Autoregulation of Protein Synthesis by Translation
In mammalian cells mRNA translation is activated by a variety of stimuli including hormones such as insulin and growth factors. The stimulatory effects of nutrients, in particular, glucose and amino acids, on protein synthesis have recently become a focus of new interest. Acute exposure of pancreatic β-cells to glucose, for example, is known to activate insulin biosynthesis by stimulating translation of pre-existing prepro-insulin mRNA. This regulation at the level of translation rather than at the level of insulin gene transcription ensures a rapid replenishment of stored insulin content after exocytosis. Dietary amino acids have also been shown to stimulate muscle protein synthesis after food intake (1, 2). This anabolic effect may be attributed in part to an increase in amino acid supply to muscle, thereby augmenting substrate availability for peptide synthesis. However, many recent studies suggest that amino acids also function independently as nutritional signaling molecules that regulate mRNA translation. In this chapter, the effects of nutrients, glucose and amino acids, on the regulation of protein synthesis by activating key regulatory translation factors will be discussed primarily focusing on pancreatic β-cells.
KeywordsBasal Amino Acid Insulin Receptor Substrate RINm5F Cell Insulin Gene Expression Stimulate Muscle Protein Synthesis
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