301
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Pollock JD. Gene expression profiling: methodological challenges, results, and prospects for addiction research. Chem Phys Lipids 2002; 121:241-56. [PMID: 12505704 DOI: 10.1016/s0009-3084(02)00160-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This review describes the current methods used to profile gene expression. These methods include microarrays, spotted arrays, serial analysis of gene expression (SAGE), and massive parallel signature sequencing (MPSS). Methodological and statistical problems in interpreting microarray and spotted array experiments are also discussed. Methods and formats such as minimum information about microarray experiments (MIAME) needed to share gene expression data are described. The last part of the review provides an overview of the application of gene-expression profiling technology to substance abuse research and discusses future directions.
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Affiliation(s)
- Jonathan D Pollock
- Genetics and Molecular Neurobiology Research Branch, National Institute on Drug Abuse, 6001 Executive Blvd, Rockville, MD 20850, USA.
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302
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Gong S, Yang XW, Li C, Heintz N. Highly efficient modification of bacterial artificial chromosomes (BACs) using novel shuttle vectors containing the R6Kgamma origin of replication. Genome Res 2002; 12:1992-8. [PMID: 12466304 PMCID: PMC187570 DOI: 10.1101/gr.476202] [Citation(s) in RCA: 204] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Bacterial artificial chromosome (BAC) mediated transgenesis has proven to be a highly reliable way to obtain accurate transgene expression for in vivo studies of gene expression and function. A rate-limiting step in use of this technology to characterize large numbers of genes has been the process with which BACs can be modified by homologous recombination in Escherichia coli. We report here a highly efficient method for modifying BACs by using a novel set of shuttle vectors that contain the R6Kgamma origin for DNA replication, the E. coli RecA gene for recombination, and the SacB gene for negative selection. These new vectors greatly increased the ease with which one can clone the shuttle vectors, as well as screen for co-integrated and resolved clones. Furthermore, we simplify the shuttle vector cloning to one step by incorporation of a "built-in" resolution cassette for rapid removal of the unwanted vector sequences. This new system has been used to modify a dozen BACs. It is well suited for efficient production of modified BACs for use in a variety of in vivo studies.
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Affiliation(s)
- Shiaoching Gong
- Laboratory of Molecular Biology, The Rockefeller University, New York, New York 10021, USA
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303
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Abstract
Energy homeostasis is controlled by a complex neuroendocrine system consisting of peripheral signals like leptin and central signals, in particular, neuropeptides. Several neuropeptides with anorexigenic (POMC, CART, and CRH) as well as orexigenic (NPY, AgRP, and MCH) actions are involved in this complex (partly redundant) controlling system. Starvation as well as overfeeding lead to changes in expression levels of these neuropeptides, which act downstream of leptin, resulting in a physiological response. In this review the role of several anorexigenic and orexigenic (hypothalamic) neuropeptides on food intake and body weight regulation is summarized.
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Affiliation(s)
- J J G Hillebrand
- Department of Medical Pharmacology, Rudolf Magnus Institute for Neurosciences, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
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304
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Enquist LW. Exploiting circuit-specific spread of pseudorabies virus in the central nervous system: insights to pathogenesis and circuit tracers. J Infect Dis 2002; 186 Suppl 2:S209-14. [PMID: 12424699 DOI: 10.1086/344278] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
The neurotropic alpha-herpesviruses are common mammalian pathogens that invade the peripheral and central nervous system of their hosts. Their ability to invade and spread in the nervous system in a directional manner has been exploited to develop them as neuronal circuit tracers. Tracing viruses spread among synaptically connected neurons and, by assaying brain sections for viral antigen or reporter genes expressed from the viruses, chains of synaptically connected neurons can be visualized. Virulent field strains generally are not good tracers, but some attenuated strains perform well. Live attenuated vaccine strains of pseudorabies virus (PRV), such as PRV Bartha, are among the most popular virus circuit tracers. It may be counterintuitive that attenuation results in improved neural tracing that requires extensive replication and spread in the brain. This report summarizes two lines of experiments directed to resolving this apparent paradox and introduces a new paradigm for tracing viruses.
