Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.4.4 (adenosine deaminase)
 5,136 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We describe a cytotoxic T lymphocyte-mediated cytotoxicity assay in which the release of a cytoplasmic enzyme, adenosine deaminase (ADA), instead of the widely used radioactive chromium is a measure of target lysis. In this enzyme-release assay the target is a mastocytoma P815-derived cell line, noted P815 ADA++, isolated by applying a selection procedure devised to specifically amplify the ADA gene. Gene amplification in P815 ADA++ was indeed demonstrated. Routine measurement of ADA activity from numerous supernatants is performed using a specific and sensitive colorimetric assay. The use of 96-well microtiter plates as well as of an automatic Multiscan spectrophotometer makes this measurement rapid and convenient. We show that this ADA-release assay is significantly more sensitive than the classical chromium-release test because of its consistently lower (5 to 10-fold) spontaneous release in 4 h, short-term cytotoxicity experiments. We also found that it is especially suited for the rapid detection, by visual screening, of rare, active killer clones among large, heterogeneous cytotoxic T lymphocyte populations. The assay could easily be adapted to other tumor targets (EL4, YAC-1, K562) of common use in studies involving immune lysis; indeed, the procedure of amplifying the ADA gene used in the isolation of the P815 ADA++ hyperactive line may be generally applied to these targets.
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PMID:Use of a P815-derived line with an amplified adenosine deaminase gene: an improved target for cellular cytotoxicity. 393 81

Hexavalent chromium [Cr(VI)] compounds that are generated during industrial processes are widely recognized as highly toxic and carcinogenic. It has been reported that exposure to Cr(VI) can produce some chromium intermediates and reactive oxygen species (ROS), which causes DNA damages, genetic instability, and eventually leads to the elevated risk of various diseases including cancers. In recent years, it has been proposed that epigenetic-based mechanisms may involve in the toxic heavy metals-induced cytotoxicity and mutagenicity besides the genetic-based mechanisms. However, whether Cr(VI) could impose its cytotoxic effect through dysregulating the RNA epigenetic modifications remains poorly defined. We systematically investigated the effects of Cr(VI) exposure on 14 kinds of modifications in mRNA of HEK293T cells. We found that Cr(VI) exposure can induce an obvious decrease of inosine in mRNA. In addition, we observed that the expression level of the adenosine deaminase acting on RNA (ADAR1) was significantly decreased upon Cr(VI) exposure, which could be responsible for the induced decrease of inosine in mRNA by Cr(VI) exposure. Together, we demonstrated that Cr(VI) could interrupt A-to-I RNA editing in mRNA, which may eventually lead to the cytotoxicity and mutagenicity.
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PMID:Analysis of the Effects of Cr(VI) Exposure on mRNA Modifications. 3143 69