Name: mitochondrial ca2+ retention capacity assay and ca2+-triggered mitochondrial swelling assay
Uploaded: 2018-05-01T12:30:00.000+00:00
Duration: 5 min 53 s
Description: Watch this Scientific Journal Video about Mitochondrial Ca2+ Retention Capacity Assay and Ca2+-triggered Mitochondrial Swelling Assay at JoVE.com

本研究は、山東省卓越した科学者 (JQ201421) と NSFC (81371226) からの助成金の助成金からの助成金によって支えられました。

1. ミトコンドリアの分離
注: すべてのソリューションや機器 0 - 4 ° C に冷却、氷で保たれます。
<ol><li>10 cm 細胞培養ディッシュあたり種子約 3 x 10 の6 SH SY5Y 細胞。高グルコース ダルベッコの培養細胞の 10% 牛胎児血清ペニシリン (100 U/mL) とイーグル培地、変更された-ストレプトマイシン (100 μ g/mL)。一晩 5% CO2を含むインキュベーターで 37 ° C で維持します。 注: 少なくとも 1-2 107 SH SY5Y セル x は各分離アッセイに必要な。</li>
	<li>メディアを取り出して、3 回約 1 ml の 10 cm 細胞培養皿で氷冷 PBS のセルを洗浄します。</li>
	<li>10 cm 細胞培養皿に氷冷 PBS の新しい 1 mL を追加し、新しい 1.5 mL チューブに付着性のセルをこすり。800 x g で 4 ° C で 10 分間遠心</li>
	<li>、遠心分離中にプロテアーゼ阻害剤在庫の 50 μ L を添加した 5 mL ミトコンドリア分離バッファー (250 mM ショ糖、10 mM HEPES (4-(2-hydroxyethyl) 1 ピペラジン ethanesulfonic 酸), 10 mM KCl, 1.5 mM MgCl2、1 mM EDTA) の準備します。(100 倍の濃度; ddH2O の 500 μ L に溶解し 1 EDTA 無料タブレット) のソリューションです。</li>
	<li>上澄みを除去し、ミトコンドリア分離バッファーの 1 mL にペレットを再懸濁します。30 分間氷の上 1.5 mL チューブを孵化させなさい。</li>
	<li>上下に手動で氷の上ガラス ホモジナイザー (15-25 ストローク) と浮遊細胞を溶解します。 注: 細胞をホモジナイズ時に気泡がないことを確認します。視覚的に顕微鏡でそのままなセルとむく核をカウントし、ことを確認 > 90% 細胞破砕が発生しました。</li>
	<li>1.5 mL チューブと (核と残りのままなセル) の残骸を削除する 4 ° C で 5 分間 1,000 × g で遠心分離機に磨砕液を転送します。</li>
	<li>新しい 1.5 mL チューブに 1,000 x g で 5 分間遠心上清を転送 4 ° C</li>
	<li>上清を新しいチューブと 14,000 × g で 15 分間遠心するに転送 4 ° C</li>
	<li>上澄みを除去し、ミトコンドリア ミトコンドリア分離バッファーの 1 つの mL を含むペレットを再懸濁します。</li>
	<li>14,000 x g 4 ° C で 15 分のためのソリューションを遠心分離機、ミトコンドリアを沈殿させます。</li>
	<li>結果ミトコンドリア ペレットを氷で冷やして、50-100 お尻の前にペレットの量に応じて KCl メディアを μ L (125 mM KCl、2 ミリメートル K2HPO4、1 mM MgCl2、20 mM HEPES、5 mM グルタミン酸 5 mM マラテと 2 μ M ロテノン、pH 7.4) で再停止される必要があります。そう。</li>
	<li>標準 BCA アッセイ、OD562 を測定によってミトコンドリア蛋白質の集中を測定するミトコンドリア ソリューションの 5 μ L を使用してプレート リーダー13を使用して。</li>
</ol>2. ミトコンドリアの Ca2 +の保持容量の決定
<ol><li>KCl メディアを準備し、Ca2 +を追加-実験前に 0.5 μ M の最終的な集中に緑色の蛍光色素を結合します。</li>
	<li>0.5 μ M の Ca2 +を含む KCl メディア分離ミトコンドリア (0.4 mg/mL) の 1 mL を転送-よく各 6 ウェル プレートに緑色の蛍光色素を結合します。</li>
	<li>ミトコンドリアと Ca2 +を孵化させなさい-室温 20 mm CaCl2ソリューション (20 mM CaCl2, 127 mM KCl、1 mM MgCl2 1 分追加 4 μ 因数の周囲の光から保護 6 ウェル プレートで緑の蛍光色素を結合、20 mM HEPES、グルタミン酸 5 mM、5 mM のリンゴ酸、pH 7.4) 各 6 ウェル プレートに自動を使用してよく分配設定 200 nmol Ca2 +/mg ミトコンドリア蛋白質を紹介します。</li>
	<li>蛍光分析装置を使用するには、すべて 3 蛍光の変化を監視して s 励起波長 506 の 2 分を nm、発光波長 531 nm。プレートは 3 の 600 rpm で揺れ装備ソフトウェア (図 1) によって制御の測定値間の s。</li>
	<li>各ウェルに 20 mM CaCl2ソリューションの追加 4 μ 因数を追加し、すべての 3 の蛍光の変化を監視 2 分の s は、蛍光性は時間とともに増加するまでこの手順を繰り返します。 注: ミトコンドリアと追加された Ca2 +増加記録蛍光によって示される挑戦されています。MPTP が開いたら、蛍光性は時間とともに増加します。</li>
	<li>Ca2 +追加 Ca2 +保持能力として、mPTP が開くまでの総額を解釈します。</li>
</ol>3. Ca 2 +の定量-ミトコンドリアの膨潤を誘発
<ol><li>実験前に KCl メディアを準備します。<ol>
<li>KCl メディアでの分離ミトコンドリア (0.4 mg/mL) の 1 つの mL を各 6 ウェル プレートにも転送します。</li>
	</ol>
</li>
	<li>ミトコンドリアの膨潤をトリガーするミトコンドリアのタンパク質に 10 μ L の 20 mM CaCl2水溶液 (500 nmol/mg ミトコンドリア蛋白質) を追加します。</li>
	<li>540 で吸光度の減少を記録 nm 毎の 3 10 分 (図 2) のためのソフトウェアによって制御されるマイクロ プレート リーダーの s。蛍光変化は、ミトコンドリアの内膜に溶質の流入によって引き起こされます。 注: 540 で吸光度の低下腫れミトコンドリアに対応する nm。読者は、吸光度の減少を観察しない長い間隔を読書や読書の時間が適用できます。</li>
</ol>

