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Hanen Ouadani, Imen Ben-Mustapha, Meriem Ben-Ali, Beya Larguèche, Tihana Jovanic, Sylvie Garcia, Benoit Arcangioli, Houda Elloumi-Zghal, Dahmani Fathallah, Mongia Hachicha, Hatem Masmoudi, François Rougeon, Mohamed-Ridha Barbouche
Activation induced cytidine deaminase (AID) is an essential enzyme for class switch recombination (CSR) and somatic hypermutation (SHM) during secondary immune response. Mutations in the AICDA gene are responsible for Hyper IgM 2 syndrome where both CSR and SHM or only CSR are affected. Indeed, triggering either of the two mechanisms requires the DNA deamination activity of AID. Besides, different domains of AID may be differentially involved in CSR and SHM through their interaction with specific cofactors...
October 4, 2016: Molecular Immunology
Tineke Cantaert, Jean-Nicolas Schickel, Jason M Bannock, Yen-Shing Ng, Christopher Massad, Fabien R Delmotte, Natsuko Yamakawa, Salome Glauzy, Nicolas Chamberlain, Tuure Kinnunen, Laurence Menard, Aubert Lavoie, Jolan E Walter, Luigi D Notarangelo, Julie Bruneau, Waleed Al-Herz, Sara Sebnem Kilic, Hans D Ochs, Charlotte Cunningham-Rundles, Mirjam van der Burg, Taco W Kuijpers, Sven Kracker, Hideo Kaneko, Yujin Sekinaka, Shigeaki Nonoyama, Anne Durandy, Eric Meffre
Patients with mutations in AICDA, which encodes activation-induced cytidine deaminase (AID), display an impaired peripheral B cell tolerance. AID mediates class-switch recombination (CSR) and somatic hypermutation (SHM) in B cells, but the mechanism by which AID prevents the accumulation of autoreactive B cells in blood is unclear. Here, we analyzed B cell tolerance in AID-deficient patients, patients with autosomal dominant AID mutations (AD-AID), asymptomatic AICDA heterozygotes (AID+/-), and patients with uracil N-glycosylase (UNG) deficiency, which impairs CSR but not SHM...
October 4, 2016: Journal of Clinical Investigation
Jin Soo Choi, Ryeo-Ok Kim, Seokjoo Yoon, Woo-Keun Kim
Zinc oxide nanoparticles (ZnO NPs) are being utilized in an increasing number of fields and commercial applications. While their general toxicity and associated oxidative stress have been extensively studied, the toxicological pathways that they induce in developmental stages are still largely unknown. In this study, the developmental toxicity of ZnO NPs to embryonic/larval zebrafish was investigated. The transcriptional expression profiles induced by ZnO NPs were also investigated to ascertain novel genomic responses related to their specific toxicity pathway...
2016: PloS One
Zachary R Hunter, Lian Xu, Guang Yang, Nicholas Tsakmaklis, Josephine M Vos, Xia Liu, Jie Chen, Robert J Manning, Jiaji G Chen, Philip Brodsky, Christopher J Patterson, Joshua Gustine, Toni Dubeau, Jorge J Castillo, Kenneth C Anderson, Nikhil M Munshi, Steven P Treon
Whole-genome sequencing has identified highly prevalent somatic mutations including MYD88, CXCR4, and ARID1A in Waldenström macroglobulinemia (WM). The impact of these and other somatic mutations on transcriptional regulation in WM remains to be clarified. We performed next-generation transcriptional profiling in 57 WM patients and compared findings to healthy donor B cells. Compared with healthy donors, WM patient samples showed greatly enhanced expression of the VDJ recombination genes DNTT, RAG1, and RAG2, but not AICDA Genes related to CXCR4 signaling were also upregulated and included CXCR4, CXCL12, and VCAM1 regardless of CXCR4 mutation status, indicating a potential role for CXCR4 signaling in all WM patients...
