Triptolide has long been used as an ingredient in Chinese herbal therapy. The source of the chemical, a plant commonly referred to as lei gong teng or “thunder god vine,” has proven to work both as an anti-inflammatory and as an anti-tumor drug. Precisely how triptolide functions, was unknown, but a recent article in Nature now illuminates its mechanism of action.
Triptolide irreversibly binds to the XPB proteinOne of the four basic types of biomolecule. Proteins are polymers made up of strings of amino acids. Proteins serve many functions in organisms including transport of molecules, structure, cell adhesion and as signaling molecules such as hormones. Many transcription factors, including p53 and Rb are proteins., a subunit of the transcription factorA molecule, usually a protein, that binds to DNA at the start of a gene, enabling that gene to be transcribed (copied) to form an RNA molecule. Transcription factors bind to specific parts of genes called promoters, so called because they promote transcription. Transcription factor binding to gene promoters is critical for regulation of the process. Since transcription factors ultimately control what genes are turned 'on' at any given time, they are essential for the proper functioning of the cell. A wide range of transcription factors are known to be associated with cancer. Changes, or mutations, in these genes leads to a deregulation of the whole process. Some key transcription factors are the p53 and Rb proteins. TFIIH. THe XPB protein is involved in unwinding DNAAbbreviation for deoxyribonucleic acid. Composed of very long strings of nucleotides, which are abbreviated as A, C, G and T. DNA is the storage form of our genetic material. All of the instructions for the production of proteins are encoded in our DNA. . Binding of triptolide to XPB inhibits transcription (the copying of DNA into RNAAlso: ribonucleic acid. RNA is a polymer comprised of the nucleotides A, C, G and U. RNA is the working form of our genetic information. RNA is produced via the process of transcription. Some RNA is used to help build ribosomes (rRNA) and some (mRNA) are used to guide the formation of proteins. Other forms of RNA are used to perform specialized functions in the nucleus.), and may also prevent a type of DNA repair (nucleotideA monomer building block of the nucleic acids DNA and RNA. There are approximately 3 billion nucleotides in the entire human genome. Each chromosome contains about 50-250 million nucleotides. Four nucleotides are used to form DNA abbreviated as A, C, G and T. RNA contains four nucleotides as well, but uses U instead of T, so RNA contains A, C, G and U. Some chemotherapy agents, like 5-Fluorouracil ( 5-FU) and ARA-C are chemically very similar to one of the nucleotides and work by interfering with DNA function. excision repair). The latter would trigger an accumulation of genetic mistakes, which would signal the body to target affected cells for elimination. Furthermore, triptolide appears to enhance the anti-cancer function of DNA-damaging drugs such as cisplatin and may be useful as a new type of cancer drug.
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