Nucleosome nuc leosome and histone DNA interactions take place to tighten or loosen the chromatin structure, prohibiting or permitting access of the transcriptional machinery, such as RNA polymerase II and regulatory factors, to the DNA sequence. Gene activities Oligomycin A BTB06584? and thus genomic functions can change independent of the DNA sequence. Chromatin structure is altered by covalent modifications to the amino acid residues in the unstructured tails of histones. For ex ample, acetylation of the lysines in H3 and H4 N termini neutralizes the otherwise positively charged histones, weakening the coupling between histones and negatively charged DNA sugar phosphate backbone. The relaxing chromatin is associated with active gene transcription, so is cytosine hypomethylation, a covalent modification to the DNA that is found in association with histone acetyl ation.
An equally important property of histone mo difications and DNA methylation is that modification patterns, once established, propagate through cell divi sions. Different combinations of covalent modifications over the chromatin give rise to different cellular phe notypes. A histone code, supplementary to the DNA sequence, for cellular functions was therefore recently proposed. Traditional Chinese medicine has developed a system of theories and practices since at least 2,000 years ago and remains popular in some Far East Asian areas. In contrast to the reductionist approach of modern western medicine, TCM diagnoses a patient via inspection, listening/smelling, questioning and palpa tion.
Emotional, mental and envir onmental factors are usually also taken into account. Outcomes of the diagnostics are summarized as TCM syndromes which are usually clas sified under the eight outlines yin or yang, internal or ex ternal, cold or hot, deficiency or excess. Yin and yang in TCM refer, respectively, to the materialistic and func tional qualities of the body. External and internal indicate the origin or direction of syndrome development. Cold and hot are manifestations of the syndrome through metabolism and body heat. Deficiency means lack of activ ities, such as immunodeficiency, of the body organ. Two examples of TCM syndromes are Lung Stomach yin deficiency with excessive heat and concurrent yin yang deficiency, both being commonly diagnosed by TCM in type II diabetic patients.
A major feat of TCM is that Chinese herbal formulas that counteract the TCM syndromes have been developed so that once the patients TCM syndrome is identified, the Chinese herbal formula specific GSK-3 to the syndrome is readily prescribed. Due to its diagnostic system, TCM is considered a holistic, per sonalized yet less specific therapy compared to modern western medicine. As histone modifications and cytosine methylation play a role in the activity of genes, aberration in the pattern of modifications to histones and DNA, called epigenome, can lead to disease.