251
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Modeling general proteostasis: proteome balance in health and disease. Curr Opin Cell Biol 2010; 23:126-34. [PMID: 21131189 DOI: 10.1016/j.ceb.2010.11.001] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Revised: 11/07/2010] [Accepted: 11/08/2010] [Indexed: 12/17/2022]
Abstract
Protein function is generated and maintained by the proteostasis network (PN) (Balch et al. (2008) Science, 319:916). The PN is a modular, yet integrated system unique to each cell type that is sensitive to signaling pathways that direct development and aging, and respond to folding stress. Mismanagement of protein folding and function triggered by genetic, epigenetic and environmental causes poses a major challenge to human health and lifespan. Herein, we address the impact of proteostasis defined by the FoldFx model on our understanding of protein folding and function in biology. FoldFx describes how general proteostasis control (GPC) enables the polypeptide chain sequence to achieve functional balance in the context of the cellular proteome. By linking together the chemical and energetic properties of the protein fold with the composition of the PN we discuss the principle of the proteostasis boundary (PB) as a key component of GPC. The curved surface of the PB observed in 3-dimensional space suggests that the polypeptide chain sequence and the PN operate as an evolutionarily conserved functional unit to generate and sustain protein dynamics required for biology. Modeling general proteostasis provides a rational basis for tackling some of the most challenging diseases facing mankind in the 21st century.
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252
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Garrity PA, Goodman MB, Samuel AD, Sengupta P. Running hot and cold: behavioral strategies, neural circuits, and the molecular machinery for thermotaxis in C. elegans and Drosophila. Genes Dev 2010; 24:2365-82. [PMID: 21041406 PMCID: PMC2964747 DOI: 10.1101/gad.1953710] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Like other ectotherms, the roundworm Caenorhabditis elegans and the fruit fly Drosophila melanogaster rely on behavioral strategies to stabilize their body temperature. Both animals use specialized sensory neurons to detect small changes in temperature, and the activity of these thermosensors governs the neural circuits that control migration and accumulation at preferred temperatures. Despite these similarities, the underlying molecular, neuronal, and computational mechanisms responsible for thermotaxis are distinct in these organisms. Here, we discuss the role of thermosensation in the development and survival of C. elegans and Drosophila, and review the behavioral strategies, neuronal circuits, and molecular networks responsible for thermotaxis behavior.
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Affiliation(s)
- Paul A. Garrity
- Department of Biology, Brandeis University, Waltham, Massachusetts 02454, USA
- National Center for Behavioral Genomics, Brandeis University, Waltham, Massachusetts 02454, USA
| | - Miriam B. Goodman
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305, USA
| | - Aravinthan D. Samuel
- Department of Physics and Center for Brain Science, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Piali Sengupta
- Department of Biology, Brandeis University, Waltham, Massachusetts 02454, USA
- National Center for Behavioral Genomics, Brandeis University, Waltham, Massachusetts 02454, USA
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253
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Kikis EA, Gidalevitz T, Morimoto RI. Protein homeostasis in models of aging and age-related conformational disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 694:138-59. [PMID: 20886762 DOI: 10.1007/978-1-4419-7002-2_11] [Citation(s) in RCA: 131] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The stability of the proteome is crucial to the health of the cell, and contributes significantly to the lifespan of the organism. Aging and many age-related diseases have in common the expression of misfolded and damaged proteins. The chronic expression of damaged proteins during disease can have devastating consequences on protein homeostasis (proteostasis), resulting in disruption ofnumerous biological processes. This chapter discusses our current understanding of the various contributors to protein misfolding, and the mechanisms by which misfolding, and accompanied aggregation/toxicity, is accelerated by stress and aging. Invertebrate models have been instrumental in studying the processes related to aggregation and toxicity of disease-associated proteins and how dysregulation ofproteostasis leads to neurodegenerative diseases of aging.
