preparation and transfection of hek-293t cells for facs sorting analysis

Análise FACS de células repórter GFP e mCherry para avaliar a eficiência de NHEJ e RH

A DNA double-strand break (DSB) is the most deleterious form of DNA damage, potentially leading to genome instability, chromosomal rearrangements, cellular senescence, and cell death if not repaired promptly1. Two well-established pathways, nonhomologous end joining (NHEJ) and homologous recombination (HR), are recognized for their effectiveness in addressing DNA DSBs2,3. HR is considered an error-free mechanism for DSB repair, utilizing homologous sequences in the sister chromatid as a template to restore the original configuration of the injured DNA molecule3. NHEJ, on the other hand, is an error-prone DSB repair pathway that joins the broken DNA ends without relying on any template2.
The NHEJ assay and HR assay are classical methods originally developed in Jasin&#39;s laboratory at Memorial Sloan-Kettering Cancer Center and utilized to quantify the efficiency of NHEJ and HR, respectively4,5,6,7. These assays play a crucial role in investigating the relevant mechanisms and factors associated with NHEJ and HR8,9,10,11,12,13,14. Both assays rely on the implementation of two disrupted GFP reporters, EJ5-GFP and DR-GFP, to monitor the repair of DSBs induced by the I-SceI endonuclease. The EJ5-GFP reporter is employed in the NHEJ assay, while the DR-GFP reporter is utilized in the HR assay. Each reporter is subtly designed so that the I-SceI-induced DSBs can only be repaired by a specific repair pathway to restore a GFP expression cassette4,5.
The NHEJ assay and HR assay can be conducted using either a chromosomally integrated or an extrachromosomal approach15,16. The chromosomally integrated approach necessitates the integration of the disrupted GFP reporters into the genome, allowing the analysis of DSB repair within a chromosomal context6,15. However, this approach requires prolonged cell passaging and is unsuitable for comparative studies involving multiple cell lines due to arbitrary chromosomal integration, introducing an additional confounding factor apart from inherent differences. In this protocol, we describe the extrachromosomal NHEJ assay and HR assays, involving the transient transfection of the disrupted GFP and I-SceI plasmids into HEK-293T cells, followed by flow cytometry analysis (the experiment workflow is shown in Figure 1). These non-integrated reporter assays were originally reported by Jasin&#39;s laboratory to study DNA interstrand cross-links repair16 and have been employed to assess NHEJ efficiency and HR efficiency by several laboratories9,10,11,12,13,14,17,18,19, including ours11. These extrachromosomal approaches facilitate the analysis of DSB repair in comparative studies involving multiple established stable cell lines.

Autor em destaque: Decodificando o reparo do DNA por ensaio NHEJ extracromossômico e ensaios HR

Análise da Eficiência de Junção de Extremidade Não Homóloga e Recombinação Homóloga em Células HEK-293T Usando Sistemas Reporter Baseados em GFP

DNA double-strand breaks represent the most perilous DNA lesions. In response, cells employ two primary mechanisms for DNA double-strand break repair, NHEJ and HR.Quantifying the efficiency of NHEJ and HR separately is crucial for exploring the relevant mechanisms and factors associated with them. The NHEJ assay and the HR assay are established methods used to measure the efficiency of NHEJ and HR.These methods rely on meticulously designed plasmids that contain a disrupted green fluorescent protein gene with recognition sites for endonuclease I-SceI for induction of DSBs.The NHEJ assay and the HR assay can be conducted using is a chromosomally-integrated or a extrachromosomal approach. The chromosomally-integrated approach enables the analysis of DSB repair within a chromosomally contest. However, the chromosomally integrated approach requires prolonged cell and is unsuitable for comparative studies involving multiple cell lines.In this protocol, we describe the extrachromosomal NHEJ and HR assays involving transient transfection of the disrupted GFP and I-SceI plasmids into HEK-293T cells and subsequent flow cytometry analysis. These nonintegrated reporter assays have been employed to assess the NHEJ efficiency and HR efficiency by several labs, including ours. In contrast to the chromosomally-integrated approach, this extrachromosomal approach enables swift analysis of the NHEJ or HR efficiency through the utilization of established, stable cell lines.

Preparação e transfecção de células HEK-293T para análise de classificação FACS

Comece cultivando células T HEK 293 em meio DMEM, suplementado com soro bovino fetal a 10%. No dia anterior à transfecção, semeie células T HEK 293 em uma placa de seis poços para atingir aproximadamente 60% de confluência no dia seguinte. Em seguida, transfecte as células da amostra experimental em uma placa de seis poços com plasmídeos para ensaio NHEJ ou HR usando um kit de transfecção comercial.Para controles de calibração de facs, deixe um poço de células não transfectadas como controle negativo. Transfectar as células em uma placa de seis poços com plasmídeos para GFP, controle de cor única, ou mCherry, controle de cor única.

preparation-transfection-hek-293t-cells-for-facs-sorting

Research

JoVE Journal

Biology

Preparation and Transfection of HEK-293T Cells for FACS Sorting Analysis

129 visualizações.  Qiqihar Medical University. Comece cultivando células T HEK 293 em meio DMEM, suplementado com soro bovino fetal a 10%. No dia anterior à transfecção, semeie células T HEK 293 em uma placa de seis poços para atingir aproximadamente 60% de confluência no dia seguinte. Em seguida, transfecte as células da amostra experimental em uma placa de seis poços com plasmídeos para ensaio NHEJ ou HR usando um kit de transfecção comercial.Para controles de calibração de facs, deixe um poço de células não tran...

Vídeo: Preparação e transfecção de células HEK-293T para análise de classificação FACS

Analysis of Nonhomologous End Joining and Homologous Recombination Efficiency in HEK-293T Cells Using GFP-Based Reporter Systems

DNA double-strand breaks (DSBs) represent the most perilous DNA lesions, capable of inducing substantial genetic information loss and cellular demise. In response, cells employ two primary mechanisms for DSB repair: nonhomologous end joining (NHEJ) and homologous recombination (HR). Quantifying the efficiency of NHEJ and HR separately is crucial for exploring the relevant mechanisms and factors associated with each. The NHEJ assay and HR assay are established methods used to measure the efficiency of their respective repair pathways. These methods rely on meticulously designed plasmids containing a disrupted green fluorescent protein (GFP) gene with recognition sites for endonuclease I-SceI, which induces DSBs. Here, we describe the extrachromosomal NHEJ assay and HR assay, which involve co-transfecting HEK-293T cells with EJ5-GFP/DR-GFP plasmids, an I-SceI expressing plasmid, and an mCherry expressing plasmid. Quantitative results of NHEJ and HR efficiency are obtained by calculating the ratio of GFP-positive cells to mCherry-positive cells, as counted by flow cytometry. In contrast to chromosomally integrated assays, these extrachromosomal assays are more suitable for conducting comparative investigations involving multiple established stable cell lines.

This protocol describes an extrachromosomal nonhomologous end joining (NHEJ) assay and homologous recombination (HR) assay to quantify the efficiency of NHEJ and HR in HEK-293T cells.

DNA double-strand breaks (DSBs) represent the most perilous DNA lesions, capable of inducing substantial genetic information loss and cellular demise. In ...