- Email: [email protected]
Gene therapy saves failing hearts
250
News & Comment
TRENDS in Genetics Vol.17 No.5 May 2001
Fatal embrace: structural basis of caspase inhibition Strict control of programmed cell death (apoptosis) is essential for the homeostasis and survival of multicellular organisms. The unchecked progression of apoptosis can have dire consequences – too much cell death is often associated with the destruction of healthy cells and tissues (as in neurodegenerative disorders and autoimmune disease); conversely, too little cell death is suspected to be partly responsible for the uncontrolled proliferation of cancer cells. Several of the players that are involved in apoptosis have been identified and now the new data are beginning to unravel their intricate interplay. The apoptotic process is dependent on specific cysteine proteases, known as caspases, that both initiate (initiator caspases, e.g. caspase-9) and execute (effector caspases, e.g. caspase-3,-7) the orderly dismantling of apoptotic cells. Opposing this cellular destruction are two classes of cellular apoptotic inhibitors – members of the BCL-2 and ‘Inhibitor of Apoptosis’ (IAP) families. Whereas the BCL-2 proteins can block the mitochondrial branch of apoptosis by preventing the release of cytochrome c, the IAPs block both the mitochondrion- and
receptor-mediated pathways of apoptosis by binding directly to and inhibiting the initiator and effector caspases. Recently, ground-breaking studies have revealed the structural basis for the inhibition of the effector caspases by the prototype of the IAP family, XIAP. Chai et al. and Huang et al. now reveal the crystal structure of caspase-7 complexed with the inhibitory fragment of XIAP, showing that the XIAP peptide binds the catalytic groove of caspase-7, completely filling the active site and thus blocking substrate entry. Riedl et al. find a similar structural arrangement between XIAP and caspase-3, which is not surprising considering that caspase-3 and caspase-7 share 54% sequence identity and have nearly identical backbone structures. Interestingly, the binding of XIAP is antiparallel to the binding of the natural caspase substrates. Nevertheless, the interactions between caspase-3 or -7 and XIAP are very similar to the binding of caspases and their tetrapeptide inhibitor DEVD-CHO. Unexpectedly, however, XIAP binds to caspases-3 and -7 via the short linker region that precedes the BIR2 (baculoviral IAP repeat, named for its homology to baculoviral IAPs) domain – the
BIR2 domain itself was found to be dispensable and could be replaced with an unrelated protein, such as glutathione S-transferase (GST). The BIR2 domain is now proposed to stabilize the interaction between caspase and XIAP. Significantly, the inhibitor of XIAP called Smac/DIABLO can bind to the BIR2 domain. The interaction of Smac/DIABLO with XIAP is proposed to destabilize the XIAP–caspase-3/-7 interaction and thus liberate XIAP from caspase’s embrace and restore caspase activity. The understanding of the interaction between XIAP and effector caspases further advances our knowledge of programmed cell death and its control. More importantly, it sets the stage for the discovery and rational design of novel peptide caspase inhibitors.
‘Genes were easy’ – the launch of the Human Proteome Organization
Gene therapy saves failing hearts
1 Chai, J. et al. (2001) Structural basis of caspase7 inhibition by XIAP. Cell 104, 769–780 2 Huang, Y. et al. (2001) Structural basis of caspase inhibition by XIAP: differential roles of the linker versus the BIR domain. Cell 104, 781–790 3 Riedl, S. et al. (2001) Structural basis for the inhibition of caspase-3 by XIAP. Cell 104, 791–800
Martin Holcik [email protected]
Journal Club
No rat race The relationship between Celera Genomics and the publicly funded sequencing projects has changed. In contrast to their sometimes rancorous race to sequence the human genome, Celera will now share a $58 million grant with the Baylor University Center of the Human Genome Project to sequence the rat genome. Celera will sequence fragments of the rat genome and Baylor will assemble the fragmented sequence. Both sides will make their information available to the public on the NIH database. In addition to its importance in comparative and evolutionary genomic studies, the rat genomic sequence is valuable because the rat has long been a standard model for medical and pharmaceutical testing. Expect a draft sequence of the rat genome in two years. NJ
Under the slogan ‘Genes were easy’, the Human Proteome Organization (HUPO) held its inaugural meeting in April in McLean, Virginia, USA. HUPO unites academia and industry to increase the awareness of proteomics and its use for the diagnosis and therapy of diseases. The HUPO advisory council incorporates proteomics experts from North America, Europe and the Far East, hopefully fostering cooperation across the global proteomics community. HUPO will work in close collaboration with its equivalent in the genomics field, HUGO (Human Genome Organization). (http://www.healthtech.com/2001/ hpr/hpr_pressrelease.htm) AP
There is no cure for a failing heart – only the symptoms can be treated. However, a new study provides the exciting prospect of gene therapy to counteract one of the causes of heart failure. Cardiac dysfunction, especially left ventricular dysfunction, is a common occurrence after myocardial infarction. Norepinephrine binds to β-adrenergic receptors on the surface of cardiac myocytes leading to heart muscle contractions. Failing hearts have higher levels of β-adrenergic receptor kinase (βARK). This desensitizes the β-adrenergic receptors and reduces the norepinephrine signaling, reducing contractions. Using catheters to deliver adenoviral vectors expressing a βARK-inhibitory peptide into the heart, researchers at the Duke University Medical Center reversed left ventricular dysfunction after a myocardial infarction in rabbits. This approach could be
http://tig.trends.com 0168–9525/01/$ – see front matter © 2001 Elsevier Science Ltd. All rights reserved.