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Affiliation(s)
- Elise A Kikis
- Department of Biochemistry, Molecular Biology and Cell Biology, Rice Institute for Biomedical Research, 2205 Tech Drive, Hogan 2-100, Northwestern University, Evanston, Illinois 60208, USA
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254
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van der Linden AM, Beverly M, Kadener S, Rodriguez J, Wasserman S, Rosbash M, Sengupta P. Genome-wide analysis of light- and temperature-entrained circadian transcripts in Caenorhabditis elegans. PLoS Biol 2010; 8:e1000503. [PMID: 20967231 PMCID: PMC2953524 DOI: 10.1371/journal.pbio.1000503] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Accepted: 08/19/2010] [Indexed: 12/05/2022] Open
Abstract
Transcriptional profiling experiments identify light- and temperature-entrained circadian transcripts in C. elegans. Most organisms have an endogenous circadian clock that is synchronized to environmental signals such as light and temperature. Although circadian rhythms have been described in the nematode Caenorhabditis elegans at the behavioral level, these rhythms appear to be relatively non-robust. Moreover, in contrast to other animal models, no circadian transcriptional rhythms have been identified. Thus, whether this organism contains a bona fide circadian clock remains an open question. Here we use genome-wide expression profiling experiments to identify light- and temperature-entrained oscillating transcripts in C. elegans. These transcripts exhibit rhythmic expression with temperature-compensated 24-h periods. In addition, their expression is sustained under constant conditions, suggesting that they are under circadian regulation. Light and temperature cycles strongly drive gene expression and appear to entrain largely nonoverlapping gene sets. We show that mutations in a cyclic nucleotide-gated channel required for sensory transduction abolish both light- and temperature-entrained gene expression, implying that environmental cues act cell nonautonomously to entrain circadian rhythms. Together, these findings demonstrate circadian-regulated transcriptional rhythms in C. elegans and suggest that further analyses in this organism will provide new information about the evolution and function of this biological clock. Daily (circadian) rhythms in behavior and physiology allow organisms to adapt to periodic cues such as light and temperature associated with the rotation of the earth. Subsets of molecular components of the internal clock that drive these rhythms, as well as effector genes for behavioral outputs, also exhibit rhythmic expression in many organisms. While circadian rhythms in behavior have previously been described in the nematode Caenorhabditis elegans, no transcriptional rhythms or clock genes have been identified, leaving open the question of the nature of the clock in this organism. Here, we identify light- and temperature-entrained cycling genes in C. elegans via genome-wide transcriptional profiling. Transcripts showing circadian regulation (including expression with a 24-h period maintained upon removal of the entraining stimulus) and temperature compensation were identified. Light and temperature appear to entrain independent sets of genes. We also identify large sets of light- or temperature-driven genes. Mutations in a channel gene previously implicated in sensory transduction in a small set of sensory neurons abolish entrainment of gene expression by environmental signals. This work demonstrates the presence of circadian transcriptional rhythms in C. elegans, and provides the foundation for future investigations into the underlying mechanisms.
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Affiliation(s)
- Alexander M van der Linden
- Department of Biology and National Center for Behavioral Genomics, Brandeis University, Waltham, Massachusetts, United States of America
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255
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Akerfelt M, Morimoto RI, Sistonen L. Heat shock factors: integrators of cell stress, development and lifespan. Nat Rev Mol Cell Biol 2010; 11:545-55. [PMID: 20628411 DOI: 10.1038/nrm2938] [Citation(s) in RCA: 971] [Impact Index Per Article: 69.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Heat shock factors (HSFs) are essential for all organisms to survive exposures to acute stress. They are best known as inducible transcriptional regulators of genes encoding molecular chaperones and other stress proteins. Four members of the HSF family are also important for normal development and lifespan-enhancing pathways, and the repertoire of HSF targets has thus expanded well beyond the heat shock genes. These unexpected observations have uncovered complex layers of post-translational regulation of HSFs that integrate the metabolic state of the cell with stress biology, and in doing so control fundamental aspects of the health of the proteome and ageing.
