Overview:
Acetylation of the histone tail causes chromatin to adopt an “open” conformation, allowing trans factors increased accessibility to DNA. The identification of histone acetyltransferases (HATs) and their large multiprotein complexes has yielded important insights into how these enzymes regulate transcription (1,2). HAT complexes interact with sequence-specific activator proteins to target specific genes. In addition to histones, HATs can acetylate non-histone proteins, suggesting multiple roles for these enzymes (3). In contrast, histone deacetylation promotes a “closed” chromatin conformation and typically leads to repression of gene activity (4). Mammalian histone deacetylases can be divided into three classes on the basis of their similarity to various yeast deacetylases (5). Class I (HDACs 1, 2, 3 and 8) proteins are related to the yeast Rpd3-like proteins, those in class II (HDACs 4, 5, 6, 7, 9 and 10) are related to yeast Hda1-like proteins and class III proteins are related to the yeast protein Sir2. Inhibitors of HDAC activity are now being explored as potential therapeutic cancer agents (6,7).
References:
1. Marmorstein, R. et al. (2001) Cell. Mol. Life Sci. 58, 693–703.2. Gregory, P.D. et al. (2001) Exp. Cell Res. 265, 195–202.3. Liu, Y. et al. (2000) Mol. Cell. Biol. 20, 5540–5543.4. Cress, S.D. and Seto, E. (2000) J. Cell. Physiol. 184, 1–16.5. Gray, S.G. and Ekstrom, T.J. (2001) Exp. Cell Res. 262, 75–83.6. Thiagalingam, S. et al. (2003) Ann. N. Y. Acad. Sci. 983, 84–100.7. Viguishin, D.M. and Coombes, R.C. (2004) Curr. Cancer Drug Targets 4, 205–218.
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抗人球蛋白试验，又称Coombs’试验，是诊断自身免疫性溶血性贫血(AIHA)的重要依据。
正常人直接与间接试验均为阴性，Coombs’试验阴性有时并不能排除AIHA
