Gene regulation and molecular toxicology

The study of gene expression has become a cornerstone of molecular toxicology and toxicogenomics. Front a toxicological standpoint, constitutive expression levels of a gene could be just as important in determining the outcome of toxicity as the inducible expression. There are six distinct steps at which gene expression can be controlled; these are transcription, RNA processing, RNA transport, translation, mRNA degradation, and control of protein activity. While this overall paradigm of gene regulation is still valid, the complexity of genetic regulation begins mostly at the level of transcription and certain post-transcriptional events. A thorough understanding of the complexity and fluidity of gene and genome structure and their regulation is an integral part in the theory and practice of molecular toxicology and toxicogenomics. The present article is an attempt to briefly summarize our understanding of gene regulation beginning from the cistron concept. Relevance of molecular toxicology to gene regulatory mechanisms has been emphasized with examples wherever appropriate.