This work was supported by funding from the DZNE and a Marie Curie International Reintegration Grant (322120 to D.C.D.)

<ol><li>Balch, W. E., Morimoto, R. I., Dillin, A., Kelly, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Adapting+proteostasis+for+disease+intervention%5BTitle%5D)+AND+%22Science%22%5BJournal%5D)">Adapting proteostasis for disease intervention.</a> Science. 319, 916-919 (2008).</li>
<li>David, D. C. <a target="_blank" href="https://www.ncbi.nlm.nih.gov/pubmed/23181070">Aging and the aggregating proteome.</a> Frontiers in genetics. 3, 247(2012).</li>
<li>Hartl, F. U., Bracher, A., Hayer-Hartl, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Molecular+chaperones+in+protein+folding+and+proteostasis%5BTitle%5D)+AND+%22Nature%22%5BJournal%5D)">Molecular chaperones in protein folding and proteostasis.</a> Nature. 475, 324-332 (2011).</li>
<li>Ayyadevara, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Age-+and+Hypertension-Associated+Protein+Aggregates+in+Mouse+Heart+Have+Similar+Proteomic+Profiles%5BTitle%5D)+AND+%22Hypertension%22%5BJournal%5D)">Age- and Hypertension-Associated Protein Aggregates in Mouse Heart Have Similar Proteomic Profiles.</a> Hypertension. 67, 1006-1013 (2016).</li>
<li>David, D. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Widespread+protein+aggregation+as+an+inherent+part+of+aging+in+C.+elegans%5BTitle%5D)+AND+%22PLoS+biology%22%5BJournal%5D)">Widespread protein aggregation as an inherent part of aging in C. elegans.</a> PLoS biology. 8, 1000450(2010).</li>
<li>Demontis, F., Perrimon, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((FOXO%2F4E-BP+signaling+in+Drosophila+muscles+regulates+organism-wide+proteostasis+during+aging%5BTitle%5D)+AND+%22Cell%22%5BJournal%5D)">FOXO/4E-BP signaling in Drosophila muscles regulates organism-wide proteostasis during aging.</a> Cell. 143, 813-825 (2010).</li>
<li>Lechler, M. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Reduced+Insulin%2FIGF-1+Signaling+Restores+the+Dynamic+Properties+of+Key+Stress+Granule+Proteins+during+Aging%5BTitle%5D)+AND+%22Cell+reports%22%5BJournal%5D)">Reduced Insulin/IGF-1 Signaling Restores the Dynamic Properties of Key Stress Granule Proteins during Aging.</a> Cell reports. 18, 454-467 (2017).</li>
<li>Reis-Rodrigues, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Proteomic+analysis+of+age-dependent+changes+in+protein+solubility+identifies+genes+that+modulate+lifespan%5BTitle%5D)+AND+%22Aging+cell%22%5BJournal%5D)">Proteomic analysis of age-dependent changes in protein solubility identifies genes that modulate lifespan.</a> Aging cell. 11, 120-127 (2012).</li>
<li>Tanase, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Role+of+Carbonyl+Modifications+on+Aging-Associated+Protein+Aggregation%5BTitle%5D)+AND+%22Scientific+reports%22%5BJournal%5D)">Role of Carbonyl Modifications on Aging-Associated Protein Aggregation.</a> Scientific reports. 6, 19311(2016).</li>
<li>Walther, D. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Widespread+Proteome+Remodeling+and+Aggregation+in+Aging+C.+elegans%5BTitle%5D)+AND+%22Cell%22%5BJournal%5D)">Widespread Proteome Remodeling and Aggregation in Aging C. elegans.</a> Cell. 161, 919-932 (2015).</li>
<li>Lee, V. M., Wang, J., Trojanowski, J. Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Purification+of+paired+helical+filament+tau+and+normal+tau+from+human+brain+tissue%5BTitle%5D)+AND+%22Methods+in+enzymology%22%5BJournal%5D)">Purification of paired helical filament tau and normal tau from human brain tissue.</a> Methods in enzymology. 309, 81-89 (1999).</li>
<li>Goudeau, J., Aguilaniu, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Carbonylated+proteins+are+eliminated+during+reproduction+in+C.+elegans%5BTitle%5D)+AND+%22Aging+cell%22%5BJournal%5D)">Carbonylated proteins are eliminated during reproduction in C. elegans.</a> Aging cell. 9, 991-1003 (2010).</li>
<li>Zimmerman, S. M., Hinkson, I. V., Elias, J. E., Kim, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Reproductive+Aging+Drives+Protein+Accumulation+in+the+Uterus+and+Limits+Lifespan+in+C.+elegans%5BTitle%5D)+AND+%22PLoS+genetics%22%5BJournal%5D)">Reproductive Aging Drives Protein Accumulation in the Uterus and Limits Lifespan in C. elegans.</a> PLoS genetics. 11, 1005725(2015).</li>
<li>Uno, M., Nishida, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Lifespan-regulating+genes+in+C.+elegans%5BTitle%5D)+AND+%22Npj+Aging+And+Mechanisms+Of+Disease%22%5BJournal%5D)">Lifespan-regulating genes in C. elegans.</a> Npj Aging And Mechanisms Of Disease. 2, 16010(2016).</li>
<li>Sulston, J. H. <a target="_blank" href="NULL">The Nematode Caenorhabditis elegans</a>. , Cold Spring Harbor Laboratory Press. 587-606 (1988).</li>
<li>Maine, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((RNAi+As+a+tool+for+understanding+germline+development+in+Caenorhabditis+elegans%3A+uses+and+cautions%5BTitle%5D)+AND+%22Developmental+biology%22%5BJournal%5D)">RNAi As a tool for understanding germline development in Caenorhabditis elegans: uses and cautions.</a> Developmental biology. 239, 177-189 (2001).</li>
<li>Rauniyar, N., Yates, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Isobaric+labeling-based+relative+quantification+in+shotgun+proteomics%5BTitle%5D)+AND+%22Journal+of+proteome+research%22%5BJournal%5D)">Isobaric labeling-based relative quantification in shotgun proteomics.</a> Journal of proteome research. 13, 5293-5309 (2014).</li>