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Affiliation(s)
- L W Enquist
- Department of Molecular Biology, Princeton University, Princeton, NJ 08540, USA.
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305
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Takeda S, Elefteriou F, Levasseur R, Liu X, Zhao L, Parker KL, Armstrong D, Ducy P, Karsenty G. Leptin regulates bone formation via the sympathetic nervous system. Cell 2002; 111:305-17. [PMID: 12419242 DOI: 10.1016/s0092-8674(02)01049-8] [Citation(s) in RCA: 1142] [Impact Index Per Article: 51.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We previously showed that leptin inhibits bone formation by an undefined mechanism. Here, we show that hypothalamic leptin-dependent antiosteogenic and anorexigenic networks differ, and that the peripheral mediators of leptin antiosteogenic function appear to be neuronal. Neuropeptides mediating leptin anorexigenic function do not affect bone formation. Leptin deficiency results in low sympathetic tone, and genetic or pharmacological ablation of adrenergic signaling leads to a leptin-resistant high bone mass. beta-adrenergic receptors on osteoblasts regulate their proliferation, and a beta-adrenergic agonist decreases bone mass in leptin-deficient and wild-type mice while a beta-adrenergic antagonist increases bone mass in wild-type and ovariectomized mice. None of these manipulations affects body weight. This study demonstrates a leptin-dependent neuronal regulation of bone formation with potential therapeutic implications for osteoporosis.
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Affiliation(s)
- Shu Takeda
- Department of Molecular and Human Genetics, One Baylor Plaza, Houston, TX 77030, USA
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306
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Abstract
Organisms eat not only in a response to signals related to energy balance. Eating also occurs in response to "extrinsic," or environmental, signals, including learned cues. Such cues can modify feeding based on motivational value acquired through association with either rewarding or aversive events. We provide evidence that a specific brain system, involving connections between basolateral amygdala and the lateral hypothalamus, is crucial for allowing learned cues (signals that were paired with food delivery when the animal was hungry) to override satiety and promote eating in sated rats. In an assessment of second-order conditioning, we also found that disconnection of this circuitry had no effect on the ability of a conditioned cue to support new learning. Knowledge about neural systems through which food-associated cues specifically control feeding behavior provides a defined model for the study of learning that may be informative for understanding mechanisms that contribute to eating disorders and more moderate forms of overeating.
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307
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Yoshihara Y. Visualizing selective neural pathways with WGA transgene: combination of neuroanatomy with gene technology. Neurosci Res 2002; 44:133-40. [PMID: 12354628 DOI: 10.1016/s0168-0102(02)00130-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Functional logic employed by the nervous system for information processing resides mainly in the wiring patterns among specific types of neurons. Therefore, detailed knowledge on neuronal networks is essential for understanding a wide range of brain functions. A powerful and long-awaited method for analyzing the neuronal connectivity patterns would be to deliver tracers selectively to specific types of neurons and at the same time to label transsynaptically their axonal target neurons. For this purpose, we took advantage of a unique property of plant lectin, wheat germ agglutinin (WGA), which has been used as a transsynaptic tracer in classical neuroanatomical studies. We developed a novel genetic strategy that employs WGA cDNA as a transgene, for the visualization of selective and functional neural pathways in the nervous system. In this article, I will introduce several examples of neural pathways visualized with the WGA transgene and discuss about its further refinement and applications.
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Affiliation(s)
- Yoshihiro Yoshihara
- Laboratory for Neurobiology of Synapse, RIKEN Brain Science Institute, Hirosawa 2-1, Wako, Saitama 351-0198, Japan.