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X. 太陽監督実験です。魏の李は、実験を行った。陳張及び X 太陽を書いた紙。

ここでは、我々 はミトコンドリアの Ca2 +の保持の能力分析と Ca2 +のシンプルで効果的なプロトコルを記述した-ミトコンドリアの膨潤アッセイをトリガーされます。
ミトコンドリアの分離セルを均質化する場合は特にすべての材料およびチューブは氷の上が存在することを確認します。0.25% トリプシン-EDTA は、37 ° C で 5 分間料理から細胞を切り離す場合...

ミトコンドリアは、酸化的リン酸化による哺乳類細胞で使用される ATP の約 95% を生産する主要な細胞器官です。合成 ATP1に ADP をリン酸化して使用できます、ADP と無機リン酸の存在、人里離れたマイクロモル濃度 Ca2 +ミトコンドリアによって報告されます。細胞内 Ca2 +濃度がしきい値を超えると、ミトコンドリアが取り込み Ca2 +急速および流出それゆっくり。したがって、機能しているミトコンドリアは、増加した細胞内 Ca2 +の流入をことができます。無関係酸化的リン酸化に関与する、ミトコンドリア Ca2 +もゾル性細胞質カルシウム信号の部分を取るし、mPTP のミトコンドリアの内側の開口部を誘導することによってミトコンドリアを介したアポトーシスのメカニズムをアクティブにします。膜2。細胞内 Ca2 +の異常上昇が mPTP3を開くことによってミトコンドリアの大規模な腫れを引き起こすことができる広く認識されています。したがって、このプロトコルがミトコンドリアの Ca2 +保持能力と Ca2 +を定量化することでミトコンドリアの機能を評価することを目的-ミトコンドリアの膨潤が起きるというものです。
Ca2 +保持能力ゾル性細胞質カルシウムを摂取するミトコンドリアの機能の測定であります。ミトコンドリアは細胞内遊離カルシウムをバッファーし、使用頻度の低い沈殿物の形でカルシウム摂取によってカルシウム依存性細胞プロセスを調整できます。障害者 Ca2 +保持能力にエネルギー制限とも神経変性疾患4,5に関連するストレス現象に発生します。ミトコンまたはジギトニン グリセリン細胞 Ca2 +保持能力を識別するために使用できます、追加グルタミン酸とリンゴ酸分離ミトコンドリアによる Ca2 +を蓄積する高い能力は受けない、ミトコンドリアの分離手順6。ジギトニンの滴定された量を使用して、異なる種類の細胞の細胞膜を permeabilize ください。Hexapotassium 塩 Ca2 +-緑色蛍光染料、Ca2 +の結合-敏感な細胞非透過性可視光興奮インジケーターは、広く使用されている7をされています。Ca2 +-(5 分) 刺激8延長バインド緑蛍光染料は低親和性インジケーターで、無料の細胞内 Ca2 +濃度が上昇し続けることを示すために使用します。このメソッドは、放射性フィルター技術よりも敏感だったが、大幅に簡略化します。追加 Ca2 +カルシウム緑色蛍光を高め、ミトコンドリアの Ca2 +吸収がベースラインに蛍光を返します。逐次追加の Ca2 +は、ミトコンドリア吸収 extramitochondrial Ca2 + 9に失敗するまで行われました。蛍光マイクロ プレート リーダーは、継続的にカルシウム緑色蛍光を報告する使用できます。
Ca2 +蓄積の後、ミトコンドリアが脱分極し、中に Ca2 +放出ははれだした。Ca2 +-腫れ、mPTP 開口部を示すためミトコンドリアをトリガーします。電子顕微鏡、Ca2 +の測定に使用に 540 nm の吸光度の減少-ミトコンドリアの膨潤10,11をトリガーします。前方角度光散乱で12、吸光度の減少がミトコンドリアのマトリックスの受動的な腫れを反映ミトコンドリア ボリュームを直接的に確認することができます。
ここで、我々 はミトコンドリアの Ca2 +保持能力と Ca2 +を検討する方法論を説明-SH SY5Y 細胞から分離ミトコンドリア ミトコンドリアの膨潤をトリガーします。