<li>Brignull, H. R., Morley, J. F., Garcia, S. M., Morimoto, R. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Modeling+polyglutamine+pathogenesis+in+C.+elegans%5BTitle%5D)+AND+%22Methods+in+enzymology%22%5BJournal%5D)">Modeling polyglutamine pathogenesis in C. elegans.</a> Methods in enzymology. 412, 256-282 (2006).</li>
<li>Fay, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Classical+genetic+methods%5BTitle%5D)+AND+%22WormBook%22%5BJournal%5D)">Classical genetic methods.</a> WormBook. , 1-58 (2013).</li>
<li>Brunquell, J., Bowers, P., Westerheide, S. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Fluorodeoxyuridine+enhances+the+heat+shock+response+and+decreases+polyglutamine+aggregation+in+an+HSF-1-dependent+manner+in+Caenorhabditis+elegans%5BTitle%5D)+AND+%22Mech+Ageing+Dev%22%5BJournal%5D)">Fluorodeoxyuridine enhances the heat shock response and decreases polyglutamine aggregation in an HSF-1-dependent manner in Caenorhabditis elegans.</a> Mech Ageing Dev. 141, 1-4 (2014).</li>
<li>Angeli, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+DNA+synthesis+inhibitor+is+protective+against+proteotoxic+stressors+via+modulation+of+fertility+pathways+in+Caenorhabditis+elegans%5BTitle%5D)+AND+%22Aging+%28Albany+NY%29%22%5BJournal%5D)">A DNA synthesis inhibitor is protective against proteotoxic stressors via modulation of fertility pathways in Caenorhabditis elegans.</a> Aging (Albany NY). 5, 759-769 (2013).</li>
<li>Feldman, N., Kosolapov, L., Ben-Zvi, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Fluorodeoxyuridine+improves+Caenorhabditis+elegans+proteostasis+independent+of+reproduction+onset%5BTitle%5D)+AND+%22PLoS+One%22%5BJournal%5D)">Fluorodeoxyuridine improves Caenorhabditis elegans proteostasis independent of reproduction onset.</a> PLoS One. 9, 85964(2014).</li>
<li>Davies, S. K., Leroi, A. M., Bundy, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Fluorodeoxyuridine+affects+the+identification+of+metabolic+responses+to+daf-2+status+in+Caenorhabditis+elegans%5BTitle%5D)+AND+%22Mech+Ageing+Dev%22%5BJournal%5D)">Fluorodeoxyuridine affects the identification of metabolic responses to daf-2 status in Caenorhabditis elegans.</a> Mech Ageing Dev. 133, 46-49 (2012).</li>
<li>Luo, S., Kleemann, G. A., Ashraf, J. M., Shaw, W. M., Murphy, C. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((TGF-beta+and+insulin+signaling+regulate+reproductive+aging+via+oocyte+and+germline+quality+maintenance%5BTitle%5D)+AND+%22Cell%22%5BJournal%5D)">TGF-beta and insulin signaling regulate reproductive aging via oocyte and germline quality maintenance.</a> Cell. 143, 299-312 (2010).</li>
<li>Andux, S., Ellis, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Apoptosis+maintains+oocyte+quality+in+aging+Caenorhabditis+elegans+females%5BTitle%5D)+AND+%22PLoS+genetics%22%5BJournal%5D)">Apoptosis maintains oocyte quality in aging Caenorhabditis elegans females.</a> PLoS genetics. 4, 1000295(2008).</li>
<li>Vilchez, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((RPN-6+determines+C.+elegans+longevity+under+proteotoxic+stress+conditions%5BTitle%5D)+AND+%22Nature%22%5BJournal%5D)">RPN-6 determines C. elegans longevity under proteotoxic stress conditions.</a> Nature. 489, 263-268 (2012).</li>
<li>Ghazi, A., Henis-Korenblit, S., Kenyon, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+transcription+elongation+factor+that+links+signals+from+the+reproductive+system+to+lifespan+extension+in+Caenorhabditis+elegans%5BTitle%5D)+AND+%22PLoS+genetics%22%5BJournal%5D)">A transcription elongation factor that links signals from the reproductive system to lifespan extension in Caenorhabditis elegans.</a> PLoS genetics. 5, 1000639(2009).</li>
<li>Shemesh, N., Shai, N., Meshnik, L., Katalan, R., Ben-Zvi, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Uncoupling+the+Trade-Off+between+Somatic+Proteostasis+and+Reproduction+in+Caenorhabditis+elegans+Models+of+Polyglutamine+Diseases%5BTitle%5D)+AND+%22Front+Mol+Neurosci%22%5BJournal%5D)">Uncoupling the Trade-Off between Somatic Proteostasis and Reproduction in Caenorhabditis elegans Models of Polyglutamine Diseases.</a> Front Mol Neurosci. 10, 101(2017).</li>
<li>Kaletsky, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+C.+elegans+adult+neuronal+IIS%2FFOXO+transcriptome+reveals+adult+phenotype+regulators%5BTitle%5D)+AND+%22Nature%22%5BJournal%5D)">The C. elegans adult neuronal IIS/FOXO transcriptome reveals adult phenotype regulators.</a> Nature. 529, 92-96 (2016).</li>
<li>Kawarabayashi, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Age-dependent+changes+in+brain%2C+CSF%2C+and+plasma+amyloid+%28beta%29+protein+in+the+Tg2576+transgenic+mouse+model+of+Alzheimer%27s+disease%5BTitle%5D)+AND+%22The+Journal+of+neuroscience+%3A+the+official+journal+of+the+Society+for+Neuroscience%22%5BJournal%5D)">Age-dependent changes in brain, CSF, and plasma amyloid (beta) protein in the Tg2576 transgenic mouse model of Alzheimer's disease.</a> The Journal of neuroscience : the official journal of the Society for Neuroscience. 21, 372-381 (2001).</li>
<li>Kraemer, B. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Neurodegeneration+and+defective+neurotransmission+in+a+Caenorhabditis+elegans+model+of+tauopathy%5BTitle%5D)+AND+%22Proceedings+of+the+National+Academy+of+Sciences+of+the+United+States+of+America%22%5BJournal%5D)">Neurodegeneration and defective neurotransmission in a Caenorhabditis elegans model of tauopathy.</a> Proceedings of the National Academy of Sciences of the United States of America. 100, 9980-9985 (2003).</li>
</ol>