August 11, 2016: Blood
Kim Steve Bergkvist, Martin Agge Nørgaard, Martin Bøgsted, Alexander Schmitz, Mette Nyegaard, Michael Gaihede, John Bæch, Marie-Louise Grønholdt, Frank Svendsen Jensen, Preben Johansen, Thomas Urup, Tarec C El-Galaly, Jakob Madsen, Julie Støve Bødker, Karen Dybkær, Hans Erik Johnsen
The rare memory B cells in thymus (Thy) are considered the cells of origin for primary mediastinal large B-cell lymphoma. The objectives of the present study were to characterize the normal memory B-cell compartment in Thy and to support its association with primary mediastinal B-cell lymphoma. Seven paired human tissue samples from Thy and sternum bone marrow (BM) were harvested during cardiac surgery. B-cell subsets were phenotyped by Euroflow standard and fluorescence-activated cell sorting for microarray analysis on the Human Exon 1...
October 2016: Experimental Hematology
Miriam Wöhner, Hiromi Tagoh, Ivan Bilic, Markus Jaritz, Daniela Kostanova Poliakova, Maria Fischer, Meinrad Busslinger
E2A is an essential regulator of early B cell development. Here, we have demonstrated that E2A together with E2-2 controlled germinal center (GC) B cell and plasma cell development. As shown by the identification of regulated E2A,E2-2 target genes in activated B cells, these E-proteins directly activated genes with important functions in GC B cells and plasma cells by inducing and maintaining DNase I hypersensitive sites. Through binding to multiple enhancers in the Igh 3' regulatory region and Aicda locus, E-proteins regulated class switch recombination by inducing both Igh germline transcription and AID expression...
June 27, 2016: Journal of Experimental Medicine
Yuji Eso, Atsushi Takai, Tomonori Matsumoto, Tadashi Inuzuka, Takahiro Horie, Koh Ono, Shinji Uemoto, Kyeryoung Lee, Winfried Edelmann, Tsutomu Chiba, Hiroyuki Marusawa
Inflammation predisposes to tumorigenesis in various organs by potentiating a susceptibility to genetic aberrations. The mechanism underlying the enhanced genetic instability through chronic inflammation, however, is not clear. Here, we demonstrated that TNFα stimulation induced transcriptional downregulation of MSH2, a member of the mismatch repair family, via NF-κB-dependent miR-21 expression in hepatocytes. Liver cancers developed in ALB-MSH2(-) (/) (-)AID(+), ALB-MSH2(-) (/) (-), and ALB-AID(+) mice, in which MSH2 is deficient and/or activation-induced cytidine deaminase (AICDA) is expressed in cells with albumin-producing hepatocytes...
August 1, 2016: Cancer Research
Ferdinand von Meyenn, Mario Iurlaro, Ehsan Habibi, Ning Qing Liu, Ali Salehzadeh-Yazdi, Fátima Santos, Edoardo Petrini, Inês Milagre, Miao Yu, Zhenqing Xie, Leonie I Kroeze, Tatyana B Nesterova, Joop H Jansen, Hehuang Xie, Chuan He, Wolf Reik, Hendrik G Stunnenberg
Global demethylation is part of a conserved program of epigenetic reprogramming to naive pluripotency. The transition from primed hypermethylated embryonic stem cells (ESCs) to naive hypomethylated ones (serum-to-2i) is a valuable model system for epigenetic reprogramming. We present a mathematical model, which accurately predicts global DNA demethylation kinetics. Experimentally, we show that the main drivers of global demethylation are neither active mechanisms (Aicda, Tdg, and Tet1-3) nor the reduction of de novo methylation...
June 16, 2016: Molecular Cell
Ying-Yu Wu, Ramesh Kumar, Ryuji Iida, Harini Bagavant, Marta E Alarcón-Riquelme
The purpose of our study was to investigate the effects of the adaptor Bank1 in TLR7 signaling using the B6.Sle1.yaa mouse, a lupus model that develops disease through exacerbated TLR7 expression. Crosses of B6.Sle1.yaa with Bank1-/- mice maintained several B and myeloid cell phenotypes close to normal wild-type levels. Most striking was the reduction in total serum IgG antibodies, but not of IgM, and reduced serum levels of autoantibodies, IL-6, and BAFF. Bank1 deficiency did modify numbers of MZ B cells and total B cell numbers, as well as expression of CXCR4 by follicular helper T cells...
