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Papilloma virus: tools and vectors
Literature
Vitamin E: blocking the beginnings of atherosclerosis? Apolipoprotein E-deficient (apoE2/2) mice are a useful model of human atherosclerosis as they develop vascular lesions with many of the histopathological features of the human disease. In this paper1, apoE2/2 mice have been used to demonstrate the functional importance of oxidative stress in the progression of atherosclerosis. The authors focus their attention on isoprostanes (iPs), which are oxidized derivatives of arachidonic acid. iPs were previously shown to accumulate in human atherosclerotic plaques and thus can serve as a reliable indicator of oxidative stress. In apoE2/2 mice, the iP level in urine and plasma gradually increases with age and is always higher than in control mice. This increase in iP levels is apparent even at eight weeks of age, when no anatomi-
Sperm conceive cues in surprising ways The mammalian sperm acrosome reaction (AR) is essential to fertilization. It is initiated in vivo by the zona pellucida of the egg, and is crucial for inhibiting polyspermy (penetration of the egg by more than one sperm). Basic mechanisms underlying sperm–egg recognition thus evolved very early, preceding the evolution of vertebrate brains. As more secrets of sperm–egg interactions reveal themselves, it becomes apparent that during evolution our brains might have borrowed techniques – and chemical messengers – from this fascinating chapter in the story of life. It has been known for some time that AR can be initiated in vitro by certain hormones or neurotransmitters such as progesterone or g-aminobutyric acid (GABA). The new studies present clear evidence that these messengers, known to function in our brains via interaction with specific receptors, also possess surface receptors on human sperm. The study by Ambhaikar and Puri1 demonstrates that progesterone-binding sites are located in the acrosomal region of spermatozoa. Binding studies with 3H-labelled progesterone indicate that while these surface progesterone receptors are structurally homologous with the familiar intracellular progesterone receptor, they differ in terms of ligand specificity.
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MOLECULAR MEDICINE TODAY, JANUARY 1999
cal atherosclerotic lesions can be detected. This is consistent with the hypothesis that lipid oxidation precedes the development of overt atherosclerosis. Addition of vitamin E to the diet of the apoE2/2 mice significantly decreases iP levels in urine and plasma. Remarkably, the progression of aortic atherosclerosis also visibly slows down in the vitamin E-fed apoE2/2 mice, despite persistently high levels of cholesterol. The conclusion of this paper is clear: lipid oxidation plays an important role in the progression of atherosclerosis. Furthermore, if apoE2/2 mice are a faithful approximation to patients with atherosclerosis, consumption of vitamin E could be a great weapon to fight the disease. 1 Pratico, D. et al. (1998) Vitamin E suppresses isoprostane generation in vivo and reduces atherosclerosis in ApoE-deficient mice, Nat. Med. 4, 1189–1192 Eugene Ivanov PhD [email protected]
The study by Jacob et al.2 examines the correlation between the expression of surface progesterone receptors on human sperm and the rate of in vitro fertilization. It reveals that surface progesterone receptors aggregate during AR and fertilization, but this aggregation is less obvious in sperm from individuals with reduced fertility (assessed in vitro). The third study3 demonstrates specific receptors on sperm for GABA, which functions as the major inhibitory neurotransmitter in the brain. Incubation of human sperm with the GABA agonist muscimol increased their motility. Notably, GABA was detected in both human seminal plasma and sperm, indicating that it plays a role in fertilization. Together, these studies open new avenues for better understanding of and treatment for male infertility. 1 Ambhaikar, M. and Puri, C. (1998) Cell surface binding sites for progesterone on human spermatozoa, Mol. Hum. Reprod. 4, 413–421 2 Jacob, A. et al. (1998) Human sperm nonnuclear progesterone receptor expression is a novel marker for fertilization outcome, Mol. Hum. Reprod. 4, 533–542 3 Ritta, M.N. et al. (1998) Occurrence of GABA and GABA receptors in human spermatozoa, Mol. Hum. Reprod. 4, 769–773 David Gurwitz PhD [email protected]
