Name: measuring diurnal rhythms in autophagic and proteasomal flux
Uploaded: 2019-09-17T14:00:00
Description: Watch this Scientific Journal Video about Measuring Diurnal Rhythms in Autophagic and Proteasomal Flux at JoVE.com

This work was funded by RO1HL135846 and a Children&#8217;s Development Institute grant (PD-II-2016-529).

The protocol described here was approved by the Washington University in St. Louis Animal Care and Use Committee (IACUC).
1. Mouse Housing and Experimental Design
<ol>
	<li>To detect daily rhythms in protein turnover, house mice (male or female C57BL/6J, 4&#8722;8 week old, 20&#8722;25 g) under standard 12 h light/dark cycles with food provided ad libitum. To avoid stressing the animals, acclimate mice for at least one week in the facility prior to use and avoid single housing. For ...

<ol>
	<li>Green, C. B., Takahashi, J. S., Bass, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+meter+of+metabolism.">The meter of metabolism.</a> Cell. 134 (5), 728-742 (2008).</li><li>Ma, B. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=LPS+suppresses+expression+of+asialoglycoprotein-binding+protein+through+TLR4+in+thioglycolate-elicited+peritoneal+macrophages.">LPS suppresses expression of asialoglycoprotein-binding protein through TLR4 in thioglycolate-elicited peritoneal macrophages.</a> Glycoconjugate Journal. 24 (4-5), 243-249 (2007).</li><li>Ryzhikov, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diurnal+Rhythms+Spatially+and+Temporally+Organize+Autophagy.">Diurnal Rhythms Spatially and Temporally Organize Autophagy.</a> Cell Reports. 26 (7), 1880-1892 (2019).</li><li>Martinez-Lopez, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=System-wide+Benefits+of+Intermeal+Fasting+by+Autophagy.">System-wide Benefits of Intermeal Fasting by Autophagy.</a> Cell Metabolism. 26 (6), 856-871 (2017).</li><li>Desvergne, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Circadian+modulation+of+proteasome+activity+and+accumulation+of+oxidized+protein+in+human+embryonic+kidney+HEK+293+cells+and+primary+dermal+fibroblasts.">Circadian modulation of proteasome activity and accumulation of oxidized protein in human embryonic kidney HEK 293 cells and primary dermal fibroblasts.</a> Free Radical Biology and Medicine. 94, 195-207 (2016).</li><li>Levine, B., Mizushima, N., Virgin, H. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Autophagy+in+immunity+and+inflammation.">Autophagy in immunity and inflammation.</a> Nature. 469 (7330), 323-335 (2011).</li><li>Ciechanover, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intracellular+protein+degradation:+from+a+vague+idea+thru+the+lysosome+and+the+ubiquitin-proteasome+system+and+onto+human+diseases+and+drug+targeting.">Intracellular protein degradation: from a vague idea thru the lysosome and the ubiquitin-proteasome system and onto human diseases and drug targeting.</a> Cell Death &amp; Differentiation. 12 (9), 1178-1190 (2005).</li><li>Collins, G. A., Goldberg, A. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Logic+of+the+26S+Proteasome.">The Logic of the 26S Proteasome.</a> Cell. 169 (5), 792-806 (2017).</li><li>Haspel, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+macroautophagic+flux+in+vivo+using+a+leupeptin-based+assay.">Characterization of macroautophagic flux in vivo using a leupeptin-based assay.</a> Autophagy. 7 (6), 629-642 (2011).</li><li>Klionsky, D. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Guidelines+for+the+use+and+interpretation+of+assays+for+monitoring+autophagy+(3rd+edition).">Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition).</a> Autophagy. 12 (1), 1-222 (2016).</li><li>Eckel-Mahan, K., Sassone-Corsi, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phenotyping+Circadian+Rhythms+in+Mice.">Phenotyping Circadian Rhythms in Mice.</a> Current Protocols in Mouse Biology. 5 (3), 271-281 (2015).</li><li>Hughes, M. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Guidelines+for+Genome-Scale+Analysis+of+Biological+Rhythms.">Guidelines for Genome-Scale Analysis of Biological Rhythms.</a> Journal of Biological Rhythms. 32 (5), 380-393 (2017).</li></ol>

