CONICET | Buscador de Institutos y Recursos Humanos

Vascular chondroitin/dermatan sulfate proteoglycans remodeling induced by ApoA- I and natural variants. Probable role in settlement of amyloidosis.AC Eiguren1, F Funez1, AM Birocco1, S Rosu2, A Tricerri2, GC Calabrese1Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Ciencias Biológicas. Cátedra de Biología Celular y Molecular. Junín 954, Primer Piso, (C1113AAD) Buenos Aires, Argentina.2Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), CONICET, La Plata, Buenos Aires, Argentina.Introduction Amyloidosis constitutes a heterogeneous group of diseases involving protein misfolding and deposition of fibrils. Apolipoprotein A-I (apoA-I), the main protein of plasma high-density lipoproteins (HDL), removes excess cell cholesterol and protects against atherosclerosis. Nevertheless, some natural variants (R173P) or their N-terminal fragments (IOWA, N-terminal peptide of G26R) of the native protein with structural disorder elicit their propensity to suffer misfolding or aggregation. Moreover, amyloidosis due to the protein with the native sequence has been described as diffuse protein aggregates in atherosclerotic plaques. Our previous reports suggest that specific interactions of apoA-I with glycosaminoglycans could elicit its retention and/or aggregation. Furthermore, recent studies indicate that protein cores of proteoglycans (PGs) may influence the type and modification patterns of the subsequently attached glycosaminoglycan chains. We hypothesize that mutations in human apoA-I may affect the core protein pattern expression of vascular chondroitin/dermatan sulfate PGs, modulating chemical changes in the glycosylation pattern which elicit extracellular apoA-I aggregation. Materials and MethodsWT apoA-I and the amyloidogenic mutants IOWA and R173P were obtained by molecular biology techniques. Human umbilical vein endothelial cells (HUVEC) were treated with 1.5-50 µg/ml for 24hs. MTT, immunofluorescence of NFκB and zymographic analysis were used to evaluate endothelial activation. PG protein cores were quantified using RT-PCR for decorin, biglycan and versican.ResultsWT, R173P or IOWA (1.5 µg/ml) treatment did not modify cell viability, NFκB nuclear translocation and metalloproteinase-2 and -9 activities. Decorin expression was significantly decreased by WT and R173P, 10 and 6 folds respectively, when it was compared with no treated cells (control). Whereas biglycan was increased 4-fold by IOWA variant. And versican expression was only detected after R173P treatment.DiscussionWT and the studied natural variants do not elicit an inflammatory response in our experimental model. Nevertheless, our results indicate substantial modifications in the profile of chondroitin/dermatan sulfate PGs core proteins, depending on the protein or peptide employed. Considering that glycosaminoglycans polymerization and modification by sulfation and epimerization are influenced by the protein core; changes in the profile of PGs might be involved directly or indirectly in the equilibrium between protein function and citotoxicity.