The video explains a method for labeling mitochondria in HeLa cells using BrdU to detect newly synthesized DNA. It details the preparation of a BrdU solution, the addition of a tracking dye, and incubation steps, highlighting the specific detection of BrdU signals in treated cells compared to untreated controls.

5-bromo-2&#39;-deoxyuridine (brdu) labeling of mitochondrial dna in hela cells

Cuantificación de alto rendimiento de la síntesis y distribución de ADNmt

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.

Autor destacado: Cuantificación basada en imágenes de alto rendimiento de la síntesis y distribución del ADN mitocondrial  

Cuantificación basada en imágenes de alto rendimiento de la síntesis y distribución del ADN mitocondrial

Watch this Scientific Journal Video about 5-Bromo-2'-Deoxyuridine BrdU Labeling of Mitochondrial DNA in HeLa Cells at JoVE.com

5-Bromo-2'-Deoxyuridine (BrdU) Labeling of Mitochondrial DNA in HeLa Cells  

Etiquetado de 5-Bromo-2&#39;-desoxiuridina (BrdU) del ADN mitocondrial en células HeLa

Para comenzar el etiquetado de las mitocondrias, prepare una solución de 20 micromolares de BrdU en DMEM con 10% de suero bovino fetal o FBS. Luego agregue el tinte de seguimiento de las mitocondrias para ajustar la concentración final a 1.1 micromolar. Después de 15 horas, agregue 10 microlitros de la solución de colorante de seguimiento de mitocondrias a los pocillos que contienen la suspensión de células HeLa.Incubar las células durante una hora. Las condiciones utilizadas para marcar moléculas de ADN recién sintetizadas con BrdU permitieron la detección de ADN marcado con BrdU en las mitocondrias de las células HeLa. La señal obtenida con anticuerpos anti-BrdU fue específica y solo se observó en células tratadas con BrdU.Independientemente del tratamiento con BrdU, no se detectó ninguna señal de anticuerpos anti-BrdU o anti-ADN en las mitocondrias de las células de la fila cero. La cuantificación de la señal fluorescente de los anticuerpos anti-BrdU indicó que las células de la fila cero tratadas con BrdU mostraron el mismo nivel bajo de fluorescencia que las células BrdU no tratadas, mientras que la señal para las líneas parentales A549 y HeLa fue 50 veces mayor.

5-bromo-2-deoxyuridine-brdu-labeling-mitochondrial-dna-hela

Research

JoVE Journal

Biochemistry

5-Bromo-2&#39;-Deoxyuridine (BrdU) Labeling of Mitochondrial DNA in HeLa Cells

286 vistas. Para comenzar el etiquetado de las mitocondrias, prepare una solución de 20 micromolares de BrdU en DMEM con 10% de suero bovino fetal o FBS. Luego agregue el tinte de seguimiento de las mitocondrias para ajustar la concentración final a 1.1 micromolar. Después de 15 horas, agregue 10 microlitros de la solución de colorante de seguimiento de mitocondrias a los pocillos que contienen la suspensión de células HeLa.Incubar las células durante una hora. Las condiciones utilizadas pa...

Video: 5-Bromo-2'-Deoxyuridine (BrdU) Labeling of Mitochondrial DNA in HeLa Cells  

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 ...