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Affiliation(s)
- Malin Akerfelt
- Department of Biosciences, Abo Akademi University, BioCity, 20520 Turku, Finland
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256
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Tvermoes BE, Boyd WA, Freedman JH. Molecular characterization of numr-1 and numr-2: genes that increase both resistance to metal-induced stress and lifespan in Caenorhabditis elegans. J Cell Sci 2010; 123:2124-34. [PMID: 20501697 DOI: 10.1242/jcs.065433] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
To define the mechanisms involved in the molecular response to the carcinogenic metal cadmium, two novel metal-inducible genes from C. elegans were characterized: numr-1 and numr-2 (nuclear localized metal responsive). numr-1 and numr-2 sequences and cellular patterns of expression are identical, indicating that these are functionally equivalent genes. Constitutive transcription of numr-1 and numr-2 is developmentally regulated and occurs in the intestine, in head and tail neurons, and vulva muscles. Exposure to metals induces numr-1 and numr-2 transcription in pharyngeal and intestinal cells. Other environmental stressors do not affect transcription, indicating that these are metal-specific, stress-responsive genes. NUMR-1 and NUMR-2 target to nuclei and colocalize with HSF-1, suggesting that they may be components of nuclear stress granules. Nematodes overexpressing NUMR-1 and NUMR-2 are resistant to stress and live longer than control animals; likewise reducing expression increases sensitivity to metals and decreases neuromuscular functions. Upstream regulatory regions of both genes contain potential binding sites for DAF-16 and SKN-1, which are components of the insulin-IGF-like signaling pathway. This pathway regulates longevity and stress responses in C. elegans. NUMR-1 and NUMR-2 may function to promote resistance to environmental stressors and longevity, which is mediated by the insulin-IGF-like signaling pathway.
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Affiliation(s)
- Brooke E Tvermoes
- Laboratory of Molecular Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27009, USA
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257
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Poon PC, Kuo TH, Linford NJ, Roman G, Pletcher SD. Carbon dioxide sensing modulates lifespan and physiology in Drosophila. PLoS Biol 2010; 8:e1000356. [PMID: 20422037 PMCID: PMC2857880 DOI: 10.1371/journal.pbio.1000356] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Accepted: 03/08/2010] [Indexed: 01/22/2023] Open
Abstract
For nearly all life forms, perceptual systems provide access to a host of environmental cues, including the availability of food and mates as well as the presence of disease and predators. Presumably, individuals use this information to assess the current and future states of the environment and to enact appropriate developmental, behavioral, and regulatory decisions. Recent work using the nematode worm, Caenorhabditis elegans, and the fruit fly, Drosophila melanogaster, has established that aging is subject to modulation through neurosensory systems and that this regulation is evolutionarily conserved. To date, sensory manipulations shown to impact Drosophila aging have involved general loss of function or manipulation of complex stimuli. We therefore know little about the specific inputs, sensors, or associated neural circuits that affect these life and death decisions. We find that a specialized population of olfactory neurons that express receptor Gr63a (a component of the olfactory receptor for gaseous phase CO(2)) affects fly lifespan and physiology. Gr63a loss of function leads to extended lifespan, increased fat deposition, and enhanced resistance to some (but not all) environmental stresses. Furthermore, we find that the reduced lifespan that accompanies exposure to odors from live yeast is dependent on Gr63a. Together these data implicate a specific sensory cue (CO(2)) and its associated receptor as having the ability to modulate fly lifespan and alter organism stress response and physiology. Because Gr63a is expressed in a well-defined population of neurons, future work may now be directed at dissecting more complex neurosensory and neuroendocrine circuits that modulate aging in Drosophila.
