The video demonstrates a protocol for preparing and transfecting small interfering RNA (siRNA) into cells using RNAiMAX reagent. It details the steps for diluting siRNA, adding it to a 384-well microplate, and ensuring proper mixing for effective transfection in a cellular environment.

preparation of sirna mixture for mitochondrial dna synthesis

mtDNA의 합성 및 분포에 대한 고처리량 정량화

For most eukaryotic cells mitochondria are essential organelles, as they play a crucial role in numerous cellular processes. First and foremost, mitochondria are the key energy suppliers of cells1. Mitochondria are also involved in regulating cellular homeostasis (for instance, intracellular redox2 and the calcium balance3), cell signaling4,5, apoptosis6, the synthesis of different biochemical compounds7,8, and the innate immune response9. Mitochondrial dysfunction is associated with various pathological states and human diseases10. 
The functioning of mitochondria depends on the genetic information located in two separate genomes: the nuclear and mitochondrial genomes. The mitochondrial genome encodes a small number of genes compared to the nuclear genome, but all the mtDNA-encoded genes are essential for human life. The mitochondrial protein machinery necessary to maintain the mtDNA is encoded by nDNA. The basic components of the mitochondrial replisome, as well as some mitochondrial biogenesis factors, have already been identified (reviewed in previous research11,12). However, mitochondrial DNA replication and maintenance mechanisms are still far from being understood. In contrast to nDNA, the mitochondrial genome exists in multiple copies, which provides an additional layer for regulating mitochondrial gene expression. Much less is currently known about the distribution and segregation of mtDNA within organelles, to what extent these processes are regulated, and if they are, which proteins are involved13. The segregation pattern is crucial when cells contain a mixed population of wild-type and mutated mtDNA. Their unequal distribution may lead to the generation of cells with a detrimental amount of mutated mtDNA.
So far, the protein factors necessary for mtDNA maintenance have been identified mainly by biochemical methods, bioinformatic analyses, or through disease-associated studies. In this work, in order to ensure a high chance of identifying factors that have previously escaped identification, a different strategy is described. The method is based on the labeling of mtDNA during replication or repair with 5-bromo-2'-deoxyuridine (BrdU), a nucleoside analog of thymidine. BrdU is readily incorporated into nascent DNA strands during DNA synthesis and, in general, is used for monitoring the replication of nuclear DNA14. However, the procedure developed here has been optimized for detecting BrdU incorporated into mtDNA using the immunofluorescence of anti-BrdU antibodies.
The approach allows for the high-throughput quantification of mtDNA synthesis and distribution in human cells cultured in vitro. A high-throughput strategy is necessary to conduct tests under different experimental conditions in a relatively short time; therefore, it is proposed in the protocol to utilize a multi-well format for cell culturing and automated fluorescence microscopy for imaging. The protocol includes the transfection of human HeLa cells with an siRNA library and the subsequent monitoring of mtDNA replication or repair using the metabolic labeling of newly synthesized DNA with BrdU. This approach is combined with immunostaining of the DNA with the help of anti-DNA antibodies. Both parameters are analyzed using quantitative fluorescence microscopy. Additionally, mitochondria are visualized with a specific dye. To demonstrate the specificity of the protocol, BrdU staining was tested on cells devoid of mtDNA (rho0 cells), on HeLa cells upon the silencing of well-known mtDNA maintenance factors, and on HeLa cells after treatment with an mtDNA replication inhibitor. The mtDNA levels were also measured by an independent method, namely qPCR.

저자 스포트라이트: 미토콘드리아 DNA 합성 및 분포의 고처리량 이미지 기반 정량화  

미토콘드리아 DNA 합성 및 분포의 고처리량 이미지 기반 정량화

Watch this Scientific Journal Video about Preparation of siRNA Mixture for Mitochondrial DNA Synthesis at JoVE.com

Preparation of siRNA Mixture for Mitochondrial DNA Synthesis  

미토콘드리아 DNA 합성을 위한 siRNA 혼합물의 제조

먼저, siRNA를 최적 배지에 희석하여 작은 간섭 RNA 또는 siRNA의 140 나노몰 믹스를 준비한다. 희석된 혼합물 5 마이크로리터를 흑색 384 웰 세포 배양 마이크로플레이트의 웰에 첨가한다. 최적 배지에서 적절한 양의 RNAiMAX 형질주입 시약 용액을 준비하고, 시약 디스펜서를 사용하여 384 웰 플레이트의 각 웰에 10 마이크로리터를 첨가한다.

preparation-of-sirna-mixture-for-mitochondrial-dna-synthesis

Research

JoVE Journal

Biochemistry

Preparation of siRNA Mixture for Mitochondrial DNA Synthesis

169 조회수. 먼저, siRNA를 최적 배지에 희석하여 작은 간섭 RNA 또는 siRNA의 140 나노몰 믹스를 준비한다. 희석된 혼합물 5 마이크로리터를 흑색 384 웰 세포 배양 마이크로플레이트의 웰에 첨가한다. 최적 배지에서 적절한 양의 RNAiMAX 형질주입 시약 용액을 준비하고, 시약 디스펜서를 사용하여 384 웰 플레이트의 각 웰에 10 마이크로리터를 첨가한다.

비디오: Preparation of siRNA Mixture for Mitochondrial DNA Synthesis  

High-Throughput Image-Based Quantification of Mitochondrial DNA Synthesis and Distribution

The vast majority of cellular processes require a continuous supply of energy, the most common carrier of which is the ATP molecule. Eukaryotic cells produce most of their ATP in the mitochondria by oxidative phosphorylation. Mitochondria are unique organelles because they have their own genome that is replicated and passed on to the next generation of cells. In contrast to the nuclear genome, there are multiple copies of the mitochondrial genome in the cell. The detailed study of the mechanisms responsible for the replication, repair, and maintenance of the mitochondrial genome is essential for understanding the proper functioning of mitochondria and whole cells under both normal and disease conditions. Here, a method that allows the high-throughput quantification of the synthesis and distribution of mitochondrial DNA (mtDNA) in human cells cultured in vitro is presented. This approach is based on the immunofluorescence detection of actively synthesized DNA molecules labeled by 5-bromo-2'-deoxyuridine (BrdU) incorporation and the concurrent detection of all the mtDNA molecules with anti-DNA antibodies. Additionally, the mitochondria are visualized with specific dyes or antibodies. The culturing of cells in a multi-well format and the utilization of an automated fluorescence microscope make it easier to study the dynamics of mtDNA and the morphology of mitochondria under a variety of experimental conditions in a relatively short time.

A procedure for studying the dynamics of mitochondrial DNA (mtDNA) metabolism in cells using a multi-well plate format and automated immunofluorescence imaging to detect and quantify mtDNA synthesis and distribution is described. This can be further used to investigate the effects of various inhibitors, cellular stresses, and gene silencing on mtDNA metabolism.

The vast majority of cellular processes require a continuous supply of energy, the most common carrier of which is the ATP molecule. Eukaryotic cells ...