The authors have nothing to disclose.

Here we report a methodology to isolate highly-insoluble protein aggregates from aging C. elegans subjected to RNAi for analysis by mass spectrometry and Western blotting. We show that improving proteostasis by reducing IIS greatly prevents age-dependent protein aggregation. By selecting specific aggregation-prone proteins to overexpress in C. elegans, it is possible to dissect further the mechanisms modulating inherent protein aggregation.
Inherent Age-dependent Prot...

Protein misfolding and aggregation are recognized as a hallmark of several neurodegenerative diseases such as AD, PD, amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and many others. For instance, &#945;-synuclein assemblies into amyloid fibrils that accumulate as Lewy bodies particularly in the substantia nigra of PD patients, while in ALS patients TDP-43 or FUS misfold to form cytoplasmic aggregates in degenerating motor neurons. In each of these neurodegenerative disorders, mechanisms maintaining protein homeostasis or proteostasis fail to prevent the accumulation of misfolded proteins, consequently leading to disease.
Proteostasis is critical to ensure cellular functions and under normal conditions these regulatory mechanisms tightly control the rate of protein synthesis, folding, and degradation. Several studies demonstrate that with ageing, the ability of many cells and organs to preserve protein homeostasis is gradually compromised and the physiological deterioration of the proteostasis networks with age is an important aggravating factor for neurodegenerative diseases (reviewed in references1,2,3). The fact that the protein quality control and the cellular response to unfolded protein stress are compromised with age suggests that protein misfolding and aggregation could be a general consequence of aging. Indeed, we and others have demonstrated that protein aggregation is not restricted to disease and instead part of the proteome becomes highly detergent-insoluble in aged animals4,5,6,7,8,9,10. Computational and in vivo analysis revealed that these physiological age-related aggregates resemble disease aggregates in several aspects5. The discovery of endogenous, age-dependent protein aggregation gives us the opportunity to dissect the molecular and cellular mechanisms that regulate protein aggregation, without using ectopically expressed human disease-associated proteins. At present, only limited information exists about the regulation of widespread protein insolubility and about the effects of this dysregulation on the health of the organism.
The nematode C. elegans is one of the most extensively studied model organisms in aging research as these animals have a relatively short lifespan and show many characteristic aging features observed in higher organisms. The effects of aging on protein insolubility have been studied in C. elegans by sequential biochemical fractionation based on differential solubility, which is widely used to extract disease aggregates in the field of neurodegeneration research11. By quantitative mass spectrometry, several hundred proteins were shown to become aggregation-prone in C. elegans in the absence of disease5. Here we describe in detail the protocol to grow large numbers of worms in liquid culture and the sequential extraction to isolate aggregated proteins for quantification by mass spectrometry and analysis by Western blot. Because misfolded and aggregation-prone proteins accumulate in aged C. elegans gonads and masks changes in other somatic tissues5,12,13, we use a gonad-less mutant to focus the analysis on protein insolubility in non-reproductive tissues. The method presented enables the analysis of highly-insoluble, large aggregates that are insoluble in 0.5% SDS and pelleted by relatively low centrifugal speed. Alternatively, a less stringent extraction protocol to collect also smaller and more soluble aggregates has been published elsewhere10. In addition, we describe the method used to assess aggregation in vivo in C. elegans.
Overall, these methods in combination with RNA interference (RNAi) can evaluate the role of a gene of interest in modulating age-dependent protein aggregation. For this we describe the analysis of extracts from young and aged worms with and without knockdown of a specific protein of interest using RNAi. These methods should be a powerful tool to determine which components of the proteostasis network regulate protein insolubility. Several interventions such as reduced insulin/insulin-like growth factor (IGF) 1 signaling (IIS) have been shown to dramatically delay C. elegans aging14. Longevity pathways often induce protein-quality control mechanisms and thus these pathways could be actively influencing the rate of protein aggregation. As an example, we demonstrate reduced inherent protein aggregation in long-lived animals upon inhibition of the IIS pathway7.

