Project description:The objective is to identify genes that are differentially expressed following the introduction of DNA double-strand breaks (DSBs) by the Rag proteins in murine pre-B cells. Cells lacking Artemis are used since the Rag-induced DSBs will not be repaired, and thus, will provide a continuous stimulus to the cell. Murine v-abl-transformed pre-B cells were treated with 3 uM STI571 for 48 hours. Cell types included RAG-2-deficient (3 biological replicates) and Artemis-deficient (3 biological replicates) G1-phase pre-B cells. Each sample was hybridized once using Affymetrix Mouse Genome 2.0 GeneChip arrays (Mouse 430 v2, Affymetrix, Santa Clara, CA). Data were analyzed using the RAG-2-deficient samples as the controls.
Project description:The objective of this set of samples is to identify genes that are differentially expressed following the introduction of DNA double strand breaks (DSBs) by ionizing radiation in wild-type murine pre-B cells. The data generated in this project will be compared to the data generated in GSE9024, in which genes that are differentially expressed following the introduction of DNA double strand breaks (DSBs) by the Rag proteins in murine pre-B cells were examined. In order to understand the differences between the physiologic and genotoxic responses to DSB DNA damage, we need to compare cells that are all in the same compartment of the cell cycle. We are therefore examining the response to IR-induced damage in cells that are arrested in G1, which would correspond to our previous study of G1 arrested cells with Rag-induced breaks. This will illuminate the difference directly, allowing us to better understand the signaling responses to the different types of DNA damage.
Project description:The objective of this set of samples is to identify genes that are differentially expressed following the introduction of DNA double strand breaks (DSBs) by ionizing radiation in wild-type murine pre-B cells. The data generated in this project will be compared to the data generated in GSE9024, in which genes that are differentially expressed following the introduction of DNA double strand breaks (DSBs) by the Rag proteins in murine pre-B cells were examined. In order to understand the differences between the physiologic and genotoxic responses to DSB DNA damage, we need to compare cells that are all in the same compartment of the cell cycle. We are therefore examining the response to IR-induced damage in cells that are arrested in G1, which would correspond to our previous study of G1 arrested cells with Rag-induced breaks. This will illuminate the difference directly, allowing us to better understand the signaling responses to the different types of DNA damage. Murine v-abl-transformed pre-B cells were treated with 3 uM STI571 for 48 hours. The cell type is Wild type (3 biological replicates). For each wild type cell line, cells were treated with 1 Gy ionizing radiation or no ionizing radiation. Each sample was hybridized once using Affymetrix Mouse Genome 2.0 GeneChip arrays (Mouse 430 v2, Affymetrix, Santa Clara, CA). Data were analyzed using the unirradiated samples as the controls.
Project description:The objective is to identify genes that are differentially expressed following the introduction of DNA double-strand breaks (DSBs) by the Rag proteins in murine pre-B cells. Cells lacking Artemis are used since the Rag-induced DSBs will not be repaired, and thus, will provide a continuous stimulus to the cell.
Project description:DNA double strand breaks (DSBs) in B lymphocytes are thought to arise stochastically during replication (S phase) or as a result of targeted DNA damage by activation induced cytidine deaminase (AID) in G1. Here we identify a novel class of recurrent, early replicating and AID independent DNA lesions, termed early replication fragile sites (ERFS), by genome-wide localization of DNA repair proteins DNA double strand breaks (DSBs) in B lymphocytes are thought to arise stochastically during replication (S phase) or as a result of targeted DNA damage by activation induced cytidine deaminase (AID) in G1. Here we identify a novel class of recurrent, early replicating and AID independent DNA lesions, termed early replication fragile sites (ERFS), by genome-wide localization of DNA repair proteins DNA double strand breaks (DSBs) in B lymphocytes are thought to arise stochastically during replication (S phase) or as a result of targeted DNA damage by activation induced cytidine deaminase (AID) in G1. Here we identify a novel class of recurrent, early replicating and AID independent DNA lesions, termed early replication fragile sites (ERFS), by genome-wide localization of DNA repair proteins RPA, SMC5, gamma-H2AX, and BRCA1 in B cells subjected to replication stress.
