Molecular Methodologies in Nutrition Research

Abstract

In the early stages of the evolution of life forms, cellular growth and evolutionary success required that the developing organism respond to a myriad of environmental factors. In particular, an organism had to be able to fulfill its nutrient needs as well as to sense periods of nutrient deficiency or excess and then turn on pathways of synthesis or storage. Because of this need to sense changes in nutrient environment, early cell life forms developed switches that regulated the transcription of genes encoding proteins involved in such metabolic functions as sugar synthesis and amino acid transport. This regulation of gene expression and metabolism was, in essence, a primitive hormonal signaling system used for the survival and growth of the organism. As single cell organisms evolved into complex life forms, nutrients continued to act as environmental signals to regulate gene expression and metabolism. These dietary signals and their effects on gene expression could be both beneficial and detrimental in the etiology of such nutritionally related pathophysiologies as diabetes, cancer and heart disease. We are now beginning to understand how nutrients govern gene expression and the abundance of pivotal metabolic and structural proteins. We now know that dietary constituents can govern the expression of proteins at a number of transcriptional and posttranscriptional points. For example, fatty acids, retinoic acid and cholecalciferol have specific nuclear receptors. Following ligand activation, the receptors interact with specific DNA recognition sequences within a particular gene and either up or down regulate the gene’s rate of transcription (Alroy et al. 1995, Mangelsdorf and Evans 1995, Schoonjans et al. 1996). Recent data also suggest that carbo