2016: PloS One
Jens S Kalchschmidt, Rachael Bashford-Rogers, Kostas Paschos, Adam C T Gillman, Christine T Styles, Paul Kellam, Martin J Allday
Activation-induced cytidine deaminase (AID), the enzyme responsible for induction of sequence variation in immunoglobulins (Igs) during the process of somatic hypermutation (SHM) and also Ig class switching, can have a potent mutator phenotype in the development of lymphoma. Using various Epstein-Barr virus (EBV) recombinants, we provide definitive evidence that the viral nuclear protein EBNA3C is essential in EBV-infected primary B cells for the induction of AID mRNA and protein. Using lymphoblastoid cell lines (LCLs) established with EBV recombinants conditional for EBNA3C function, this was confirmed, and it was shown that transactivation of the AID gene (AICDA) is associated with EBNA3C binding to highly conserved regulatory elements located proximal to and upstream of the AICDA transcription start site...
May 30, 2016: Journal of Experimental Medicine
Luca Trotta, Timo Hautala, Sari Hämäläinen, Jaana Syrjänen, Hanna Viskari, Henrikki Almusa, Maija Lepisto, Meri Kaustio, Kimmo Porkka, Aarno Palotie, Mikko Seppänen, Janna Saarela
Antibody class-switch recombination and somatic hypermutation critically depend on the function of activation-induced cytidine deaminase (AID). Rare variants in its gene AICDA have been reported to cause autosomal recessive AID deficiency (autosomal recessive hyper-IgM syndrome type 2 (HIGM2)). Exome sequencing of a multicase Finnish family with an HIGM2 phenotype identified a rare, homozygous, variant (c.416T>C, p.(Met139Thr)) in the AICDA gene, found to be significantly enriched in the Finnish population compared with other populations of European origin (38...
October 2016: European Journal of Human Genetics: EJHG
Taichiro Nonaka, Yoshinobu Toda, Hiroshi Hiai, Munehiro Uemura, Motonobu Nakamura, Norio Yamamoto, Ryo Asato, Yukari Hattori, Kazuhisa Bessho, Nagahiro Minato, Kazuo Kinoshita
Most skin cancers develop as the result of UV light-induced DNA damage; however, a substantial number of cases appear to occur independently of UV damage. A causal link between UV-independent skin cancers and chronic inflammation has been suspected, although the precise mechanism underlying this association is unclear. Here, we have proposed that activation-induced cytidine deaminase (AID, encoded by AICDA) links chronic inflammation and skin cancer. We demonstrated that Tg mice expressing AID in the skin spontaneously developed skin squamous cell carcinoma with Hras and Trp53 mutations...
April 1, 2016: Journal of Clinical Investigation
Alexander D Gitlin, Lotta von Boehmer, Anna Gazumyan, Ziv Shulman, Thiago Y Oliveira, Michel C Nussenzweig
Somatic hypermutation (SHM) and class-switch recombination (CSR) increase the affinity and diversify the effector functions of antibodies during immune responses. Although SHM and CSR are fundamentally different, their independent roles in regulating B cell fate have been difficult to uncouple because a single enzyme, activation-induced cytidine deaminase (encoded by Aicda), initiates both reactions. Here, we used a combination of Aicda and antibody mutant alleles that separate the effects of CSR and SHM on polyclonal immune responses...
April 19, 2016: Immunity
Martina Minnich, Hiromi Tagoh, Peter Bönelt, Elin Axelsson, Maria Fischer, Beatriz Cebolla, Alexander Tarakhovsky, Stephen L Nutt, Markus Jaritz, Meinrad Busslinger
The transcription factor Blimp-1 is necessary for the generation of plasma cells. Here we studied its functions in plasmablast differentiation by identifying regulated Blimp-1 target genes. Blimp-1 promoted the migration and adhesion of plasmablasts. It directly repressed genes encoding several transcription factors and Aicda (which encodes the cytidine deaminase AID) and thus silenced B cell-specific gene expression, antigen presentation and class-switch recombination in plasmablasts. It directly activated genes, which led to increased expression of the plasma cell regulator IRF4 and proteins involved in immunoglobulin secretion...
