この作品は、日本の財団法人上原記念生命科学財団（ESの）だけでなく、ホワイトホール財団、神経疾患や脳卒中の国立研究所とスタインハイマー基金賞（BSKまで）によってサポートされていました。

実験手順実験手順は以下のステップ賢明な方法で説明されている2つのキーの部分で構成されています。 パート1：はPREPARING海馬アストロサイトの培養簡単に言えば、混合海馬アストロサイトニューロン培養物を、十分に確立されたプロトコル1,2,3を用いて調製した。我々は、健全な培養アストロサイトを生成する手順を最適化。以下に記載されているすべての手順は、このような層流フードのような無菌環境で実施されるべきである。 準備カバースリップ <ul><li> 22 mmのカバースリップ（VWR、48380〜068） </li><li>ポリ- D -リシン（PDL、シグマP0899）、アリコート（1 mg / ml）を</li><li>ラミニンアリコート（20μg/ ml）を1 mg / mlのラミニン溶液（シグマL2020）に滅菌水49 mlを追加し、-20℃、1.2 mlのアリコートとストアを行う</li></ul><ol><li> （50μg/ ml）を滅菌​​水でPDLを溶かす</li><li>カバーグラスをオートクレーブ、PDLの滅菌水と場所（100カバースリップ用20 ml）ですすいでください。室温で一晩おきます。 </li><li>滅菌水（3広範な洗浄）とPDLを交換してください。その後、4でカバーガラスと店舗℃を乾燥させる</li><li>アストロサイトをメッキ前日、場所6ウェルプレート（バイオサイエンスBDから滅菌蓋、とウェルフラットボトムプレート）上で無菌ウェル中の個々のカバースリップ。各カバースリップ上ラミニンの400μlを入れ、蒸発を避けるために、インキュベーターで、一晩インキュベートする。 </li></ol> 解剖 解剖のメディア： <ul><li> 500ミリリットルアールの平衡塩類溶液（EBSS）（1X）、液体（Invitrogen社、14155〜063） </li><li> 5ミリリットルHEPES溶液（Sigma、H0887） </li></ul> 海馬メディア： <ul><li> 412.5ミリリットル最小必須培地（MEM）（1X）、液体はアールの塩類が含まれていますが、ないL -グルタミンまたはフェノールレッド（Invitrogen社、51200〜038） </li><li> 10 mlのグルコース（Sigma社、D -（+） - グルコース無水物SIGMA ULTRA G7528）MEMで1 M </li><li> 5ミリリットルペニシリン - ストレプトマイシン（Invitrogen社、15140〜122） </li><li> 5 mlのピ​​ルビン酸ナトリウム溶液（Sigma社、S8636） </li><li> 12.5ミリリットルHEPES溶液1 M（シグマ、H0887） </li><li> 5ミリリットルN - 2サプリメント（100X）、液体（Invitrogen社、17502〜048） </li><li> 50ミリリットルウマ血清、熱不活化（Invitrogen社、26050〜088） </li></ul> パパインのソリューション： <ul><li>ワーシントンパパイン- 022バイアル（LK003178、最終濃度が20 U / ml）に解剖メディアの5 mlを加え37℃で60分間℃でインキュベートする。 </li></ul><ol><li> P1（通常は2匹）の国内規制及び最寄りの動物実験使用の委員会で吟味し、承認されたガイドラインに従って、老化ラットの仔を刎ねる。 </li><li>コー​​ルド解剖メディアで満たされたペトリ皿で​​皮膚と頭蓋骨と場所の脳を取り外します。 </li><li>髄膜を除去、両半球を細かく分析し、海馬を解剖。 </li><li> 37パパイン溶液中で〜1X1 mmの片とダイジェスト℃で11〜13分間に海馬を切る。 </li><li>組織片が定着したら、慎重にパパイン酵素の痕跡をすべて削除するには、海馬培地5mlを追加削除します。海馬培地（2ml）中のこのステップを再懸濁しますを繰り返します。 </li><li>徐々に小さく穴（1000μmの、〜500μmおよび〜300μm以下）の三火炎研磨ピペットで残って塊が、なくなるまで細胞〜5回をひいて粉にする。 </li><li>一度粉砕し、セルストレーナー（孔径、70ミクロン、BDバイオサイエンス社）を介して細胞を通過する。懸濁液10μlに細胞を数える。 40万細胞/ mlを持つために、海馬のメディアの音量を調整します。 </li><li>カバースリップオフラミニンを吸引し、カバースリップあたりの細胞懸濁液のカバーが乾燥する前に、プレートを200μl。 </li><li>インキュベーター内で60分間添付し、ウェルあたり海馬培地2mlを追加するためにそれらを残す。 </li><li>翌日、死んだ細胞や破片を除去し、予め温めておいた新鮮な海馬培地2mlを追加するには、古い海馬の培地を吸引除去する。 </li></ol> メンテナンス Neurobasalメディア： <ul><li> 500ミリリットルneurobasal（Invitrogen社、12348〜017） </li><li> 10ミリリットルB27の無血清サプリメント（Invitrogen社、17504〜044） </li><li> 5ミリリットルペニシリン - ストレプトマイシン（Invitrogen社、15140〜122） </li><li> 1.25ミリリットル、L -グルタミン（Invitrogen社、25030〜149） </li></ul>メッキ後4日から始まる、neurobasal培地でアストロサイトニューロンの培養週に2回通します。温度とCO 2を平衡化するために換気フラスコ内のインキュベーターで30分程度のメディアをPreincubate。 パート2：カルシウムイメージング海馬レコーディングバッファ：110 mMのNaCl、5.4 mMののKCl、1.8 mMのCaCl 2を 、0.8 mMのMgCl 2、10mMのD -グルコース、10mMのHEPES（シグマからすべての化学物質）を用いてpH 7.4（NaOHで調整）。 アストロサイトへのカルシウム指示薬のロード <ol><li> （Invitrogen社、DMSOは2.5μMであるFluo - 4、AM（Invitrogen社、F - 14217）と、0.05％プルロニック® F - 127 20％溶液の入った2ミリリットル海馬記録バッファーを充填した6ウェルプレートにウェルに文化を置きますP - 3000MP）と,10 - 30分間室温でインキュベートする。 </li><li>であるFluo - 4ソリューションを削除し、30分間室温で海馬の記録バッファとインキュベートしてカバーグラスを3回洗浄。 </li><li>チャンバーにカバースリップを置き、レンズクリーニング液でカバースリップの反対側を清掃してください。 </li><li>客観的に液浸オイルの一つの小さな滴（Cargilleから液浸オイルタイプのDFを）入れて、顕微鏡のステージ（オリンパスIX71）にチャンバー（ワーナー音源から25 mmの円形のカバーのオープンチャンバー）を置く。 </li><li>細胞がどのように見えるかを確認し、フォーカスにそれらを得るために透過光を用いて細胞を調べます。その後モノクロから488 nmの（ビジョンTILLからポリクロームV）で細胞を照らすとみたFluo - 4の蛍光シグナルがアストロサイトで均​​一と検出可能であるかどうかを判断する。 </li><li>アストロサイトのカルシウムを測定するために、EPIと全反射照明を使用してください。 </li></ol> 全反射顕微鏡 簡単に言えば、我々は、アンドールIXON DV887DCS EMCCDカメラを搭載したオリンパスIX71顕微鏡を使用してください。励起と画像取得の制御は、TILLVisionのソフトウェアを使用して実現されます。 454/488/515 nmのアルゴン（100 mWの）および442 nmの固体状態（45 MW）レーザのビームを組み合わせて使用​​して制御されるまで、ポリラインレーザーコンバイナ、TIRFデュアルポートのコンデンサーとacoustopticalチューナブルフィルタとコントローラ（AOTF;すべてからフォトニクスTILL）と全反射のコンデンサーに入るためKineflex広帯域光ファイバに供給。我々は、全反射を達成するためにオリンパス60X 1.45 NAのレンズを使用。カメラのゲインは、ノイズ画像に最適な信号を提供するために、それぞれの星状膠細胞に調整されます。背景と全反射顕微鏡の原理は、最近、5日している。我々が使用する光学部品のほとんどは、今アジレントテクノロジー（http://www.till-photonics.com/）の一部であるフォトニクス、TILLから購入した。 TIRの侵入深さは次式から計算することができます。 <img style="float:left;" src="/files/ftp_upload/1142/equation.png" alt="式" /> D =侵入深さガラスのN1 =屈折率セルのN2 =屈折率発生率の=角発生率のNAI =開口数 レーザーは全反射のために最適に整列されていることを確認するために我々は100nmの蛍光ビーズ（Invitrogen社、F8803）を観察すると便利です。我々は、EPIと全反射顕微鏡でビーズの静止フレームとビデオを提示する。ときに全反射で、一つは信号対雑音の劇的な増加を観察し、ビーズはブラウン拡散が表示されます。我々は最適な全反射ではなく、臨界角に等しいではなかった場合に発生する危険にさらさ斜入射照明ではなく、発生したことを確認するために、定期的に全反射顕微鏡と100 nmのビーズ（〜週1回）の挙動を観察すると便利ですα（図1参照）。 G蛋白質共役型受容体アゴニストのアプリケーション アストロサイトは、代謝型グルタミン酸受容体とP2Y受容体（アゴニスト、ATP、ADP）を含むGQ -共役受容体6,7の様々な表現。これらの受容体の活性化は、星状膠細胞内細胞内カルシウムレベルの大幅な増加につながる。例えば、人は容易にアストロ8-10にATP（30μM）の適用時に細胞内カルシウムの上昇を観察することができます。我々はワーナー音源からのスイッチャーは、VC - 77SPファーストステップ灌流システム（http://www.warneronline.com/index.cfm）と呼ばれる高速なソリューションを使用してください。この方法では解決策は以下〜10ミリ秒未満に適用することができます。 <img src="/files/ftp_upload/1142/Fig 1a.jpg" alt="図1" /> <img src="/files/ftp_upload/1142/fig1c.jpg" alt="" /> 図1漫画やイメージングの写真は、設定する。 （B）レーザーアセンブリ、コントローラとビームボックスの写真を示すのに対し、A.は、airtableにマウントされている顕微鏡の写真を表示します。 C.は、イメージングのためにマウントされているチャンバーと顕微鏡のステージの写真を表示します。左の高速灌流装置（ステッピングモーターとシータのチューブと一緒に）見ることができます。右上Axopatch 200Aアンプのヘッドステージが見られる。漫画はセット内の光パスをschematizesとどのようにTIRFが達成されます。レーザーは、60X 1.45 NAの対物レンズの後焦点面に焦点を当てて、それが臨界角をαでイマージョンオイルに出てくるようにその位置がセンターをオフに調整されます。この時点で、ビームは、より低い屈折率の媒質中に距離λ（メインテキストの式を参照）で内部全反射と減衰に苦しんでいる。この場合、これはアストロサイトとアストロサイト自身を取り巻く録音バッファです。結果は、形質膜の〜100nmの内の分子の光学的励起（したがって画像）です。細胞内や細胞の上部表面上のものが励起されていないのに対し、細胞の漫画では、これは、緑色の&quot;興奮&quot;膜受容体として示されています。全反射顕微鏡の完全なアカウントはSteyerとAlmers 4で提供されています。 <img src="/files/ftp_upload/1142/fig2.png" alt="図2" /> 図2。EPIと全反射顕微鏡で取得した100nmの蛍光ビーズの画像。 A.は、数十100nmの蛍光ビーズと視野のEPI画像を表示します。青い矢印は水の拡散であるビーズを指すのに対し、ガラスのカバースリップの上に定住しているビーズに赤い矢印のポイント。このビューではAに示すようにB.は赤い矢印で示される接着ビーズが表示されるビューの同じフィールドの全反射画像を表示します。これらはガラスのcoverlsipに定住し、〜100nmのエバネッセント場内でこのようにしたしていたためです。青色の矢印でに示されているビーズは、この領域内にないため、全反射の画像では見えません。下のプロットは、画像の3Dレンダリングを示しています。それは、全反射顕微鏡で観察すると、信号対ノイズの大幅な増加は、エバネッセント場内のビーズのために起こることは明らかである。全反射のためにそれが20であったのに対し± 0.7実際にはこれらのイメージのためにEPIのための信号対雑音比は、7.1 ± 0.6であった。 <img src="/files/ftp_upload/1142/fig3.png" alt="図3" /> 図3。EPIと全反射顕微鏡で取得したフルオ-4カルシウム指示薬を搭載したアストロサイトの画像。 fiveアストロサイトとビューのフィールドのA. EPI画像。 AとBのイメージが大きく異なることをBに示すように、B.ビューの同じフィールドの全反射像は注意してください。 TIRF照明とガラスのカバースリップに近い同格でのみ細胞膜領域がイメージングされているためです。下のパネルでは、EPIと全反射顕微鏡で撮像ATP誘発細胞内カルシウムトランジェントを示しています。

