Name: measurement of basal and forskolin-stimulated lipolysis in inguinal adipose fat pads
Uploaded: 2017-07-21T12:30:00
Description: Watch this Scientific Journal Video about Measurement of Basal and Forskolin-stimulated Lipolysis in Inguinal Adipose Fat Pads at JoVE.com

This work was supported by the AHA Award No. 15BGIA23250030, the National Institute of General Medical Sciences of the NIH under award number 8P20 GM103432-12 and the University of Wyoming Faculty Grant in Aid to BT.

All protocols follow the animal care guidelines of the University of Wyoming.
1. Animal Housing and Feeding
NOTE: Adult male wild type mice (C57BL/6) (age 12 to 24 weeks) were bred in the research animal facility as per the Institutional Animal Care and Use Committee (IACUC) approved protocols.
<ol>
	<li>Starting from week 6 of age, house mice in groups of four in separate cages and randomly assign them into feeding groups of NCD or HFD (&#177; 0.01% CAP) until we...

<ol>
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I., Langin, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adipose+tissue+lipolysis.">Adipose tissue lipolysis.</a> Curr Opin Clin Nutr Metab Care. 13 (4), 377-381 (2010).</li><li>Baskaran, P., Krishnan, V., Ren, J., Thyagarajan, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Capsaicin+induces+browning+of+white+adipose+tissue+and+counters+obesity+by+activating+TRPV1+channel-dependent+mechanisms.">Capsaicin induces browning of white adipose tissue and counters obesity by activating TRPV1 channel-dependent mechanisms.</a> Br J Pharmacol. 173 (15), 2369-2389 (2016).</li><li>Yang, D., 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=Activation+of+TRPV1+by+dietary+capsaicin+improves+endothelium-dependent+vasorelaxation+and+prevents+hypertension.">Activation of TRPV1 by dietary capsaicin improves endothelium-dependent vasorelaxation and prevents hypertension.</a> Cell Metab. 12 (2), 130-141 (2010).</li><li>Ding, L., 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=Reduced+lipolysis+response+to+adipose+afferent+reflex+involved+in+impaired+activation+of+adrenoceptor-cAMP-PKA-hormone+sensitive+lipase+pathway+in+obesity.">Reduced lipolysis response to adipose afferent reflex involved in impaired activation of adrenoceptor-cAMP-PKA-hormone sensitive lipase pathway in obesity.</a> Sci Rep. 6, 34374 (2016).</li><li>Ohyama, K., 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=A+combination+of+exercise+and+capsinoid+supplementation+additively+suppresses+diet-induced+obesity+by+increasing+energy+expenditure+in+mice.">A combination of exercise and capsinoid supplementation additively suppresses diet-induced obesity by increasing energy expenditure in mice.</a> Am J Physiol Endocrinol Metab. 308 (4), E315-E323 (2015).</li><li>Beylot, M., Martin, C., Beaufrere, B., Riou, J. 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S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+skinny+on+fat:+lipolysis+and+fatty+acid+utilization+in+adipocytes.">The skinny on fat: lipolysis and fatty acid utilization in adipocytes.</a> Trends Endocrinol Metab. 20 (9), 424-428 (2009).</li><li>Jaworski, K., Sarkadi-Nagy, E., Duncan, R. E., Ahmadian, M., Sul, H. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+triglyceride+metabolism.+IV.+Hormonal+regulation+of+lipolysis+in+adipose+tissue.">Regulation of triglyceride metabolism. IV. Hormonal regulation of lipolysis in adipose tissue.</a> Am J Physiol Gastrointest Liver Physiol. 293 (1), G1-G4 (2007).</li><li>Jeppesen, J., Kiens, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+and+limitations+to+fatty+acid+oxidation+during+exercise.">Regulation and limitations to fatty acid oxidation during exercise.</a> J Physiol. 590 (5), 1059-1068 (2012).</li><li>Nakamura, M. T., Yudell, B. E., Loor, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+energy+metabolism+by+long-chain+fatty+acids.">Regulation of energy metabolism by long-chain fatty acids.</a> Prog Lipid Res. 53, 124-144 (2014).</li><li>Murray, A. J., Panagia, M., Hauton, D., Gibbons, G. 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The breakdown process of TGL into glycerol and fatty acids is catalyzed by ATGL9 during basal lipolysis and orchestrated by an array of proteins including the activation of adenylyl cyclase/PKA-dependent pathway during stimulated lipolysis21,22,23. Enhancement of lipolysis increases the plasma levels of fatty acids for transportation and energy use24. Fatty acids are taken up by mi...

