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Activation-induced Cytidine Deaminase (activation-induced + cytidine_deaminase)

Distribution by Scientific Domains

Medical Sciences	60%
Life Sciences	40%

Selected Abstracts

Differential expression of activation-induced cytidine deaminase (AID) in nodular lymphocyte-predominant and classical Hodgkin lymphoma

THE JOURNAL OF PATHOLOGY, Issue 5 2005
Axel Greiner
Abstract Activation-induced cytidine deaminase (AID) is indispensable for class switch recombination and somatic hypermutation of immunoglobulin genes. Expression of AID has been detected in germinal centre centroblasts and in lymphomas derived from germinal centre cells. However, in situ studies of AID expression have until now been hampered by a lack of antibodies suitable for immunohistochemistry. To overcome this problem, an AID-specific monoclonal antibody suitable for immunohistochemical staining of formalin-fixed, paraffin wax-embedded tissue sections has been generated. This antibody was shown to detect AID expression in normal germinal centre B-cells as well as in non-Hodgkin lymphomas with a putative germinal centre origin. Using this antibody, a virtually exclusive cytoplasmic localization of AID in normal and neoplastic B-cells is shown. Employing a combination of immunohistochemistry and AID-specific in situ hybridization, it is demonstrated that AID is consistently expressed in the neoplastic cells of nodular lymphocyte-predominant Hodgkin lymphoma (HLnlp) but only infrequently in classical HL (cHL). This is in keeping with the notion that tumour cells of HLnlp represent transformed germinal centre B-cells showing evidence of somatic hypermutation. AID represents an additional marker useful in the differential diagnosis of HLnlp and cHL. Copyright © 2005 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source]

GANP suppresses DNA recombination, measured by direct-repeat ,-galactosidase gene construct, but does not suppress the type of recombination applying to immunoglobulin genes in mammalian cells

GENES TO CELLS, Issue 10 2007
Mikoto Yoshida
Immunoglobulin V-region somatic hypermutation and C-region class-switch recombination are initiated by activation-induced cytidine deaminase (AID) in B-cells. AID-induced DNA damage at the immunoglobulin S-region is known to be repaired by non-homologous end-joining, but repair mechanisms at the V-region remain to be elucidated. In Saccharomyces cerevisiae, DNA homologous recombination is regulated by the expression of Sac3, involved in actin assembly, cell cycle transition and mRNA metabolism. Here, we demonstrate that the Sac3-homologue GANP suppresses DNA recombination in a direct-repeat ,-galactosidase gene construct in mammalian cells. Homozygous ganp gene knockout is embryonic lethal in mice. Embryonic fibroblasts immortalized from hetero-deficient ganp+/, mice showed more DNA recombination than wild-type. In contrast, over-expression of GANP suppressed either spontaneous DNA recombination or that caused by the introduction of aid cDNA into NIH3T3 cells (susceptible to I-sceI restriction enzyme cleavage but not to RAG-mediated immunoglobulin gene recombination). GANP suppresses the DNA recombination not only on the extrachromosomal DNA construct but also on the integrated DNA. The Sac3-homology portion is necessary for the suppressive activity, but the truncated carboxyl terminal MCM3-binding/acetylating region adversely augmented DNA recombination, acting as a dominant negative form. Expression of full-length GANP is critical for suppression of DNA hyper-recombination in mammalian cells. [source]

Modulation of Activation-Induced Cytidine Deaminase by Curcumin in Helicobacter pylori -Infected Gastric Epithelial Cells

HELICOBACTER, Issue 6 2009
Syed Faisal Haider Zaidi
Abstract Background:, Anomalous expression of activation-induced cytidine deaminase (AID) in Helicobacter pylori -infected gastric epithelial cells has been postulated as one of the key mechanisms in the development of gastric cancer. AID is overexpressed in the cells through nuclear factor (NF)-,B activation by H. pylori and hence, inhibition of NF-,B pathway can downregulate the expression of AID. Curcumin, a spice-derived polyphenol, is known for its anti-inflammatory activity via NF-,B inhibition. Therefore, it was hypothesized that curcumin might suppress AID overexpression via NF-,B inhibitory activity in H. pylori -infected gastric epithelial cells. Materials and Methods:, MKN-28 or MKN-45 cells and H. pylori strain 193C isolated from gastric cancer patient were used for co-culture experiments. Cells were pretreated with or without nonbactericidal concentrations of curcumin. Apoptosis was determined by DNA fragmentation assay. Enzyme-linked immunosorbent assay was performed to evaluate the anti-adhesion activity of curcumin. Real-time polymerase chain reaction was employed to evaluate the expression of AID mRNA. Immunoblot assay was performed for the analysis of AID, NF-,B, inhibitors of NF-,B (I,B), and I,B kinase (IKK) complex regulation with or without curcumin. Results:, The adhesion of H. pylori to gastric epithelial cells was not inhibited by curcumin pretreatment at nonbactericidal concentrations (,10 ,mol/L). Pretreatment with nonbactericidal concentration of curcumin downregulated the expression of AID induced by H. pylori. Similarly, NF-,B activation inhibitor (SN-50) and proteasome inhibitor (MG-132) also downregulated the mRNA expression of AID. Moreover, curcumin (,10 ,mol/L) has suppressed H. pylori -induced NF-,B activation via inhibition of IKK activation and I,B degradation. Conclusion:, Nonbactericidal concentrations of curcumin downregulated H. pylori -induced AID expression in gastric epithelial cells, probably via the inhibition of NF-,B pathway. Hence, curcumin can be considered as a potential chemopreventive candidate against H. pylori -related gastric carcinogenesis. [source]

Differential expression of activation-induced cytidine deaminase (AID) in nodular lymphocyte-predominant and classical Hodgkin lymphoma

AID in reprogramming: Quick and efficient

BIOESSAYS, Issue 5 2010
Identification of a key enzyme called AID, its activity in DNA demethylation, may help to overcome a pivotal epigenetic barrier in reprogramming somatic cells toward pluripotency
Abstract Current methods of reprogramming differentiated cells into induced pluripotent stem cells remain slow and inefficient. In a recent report published online in Nature, Bhutani et al.1 developed a cell fusion strategy, achieving quick and efficient reprogramming toward pluripotency. Using this assay, they identified an immune system protein called activation-induced cytidine deaminase, or AID, which unexpectedly is actually able to "aid" in reprogramming due to its involvement in DNA demethylation that is required for induction of the two key pluripotency genes, Oct4 and Nanog. More recently, Popp et al.2 also reported online in Nature that AID is important for complete cell reprogramming in mammals. Together, these findings provide new insights into how cells are reprogrammed, identify the specific role of AID in cell fate reversal, and advance the field of regenerative medicine. [source]