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それは、アストロサイトは細胞内カルシウムの上昇を表示することが十分に確立されている。これらは自発的に発生する、アストロサイト表面11上の受容体を活性化するニューロンの活動によって、またはアゴニストのアプリケーションによってトリガーすることができます。一つの重要なと論争はアストロサイト細胞内カルシウムの上昇が神経細胞11、12に受容体を活性化するシグナル伝達...

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		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
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<tr>
<td>VWR&#174; Micro Cover Slips, Round, No. 1</td>
<td>Tool</td>
<td>VWR</td>
<td>48380-068</td>
<td>&nbsp;</td>
<tr>
<td>Poly-D-lysine hydrobromide</td>
<td>Reagent</td>
<td>Sigma</td>
<td>P0899</td>
<td>&nbsp;</td>
<tr>
<td>Laminin from Engelbreth-Holm-Swarm murine sarcoma basement membrane</td>
<td>Reagent</td>
<td>Sigma</td>
<td>L2020</td>
<td>&nbsp;</td>
<tr>
<td>Earle&#x2019;s Balanced Salt Solution (EBSS) (1X), liquid</td>
<td>Reagent</td>
<td>Invitrogen</td>
<td>14155-063</td>
<td>&nbsp;</td>
<tr>
<td>Minimum Essential Medium (MEM) (1X), liquid Contains Earle's salts, but no L-glutamine or phenol red</td>
<td>Reagent</td>
<td>Invitrogen</td>
<td>51200-038</td>
<td>&nbsp;</td>
<tr>
<td>Penicillin-Streptomycin liquid</td>
<td>Reagent</td>
<td>Invitrogen</td>
<td>15140-122</td>
<td>&nbsp;</td>
<tr>
<td>Sodium pyruvate solution</td>
<td>Reagent</td>
<td>Sigma</td>
<td>S8636</td>
<td>&nbsp;</td>
<tr>
<td>HEPES solution 1 M</td>
<td>Reagent</td>
<td>Sigma</td>
<td>H0887</td>
<td>&nbsp;</td>
<tr>
<td>N-2 Supplement (100X), liquid</td>
<td>Reagent</td>
<td>Invitrogen</td>
<td>17502-048</td>
<td>&nbsp;</td>
<tr>
<td>Horse Serum, Heat-Inactivated</td>
<td>Reagent</td>
<td>Invitrogen</td>
<td>26050-088</td>
<td>&nbsp;</td>
<tr>
<td>PAPAIN-022</td>
<td>Reagent</td>
<td>Worthington</td>
<td>LK003178</td>
<td>&nbsp;</td>
<tr>
<td>Neurobasal&#x2122; Medium (1X) Liquid without Phenol Red</td>
<td>Reagent</td>
<td>Invitrogen</td>
<td>12348-017</td>
<td>&nbsp;</td>
<tr>
<td>B-27 Serum-Free Supplement (50X), liquid</td>
<td>Reagent</td>
<td>Invitrogen</td>
<td>17504-044</td>
<td>&nbsp;</td>
<tr>
<td>L-Glutamine-200 mM (100X), liquid</td>
<td>Reagent</td>
<td>Invitrogen</td>
<td>25030-149</td>
<td>&nbsp;</td>
<tr>
<td>Cell Strainers</td>
<td>Tool</td>
<td>BD Biosciences</td>
<td>352350</td>
<td>&nbsp;</td>
<tr>
<td>BD Falcon Multiwell Flat-Bottom Plates with Lids, Sterile</td>
<td>Tool</td>
<td>BD Biosciences</td>
<td>353046</td>
<td>&nbsp;</td>
<tr>
<td>NaCl</td>
<td>Reagent</td>
<td>Sigma</td>
<td>S7653</td>
<td>&nbsp;</td>
<tr>
<td>KCl</td>
<td>Reagent</td>
<td>Sigma</td>
<td>P3911</td>
