This research was supported in part by NSF grant CHE-1229562 (VDGM), the Office of Undergraduate Research at Elon University, the Elon Chemistry Department, and the Elon Lumen Prize (TL and TAD), the Elon College Fellows Program (JAC), and the Elon College Honors Program (TAD).

All animal experiments conformed to National Institutes of Health guidelines and were approved by the Wake Forest University Animal Care and Use Committee. Breeding pairs for SOD1G93A [B6SJL-TgN (SOD1-G93A) 1Gur] mouse model were obtained from The Jackson Laboratory (Bar Harbor, ME). Nontransgenic wild-type (WT) females and SOD1G93A males [B6SJL-TgN (SOD1-G93A) 1Gur] were bred to generate SOD1G93A mice and nontransgenic WT littermates that were used in the experiments.
1. Models for Investigatio...

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The authors have nothing to disclose.

Treatment of HEK-293T cells with recombinant cytokines causes moderate amounts of cell death over 48 hr (Figure 1). The amount of cell death induced by TNF-alpha treatment is similar to previously reported studies30 and cell viability decreases after co-administration of multiple cytokines that are greater than summative amounts with any cytokine alone is also consistent with the literature31,32. The ability to adjust the amounts and types of cytokine treatments as well as compariso...

Living cells bank metabolic energy in the form of fats and carbohydrates and use this energy for biosynthesis, membrane transport and movement. Some energy is obtained in the cytosol through the conversion of dietary sugars directly into ATP during glycolysis. However, the main source of ATP production in a cell is harnessed within the mitochondria via the mitochondrial respiratory chain1. The architecture of mitochondria provides the necessary spatial orientation for effective and efficient ATP production. Mitochondria possess a double membrane separated by an intermembrane space and together with the matrix, the innermost mitochondrial compartment, house the components and coordinate the chemical reactions involved in ATP generation. The inner membrane contains a series of membrane-bound protein complexes that comprise the respiratory chain as well as the ATP synthase, the protein complex that brings ADP and Pi together for formation of ATP. The inner membrane is folded into cristae and electrons are passed along the respiratory chain complexes via cytochrome c, a soluble electron carrier which moves between complexes within the intermembrane space. As electrons move, oxidation of reducing equivalents occurs and hydrogen ions are pumped from the matrix to the intermembrane space. As a consequence of the high ion concentration within the intermembrane space, an electrochemical gradient builds resulting in a membrane potential across the inner mitochondrial membrane (&#8710;&#968;)2. Oxygen is the final electron acceptor of the electron transport chain, and hydrogen ions flow through the ATP synthases from the intermembrane space back to the matrix, and in doing so directly cause ATP formation. This process as described in its entirety is known as oxidative phosphorylation. The folds of the cristae increase the surface area of the inner membrane, allowing for maximal electron transport and ATP production within each mitochondrion. The proteins, enzymes and other molecules involved in oxidative phosphorylation are derived from both nuclear and mitochondrial genes. Mitochondria contain their own circular DNA, encoding for 13 proteins as well as tRNAs and mRNAs necessary for ATP production3. However, many more proteins are required and thus are nuclear encoded. Most of these nuclear-encoded proteins are targeted to the mitochondrial matrix by the use of presequences at the N-terminus of the precursor protein, and their import is driven in part by &#8710;&#968;4,5.
Beyond contributing to the bioenergetics of a cell, mitochondria also influence major metabolic processes such as TCA and beta-oxidation, cellular signaling through regulating calcium, as well as a key role in apoptosis6. Specifically, during times of cellular stress, BCL-2 family proteins that reside on or interact at the mitochondrial outer membrane can cause mitochondrial outer membrane permeability (MOMP)7,8. During MOMP, cytochrome c and other proteins are released into the cytosol, and together with several cytosolic proteins form a complex called the apoptosome9,10. The apoptosome activates caspases that go on to cleave cellular proteins and DNA during the execution phase of apoptosis. As soon as MOMP occurs, &#8710;&#936; is collapsed and ATP production halted. Thus, as apoptosis is initiated mitochondrial function is compromised and changes in &#8710;&#936; can be correlated to mitochondrial and cell health12. While apoptosis is an endpoint in many disease models, mitochondrial function and changes to &#8710;&#936; can also yield valuable information about disease origination and/or progression. For instance, mitochondrial structural and functional changes have been documented during the course of neurodegenerative diseases13,14.
In the first part of the protocol, isolation of intact mitochondria that retain their &#916;&#936; is described. HEK-293T cells were exposed to different concentrations and combinations of recombinant TNF-&#945;, IL1-&#946; and IFN-&#947; to induce apoptosis. These cytokines were chosen because they are frequently reported to be high in primary human septic samples15 and the extrinsic pathway of apoptosis can be triggered by interaction of TNF-&#945; binding to its receptor6 . Since there are subtle variations necessary to isolate functional mitochondria from primary tissues as compared to cultured cells, and because much research utilizes animals, the protocol also describes how to isolate mitochondria from liver and spinal cords of anterior lateral sclerosis (ALS) mouse model.
The second part of the protocol was developed to monitor perturbations to the mitochondrial membrane potential using a potential-sensitive fluorescent dye with a fluorescent plate reader. Differences between cellular status (i.e., healthy vs. unhealthy) are differentiated by quantitating the strength of &#916;&#936; of isolated mitochondria in conjunction with uncoupling agents, respiratory chain inhibitors, complex inhibitors and ionophores, all of which cause dissipation of the mitochondrial membrane potential. The healthier the mitochondria, the larger the change in &#8710;&#936; upon treatment with mitochondrial inhibitors, therefore the response of mitochondria can be used as an indicator of mitochondrial (dys)function.
Use of isolated mitochondria rather than in situ assessment of function offers definitive evidence that a pathology or treatment directly modulates changes to the organelle16-18. While there are methods in the literature to isolate mitochondria from cultured cells, they are vague17 and/or utilize specialized equipment16. This protocol describes in detail the isolation method and is readily adaptable to other cell lines, including primary tissue and cultures13,14,19,20. Many isolated mitochondria studies utilize the same mitochondrial uncouplers and inhibitors used in this protocol but with a Clark electrode (21 is a representative example of many papers in the literature), which again is a very specific and specialized piece of equipment. Furthermore, this traditional method has limitations such as low throughput and high complexity22,23 and requires a substantial amount of mitochondria (~500 &#181;g/reaction). In this protocol, the fluorescent membrane-sensing potential probe TMRE is used in conjunction with a fluorescent plate reader, which is a standard machine in many laboratories. TMRE is widely regarded since it quickly enters cells and isolated mitochondria and can be used at low concentrations24. Multiple reactions can quickly be set up in tandem and batch analyzed using this protocol. Furthermore, the reactions require a much small amount of isolated mitochondria (~10 &#181;g/reaction). By requiring less material, smaller tissue or cell culture samples can be utilized as a starting point for mitochondria isolation, more replicates or reactions can be set up, and potentially enough material for other isolated mitochondria experiments such as ATP production, oxygen consumption, or import assays are possible.

