Chemistry and Physics of Lipids 160S (2009) S20–S21 Contents lists available at ScienceDirect Chemistry and Physics of Lipids journal homepage: www.elsevier.com/locate/chemphyslip Abstracts Posters Session 2: Functions of sterol molecular species (PO 4–8) PO 4 SREBP-1c mediated induction of lipid metabolism is crucial for phagocytic differentiation of monocytes Josef Ecker ∗ , Gerhard Liebisch, Marion Englmaier, Margot Grandl, Gerd Schmitz Institute of Clinical Chemistry and Laboratory Medicine, University of Regensburg, Regensburg, Germany Monocytes are precursors of macrophages. Regulation of mono- cyte differentiation is central to the understanding of fundamental macrophage biology and metabolic diseases such as atherosclero- sis. The role of fatty acid metabolism for phagocytic differentiation of monocytes is completely unexplored. Here we demonstrate that M-CSF dependent differentiation of primary human monocytes from healthy volunteers induces SREBP-1c and impairs SREBP-2 transcription including their tar- get genes. Detailed lipid metabolic profiling showed that this transcriptional regulation leads to a dramatically increased fatty acid synthesis, representing the driving force for enhanced phos- phatidylcholine and phosphatidylethanolamine synthesis. During cell differentiation the main lipid class switches from cholesterol in monocytes to phosphatidylcholine in macrophages. Suppression of SREBP-1c activity and inhibition of fatty acid synthesis prevents monocyte differentiation and macrophage function such as phago- cytosis. Therefore activation of SREBP-1c and subsequent induction of fatty acid and glycerophospholipid metabolism are essential for phagocytic differentiation of monocytes. doi:10.1016/j.chemphyslip.2009.06.006 PO 5 Transient overexpression of SREBP-1c represses the human SND1 promoter Sandra Armengol ∗ , Enara Arretxe, Bego˜ na Ochoa, María J. Martínez Department of Physiology, School of Medicine, University of the Basque Country, Barrio Sarriena s/n, Leioa 48940, Spain E-mail address: sandra.armengol@ehu.es (S. Armengol). Sterol regulatory element-binding protein 1c (SREBP-1c) has been established to activate the expression of genes involved in fatty acid metabolism by binding to sterol regulatory elements (SREs) or E-boxes palindromic sequences. Staphylococcal nuclease domain- containing protein 1 (SND1), also called p100 or Tudor-SN, was first identified as a transcription coactivator, but it has been found to be a multifunctional protein with a role in siRNA and mRNA pos- transcriptional processing. The presence of SND1 in non-nuclear regions of lipid secretory tissues and lipid droplets suggests a role for the protein in lipid metabolism. Indeed, the overexpression of the rat homologue protein SND p102 in rat hepatocytes, pro- motes the secretion of phospholipid-rich lipoproteins and it has been recently associated to lipid bodies in hepatocellular esteatosis model. To further understand the SND1 transcriptional regulation, we have isolated a 3492bp promoter sequence (EF690304) show- ing the lack of TATA box and the presence of GC-rich motifs and CCAAT boxes. Bioinformatic analysis has predicted putative bind- ing sites for SREBPs in the (-416, +221) region of the promoter. In this work, 5 ′ deletion fragments were cloned into luciferase reporter gene and their transcriptional activity were determined in human HepG2 cells transiently co-transfected with SREBP-1c expression vector. A reduction in luciferase activity (35–45%) was observed in all constructs, which suggest a potential role of SREBP in the control of SND1 expression, without discarding the involvement of addi- tional transcription factors regulators of hepatic lipid metabolism. Supported by UPV-PIFA/01/2006/001. doi:10.1016/j.chemphyslip.2009.06.007 PO 6 Effects of alkaline sphingomyelinase on cholesterol absorption in intestinal Caco-2 cells Dan Feng ∗ , Lena Ohlsson, Rui-Dong Duan Gastroenterology Laboratory, Institution of Clinical Sciences, Lund Uni- versity, Lund, Sweden Background: Sphingomyelin (SM) is present in several dietary prod- ucts and in cell plasma membranes. SM has strong interaction with cholesterol. We previously showed that SM in the diet inhib- ited cholesterol absorption. The key enzyme in the intestinal tract that hydrolyses SM is alkaline sphingomyelinase (alk-SMase). The present study is to investigate the role of alk-SMase in cholesterol absorption in human intestinal Caco-2 cells. Methods: Micelles composed of bile sat, monoacylglycerol, and radio labeled cholesterol ( 14 C-cholesterol) were prepared by son- ication and then incubated with Caco-2 cells. After incubation, 0009-3084/$ – see front matter