<table><tbody><tr><td>SH-SY5Y cell line</td><td>ATCC (The Global Bioresource Center)</td><td>ATCC Number: CRL-2266</td><td></td></tr><tr><td>Calcium green-5N</td><td>Life Technologies</td><td>c-3737</td><td>Ca&lt;sup&gt;2+&lt;/sup&gt;-binding green fluorescent dye</td></tr><tr><td>complete protease inhibitors</td><td>Roche Molecular Biochemicals</td><td>4693116001</td><td></td></tr><tr><td>glass homogenizer</td><td>Kimble Chase</td><td>9885303002</td><td></td></tr><tr><td>glutamate</td><td>Sigma-Aldrich</td><td>RES5063G-A7</td><td></td></tr><tr><td>malate</td><td>Sigma-Aldrich</td><td>46940-U</td><td></td></tr><tr><td>rotenone</td><td>Sigma-Aldrich</td><td>R8875</td><td></td></tr><tr><td>HEPES</td><td>Sigma-Aldrich</td><td>H3375</td><td></td></tr><tr><td>MgCl&lt;sub&gt;2&lt;/sub&gt;</td><td>Sigma-Aldrich</td><td>00457</td><td></td></tr><tr><td>K&lt;sub&gt;2&lt;/sub&gt;HPO&lt;sub&gt;4&lt;/sub&gt;</td><td>Sigma-Aldrich</td><td>V900050</td><td></td></tr><tr><td>KCl</td><td>Sigma-Aldrich</td><td>P9541</td><td></td></tr><tr><td>CaCl&lt;sub&gt;2&lt;/sub&gt;</td><td>Sigma-Aldrich</td><td>V900266</td><td></td></tr><tr><td>Varioskan flash instruments</td><td>Thermo Scientific</td><td>IC100E</td><td></td></tr><tr><td>Bongkrekate</td><td>Biovision</td><td>1820-100</td><td></td></tr><tr><td>atractyloside</td><td>Sigma-Aldrich</td><td>C4992</td><td></td></tr><tr><td>high-glucose Dulbecco&amp;rsquo;s modified Eagle medium</td><td>Hyclone</td><td>SH30022</td><td>4.5 g/L glucose, L-glutamine, without sodium pyruvate</td></tr><tr><td>fetal bovine serum</td><td>Hyclone</td><td>SV30087</td><td></td></tr><tr><td>penicillin</td><td>Sigma-Aldrich</td><td>P3032</td><td></td></tr><tr><td>streptomycin</td><td>Invitrogen</td><td>11860-038</td><td></td></tr><tr><td>BCA assay kit</td><td>Thermo Scientific</td><td>NCI3225CH</td><td></td></tr><tr><td>PBS</td><td>Hyclone</td><td>SH30256.01</td><td></td></tr><tr><td>10 cm cell culture dish</td><td>NEST</td><td>704001</td><td></td></tr></tbody></table>

mitochondrial ca2+ retention capacity assay and ca2+-triggered mitochondrial swelling assay

