CONICET | Buscador de Institutos y Recursos Humanos

Unraveling intestinal fatty acid binding proteins functions: analysis of FABP-membrane and FABP-protein interactions. Lisandro J. Falomir Lockhart#+, María Ximena Guerbi#, Gisela R. Franchinni#, Judith Storch¶ and Betina Córsico#+. # INIBIOLP, University of La Plata, Calle 60 y120, 1900, La Plata, Argentina. + Consejo Nacional de Investigaciones Científicas y Técnicas, Avda. Rivadavia 1917, C1033AAJ, Cdad. de Buenos Aires, Argentina. ¶ Department of Nutritional Sciences, Rutgers the State University of New Jersey, 96 Lipman Dr, New Brunswick, NJ, 08901-8525, U.S.A. e-mail: lysfalomir@yahoo.com.ar, bcorsico@atlas.med.unlp.edu.ar Introduction: Intestinal enterocytes express large concentrations of two homologous fatty acid binding proteins (FABPs): intestinal FABP (IFABP) (15.1 kDa) and liver FABP (LFABP) (14.2 kDa). It has long been hypothesized that FABPs participate in the intracellular transport and processing of the large quantities of fatty acids (FA) absorbed by the intestine, but their specific function are still poorly understood. In particular, it is currently not known why a single cell type contains two distinct types of FABP. Objective: We expect to identify the interaction partners of intestinal FABPs in order to describe the molecular crosstalk relevant for its biological functions. Methods: In this work, we took advantage of different structural variants of intestinal FABPs and a battery of biochemical and biophysical methodologies to analyze its interaction with membranes and other proteins. Tb/DPA complex leakage, binding to sucrose loaded vesicles, Cyt c competition assay and radiolabeled photoactivable phospholipid crosslinking were employed to study different factors (vesicle curvature, ligand nature, lipid composition, etc) that modulate the interaction of FABPs with artificial model membranes. On the other hand, a fluorescence based assay was employed to analyze colisional transfer of fatty acid analogs between IFABP and LFABP in a stopped-flow module. Results: Lipid composition and ligand binding show strong changes in membrane interaction properties of IFABP and LFABP, as evidenced by different techniques. Collisional transfer of fluorescent fatty acids suggests functional interaction between these intestinal FABPs. Conclusions: Intestinal FABPs could interact differentially with each other and with subcellular membranous fractions accordingly with ligand binding. The results in vitro presented here may reflect in vivo functions of intestinal FABPs. Increasing evidence supports the idea that FABPs participate and modulate several cell functions and further studies will be needed to unravel its physiological role. Rules: The abstracts should preferentially be written in English. We request all participants to have their texts in English revised, if necessary, prior to submission so as to facilitate the processing of abstracts. Abstracts submitted as an open presentation will be presented as posters and shall be revised by the Scientific Committee. The title of the abstract should be in upper case and followed by the names of the authors, Department, Institution and State where the research was performed. To guarantee that your name is shown correctly, please standardize the order of your name in all abstracts where you are the author or co-author. On your abstract use bold only on titles of Objectives, Methods, Results and Conclusion. Quotes should be kept to a minimum but if present, periodicals should be mentioned in abbreviated form, volume: first page-last page, year (e.g.: Brain Res. 472:24-40, 1992). Quotes such as: Ashley et al., 1994, shall not be accepted. Graduation students should be identified on the abstract with one asterisk and post-graduation students with two. Quantitative abstracts shall not be accepted without numerical data (e.g.: mean and standard deviation; control percentage, etc). Bibliographical references on abstracts follow distinct criteria from those on full articles. Dimension: the poster should be 0.90m by 1.20m(h) Title: the title should be the same as used on the summary and be written in upper case, allowing it be read from a 3m distance (suggested font: Arial, size 120 or larger). Under the title and in smaller font (suggested font: Arial, size 90), should appear the names of the authors, the laboratory, the department, institution, city and state. The name of the presenting author should be underlined. The poster should be prepared with a minimum of written text (suggested font: Arial, size 20) and a maximum of illustrations (figures, diagrams and tables). It is suggested that the Conclusion be " bulleted ". Summary in English: if the poster is not presented in English please put the summary of the poster in English on the bottom right-hand corner. Suggestion: the poster may be printed on A4 sheets to be distributed to interested participants.