<td>&nbsp;</td>
<tr>
<td>CaCl2 hexahydrate</td>
<td>Reagent</td>
<td>Sigma</td>
<td>21108</td>
<td>&nbsp;</td>
<tr>
<td>MgCl2 hexahydrate</td>
<td>Reagent</td>
<td>Sigma</td>
<td>M2670</td>
<td>&nbsp;</td>
<tr>
<td>HEPES free acid</td>
<td>Reagent</td>
<td>Sigma</td>
<td>H3375</td>
<td>&nbsp;</td>
<tr>
<td>D-(+)-glucose</td>
<td>Reagent</td>
<td>Sigma</td>
<td>G7528</td>
<td>&nbsp;</td>
<tr>
<td>Fluo-4, AM 1 mM solution in DMSO</td>
<td>Reagent</td>
<td>Invitrogen</td>
<td>F-14217</td>
<td>&nbsp;</td>
<tr>
<td>Pluronic&#174; F-127 20% solution in DMSO</td>
<td>Reagent</td>
<td>Invitrogen</td>
<td>P-3000MP</td>
<td>&nbsp;</td>
<tr>
<td>Immersion Oil TYPE DF</td>
<td>Microscope</td>
<td>Cargille</td>
<td>16242</td>
<td>&nbsp;</td>
<tr>
<td>Open chamber for 25 mm round coverslips, 100 &mu;l volume</td>
<td>Tool</td>
<td>WARNER Instruments</td>
<td>64-0362 (RC-21BDW)</td>
<td>&nbsp;</td>
<tr>
<td>P-2 platform for Series 20 chambers, non-heater</td>
<td>Tool</td>
<td>WARNER Instruments</td>
<td>64-0278 (P-2)</td>
<td>&nbsp;</td>
<tr>
<td>FluoSpheres carboxylate-modified microspheres, 0.1 &mu;m, yellow-green fluorescent (505/515) 2% solids</td>
<td>Reagent</td>
<td>Invitrogen</td>
<td>F8803</td>
<td>&nbsp;</td>		</tbody>
		</table>
		</div>

measuring near plasma membrane and global intracellular calcium dynamics in astrocytes

脳は、グリア細胞が含まれています。アストロサイト、グリア細胞の種類は、神経細胞に受動的な支援する役割を提供するために長い間知られている。しかし、増加する証拠は、アストロサイトはまた、積極的に神経細胞との機能的な相互作用を介して脳機能に関与する可能性を示唆している。しかし、アストロサイト生物学の多くの基本的な側面は、議論の不明確及び/または実験的に未踏のまま。重要な問題の1つは、アストロサイトにおける細胞内カルシウムトランジェントのダイナミクスである。カルシウムが十分に重要なセカンドメッセンジャーとして確立されているため、それがアストロサイトのカルシウムの上昇は、アストロサイトからの伝達物質の遊離を引き起こすことができることが提案されているので、これは関連しています。しかし、アストロサイトのシグナル伝達の近くに、細胞膜のカルシウムの任意の詳細や満足な説明がされていません。全内部反射蛍光（全反射）顕微鏡は、生きた細胞の原形質膜の約100nm内で生理学的に関連するシグナル伝達事象を分析するための強力なツールです。ここでは、全反射顕微鏡を使用し、ほぼ同時に形質膜とグローバルな細胞内カルシウム動態の近くに監視する方法について説明します。このアプローチのさらなる改良と体系的なアプリケーションは、アストロサイトのカルシウムシグナル伝達の正確な詳細をお知らせする可能性があります。アストロサイトのカルシウム動態の詳細な理解は、次の場合に、どのように、いつ、なぜアストロサイトとニューロンはカルシウム依存性の機能的相互作用を受ける理解する基礎を提供することがあります。

Watch this Scientific Journal Video about Measuring Near Plasma Membrane and Global Intracellular Calcium Dynamics in Astrocytes at JoVE.com

Measuring Near Plasma Membrane and Global Intracellular Calcium Dynamics in Astrocytes

我々は内部全反射し、落射蛍光顕微鏡を用いて培養アストロサイトにおける膜とグローバルな細胞内カルシウム動態の近くで測定する方法について説明します。

アストロサイトの細胞膜とグローバル細胞内カルシウム動態の近くの測定

The brain contains glial cells.  Astrocytes, a type of glial cell, have long been known to provide a passive supportive role to neurons. However, ...

