Research objectives and content The goal of the proposed research project is to elucidate, in mammals, the mechanisms which are involved in the transcriptional regulation of genes by glucose with special focus on the role of AMP- activated protein kinase (AMPK). AMPK is the mammalian homologue of the SNF1 system in yeast where SNF1 is required for glucose repression and activation of glucose-regulated genes. Since glucose is known to inactivate the kinase activity of SNF1 in yeast, it is proposed that the transcriptional action of glucose in mammals can require AMPK inactivation. We will determine, if and in which way, AMPK activity is sensitive to glucose and if any phosphorylation-dephosphorylation events are implicated. Preliminary experiments in the laboratory of Axel Kahn propose indeed a role of AMPK in the transcriptional machinery. As well as the yeast SNF1 complex, AMPK consists of three subunits. Expression of these wildtype and/or mutated subunits ex vivo (in hepatoma cells, and primary hepatocytes) and in vivo (in transgenic mice) will be used to determine their ability to modulate glucose responsiveness and to clarify if glucose regulates the interaction between the subunits as described for the SNF1 system. Furthermore we will create AMPK-/- knock out mice to firmly establish the role of AMPK in vivo.
Training content (objective, benefit and expected impact)
Gene regulation by nutrients is one important mechanism in mammals to adapt to their nutritional environment. The proposed project is in the process of providing answers to a key question in the field of transcriptional control by nutrients: how glucose, a major regulator of gene expression active in all forms of life, regulates transcription. The analysis of mammalian AMPK will contribute to elucidate basic mechanisms of glucose signaling pathway and will have an impact for the understanding of metabolic diseases.
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