Expression and Localization of the Annexins II, V, and VI in Myocardium from Patients with End-Stage Heart Failure

Abstract

SUMMARY:Annexins II, V, and VI belong to a family of Ca 2ϩ -dependent phospholipid-binding proteins that have been involved mainly in signal transduction, differentiation, membrane trafficking events, or binding to the extracellular matrix, or that might be effective as Ca 2ϩ -channels. They are abundant in the mammalian myocardium and might play a role in ventricular remodeling and altered calcium handling during heart failure. To test this hypothesis, we compared the expression and distribution of these annexins in nonfailing (n ϭ 9) and failing human hearts with idiopathic dilated cardiomyopathy (n ϭ 11). Northern blot and slot blot analysis were used to determine the annexin mRNA levels and Western blots were used to quantify the amounts of annexin proteins. Distribution of annexins was studied by immunohistofluorescence labeling and compared with that of a sarcolemmal marker (Na ϩ /K ϩ -ATPase) and of a myofibrillar protein (␣-actinin). We showed that nonfailing hearts contained a higher amount of annexin VI than of annexin V or II (13.5 Ϯ 1.8, 3.7 Ϯ 0.2, and 2.5 Ϯ 0.5 g/mg protein, respectively). In failing hearts, there was a parallel increase in both mRNA and protein levels of annexin II (146% and 132%, p Ͻ 0.05, respectively) and annexin V (152%, p Ͻ 0.01, 147%, p Ͻ 0.005, respectively); the protein level of annexin VI was also increased (117%, p Ͻ 0.05), whereas the increase of its mRNA level was statistically insignificant. We observed a predominant localization of annexin II in interstitium, and of annexins V and VI in cardiomyocytes at the level of the sarcolemma, T-tubules, and intercalated disks in nonfailing hearts, whereas in failing hearts enlarged interstitium contained all three annexins. Furthermore, annexin V staining at the level of cardiomyocytes almost disappeared. In conclusion, we showed that heart failure is accompanied by marked overexpression of annexins II and V, as well as translocation of annexin V from cardiomyocytes to interstitial tissue. The data suggest that annexins may contribute to ventricular remodeling and annexin V to impaired Ca 2ϩ handling in failing heart. (Lab Invest 2000, 80:123-133).

Protein kinetic signatures of the remodeling heart following isoproterenol stimulation

“…We further performed immunoblotting experiments on some proteins of interest as an orthogonal technique to validate the abundance measurements. ANXA2 and ANXA5 proteins both increased in abundance in the failing heart ( Figure 6B), consistent with previous reports (25,26). Also expectedly, immunoblots failed to detect evidence for increased expression of the tested glycolytic proteins.…”

“…ANXA2/3/4/5 changed most prominently in the remodeling heart (1.7-to 3.0-fold, 86th-98th percentile rank) (Figure 2A), translating, for example, into a decrease in the ANXA2 half-life from 16.7 to 5.5 days, whereas ANXA6 and ANXA7 were also significantly elevated (1.4-fold). ANXA2 and ANXA5 are widely known to have elevated transcript and protein levels in heart failure patients (25,26), but consensus is lacking on the other isoforms. The broadly increased kinetics among six isoforms provides new evidence that annexins may be generally associated with cardiac remodeling and hypertrophy.…”

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

“…To compare the localization of TUNEL-positive myocytes with those of annexin A5 and of Na ϩ -K ϩ -ATPase, we used serial cryosections (7-10 m) because primary antibodies were both rabbit polyclonal antibodies (4,9). After fixation in acetone-methanol (1:1) for 20 min at Ϫ20°C, sections were saturated with 5% bovine serum albumin in phosphate-buffered saline and incubated with either antiannexin A5 antibodies or anti-Na ϩ -K ϩ -ATPase antibodies (1:20, 1:50, respectively).…”

“…In line with these findings, Monceau et al (28) have previously demonstrated in cardiomyocytes that endogenous annexin A5, which was externalized during apoptosis, exhibited a proapoptotic effect. Annexin A5, an abundant protein of the cardiomyocyte, has been located in both the cytosol and the sarcolemma in control hearts and is found in the interstitial tissue in the failing heart (4,38). Apoptosis of cardiomyocytes has been largely reported in acute myocardial infarction (MI) and ischemia reperfusion and occurs preferentially in the border area around the necrotic core (10,18,23,30).…”

Effect of water-soluble fraction of cigarette smoke on human aortic endothelial cells – a proteomic approach

“…They may also be relevant to fibrosis and remodeling of cardiovascular system (Benevolensky et al, 2000;Trouve et al, 1999). Although on the surface this may appear to be contradictory to the global pro-thrombotic effects by the cigarettes, one must bear in mind that annexin expression in endothelial cells only represents one small aspect of the entire thrombotic cascades.…”