Papilloma virus: tools and vectors Human papillomaviruses (HPVs) are a group of small DNA viruses associated with benign and malignant epithelial cancers of cutaneous or mucosal origin. More than 75 different types of HPV have been isolated, each type exhibiting a particular tropism for certain kinds of epithelia. Particular types of HPVs (HPV16, 18 and a few rarer types – 31, 33 and 45) are suspected to be the causative agents of at least 95% of cervical cancers, the secondmost frequent cancer in women worldwide. The medical importance of these pathogens has driven intensive research efforts: the genetic organization of their genomes is now solved and the functions of their genes are essentially understood. However, other areas of the HPV life cycle are not so well characterized, such as how HPV DNA is packed and unpacked, and how the virions dock onto target cells. This shortfall in understanding is mainly due to the problems associated with propagating HPVs in cell culture and the lack of an in vitro infectivity assay. Such problems are now being addressed by using a molecular quirk of HPV – its ability to self assemble into virus-like particles (VLPs). Expression of the capsid gene L1 in eukaryotic cells yields VLPs and several research groups around the world are now manipulating VLPs in conjunction with other HPV genes to answer encapsidation questions and develop infectivity assays. VLPs also feature in the design of prophylactic vaccines, and reports have indicated that such reagents can elicit effective anti-tumor immunity. Stauffer et al.1 now describe the use of HPV VLPs as tools for probing HPV biology, as well as their potential for interesting biotechnological spinoffs. They show that heterologous DNA can be encapsulated into VLPs merely by the co-expression of the two capsid proteins L1 and L2 in the presence of heterologous DNA. The minor protein L2 is suspected to be involved in the encapsidation process because it becomes attached to plasmid mini-chromosomes. Interestingly, encapsidation is independent of any HPV packaging signals and particles can encapsidate non-HPV sequences such as plasmids of varying size from 5.4 to 7.9 kb. Furthermore, recombinant VLPs carrying plasmids containing the puromycin resistance gene are infectious, as evidenced by the fact that they can confer puromycin resistance to a number of human cell lines. Such VLPs have great potential for delivering genetic material into target cells, as well as providing useful tools to study HPV biology. 1 Stauffer, Y. et al. (1998) Infectious human papillomavirus type 18 pseudovirions, J. Mol. Biol. 283, 529–536 Roger Hewson PhD [email protected]
1357-4310/99/$ - see front matter © 1999 Elsevier Science. All rights reserved.
Vitamin E: blocking the beginnings of atherosclerosis? Apolipoprotein E-deficient (apoE2/2) mice are a useful model of human atherosclerosis as they develop vascular lesions with many of the histopathological features of the human disease. In this paper1, apoE2/2 mice have been used to demonstrate the functional importance of oxidative stress in the progression of atherosclerosis. The authors focus their attention on isoprostanes (iPs), which are oxidized derivatives of arachidonic acid. iPs were previously shown to accumulate in human atherosclerotic plaques and thus can serve as a reliable indicator of oxidative stress. In apoE2/2 mice, the iP level in urine and plasma gradually increases with age and is always higher than in control mice. This increase in iP levels is apparent even at eight weeks of age, when no anatomi-
Sperm conceive cues in surprising ways The mammalian sperm acrosome reaction (AR) is essential to fertilization. It is initiated in vivo by the zona pellucida of the egg, and is crucial for inhibiting polyspermy (penetration of the egg by more than one sperm). Basic mechanisms underlying sperm–egg recognition thus evolved very early, preceding the evolution of vertebrate brains. As more secrets of sperm–egg interactions reveal themselves, it becomes apparent that during evolution our brains might have borrowed techniques – and chemical messengers – from this fascinating chapter in the story of life. It has been known for some time that AR can be initiated in vitro by certain hormones or neurotransmitters such as progesterone or g-aminobutyric acid (GABA). The new studies present clear evidence that these messengers, known to function in our brains via interaction with specific receptors, also possess surface receptors on human sperm. The study by Ambhaikar and Puri1 demonstrates that progesterone-binding sites are located in the acrosomal region of spermatozoa. Binding studies with 3H-labelled progesterone indicate that while these surface progesterone receptors are structurally homologous with the familiar intracellular progesterone receptor, they differ in terms of ligand specificity.