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Affiliation(s)
- Peter C. Poon
- Huffington Center on Aging, Baylor College of Medicine, Houston, Texas, United States of America
| | - Tsung-Han Kuo
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Nancy J. Linford
- Department of Molecular and Integrative Physiology and Geriatrics Center, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Gregg Roman
- Biology and Biochemistry Department, University of Houston, Houston, Texas, United States of America
| | - Scott D. Pletcher
- Huffington Center on Aging, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Integrative Physiology and Geriatrics Center, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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258
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Healy TM, Tymchuk WE, Osborne EJ, Schulte PM. Heat shock response of killifish (Fundulus heteroclitus): candidate gene and heterologous microarray approaches. Physiol Genomics 2010; 41:171-84. [PMID: 20103695 DOI: 10.1152/physiolgenomics.00209.2009] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Northern and southern subspecies of the Atlantic killifish, Fundulus heteroclitus, differ in maximal thermal tolerance. To determine whether these subspecies also differ in their heat shock response (HSR), we exposed 20°C acclimated killifish to a 2 h heat shock at 34°C and examined gene expression in fish from both subspecies during heat shock and recovery using real-time quantitative PCR and a heterologous cDNA microarray designed for salmonid fishes. The heat shock proteins Hsp70-1, hsp27, and hsp30 were upregulated to a greater extent in the high temperature-tolerant southern subspecies than in the less tolerant northern subspecies, whereas hsp70-2 (which showed the largest upregulation of all the heat shock proteins) in both gill and muscle and hsp90α in muscle was upregulated to a greater extent in northern than in southern fish. These data demonstrate that differences in the HSR between subspecies cannot be due to changes in a single global regulator but must occur via gene-specific mechanisms. They also suggest that the role, if any, of hsps in establishing thermal tolerance is complex and varies from gene to gene. Heterologous microarray hybridization provided interpretable gene expression signatures, detecting differential regulation of genes known to be involved in the heat shock response in other species. Under control conditions, a variety of genes were differentially expressed in muscle between subspecies that suggest differences in muscle fiber type and could relate to previously observed differences between subspecies in the thermal sensitivity of swimming performance and metabolism.
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Affiliation(s)
- Timothy M. Healy
- Department of Zoology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Wendy E. Tymchuk
- Department of Zoology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Edward J. Osborne
- Department of Zoology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Patricia M. Schulte
- Department of Zoology, The University of British Columbia, Vancouver, British Columbia, Canada
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259
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A genomewide RNA interference screen for modifiers of aggregates formation by mutant Huntingtin in Drosophila. Genetics 2010; 184:1165-79. [PMID: 20100940 DOI: 10.1534/genetics.109.112516] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Protein aggregates are a common pathological feature of most neurodegenerative diseases (NDs). Understanding their formation and regulation will help clarify their controversial roles in disease pathogenesis. To date, there have been few systematic studies of aggregates formation in Drosophila, a model organism that has been applied extensively in modeling NDs and screening for toxicity modifiers. We generated transgenic fly lines that express enhanced-GFP-tagged mutant Huntingtin (Htt) fragments with different lengths of polyglutamine (polyQ) tract and showed that these Htt mutants develop protein aggregates in a polyQ-length- and age-dependent manner in Drosophila. To identify central regulators of protein aggregation, we further generated stable Drosophila cell lines expressing these Htt mutants and also established a cell-based quantitative assay that allows automated measurement of aggregates within cells. We then performed a genomewide RNA interference screen for regulators of mutant Htt aggregation and isolated 126 genes involved in diverse cellular processes. Interestingly, although our screen focused only on mutant Htt aggregation, several of the identified candidates were known previously as toxicity modifiers of NDs. Moreover, modulating the in vivo activity of hsp110 (CG6603) or tra1, two hits from the screen, affects neurodegeneration in a dose-dependent manner in a Drosophila model of Huntington's disease. Thus, other aggregates regulators isolated in our screen may identify additional genes involved in the protein-folding pathway and neurotoxicity.