<table><tbody><tr><td>Fernbach culture flask&amp;nbsp;</td><td>Corning</td><td>4425-2XL</td><td>Pyrex, Capacity 2,800 ml, with 3 baffle indents</td></tr><tr><td>Membrane Screw Cap&amp;nbsp;</td><td>Schott</td><td>1088655</td><td>GL45</td></tr><tr><td>Nutating Mixer</td><td>VWR</td><td>444-0148</td><td></td></tr><tr><td>Separatory funnel</td><td>Nalgene</td><td>4300-1000</td><td>Capacity 1,000 ml</td></tr><tr><td>1 ml syringe&amp;nbsp;</td><td>BD Plastipak</td><td>300013</td><td></td></tr><tr><td>Gray needle, 27 G x &amp;frac12; &quot;, 0.4 mm x 13 mm</td><td>BD Microlance 3</td><td>300635</td><td></td></tr><tr><td>Membrane filters 0.025 &amp;micro;M</td><td>Millipore</td><td>VSWP04700</td><td></td></tr><tr><td>pH strip</td><td>Machery-Nagel</td><td>92110</td><td>pH-Fix 0-14</td></tr><tr><td>Protease Inhibitor Cocktail</td><td>Roche</td><td>4693132001</td><td>Complete Mini EDTA-free tablets&amp;nbsp;</td></tr><tr><td>Octoxynol-9&amp;nbsp;</td><td>Applichem</td><td>A1388</td><td>Triton X-100</td></tr><tr><td>4-Morpholineethanesulfonic acid (MES)</td><td>Sigma-Aldrich</td><td>M1317</td><td></td></tr><tr><td>Nonylphenylpolyethylenglycol</td><td>Applichem</td><td>A1694</td><td>Nonidet P40 (NP40)</td></tr><tr><td>DNaseI</td><td>Roche</td><td>04716728001</td><td>recombinant, RNase free</td></tr><tr><td>RNaseA</td><td>Promega</td><td>A7973</td><td>solution</td></tr><tr><td>Total protein blot staining</td><td>Thermofisher</td><td>S11791</td><td>Sypro Ruby protein blot stain</td></tr><tr><td>Total protein gel staining</td><td>Thermofisher</td><td>S12001</td><td>Sypro Ruby protein gel stain</td></tr><tr><td>TCEP (tris (2-carboxyethyl) phosphine hydrochloride)</td><td>Serva</td><td>36970</td><td></td></tr><tr><td>Iodoacetamide</td><td>Serva</td><td>26710</td><td></td></tr><tr><td>Ammoniumbicarbonate</td><td>Sigma-Aldrich</td><td>09830</td><td></td></tr><tr><td>Sequencing Grade Modified Trypsin</td><td>Promega</td><td>V5111</td><td></td></tr><tr><td>Isobaric tags for relative and absolute quantitation</td><td>Sciex</td><td>4352135</td><td>iTRAQ Reagents Multiplex Kit</td></tr><tr><td>Centrifuge Avanti J-26XP</td><td>Beckmann Coulter</td><td>393126</td><td></td></tr><tr><td>Ultracentrifuge Optima Max-XP</td><td>Beckmann Coulter</td><td>393315</td><td></td></tr><tr><td>Centrifuge 5424R</td><td>Eppendorf</td><td>5404000413</td><td></td></tr><tr><td>Centrifuge 5702</td><td>Eppendorf</td><td>5702000329</td><td></td></tr><tr><td>Centrifuge Megafuge 40R</td><td>Thermo Scientific</td><td>75004518</td><td></td></tr><tr><td>Concentrator Plus</td><td>Eppendorf</td><td>5305000304</td><td>Centrifugal evaporator</td></tr><tr><td>Fluorescent stereo-microscope M165 FC&amp;nbsp;</td><td>Leica</td><td></td><td>With Planapo 2.0x objective</td></tr><tr><td>Dissection microscope</td><td>Leica&amp;nbsp;</td><td></td><td>Leica S6E</td></tr><tr><td>High magnification microscope Zeiss Axio Observer Z1</td><td>Zeiss</td><td></td><td>With PlanAPOCHROMAT 20x objective and Zeiss Axio Cam MRm</td></tr><tr><td>&lt;strong&gt;Software&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Image analysis software</td><td>ImageJ</td><td></td><td></td></tr><tr><td>Analysis of mass spectrometry data</td><td>Protein Prospector</td><td></td><td>http://prospector.ucsf.edu/prospector/mshome.htm</td></tr><tr><td>&lt;strong&gt;E.coli strain&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>OP50</td><td>CGC</td><td></td><td></td></tr><tr><td>&lt;strong&gt;RNAi bacteria&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>L4440</td><td>Julie Ahringer RNAi library</td><td></td><td></td></tr><tr><td>&lt;strong&gt;&lt;em&gt;C. elegans&lt;/em&gt; mutants&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>CF2253</td><td>CGC, strain name: EJ1158&amp;nbsp;</td><td></td><td>Genotype: &lt;em&gt;gon-2(q388)&lt;/em&gt;</td></tr><tr><td>&lt;strong&gt;&lt;em&gt;C. elegans&lt;/em&gt; transgenics&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>DCD214</td><td>Della David&#039;s lab at DZNE T&amp;uuml;bingen</td><td></td><td>Genotype: &lt;em&gt;N2; uqIs24[Pmyo-2::tagrfp::pab-1]&lt;/em&gt;</td></tr><tr><td>DCD215</td><td>Della David&#039;s lab at DZNE T&amp;uuml;bingen</td><td></td><td>Genotype: &lt;em&gt;daf-2(e1370) III; uqIs24[Pmyo-2::tagrfp::pab-1]&lt;/em&gt;</td></tr></tbody></table>

methods to study changes in inherent protein aggregation with age in caenorhabditis elegans