Adipose tissues store energy as fat2 and fatty acid oxidation is required for thermogenesis3,4. Fatty acids ingested through diets are packaged along with apoproteins into chylomicrons and delivered to different tissues in the body via blood circulation. Although most cells in the body store a reserve of energy, adipose tissue stores excess energy as fat5,6. Lipolysis in adipose tissue is regulated by complex processes and the molecular details of lipolysis still remain vague7.
Lipolysis is a process by which triglycerides (TGL) stored in adipose tissue are hydrolyzed to produce glycerol and fatty acids (FA) by the enzyme adipose triglyceride lipase (ATGL)8. Alterations in basal and stimulated lipolysis is a characteristic feature of obesity. The basal lipolysis is regulated by ATGL activation9, which converts TGL to diacylglycerol (DAG), that is subsequently hydrolyzed to monoacyl glycerol (MAG). Activation of hormone sensitive lipase (HSL) via adenylyl cyclase activates cyclic adenosine monophosphate (cAMP) dependent protein kinase A (PKA) stimulation and causes lipolysis. Measurement of lipolysis, basal and stimulated, is, therefore, important to analyze the activity of proteins involved in this process. Also, unraveling the molecular regulation of lipolysis may be beneficial to develop novel therapeutic strategies against obesity10. Since, molecules that stimulate lipolysis and fatty acid oxidation are potential candidates for decreasing fats stored in depots, it is important to employ a robust assay for reproducibility.
Previously published data suggest that activation of TRPV1 protein expressed in white adipose tissue by CAP enhanced basal and FSK (adenylyl cyclase activator)-stimulated lipolysis in inguinal fat pads11. Previous research also suggests that long-term activation of TRPV1 by CAP activates PKA12. Since the activation of PKA stimulates lipolysis13,14, measuring both basal and PKA-dependent stimulated lipolysis in inguinal fat pads isolated from NCD or HFD (&#177; CAP)-fed mice after 32 weeks of feeding the respective diets will validate the role of TRPV1 activation in lipolysis.
This article describes an efficient method of determining basal and stimulated lipolysis. Although other methods that employ radioactive isotopes of glycerol and tedious high performance liquid chromatography or gas chromatography/mass spectrometry for measurements15,16 are available, this method offers a more direct, simple and cost effective technique to determine lipolysis in adipose tissues.

<table border="0" cellpadding="0" cellspacing="0" width="694">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Capsaicin</td>
			<td style="width:171px;">Sigma, USA</td>
			<td style="width:119px;">M2028</td>
			<td style="width:189px;">TRPV1 agonist</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Forskolin</td>
			<td style="width:171px;">Sigma, USA</td>
			<td style="width:119px;">F6886</td>
			<td>Adenylyl cyclase activator</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">DMEM</td>
			<td style="width:171px;">GE healthcare and life sciences, UT, USA</td>
			<td style="width:119px;">SH30081.01</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">High fat diet</td>
			<td style="width:171px;">Research diets, New Brunswick, USA</td>
			<td style="width:119px;">D12492</td>
			<td>Abbreviated as HFD</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Tris</td>
			<td style="width:171px;">Amresco, USA</td>
			<td style="width:119px;">O497</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sodium chloride</td>
			<td style="width:171px;">Thermofisher Scientific</td>
			<td style="width:119px;">BP358-212</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sodium deoxycholate</td>
			<td style="width:171px;">Sigma, USA</td>
			<td style="width:119px;">D6750</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Dithiothreitol</td>
			<td style="width:171px;">Sigma, USA</td>
			<td style="width:119px;">D9163</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sodium orthovanadate</td>
			<td style="width:171px;">Sigma, USA</td>
			<td style="width:119px;">S6508</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Protease inhibitor cocktail</td>
			<td style="width:171px;">Sigma, USA</td>
			<td style="width:119px;">P8340</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Free Glycerol reagent</td>
			<td style="width:171px;">Sigma USA</td>
			<td style="width:119px;">F6428</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">DMSO</td>
			<td style="width:171px;">Sigma, USA</td>
			<td style="width:119px;">D8779</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Triacsin C</td>
			<td style="width:171px;">Sigma, USA</td>
			<td style="width:119px;">T4540</td>
			<td>Acyl CoA transferase inhibitor</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Bovine serum albumin</td>
			<td style="width:171px;">Sigma, USA</td>
			<td style="width:119px;">A7030</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Chloroform</td>
			<td style="width:171px;">Sigma Aldrich</td>
			<td style="width:119px;">31998-8</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Methanol</td>
			<td style="width:171px;">Thermofisher Scientific, USA</td>
			<td style="width:119px;">A412-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sodium hydroxide</td>
			<td style="width:171px;">Amresco, USA</td>
			<td style="width:119px;">O583</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sodium dodecyl sulfate</td>
			<td style="width:171px;">Sigma, USA</td>
			<td style="width:119px;">L3371</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Bicinchoninic acid reagent</td>
			<td style="width:171px;">Sigma, USA</td>
			<td style="width:119px;">BCA1-1KT</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">UV-VIS Spectrophotometer</td>
			<td style="width:171px;">Pharmacia Biotech, NJ, USA</td>
			<td style="width:119px;">Ultrospec 2000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Normal chow diet</td>
			<td style="width:171px;">Labdiet.com</td>
			<td style="width:119px;">500I</td>
			<td>abreviated as NCD</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">C57BL/6 mice</td>
			<td style="width:171px;">Jackson Laboratory, CT, USA</td>
			<td style="width:119px;">Stock number000664</td>
			<td>wild type mice</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Parafilm</td>
			<td style="width:171px;">Heathrow Scientific, USA</td>
			<td style="width:119px;">HS 234526A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Glycerol standard</td>
			<td style="width:171px;">Sigma, USA</td>
			<td style="width:119px;">G7793</td>
			<td></td>
		</tr>
	</tbody>
</table>

