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Biochemical Society Transactions (2002) Volume 30, Part 6 15 Transgenic wheat lines mimicking metabolic responses to the Greenhouse effect. T. Beacham, D. Edlin, P. Kille, and J.L. Harwood School of Biosciences, Cardiff University, PO Box 911, Card# CFlO 3US, Wales, U.K. Current predictions suggest C 0 2 concentrations will approximately double to 650 p . p m and that temperature will rise by an average of 4 "C by the middle of the century. These Greenhouse conditions significantly affect wheat lipid metabolism. It is proposed that these metabolic changes are due to altered activity of two key enzymes: glycerol 3-phosphate acyltransferase and acyl-ACP thioesterase. The substrate specificities and relative activities of these two enzyme systems determines the fate of newly formed fatty acids in the chloroplast. Transgenic lines were created containing either a Pisum sativum (pea) glycerol %phosphate acyltransferase gene, o r an Arabidopsis thaliana acyl-ACP thioesterase gene, singularly o r in combination. Plants transformed with the pea acyltransferase contained more mitochondria and chloroplasts than non-transformed wheat and also exhibited significantly larger chloroplasts. Preliminary results indicate a significant alteration in growth rate in lines transformed with pea glycerol 3-phosphate acyltransferase o n its own o r in combination with the Arabidopsis thaliana acyl-ACP thioesterase gene. It is notable that changes in transgenic wheats mimic those seen in plants grown under 'Greenhouse' conditions. 16 Differential effects of n-3 polyunsaturated fatty acids on tendon versus cartilage metabolism S.G. Rees, C.L. Curtis, B. Caterson, J.L. Harwood Connective Tissue Biology Labs, Cardiff University, CFlO 3US. Previous studies have demonstrated that exposure of normal bovine and human osteoarthritic cartilage to n-3 polyunsaturated fatty acids (PUFAs), but not other classes of fatty acids, can modulate the expression and activity of degradative and inflammatory factors that are responsible for cartilage destruction. In these studies, supplementation of cartilage explant cultures with n-3 PUFAs resulted in the dose-dependent reduction in aggrecanase and collagenase proteolytic activity. In addition, the expression of m R N A for the inflammatory mediators cyclooxygenase-2,5-lipoxygenase,5lipoxygenase-activating protein, tumour necrosis factor- (Y and interleukin-la and p was also abolished. The present work examines the effect of n-3 PUFA supplementation o n tendon metabolism. Importantly, within this musculoskeletal tissue, aggrecanases are constitutively active and appear to be involved in normal, everyday turnover of aggrecan, in contrast to articular cartilage. Exposure of bovine tendon explant cultures to either n-3 o r n-6 PUFAs had no effect o n the mRNA expression o r activity of aggrecanases; similarly, expression of the inflammatory mediators was also unaffected. These data demonstrate that the incorporation of n-3 PUFAs have a differential effect o n the regulatory mechanisms which control gene expression within articular cartilage versus tendon. Studies are currently underway to elucidate the precise nature of these control mechanisms. A I2I 17 Effect of AMPK activation o n fatty acid metabolism in epithelia C. Ghioni, K.J. Treharne, A. Mehta, R.E. Olver, S.C. Land, R. Muimo TICH, University of Dundee, Ninewells Hospital, Dundee, DD19SY AMP-activated protein kinase (AMPK) regulates mammalian lipid metabolism by phosphorylating key enzymes including acetyl-CoA carboxylase, 3-hydroxy-3-methylglutaryl-CoA-reductase, lipase and sn-glycerol-3-phosphate acyltransferase. We have shown the presence of AMPK at the apical membrane of airway epithelium and a human bronchial epithelial cell line (HBE). However, the function of AMPK in airway epithelia is not well characterised. Here we show that HBE cells treated with the AMPK activator, 5amino-4-imidazole carboxamine riboside (AICAR, 0.6 mM), display a reduced rate of oxidation (28% less) of 14C-stearic acid (18:0), as measured by I4C-CO2 release. AICAR also induces HBE cells to convert more 14C-stearic acid into monounsaturated fatty acids (oleic acid) (22% vs. 15%) but does not affect radioactivity incorporation into total and individual lipid classes. Following supplementation with 20 p M linoleic acid (18:2w6), AICAR treated HBE cells generate more arachidonic acid, as well as longer chain saturated and monounsaturated fatty acids . Thus AICAR increases the elongation/desaturation of w6 PUFA in HBE cells. O u r results suggest that in airway epithelia the regulation of fatty acid metabolism differs from liver and muscle and that AMPK may play a role in the regulation of desaturases. Financial Support: Wellcome program grant, C F Trust, Anon. Trust. 18 Dipalmitoylphosphatidylcholine regulates PGEZ release in monocytes via effects o n PPAR-gamma. T.T. Lin, A. Thomas, M. Ahluwalia, S.K. Jackson, A. Tonks, A. Price, K.P. Jones, K. Morris. School of Biomedical Sciences, UWIC, Western Avenue Cardiff; CFli 2YB and Departments of Medical Microbiology and Haematology, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN The disaturated species of phosphatidylcholine (1,2Dipalmitoylphosphatidylcholine;DPPC), is a major component of lung surfactant, with a crucial role in preventing lung collapse at the end of expiration. Increasingly, an immunoregulatory role for D P P C has been reported, including its ability to regulate inflammatory cytokine release in monocytes and macrophages. In this study we investigated the ability of D P P C to modulate the production of the regulator of inflammatory cytokine release, prostaglandin E2 (PGE2) from a human monocyte cell line (MonoMac 6 ) . DPPC, at a concentration of 250micrograms/ml, was able to significantly (p<O.Ol) increase the secretion of PGEZ in LPS-stimulated MonoMac 6 cells. When D P P C was substituted by the polyunsaturated species 1 -palmitoyl,2-arachidonoyl PC, no significant increase in PGE2 secretion was observed. Furthermore, incubation of MonoMac 6 cells with D P P C directly down-regulated the expression of the nuclear lipid receptor PPAR-gamma. This study suggests that the anti-inflammatory properties of D P P C may be mediated via its effects o n PPAR-gamma expression and subsequent PGE2 production. 0 2002 Biochemical Society