In the last decades, the prevalence of neurodegenerative disorders, such as Alzheimer's disease (AD) and Parkinson's disease (PD), has grown. These age-associated disorders are characterized by the appearance of protein aggregates with fibrillary structure in the brains of these patients. Exactly why normally soluble proteins undergo an aggregation process remains poorly understood. The discovery that protein aggregation is not limited to disease processes and instead part of the normal aging process enables the study of the molecular and cellular mechanisms that regulate protein aggregation, without using ectopically expressed human disease-associated proteins. Here we describe methodologies to examine inherent protein aggregation in Caenorhabditis elegans through complementary approaches. First, we examine how to grow large numbers of age-synchronized C. elegans to obtain aged animals and we present the biochemical procedures to isolate highly-insoluble-large aggregates. In combination with a targeted genetic knockdown, it is possible to dissect the role of a gene of interest in promoting or preventing age-dependent protein aggregation by using either a comprehensive analysis with quantitative mass spectrometry or a candidate-based analysis with antibodies. These findings are then confirmed by in vivo analysis with transgenic animals expressing fluorescent-tagged aggregation-prone proteins. These methods should help clarify why certain proteins are prone to aggregate with age and ultimately how to keep these proteins fully functional.

We used the methods presented here to evaluate how long-lived animals with reduced IIS modulate age-dependent protein aggregation. By Western blot (see step 2.2, Quick insoluble protein extraction for Western blot analysis), we analyzed the total and the insoluble protein content of young (day 3 of adulthood) and aged (day 18 of adulthood) worms on control RNAi and on RNAi targeting the insulin/IGF-1-like receptor daf-2. We observed no large changes in total protein levels with a...

Watch this Scientific Journal Video about Methods to Study Changes in Inherent Protein Aggregation with Age in Caenorhabditis elegans at JoVE.com

Methods to Study Changes in Inherent Protein Aggregation with Age in Caenorhabditis elegans

The goal of the method presented here is to explore protein aggregation during normal aging in the model organism C. elegans. The protocol represents a powerful tool to study the highly insoluble large aggregates that form with age and to determine how changes in proteostasis impact protein aggregation.

Methods to Study Changes in Inherent Protein Aggregation with Age in Caenorhabditis elegans

In the last decades, the prevalence of neurodegenerative disorders, such as Alzheimer's disease (AD) and Parkinson's disease (PD), has grown. These ...

methods-to-study-changes-inherent-protein-aggregation-with-age

Research

JoVE Journal

Biology

8.5K Views.  German Center for Neurodegenerative Diseases (DZNE). The goal of the method presented here is to explore protein aggregation during normal aging in the model organism C. elegans. The protocol represents a powerful tool to study the highly insoluble large aggregates that form with age and to determine how changes in proteostasis impact protein aggregation.

Video: Methods to Study Changes in Inherent Protein Aggregation with Age in Caenorhabditis elegans

Characterization of Amyloid Structures in Aging C. Elegans Using Fluorescence Lifetime Imaging

Amyloid fibrils are associated with a number of neurodegenerative diseases such as Huntington&#39;s, Parkinson&#39;s, or Alzheimer&#39;s disease. These amyloid fibrils can sequester endogenous metastable proteins as well as components of the proteostasis network (PN) and thereby exacerbate protein misfolding in the cell. There are a limited number of tools available to assess the aggregation process of amyloid proteins within an animal. We present a protocol for fluorescence lifetime microscopy (FLIM) that allows monitoring as well as quantification of the amyloid fibrilization in specific cells, such as neurons, in a noninvasive manner and with the progression of aging and upon perturbation of the PN. FLIM is independent of the expression levels of the fluorophore and enables an analysis of the aggregation process without any further staining or bleaching. Fluorophores are quenched when they are in close vicinity of amyloid structures, which results in a decrease of the fluorescence lifetime. The quenching directly correlates with the aggregation of the amyloid protein. FLIM is a versatile technique that can be applied to compare the fibrilization process of different amyloid proteins, environmental stimuli, or genetic backgrounds in vivo in a non-invasive manner.

Characterization of Amyloid Structures in Aging C. Elegans Using Fluorescence Lifetime Imaging

Fluorescence lifetime imaging monitors, quantifies and distinguishes the aggregation tendencies of proteins in living, aging, and stressed C. elegans disease models.

Amyloid fibrils are associated with a number of neurodegenerative diseases such as Huntington&#39;s, Parkinson&#39;s, or Alzheimer&#39;s disease. These ...