measurement of basal and forskolin-stimulated lipolysis in inguinal adipose fat pads

Lipolysis is a process by which the lipid stored as triglycerides in adipose tissues are hydrolyzed into glycerol and fatty acids. This article describes the method for the measurement of basal and forskolin (FSK)-stimulated lipolysis in the inguinal fat pads isolated from wild type mice fed either normal chow diet (NCD), high fat diet (HFD) or a high fat diet containing 0.01% of capsaicin (CAP; transient receptor potential vanilloid subfamily 1 (TRPV1) agonist) for 32 weeks. The method described here for performing ex vivo lipolysis is adopted from Schweiger et al.1 We present a detailed protocol for measuring glycerol levels by UV-Visible (UV/VIS) spectrophotometry. The method described here can be used to successfully isolate inguinal fat pads for lipolysis measurements to obtain consistent results. The protocol described for inguinal fat pads can readily be extended to measure lipolysis in other tissues.

To evaluate the effect of CAP on basal and stimulated lipolysis, this research measured lipolysis in inguinal adipose fat pads isolated from NCD or HFD (&#177; CAP)-fed wild type mice. The representative results for the basal and FSK-stimulated lipolysis for the inguinal fat pads are given in Table I. Basal and FSK-stimulated glycerol release in the presence of Triacsin C, which inhibits acyl coA synthetase and prevents the regeneration of TGL. As shown in <strong class="...

Watch this Scientific Journal Video about Measurement of Basal and Forskolin-stimulated Lipolysis in Inguinal Adipose Fat Pads at JoVE.com

Measurement of Basal and Forskolin-stimulated Lipolysis in Inguinal Adipose Fat Pads

This protocol describes the method of determining basal and forskolin-stimulated lipolysis in inguinal fat pads obtained from normal chow diet (NCD) or high fat diet (HFD) &plusmn; capsaicin fed wild type mice. As an index for lipolysis, glycerol release was measured from inguinal adipose fat pads.

Lipolysis is a process by which the lipid stored as triglycerides in adipose tissues are hydrolyzed into glycerol and fatty acids. This article describes ...