measuring-near-plasma-membrane-global-intracellular-calcium-dynamics

Research

JoVE Journal

Biology

13.0K ビュー.  David Geffen School of Medicine, University of California, Los Angeles. 我々は内部全反射し、落射蛍光顕微鏡を用いて培養アストロサイトにおける膜とグローバルな細胞内カルシウム動態の近くで測定する方法について説明します。

ビデオ: Measuring Near Plasma Membrane and Global Intracellular Calcium Dynamics in Astrocytes

Measuring Plasma Membrane Protein Endocytic Rates by Reversible Biotinylation

Plasma membrane proteins are a large, diverse group of proteins comprised of receptors, ion channels, transporters and pumps.  Activity of these proteins is responsible for a variety of key cellular events, including nutrient delivery, cellular excitability, and chemical signaling.  Many plasma membrane proteins are dynamically regulated by endocytic trafficking, which modulates protein function by altering protein surface expression.  The mechanisms that facilitate protein endocytosis are complex and are not fully understood for many membrane proteins.  In order to fully understand the mechanisms that control the endocytic trafficking of a given protein, it is critical that the protein s endocytic rate be precisely measured.  For many receptors, direct endocytic rate measurements are frequently achieved utilizing labeled receptor ligands.  However, for many classes of membrane proteins, such as transporters, pumps and ion channels, there is no convenient ligand that can be used to measure the endocytic rate.  In the present report, we describe a reversible biotinylation method that we employ to measure the dopamine transporter (DAT) endocytic rate.  This method provides a straightforward approach to measuring internalization rates, and can be easily employed for trafficking studies of most membrane proteins.

Regulated endocytosis governs the cell surface expression levels of the majority of membrane proteins. Here we utilize reducible, membrane impermeant biotinylation reagents to measure the endocytic rate of the dopamine transporter (DAT), a polytopic membrane protein. The method facilitates a straightforward approach to measuring the endocytic rate of most plasma membrane proteins.

リバーシブルビオチン化によって原形質膜タンパク質エンドサイトーシス率を測定

Plasma membrane proteins are a large, diverse group of proteins comprised of receptors, ion channels, transporters and pumps.  Activity of these proteins ...

生物学

Measuring Fast Calcium Fluxes in Cardiomyocytes

Cardiomyocytes have multiple Ca2+ fluxes of varying duration that work together to optimize function 1,2. Changes in Ca2+ activity in response to extracellular agents is predominantly regulated by the phospholipase C&beta;- G&alpha;q pathway localized on the plasma membrane which is stimulated by agents such as acetylcholine 3,4. We have recently found that plasma membrane protein domains called caveolae5,6 can entrap activated G&alpha;q 7. This entrapment has the effect of stabilizing the activated state of G&alpha;q and resulting in prolonged Ca2+ signals in cardiomyocytes and other cell types8. We uncovered this surprising result by measuring dynamic calcium responses on a fast scale in living cardiomyocytes. Briefly, cells are loaded with a fluorescent Ca2+ indicator. In our studies, we used Ca2+ Green (Invitrogen, Inc.) which exhibits an increase in fluorescence emission intensity upon binding of calcium ions. The fluorescence intensity is then recorded for using a line-scan mode of a laser scanning confocal microscope. This method allows rapid acquisition of the time course of fluorescence intensity in pixels along a selected line, producing several hundreds of time traces on the microsecond time scale. These very fast traces are transferred into excel and then into Sigmaplot for analysis, and are compared to traces obtained for electronic noise, free dye, and other controls. To dissect Ca2+ responses of different flux rates, we performed a histogram analysis that binned pixel intensities with time. Binning allows us to group over 500 traces of scans and visualize the compiled results spatially and temporally on a single plot. Thus, the slow Ca2+ waves that are difficult to discern when the scans are overlaid due to different peak placement and noise, can be readily seen in the binned histograms. Very fast fluxes in the time scale of the measurement show a narrow distribution of intensities in the very short time bins whereas longer Ca2+ waves show binned data with a broad distribution over longer time bins. These different time distributions allow us to dissect the timing of Ca2+fluxes in the cells, and to determine their impact on various cellular events.

We present a method to isolate rapid (microsecond) calcium events from slower fluxes in living cells using laser scanning confocal microscopy. The method measures fluorescence intensity fluctuations of calcium indicators by recording line scans of several hundred pixels in a cell. Histogram analysis allows us to isolate the time scales of different calcium fluxes.

心筋細胞における高速カルシウムフラックスの測定

Cardiomyocytes have multiple Ca2+ fluxes of varying duration that work together to optimize function 1,2. Changes in Ca2+ activity in response to ...