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260
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Gidalevitz T, Kikis EA, Morimoto RI. A cellular perspective on conformational disease: the role of genetic background and proteostasis networks. Curr Opin Struct Biol 2010; 20:23-32. [PMID: 20053547 DOI: 10.1016/j.sbi.2009.11.001] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Accepted: 11/27/2009] [Indexed: 12/12/2022]
Abstract
The inherently error-prone nature of protein biosynthesis and turnover leads to a constant flux of destabilized proteins. Genetic mutations in conformational disease-associated proteins, as well as exposure to acute and chronic proteotoxic stresses, further increase the load of misfolded protein on the proteostasis network. During aging, this leads to enhanced instability of the proteome, failure to buffer destabilizing genetic mutations or polymorphisms, and cellular decline. The combination of cell-type-specific differences in the buffering capacity of the proteostasis network and destabilizing polymorphisms in the genetic background may account for some of the cell-type specificity observed in disease, even when the predominant disease-associated protein is widely expressed.
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Affiliation(s)
- Tali Gidalevitz
- Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, IL 60208-3500, USA
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261
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Collapse of proteostasis represents an early molecular event in Caenorhabditis elegans aging. Proc Natl Acad Sci U S A 2009; 106:14914-9. [PMID: 19706382 DOI: 10.1073/pnas.0902882106] [Citation(s) in RCA: 502] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Protein damage contributes prominently to cellular aging. To address whether this occurs at a specific period during aging or accumulates gradually, we monitored the biochemical, cellular, and physiological properties of folding sensors expressed in different tissues of C. elegans. We observed the age-dependent misfolding and loss of function of diverse proteins harboring temperature-sensitive missense mutations in all somatic tissues at the permissive condition. This widespread failure in proteostasis occurs rapidly at an early stage of adulthood, and coincides with a severely reduced activation of the cytoprotective heat shock response and the unfolded protein response. Enhancing stress responsive factors HSF-1 or DAF-16 suppresses misfolding of these metastable folding sensors and restores the ability of the cell to maintain a functional proteome. This suggests that a compromise in the regulation of proteostatic stress responses occurs early in adulthood and tips the balance between the load of damaged proteins and the proteostasis machinery. We propose that the collapse of proteostasis represents an early molecular event of aging that amplifies protein damage in age-associated diseases of protein conformation.
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262
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Powers ET, Morimoto RI, Dillin A, Kelly JW, Balch WE. Biological and chemical approaches to diseases of proteostasis deficiency. Annu Rev Biochem 2009; 78:959-91. [PMID: 19298183 DOI: 10.1146/annurev.biochem.052308.114844] [Citation(s) in RCA: 841] [Impact Index Per Article: 56.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Many diseases appear to be caused by the misregulation of protein maintenance. Such diseases of protein homeostasis, or "proteostasis," include loss-of-function diseases (cystic fibrosis) and gain-of-toxic-function diseases (Alzheimer's, Parkinson's, and Huntington's disease). Proteostasis is maintained by the proteostasis network, which comprises pathways that control protein synthesis, folding, trafficking, aggregation, disaggregation, and degradation. The decreased ability of the proteostasis network to cope with inherited misfolding-prone proteins, aging, and/or metabolic/environmental stress appears to trigger or exacerbate proteostasis diseases. Herein, we review recent evidence supporting the principle that proteostasis is influenced both by an adjustable proteostasis network capacity and protein folding energetics, which together determine the balance between folding efficiency, misfolding, protein degradation, and aggregation. We review how small molecules can enhance proteostasis by binding to and stabilizing specific proteins (pharmacologic chaperones) or by increasing the proteostasis network capacity (proteostasis regulators). We propose that such therapeutic strategies, including combination therapies, represent a new approach for treating a range of diverse human maladies.
