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GLUT4 promoter activity is regulated by hormonal, metabolic, and tissue-specific controls. This complicates the study of GLUT4 gene transcription, as no cell culture model adequately recapitulates these extracellular regulators. While investigating cultured primary adipocytes as a model system for GLUT4 transcription, we observed that GLUT4 mRNA was specifically and rapidly downregulated upon tissue dispersal. Downregulation of GLUT4 mRNA was mediated in part by loss of regulatory control by the trans-acting factors that control GLUT4 transcriptional activity [the myocyte enhancer factor 2 (MEF2) transcription factor family and the GLUT4 enhancer factor] and their cognate DNA binding sites in transgenic mice. The differences in GLUT4 transcription when whole adipose tissue and cell culture model systems are compared can be correlated to a posttranslational phosphorylation of the transcription factor MEF2A. The difference in the MEF2A phosphorylation state in whole tissue vs. isolated cells may provide a further basis for the development of an in vitro system that could recapitulate fully regulated GLUT4 promoter activity. Development of an in vitro system to reconstitute GLUT4 transcriptional regulation will further efforts to discern the molecular mechanisms that underlie GLUT4 expression. glucose transporter-4 transcription; myocyte enhancer factor 2

As the primary glucose transporter in skeletal muscle, GLUT4 is an important factor in the regulation of blood glucose. We previously reported that stimulation of AMP-activated protein kinase (AMPK) with 5-aminoimidazole-4-carboxamide-1-[beta]-D-ribofuranoside (AICAR) increased GLUT4 expression in muscle. GLUT4 enhancer factor (GEF) and myocyte enhancer factor 2 (MEF2) have been shown to be important for normal GLUT4 expression because deletion or truncation of the consensus sequences on the promoter causes depressed GLUT4 mRNA expression. This led to the current study to investigate possible roles for GEF and MEF2 in mediating the activation of GLUT4 gene transcription in response to AMPK. Here we show that, although AMPK does not appear to phosphorylate MEF2A, AMPK directly phosphorylates the GEF protein in vitro. MEF2 and GEF are activated in response to AMPK as we observed translocation of both to the nucleus after AICAR treatment. Nuclear MEF2 protein content was increased after 2 h, and GEF protein was increased in the nucleus 1 and 2 h post-AICAR treatment. Last, GEF and MEF2 increase in binding to the GLUT4 promoter within 2 h after AICAR treatment. Thus we conclude that GEF and MEF2 mediate the AMPK-induced increase in transcription of skeletal muscle GLUT4. AMPK can phosphorylate GEF and in response to AICAR, GEF, and MEF2 translocate to the nucleus and have increased binding to the GLUT4 promoter. 5-aminoimidazole-4-carboxamide-1-[beta]-D-ribofuranoside; glutathione S-transferase; glucose transporter 4

Research has been conducted on the histidine-containing phosphotransfer (HPt) domain. The effect of the HPt YPD1 protein on the phosphostability of the response regulator domains has been investigated and the results are discussed.

Byline: Daryl Van Moorsel, J.A.L. Cranfield, David Sparling Advancement in biotechnology requires continued innovative activity by firms. To grow, biotechnology firms must understand the factors affecting their innovative activity. Such understanding also informs policy makers, and supports the development of policies promoting one's biotechnology sector. This study explores factors, which determine innovative activity within the Canadian biotechnology industry. Innovative activity is measured as the natural log of the number of products/processes a firm has at different stages of the innovation spectrum. A model is developed to regress this measure on several determinants of innovation. Significant drivers of innovation include: collaborative arrangements, transfer of intellectual property, firm size and age, whether the firm was in the agricultural or human health biotechnology sectors and whether the firm focused on development or commercialisation. Generally speaking, these factors all contributed to firms having more products/processes either under development, undergoing clinical trials or regulatory approval, or on the market.