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308
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Affiliation(s)
- Robert Malenka
- Nancy Pritzker Laboratory, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, CA 94304, USA
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309
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Abstract
Discovery of the leptin receptor and its downstream peptidergic pathways has reconfirmed the crucial role of the hypothalamus in the regulation of food intake and energy balance. Strategically located in the midst of the mammalian neuraxis, the hypothalamus receives at least three distinct types of relevant information via direct or indirect neural connections as well as hormone receptors and substrate sensors bestowed on hypothalamic neurons. First, the medial and to a lesser extent the lateral hypothalamus receive a rich mix of information pertaining to the internal state of relative energy repletion/depletion. Second, specific hypothalamic nuclei receive information about the behavioral state, such as diurnal clock, physical activity-level, reproductive cycle, developmental stage, as well as imminent (e.g. fight and flight) and chronic (e.g. infection) stressors, that can potentially impact on short-term availability of fuels and long-term energy balance. Third, the hypothalamus, particularly its lateral aspects, receives information from areas in the forebrain involved in the acquisition, storage, and retrieval of sensory representations of the external food space and internal food experience, as well as from the executive forebrain involved in behavior selection and initiation. In addition, rich intrahypothalamic connections facilitate further distribution of incoming information to various hypothalamic nuclei. On the other hand, the hypothalamus has widespread neural projections to the same cortical areas it receives inputs, and many hypothalamic neurons are one synapse away from most endocrine systems and from both sympathetic and parasympathetic effector organs involved in the flux, storage, mobilization, and utilization of fuels. It is argued that processing within cortico-limbic areas and communication with hypothalamic areas are particularly important in human food intake control that is more and more guided by cognitive rather than metabolic aspects in the obesigenic environment of affluent societies. A distributed neural network for the control of food intake and energy balance consisting of a central processor and several parallel processing loops is hypothesized. Detailed neurochemical, anatomical, and functional analysis of reciprocal connections of the numerous peptidergic neuron populations in the hypothalamus with extrahypothalamic brain areas will be necessary to better understand what hypothalamus, forebrain, and brainstem tell each other and who is in charge under specific conditions of internal and external nutrient availability.
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Affiliation(s)
- Hans-Rudolf Berthoud
- Neurobiology of Nutrition Laboratory, Pennington Biomedical Research Center, Louisiana State University, 6400 Perkins Road, Baton Rouge, LA 70808, USA.
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310
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311
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Laichalk LL, Hochberg D, Babcock GJ, Freeman RB, Thorley-Lawson DA. The dispersal of mucosal memory B cells: evidence from persistent EBV infection. Immunity 2002; 16:745-54. [PMID: 12049725 DOI: 10.1016/s1074-7613(02)00318-7] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have used latent infection with the human herpesvirus Epstein-Barr virus to track the dispersal of memory B cells from the mucosal lymphoid tissue of Waldeyer's ring (tonsils/adenoids). EBV is evenly distributed between the memory compartments of Waldeyer's ring and the peripheral blood. However, it has an approximately 20-fold higher preference for Waldeyer's ring over the spleen or mesenteric lymph nodes. These observations are consistent with a model whereby the virus preferentially establishes persistent infection within memory B cells from Waldeyer's ring. The virus then colonizes the entire peripheral lymphoid system, at a low level, by trafficking with these memory B cells as they circulate through the body and back to Waldeyer's ring. This pathway may reflect that of normal memory B cells derived from nasopharyngeal and other mucosal lymph nodes.
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Affiliation(s)
- Lauri L Laichalk
- Department of Pathology, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA
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312
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Abstract
As a result of gene sequencing and proteomic efforts, thousands of new genes and proteins are now available as potential drug targets. The milieu of these proteins is complex and interactive; thousands of proteins activate, inhibit, and control each other's actions. The effect of blocking or activating a protein in a cell is far-reaching, and can affect whole, as well as adjacent pathways. This network of pathways is dynamic and a cellular response can change depending on the stimulus. In this section, the identification and role of individual proteins within the context of networked pathways, and the regulation of the activity of these proteins is discussed. Diverse chemical libraries, combinatorial libraries, natural products, as well as unnatural natural products that are derived from combinatorial biology (Chiu [2001] Proc. Natl. Acad. Sci. USA. 98:8548-8553), provide the chemical diversity in the search for new drugs to block new targets. Identifying new compounds that can become drugs is a long, expensive, and arduous task and potential targets must be carefully defined so as not to waste valuable resources. Equally important is the selection of compounds to be future drug candidates. Target selectivity in no way guarantees clinical efficacy, as the compound must meet pharmaceutical requirements, such as solubility, absorption, tissue distribution, and lack of toxicity. Thus matching biological diversity with chemical diversity involves something more than tight interactions, it involves interactions of the compounds with a variety host factors that can modulate its activity.
