Name: methods to study changes in inherent protein aggregation with age in caenorhabditis elegans
Uploaded: 2017-11-26T13:00:00
Description: Watch this Scientific Journal Video about Methods to Study Changes in Inherent Protein Aggregation with Age in Caenorhabditis elegans at JoVE.com

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

NOTE: For a better understanding of the procedure, a schematic of the workflow (Figure 1) is attached.
1. Growth of Large Numbers of Young and Aged C. elegans Subjected to RNAi Targeting a Gene of Interest
NOTE: Use C. elegans temperature-induced sterile gon-2(q388) mutants (CF2253) to obtain large aged-synchronized populations. During all steps, it is important to work under semi-sterile conditions with an open...

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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.

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			<td class="xl18" height="40" style="width:161pt;height:30.0pt" width="215">Sequencing Grade Modified Trypsin</td>
			<td class="xl18" style="width:92pt" width="122">Promega</td>
			<td class="xl25" style="width:258pt" width="344">V5111</td>
			<td class="xl18" style="width:125pt" width="166"></td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl18" height="40" style="width:161pt;height:30.0pt" width="215">Isobaric tags for relative and absolute quantitation</td>
			<td class="xl18" style="width:92pt" width="122">Sciex</td>
			<td class="xl19">4352135</td>
			<td class="xl18" style="width:125pt" width="166">iTRAQ Reagents Multiplex Kit</td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl17" height="40" style="height:30.0pt">Centrifuge Avanti J-26XP</td>
			<td class="xl18" style="width:92pt" width="122">Beckmann Coulter</td>
			<td class="xl19">393126</td>
			<td class="xl17"></td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl17" height="40" style="height:30.0pt">Ultracentrifuge Optima Max-XP</td>
			<td class="xl18" style="width:92pt" width="122">Beckmann Coulter</td>
			<td class="xl19">393315</td>
			<td class="xl17"></td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl17" height="40" style="height:30.0pt">Centrifuge 5424R</td>
			<td class="xl18" style="width:92pt" width="122">Eppendorf</td>
			<td class="xl19">5404000413</td>
			<td class="xl17"></td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl17" height="40" style="height:30.0pt">Centrifuge 5702</td>
			<td class="xl18" style="width:92pt" width="122">Eppendorf</td>
			<td class="xl19">5702000329</td>
			<td class="xl17"></td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl17" height="40" style="height:30.0pt">Centrifuge Megafuge 40R</td>
			<td class="xl18" style="width:92pt" width="122">Thermo Scientific</td>
			<td class="xl19">75004518</td>
			<td class="xl17"></td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl17" height="40" style="height:30.0pt">Concentrator Plus</td>
			<td class="xl18" style="width:92pt" width="122">Eppendorf</td>
			<td class="xl19">5305000304</td>
			<td class="xl17">Centrifugal evaporator</td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl18" height="40" style="width:161pt;height:30.0pt" width="215">Fluorescent stereo-microscope M165 FC&#160;</td>
			<td class="xl18" style="width:92pt" width="122">Leica</td>
			<td class="xl19"></td>
			<td class="xl18" style="width:125pt" width="166">With Planapo 2.0x objective</td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl17" height="40" style="height:30.0pt">Dissection microscope</td>
			<td class="xl18" style="width:92pt" width="122">Leica&#160;</td>
			<td class="xl19"></td>
			<td class="xl17">Leica S6E</td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl18" height="80" rowspan="2" style="width:161pt;height:60.0pt" width="215">High magnification microscope Zeiss Axio Observer Z1</td>
			<td class="xl18" height="80" rowspan="2" style="width:92pt;height:60.0pt" width="122">Zeiss</td>
			<td class="xl19" height="80" rowspan="2" style="width:258pt;height:60.0pt" width="344"></td>
			<td class="xl16" height="80" rowspan="2" style="width:125pt;height:60.0pt" width="166">With PlanAPOCHROMAT 20x objective and Zeiss Axio Cam MRm</td>
		</tr>
		<tr height="40" style="height:30.0pt">
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl32" height="40" style="height:30.0pt">Software</td>
			<td class="xl33" style="width:92pt" width="122"></td>
			<td class="xl32"></td>
			<td class="xl17"></td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl17" height="40" style="height:30.0pt">Image analysis software</td>
			<td class="xl18" style="width:92pt" width="122">ImageJ</td>
			<td class="xl19"></td>
			<td class="xl17"></td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl18" height="40" style="width:161pt;height:30.0pt" width="215">Analysis of mass spectrometry data</td>
			<td class="xl18" style="width:92pt" width="122">Protein Prospector</td>
			<td class="xl136" style="width:258pt" width="344"></td>
			<td class="xl137">http://prospector.ucsf.edu/prospector/mshome.htm</td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl32" height="40" style="height:30.0pt">E.coli strain</td>
			<td class="xl33" style="width:92pt" width="122"></td>
			<td class="xl19"></td>
			<td class="xl17"></td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl17" height="40" style="height:30.0pt">OP50</td>
			<td class="xl18" style="width:92pt" width="122">CGC</td>
			<td class="xl19"></td>
			<td class="xl17"></td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl32" height="40" style="height:30.0pt">RNAi bacteria</td>
			<td class="xl33" style="width:92pt" width="122"></td>
			<td class="xl19"></td>
			<td class="xl17"></td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl17" height="40" style="height:30.0pt">L4440</td>
			<td class="xl18" style="width:92pt" width="122">Julie Ahringer RNAi library</td>
			<td class="xl19"></td>
			<td class="xl17"></td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td class="xl32" height="42" rowspan="2" style="width:161pt;height:31.5pt" width="215">C. elegans mutants</td>
			<td class="xl33" height="42" rowspan="2" style="width:92pt;height:31.5pt" width="122"></td>
			<td class="xl32" height="42" rowspan="2" style="width:258pt;height:31.5pt" width="344"></td>
			<td class="xl19" height="42" rowspan="2" style="width:125pt;height:31.5pt" width="166"></td>
		</tr>
		<tr height="21" style="height:15.75pt">
		</tr>
		<tr height="42" style="height:31.5pt">
			<td class="xl17" height="42" style="height:31.5pt">CF2253</td>
			<td class="xl18" style="width:92pt" width="122">CGC, strain name: EJ1158&#160;</td>
			<td class="xl40" style="width:258pt" width="344"></td>
			<td class="xl17">Genotype: gon-2(q388)</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td class="xl33" height="42" rowspan="2" style="width:161pt;height:31.5pt" width="215">C. elegans transgenics</td>
			<td class="xl33" height="42" rowspan="2" style="width:92pt;height:31.5pt" width="122"></td>
			<td class="xl32" height="42" rowspan="2" style="width:258pt;height:31.5pt" width="344"></td>
			<td class="xl19" height="42" rowspan="2" style="width:125pt;height:31.5pt" width="166"></td>
		</tr>
		<tr height="21" style="height:15.75pt">
		</tr>
		<tr height="21" style="height:15.75pt">
			<td class="xl18" height="42" rowspan="2" style="width:161pt;height:31.5pt" width="215">DCD214</td>
			<td class="xl25" height="42" rowspan="2" style="width:92pt;height:31.5pt" width="122">Della David&#39;s lab at DZNE T&#252;bingen</td>
			<td class="xl40" height="42" rowspan="2" style="width:258pt;height:31.5pt" width="344"></td>
			<td class="xl68" height="42" rowspan="2" style="width:125pt;height:31.5pt" width="166">Genotype: N2; uqIs24[Pmyo-2::tagrfp::pab-1]</td>
		</tr>
		<tr height="21" style="height:15.75pt">
		</tr>
		<tr height="21" style="height:15.75pt">
			<td class="xl17" height="42" rowspan="2" style="width:161pt;height:31.5pt" width="215">DCD215</td>
			<td class="xl87" height="42" rowspan="2" style="width:92pt;height:31.5pt" width="122">Della David&#39;s lab at DZNE T&#252;bingen</td>
			<td class="xl40" height="42" rowspan="2" style="width:258pt;height:31.5pt" width="344"></td>
			<td class="xl68" height="42" rowspan="2" style="width:125pt;height:31.5pt" width="166">Genotype: daf-2(e1370) III; uqIs24[Pmyo-2::tagrfp::pab-1]</td>
		</tr>
		<tr height="21" style="height:15.75pt">
		</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 ...