酸化的リン酸化による ATP の生産は、ミトコンドリアの主要な機能です。高等真核生物のミトコンドリアは細胞内 Ca2 +のバッファリングにも参加し、ミトコンドリアで、ATP を生産することができます無料のミトコンドリア内 Ca2 +濃度によって媒介されます。Ca2 +保持能力は、ミトコンドリアのマトリックスでカルシウムを保持するミトコンドリアの機能としてみなすことができます。蓄積された細胞内 Ca2 +の内ミトコンドリア膜透過性につながるでは、ミトコンドリア膜透過性遷移孔 (mPTP)、分子と分子の漏れにつながる重量未満 1.5 kDa の開口部と呼ばれます。Ca2 +-腫れ、mPTP 開口部を示すためミトコンドリアをトリガーします。ここで、Ca2 +保持能力と Ca2 +を検討する 2 つの試金を記述-分離ミトコンドリア ミトコンドリアの膨潤をトリガーします。一定量に Ca2 +が追加されますすべての手順を実行することができます 1 日で完了なりマイクロ プレート リーダーによって記録されました。したがって、これら 2 つのシンプルで効果的なアッセイを採用して、Ca2 +を評価できる-関連するミトコンドリアの機能。

Ca2 +保持能力の代表の結果: 結果は、蛍光値として表現されました。Ca2 + (200 nmols/mg ミトコンドリア蛋白質)、mPTP 開口基準上増蛍光付加パルス。5 μ M Bongkrekate (BKA)、Ca2 +の阻害剤-mPTP が開いたり、1 μ M atractyloside (ATR)、Ca2 +の活性化を誘導-mPTP オープニングを誘発、ミトコン ドリアにしました。合計追加 Ca2 +ベースライ?...

Watch this Scientific Journal Video about Mitochondrial Ca2+ Retention Capacity Assay and Ca2+-triggered Mitochondrial Swelling Assay at JoVE.com

Mitochondrial Ca2+ Retention Capacity Assay and Ca2+-triggered Mitochondrial Swelling Assay

ミトコンドリアの Ca2 +保持容量測定と Ca2 +-ミトコンドリアの膨潤アッセイをトリガー

このプロトコルが Ca2 +保持能力と Ca2 +を調べる方法を説明することを目的 - トリガー SH SY5Y 分離ミトコンドリアの膨潤ミトコンドリア細胞ステップバイ ステップ。

The production of ATP by oxidative phosphorylation is the primary function of mitochondria. Mitochondria in higher eukaryotes also participate in ...

mitochondrial-ca2-retention-capacity-assay-ca2-triggered

Research

JoVE Journal

Neuroscience

Mitochondrial Ca2+ Retention Capacity Assay and Ca2+-triggered Mitochondrial Swelling Assay

11.1K ビュー.  Qilu Hospital of Shandong University. このプロトコルが Ca2 +保持能力と Ca2 +を調べる方法を説明することを目的 - トリガー SH SY5Y 分離ミトコンドリアの膨潤ミトコンドリア細胞ステップバイ ステップ。

ビデオ: Mitochondrial Ca2+ Retention Capacity Assay and Ca2+-triggered Mitochondrial Swelling Assay

Visualization of Mitochondrial DNA Replication in Individual Cells by EdU Signal Amplification

Mitochondria are key regulators of cellular energy and mitochondrial biogenesis is an essential component of regulating mitochondria numbers in healthy cells1-3. One approach for monitoring mitochondrial biogenesis is to measure the rate of mitochondrial DNA (mtDNA) replication4. We developed a sensitive technique to label newly synthesized mtDNA in individual cells in order to study mtDNA biogenesis. The technique combines the incorporation of 5-ethynyl-2'-deoxyuridine (EdU)5-7 with a tyramide signal amplification (TSA)8 protocol to visualize mtDNA replication within subcellular compartments of neurons. EdU is superior to other thymidine analogs, such as 5-bromo-2-deoxyuridine (BrdU), because the initial click reaction to label EdU5-7 does not require the harsh acid treatments or enzyme digests that are required for exposing the BrdU epitope. The milder labeling of EdU allows for direct comparison of its incorporation with other cellular markers9-10. The ability to visualize and quantify mtDNA biogenesis provides an essential tool for investigating the mechanisms used to regulate mitochondrial biogenesis and would provide insight into the pathogenesis associated with drug toxicity, aging, cancer and neurodegenerative diseases. Our technique is applicable to sensory neurons as well as other cell types. The use of this technique to measure mtDNA biogenesis has significant implications in furthering the understanding of both normal cellular physiology as well as impaired disease states.

We developed a sensitive technique to label newly synthesized mitochondrial DNA (mtDNA) in individual cells in order to study mtDNA biogenesis. The technique combines the incorporation of EdU together with a tyramide signal amplification (TSA) protocol to visualize mtDNA replication within subcellular compartments of neurons.

EDU信号増幅による個別細胞におけるミトコンドリアDNAの複製の可視化

Mitochondria are key regulators of cellular energy and mitochondrial biogenesis is an essential component of regulating mitochondria numbers in healthy ...

