Many promising apoptosis-dependent strategies have been translated into clinical trials in the continued assessment of regimens that can effectively eradicate cancers.

OncoImmunology, 2014

A dual immunotherapy approach employing small-molecule inhibitors of apoptosis (IAP) protein anta... more A dual immunotherapy approach employing small-molecule inhibitors of apoptosis (IAP) protein antagonists in combination with innate immune stimuli has proven to be highly synergistic and effective in animal tumor models. This strategy overcomes many of the limitations of either single agent therapy and our results suggest that the combination could be easily and effectively translated to the clinic.

The inhibitor of apoptosis (IAP) gene family is characterized by the presence of a BIR zinc-finge... more The inhibitor of apoptosis (IAP) gene family is characterized by the presence of a BIR zinc-finger domain. In this chapter, we discuss how the IAPs, through multiple mechanisms, are able to suppress apoptosis as just one of their many functions. The IAPs also affect signal transduction pathways, differentiation, immunity, and proliferation. The IAPs are central to the regulation of apoptosis,

PLOS One, 2007

BackgroundRetinitis pigmentosa (RP) is a blinding genetic disorder that is caused by the death of... more BackgroundRetinitis pigmentosa (RP) is a blinding genetic disorder that is caused by the death of photoreceptors in the outer nuclear layer of the retina. To date, 39 different genetic loci have been associated with the disease, and 28 mutated genes have been identified. Despite the complexity of the underlying genetic basis for RP, the final common pathway is photoreceptor cell

Frontiers in Immunology, 2014

Mammalian skeletal muscle maintains a robust regenerative capacity throughout life, largely due t... more Mammalian skeletal muscle maintains a robust regenerative capacity throughout life, largely due to the presence of a stem cell population known as "satellite cells" in the muscle milieu. In normal conditions, these cells remain quiescent; they are activated upon injury to become myoblasts, which proliferate extensively and eventually differentiate and fuse to form new multinucleated muscle fibers. Recent findings have identified some of the factors, including the cytokine TNFα-like weak inducer of apoptosis (TWEAK), which govern these cells' decisions to proliferate, differentiate, or fuse. In this review, we will address the functions of TWEAK, its receptor Fn14, and the associated signal transduction molecule, the cellular inhibitor of apoptosis 1 (cIAP1), in the regulation of myogenesis. TWEAK signaling can activate the canonical NF-κB signaling pathway, which promotes myoblast proliferation and inhibits myogenesis. In addition, TWEAK activates the non-canonical NF-κB pathway, which, in contrast, promotes myogenesis by increasing myoblast fusion. Both pathways are regulated by cIAP1, which is an essential component of downstream signaling mediated by TWEAK and similar cytokines. This review will focus on the seemingly contradictory roles played by TWEAK during muscle regeneration, by highlighting the interplay between the two NF-κB pathways under physiological and pathological conditions. We will also discuss how myogenesis is negatively affected by chronic conditions, which affect homeostasis of the skeletal muscle environment.

PURPOSE. To evaluate the neuroprotective effects of adenoasso- ciated virus delivery of XIAP in N... more PURPOSE. To evaluate the neuroprotective effects of adenoasso- ciated virus delivery of XIAP in N-methyl-N-nitrosourea (MNU)- induced retinal degeneration in Sprague-Dawley rats. METHODS. Sprague-Dawley rats were injected subretinally with recombinant adenoassociated virus (rAAV) encoding either XIAP or green fluorescent protein (GFP; injection control). Six weeks after injection, the animals received an intraperitoneal injection of MNU, a DNA methylating agent, at

Genomics, 2001

Here we report the genomic organization and mapping of the X-linked inhibitor of apoptosis gene (... more Here we report the genomic organization and mapping of the X-linked inhibitor of apoptosis gene (BIRC4, also known as XIAP and hILP) and the identification of a closely related transcript. BIRC4 is located on Xq25 and is composed of seven exons.The intron/exon structure is highly conserved between the mouse homologue and its human counterpart. Four bands cross-react with a BIRC4

Genomics, 2000

X-linked inhibitor of apoptosis protein (XIAP) is a potent modulator of programmed cell death. XI... more X-linked inhibitor of apoptosis protein (XIAP) is a potent modulator of programmed cell death. XIAP specifically binds and inhibits the function of caspase-3, -7, and -9, key effector proteases of apoptosis. We recently isolated, by yeast two-hybrid screening, a novel 34-kDa zinc finger protein, XIAP-associated factor 1 (XAF1). Both the caspase inhibiting and the anti-apoptotic abilities of XIAP were found

Nature, 1996

Dysregulation of apoptosis can result in inappropriate suppression of cell death, as occurs in th... more Dysregulation of apoptosis can result in inappropriate suppression of cell death, as occurs in the development of some cancers, or in failure to control the extent of cell death, as is believed to occur in acquired immunodeficiency and certain neurodegenerative disorders, such as spinal muscular atrophy (SMA). Recently, we isolated a candidate gene, encoding neuronal apoptosis inhibitor protein (NAIP), for SMA. This gene is homologous to two baculovirus inhibitor of apoptosis proteins (Cp-IAP and Op-IAP) and is partly deleted in individuals with type I SMA. A second SMA candidate gene encoding survival motor neuron (SMN), which is contiguous with the NAIP locus on 5q13.1, was also reported. Here we demonstrate a NAIP-mediated inhibition of apoptosis induced by a variety of signals, and have identified three additional human complementary DNAs and a Drosophila melanogaster sequence that are also homologous to the baculovirus IAPs. The four open reading frames (ORFs) possess three baculoviral inhibition of apoptosis protein repeat (BIR) domains and a carboxy-terminal RING zinc-finger. The human iap genes have a distinct but overlapping pattern of expression in fetal and adult tissues. These proteins significantly increase the number of known apoptotic suppressors.

