Interactions of human apolipoprotein A-I with component of the extracellular matrix, probable role I in amyloidosis

ROSU SILVANA A.; SANCHEZ DONOSO SUSANA; M. A. TRICERRI; BARANDIARAN, ALDANA; TOLEDO, LEANDRO; URBANO, BRUNO; CALABRESE, GRACIELA C.

Kumamoto

Simposio; XVI th International Symposium on Amyloidosis; 2018

International Soc of amyloidosis

Human apolipoprotein A-I (apoA-I)-derived amyloidosis can present with either wild-type (Wt) protein deposits in atherosclerotic plaques or as a hereditary form in which apoA-I variants deposit causing multiple organ failure. A number of naturally occurring mutations of the apoA-I have been associated with hereditary amyloidoses. The molecular mechanisms involved in this pathology remain largely unknown but our previous studies strongly suggest that changes in the microenvironment could elicit protein misfolding and tissue deposition. Among other components of the extracellular matrix (ECM), glycoproteins and glycosaminoglycans (GAGs) have been strongly associated to the retention or misfolding of different proteins inducing the formation of deposits in amyloid diseases. Thus, we set out here to analyze the possible role of GAGs on apoA-I amyloidosis. Interestingly Arg173Pro (a natural mutant involved in cardiac amyloidosis) forms heparin/protein complexes at pH 7.4 with higher efficiency than Wt. We checked and compared by fluorescence techniques the binding of Wt and this mutant to hydrogel scaffolds. Our results indicate that both proteins are highly retained as long as the negative charge increases, and in addition it was shown that the mutant is more retained than the Wt, indicating that the retention of specific proteins in the ECM could be part of the pathogenicity. In order to evaluate citotoxicity by MTT assays, human umbilical vein endothelial cells (HUVEC) were cultured for 24 hs in the presence of increasing doses of apoA-I (1.5?100 µg/mL). No cell cytotoxicity was determined through all the apoA-I doses analyzed. Finally we analyzed the core protein expression by RT-PCR and the glycosaminoglycan biosynthetic enzymes of proteoglycans (PGs) in HUVEC in the presence of 1.5 ug/ml of Wt. After treatment the apolipoprotein was able to induce a PG remodeling in human endothelial cells with prevalence in chondroitin sulfate glycosaminoglycan chains. We conclude that the interactions among apoA-I variants with PGs offer a challenging field which must be understood to halt the devastating consequences of this pathology..