神経科学

Neuromodulation and Mitochondrial Transport: Live Imaging in Hippocampal Neurons over Long Durations

To understand the relationship between mitochondrial transport and neuronal function, it is critical to observe mitochondrial behavior in live cultured neurons for extended durations1-3. This is now possible through the use of vital dyes and fluorescent proteins with which cytoskeletal components, organelles, and other structures in living cells can be labeled and then visualized via dynamic fluorescence microscopy. For example, in embryonic chicken sympathetic neurons, mitochondrial movement was characterized using the vital dye rhodamine 1234. In another study, mitochondria were visualized in rat forebrain neurons by transfection of mitochondrially targeted eYFP5. However, imaging of primary neurons over minutes, hours, or even days presents a number of issues. Foremost among these are: 1) maintenance of culture conditions such as temperature, humidity, and pH during long imaging sessions; 2) a strong, stable fluorescent signal to assure both the quality of acquired images and accurate measurement of signal intensity during image analysis; and 3) limiting exposure times during image acquisition to minimize photobleaching and avoid phototoxicity.
Here, we describe a protocol that permits the observation, visualization, and analysis of mitochondrial movement in cultured hippocampal neurons with high temporal resolution and under optimal life support conditions. We have constructed an affordable stage-top incubator that provides good temperature regulation and atmospheric gas flow, and also limits the degree of media evaporation, assuring stable pH and osmolarity. This incubator is connected, via inlet and outlet hoses, to a standard tissue culture incubator, which provides constant humidity levels and an atmosphere of 5-10% CO2/air. This design offers a cost-effective alternative to significantly more expensive microscope incubators that don't necessarily assure the viability of cells over many hours or even days. To visualize mitochondria, we infect cells with a lentivirus encoding a red fluorescent protein that is targeted to the mitochondrion. This assures a strong and persistent signal, which, in conjunction with the use of a stable xenon light source, allows us to limit exposure times during image acquisition and all but precludes photobleaching and phototoxicity. Two injection ports on the top of the stage-top incubator allow the acute administration of neurotransmitters and other reagents intended to modulate mitochondrial movement. In sum, lentivirus-mediated expression of an organelle-targeted red fluorescent protein and the combination of our stage-top incubator, a conventional inverted fluorescence microscope, CCD camera, and xenon light source allow us to acquire time-lapse images of mitochondrial transport in living neurons over longer durations than those possible in studies deploying conventional vital dyes and off-the-shelf life support systems.

We describe a protocol that allows imaging of mitochondria in living neurons via fluorescence microscopy over long durations. Imaging over extended periods is accomplished through lentivirus-mediated expression of a mitochondrially targeted fluorescent protein and use of an inexpensive stage-top incubator that was designed and built in our laboratory.

ニューロモデュレーションとミトコンドリア輸送：長時間にわたって海馬ニューロンのライブイメージング

To understand the relationship between mitochondrial transport and neuronal function, it is critical to observe mitochondrial behavior in live cultured ...

Determination of Mitochondrial Membrane Potential and Reactive Oxygen Species in Live Rat Cortical Neurons

Mitochondrial membrane potential (&Delta;&Psi;m) is critical for maintaining the physiological function of the respiratory chain to generate ATP. A significant loss of &Delta;&Psi;m renders cells depleted of energy with subsequent death. Reactive oxygen species (ROS) are important signaling molecules, but their accumulation in pathological conditions leads to oxidative stress. The two major sources of ROS in cells are environmental toxins and the process of oxidative phosphorylation. Mitochondrial dysfunction and oxidative stress have been implicated in the pathophysiology of many diseases; therefore, the ability to determine &Delta;&Psi;m and ROS can provide important clues about the physiological status of the cell and the function of the mitochondria. 
Several fluorescent probes (Rhodamine 123, TMRM, TMRE, JC-1) can be used to determine &Delta;&psi;m in a variety of cell types, and many fluorescence indicators (Dihydroethidium, Dihydrorhodamine 123, H2DCF-DA) can be used to determine ROS. Nearly all of the available fluorescence probes used to assess &Delta;&Psi;m or ROS are single-wavelength indicators, which increase or decrease their fluorescence intensity proportional to a stimulus that increases or decreases the levels of &Delta;&Psi;m or ROS. Thus, it is imperative to measure the fluorescence intensity of these probes at the baseline level and after the application of a specific stimulus. This allows one to determine the percentage of change in fluorescence intensity between the baseline level and a stimulus. This change in fluorescence intensity reflects the change in relative levels of &Delta;&Psi;m or ROS. In this video, we demonstrate how to apply the fluorescence indicator, TMRM, in rat cortical neurons to determine the percentage change in TMRM fluorescence intensity between the baseline level and after applying FCCP, a mitochondrial uncoupler. The lower levels of TMRM fluorescence resulting from FCCP treatment reflect the depolarization of mitochondrial membrane potential. We also show how to apply the fluorescence probe H2DCF-DA to assess the level of ROS in cortical neurons, first at baseline and then after application of H2O2. This protocol (with minor modifications) can be also used to determine changes in &#x2206;&#x03A8;m and ROS in different cell types and in neurons isolated from other brain regions.