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Biology

Solid Plate-based Dietary Restriction in Caenorhabditis elegans

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 ...

Time-lapse Microscopy of Early Embryogenesis in Caenorhabditis elegans

Time-lapse Microscopy of Early Embryogenesis in Caenorhabditis elegans

Caenorhabditis elegans has often been used as a model system in studies of early developmental processes.  The transparency of the 
embryos, the genetic ...

Basic Caenorhabditis elegans Methods: Synchronization and Observation

Basic Caenorhabditis elegans Methods: Synchronization and Observation

Research into the molecular and developmental biology of the nematode Caenorhabditis elegans was begun in the early seventies by Sydney Brenner and it has ...

4D Imaging of Protein Aggregation in Live Cells

One of the key tasks of any living cell is maintaining the proper folding of newly synthesized proteins in the face of ever-changing environmental ...

Prostaglandin Extraction and Analysis in Caenorhabditis elegans

Prostaglandin Extraction and Analysis in Caenorhabditis elegans

Caenorhabditis elegans is emerging as a powerful animal model to study the biology of lipids1-9. Prostaglandins are an important class of eicosanoids, ...

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

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 ...

In Vitro Aggregation Assays Using Hyperphosphorylated Tau Protein

In Vitro Aggregation Assays Using Hyperphosphorylated Tau Protein

Alzheimer's disease is one of a large group of neurodegenerative disorders known as tauopathies that are manifested by the neuronal deposits of ...

Cultivation of Caenorhabditis elegans in Three Dimensions in the Laboratory

Cultivation of Caenorhabditis elegans in Three Dimensions in the Laboratory

The use of genetic model organisms such as Caenorhabditis elegans has led to seminal discoveries in biology over the last five decades. Most of what we ...

Combined Nucleotide and Protein Extractions in Caenorhabditis elegans

Combined Nucleotide and Protein Extractions in Caenorhabditis elegans

A single biological sample holds a plethora of information, and it is now common practice to simultaneously investigate several macromolecules to capture ...

Modeling Age-Associated Neurodegenerative Diseases in Caenorhabditis elegans

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 ...