isolation of enriched mitochondrial fractions from cell cultures and small animal tissue samples for gel activity assays

Supercomplex 분석을 위한 작은 조직 샘플의 미토콘드리아 분획

Supercomplexes (SCs) are supramolecular associations between individual respiratory chain complexes1,2. Since the initial identification of SCs and the description of their composition by the group of Sch&#228;gger2,3, later confirmed by other groups, it was established that they contain respiratory complexes I, III, and IV (CI, CIII, and CIV, respectively) in different stoichiometries. Two main populations of SCs can be defined, those containing CI (and either CIII alone or CIII and CIV) and with very high molecular weight (MW, starting ~1.5 MDa for the smaller SC: CI + CIII2) and those containing CIII and CIV but not CI, with much smaller size (such as CIII2 + CIV with ~680 kDa). These SCs coexist in the inner mitochondrial membrane with free complexes, also in different proportions. Thus, while CI is mostly found in its associated forms (that is, in SCs: ~80% in bovine heart and more than 90% in many human cell types)3, CIV is very abundant in its free form (more than 80% in bovine heart), with CIII showing a more balanced distribution (~40% in its more abundant free form, as a dimer, in bovine heart).
While their existence is now generally accepted, their precise role is still under debate4,5,6,7,8,9,10. According to the plasticity model, different proportions of SCs and individual complexes can exist depending on the cell type or the metabolic status1,7,11. This dynamic nature of the assembly would allow cells to regulate the use of available fuels and the efficiency of the oxidative phosphorylation (OXPHOS) system in response to environmental changes4,5,7. SCs could also contribute to control the reactive oxygen species generation rate and participate in the stabilization and turnover of individual complexes4,12,13,14. Modifications of the SC assembly status have been described in association with different physiological and pathological situations15,16 and with the aging process17.
Thus, changes in the SC patterns have been described in yeast depending on the carbon source used for growth2&#160;and in cultured mammalian cells when glucose is substituted by galactose4. Modifications have also been reported in mouse liver after fasting8 and in astrocytes when mitochondrial fatty acid oxidation is blocked18. In addition, a decrease or alterations in SCs and OXPHOS have been found in Barth syndrome19, heart failure20, several metabolic21 and neurological22,23,24 disorders, and different tumors25,26,27,28. Whether these alterations in SC assembly and levels are a primary cause or represent secondary effects in these pathological situations is still under investigation15,16. Different methodologies can give information about the assembly and function of SCs; these include activity measurements8,29, ultrastructural analysis30,31, and proteomics32,33. A useful alternative that is increasingly being employed and is the starting point for some of the previously mentioned methodologies is the direct determination of SC assembly status by Blue native (BN) electrophoresis developed for this purpose by Sch&#228;gger&#39;s group34,35.
This approach requires reproducible and efficient procedures to obtain and solubilize mitochondrial membranes and can be complemented by other techniques such as in-gel activity analysis (IGA), second-dimension electrophoresis, and western blot (WB). A limitation in the studies on SC dynamics by BN electrophoresis can be the amount of starting cells or tissue samples. We present a series of protocols for the analysis of SC assembly and function, adapted from Sch&#228;gger&#39;s group methods, that can be applied to fresh or frozen cell or tissue samples starting from as little as 20 mg of tissue.

저자 스포트라이트: Unveiling Oxidative Phosphorylation System Dynamics and Mitochondrial Roles in Health and Disease

Isolation of Mitochondria for Mitochondrial Supercomplex Analysis from Small Tissue and Cell Culture Samples(소조직 및 세포 배양 샘플에서 미토콘드리아 초복합체 분석을 위한 미토콘드리아 분리) 

Our research is focused on better understanding mitochondrial biogenesis, in particular, the OXPHOS System organization and Regulation, and also on defining the role that mitochondria play in diseases from cancer to neurodegenerative disorders. Mitochondria perform multiple and essential roles in the cell, conditioning its whole metabolism and survival. We're slowly increasing our knowledge of mitochondrial complexity, and its contribution to cell adaptation mechanisms in health and disease.We have contributed to establish a new organization model for the OXPHOS system, the plasticity model that integrates previous proposals and assumes the coexistence of super complexes and free complexes in different proportions to optimize its function and allow cellular adaptations. Our protocol allows starting from small tissues or cell culture samples to obtain enough mitochondrial protein amounts to analyze super complexes assembly and status and function by blue native electrophoresis or other techniques. We can do this reproducibly in a short time with a simple equipment and relatively with low costs.