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Affiliation(s)
- Evan T Powers
- Departments of Chemistry and Molecular and Experimental Medicine and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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263
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264
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Abstract
Heat-shock proteins (Hsps) are increasingly being implicated in aging phenotypes and control of life span across species. They are targets of the conserved heat-shock factor and insulin/IGF1-like signaling pathways that affect life span and aging phenotypes. Hsps are expressed in tissue-specific and disease-specific patterns during aging, and their level of expression and induction by stress correlates with and, in some instances, predicts life span. In model organisms, Hsps have been shown to increase life span and ameliorate aging-associated proteotoxicity. Finally, Hsps have emerged as key components in regulating aging-related cellular phenotypes, including cell senescence, apoptosis and cancer. The Hsps, therefore, provide a metric of individual stress and aging and are potential targets for interventions in aging and aging-related diseases.
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Affiliation(s)
- John Tower
- Molecular and Computational Biology Program, Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089-2910, USA.
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265
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Swindell WR. Heat shock proteins in long-lived worms and mice with insulin/insulin-like signaling mutations. Aging (Albany NY) 2009; 1:573-7. [PMID: 20157538 PMCID: PMC2806032 DOI: 10.18632/aging.100058] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Accepted: 06/14/2009] [Indexed: 11/25/2022]
Abstract
Heat shock
proteins (HSPs) have proven to be effective tools for extending
invertebrate lifespan, and inC. elegans daf-2 mutants,
longevity resulting from loss of insulin / insulin-like signals is at least
partly dependent upon elevated HSP expression. In mice, inhibition of the
orthologous growth hormone / insulin-like growth factor I (GH / IGF-I)
pathway has similar pro-longevity effects. A recent study, however,
suggests that loss of GH / IGF-I signals in long-lived mice does not
broadly elevate HSP expression, but in fact decreases HSP expression in
many tissue types, such as liver and kidney. The contribution of chaperones
to the longevity of long-lived mice with altered GH / IGF-I signals may therefore
differ from that described in C. elegans daf-2 mutants. This result,
in combination with other recent findings, underscores the possibility that
systemic overexpression of chaperones will have dissimilar effects on
longevity in vertebrate and invertebrate systems.
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Affiliation(s)
- William R Swindell
- University of Michigan, Departments of Pathology and Geriatrics, Ann Arbor MI 48109, USA.
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266
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Lee SJ, Kenyon C. Regulation of the longevity response to temperature by thermosensory neurons in Caenorhabditis elegans. Curr Biol 2009; 19:715-22. [PMID: 19375320 DOI: 10.1016/j.cub.2009.03.041] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2009] [Revised: 03/16/2009] [Accepted: 03/17/2009] [Indexed: 12/16/2022]
Abstract
BACKGROUND Many ectotherms, including C. elegans, have shorter life spans at high temperature than at low temperature. High temperature is generally thought to increase the "rate of living" simply by increasing chemical reaction rates. In this study, we questioned this view and asked whether the temperature dependence of life span is subject to active regulation. RESULTS We show that thermosensory neurons play a regulatory role in the temperature dependence of life span. Surprisingly, inhibiting the function of thermosensory neurons by mutation or laser ablation causes animals to have even shorter life spans at warm temperature. Thermosensory mutations shorten life span by decreasing expression of daf-9, a gene required for the synthesis of ligands that inhibit the DAF-12, a nuclear hormone receptor. The short life span of thermosensory mutants at warm temperature is completely suppressed by a daf-12(-) mutation. CONCLUSIONS Our data suggest that thermosensory neurons affect life span at warm temperature by changing the activity of a steroid-signaling pathway that affects longevity. We propose that this thermosensory system allows C. elegans to reduce the effect that warm temperature would otherwise have on processes that affect aging, something that warm-blooded animals do by controlling temperature itself.