The overall goal of this procedure is to measure basal and forskolin-stimulated lipolysis, using inguinal adipose tissue. This method can help answer key questions in field of adipose biology about lipolysis and triglyceride metabolism. The main advantage of this method is that it offers a direct, simple and cost-effective method to determine lipolysis in adipose tissues.Demonstrating the procedure will be Padmamalini Baskaran, who is a senior research scientist in my laboratory. Begin by placing the mouse on its left side on a dissecting platform. Sterilize the skin with a 2x2 inch gauze soaked in 70%ethanol and make a lateral cut through the skin to reveal the underlying fatty layer.Make a second one centimeter incision through the skin, below the ribs across the dorsal surface that connects with the first incision and use sterile forceps to slowly peel back the skin flap. The subcutaneous fat in the abdominal region is the inguinal fat, which is different from the subcutaneous fat around the upper arm, which demonstrates region specific lipolysis. Using a pair of scissors, carefully dissect the fat pad from the underlying muscle and fascia.Place the fat pad in a petri dish containing fresh, room temperature PBS and isolate the second fat pad. Using sharp scissors, cut the fat tissue into five to eight pieces and incubate the pieces in 200 microliters of incubation medium, at 37 degrees celsius and 5%carbon dioxide for 60 minutes. At the end of the incubation, transfer the supernatant into a new container for 80 degrees celsius for storage and transfer the fat pieces into one milliliter of extraction at 37 degrees centigrade, at 100 RPM.After one hour, discard the extraction solution and transfer the tissues into a sterile microfuge tube containing 500 microliters of lysis solution for an overnight incubation at 55 degrees centigrade and 100 RPM. Then determine the protein concentration of the tissue according to standard protocols. For forskolin-stimulated lipolysis, first, pre-incubate 20 milligrams of inguinal fat pad pieces isolated as just demonstrated.In 200 microliters of fresh DMEM, supplemented with BSA, forskolin and tricsin C at 37 degree celsius and 5%carbon dioxide. The addition of tricsin C inhibits a cyclase synthetase, which proves the regeneration of triglycerides from glycerol and free fatty acids. Thereby allowing for measurement of forskolin-stimulated lipolysis.After one hour, transfer the pieces into fresh DMEM, plus BSA, forskolin and tricsin C, for a second 60 minute incubation at 30 degree centigrade and 5%carbon dioxide. Collecting the supernatant at the end of the incubation for 80 degree celsius storage. Next, extract the fat from the tissue pieces with extraction solution is just demonstrated and transfer the tissue into a sterile microfuge tube containing 500 microliters of lysin solution for an overnight incubation at 55 degree celsius under vigorous shaking.Then, determine the protein concentration according to standard protocols. To determine the glycerol content of the samples, first, thaw the supernatants from 80 degrees centigrade on ice and dilute the samples to a one to 10 concentration in de-ionized water. Next add glycerol standards in ascending concentrations to one centimeter path length disposable methacrylate cuvettes per concentration and bring the final volume in each cuvette up to 10 microliters with de-ionized water.Add 10 microliters of each diluted sample into cuvettes labeled with the corresponding sample number and turn on the ultraviolet visible spectro photometer. Set the spectro photometer wavelength to 540 nanometers and add 10 microliters of each standard into a new series of standard cuvettes. Using a one milliliter pipette, add 8 milliliters of room temperature free glycerol reagent to each standard in sample cuvette and cover the cuvettes with a 1.5 centimeter square plastic paraffin film.Mix the contents in each cuvette with three inversions and allow the standards to equilibrate for 10 minutes at room temperature. Then, place each cuvette into the spectrophotometer and record the absorbents. In this table, represented of basal and forskolin-stimulated lipolysis of inguinal fat pads are shown.A high fat diet feeding has no effect on basal lipolysis, but demonstrates a significant suppression of forskolin-stimulated lipolysis. Capsaicin on the other hand, increases both basal and forskolin-stimulated lipolysis. Once mastered, this technique can be completed in two days if it is performed properly.While attempting this procedure, it is important to remember to use fat free BSA and while performing the procedure, not to shake or invert the samples to prevent air bubbles. After each level have met, this method paved the way for researchers in the field of adipose biology for measuring lipolysis in adipose tissues in rodent models of obesity. After watching this video, you should have a good understanding of how to determine basal and forskolin=stimulated lipolysis in inguinal white adipose tissues.Don't forget, working with a glycerol reagent can be unstable and how the reagent is stored and the lifetime of the reagent should be considered while working with it.

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Research

JoVE Journal

Biochemistry

Preparation of Keratin Hydrolysate from Chicken Feathers and Its Application in Cosmetics

Keratin hydrolysates (KHs) are established standard components in hair cosmetics. Understanding the moisturizing effects of KH is advantageous for skin-care cosmetics. The goals of the protocol are: (1) to process chicken feathers into KH by alkaline-enzymatic hydrolysis and purify it by dialysis, and (2) to test if adding KH into an ointment base (OB) increases hydration of the skin and improves skin barrier function by diminishing transepidermal water loss (TEWL). During alkaline-enzymatic hydrolysis feathers are first incubated at a higher temperature in an alkaline environment and then, under mild conditions, hydrolyzed with proteolytic enzyme. The solution of KH is dialyzed, vacuum dried, and milled to a fine powder. Cosmetic formulations comprising from oil in water emulsion (O/W) containing 2, 4, and 6 weight% of KH (based on the weight of the OB) are prepared. Testing the moisturizing properties of KH is carried out on 10 men and 10 women at time intervals of 1, 2, 3, 4, 24, and 48 h. Tested formulations are spread at degreased volar forearm sites. The skin hydration of stratum corneum (SC) is assessed by measuring capacitance of the skin, which is one of the most world-wide used and simple methods. TEWL is based on measuring the quantity of water transported per a defined area and period of time from the skin. Both methods are fully non-invasive. KH makes for an excellent occlusive; depending on the addition of KH into OB, it brings about a 30% reduction in TEWL after application. KH also functions as a humectant, as it binds water from the lower layers of the epidermis to the SC; at the optimum KH addition in the OB, up to 19% rise in hydration in men and 22% rise in women occurs.

