Annexin 5 overexpression increased articular chondrocyte apoptosis induced by basic calcium phosphate crystals.

Objectives: Basic calcium phosphate (BCP) crystals (octacalcium phosphate (OCP), carbapatite (CA) and hydroxyapatite (HA)) are associated with severe forms of osteoarthritis. In advanced osteoarthritis, cartilage shows chondrocyte apoptosis, overexpression of annexin 5 (A5) and BCP crystal deposition within matrix vesicles. We assessed in vitro whether BCP crystals and overexpression of A5 increased chondrocyte apoptosis.

Reduced myocardial expression of calcium handling protein in patients with severe chronic mitral regurgitation.

Objective: Left ventricle (LV) function was shown to be a principal determinant of morbidity and mortality in both uncorrected and surgically corrected mitral regurgitation (MR). However, the cellular mechanisms that develop in the LV remodeling secondary to volume overload in chronic severe MR is still not well defined. In single ventricular myocyte, a reduced contraction and slowed relaxation have been mainly attributed to defective intracellular Ca2+ currents.

Myocyte apoptosis during acute myocardial infarction in rats is related to early sarcolemmal translocation of annexin A5 in border zone.

Annexin A5 is a Ca2+-dependent phospholipid binding protein well known for its high phosphatidylserine affinity. In vitro, translocation to sarcolemma and externalization of endogenous annexin A5 in the cardiomyocyte has recently been demonstrated to exert a proapoptotic effect. To determine whether these in vitro findings occurred in vivo, we performed myocardial infarction (MI) and studied the time course of apoptosis and annexin A5 localization (0.

Association of annexin A5 with Na+/Ca2+ exchanger and caveolin-3 in non-failing and failing human heart.

Annexin A5 is a Ca2+ dependent phosphatidylserine binding protein mainly located in the T-tubules and sarcolemma of cardiomyocytes. Our objectives were to determine whether annexin A5 was associated with various protein(s) and whether such an association was modified in failing (F) hearts. The association between annexin A5 and the cardiac Na+/Ca2+ exchanger (NCX) was demonstrated by immunohistofluorescence, annexin A5-biotin overlay and co-immunoprecipitations (IPs) performed with microsomal preparations (MPs) from non-failing (NF) (n = 8) and F (dilated cardiomyopathy, n = 7) human hearts.

Annexins and Ca2+ handling in the heart.

Annexins are a family of 13 proteins known to bind phospholipids (PL) in a Ca(2+)-dependent way. They are ubiquitous proteins and share a similar structure characterized by a conserved C-terminal domain with Ca(2+) binding sites and a variable N-terminal domain. Depending on Ca(2+) concentration, they have been reported to participate in a variety of membrane-related events such as exocytosis, endocytosis, apoptosis and binding to cytoskeletal proteins.