Other Publications (13)
- Genes, Chromosomes & Cancer
- Science (New York, N.Y.)
- BMC Bioinformatics
- Cancer Research
- Age (Dordrecht, Netherlands)
- Biochimica Et Biophysica Acta
- Aging Cell
- The Journals of Gerontology. Series A, Biological Sciences and Medical Sciences
- Current Biology : CB
- PLoS Biology
- Annual Review of Cell and Developmental Biology
- PLoS Genetics
Articles by Nancy J. Linford in JoVE
Measurement of Lifespan in Drosophila melanogaster Nancy J. Linford1, Ceyda Bilgir1, Jennifer Ro2, Scott D. Pletcher1 1Department of Molecular and Integrative Physiology, University of Michigan, 2Cellular and Molecular Biology Program, University of Michigan Drosophila melanogaster is a powerful model organism for exploring the molecular basis of longevity regulation. This protocol will discuss the steps involved in generating a reproducible, population-based measurement of longevity as well as potential pitfalls and how to avoid them.
Other articles by Nancy J. Linford on PubMed
17beta-Estradiol and the Phytoestrogen Genistein Attenuate Neuronal Apoptosis Induced by the Endoplasmic Reticulum Calcium-ATPase Inhibitor Thapsigargin Steroids. Dec, 2002 | Pubmed ID: 12441188 Estrogenic compounds have been shown to protect neurons from a variety of toxic stimuli in vitro and in vivo and depletion of estrogen at menopause has been associated with increased risk of neurodegenerative diseases. Genistein is an isoflavone soy derivative that binds to estrogen receptors with selective estrogen receptor modulator (SERM) properties. Recent FDA recommendations of soy intake for cholesterol reduction have prompted investigation into the potentially estrogenic role of dietary soy phytochemicals in the brain. In this study, we have shown that 50nM genistein significantly reduces neuronal apoptosis in an estrogen receptor-dependent manner. The importance of apoptosis in the brain has been recognized with regard to organization of the developing brain as well as degeneration in response to disease or stroke; however, the effects of estrogenic compounds on neuronal apoptosis have not been thoroughly examined. We developed a model of apoptotic toxicity in primary cortical neurons by using the endoplasmic reticulum (ER) calcium-ATPase inhibitor, thapsigargin, to test potential anti-apoptotic effects of 17beta-estradiol and genistein. Estrogen receptor beta, but not estrogen receptor alpha, was detected in our primary neuron cultures. Thapsigargin-induced apoptosis was confirmed by loss of mitochondrial function, DNA laddering, nuclear condensation and fragmentation, and caspase activation. Both 17beta-estradiol and genistein reduced the number of apoptotic neurons and reduced the number of neurons containing active caspase-3. This effect was blocked by co-addition of ICI 182780. Our results demonstrate that genistein and 17beta-estradiol have comparable anti-apoptotic properties in primary cortical neurons and that these properties are mediated through estrogen receptors.
Chromosomal Instability in Pancreatic Ductal Cells from Patients with Chronic Pancreatitis and Pancreatic Adenocarcinoma Genes, Chromosomes & Cancer. Jun, 2003 | Pubmed ID: 12696069 Pancreatic adenocarcinoma is a disease with high mortality for which chronic pancreatitis confers a markedly increased risk. We hypothesize that chromosome instability and genomic damage occur in pre-neoplastic pancreatic ductal epithelium, and that this damage may be related to oxidative stress. We used dual-color fluorescence in situ hybridization with centromere probes and locus-specific arm probes for chromosome arms 11q, 17p, and 18q to identify genomic instability in cultures of normal-appearing human pancreatic ductal epithelium from normal organ donor controls compared to patients with chronic pancreatitis or pancreatic adenocarcinoma. To examine early pancreatic tumorigenesis, we studied only normal-appearing pancreatic ductal cells adjacent to pancreatitis or carcinoma. We found that, compared to the finding in normal controls, chromosomal abnormalities are present in normal-appearing human pancreatic ductal epithelia obtained from patients with chronic pancreatitis or pancreatic adenocarcinoma. Furthermore, these chromosomal abnormalities could be induced in cultured pancreatic ductal epithelium from normal organ donors by chronic exposure to dilute hydrogen peroxide, suggesting that oxidative stress may contribute to the development of chromosomal instability in the pancreas. These results elucidate a potential mechanism linking chronic pancreatitis to pancreatic cancer and suggest that chromosomal instability may be an early event in the pathogenesis of pancreatic cancer.
Extension of Murine Life Span by Overexpression of Catalase Targeted to Mitochondria Science (New York, N.Y.). Jun, 2005 | Pubmed ID: 15879174 To determine the role of reactive oxygen species in mammalian longevity, we generated transgenic mice that overexpress human catalase localized to the peroxisome, the nucleus, or mitochondria (MCAT). Median and maximum life spans were maximally increased (averages of 5 months and 5.5 months, respectively) in MCAT animals. Cardiac pathology and cataract development were delayed, oxidative damage was reduced, H2O2 production and H2O2-induced aconitase inactivation were attenuated, and the development of mitochondrial deletions was reduced. These results support the free radical theory of aging and reinforce the importance of mitochondria as a source of these radicals.
