For several years, scientists have tried to find genetic links to nicotine dependence. Although studies have found many genes to be associated with tobacco smoking, only small handful are actually considered causative, and these genes are difficult to identify. As denoted by the central dogma of biology, DNA encodes RNA, and RNA codes for proteins; however, it is now widely know that some types of RNA have alternate roles. One type of non-protein-coding RNA is microRNA. Named for their relatively small size, microRNA influence the extent to which genes are expressed, which in biological terms, is the rate of conversion of specific DNA to RNA.To date, microRNA has not been shown to play a significant role in psychiatric disorders; however, a recent study published in Biological Psychiatry has made the discovery that variations in the expression of the dopamine D1 receptor gene may have a causal link to the likelihood of nicotine addiction. In a previous study, researchers at the University of Virginia, Huang and Li showed the dopamine D1 receptor gene is causatively linked with nicotine dependence (the dopamine D1 receptor is one of the major receptors in the brain that mediate the action of dopamine neurotransmitters). Huang and Li found that the two alleles of the dopamine D1 receptor gene can be expressed to different degrees. Their current study demonstrates that the variations in expression are regulated by microRNA miR-504, thus it can be said that microRNA directly influences the expression of genetic variations that predispose an individual to developing an addiction to nicotine. This finding is of interest to the scientific community because it shows how certain genes can vary their degree of expression by using a “micro switch”, that is, microRNA.
Original Article: http://www.sciencedaily.com/releases/2009/04/090423082758.htm
Posted by 42014007
Posted by 42014007