8
MOLECULAR MEDICINE TODAY, JANUARY 1999
cal atherosclerotic lesions can be detected. This is consistent with the hypothesis that lipid oxidation precedes the development of overt atherosclerosis. Addition of vitamin E to the diet of the apoE2/2 mice significantly decreases iP levels in urine and plasma. Remarkably, the progression of aortic atherosclerosis also visibly slows down in the vitamin E-fed apoE2/2 mice, despite persistently high levels of cholesterol. The conclusion of this paper is clear: lipid oxidation plays an important role in the progression of atherosclerosis. Furthermore, if apoE2/2 mice are a faithful approximation to patients with atherosclerosis, consumption of vitamin E could be a great weapon to fight the disease. 1 Pratico, D. et al. (1998) Vitamin E suppresses isoprostane generation in vivo and reduces atherosclerosis in ApoE-deficient mice, Nat. Med. 4, 1189–1192 Eugene Ivanov PhD [email protected]
The study by Jacob et al.2 examines the correlation between the expression of surface progesterone receptors on human sperm and the rate of in vitro fertilization. It reveals that surface progesterone receptors aggregate during AR and fertilization, but this aggregation is less obvious in sperm from individuals with reduced fertility (assessed in vitro). The third study3 demonstrates specific receptors on sperm for GABA, which functions as the major inhibitory neurotransmitter in the brain. Incubation of human sperm with the GABA agonist muscimol increased their motility. Notably, GABA was detected in both human seminal plasma and sperm, indicating that it plays a role in fertilization. Together, these studies open new avenues for better understanding of and treatment for male infertility. 1 Ambhaikar, M. and Puri, C. (1998) Cell surface binding sites for progesterone on human spermatozoa, Mol. Hum. Reprod. 4, 413–421 2 Jacob, A. et al. (1998) Human sperm nonnuclear progesterone receptor expression is a novel marker for fertilization outcome, Mol. Hum. Reprod. 4, 533–542 3 Ritta, M.N. et al. (1998) Occurrence of GABA and GABA receptors in human spermatozoa, Mol. Hum. Reprod. 4, 769–773 David Gurwitz PhD [email protected]
Papilloma virus: tools and vectors Human papillomaviruses (HPVs) are a group of small DNA viruses associated with benign and malignant epithelial cancers of cutaneous or mucosal origin. More than 75 different types of HPV have been isolated, each type exhibiting a particular tropism for certain kinds of epithelia. Particular types of HPVs (HPV16, 18 and a few rarer types – 31, 33 and 45) are suspected to be the causative agents of at least 95% of cervical cancers, the secondmost frequent cancer in women worldwide. The medical importance of these pathogens has driven intensive research efforts: the genetic organization of their genomes is now solved and the functions of their genes are essentially understood. However, other areas of the HPV life cycle are not so well characterized, such as how HPV DNA is packed and unpacked, and how the virions dock onto target cells. This shortfall in understanding is mainly due to the problems associated with propagating HPVs in cell culture and the lack of an in vitro infectivity assay. Such problems are now being addressed by using a molecular quirk of HPV – its ability to self assemble into virus-like particles (VLPs). Expression of the capsid gene L1 in eukaryotic cells yields VLPs and several research groups around the world are now manipulating VLPs in conjunction with other HPV genes to answer encapsidation questions and develop infectivity assays. VLPs also feature in the design of prophylactic vaccines, and reports have indicated that such reagents can elicit effective anti-tumor immunity. Stauffer et al.1 now describe the use of HPV VLPs as tools for probing HPV biology, as well as their potential for interesting biotechnological spinoffs. They show that heterologous DNA can be encapsulated into VLPs merely by the co-expression of the two capsid proteins L1 and L2 in the presence of heterologous DNA. The minor protein L2 is suspected to be involved in the encapsidation process because it becomes attached to plasmid mini-chromosomes. Interestingly, encapsidation is independent of any HPV packaging signals and particles can encapsidate non-HPV sequences such as plasmids of varying size from 5.4 to 7.9 kb. Furthermore, recombinant VLPs carrying plasmids containing the puromycin resistance gene are infectious, as evidenced by the fact that they can confer puromycin resistance to a number of human cell lines. Such VLPs have great potential for delivering genetic material into target cells, as well as providing useful tools to study HPV biology. 1 Stauffer, Y. et al. (1998) Infectious human papillomavirus type 18 pseudovirions, J. Mol. Biol. 283, 529–536 Roger Hewson PhD [email protected]
1357-4310/99/$ - see front matter © 1999 Elsevier Science. All rights reserved.