The goal of the protocol is to prepare keratin hydrolysate from chicken feathers by alkaline-enzymatic hydrolysis and to test whether adding keratin hydrolysate into a cosmetics ointment base improves skin barrier function (heightening hydration and diminishing transepidermal water loss). Tests are conducted on men and woman volunteers.

Keratin hydrolysates (KHs) are established standard components in hair cosmetics. Understanding the moisturizing effects of KH is advantageous for ...

Isolation and Respiratory Measurements of Mitochondria from Arabidopsis thaliana

Mitochondria are essential organelles involved in numerous metabolic pathways in plants, most notably the production of adenosine triphosphate (ATP) from the oxidation of reduced compounds such as nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FADH2). The complete annotation of the Arabidopsis thaliana genome has established it as the most widely used plant model system, and thus the need to purify mitochondria from a variety of organs (leaf, root, or flower) is necessary to fully utilize the tools that are now available for Arabidopsis to study mitochondrial biology. Mitochondria are isolated by homogenization of the tissue using a variety of approaches, followed by a series of differential centrifugation steps producing a crude mitochondrial pellet that is further purified using continuous colloidal density gradient centrifugation. The colloidal density material is subsequently removed by multiple centrifugation steps. Starting from 100 g of fresh leaf tissue, 2 - 3 mg of mitochondria can be routinely obtained. Respiratory experiments on these mitochondria display typical rates of 100 - 250 nmol O2 min-1 mg total mitochondrial protein-1 (NADH-dependent rate) with the ability to use various substrates and inhibitors to determine which substrates are being oxidized and the capacity of the alternative and cytochrome terminal oxidases. This protocol describes an isolation method of mitochondria from Arabidopsis thaliana leaves using continuous colloidal density gradients and an efficient respiratory measurements of purified plant mitochondria.

Isolation and Respiratory Measurements of Mitochondria from Arabidopsis thaliana

As mitochondria are only a small percentage of the plant cell, they need to be purified for a range of studies. Mitochondria can be isolated from a variety of plant organs by homogenization, followed by differential and density gradient centrifugation to obtain a highly purified mitochondrial fraction.

Mitochondria are essential organelles involved in numerous metabolic pathways in plants, most notably the production of adenosine triphosphate (ATP) from ...

Simultaneous Measurement of Superoxide/Hydrogen Peroxide and NADH Production by Flavin-containing Mitochondrial Dehydrogenases

It has been reported that mitochondria can contain up to 12 enzymatic sources of reactive oxygen species (ROS). A majority of these sites include flavin-dependent respiratory complexes and dehydrogenases that produce a mixture of superoxide (O2&#9679;-) and hydrogen peroxide (H2O2). Accurate quantification of the ROS-producing potential of individual sites in isolated mitochondria can be challenging due to the presence of antioxidant defense systems&#160;and side reactions that also form O2&#9679;-/H2O2. Use&#160;of nonspecific inhibitors that can disrupt mitochondrial bioenergetics can also compromise measurements by altering&#160;ROS release from other sites of production. Here, we present an easy method for the simultaneous measurement of H2O2 release and nicotinamide adenine dinucleotide (NADH) production by purified flavin-linked dehydrogenases. For our purposes here, we have used purified pyruvate dehydrogenase complex (PDHC) and &#945;-ketoglutarate dehydrogenase complex (KGDHC) of porcine heart origin as examples. This method allows for an accurate measure of native H2O2 release rates by individual sites of production by eliminating other potential sources of ROS and antioxidant systems. In addition, this method allows for a direct comparison of the relationship between H2O2 release and enzyme activity and the screening of the effectiveness and selectivity of inhibitors for ROS production. Overall, this approach can allow for the in-depth assessment of native rates of ROS release for individual enzymes prior to conducting more sophisticated experiments with isolated mitochondria or permeabilized muscle fiber.