Mapping Molecular Diffusion in the Plasma Membrane by Multiple-Target Tracing (MTT)

Our goal is to obtain a comprehensive description of molecular processes occurring at cellular membranes in different biological functions. We aim at characterizing the complex organization and dynamics of the plasma membrane at single-molecule level, by developing analytic tools dedicated to Single-Particle Tracking (SPT) at high density: Multiple-Target Tracing (MTT)1. Single-molecule videomicroscopy, offering millisecond and nanometric resolution1-11, allows a detailed representation of membrane organization12-14 by accurately mapping descriptors such as cell receptors localization, mobility, confinement or interactions.
We revisited SPT, both experimentally and algorithmically. Experimental aspects included optimizing setup and cell labeling, with a particular emphasis on reaching the highest possible labeling density, in order to provide a dynamic snapshot of molecular dynamics as it occurs within the membrane. Algorithmic issues concerned each step used for rebuilding trajectories: peaks detection, estimation and reconnection, addressed by specific tools from image analysis15,16. Implementing deflation after detection allows rescuing peaks initially hidden by neighboring, stronger peaks. Of note, improving detection directly impacts reconnection, by reducing gaps within trajectories. Performances have been evaluated using Monte-Carlo simulations for various labeling density and noise values, which typically represent the two major limitations for parallel measurements at high spatiotemporal resolution.
The nanometric accuracy17 obtained for single molecules, using either successive on/off photoswitching or non-linear optics, can deliver exhaustive observations. This is the basis of nanoscopy methods17 such as STORM18, PALM19,20, RESOLFT21 or STED22,23, which may often require imaging fixed samples. The central task is the detection and estimation of diffraction-limited peaks emanating from single-molecules. Hence, providing adequate assumptions such as handling a constant positional accuracy instead of Brownian motion, MTT is straightforwardly suited for nanoscopic analyses. Furthermore, MTT can fundamentally be used at any scale: not only for molecules, but also for cells or animals, for instance. Hence, MTT is a powerful tracking algorithm that finds applications at molecular and cellular scales.

Mapping Molecular Diffusion in the Plasma Membrane by Multiple-Target Tracing MTT

Multiple-Target Tracing is a homemade algorithm developed for tracking individually labeled molecules within the plasma membrane of living cells. Efficiently detecting, estimating and tracing molecules over time at high-density provide a user-friendly, comprehensive tool to investigate nanoscale membrane dynamics.

複数のターゲットトレース（MTT）による原形質膜中の分子拡散のマッピング

Our goal is to obtain a comprehensive description of molecular processes occurring at cellular membranes in different biological functions. We aim at ...

Intravital Microscopy for Imaging Subcellular Structures in Live Mice Expressing Fluorescent Proteins

Here we describe a procedure to image subcellular structures in live rodents that is based on the use of confocal intravital microscopy. As a model organ, we use the salivary glands of live mice since they provide several advantages. First, they can be easily exposed to enable access to the optics, and stabilized to facilitate the reduction of the motion artifacts due to heartbeat and respiration. This significantly facilitates imaging and tracking small subcellular structures. Second, most of the cell populations of the salivary glands are accessible from the surface of the organ. This permits the use of confocal microscopy that has a higher spatial resolution than other techniques that have been used for in vivo imaging, such as two-photon microscopy. Finally, salivary glands can be easily manipulated pharmacologically and genetically, thus providing a robust system to investigate biological processes at a molecular level.
In this study we focus on a protocol designed to follow the kinetics of the exocytosis of secretory granules in acinar cells and the dynamics of the apical plasma membrane where the secretory granules fuse upon stimulation of the beta-adrenergic receptors. Specifically, we used a transgenic mouse that co-expresses cytosolic GFP and a membrane-targeted peptide fused with the fluorescent protein tandem-Tomato. However, the procedures that we used to stabilize and image the salivary glands can be extended to other mouse models and coupled to other approaches to label in vivo cellular components, enabling the visualization of various subcellular structures, such as endosomes, lysosomes, mitochondria, and the actin cytoskeleton.

Intravital microscopy is a powerful tool that enables imaging various biological processes in live animals. In this article, we present a detailed method for imaging the dynamics of subcellular structures, such as the secretory granules, in the salivary glands of live mice.

蛍光タンパク質を発現する生きたマウスでのイメージング細胞内の構造物の生体顕微鏡

Here we describe a procedure to image subcellular structures in live rodents that is based on the use of confocal intravital microscopy. As a model organ, ...

Imaging Plasma Membrane Deformations With pTIRFM

To gain novel insights into the dynamics of exocytosis, our group focuses on the changes in lipid bilayer shape that must be precisely regulated during the fusion of vesicle and plasma membranes. These rapid and localized changes are achieved by dynamic interactions between lipids and specialized proteins that control membrane curvature. The absence of such interactions would not only have devastating consequences for vesicle fusion, but a host of other cellular functions that involve control of membrane shape. In recent years, the identity of a number of proteins with membrane-shaping properties has been determined. What remains missing is a roadmap of when, where, and how they act as fusion and content release progress.
Our understanding of the molecular events that enable membrane remodeling has historically been limited by a lack of analytical methods that are sensitive to membrane curvature or have the temporal resolution to track rapid changes. PTIRFM satisfies both of these criteria. We discuss how pTIRFM is implemented to visualize and interpret rapid, submicron changes in the orientation of chromaffin cell membranes during dense core vesicle (DCV) fusion. The chromaffin cells we use are isolated from bovine adrenal glands. The membrane is stained with a lipophilic carbocyanine dye,1,1&#39;-dioctadecyl-3,3,3&#39;,3&#39;-tetramethylindodicarbocyanine, 4-chlorobenzenesulfonate, or&#160;diD. DiD intercalates in the membrane plane with a &#34;fixed&#34; orientation and is therefore sensitive to the polarization of the evanescent field. The diD-stained cell membrane is sequentially excited with orthogonal polarizations of a 561&#160;nm laser (p-pol, s-pol). A 488&#160;nm laser is used to visualize vesicle constituents and time the moment of fusion. Exocytosis is triggered by locally perfusing cells with a depolarizing KCl solution. Analysis is performed offline using custom-written software to understand how diD emission intensity changes relate to fusion pore dilation.