We demonstrate application of the fluorescence indicator, TMRM, in cortical neurons to determine the relative changes in TMRM fluorescence intensity before and after application of a specific stimulus. We also show application of the fluorescence probe H2DCF-DA to assess the relative level of reactive oxygen species in cortical neurons.

ライブラット皮質ニューロンのミトコンドリア膜電位と活性酸素種の定量

Mitochondrial membrane potential (&Delta;&Psi;m) is critical for maintaining the physiological function of the respiratory chain to generate ATP.  A ...

Analyses of Mitochondrial Calcium Influx in Isolated Mitochondria and Cultured Cells

Ca2+ handling by mitochondria is a critical function regulating both physiological and pathophysiological processes in a broad spectrum of cells. The ability to accurately measure the influx and efflux of Ca2+ from mitochondria is important for determining the role of mitochondrial Ca2+ handling in these processes. In this report, we present two methods for the measurement of mitochondrial Ca2+ handling in both isolated mitochondria and cultured cells. We first detail a plate reader-based platform for measuring mitochondrial Ca2+ uptake using the Ca2+ sensitive dye calcium green-5N. The plate reader-based format circumvents the need for specialized equipment, and the calcium green-5N dye is ideally suited for measuring Ca2+ from isolated tissue mitochondria. For our application, we describe the measurement of mitochondrial Ca2+ uptake in mitochondria isolated from mouse heart tissue; however, this procedure can be applied to measure mitochondrial Ca2+ uptake in mitochondria isolated from other tissues such as liver, skeletal muscle, and brain. Secondly, we describe a confocal microscopy-based assay for measurement of mitochondrial Ca2+ in permeabilized cells using the Ca2+ sensitive dye Rhod-2/AM and imaging using 2-dimensional laser-scanning microscopy. This permeabilization protocol eliminates cytosolic dye contamination, allowing for specific recording of changes in mitochondrial Ca2+. Moreover, laser-scanning microscopy allows for high frame rates to capture rapid changes in mitochondrial Ca2+ in response to various drugs or reagents applied in the external solution. This protocol can be applied to measure mitochondrial Ca2+ uptake in many cell types including primary cells such as cardiac myocytes and neurons, and immortalized cell lines.

Here, we present two protocols for the measurement of mitochondrial Ca2+ influx in isolated mitochondria and cultured cells. For isolated mitochondria, we detail a plate reader-based Ca2+ import assay using the Ca2+ sensitive dye calcium green-5N. For cultured cells, we describe a confocal microscopy method using the Ca2+ dye Rhod-2/AM.

ミトコンドリアの分離と培養細胞におけるミトコンドリアのカルシウム流入の解析

Ca2+ handling by mitochondria is a critical function regulating both physiological and pathophysiological processes in a broad spectrum of cells. The ...

生化学

Monitoring Dynamic Changes In Mitochondrial Calcium Levels During Apoptosis Using A Genetically Encoded Calcium Sensor

Dynamic changes in intracellular calcium concentration in response to various stimuli regulates many cellular processes such as proliferation, differentiation, and apoptosis1. During apoptosis, calcium accumulation in mitochondria promotes the release of pro-apoptotic factors from the mitochondria into the cytosol2. It is therefore of interest to directly measure mitochondrial calcium in living cells in situ during apoptosis. High-resolution fluorescent imaging of cells loaded with dual-excitation ratiometric and non-ratiometric synthetic calcium indicator dyes has been proven to be a reliable and versatile tool to study various aspects of intracellular calcium signaling. Measuring cytosolic calcium fluxes using these techniques is relatively straightforward. However, measuring intramitochondrial calcium levels in intact cells using synthetic calcium indicators such as rhod-2 and rhod-FF is more challenging. Synthetic indicators targeted to mitochondria have blunted responses to repetitive increases in mitochondrial calcium, and disrupt mitochondrial morphology3. Additionally, synthetic indicators tend to leak out of mitochondria over several hours which makes them unsuitable for long-term experiments. Thus, genetically encoded calcium indicators based upon green fluorescent protein (GFP)4 or aequorin5 targeted to mitochondria have greatly facilitated measurement of mitochondrial calcium dynamics. Here, we describe a simple method for real-time measurement of mitochondrial calcium fluxes in response to different stimuli. The method is based on fluorescence microscopy of 'ratiometric-pericam' which is selectively targeted to mitochondria. Ratiometric pericam is a calcium indicator based on a fusion of circularly permuted yellow fluorescent protein and calmodulin4. Binding of calcium to ratiometric pericam causes a shift of its excitation peak from 415 nm to 494 nm, while the emission spectrum, which peaks around 515 nm, remains unchanged. Ratiometric pericam binds a single calcium ion with a dissociation constant in vitro of ~1.7 &mu;M4. These properties of ratiometric pericam allow the quantification of rapid and long-term changes in mitochondrial calcium concentration. Furthermore, we describe adaptation of this methodology to a standard wide-field calcium imaging microscope with commonly available filter sets. Using two distinct agonists, the purinergic agonist ATP and apoptosis-inducing drug staurosporine, we demonstrate that this method is appropriate for monitoring changes in mitochondrial calcium concentration with a temporal resolution of seconds to hours. Furthermore, we also demonstrate that ratiometric pericam is also useful for measuring mitochondrial fission/fragmentation during apoptosis. Thus, ratiometric pericam is particularly well suited for continuous long-term measurement of mitochondrial calcium dynamics during apoptosis.

