Ab V genes in mice deficient for the postreplication mismatch repair factor MutS homolog (MSH2) have been reported to display an abnormal bias for hypermutations at G and C nucleotides and hotspots. We previously showed that the germinal center (GC) response is severely attenuated in MSH2-deficient mice. This suggested that premature death of GC B cells might preclude multiple rounds of hypermutation necessary to generate a normal spectrum of base changes. To test this hypothesis, we created MSH2-deficient mice in which Bcl-2 expression was driven in B cells from a transgene. In such mice, the elevated levels of intra-GC apoptosis and untimely GC dissolution characteristic of MSH2-deficient mice are suppressed. However, the spectrum of hypermutation is unchanged. These data indicate that the effects of MSH2 deficiency on GC B cell viability and the hypermutation process are distinct.
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http://dx.doi.org/10.4049/jimmunol.169.7.3819 | DOI Listing |
Unlabelled: Lynch syndrome (LS) is defined by inherited mutations in DNA mismatch repair genes, including and carries 60% lifetime risk of developing endometrial cancer (EC). Beyond hypermutability, specific mechanisms for LS-associated endometrial carcinogenesis are not well understood. Here, we assessed the effects of MSH2 loss on EC pathogenesis using a novel mouse model (PR-Cre , abbreviated Msh2KO), primary cell lines established from this model, human tissues, and human EC cell lines with isogenic MSH2 knockdown.
View Article and Find Full Text PDFCancer Prev Res (Phila)
July 2024
Division of Gastroenterology and Hepatology, Department of Internal Medicine 3, Medical University of Vienna, Vienna, Austria.
Lynch syndrome (LS) is the most prevalent heritable form of colorectal cancer. Its early onset and high lifetime risk for colorectal cancer emphasize the necessity for effective chemoprevention. NFE2L2 (NRF2) is often considered a potential druggable target, and many chemopreventive compounds induce NRF2.
View Article and Find Full Text PDFJ Immunol
February 2023
Biology PhD Program, The Graduate Center, The City University of New York, New York, NY.
Class-switch recombination (CSR) produces secondary Ig isotypes and requires activation-induced cytidine deaminase (AID)-dependent DNA deamination of intronic switch regions within the IgH (Igh) gene locus. Noncanonical repair of deaminated DNA by mismatch repair (MMR) or base excision repair (BER) creates DNA breaks that permit recombination between distal switch regions. Ataxia telangiectasia mutated (ATM)-dependent phosphorylation of AID at serine 38 (pS38-AID) promotes its interaction with apurinic/apyrimidinic endonuclease 1 (APE1), a BER protein, suggesting that ATM regulates CSR through BER.
View Article and Find Full Text PDFCell Mol Life Sci
June 2022
Sorbonne Université, UPMC Univ Paris 06, INSERM, UMRS 938, SIRIC CURAMUS, Equipe Instabilité Des Microsatellites Et Cancer, Equipe Labellisée Par La Ligue Contre Le Cancer, Centre de Recherche Saint Antoine, 75012, Paris, France.
Heat shock proteins (HSPs) play oncogenic roles in human tumours. We reported a somatic inactivating mutation of HSP110 (HSP110DE9) in mismatch repair-deficient (dMMR) cancers displaying microsatellite instability (MSI) but did not assess its impact. We evaluated the impact of the Hsp110DE9 mutation on tumour development and the chemotherapy response in a dMMR knock-in mouse model (Hsp110DE9Msh2 mice).
View Article and Find Full Text PDFGut Microbes
May 2022
Division of Tumor Biology and Immunology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
The gut microbiota strongly impacts the development of sporadic colorectal cancer (CRC), but it is largely unknown how the microbiota affects the pathogenesis of mismatch-repair-deficient CRC in the context of Lynch syndrome. In a mouse model for Lynch syndrome, we found a nearly complete loss of intestinal tumor development when animals were transferred from a conventional "open" animal facility to specific-pathogen-free (SPF) conditions. Using 16S sequencing we detected large changes in microbiota composition between the two facilities.
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