Mitochondria contain several flavin-dependent enzymes that can produce reactive oxygen species (ROS). Monitoring ROS release from individual sites in mitochondria is challenging due to unwanted side reactions. We present an easy, inexpensive method for direct assessment of native rates for ROS release using purified flavoenzymes and microplate fluorometry.

It has been reported that mitochondria can contain up to 12 enzymatic sources of reactive oxygen species (ROS). A majority of these sites include ...

Mouse Adipose Tissue Collection and Processing for RNA Analysis

Compared to other tissues, white adipose tissue has a considerably less RNA and protein content for downstream applications such as real-time PCR and Western Blot, since it mostly contains lipids. RNA isolation from adipose tissue samples is also challenging as extra steps are required to avoid these lipids. Here, we present a procedure to collect three anatomically different white adipose tissues from mice, to process these samples and perform RNA isolation. We further describe the synthesis of cDNA and gene expression experiments using real-time PCR. The hereby described protocol allows the reduction of contamination from the animal's hair and blood on fat pads as well as cross-contamination between different fat pads during tissue collection. It has also been optimized to ensure adequate quantity and quality of the RNA extracted. This protocol can be widely applied to any mouse model where adipose tissue samples are required for routine experiments such as real-time PCR but is not intended for isolation from primary adipocytes cell culture.

The purpose of this paper is to present a step-by-step procedure to collect different white adipose tissues from mice, process the fat samples and extract RNA.

Compared to other tissues, white adipose tissue has a considerably less RNA and protein content for downstream applications such as real-time PCR and ...

Measurement of Mitochondrial Oxygen Consumption in Permeabilized Fibers of Drosophila Using Minimal Amounts of Tissue

The fruit fly, Drosophila melanogaster, represents an emerging model for the study of metabolism. Indeed, drosophila have structures homologous to human organs, possess highly conserved metabolic pathways and have a relatively short lifespan that allows the study of different fundamental mechanisms in a short period of time. It is, however, surprising that one of the mechanisms essential for cellular metabolism, the mitochondrial respiration, has not been thoroughly investigated in this model. It is likely because the measure of the mitochondrial respiration in Drosophila usually requires a very large number of individuals and the results obtained are not highly reproducible. Here, a method allowing the precise measurement of mitochondrial oxygen consumption using minimal amounts of tissue from Drosophila is described. In this method, the thoraxes are dissected and permeabilized both mechanically with sharp forceps and chemically with saponin, allowing different compounds to cross the cell membrane and modulate the mitochondrial respiration. After permeabilization, a protocol is performed to evaluate the capacity of the different complexes of the electron transport system (ETS) to oxidize different substrates, as well as their response to an uncoupler and to several inhibitors. This method presents many advantages compared to methods using mitochondrial isolations, as it is more physiologically relevant because the mitochondria are still interacting with the other cellular components and the mitochondrial morphology is conserved. Moreover, sample preparations are faster, and the results obtained are highly reproducible. By combining the advantages of Drosophila as a model for the study of metabolism with the evaluation of mitochondrial respiration, important new insights can be unveiled, especially when the flies are experiencing different environmental or pathophysiological conditions.

In this paper, a method to measure oxygen consumption using high-resolution respirometry in permeabilized thoraxes of Drosophila is described. This technique requires a minimal amount of tissue compared to the classic mitochondrial isolation technique and the results obtained are more physiologically relevant.

The fruit fly, Drosophila melanogaster, represents an emerging model for the study of metabolism. Indeed, drosophila have structures homologous to human ...

In Situ Measurement and Correlation of Cell Density and Light Emission of Bioluminescent Bacteria

There is a considerable number of bacterial species capable of emitting light. All of them share the same gene cluster, namely the lux operon. Despite this similarity, these bacteria show extreme variations in characteristics like growth behavior, intensity of light emission or regulation of bioluminescence. The method presented here is a newly developed assay that combines recording of cell growth and bioluminescent light emission intensity over time utilizing a plate reader. The resulting growth and light emission characteristics can be linked to important features of the respective bacterial strain, such as quorum sensing regulation. The cultivation of a range of bioluminescent bacteria requires a specific medium (e.g., artificial sea water medium) and defined temperatures. The easy to handle, non-bioluminescent standard-research bacterium Escherichia coli (E. coli), on the other hand, can be cultivated inexpensively in high quantities in laboratory scale. Exploiting E. coli by introducing a plasmid containing the whole lux operon can simplify experimental conditions and additionally opens up many possibilities for future applications. The expression of all lux genes utilizing an E. coli expression strain was achieved by construction of an expression plasmid via Gibson cloning and insertion of four fragments containing seven lux genes and three rib genes of the lux-rib operon into a pET28a vector. E. coli based lux gene expression can be induced and controlled via Isopropyl-&#946;-D-thiogalactopyranosid (IPTG) addition resulting in bioluminescent E. coli cells. The advantages of this system are to avoid quorum sensing regulation restrictions and complex medium compositions along with non-standard growth conditions, such as defined temperatures. This system enables analysis of lux genes and their interplay, by the exclusion of the respective gene from the lux operon, or even addition of novel genes, exchanging the luxAB genes from one bacterial strain by another, or analyzing protein complexes, such as luxCDE.

