Define role of Lipids in Controlling Gene Expression?
In the lipogenic pathway, the genes that encode the enzymes of the fatty acid synthase complex are co-ordinately expressed. Whether increased or decreased, all enzymes are synthesized to the same extent so that the pathway can function efficiently.Studies of the transcription and translation of all of the constituent components of this multifunctional complex have revealed that the fatty acid synthase is represented by a single gene that encodes seven gene products, the seven enzyme components of the fatty acid synthase complex. This enzyme complex is regulated by nutrients at the levels of both transcription and translation. Arachidonic acid, a fatly acid with 20 carbons and four double bonds, suppresses gene transcription. It is likely that the mechanism is one that involves a fatty acid binding protein that in turn binds to DNA as trans-acting element.
S14, a protein that seems to be important in the regulation of mRNA transcription of not only fatty acid synthase but also a number of carbohydrate metabolic enzymes, also, is suppressed by long-chain polyunsaturated fatty acids. The S14 gene has a Carbohydrate- responsive element as well. When diets rich in sugar are consumed, S14 mRNA increases, as do the mRNAs for glucokinase, glucose-6-phosphate dehydrogenase; 6-phosphogluconate dehydrogenase, and malice enzyme. In each of these instances, nutrients (glucose, fatty acids) are actively involved as parts of transcription regulatory elements.