<table border="0" cellpadding="0" cellspacing="0" width="686">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:209px;">Name of Material/ Equipment</td>
			<td style="width:137px;">Company</td>
			<td style="width:163px;">Catalog Number</td>
			<td style="width:179px;">Comments/Description</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">L-glutamic acid</td>
			<td>Sigma</td>
			<td>G1251</td>
			<td>Can use the potassium salt instead.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">malic acid</td>
			<td>Sigma</td>
			<td>M8304</td>
			<td>Can use the potassium salt instead.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">KH2PO4</td>
			<td>Sigma</td>
			<td>P0662</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">K2HPO4</td>
			<td>Sigma</td>
			<td>P3786</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">EGTA</td>
			<td>Sigma</td>
			<td>E3889</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Trisma base</td>
			<td>Sigma</td>
			<td>T6066</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">MOPS</td>
			<td>Sigma</td>
			<td>M3183</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">CCCP</td>
			<td>Sigma</td>
			<td>C2920</td>
			<td>Dilute down to 100uM as a working stock in ethanol and store at -20C.&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Valinomycin</td>
			<td>Sigma</td>
			<td>V0627</td>
			<td>Make in DMSO and use as a 5uM working stock. Store at -20C.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">sucrose</td>
			<td>Fisher</td>
			<td>S5-500</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">KCN</td>
			<td>Mallinckrodt</td>
			<td align="right">6379</td>
			<td>Make a concentrated stock in ethanol and then dilute with water&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">rotenone</td>
			<td>Sigma</td>
			<td>R8875</td>
			<td>Highly toxic. Made in ethanol.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">oligomycin</td>
			<td>Sigma</td>
			<td>O4876</td>
			<td>Highly toxic. Made in ethanol.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">ADP</td>
			<td>Sigma</td>
			<td>A2754</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">TMRE</td>
			<td>Sigma</td>
			<td>8717-25mg</td>
			<td>Dilute 100uM stock with EB immediatley before use.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">DMEM</td>
			<td>Gibco</td>
			<td>11965-084</td>
			<td>1x regular (high glucose).</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Pen/Strep</td>
			<td>Invitrogen</td>
			<td>15140-155</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">L-glutamine</td>
			<td>Fisher</td>
			<td>SH3002101</td>
			<td>Store aliquots at -20C</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">FBS</td>
			<td>Lonza</td>
			<td>14-501F</td>
			<td>US origin, premium quality. Heat inactivate and store aliquots at -20</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Trypsin-EDTA</td>
			<td>Sigma</td>
			<td>T4049</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">DMSO</td>
			<td>SIgma</td>
			<td>D2650</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:209px;">Protien Assay Dye (5x)</td>
			<td style="width:137px;">Bio-Rad</td>
			<td style="width:163px;">500-0006</td>
			<td>Any protein assay can substitute.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:209px;">BSA</td>
			<td style="width:137px;">Fisher</td>
			<td style="width:163px;">BP1600-100</td>
			<td>Make 2mg/mL stock in water for protein assay.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">MTT powder</td>
			<td>Sigma</td>
			<td>M2128</td>
			<td>Filter sterlize 5mg/mL stock made in PBS. Store aliquots at -20C; store at 4C for up to 1 week.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Tergitol solution (NP-40)</td>
			<td>Sigma</td>
			<td>NP40S</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Recombinant Human IL-1B</td>
			<td>Gibco</td>
			<td>PCH08014</td>
			<td>Once opened store aliquots at -20C</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Recombinant Human TNF-alpha</td>
			<td>Gibco</td>
			<td>PHC3015L</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Recombinant Human IFN-gamma</td>
			<td style="width:137px;">Gibco</td>
			<td>PHC4031</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:209px;">Dulbeccos PBS (-/-)</td>
			<td>Sigma</td>
			<td style="width:163px;">D8537</td>
			<td>Make sure it is without Mg2+ and Ca2+ ions.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Cytochrom c ELISA kit</td>
			<td>R&#38;D systems</td>
			<td>DTC0</td>
			<td>Human for HEK-293T cells.&#160;</td>
		</tr>
	</tbody>
</table>