Our protocol describes a technically straightforward means of measuring biological rhythms in protein turnover in mice using commonly available molecular biology equipment. Because of the length of time series experiments and the number of biological samples involved, it is important to be consistent across the entire experiment regarding how the mice are injected, the timing of tissue acquisition and the biochemical processing of samples. The injection, euthanasia, and cervical dislocation steps may require operator pra...

Circadian rhythms refer to daily, predictable variations in biological function that are apparent throughout nature. They exist at every biological scale, from macroscopic behaviors like sleep-wake cycles, to molecular phenomena like the rhythmic abundance of biomolecules. In recent years, research into circadian rhythms has been transformed by the discovery of &#8220;clock genes&#8221; that are critical for circadian rhythm generation. Studies in clock gene knockout mice have revealed a central role for circadian rhythms in temporally organizing core cellular processes such as metabolism1. Among the ways circadian rhythms make this happen is by imparting a temporal structure to protein catabolism.
Several groups including ours have shown that the two major avenues for cellular protein catabolism, autophagy and the ubiquitin-proteasome system, are subject to diurnal rhythms2,3,4,5. Autophagy represents the lysosome-dependent arm of protein catabolism in which proteins of interest are delivered to this degradative organelle either through the construction of a novel vesicle (macroautophagy) or through direct translocation though a channel (chaperone mediated autophagy)6. The ubiquitin-proteasome system is the main non-lysosomal pathway, where proteins are poly-ubiquitinated and then fed into the proteasome, a macromolecular degradative machine found throughout the cytoplasm and nucleus7,8. Rhythms in autophagic and proteasomal activity are important because they likely play a role in cellular housekeeping. As a result, it is valuable to have a standardized procedure that can detect daily oscillations in protein catabolism that is compatible with pre-clinical disease models.
Here, we provide our protocol for quantifying diurnal variations in autophagic flux in mouse liver, which has served as the basis for work in our laboratory3,9. Our method is classified as a &#8220;turnover assay&#8221;10, an approach used by numerous groups to measure proteolytic activity (or flux). In this approach, protease inhibitors specific to lysosomes or proteasomes are administered to mice and then tissue samples are obtained after a fixed time interval. In parallel, tissue samples are obtained from mice subjected to sham injections. The tissue samples are homogenized and then biochemically separated to obtain the lysosome-enriched and cytoplasmic fractions. These fractions are then analyzed in parallel via western blotting using antibodies specific to macroautophagy markers (LC3b and p62) or proteasomal substrates (poly-ubiquitinated protein). Over time, animals injected with protease inhibitors accumulate proteins that would normally have been recycled. As a result, the rate of turnover is inferred by comparing the abundance of marker proteins in the protease-inhibitor treated samples to the sham-treated samples. By repeating this method at fixed time intervals across the day it is possible to reconstruct circadian variations in proteolysis (Figure 1A).