News & Comment
tested within the next three years in patients with severe heart failure who are waiting for a heart transplant. [Shah, A.S. et al. (2001) Circulation 103, 1311–1316] AP
TRENDS in Genetics Vol.17 No.5 May 2001
Marie-Antoinette’s son identified
In a new twist to the heredity versus environment debate, Richard Leibovitz, director of intellectual property at the genomics company OriGene (Rockville, MD, USA), evokes a Buddhist who believes that human behaviour can be controlled by meditation and who denies the influence of genes. Neurobiologists are unlikely to agree. On his website ‘The Neurobiologists Guide to Buddha’, Leibovitz has created an online encyclopaedia of personality traits, mental disorders and behaviour associated with certain genes. Although many of the associations are still controversial, Leibovitz does a thorough job of reviewing the literature and debate concerning categories such as alcoholism, sexuality, aggression, depression, agreeableness, extroversion and the ability to learn. Based on the information, Leibovitz says, ‘I can easily imagine a type of gene chip for determining personality.’ (http://www.biojuris.com) HD
Marie-Antoinette came to a notorious end, but the fate of her son was a mystery. Now his remains have been identified. Officially, Louis XVII died at the age of ten while he was imprisoned in the Temple of Paris during the revolution. But rumours persisted that he escaped and a substitute died instead. Indeed, several men later claimed to be him. One of the most famous of these, Carl Wilhelm Naundorff, was recently discredited by Els Jehaes and colleagues using DNA analysis. The same researchers have now identified the real Louis XVII. The heart of the boy who died in the Temple was preserved at autopsy and kept as a relic in the Basillique Saint-Denis in Paris. Two independent laboratories isolated mitochondrial DNA from this heart. The D-loop sequence from this sample is identical to that in samples from the hair of Marie-Antoinette and two of her sisters, and from two contemporary maternal relatives of Louis XVII – Queen Anna of Romania and her brother André de Bourbon-Parme. Given a full historical pedigree for the heart and the fact that the Hapsburg mtDNA sequence is unique among a collection of 1700 European sequences, it seems that Louis XVII did indeed die in prison. [Jehaes, E. et al. (2001) Eur. J. Hum. Genet. 9, 185–190] HD
Gene knockouts in Zebrafish
The fickle finger of fate
Scientists at Purdue University have taken the first steps towards making gene knockouts and transgenics with zebrafish. Until now, the only animal where these gene-knockout experiments worked was the mouse. The limiting factor was the incorporation of the genetically modified cells into functional eggs or sperm (germline transmission). Now, Collodi and colleagues use a rainbow trout spleen cell line as feeder cells to grow zebrafish embryo cells in vitro. When these cells are microinjected into host embryos, they populate the germline of 4% of zebrafish, compared with a rate of 5–14% seen in mouse cells. However, zebrafish have large numbers of embryos available for injection and their developmental phase takes only four days, making this a very attractive system with which to determine gene function on a large scale. [Ma, C. et al. (2001) Proc. Natl. Acad. Sci. U. S. A. 98, 2461–2466] AP
Football managers need look no further than the fingers of their prospective players’ hands to judge whether to put them in the team, according to John Manning and Rogan Taylor. They report a significant correlation between the ratio of digit length and footballing prowess after measuring the lengths of the first and fourth digits on the hands of such sporty types as Paul Gascoigne and Alan Shearer. The same ratio in men has also been associated with autism, left-handedness, symphony orchestra membership and homosexuality. The authors propose prenatal levels of testosterone might underlie the correlation. [Manning, J.T. and Taylor, R.P. (2001) Evol. Hum. Behav. 22, 61–69] CH
Buddha and behaviour
The Canadian biotech initiative With the current controversy over food production and the influence of biotechnology
251
on our lives, a positive input is welcome. BIOTECanada represents the biotechnology sector in Canada and is dedicated to promoting a better understanding of the benefits of biotechnology. Its website (http://www.biotech.ca/) discusses how biotechnology affects our food, health and environment, including lists of pharmaceutical products and GM foods approved for use in Canada. Safety issues are also covered, and all sections of the site have useful links to national and international agencies for further information. SG