Isolation of Enriched Mitochondrial Fractions from Cell Cultures and Small Animal Tissue Samples for Gel Activity Assay(겔 활성 분석을 위한 세포 배양 및 소동물 조직 샘플에서 농축된 미토콘드리아 분획 분리)

먼저, 충전된 세포 펠릿을 세포 펠릿 부피의 7배에 해당하는 저긴장성 완충액에 재현탁시킵니다. 세포 현탁액을 Potter-Dounce 균질화기로 옮기고 세포가 부풀어 오르도록 얼음 위에서 2분 동안 배양합니다. 600RPM으로 회전하는 모터 구동 테프론 유봉에 연결된 균질기에서 8-10 스트로크를 수행하여 세포막을 파괴합니다.세포 현탁액에 동일한 부피의 고긴장성 완충액을 추가하여 등장성 환경을 생성합니다. 균질액을 10-15밀리리터 튜브에 옮깁니다. 섭씨 4도에서 5분 동안 1, 000G에서 원심분리기를 하고 상층액을 1.5밀리리터 폴리프로필렌 튜브에 집어넣습니다.미토콘드리아 조잡한 분획을 모으기 위하여는, 16에 microfuge, 4 섭씨 온도에 2 분 동안 000G에 있는 분리기. 상층액을 버리고 미토콘드리아 농축 펠릿에 0.5밀리리터의 완충액을 재현탁시킵니다. A. 앞에서 설명한 것처럼 두 튜브의 내용물을 하나로 결합하고 원심분리합니다. 마지막 원심분리 후 펠릿을 300마이크로리터의 완충액에 재현탁시킵니다. A. Bradford 분석을 사용하여 미토콘드리아 단백질 농도를 정량화합니다.가위를 사용하여 20-30 밀리그램의 동물 조직을 자릅니다. 여과기를 사용하여 균질화 완충액에서 조직을 3-4회 세척하고 작은 조각이 손실되지 않도록 주의하십시오. 완충액이 있는 조직 조각을 균질화기로 옮깁니다.간, 비장 및 신장 조직의 경우 LVM Potter에서 600RPM의 모터 구동 테프론 유봉을 사용하여 4-6개의 위아래 스트로크를 수행합니다.

isolation-enriched-mitochondrial-fractions-from-cell-cultures-small

Research

JoVE Journal

Biochemistry

Isolation of Enriched Mitochondrial Fractions from Cell Cultures and Small Animal Tissue Samples for Gel Activity Assays

134 조회수.  University of Zaragoza. 먼저, 충전된 세포 펠릿을 세포 펠릿 부피의 7배에 해당하는 저긴장성 완충액에 재현탁시킵니다. 세포 현탁액을 Potter-Dounce 균질화기로 옮기고 세포가 부풀어 오르도록 얼음 위에서 2분 동안 배양합니다. 600RPM으로 회전하는 모터 구동 테프론 유봉에 연결된 균질기에서 8-10 스트로크를 수행하여 세포막을 파괴합니다.세포 현탁액에 동일한 부피의 고긴장성 완충액을 추가?...

비디오: Isolation of Enriched Mitochondrial Fractions from Cell Cultures and Small Animal Tissue Samples for Gel Activity Assay(겔 활성 분석을 위한 세포 배양 및 소동물 조직 샘플에서 농축된 미토콘드리아 분획 분리)

Isolation of Mitochondria for Mitochondrial Supercomplex Analysis from Small Tissue and Cell Culture Samples 

Over the last decades, the evidence accumulated about the existence of respiratory supercomplexes (SCs) has changed our understanding of the mitochondrial electron transport chain organization, giving rise to the proposal of the "plasticity model." This model postulates the coexistence of different proportions of SCs and complexes depending on the tissue or the cellular metabolic status. The dynamic nature of the assembly in SCs would allow cells to optimize the use of available fuels and the efficiency of electron transfer, minimizing reactive oxygen species generation and favoring the ability of cells to adapt to environmental changes. 
More recently, abnormalities in SC assembly have been reported in different diseases such as neurodegenerative disorders (Alzheimer's and Parkinson's disease), Barth Syndrome, Leigh syndrome, or cancer. The role of SC assembly alterations in disease progression still needs to be confirmed. Nevertheless, the availability of enough amounts of samples to determine the SC assembly status is often a challenge. This happens with biopsy or tissue samples that are small or have to be divided for multiple analyses, with cell cultures that have slow growth or come from microfluidic devices, with some primary cultures or rare cells, or when the effect of particular costly treatments has to be analyzed (with nanoparticles, very expensive compounds, etc.). In these cases, an efficient and easy-to-apply method is required. This paper presents a method adapted to obtain enriched mitochondrial fractions from small amounts of cells or tissues to analyze the structure and function of mitochondrial SCs by native electrophoresis followed by in-gel activity assays or western blot.

This protocol describes a technique for the analysis of respiratory supercomplexes when only small amounts of samples are available.

Over the last decades, the evidence accumulated about the existence of respiratory supercomplexes (SCs) has changed our understanding of the mitochondrial ...