Biochemistry

Monitoring Protein Aggregation Kinetics In Vivo using Automated Inclusion Counting in Caenorhabditis elegans

Protein aggregation into insoluble inclusions is a hallmark of a variety of human diseases, many of which are age-related. The nematode Caenorhabditis elegans is a well-established model organism that has been widely used in the field to study protein aggregation and toxicity. Its optical transparency enables the direct visualization of protein aggregation by fluorescence microscopy. Moreover, the fast reproductive cycle and short lifespan make the nematode a suitable model to screen for genes and molecules that modulate this process.
However, the quantification of aggregate load in living animals is poorly standardized, typically performed by manual inclusion counting under a fluorescence dissection microscope at a single time point. This approach can result in high variability between observers and limits the understanding of the aggregation process. In contrast, amyloid-like protein aggregation in vitro is routinely monitored by thioflavin T fluorescence in a highly quantitative and time-resolved fashion.
Here, an analogous method is presented for the unbiased analysis of aggregation kinetics in living C. elegans, using a high-throughput confocal microscope combined with custom-made image analysis and data fitting. The applicability of this method is demonstrated by monitoring inclusion formation of a fluorescently labeled polyglutamine (polyQ) protein in the body wall muscle cells. The image analysis workflow allows the determination of the numbers of inclusions at different timepoints, which are fitted to a mathematical model based on independent nucleation events in individual muscle cells. The method described here may prove useful to assess the effects of proteostasis factors and potential therapeutics for protein aggregation diseases in a living animal in a robust and quantitative manner.

Monitoring Protein Aggregation Kinetics In Vivo using Automated Inclusion Counting in Caenorhabditis elegans

Here, a method is presented for the analysis of protein aggregation kinetics in the nematode Caenorhabditis elegans. Animals from an age-synchronized population are imaged at different time points, followed by semiautomated inclusion counting in CellProfiler and fitting to a mathematical model in AmyloFit.

Protein aggregation into insoluble inclusions is a hallmark of a variety of human diseases, many of which are age-related. The nematode Caenorhabditis ...

Solid Plate-based Dietary Restriction in Caenorhabditis elegans

Reduction of food intake without malnutrition or starvation is known to increase lifespan and delay the onset of various age-related diseases in a wide range of species, including mammals. It also causes a decrease in body weight and fertility, as well as lower levels of plasma glucose, insulin, and IGF-1 in these animals. This treatment is often referred to as dietary restriction (DR) or caloric restriction (CR). The nematode Caenorhabditis elegans has emerged as an important model organism for studying the biology of aging. Both environmental and genetic manipulations have been used to model DR and have shown to extend lifespan in C. elegans. However, many of the reported DR studies in C. elegans were done by propagating animals in liquid media, while most of the genetic studies in the aging field were done on the standard solid agar in petri plates. Here we present a DR protocol using standard solid NGM agar-based plate with killed bacteria.

Solid Plate-based Dietary Restriction in Caenorhabditis elegans

Here we present a protocol for performing solid plate-based dietary restriction in C. elegans with killed bacteria.

Reduction of food intake without malnutrition or starvation is known to increase lifespan and delay the onset of various age-related diseases in a wide ...

Using Caenorhabditis elegans as a Model System to Study Protein Homeostasis in a Multicellular Organism

The folding and assembly of proteins is essential for protein function, the long-term health of the cell, and longevity of the organism. Historically, the function and regulation of protein folding was studied in vitro, in isolated tissue culture cells and in unicellular organisms. Recent studies have uncovered links between protein homeostasis (proteostasis), metabolism, development, aging, and temperature-sensing. These findings have led to the development of new tools for monitoring protein folding in the model metazoan organism Caenorhabditis elegans. In our laboratory, we combine behavioral assays, imaging and biochemical approaches using temperature-sensitive or naturally occurring metastable proteins as sensors of the folding environment to monitor protein misfolding. Behavioral assays that are associated with the misfolding of a specific protein provide a simple and powerful readout for protein folding, allowing for the fast screening of genes and conditions that modulate folding. Likewise, such misfolding can be associated with protein mislocalization in the cell. Monitoring protein localization can, therefore, highlight changes in cellular folding capacity occurring in different tissues, at various stages of development and in the face of changing conditions. Finally, using biochemical tools ex vivo, we can directly monitor protein stability and conformation. Thus, by combining behavioral assays, imaging and biochemical techniques, we are able to monitor protein misfolding at the resolution of the organism, the cell, and the protein, respectively.

Using Caenorhabditis elegans as a Model System to Study Protein Homeostasis in a Multicellular Organism

To study the relationship between protein homeostasis, stress and aging, we monitored changes in protein folding by following protein dysfunction, protein localization in the cell and protein stability at the organismal, cellular and protein levels, using the genetically tractable metazoan Caenorhabditis elegans as a model system.

The folding and assembly of proteins is essential for protein function, the long-term health of the cell, and longevity of the organism. Historically, the ...