Evaluation of Methods for Oligonucleotide Array Data Via Quantitative Real-time PCR BMC Bioinformatics. 2006 | Pubmed ID: 16417622 There are currently many different methods for processing and summarizing probe-level data from Affymetrix oligonucleotide arrays. It is of great interest to validate these methods and identify those that are most effective. There is no single best way to do this validation, and a variety of approaches is needed. Moreover, gene expression data are collected to answer a variety of scientific questions, and the same method may not be best for all questions. Only a handful of validation studies have been done so far, most of which rely on spike-in datasets and focus on the question of detecting differential expression. Here we seek methods that excel at estimating relative expression. We evaluate methods by identifying those that give the strongest linear association between expression measurements by array and the "gold-standard" assay. Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) is generally considered the "gold-standard" assay for measuring gene expression by biologists and is often used to confirm findings from microarray data. Here we use qRT-PCR measurements to validate methods for the components of processing oligo array data: background adjustment, normalization, mismatch adjustment, and probeset summary. An advantage of our approach over spike-in studies is that methods are validated on a real dataset that was collected to address a scientific question.
Oxidative Damage and Aging: Spotlight on Mitochondria Cancer Research. Mar, 2006 | Pubmed ID: 16510562 Whereas free radical damage has been proposed as a key component in the tissue degeneration associated with aging, there has been little evidence that free radical damage limits life span in mammals. The current research shows that overexpression of the antioxidant enzyme catalase in mitochondria can extend mouse life span. These results highlight the importance of mitochondrial damage in aging and suggest that when targeted appropriately, boosting antioxidant defenses can increase mammalian life span.
Extension of Mouse Lifespan by Overexpression of Catalase Age (Dordrecht, Netherlands). Jun, 2006 | Pubmed ID: 19943142 The free radical theory of aging was originally proposed 50 years ago, and is arguably the most popular mechanism explaining the aging process. According to this theory, aging results from the progressive decline in organ function due to the damage generated by reactive oxygen species (ROS). These chemical species are a normal part of metabolism, and a group of enzymes exists to protect cells against their toxic effects. One of these species is hydrogen peroxide (H(2)O(2)), which can be degraded by catalase. To determine the role of hydrogen peroxide in aging and its importance in different subcellular compartments, transgenic mice were developed with increased catalase activities localized to the peroxisome (PCAT), nucleus (NCAT), or mitochondrion (MCAT). The largest effect on lifespan was found in MCAT animals, with a 20% increase in median lifespan and a 10% increase in the maximum lifespan. A more modest effect was seen in PCAT animals, and no significant change was found in NCAT animals. Upon further examination of the MCAT mice, it was found that H(2)O(2) production and H(2)O(2)-induced aconitase inactivation were attenuated, oxidative damage and the development of mitochondrial deletions were reduced, and cardiac pathology and cataract development were delayed. These results are consistent with a role of H(2)O(2) in the development of pathology and in the limitation of mouse lifespan. They also demonstrate the importance of mitochondria as a source, and possible target, of ROS.
Neuronal Cell Cycle Re-entry Mediates Alzheimer Disease-type Changes Biochimica Et Biophysica Acta. Apr, 2007 | Pubmed ID: 17095196 Evidence showing the ectopic re-expression of cell cycle-related proteins in specific vulnerable neuronal populations in Alzheimer disease led us to formulate the hypothesis that neurodegeneration, like cancer, is a disease of inappropriate cell cycle control. To test this notion, we used adenoviral-mediated expression of c-myc and ras oncogenes to drive postmitotic primary cortical neurons into the cell cycle. Cell cycle re-entry in neurons was associated with increased DNA content, as determined using BrdU and DAPI, and the re-expression of cyclin B1, a marker for the G2/M phase of the cell cycle. Importantly, we also found that cell cycle re-entry in primary neurons leads to tau phosphorylation and conformational changes similar to that seen in Alzheimer disease. This study establishes that the cell cycle can be instigated in normally quiescent neuronal cells and results in a phenotype that shares features of degenerative neurons in Alzheimer disease. As such, our neuronal cell model may be extremely valuable for the development of novel therapeutic strategies.