Terminator: pest control by a biotech insect A novel approach to pest control is being tested in the US. More than 3000 pink bollworm moths containing a gene that makes them fluoresce will be released under screened cages in a government-owned cotton field near Phoenix, Arizona. The pink bollworm moth is perhaps the most destructive pest of cotton crops worldwide. A native of southern Asia, this pest now infests several states in southwestern United States. If this initial trial is successful, another version of the moth, dubbed ‘Terminator’ by farmers, will be released. The Terminator moth is genetically engineered to be sterile but sexually active. The US Agriculture Department’s Animal and Plant Health Inspection Services hope to contain the pest population by competition with the genetically sterilized moths. Irradiation of moths to make them sterile is currently being used in some areas. But, it takes 60 irradiated moths for every wild moth to be effective, whereas only five biotech moths should be sufficient. AP
Helen Dell [email protected] Steven G. Gray [email protected] Cathy Holding [email protected] Norman A. Johnson [email protected] Akhilesh Pandey [email protected]
http://tig.trends.com 0168–9525/01/$ – see front matter © 2001 Elsevier Science Ltd. All rights reserved.
News & Comment
TRENDS in Genetics Vol.17 No.5 May 2001
Fatal embrace: structural basis of caspase inhibition Strict control of programmed cell death (apoptosis) is essential for the homeostasis and survival of multicellular organisms. The unchecked progression of apoptosis can have dire consequences – too much cell death is often associated with the destruction of healthy cells and tissues (as in neurodegenerative disorders and autoimmune disease); conversely, too little cell death is suspected to be partly responsible for the uncontrolled proliferation of cancer cells. Several of the players that are involved in apoptosis have been identified and now the new data are beginning to unravel their intricate interplay. The apoptotic process is dependent on specific cysteine proteases, known as caspases, that both initiate (initiator caspases, e.g. caspase-9) and execute (effector caspases, e.g. caspase-3,-7) the orderly dismantling of apoptotic cells. Opposing this cellular destruction are two classes of cellular apoptotic inhibitors – members of the BCL-2 and ‘Inhibitor of Apoptosis’ (IAP) families. Whereas the BCL-2 proteins can block the mitochondrial branch of apoptosis by preventing the release of cytochrome c, the IAPs block both the mitochondrion- and
receptor-mediated pathways of apoptosis by binding directly to and inhibiting the initiator and effector caspases. Recently, ground-breaking studies have revealed the structural basis for the inhibition of the effector caspases by the prototype of the IAP family, XIAP. Chai et al. and Huang et al. now reveal the crystal structure of caspase-7 complexed with the inhibitory fragment of XIAP, showing that the XIAP peptide binds the catalytic groove of caspase-7, completely filling the active site and thus blocking substrate entry. Riedl et al. find a similar structural arrangement between XIAP and caspase-3, which is not surprising considering that caspase-3 and caspase-7 share 54% sequence identity and have nearly identical backbone structures. Interestingly, the binding of XIAP is antiparallel to the binding of the natural caspase substrates. Nevertheless, the interactions between caspase-3 or -7 and XIAP are very similar to the binding of caspases and their tetrapeptide inhibitor DEVD-CHO. Unexpectedly, however, XIAP binds to caspases-3 and -7 via the short linker region that precedes the BIR2 (baculoviral IAP repeat, named for its homology to baculoviral IAPs) domain – the
BIR2 domain itself was found to be dispensable and could be replaced with an unrelated protein, such as glutathione S-transferase (GST). The BIR2 domain is now proposed to stabilize the interaction between caspase and XIAP. Significantly, the inhibitor of XIAP called Smac/DIABLO can bind to the BIR2 domain. The interaction of Smac/DIABLO with XIAP is proposed to destabilize the XIAP–caspase-3/-7 interaction and thus liberate XIAP from caspase’s embrace and restore caspase activity. The understanding of the interaction between XIAP and effector caspases further advances our knowledge of programmed cell death and its control. More importantly, it sets the stage for the discovery and rational design of novel peptide caspase inhibitors.