In Situ Measurement and Correlation of Cell Density and Light Emission of Bioluminescent Bacteria

Bioluminescent bacteria regulate light production through a variety of mechanisms, such as quorum sensing. This novel method allows the in situ investigation of bioluminescence and the correlation of light emission to cell density. An artificial bioluminescent Escherichia coli system allows the characterization of lux operons, Lux proteins, and their interplay.

There is a considerable number of bacterial species capable of emitting light. All of them share the same gene cluster, namely the lux operon. Despite ...

Cortisol Measurement in Koala (Phascolarctos cinereus) Fur

Optimal methods of hormone extraction used to measure stress in animals across sample types are not always the same. Australia&#39;s iconic marsupial species, the koala (Phascolarctos cinereus), faces prolonged exposure to anthropogenic-induced stressors and assessment of chronic stress in wild populations is urgently warranted. One of the most effective ways to measure chronic stress is through analyzing the glucocorticoid hormone cortisol in hair or fur, as it supports physiological and behavioral responses. This laboratory validation study aims to test current techniques to validate an optimal hormone extraction method to be used as a non-invasive measure of cortisol in koala fur. It is recognized that using non-invasive techniques to measure stress hormones is preferred over traditional, invasive techniques due to their ideal practical and ethical standpoints. Additionally, it is comparatively easier to acquire fur from koalas than it is to acquire samples of their blood. This study used samples of koala fur acquired from the Adelaide Koala and Wildlife Hospital to run a number of hormone extraction techniques in an attempt to validate an optimal cortisol extraction method. Results showed that 100% methanol provided the most optimal solvent extraction compared to 100% ethanol or 100% isopropanol based on parallelism results. In conclusion, this method of cortisol extraction from koala fur provided a reliable non-invasive assay that could be used to study chronic stress in koalas.

Cortisol Measurement in Koala Phascolarctos cinereus Fur

We present a protocol to determine the optimal extraction solvent to measure cortisol from koala fur. The solvents used in this protocol are methanol, ethanol and isopropanol. Determining an optimal extraction solvent will aid in reliably measuring fur to determine the impact of chronic stress on koalas.

Optimal methods of hormone extraction used to measure stress in animals across sample types are not always the same. Australia&#39;s iconic marsupial ...

Measurement of Fatty Acid &#946;-Oxidation in a Suspension of Freshly Isolated Mouse Hepatocytes

Fatty acid &#946;-oxidation is a key metabolic pathway to meet the energy demands of the liver and provide substrates and cofactors for additional processes, such as ketogenesis and gluconeogenesis, which are essential to maintain whole-body glucose homeostasis and support extra-hepatic organ function in the fasted state. Fatty acid &#946;-oxidation occurs within the mitochondria and peroxisomes and is regulated through multiple mechanisms, including the uptake and activation of fatty acids, enzyme expression levels, and availability of cofactors such as coenzyme A and NAD+. In assays that measure fatty acid &#946;-oxidation in liver homogenates, cell lysis and the common addition of supraphysiological levels of cofactors mask the effects of these regulatory mechanisms. Furthermore, the integrity of the organelles in the homogenates is hard to control and can vary significantly between preparations. The measurement of fatty acid &#946;-oxidation in intact primary hepatocytes overcomes the above pitfalls. This protocol describes a method for the measurement of fatty acid &#946;-oxidation in a suspension of freshly isolated primary mouse hepatocytes incubated with 14C-labeled palmitic acid. By avoiding hours to days of culture, this method has the advantage of better preserving the protein expression levels and metabolic pathway activity of the original liver, including the activation of fatty acid &#946;-oxidation observed in hepatocytes isolated from fasted mice compared to fed mice.