Transcriptional Response to Aging and Caloric Restriction in Heart and Adipose Tissue Aging Cell. Oct, 2007 | Pubmed ID: 17874999 Sustained caloric restriction (CR) extends lifespan in animal models but the mechanism and primary tissue target(s) have not been identified. Gene expression changes with aging and CR were examined in both heart and white adipose tissue (WAT) of Fischer 344 (F344) male rats using Affymetrix RAE 230 arrays and validated by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) on 18 genes. As expected, age had a substantial effect on transcription on both tissues, although only 21% of cardiac age-associated genes were also altered in WAT. Gene set enrichment analysis revealed coordinated small magnitude changes in ribosomal, proteasomal, and mitochondrial genes with similarities in aging between heart and WAT. CR had very different effects on these two tissues at the transcriptional level. In heart, very few age-associated expression changes were affected by CR, while in WAT, CR suppressed a substantial subset of the age-associated changes. Genes unaltered by aging but altered by CR were identified in WAT but not heart. Most interestingly, we identified a gene expression signature associated with mammalian target of rapamycin (mTOR) activity that was down-regulated with age but preserved by CR in both WAT and heart. In addition, lipid metabolism genes, particularly those associated with peroxisome proliferator-activated receptor gamma (PPARgamma)-mediated adipogenesis were reduced with age but preserved with CR in WAT. These results highlight tissue-specific differences in the gene expression response to CR and support a role for CR-mediated preservation of mTOR activity and adipogenesis in aging WAT.
Reduction of Age-associated Pathology in Old Mice by Overexpression of Catalase in Mitochondria The Journals of Gerontology. Series A, Biological Sciences and Medical Sciences. Aug, 2008 | Pubmed ID: 18772469 We describe the effects of mitochondrially targeted catalase (MCAT) expression on end-of-life pathology in mice using detailed semiquantitative histopathological evaluation. We previously reported that the median and maximum life spans of MCAT mice were extended relative to those of wild-type littermates. We now report that MCAT expression is associated with reduced malignant nonhematopoietic tumor burden, reduced cardiac lesions, and a trend toward reduced systemic inflammation, with no effect on hematopoietic neoplasia or glomerulonephropathy. Combined disease burden and comorbidity are also reduced, and MCAT expression is not associated with any detrimental clinical effects. The results suggest that oxidative damage is involved in aging of C57BL/6J mice via modulation of a subset of age-associated lesions. Antioxidant interventions targeting mitochondria may therefore be a viable strategy for prevention or postponement of some age-associated diseases. The variability of the MCAT effect across tissues, however, illustrates the importance of developing semiquantitative histopathology for assessment of comorbidity in life-span studies.
Aging: Fruit Flies Break the Chain to a Longer Life Current Biology : CB. Oct, 2009 | Pubmed ID: 19825350 Mitochondria have long had an enigmatic role in the biology of aging. New research in Drosophila reveals an evolutionarily conserved function for the mitochondrial electron transport chain in the modulation of animal lifespan.
Carbon Dioxide Sensing Modulates Lifespan and Physiology in Drosophila PLoS Biology. 2010 | Pubmed ID: 20422037 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.
Sensory Perception and Aging in Model Systems: from the Outside In Annual Review of Cell and Developmental Biology. 2011 | Pubmed ID: 21756108 Sensory systems provide organisms from bacteria to humans with the ability to interact with the world. Numerous senses have evolved that allow animals to detect and decode cues from sources in both their external and internal environments. Recent advances in understanding the central mechanisms by which the brains of simple organisms evaluate different cues and initiate behavioral decisions, coupled with observations that sensory manipulations are capable of altering organismal lifespan, have opened the door for powerful new research into aging. Although direct links between sensory perception and aging have been established only recently, here we discuss these initial discoveries and evaluate the potential for different forms of sensory processing to modulate lifespan across taxa. Harnessing the neurobiology of simple model systems to study the biological impact of sensory experiences will yield insights into the broad influence of sensory perception in mammals and may help uncover new mechanisms of healthy aging.
Re-patterning Sleep Architecture in Drosophila Through Gustatory Perception and Nutritional Quality PLoS Genetics. 2012 | Pubmed ID: 22570630 Organisms perceive changes in their dietary environment and enact a suite of behavioral and metabolic adaptations that can impact motivational behavior, disease resistance, and longevity. However, the precise nature and mechanism of these dietary responses is not known. We have uncovered a novel link between dietary factors and sleep behavior in Drosophila melanogaster. Dietary sugar rapidly altered sleep behavior by modulating the number of sleep episodes during both the light and dark phase of the circadian period, independent of an intact circadian rhythm and without affecting total sleep, latency to sleep, or waking activity. The effect of sugar on sleep episode number was consistent with a change in arousal threshold for waking. Dietary protein had no significant effect on sleep or wakefulness. Gustatory perception of sugar was necessary and sufficient to increase the number of sleep episodes, and this effect was blocked by activation of bitter-sensing neurons. Further addition of sugar to the diet blocked the effects of sweet gustatory perception through a gustatory-independent mechanism. However, gustatory perception was not required for diet-induced fat accumulation, indicating that sleep and energy storage are mechanistically separable. We propose a two-component model where gustatory and metabolic cues interact to regulate sleep architecture in response to the quantity of sugar available from dietary sources. Reduced arousal threshold in response to low dietary availability may have evolved to provide increased responsiveness to cues associated with alternative nutrient-dense feeding sites. These results provide evidence that gustatory perception can alter arousal thresholds for sleep behavior in response to dietary cues and provide a mechanism by which organisms tune their behavior and physiology to environmental cues.