isolation and functional analysis of mitochondria from cultured cells and mouse tissue

Comparison between two or more distinct groups, such as healthy vs. disease, is necessary to determine cellular status. Mitochondria are at the nexus of cell heath due to their role in both cell metabolism and energy production as well as control of apoptosis. Therefore, direct evaluation of isolated mitochondria and mitochondrial perturbation offers the ability to determine if organelle-specific (dys)function is occurring. The methods described in this protocol include isolation of intact, functional mitochondria from HEK cultured cells and mouse liver and spinal cord, but can be easily adapted for use with other cultured cells or animal tissues. Mitochondrial function assessed by TMRE and the use of common mitochondrial uncouplers and inhibitors in conjunction with a fluorescent plate reader allow this protocol not only to be versatile and accessible to most research laboratories, but also offers high throughput.

Treatment of HEK-293T cells with 200 pg/ml TNF-&#945;, 40 ng/ml IL1-&#946;, and 75 ng/ml IFN-&#947; (*3) for 24-48 hr leads to progressive amounts of cell death (Figure 1A). Cell viability was assessed using MTT assays and consistently demonstrates that there is ~10% decrease in cell viability with 24 hr treatment and ~20% decrease with 48 hr treatment. Cells treated with similar concentrations (100 pg/ml TNF-&#945;, 40 ng/ml IL1-&#946;, and 75 ng/ml IFN-&#947;) yield similar cell death results at 48 hr,...

Watch this Scientific Journal Video about Isolation and Functional Analysis of Mitochondria from Cultured Cells and Mouse Tissue at JoVE.com

Isolation and Functional Analysis of Mitochondria from Cultured Cells and Mouse Tissue

Comparison of mitochondrial membrane potential between samples yields valuable information about cellular status. Detailed steps for isolating mitochondria and assessing response to inhibitors and uncouplers using fluorescence are described. The method and utility of this protocol are illustrated by use of a cell culture and animal model of cellular stress.

Comparison between two or more distinct groups, such as healthy vs. disease, is necessary to determine cellular status. Mitochondria are at the nexus of ...

isolation-functional-analysis-mitochondria-from-cultured-cells-mouse

Research

JoVE Journal

Biology

39.0K visualizações.  Elon University. Comparison of mitochondrial membrane potential between samples yields valuable information about cellular status. Detailed steps for isolating mitochondria and assessing response to inhibitors and uncouplers using fluorescence are described. The method and utility of this protocol are illustrated by use of a cell culture and animal model of cellular stress. 