Regulation of gene expression by nutrients in mammals isan important mechanism allowing them to adapt to the nutritional environment. In-vivo and in-vitro experiments have demonstrated that the transcription of genes coding for lipogenic and glycolytic enzymes in liver andsol;or adipose tissue is upregulated by glucose. In order for glucose to act as a gene inducer, it must be metabolized. Recent evidence suggests that glucose-6-phosphate is the signal metabolite in the liver. DNA glucose response elements have been characterized and they have in common the presence of two sequences 5prime;-CACGTG-3prime; separated by five nucleotides, which bindin vitroa transcription factor of the basic domain, helix-loop-helix, leucine zipper family called USFsol;MLTF. Experiments concerning the potential role of USFsol;MLTF in the glucose response have led to opposite results, suggesting that USFsol;MLTF might not be the only factor involved. Finally, the glucose effect involves a kinasesol;phosphatase system. The kinase could be the AMP-activated protein kinase, the mammalian analogue of a yeast kinase, or SNF1 which is important for the derepression of glucose-inhibited genes.
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