This protocol describes a method for real-time measurement of mitochondrial calcium fluxes by fluorescent imaging. The method takes advantage of a circularly permutated YFP-based dual-excitation ratiometric calcium sensor (ratiometric pericam-mt) selectively expressed in mitochondria.

遺伝的にコードされたカルシウムのセンサを用いたアポトーシス時のミトコンドリア内カルシウム濃度の動的変更の監視

Dynamic changes in intracellular calcium concentration in response to various stimuli regulates many cellular processes such as proliferation, ...

生物学

Multi-parameter Measurement of the Permeability Transition Pore Opening in Isolated Mouse Heart Mitochondria

The mitochondrial permeability transition pore (mtPTP) is a non specific channel that forms in the inner mitochondrial membrane to transport solutes with a molecular mass smaller than 1.5 kDa. Although the definitive molecular identity of the pore is still under debate, proteins such as cyclophilin D, VDAC and ANT contribute to mtPTP formation. While the involvement of mtPTP opening in cell death is well established1, accumulating evidence indicates that the mtPTP serves a physiologic role during mitochondrial Ca2+ homeostasis2, bioenergetics and redox signaling 3.
mtPTP opening is triggered by matrix Ca2+ but its activity can be modulated by several other factors such as oxidative stress, adenine nucleotide depletion, high concentrations of Pi, mitochondrial membrane depolarization or uncoupling, and long chain fatty acids4. In vitro, mtPTP opening can be achieved by increasing Ca2+ concentration inside the mitochondrial matrix through exogenous additions of Ca2+ (calcium retention capacity). When Ca2+ levels inside mitochondria reach a certain threshold, the mtPTP opens and facilitates Ca2+ release, dissipation of the proton motive force, membrane potential collapse and an increase in mitochondrial matrix volume (swelling) that ultimately leads to the rupture of the outer mitochondrial membrane and irreversible loss of organelle function.
Here we describe a fluorometric assay that allows for a comprehensive characterization of mtPTP opening in isolated mouse heart mitochondria. The assay involves the simultaneous measurement of 3 mitochondrial parameters that are altered when mtPTP opening occurs: mitochondrial Ca2+ handling (uptake and release, as measured by Ca2+ concentration in the assay medium), mitochondrial membrane potential, and mitochondrial volume. The dyes employed for Ca2+ measurement in the assay medium and mitochondrial membrane potential are Fura FF, a membrane impermeant, ratiometric indicator which undergoes a shift in the excitation wavelength in the presence of Ca2+, and JC-1, a cationic, ratiometric indicator which forms green monomers or red aggregates at low and high membrane potential, respectively. Changes in mitochondrial volume are measured by recording light scattering by the mitochondrial suspension. Since high-quality, functional mitochondria are required for the mtPTP opening assay, we also describe the steps necessary to obtain intact, highly coupled and functional isolated heart mitochondria.

A spectrofluorometric protocol for the measurement of the mitochondrial permeability transition pore opening in isolated mouse heart mitochondria is presented here. The assay involves the simultaneous measurement of mitochondria Ca2+ handling, mitochondrial membrane potential and mitochondrial volume. The procedure for obtaining high-quality and functional heart mitochondria is also described.

単離ミトコンドリアマウス心臓における透水性遷移孔の開口部のマルチパラメータ測定

The mitochondrial permeability transition pore (mtPTP) is a non specific channel that forms in the inner mitochondrial membrane to transport solutes with ...