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Affiliation(s)
- P B Fernandes
- Ricerca, LLC, 7528 Auburn Road, Concord, Ohio 4407, USA.
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313
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Holland PC, Petrovich GD, Gallagher M. The effects of amygdala lesions on conditioned stimulus-potentiated eating in rats. Physiol Behav 2002; 76:117-29. [PMID: 12175595 DOI: 10.1016/s0031-9384(02)00688-1] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Both control rats and rats with neurotoxic lesions of the amygdala central nucleus ate more food during presentations of a conditioned stimulus (CS) previously paired with food than during an unpaired CS. This potentiation occurred regardless of whether the food was presented in its usual place or in a different location. By contrast, rats with neurotoxic lesions of basolateral amygdala showed no evidence for conditioned potentiation of eating. These results are considered in the context of anatomical projections from these amygdalar areas to other brain regions involved in feeding, and the role of amygdala subregions in the acquisition of motivational value in conditioning.
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Affiliation(s)
- Peter C Holland
- Department of Psychological and Brain Sciences, Duke University, Box 90086, Durham, NC 27708-0086, USA.
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314
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Kaspar BK, Erickson D, Schaffer D, Hinh L, Gage FH, Peterson DA. Targeted retrograde gene delivery for neuronal protection. Mol Ther 2002; 5:50-6. [PMID: 11786045 DOI: 10.1006/mthe.2001.0520] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The cellular heterogeneity and complex circuitry of the central nervous system make it difficult to achieve precise delivery of experimental and therapeutic agents. We report here an in vivo retrograde gene delivery strategy to target mature projection neurons using adeno-associated virus, a vector with low toxicity and the capacity for long-term gene expression. Viral delivery to axon terminal fields in the hippocampus and striatum resulted in viral internalization, retrograde transport, and transgene expression in specific projection neurons in entorhinal cortex and substantia nigra. Retrograde delivery of the anti-apoptotic gene Bcl2l (also known as Bcl-xL) protected entorhinal projection neurons from subsequent damage-induced cell death. Given the broad distribution of neurons affected by neurodegenerative diseases, gene delivery to both the terminal fields and the projection neurons through retrograde infection provides for strategic therapeutic intervention at both levels of the neural circuit. This approach may also facilitate experimental studies of defined neural circuits.
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Affiliation(s)
- Brian K Kaspar
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
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315
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Cohen P, Zhao C, Cai X, Montez JM, Rohani SC, Feinstein P, Mombaerts P, Friedman JM. Selective deletion of leptin receptor in neurons leads to obesity. J Clin Invest 2001. [PMID: 11602618 DOI: 10.1172/jci200113914] [Citation(s) in RCA: 401] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Animals with mutations in the leptin receptor (ObR) exhibit an obese phenotype that is indistinguishable from that of leptin deficient ob/ob mice. ObR is expressed in many tissues, including brain, and the relative importance of leptin's effects on central versus peripheral sites has not been resolved. To address this, we generated mice with neuron-specific (ObR(SynI)KO) and hepatocyte-specific (ObR(Alb)KO) disruption of ObR. Among the ObR(SynI)KO mice, the extent of obesity was negatively correlated with the level of ObR in hypothalamus and those animals with the lowest levels of ObR exhibited an obese phenotype. The obese mice with low levels of hypothalamic ObR also show elevated plasma levels of leptin, glucose, insulin, and corticosterone. The hypothalamic levels of agouti-related protein and neuropeptide Y RNA are increased in these mice. These data indicate that leptin has direct effects on neurons and that a significant proportion, or perhaps the majority, of its weight-reducing effects are the result of its actions on brain. To explore possible direct effects of leptin on a peripheral tissue, we also characterized ObR(Alb)KO mice. These mice weigh the same as controls and have no alterations in body composition. Moreover, while db/db mice and ObR(SynI)KO mice have enlarged fatty livers, ObR(Alb)KO mice do not. In summary, these data suggest that the brain is a direct target for the weight-reducing and neuroendocrine effects of leptin and that the liver abnormalities of db/db mice are secondary to defective leptin signaling in the brain.