<table>
	<tbody>
		<tr>
			<td>4x SDS PAGE Sample Buffer</td>
			<td>Invitrogen</td>
			<td>Cat# NP0008</td>
			<td></td>
		</tr>
		<tr>
			<td>Bortezomib</td>
			<td>EMD Millipore</td>
			<td>Cat# 5.04314.0001; CAS: 179324-69-7</td>
			<td></td>
		</tr>
		<tr>
			<td>Image Studio</td>
			<td>LICOR</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Immobilon-FL PVDF membrane 0.45 micron</td>
			<td>Merck Millipore Ltd</td>
			<td>Cat# IPFL00010</td>
			<td></td>
		</tr>
		<tr>
			<td>K48-linkage Specific Polyubiquitin (D9D5) Rabbit mAb</td>
			<td>Cell Signaling Technology</td>
			<td>Cat#8081S; RRID:AB_10859893</td>
			<td></td>
		</tr>
		<tr>
			<td>LC3a</td>
			<td>Boston Biochem</td>
			<td>Cat# UL-430</td>
			<td></td>
		</tr>
		<tr>
			<td>LC3b antibody</td>
			<td>Novus</td>
			<td>Cat#NB100-2220; RRID:AB_10003146</td>
			<td></td>
		</tr>
		<tr>
			<td>LC3b antibody</td>
			<td>Cell Signaling Technology</td>
			<td>Cat#2775; RRID:AB_915950</td>
			<td></td>
		</tr>
		<tr>
			<td>Leupeptin</td>
			<td>Sigma</td>
			<td>Cat# L2884; CAS: 103476-89-7</td>
			<td></td>
		</tr>
		<tr>
			<td>NuPAGE 4-12% Bis-Tris Midi Protein Gels</td>
			<td>Thermo Fisher Scientific</td>
			<td>Cat# WG1403BOX</td>
			<td></td>
		</tr>
		<tr>
			<td>NuPAGE LDS Sample Buffer (4x)</td>
			<td>Thermo Fisher Scientific</td>
			<td>Cat# NP0007</td>
			<td></td>
		</tr>
		<tr>
			<td>P62-his</td>
			<td>Novus</td>
			<td>Cat# NBP1-44490</td>
			<td></td>
		</tr>
		<tr>
			<td>Precision Plus Protein All Blue Prestained Protein Standards</td>
			<td>Bio-Rad</td>
			<td>Cat# 1610373</td>
			<td></td>
		</tr>
		<tr>
			<td>Rabbit Anti-p62/SQSTM1</td>
			<td>Millipore-Sigma</td>
			<td>Cat#P0067; RRID:AB_1841064</td>
			<td></td>
		</tr>
		<tr>
			<td>rhPoly-Ub WT (2-7) (K48)</td>
			<td>Boston Biochem</td>
			<td>Cat# UC-230</td>
			<td></td>
		</tr>
		<tr>
			<td>SDS-PAGE Midi-size Gels</td>
			<td>Invitrogen</td>
			<td>Cat# WG1403</td>
			<td></td>
		</tr>
		<tr>
			<td>SIGMAFAST Protease Inhibitor Tablets</td>
			<td>Millipore-Sigma</td>
			<td>Cat# S8830</td>
			<td></td>
		</tr>
	</tbody>
</table>

measuring diurnal rhythms in autophagic and proteasomal flux

Cells employ several methods for recycling unwanted proteins and other material, including lysosomal and non-lysosomal pathways. The main lysosome-dependent pathway is called autophagy, while the primary non-lysosomal method for protein catabolism is the ubiquitin-proteasome system. Recent studies in model organisms suggest that the activity of both autophagy and the ubiquitin-proteasome system is not constant across the day but instead varies according to a daily (circadian) rhythm. The ability to measure biological rhythms in protein turnover is important for understanding how cellular quality control is achieved and for understanding the dynamics of specific proteins of interest. Here we present a standardized protocol for quantifying autophagic and proteasomal flux in vivo that captures the circadian component of protein turnover. Our protocol includes details for mouse handling, tissue processing, fractionation, and autophagic flux quantification using mouse liver as the starting material.

Representative data are presented in Figure 2A,B, and the quantification of these data are provided in Figure 2C,D (see also Supplemental File &#8220;Sample Data&#8221;). For simplicity, we have not depicted loading controls in Figure 2 but these should be obtained in parallel. Typically, western blots against &#946;-actin are used for this purpose, but a total protein stain (such a...

Watch this Scientific Journal Video about Measuring Diurnal Rhythms in Autophagic and Proteasomal Flux at JoVE.com

Measuring Diurnal Rhythms in Autophagic and Proteasomal Flux

We describe our protocol for measuring biological rhythms in protein catabolism via autophagy and the proteasome in mouse liver.

Cells employ several methods for recycling unwanted proteins and other material, including lysosomal and non-lysosomal pathways. The main ...

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