Quantifying Tissue-Specific Proteostatic Decline in Caenorhabditis elegans

The ability to maintain proper function and folding of the proteome (protein homeostasis) declines during normal aging, facilitating the onset of a growing number of age-associated diseases. For instance, proteins with polyglutamine expansions are prone to aggregation, as exemplified with the huntingtin protein and concomitant onset of Huntington&#8217;s disease. The age-associated deterioration of the proteome has been widely studied through the use of transgenic Caenorhabditis elegans expressing polyQ repeats fused to a yellow fluorescent protein (YFP). This polyQ::YFP transgenic animal model facilitates the direct quantification of the age-associated decline of the proteome through imaging the progressive formation of fluorescent foci (i.e., protein aggregates) and subsequent onset of locomotion defects that develop as a result of the collapse of the proteome. Further, the expression of the polyQ::YFP transgene can be driven by tissue-specific promoters, allowing the assessment of proteostasis across tissues in the context of an intact multicellular organism. This model is highly amenable to genetic analysis, thus providing an approach to quantify aging that is complementary to lifespan assays. We describe how to accurately measure polyQ::YFP foci formation within either neurons or body wall muscle during aging, and the subsequent onset of behavioral defects. Next, we highlight how these approaches can be adapted for higher throughput, and potential future applications using other emerging strategies for C. elegans genetic analysis.

Quantifying Tissue-Specific Proteostatic Decline in Caenorhabditis elegans

Proteostatic decline is a hallmark of aging, facilitating the onset of neurodegenerative diseases. We outline a protocol to quantifiably measure proteostasis in two different Caenorhabditis elegans tissues through heterologous expression of polyglutamine repeats fused to a fluorescent reporter. This model allows rapid in vivo genetic analysis of proteostasis.

The ability to maintain proper function and folding of the proteome (protein homeostasis) declines during normal aging, facilitating the onset of a ...

Modeling Age-Associated Neurodegenerative Diseases in Caenorhabditis elegans

Battling human neurodegenerative pathologies and managing their pervasive socioeconomic impact is becoming a global priority. Notwithstanding their detrimental effects on the human life quality and the healthcare system, the majority of human neurodegenerative disorders still remain incurable and non-preventable. Therefore, the development of novel therapeutic interventions against such maladies is becoming a pressing urgency. Age-associated deterioration of neuronal circuits and function is evolutionarily conserved in organisms as diverse as the lowly worm Caenorhabditis elegans and humans, signifying similarities in the underlying cellular and molecular mechanisms. C. elegans is a highly malleable genetic model, which offers a well-characterized nervous system, body transparency and a diverse repertoire of genetic and imaging techniques to assess neuronal activity and quality control during ageing. Here, we introduce and describe methodologies utilizing some versatile nematode models, including hyperactivated ion channel-induced necrosis (e.g., deg-3(d) and mec-4(d)) and protein aggregate (e.g., &#945;-syunclein and poly-glutamate)-induced neurotoxicity, to monitor and dissect the cellular and molecular underpinnings of age-related neuronal breakdown. A combination of these animal neurodegeneration models, together with genetic and pharmacological screens for cell death modulators will lead to an unprecedented understanding of age-related breakdown of neuronal function and will provide critical insights with broad relevance to human health and quality of life.

Modeling Age-Associated Neurodegenerative Diseases in Caenorhabditis elegans

Here, we introduce and describe widely accessible methodologies utilizing some versatile nematode models, including hyperactivated ion channel-induced necrosis and protein aggregate-induced neurotoxicity, to monitor and dissect the cellular and molecular underpinnings of age-associated neurodegenerative diseases.

Battling human neurodegenerative pathologies and managing their pervasive socioeconomic impact is becoming a global priority. Notwithstanding their ...

Assessment of de novo Protein Synthesis Rates in Caenorhabditis elegans

Maintaining a healthy proteome is essential for cell and organismal homeostasis. Perturbation of the balance between protein translational control and degradation instigates a multitude of age-related diseases. Decline of proteostasis quality control mechanisms is a hallmark of ageing. Biochemical methods to detect de novo protein synthesis are still limited, have several disadvantages and cannot be performed in live cells or animals. Caenorhabditis elegans, being transparent and easily genetically modified, is an excellent model to monitor protein synthesis rates by using imaging techniques. Here, we introduce and describe a method to measure de novo protein synthesis in vivo utilizing fluorescence recovery after photobleaching (FRAP). Transgenic animals expressing fluorescent proteins in specific cells or tissues are irradiated by a powerful light source resulting in fluorescence photobleaching. In turn, assessment of fluorescence recovery signifies new protein synthesis in cells and/or tissues of interest. Hence, the combination of transgenic nematodes, genetic and/or pharmacological interventions together with live imaging of protein synthesis rates can shed light on mechanisms mediating age-dependent proteostasis collapse.

Assessment of de novo Protein Synthesis Rates in Caenorhabditis elegans

Here, we introduce and describe a nonradioactive and noninvasive method to assess de novo protein synthesis in vivo, utilizing the nematode Caenorhabditis elegans and fluorescence recovery after photobleaching (FRAP). This method can be combined with genetic and/or pharmacological screens to identify novel modulators of protein synthesis.

Maintaining a healthy proteome is essential for cell and organismal homeostasis. Perturbation of the balance between protein translational control and ...