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Affiliation(s)
- P Cohen
- Laboratory of Molecular Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
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316
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Heintz N. BAC to the future: the use of bac transgenic mice for neuroscience research. Nat Rev Neurosci 2001; 2:861-70. [PMID: 11733793 DOI: 10.1038/35104049] [Citation(s) in RCA: 264] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- N Heintz
- Howard Hughes Medical Institute, Laboratory of Molecular Biology, The Rockefeller University, New York 10021, USA.
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317
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Cohen P, Zhao C, Cai X, Montez JM, Rohani SC, Feinstein P, Mombaerts P, Friedman JM. Selective deletion of leptin receptor in neurons leads to obesity. J Clin Invest 2001; 108:1113-21. [PMID: 11602618 PMCID: PMC209535 DOI: 10.1172/jci13914] [Citation(s) in RCA: 233] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Animals with mutations in the leptin receptor (ObR) exhibit an obese phenotype that is indistinguishable from that of leptin deficient ob/ob mice. ObR is expressed in many tissues, including brain, and the relative importance of leptin's effects on central versus peripheral sites has not been resolved. To address this, we generated mice with neuron-specific (ObR(SynI)KO) and hepatocyte-specific (ObR(Alb)KO) disruption of ObR. Among the ObR(SynI)KO mice, the extent of obesity was negatively correlated with the level of ObR in hypothalamus and those animals with the lowest levels of ObR exhibited an obese phenotype. The obese mice with low levels of hypothalamic ObR also show elevated plasma levels of leptin, glucose, insulin, and corticosterone. The hypothalamic levels of agouti-related protein and neuropeptide Y RNA are increased in these mice. These data indicate that leptin has direct effects on neurons and that a significant proportion, or perhaps the majority, of its weight-reducing effects are the result of its actions on brain. To explore possible direct effects of leptin on a peripheral tissue, we also characterized ObR(Alb)KO mice. These mice weigh the same as controls and have no alterations in body composition. Moreover, while db/db mice and ObR(SynI)KO mice have enlarged fatty livers, ObR(Alb)KO mice do not. In summary, these data suggest that the brain is a direct target for the weight-reducing and neuroendocrine effects of leptin and that the liver abnormalities of db/db mice are secondary to defective leptin signaling in the brain.
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Affiliation(s)
- P Cohen
- Laboratory of Molecular Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
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318
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Horvath TL, Diano S, Sotonyi P, Heiman M, Tschöp M. Minireview: ghrelin and the regulation of energy balance--a hypothalamic perspective. Endocrinology 2001; 142:4163-9. [PMID: 11564668 DOI: 10.1210/endo.142.10.8490] [Citation(s) in RCA: 310] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The recently discovered hormone, ghrelin, has been recognized as an important regulator of GH secretion and energy homeostasis. Orexigenic and adipogenic ghrelin is produced by the stomach, intestine, placenta, pituitary, and possibly in the hypothalamus. The concentration of circulating ghrelin, principally derived from the stomach, is influenced by acute and chronic changes in nutritional state. To date, most studies focused on the role of ghrelin in GH secretion or its function in complementing leptin action to prevent energy deficits. The potential significance of ghrelin in the etiology of obesity and cachexia as well as in the regulation of growth processes is the subject of ongoing discussions. A large quantity of information based on clinical trials and experimental studies with ghrelin and previously available synthetic ghrelin receptor agonists (GH secretagogues) must now be integrated with a rapidly increasing amount of data on the central regulation of metabolism and appetite. In this overview, we summarize recent findings and strategies on the integration of ghrelin into neuroendocrine networks that regulate energy homeostasis.
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Affiliation(s)
- T L Horvath
- Reproductive Neuroscience Unit, Department of Obstetrics and Gynecology, Yale Medical School, New Haven, Connecticut 06520, USA.
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319
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Infectious neuroscience. Nat Rev Neurosci 2001. [DOI: 10.1038/35077542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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