Polarization-based Total Internal Reflection Fluorescence Microscopy (pTIRFM) enables real-time detection of cell membrane dynamics. This article describes the implementation of pTIRFM for the study of membrane remodeling during regulated exocytosis. The technique is generalizable to other processes in cell biology that directly or indirectly involve changes in membrane shape.

pTIRFMによる画像形成細胞膜変形は

To gain novel insights into the dynamics of exocytosis, our group focuses on the changes in lipid bilayer shape that must be precisely regulated during ...

Functional Characterization of Na+/H+ Exchangers of Intracellular Compartments Using Proton-killing Selection to Express Them at the Plasma Membrane

Endosomal acidification is critical for a wide range of processes, such as protein recycling and degradation, receptor desensitization, and neurotransmitter loading in synaptic vesicles. This acidification is described to be mediated by proton ATPases, coupled to ClC chloride transporters. Highly-conserved electroneutral protons transporters, the Na+/H+ exchangers (NHE) 6, 7 and 9 are also expressed in these compartments. Mutations in their genes have been linked with human cognitive and neurodegenerative diseases. Paradoxically, their roles remain elusive, as their intracellular localization has prevented detailed functional characterization. This manuscript shows a method to solve this problem. This consists of the selection of mutant cell lines, capable of surviving acute cytosolic acidification by retaining intracellular NHEs at the plasma membrane. It then depicts two complementary protocols to measure the ion selectivity and activity of these exchangers: (i) one based on intracellular pH measurements using fluorescence video microscopy, and (ii) one based on the fast kinetics of lithium uptake. Such protocols can be extrapolated to measure other non-electrogenic transporters. Furthermore, the selection procedure presented here generates cells with an intracellular retention defective phenotype. Therefore these cells will also express other vesicular membrane proteins at the plasma membrane. The experimental strategy depicted here may therefore constitute a potentially powerful tool to study other intracellular proteins that will be then expressed at the plasma membrane together with the vesicular Na+/H+ exchangers used for the selection.

Functional Characterization of Na+/H+ Exchangers of Intracellular Compartments Using Proton-killing Selection to Express Them at the Plasma Membrane

The first part of this article shows how to select mutant cell lines expressing vesicular Na+/H+ exchangers at their plasma membrane. The second part provides protocols based on intracellular pH measurements and fast ion uptake, which are used to determine the ion selectivity and the kinetic parameters of these exchangers.

ナの機能的特徴<sup&gt; +</sup&gt; / H<sup&gt; +</sup細胞膜でそれらを表現するためにプロトン殺す選択を使用した細胞内区画の&gt;交換器

Endosomal acidification is critical for a wide range of processes, such as protein recycling and degradation, receptor desensitization, and ...

Determination of Plasma Membrane Partitioning for Peripherally-associated Proteins

This method provides a fast approach for the determination of plasma membrane partitioning of any fluorescently-tagged peripherally-associated protein using the profiles of fluorescence intensity across the plasma membrane. Measured fluorescence profiles are fitted by a model for membrane and cytoplasm fluorescence distribution along a line applied perpendicularly to the cell periphery. This model is constructed from the fluorescence intensity values in reference cells expressing a fluorescently-tagged marker for cytoplasm and with FM 4-64-labeled plasma membrane. The method can be applied to various cell types and organisms; however, only plasma membranes of non-neighboring cells can be evaluated. This fast microscopy-based method is suitable for experiments, where subtle and dynamic changes of plasma membrane-associated markers are expected and need to be quantified, e.g., in the analysis of mutant versions of proteins, inhibitor treatments, and signal transduction observations. The method is implemented in a multi-platform R package that is coupled with an ImageJ macro that serves as a user-friendly interface.

Here, we present a protocol to perform a quantitative analysis of the level of plasma-membrane association for fluorescently-tagged peripherally-associated protein. The method is based on the computational decomposition of membrane and cytoplasmic component of signal observed in cells labeled with plasma membrane fluorescent marker.

細胞膜の末梢関連タンパク質の分割の決定

This method provides a fast approach for the determination of plasma membrane partitioning of any fluorescently-tagged peripherally-associated protein ...

Characterization of MLKL-mediated Plasma Membrane Rupture in Necroptosis

Necroptosis is a programmed cell death pathway triggered by activation of receptor interacting protein kinase 3 (RIPK3), which phosphorylates and activates the mixed lineage kinase-like domain pseudokinase, MLKL, to rupture or permeabilize the plasma membrane. Necroptosis is an inflammatory pathway associated with multiple pathologies including autoimmunity, infectious and cardiovascular diseases, stroke, neurodegeneration, and cancer. Here, we describe protocols that can be used to characterize MLKL as the executioner of plasma membrane rupture in necroptosis. We visualize the process of necroptosis in cells using live-cell imaging with conventional and confocal fluorescence&#160;microscopy, and in fixed cells using electron microscopy, which together revealed the redistribution of MLKL from the cytosol to the plasma membrane prior to induction of large holes in the plasma membrane. We present in vitro nuclear magnetic resonance (NMR) analysis using lipids to identify putative modulators of MLKL-mediated necroptosis. Based on this method, we identified quantitative lipid-binding preferences and phosphatidyl-inositol phosphates (PIPs) as critical binders of MLKL that are required for plasma membrane targeting and permeabilization in necroptosis.