March 2016: Nature Immunology
Hanen Ouadani, Imen Ben-Mustapha, Meriem Ben-ali, Leila Ben-khemis, Beya Larguèche, Raoudha Boussoffara, Sonia Maalej, Ilhem Fetni, Saida Hassayoun, Abdelmajid Mahfoudh, Fethi Mellouli, Sadok Yalaoui, Hatem Masmoudi, Mohamed Bejaoui, Mohamed-Ridha Barbouche
Immunoglobulin class switch recombination deficiencies (Ig-CSR-D) are characterized by normal or elevated serum IgM level and absence of IgG, IgA, and IgE. Most reported cases are due to X-linked CD40L deficiency. Activation-induced cytidine deaminase deficiency is the most frequent autosomal recessive form, whereas CD40 deficiency is more rare. Herein, we present the first North African study on hyper IgM (HIGM) syndrome including 16 Tunisian patients. Phenotypic and genetic studies allowed us to determine their molecular basis...
January 2016: Immunogenetics
Nancy J Olsen, Dima A Decker, Paul Higgins, Patrice M Becker, Carl A McAloose, Ann L Benko, William J Kovacs
INTRODUCTION: Both clinical experience and experimental evidence have suggested that Adrenocorticotropic hormone (ACTH) might directly exert immunomodulatory effects not dependent on adrenal steroidogenesis. METHODS: The direct effects of H.P. Acthar Gel (Acthar), a repository preparation containing a porcine ACTH analogue, on human B lymphocyte function were studied in vitro using peripheral blood B cells isolated using anti-CD19 coated magnetic beads and activated by interleukin 4 (IL-4) and CD40 ligand (CD40L)...
2015: Arthritis Research & Therapy
Sophie Jung, Jean-Nicolas Schickel, Aurélie Kern, Anne-Marie Knapp, Pierre Eftekhari, Sylvia Da Silva, Benoît Jaulhac, Robert Brink, Pauline Soulas-Sprauel, Jean-Louis Pasquali, Thierry Martin, Anne-Sophie Korganow
The links between infections and the development of B-cell-mediated autoimmune diseases are still unclear. In particular, it has been suggested that infection-induced stimulation of innate immune sensors can engage low affinity autoreactive B lymphocytes to mature and produce mutated IgG pathogenic autoantibodies. To test this hypothesis, we established a new knock-in mouse model in which autoreactive B cells could be committed to an affinity maturation process. We show that a chronic bacterial infection allows the activation of such B cells and the production of nonmutated IgM autoantibodies...
January 2016: European Journal of Immunology
Pilar M Dominguez, Matt Teater, Nyasha Chambwe, Matthias Kormaksson, David Redmond, Jennifer Ishii, Bao Vuong, Jayanta Chaudhuri, Ari Melnick, Aparna Vasanthakumar, Lucy A Godley, F Nina Papavasiliou, Olivier Elemento, Rita Shaknovich
Changes in DNA methylation are required for the formation of germinal centers (GCs), but the mechanisms of such changes are poorly understood. Activation-induced cytidine deaminase (AID) has been recently implicated in DNA demethylation through its deaminase activity coupled with DNA repair. We investigated the epigenetic function of AID in vivo in germinal center B cells (GCBs) isolated from wild-type (WT) and AID-deficient (Aicda(-/-)) mice. We determined that the transit of B cells through the GC is associated with marked locus-specific loss of methylation and increased methylation diversity, both of which are lost in Aicda(-/-) animals...
September 29, 2015: Cell Reports
Luca Tacchi, Erin T Larragoite, Pilar Muñoz, Chris T Amemiya, Irene Salinas
One of the most remarkable innovations of the vertebrate adaptive immune system is the progressive organization of the lymphoid tissues that leads to increased efficiency of immune surveillance and cell interactions. The mucosal immune system of endotherms has evolved organized secondary mucosal lymphoid tissues (O-MALT) such as Peyer's patches, tonsils, and adenoids. Primitive semi-organized lymphoid nodules or aggregates (LAs) were found in the mucosa of anuran amphibians, suggesting that O-MALT evolved from amphibian LAs ∼250 million years ago...
September 21, 2015: Current Biology: CB
Jianmiao Wang, Qinghai Li, Jungang Xie, Yongjian Xu
BACKGROUND: It is incompletely understood how cigarette smoke (CS) exposure affects lung mucosal immune responses during viral respiratory infections. B cell activating factor belonging to the tumor necrosis factor family (BAFF) plays an important role in the induction of secretory immunoglobulin A (S-IgA) which is the main effector of the mucosal immune system. We therefore investigated the effects of CS exposure on BAFF expression and S-IgA responses in the lung during influenza virus infection...
2015: Respiratory Research
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