‘Genes were easy’ – the launch of the Human Proteome Organization
Gene therapy saves failing hearts
1 Chai, J. et al. (2001) Structural basis of caspase7 inhibition by XIAP. Cell 104, 769–780 2 Huang, Y. et al. (2001) Structural basis of caspase inhibition by XIAP: differential roles of the linker versus the BIR domain. Cell 104, 781–790 3 Riedl, S. et al. (2001) Structural basis for the inhibition of caspase-3 by XIAP. Cell 104, 791–800
Martin Holcik [email protected]
Journal Club
No rat race The relationship between Celera Genomics and the publicly funded sequencing projects has changed. In contrast to their sometimes rancorous race to sequence the human genome, Celera will now share a $58 million grant with the Baylor University Center of the Human Genome Project to sequence the rat genome. Celera will sequence fragments of the rat genome and Baylor will assemble the fragmented sequence. Both sides will make their information available to the public on the NIH database. In addition to its importance in comparative and evolutionary genomic studies, the rat genomic sequence is valuable because the rat has long been a standard model for medical and pharmaceutical testing. Expect a draft sequence of the rat genome in two years. NJ
Under the slogan ‘Genes were easy’, the Human Proteome Organization (HUPO) held its inaugural meeting in April in McLean, Virginia, USA. HUPO unites academia and industry to increase the awareness of proteomics and its use for the diagnosis and therapy of diseases. The HUPO advisory council incorporates proteomics experts from North America, Europe and the Far East, hopefully fostering cooperation across the global proteomics community. HUPO will work in close collaboration with its equivalent in the genomics field, HUGO (Human Genome Organization). (http://www.healthtech.com/2001/ hpr/hpr_pressrelease.htm) AP
There is no cure for a failing heart – only the symptoms can be treated. However, a new study provides the exciting prospect of gene therapy to counteract one of the causes of heart failure. Cardiac dysfunction, especially left ventricular dysfunction, is a common occurrence after myocardial infarction. Norepinephrine binds to β-adrenergic receptors on the surface of cardiac myocytes leading to heart muscle contractions. Failing hearts have higher levels of β-adrenergic receptor kinase (βARK). This desensitizes the β-adrenergic receptors and reduces the norepinephrine signaling, reducing contractions. Using catheters to deliver adenoviral vectors expressing a βARK-inhibitory peptide into the heart, researchers at the Duke University Medical Center reversed left ventricular dysfunction after a myocardial infarction in rabbits. This approach could be
http://tig.trends.com 0168–9525/01/$ – see front matter © 2001 Elsevier Science Ltd. All rights reserved.