We report methods for characterization of MLKL-mediated plasma membrane rupture in necroptosis including conventional and confocal live-cell microscopy imaging, scanning electron microscopy, and NMR-based lipid binding.

ネクロトーシス MLKL を介した細胞膜破壊の解析

Necroptosis is a programmed cell death pathway triggered by activation of receptor interacting protein kinase 3 (RIPK3), which phosphorylates and ...

Simultaneous Measurements of Intracellular Calcium and Membrane Potential in Freshly Isolated and Intact Mouse Cerebral Endothelium

Cerebral arteries and their respective microcirculation deliver oxygen and nutrients to the brain via blood flow regulation. Endothelial cells line the lumen of blood vessels and command changes in vascular diameter as needed to meet the metabolic demand of neurons. Primary endothelial-dependent signaling pathways of hyperpolarization of membrane potential (Vm) and nitric oxide typically operate in parallel to mediate vasodilation and thereby increase blood flow. Although integral to coordinating vasodilation over several millimeters of vascular length, components of endothelium-derived hyperpolarization (EDH) have been historically difficult to measure. These components of EDH entail intracellular Ca2+ [Ca2+]i increases and subsequent activation of small- and intermediate conductance Ca2+-activated K+ (SKCa/IKCa) channels.
Here, we present a simplified illustration of the isolation of fresh endothelium from mouse cerebral arteries; simultaneous measurements of endothelial [Ca2+]i and Vm using Fura-2 photometry and intracellular sharp electrodes, respectively; and a continuous superfusion of salt solutions and pharmacological agents under physiological conditions (pH 7.4, 37 &#176;C). Posterior cerebral arteries from the Circle of Willis are removed free of the posterior communicating and the basilar arteries. Enzymatic digestion of cleaned posterior cerebral arterial segments and subsequent trituration facilitates removal of adventitia, perivascular nerves, and smooth muscle cells. Resulting posterior cerebral arterial endothelial &#34;tubes&#34; are then secured under a microscope and examined using a camera, photomultiplier tube, and one to two electrometers while under continuous superfusion. Collectively, this method can simultaneously measure changes in endothelial [Ca2+]i and Vm in discrete cellular locations, in addition to the spreading of EDH through gap junctions up to millimeter distances along the intact endothelium. This method is expected to yield a high-throughput analysis of the cerebral endothelial functions underlying mechanisms of blood flow regulation in the normal and diseased brain.

Demonstrated here are protocols for (1) freshly isolating intact cerebral endothelial "tubes" and (2) simultaneous measurements of endothelial calcium and membrane potential during endothelium-derived hyperpolarization. Further, these methods allow for pharmacological tuning of endothelial cell calcium and electrical signaling as individual or interactive experimental variables.

細胞内カルシウムと新鮮な分離とそのままマウス脳血管内皮細胞の膜電位の同時計測

Cerebral arteries and their respective microcirculation deliver oxygen and nutrients to the brain via blood flow regulation. Endothelial cells line the ...

Imaging Calcium Dynamics in Subpopulations of Mouse Pancreatic Islet Cells

Pancreatic islet hormones regulate blood glucose homeostasis. Changes in blood glucose induce oscillations of cytosolic calcium in pancreatic islet cells that trigger secretion of three main hormones: insulin (from &#946;-cells), glucagon (&#945;-cells) and somatostatin (&#948;-cells). &#946;-Cells, which make up the majority of islet cells and are electrically coupled to each other, respond to the glucose stimulus as one single entity. The excitability of the minor subpopulations, &#945;-cells and &#948;-cells (making up around 20% (30%) and 4% (10%) of the total rodent1 (human2) islet cell numbers, respectively) is less predictable and is therefore of special interest.
Calcium sensors are delivered into the peripheral layer of cells within the isolated islet. The islet or a group of islets is then immobilized and imaged using a fluorescence microscope. The choice of the imaging mode is between higher throughput (wide-field) and better spatial resolution (confocal). Conventionally, laser scanning confocal microscopy is used for imaging tissue, as it provides the best separation of the signal between the neighboring cells. A wide-field system can be utilized too, if the contaminating signal from the dominating population of &#946;-cells is minimized.
Once calcium dynamics in response to specific stimuli have been recorded, data are expressed in numerical form as fluorescence intensity vs. time, normalized to the initial fluorescence and baseline-corrected, to remove the effects linked to bleaching of the fluorophore. Changes in the spike frequency or partial area under the curve (pAUC) are computed vs. time, to quantify the observed effects. pAUC is more sensitive and quite robust whereas spiking frequency provides more information on the mechanism of calcium increase.
Minor cell subpopulations can be identified using functional responses to marker compounds, such as adrenaline and ghrelin, that induce changes in cytosolic calcium in a specific populations of islet cells.

Here, we present a protocol for imaging and quantifying calcium dynamics in heterogeneous cell populations, such as pancreatic islet cells. Fluorescent reporters are delivered into the peripheral layer of cells within the islet, which is then immobilized and imaged, and per-cell analysis of the dynamics of fluorescence intensity is performed.

マウス膵島細胞の亜集団におけるカルシウムダイナミクスのイメージング

Pancreatic islet hormones regulate blood glucose homeostasis. Changes in blood glucose induce oscillations of cytosolic calcium in pancreatic islet cells ...