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Affiliation(s)
- Seung-Jae Lee
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
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267
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Jager M, Deechongkit S, Koepf EK, Nguyen H, Gao J, Powers ET, Gruebele M, Kelly JW. Understanding the mechanism of beta-sheet folding from a chemical and biological perspective. Biopolymers 2009; 90:751-8. [PMID: 18844292 DOI: 10.1002/bip.21101] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Perturbing the structure of the Pin1 WW domain, a 34-residue protein comprised of three beta-strands and two intervening loops has provided significant insight into the structural and energetic basis of beta-sheet folding. We will review our current perspective on how structure acquisition is influenced by the sequence, which determines local conformational propensities and mediates the hydrophobic effect, hydrogen bonding, and analogous intramolecular interactions. We have utilized both traditional site-directed mutagenesis and backbone mutagenesis approaches to alter the primary structure of this beta-sheet protein. Traditional site-directed mutagenesis experiments are excellent for altering side-chain structure, whereas amide-to-ester backbone mutagenesis experiments modify backbone-backbone hydrogen bonding capacity. The transition state structure associated with the folding of the Pin1 WW domain features a partially H-bonded, near-native reverse turn secondary structure in loop 1 that has little influence on thermodynamic stability. The thermodynamic stability of the Pin1 WW domain is largely determined by the formation of a small hydrophobic core and by the formation of desolvated backbone-backbone H-bonds enveloped by this hydrophobic core. Loop 1 engineering to the consensus five-residue beta-bulge-turn found in most WW domains or a four-residue beta-turn found in most beta-hairpins accelerates folding substantially relative to the six-residue turn found in the wild type Pin1 WW domain. Furthermore, the more efficient five- and four-residue reverse turns now contribute to the stability of the three-stranded beta-sheet. These insights have allowed the design of Pin1 WW domains that fold at rates that approach the theoretical speed limit of folding.
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Affiliation(s)
- Marcus Jager
- Department of Chemistry, Skaggs Institute of Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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268
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Prahlad V, Morimoto RI. Integrating the stress response: lessons for neurodegenerative diseases from C. elegans. Trends Cell Biol 2009; 19:52-61. [PMID: 19112021 PMCID: PMC4843516 DOI: 10.1016/j.tcb.2008.11.002] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Revised: 11/26/2008] [Accepted: 11/28/2008] [Indexed: 12/21/2022]
Abstract
All cells possess surveillance and homeostatic mechanisms to adjust protein biogenesis to the demands of growth, differentiation, ageing and environmental stress. However, under certain circumstances, these mechanisms fail to adequately respond to proteotoxic imbalances and result in the accumulation of misfolded proteins. In humans, this can lead to neurodegeneration and other protein conformational diseases. To protect itself, the cell employs highly conserved stress responses and chaperone networks to maintain protein-folding homeostasis (proteostasis). Although the regulation of stress responses, such as the heat-shock response, and of proteostasis have been widely considered to be cell autonomous, recent studies using Caenorhabditis elegans have shown that these processes are regulated by neuronal signaling and endocrine pathways and integrated into other functions of the organism. The hierarchical control of the cellular proteostasis machinery affords insight into the organization of stress regulatory networks in multicellular organisms and offers novel targets for the treatment of human protein conformational diseases.
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Affiliation(s)
- Veena Prahlad
- Department of Biochemistry, Molecular Biology and Cell Biology, Rice Institute for Biomedical Research, Northwestern University, Evanston, IL 60208, USA
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269
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Abstract
When the supply of environmental nutrients is limited, multicellular animals can make both physiological and behavioral changes so as to cope with nutrient starvation. Although physiological and behavioral effects of starvation are well known, the mechanisms by which animals sense starvation systemically remain elusive. Furthermore, what constituent of food is sensed and how it modulates starvation response is still poorly understood. In this study, we use a starvation-hypersensitive mutant to identify molecules and mechanisms that modulate starvation signaling. We found that specific amino acids could suppress the starvation-induced death of gpb-2 mutants, and that MGL-1 and MGL-2, Caenorhabditis elegans homologs of metabotropic glutamate receptors, were involved. MGL-1 and MGL-2 acted in AIY and AIB neurons, respectively. Treatment with leucine suppressed starvation-induced stress resistance and life span extension in wild-type worms, and mutation of mgl-1 and mgl-2 abolished these effects of leucine. Taken together, our results suggest that metabotropic glutamate receptor homologs in AIY and AIB neuron may modulate a systemic starvation response, and that C. elegans senses specific amino acids as an anti-hunger signal.