Journal of Neuroscience, 2004

neuronal apoptosis inhibitory protein, human IAP1 (HIAP1), and HIAP2] during postnatal developmen... more neuronal apoptosis inhibitory protein, human IAP1 (HIAP1), and HIAP2] during postnatal development as opposed to XAF1, which decreased during the same period; there was no significant alteration in either Smac/DIABO or Omi/HtrA2. The regulation of IAPs and XAF1 varied after axotomy of the sciatic nerve; in the neonate, there was a significant loss of IAP in the injured motoneurons as opposed to the adult, in which there was only a moderate decrease. By overexpressing exogenous IAPs in neonatal axotomized motoneurons, it was possible to delay motoneuron cell death . In opposition, the overexpression of exogenous XAF1 in adult motoneurons totally abrogated the natural resistance of these cells to axotomy. The degradation in the adult, induced by XAF1, could be overcome by simultaneously expressing high levels of exogenous XIAP in adult motoneurons. These experiments suggest that it may be the ratio between XAF1 and XIAP that confers the resistance of adult motoneurons to axotomy. In addition, the regulation in the levels of IAPs and XAF1 may be essential in the cell death mechanism of injured motoneurons.

Science, 1993

Myotonic dystrophy (DM) is an autosomal-dominant disorder that affects 1 in 8000 individuals. Amp... more Myotonic dystrophy (DM) is an autosomal-dominant disorder that affects 1 in 8000 individuals. Amplification of an unstable trinucleotide CTG repeat, located within the 3' untranslated region of a gene, correlates with a more severe DM phenotype. In three cases, the number of CTG repeats was reduced during the transmission of the DM allele; in one of these cases, the number was reduced to within the normal range and correlated at least with a delay in the onset of clinical signs of DM. Haplotype data of six polymorphic markers in the DM gene region indicate that, in this latter case, two stretches of the affected chromosome had been exchanged with that region of the wild-type chromosome.

Science, 1992

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, a... more JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.

Science, 1992

J. Am. Chem. Soc. 86, 3697 (1964)]. Alaninamide increased kS,, equally for the hydrolysis of both... more J. Am. Chem. Soc. 86, 3697 (1964)]. Alaninamide increased kS,, equally for the hydrolysis of both sucAAPF-SBzl and sucAAPF-AMC by Ch, which indicates that deacylation is rate determining for both compounds. Alaninamide also increased kcat for the hydrolysis ofsucAAPF-SBzl by D189S and mutant Tr-*Ch[S1+L1+L2], which confirms that deacylation is the rate determining step in these reactions (L. Hedstrom, unpublished experiments). 20. In the elastase reaction, increasing peptide length also increases acylation in preference to binding or deacylation [R. . 22. Acetylcholinesterase hydrolyzes acetylcholine 105fold faster than the analogous amide (kc.JKm), which is consistent with the relative reactivity of esters and amides [D. E. Moore and G. P. Hess, Biochemistry 14, 2386 (1975]. In contrast, Ch hydrolyzes sucAAPF-SBzl only sixfold faster than sucAAPF-pNA. 23. R. A. Blevins and A. Tulinsky, J. Biol. Chem. 260, 4264 (1985). 24. P. G. Jones and A. J. Kirby, J. Chem. Soc. Chem. Commun. 1979Commun. , 288 (1979. 25. We found that Tr, D189S, and Tr->Ch[S1+L1 +L2] were also expressed in yeast culture medium by fusing the trypsinogen coding sequences to the a-factor leader sequence as described for carboxypeptidase Al [M. A. Phillips, R. Fletterick, W. J. Rutter, J. Biol. Chem. 265, 20692 (1990)]. The final expression vector pYT contains the inducible alcohol dehydrogenase-glyceraldehydephosphate dehydrogenase (ADH-GAPDH) promoter and regulatory regions, the GAPDH transcription terminator, and amp, ura3, and leu2d markers. Medium was isolated from a 2-liter culture by centrifugation and was concentrated on a phenyl-Sepharose column.

RNA, 2006

The cell has many ways to regulate the production of proteins. One mechanism is through the chang... more The cell has many ways to regulate the production of proteins. One mechanism is through the changes to the machinery of translation initiation. These alterations favor the translation of one subset of mRNAs over another. It was first shown that internal ribosome entry sites (IRESes) within viral RNA genomes allowed the production of viral proteins more efficiently than most of the host proteins. The RNA secondary structure of viral IRESes has sometimes been conserved between viral species even though the primary sequences differ. These structures are important for IRES function, but no similar structure conservation has yet to be shown in cellular IRES. With the advances in mathematical modeling and computational approaches to complex biological problems, is there a way to predict an IRES in a data set of unknown sequences? This review examines what is known about cellular IRES structures, as well as the data sets and tools available to examine this question. We find that the lengths, number of upstream AUGs, and %GC content of 59-UTRs of the human transcriptome have a similar distribution to those of published IRES-containing UTRs. Although the UTRs containing IRESes are on the average longer, almost half of all 59-UTRs are long enough to contain an IRES. Examination of the available RNA structure prediction software and RNA motif searching programs indicates that while these programs are useful tools to fine tune the empirically determined RNA secondary structure, the accuracy of de novo secondary structure prediction of large RNA molecules and subsequent identification of new IRES elements by computational approaches, is still not possible. .