Simultaneous Measurement of Mitochondrial Calcium and Mitochondrial Membrane Potential in Live Cells by Fluorescent Microscopy

Apart from their essential role in generating ATP, mitochondria also act as local calcium (Ca2+) buffers to tightly regulate intracellular Ca2+ concentration. To do this, mitochondria utilize the electrochemical potential across their inner membrane (&#916;&#936;m) to sequester Ca2+. The influx of Ca2+ into the mitochondria stimulates three rate-limiting dehydrogenases of the citric acid cycle, increasing electron transfer through the oxidative phosphorylation (OXPHOS) complexes. This stimulation maintains &#916;&#936;m, which is temporarily dissipated as the positive calcium ions cross the mitochondrial inner membrane into the mitochondrial matrix.
We describe here a method for simultaneously measuring mitochondria Ca2+ uptake and &#916;&#936;m in live cells using confocal microscopy. By permeabilizing the cells, mitochondrial Ca2+ can be measured using the fluorescent Ca2+ indicator Fluo-4, AM, with measurement of &#916;&#936;m using the fluorescent dye tetramethylrhodamine, methyl ester, perchlorate (TMRM). The benefit of this system is that there is very little spectral overlap between the fluorescent dyes, allowing accurate measurement of mitochondrial Ca2+ and &#916;&#936;m simultaneously. Using the sequential addition of Ca2+ aliquots, mitochondrial Ca2+ uptake can be monitored, and the concentration at which Ca2+ induces mitochondrial membrane permeability transition and the loss of &#916;&#936;m determined.

Mitochondria can utilize the electrochemical potential across their inner membrane (&#916;&#936;m) to sequester calcium (Ca2+), allowing them to shape cytosolic Ca2+ signaling within the cell. We describe a method for simultaneously measuring mitochondria Ca2+ uptake and &#916;&#936;m in live cells using fluorescent dyes and confocal microscopy.

蛍光顕微鏡による生細胞内のミトコンドリアのカルシウムとミトコンドリア膜電位の同時測定

Apart from their essential role in generating ATP, mitochondria also act as local calcium (Ca2+) buffers to tightly regulate intracellular Ca2+ ...

Calcium Influx Assay to Measure Mitochondrial Calcium Uptake in Cultured Cells

Source: Maxwell, J.T., et al., <a href="https://app.jove.com/v/57225">Analyses of Mitochondrial Calcium Influx in Isolated Mitochondria and Cultured Cells.</a> J. Vis. Exp. (2018).
This video describes a confocal microscopy imaging-based assay to measure mitochondrial calcium uptake in cultured cells. The assay uses the calcium-sensitive fluorescent dye Rhod-2/AM to measure the mitochondrial calcium in permeabilized cultured cells.

培養細胞におけるミトコンドリアカルシウム取り込みを測定するためのカルシウム注入アッセイ

Source: Maxwell, J.T., et al., Analyses of Mitochondrial Calcium Influx in Isolated Mitochondria and Cultured Cells. J. Vis. Exp. (2018).
This video ...

JoVE Encyclopedia of Experiments

生物学的手法

アッセイ技術

細胞ベースのアッセイ

Mitochondrial Calcium Uptake Assay: A Plate Reader-Based Method for Measuring Calcium Uptake in Isolated Mitochondria

Source: Maxwell, J.T., et al., <a href="https://app.jove.com/v/57225">Analyses of Mitochondrial Calcium Influx in Isolated Mitochondria and Cultured Cells.</a> J. Vis. Exp. (2018).
This video describes a plate reader-based assay to measure mitochondrial calcium uptake in isolated mitochondria. The assay analyzes the fluorescence signal of a calcium-sensitive fluorescent dye to study the kinetics of mitochondrial calcium uptake and calcium overload.

ミトコンドリアカルシウム取り込みアッセイ:単離されたミトコンドリアにおけるカルシウム取り込みを測定するためのプレートリーダーベースの方法

生化学的アッセイ

Determination of the Calcium Retention Capacity of Isolated Mitochondria

Source: Li, W., et. al. <a href="https://app.jove.com/v/56236">Mitochondrial Ca2+ Retention Capacity Assay and Ca2+-triggered Mitochondrial Swelling Assay.</a> J. Vis. Exp. (2018)
This video demonstrates the procedure to assess mitochondrial calcium retention capacity by monitoring real-time changes in fluorescence as mitochondria uptake calcium. This assay is useful for studying mitochondrial function and calcium-related processes, including apoptosis and neurodegenerative diseases.

Source: Li, W., et. al. Mitochondrial Ca2+ Retention Capacity Assay and Ca2+-triggered Mitochondrial Swelling Assay. J. Vis. Exp. (2018)
This video ...

ミトコンドリアの Ca^{2 +}保持容量測定と Ca^{2 +}-ミトコンドリアの膨潤アッセイをトリガー

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