Measurement of Fatty Acid &amp;#946;-Oxidation in a Suspension of Freshly Isolated Mouse Hepatocytes

Fatty acid &#946;-oxidation is an essential metabolic pathway responsible for generating energy in many different cell types, including hepatocytes. Here, we describe a method to measure fatty acid &#946;-oxidation in freshly isolated primary hepatocytes using 14C-labeled palmitic acid.

Fatty acid &#946;-oxidation is a key metabolic pathway to meet the energy demands of the liver and provide substrates and cofactors for additional ...

Measurement of Protein Import Capacity of Skeletal Muscle Mitochondria

Mitochondria are key metabolic and regulatory organelles that determine the energy supply as well as the overall health of the cell. In skeletal muscle, mitochondria exist in a series of complex morphologies, ranging from small oval organelles to a broad, reticulum-like network. Understanding how the mitochondrial reticulum expands and develops in response to diverse stimuli such as alterations in energy demand has long been a topic of research. A key aspect of this growth, or biogenesis, is the import of precursor proteins, originally encoded by the nuclear genome, synthesized in the cytosol, and translocated into various mitochondrial sub-compartments. Mitochondria have developed a sophisticated mechanism for this import process, involving many selective inner and outer membrane channels, known as the protein import machinery (PIM). Import into the mitochondrion is dependent on viable membrane potential and the availability of organelle-derived ATP through oxidative phosphorylation. Therefore its measurement can serve as a measure of organelle health. The PIM also exhibits a high level of adaptive plasticity in skeletal muscle that is tightly coupled to the energy status of the cell. For example, exercise training has been shown to increase import capacity, while muscle disuse reduces it, coincident with changes in markers of mitochondrial content. Although protein import is a critical step in the biogenesis and expansion of mitochondria, the process is not widely studied in skeletal muscle. Thus, this paper outlines how to use isolated and fully functional mitochondria from skeletal muscle to measure protein import capacity in order to promote a greater understanding of the methods involved and an appreciation of the importance of the pathway for organelle turnover in exercise, health, and disease.

Mitochondria are key metabolic organelles that exhibit a high level of phenotypic plasticity in skeletal muscle. The import of proteins from the cytosol is a critical pathway for organelle biogenesis, essential for the expansion of the reticulum and the maintenance of mitochondrial function. Therefore, protein import serves as a barometer of cellular health.

Mitochondria are key metabolic and regulatory organelles that determine the energy supply as well as the overall health of the cell. In skeletal muscle, ...

Measurement of Protein Turnover Rates in Senescent and Non-Dividing Cultured Cells with Metabolic Labeling and Mass Spectrometry

Mounting evidence has shown that the accumulation of senescent cells in the central nervous system contributes to neurodegenerative disorders such as Alzheimer&#39;s and Parkinson&#39;s diseases. Cellular senescence is a state of permanent cell cycle arrest that typically occurs in response to exposure to sub-lethal stresses. However, like other non-dividing cells, senescent cells remain metabolically active and carry out many functions that require unique transcriptional and translational demands and widespread changes in the intracellular and secreted proteomes. Understanding how protein synthesis and decay rates change during senescence can illuminate the underlying mechanisms of cellular senescence and find potential therapeutic avenues for diseases exacerbated by senescent cells. This paper describes a method for proteome-scale evaluation of protein half-lives in non-dividing cells using pulsed stable isotope labeling by amino acids in cell culture (pSILAC) in combination with mass spectrometry. pSILAC involves metabolic labeling of cells with stable heavy isotope-containing versions of amino acids. Coupled with modern mass spectrometry approaches, pSILAC enables the measurement of protein turnover of hundreds or thousands of proteins in complex mixtures. After metabolic labeling, the turnover dynamics of proteins can be determined based on the relative enrichment of heavy isotopes in peptides detected by mass spectrometry. In this protocol, a workflow is described for the generation of senescent fibroblast cultures and similarly arrested quiescent fibroblasts, as well as a simplified, single-time point pSILAC labeling time-course that maximizes coverage of anticipated protein turnover rates. Further, a pipeline is presented for the analysis of pSILAC mass spectrometry data and user-friendly calculation of protein degradation rates using spreadsheets. The application of this protocol can be extended beyond senescent cells to any non-dividing cultured cells such as neurons.

This protocol describes the workflow for metabolic labeling of senescent and non-dividing cells with pulsed SILAC, untargeted mass spectrometry analysis, and a streamlined calculation of protein half-lives.

Mounting evidence has shown that the accumulation of senescent cells in the central nervous system contributes to neurodegenerative disorders such as ...