Quantification of Insoluble Protein Aggregation in Caenorhabditis elegans during Aging with a Novel Data-Independent Acquisition Workflow

We and others have shown that the aging process results in a proteome-wide accumulation of insoluble proteins. Knocking down genes encoding the insoluble proteins over 40% of the time results in an extension of the lifespan in C. elegans, suggesting that many of these proteins are key determinants of the aging process. Isolation and quantitative identification of these insoluble proteins are crucial to understand key biological processes that occur during aging. Here, we present a modified and improved protocol that details how to extract and isolate the SDS-insoluble proteins (insolublome) from C. elegans more efficiently to streamline mass spectrometric workflows via a novel label-free quantitative proteomics analysis. This improved protocol utilizes a highly efficient sonicator for worm lysis that greatly increases efficiency for protein extraction and allows us to use significantly less starting material (approximately 3,000 worms) than in previous protocols (typically using at least 40,000 worms). Subsequent quantitative proteomic analysis of the insolublome was performed using data-dependent acquisition (DDA) for protein discovery and identification and data-independent acquisition (DIA) for comprehensive and more accurate protein quantification. Bioinformatic analysis of quantified proteins provides potential candidates that can be easily followed up with other molecular methods in C. elegans. With this workflow, we routinely identify more than 1000 proteins and quantify more than 500 proteins. This new protocol enables efficient compound screening with C. elegans. Here, we validated and applied this improved protocol to wild-type C. elegans N2-Bristol strain and confirmed that aged day-10 N2 worms showed greater accumulation of the insolublome than day-2 young worms.

Quantification of Insoluble Protein Aggregation in Caenorhabditis elegans during Aging with a Novel Data-Independent Acquisition Workflow

This novel workflow efficiently extracts and isolates SDS-insoluble proteins (insolublome) from Caenorhabditis elegans with minimal starting material for quantitative differential proteomic analysis. The protocol uses a comprehensive data-independent acquisition mass spectrometry analysis to quantify the insolublome and bioinformatic analysis to gain biological insights into aging mechanisms and pathologies.

We and others have shown that the aging process results in a proteome-wide accumulation of insoluble proteins. Knocking down genes encoding the insoluble ...

Automating Aggregate Quantification in Caenorhabditis elegans

A rise in the prevalence of neurodegenerative protein conformational diseases (PCDs) has fostered a great interest in this subject over the years. This increased attention has called for the diversification and improvement of animal models capable of reproducing disease phenotypes observed in humans with PCDs. Though murine models have proven invaluable, they are expensive and are associated with laborious, low-throughput methods. Use of the Caenorhabditis elegans nematode model to study PCDs has been justified by its relative ease of maintenance, low cost, and rapid generation time, which allow for high-throughput applications. Additionally, high conservation between the C. elegans and human genomes makes this model an invaluable discovery tool. Nematodes that express fluorescently tagged tissue-specific polyglutamine (polyQ) tracts exhibit age- and polyQ length-dependent aggregation characterized by fluorescent foci. Such reporters are often employed as proxies to monitor changes in proteostasis across tissues. Manual aggregate quantification is time-consuming, limiting experimental throughput. Furthermore, manual foci quantification can introduce bias, as aggregate identification can be highly subjective. Herein, a protocol consisting of worm culturing, image acquisition, and data processing was standardized to support high-throughput aggregate quantification using C. elegans that express intestine-specific polyQ. By implementing a C. elegans-based image processing pipeline using CellProfiler, an image analysis software, this method has been optimized to separate and identify individual worms and enumerate their respective aggregates. Though the concept of automation is not entirely unique, the need to standardize such procedures for reproducibility, elimination of bias from manual counting, and increase throughput is high. It is anticipated that these methods can drastically simplify the screening process of large bacterial, genomic, or drug libraries using the C. elegans model.

Automating Aggregate Quantification in Caenorhabditis elegans

The following protocol describes the development and optimization of a high-throughput workflow for worm culturing, fluorescence imaging, and automated image processing to quantify polyglutamine aggregates as an assessment of changes in proteostasis.

A rise in the prevalence of neurodegenerative protein conformational diseases (PCDs) has fostered a great interest in this subject over the years. This ...

Fluorescent Reporter-Based Paralysis Assay: A Technique to Assess Age-Associated Progressive Formation of Polyglutamine Fluorescent Reporter and Associated Paralysis in Caenorhabditis elegans

Source: Lazaro-Pena, M. I. et al. <a href="https://app.jove.com/v/61100">Quantifying Tissue-Specific Proteostatic Decline in Caenorhabditis elegans.</a>&#160;J. Vis. Exp. (2021)
This video demonstrates an in vivo imaging-based assay to determine proteostasis decline due to aging. The assay uses Caenorhabditis elegans expressing polyglutamine YFP-fusion protein in body wall muscles to measure the age-associated aggregation of polyglutamine and induction of proteotoxicity, leading to paralysis.

Methods to Study Changes in Inherent Protein Aggregation with Age in Caenorhabditis elegans

Summary

Explore More Videos

Characterization of Amyloid Structures in Aging C. Elegans Using Fluorescence Lifetime Imaging

Monitoring Protein Aggregation Kinetics In Vivo using Automated Inclusion Counting in Caenorhabditis elegans

Solid Plate-based Dietary Restriction in Caenorhabditis elegans

Using Caenorhabditis elegans as a Model System to Study Protein Homeostasis in a Multicellular Organism

Quantifying Tissue-Specific Proteostatic Decline in Caenorhabditis elegans

Modeling Age-Associated Neurodegenerative Diseases in Caenorhabditis elegans

Assessment of de novo Protein Synthesis Rates in Caenorhabditis elegans

Quantification of Insoluble Protein Aggregation in Caenorhabditis elegans during Aging with a Novel Data-Independent Acquisition Workflow

Automating Aggregate Quantification in Caenorhabditis elegans

Fluorescent Reporter-Based Paralysis Assay: A Technique to Assess Age-Associated Progressive Formation of Polyglutamine Fluorescent Reporter and Associated Paralysis in Caenorhabditis elegans