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Affiliation(s)
- Chanhee Kang
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
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270
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Podrabsky JE. NEURONAL CONTROL OF CELLULAR HEAT SHOCK RESPONSE IN NEMATODES. J Exp Biol 2008. [DOI: 10.1242/jeb.011023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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271
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Abstract
This annual review focuses on invertebrate model organisms, which shed light on new mechanisms in aging and provide excellent systems for in-depth analysis. This year, the first quantitative estimate of evolutionary conservation of genetic effects on lifespan has pointed to the key importance of genes involved in protein synthesis, a finding confirmed and extended by experimental work. Work in Caenorhabditis elegans and Drosophila has highlighted the importance of phase 2 detoxification in extension of lifespan by reduced insulin/Igf-like signalling. Thorough characterization of systems for dietary restriction in C. elegans is starting to show differences in the mechanisms by which these interventions extend lifespan and has revealed a requirement for autophagy. The response to heat shock in C. elegans turns out to be systemic, and mediated by sensory neurons, with potentially interesting implications for the response of lifespan to temperature. Work in Escherichia coli and yeast has revealed a role for retention of aggregated proteins in the parent in the rejuvenation of offspring while, as in C. elegans, removal of the germ line in Drosophila turns out to extend lifespan. Aging research has suffered the loss of a great scientific leader, Seymour Benzer, and his trail-blazing work on aging and neurodegeneration is highlighted.
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272
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Wu Y, Cao Z, Klein WL, Luo Y. Heat shock treatment reduces beta amyloid toxicity in vivo by diminishing oligomers. Neurobiol Aging 2008; 31:1055-8. [PMID: 18762355 DOI: 10.1016/j.neurobiolaging.2008.07.013] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2007] [Revised: 07/09/2008] [Accepted: 07/14/2008] [Indexed: 11/28/2022]
Abstract
Heat shock response, mediated by heat shock proteins, is a highly conserved physiological process in multicellular organisms for reestablishment of cellular homeostasis. Expression of heat shock factors and subsequent heat shock protein plays a role in protection against proteotoxicity in invertebrate and vertebrate models. Proteotoxicity due to beta-amyloid peptide (Abeta) oligomerization has been linked to the pathogenesis of Alzheimer's disease. Previously, we demonstrated that progressive paralysis induced by expression of human Abeta(1-42) in transgenic Caenorhabditis elegans was alleviated by Abeta oligomer inhibitors Ginkgo biloba extract and its constituents [Wu, Y., Wu, Z., Butko, P., Christen, Y., Lambert, M.P., Klein, W.L., Link, C.D., Luo, Y., 2006. Amyloid-beta-induced pathological behaviors are suppressed by Ginkgo biloba extract EGb 761 and ginkgolides in transgenic Caenorhabditis elegans. J. Neurosci. 26(50): 13102-13113]. In this study, we apply a protective heat shock to the transgenic C. elegans and demonstrate: (1) a delay in paralysis, (2) increased expression of small heat shock protein HSP16.2, and (3) significant reduction of Abeta oligomers in a heat shock time-dependent manner. These results suggest that transient heat shock lessens Abeta toxicity by diminishing Abeta oligomerization, which provides a link between up regulation of endogenous chaperone proteins and protection against Abeta proteotoxicity in vivo.
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Affiliation(s)
- Yanjue Wu
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, USA
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273
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Flight MH. Beating the heat. Nat Rev Neurosci 2008. [DOI: 10.1038/nrn2419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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