News & Comment
tested within the next three years in patients with severe heart failure who are waiting for a heart transplant. [Shah, A.S. et al. (2001) Circulation 103, 1311–1316] AP
TRENDS in Genetics Vol.17 No.5 May 2001
Marie-Antoinette’s son identified
In a new twist to the heredity versus environment debate, Richard Leibovitz, director of intellectual property at the genomics company OriGene (Rockville, MD, USA), evokes a Buddhist who believes that human behaviour can be controlled by meditation and who denies the influence of genes. Neurobiologists are unlikely to agree. On his website ‘The Neurobiologists Guide to Buddha’, Leibovitz has created an online encyclopaedia of personality traits, mental disorders and behaviour associated with certain genes. Although many of the associations are still controversial, Leibovitz does a thorough job of reviewing the literature and debate concerning categories such as alcoholism, sexuality, aggression, depression, agreeableness, extroversion and the ability to learn. Based on the information, Leibovitz says, ‘I can easily imagine a type of gene chip for determining personality.’ (http://www.biojuris.com) HD
Marie-Antoinette came to a notorious end, but the fate of her son was a mystery. Now his remains have been identified. Officially, Louis XVII died at the age of ten while he was imprisoned in the Temple of Paris during the revolution. But rumours persisted that he escaped and a substitute died instead. Indeed, several men later claimed to be him. One of the most famous of these, Carl Wilhelm Naundorff, was recently discredited by Els Jehaes and colleagues using DNA analysis. The same researchers have now identified the real Louis XVII. The heart of the boy who died in the Temple was preserved at autopsy and kept as a relic in the Basillique Saint-Denis in Paris. Two independent laboratories isolated mitochondrial DNA from this heart. The D-loop sequence from this sample is identical to that in samples from the hair of Marie-Antoinette and two of her sisters, and from two contemporary maternal relatives of Louis XVII – Queen Anna of Romania and her brother André de Bourbon-Parme. Given a full historical pedigree for the heart and the fact that the Hapsburg mtDNA sequence is unique among a collection of 1700 European sequences, it seems that Louis XVII did indeed die in prison. [Jehaes, E. et al. (2001) Eur. J. Hum. Genet. 9, 185–190] HD
Gene knockouts in Zebrafish
The fickle finger of fate
Scientists at Purdue University have taken the first steps towards making gene knockouts and transgenics with zebrafish. Until now, the only animal where these gene-knockout experiments worked was the mouse. The limiting factor was the incorporation of the genetically modified cells into functional eggs or sperm (germline transmission). Now, Collodi and colleagues use a rainbow trout spleen cell line as feeder cells to grow zebrafish embryo cells in vitro. When these cells are microinjected into host embryos, they populate the germline of 4% of zebrafish, compared with a rate of 5–14% seen in mouse cells. However, zebrafish have large numbers of embryos available for injection and their developmental phase takes only four days, making this a very attractive system with which to determine gene function on a large scale. [Ma, C. et al. (2001) Proc. Natl. Acad. Sci. U. S. A. 98, 2461–2466] AP
Football managers need look no further than the fingers of their prospective players’ hands to judge whether to put them in the team, according to John Manning and Rogan Taylor. They report a significant correlation between the ratio of digit length and footballing prowess after measuring the lengths of the first and fourth digits on the hands of such sporty types as Paul Gascoigne and Alan Shearer. The same ratio in men has also been associated with autism, left-handedness, symphony orchestra membership and homosexuality. The authors propose prenatal levels of testosterone might underlie the correlation. [Manning, J.T. and Taylor, R.P. (2001) Evol. Hum. Behav. 22, 61–69] CH
Buddha and behaviour
The Canadian biotech initiative With the current controversy over food production and the influence of biotechnology
251
on our lives, a positive input is welcome. BIOTECanada represents the biotechnology sector in Canada and is dedicated to promoting a better understanding of the benefits of biotechnology. Its website (http://www.biotech.ca/) discusses how biotechnology affects our food, health and environment, including lists of pharmaceutical products and GM foods approved for use in Canada. Safety issues are also covered, and all sections of the site have useful links to national and international agencies for further information. SG
Terminator: pest control by a biotech insect A novel approach to pest control is being tested in the US. More than 3000 pink bollworm moths containing a gene that makes them fluoresce will be released under screened cages in a government-owned cotton field near Phoenix, Arizona. The pink bollworm moth is perhaps the most destructive pest of cotton crops worldwide. A native of southern Asia, this pest now infests several states in southwestern United States. If this initial trial is successful, another version of the moth, dubbed ‘Terminator’ by farmers, will be released. The Terminator moth is genetically engineered to be sterile but sexually active. The US Agriculture Department’s Animal and Plant Health Inspection Services hope to contain the pest population by competition with the genetically sterilized moths. Irradiation of moths to make them sterile is currently being used in some areas. But, it takes 60 irradiated moths for every wild moth to be effective, whereas only five biotech moths should be sufficient. AP
Helen Dell [email protected] Steven G. Gray [email protected] Cathy Holding [email protected] Norman A. Johnson [email protected] Akhilesh Pandey [email protected]
http://tig.trends.com 0168–9525/01/$ – see front matter © 2001 Elsevier Science Ltd. All rights reserved.