Project description:DNA double strand breaks (DSBs) in B lymphocytes are thought to arise stochastically during replication (S phase) or as a result of targeted DNA damage by activation induced cytidine deaminase (AID) in G1. Here we identify a novel class of recurrent, early replicating and AID independent DNA lesions, termed early replication fragile sites (ERFS), by genome-wide localization of DNA repair proteins DNA double strand breaks (DSBs) in B lymphocytes are thought to arise stochastically during replication (S phase) or as a result of targeted DNA damage by activation induced cytidine deaminase (AID) in G1. Here we identify a novel class of recurrent, early replicating and AID independent DNA lesions, termed early replication fragile sites (ERFS), by genome-wide localization of DNA repair proteins DNA double strand breaks (DSBs) in B lymphocytes are thought to arise stochastically during replication (S phase) or as a result of targeted DNA damage by activation induced cytidine deaminase (AID) in G1. Here we identify a novel class of recurrent, early replicating and AID independent DNA lesions, termed early replication fragile sites (ERFS), by genome-wide localization of DNA repair proteins RPA, SMC5, gamma-H2AX, and BRCA1 in B cells subjected to replication stress. Protein-DNA association for four DNA damage response proteins (RPA, SMC5, g-H2AX, BRCA1), BrdU incorporation, and gene transcription in B lymphocytes with and without hydroxyurea treatment were examined.
Project description:Pre-B cell receptor (pre-BCR) signals initiate immunoglobulin light (Igl) chain gene assembly leading to RAG-mediated DNA double-strand breaks (DSBs). These signals also promote cell cycle entry, which could cause aberrant DSB repair and genome instability in pre-B cells. Here we show that RAG DSBs inhibit pre-BCR signals through the ATM- and NF-κB2-dependent induction of SPIC, a hematopoietic-specific transcriptional repressor. SPIC inhibits expression of the SYK tyrosine kinase and BLNK adaptor to prevent the pre-BCR from inducing additional Igl chain gene rearrangements and driving pre-B cells with RAG DSBs into cycle. We propose that pre-B cells toggle between pre-BCR signals and this RAG DSB-dependent checkpoint to maintain genome stability while iteratively assembling Igl chain genes.
Project description:The objective is to identify genes that are differentially expressed following the introduction of DNA double strand breaks (DSBs) by the Rag proteins in murine pre-B cells. Cells lacking Artemis are used since the Rag-induced DSBs will not be repaired and, thus, will provide a continuous stimulus to the cell. Cells lacking Artemis and Atm are used to determine which gene expression changes depend on Atm and cells lacking Artemis that express an I kappa B alpha dominant negative are used to determine which gene expression changes depend on NFkB.
Project description:Pre-B cell receptor (pre-BCR) signals initiate immunoglobulin light (Igl) chain gene assembly leading to RAG-mediated DNA double-strand breaks (DSBs). These signals also promote cell cycle entry, which could cause aberrant DSB repair and genome instability in pre-B cells. Here we show that RAG DSBs inhibit pre-BCR signals through the ATM- and NF-κB2-dependent induction of SPIC, a hematopoietic-specific transcriptional repressor. SPIC inhibits expression of the SYK tyrosine kinase and BLNK adaptor to prevent the pre-BCR from inducing additional Igl chain gene rearrangements and driving pre-B cells with RAG DSBs into cycle. We propose that pre-B cells toggle between pre-BCR signals and this RAG DSB-dependent checkpoint to maintain genome stability while iteratively assembling Igl chain genes. Three independent IL-7 cultures for each genotype (Rag1-/-:μIgH:Bcl2, Art-/-:μIgH:Bcl2 and Art-/-:Nfkb2-/-:μIgH:Bcl2) were withdrawn from IL-7 for 2 days. RNA was isolated using RNeasy (Qiagen). Gene expression profiling was performed using Illumina MouseRef-8 expression microarrays.