Glycoprotein IIb/IIIa Antagonists Induce Apoptosis in Rat Cardiomyocytes by Caspase-3 Activation

Adderley, Sharon R.; Fitzgerald, Desmond J.

doi:10.1074/jbc.275.8.5760

Cited by 89 publications

(53 citation statements)

References 32 publications

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“…One possibility is that soluble complexes may elicit different integrin signals than the attachment of cells to a substrate, which promotes survival. Accumulation of RGD-containing peptides in the cytoplasm has been reported to initiate apoptosis (33,34); internalization and proteolysis of antiangiogenic factor/adhesion protein complexes could provide a supply of cytoplasmic RGD peptides. Alternatively, the integrin-binding complexes could bind to circulating endothelial precursor cells (35), preventing them from contributing to the formation of new blood vessels.…”

Section: Discussionmentioning

confidence: 99%

Antiangiogenic proteins require plasma fibronectin or vitronectin for in vivo activity

Sakai

Fässler

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

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Fragmentation of various extracellular matrix and blood proteins generates antiangiogenic substances that are physiological regulators of angiogenesis. Some of these compounds are in clinical trials as inhibitors of tumor angiogenesis. Anastellin, an antiangiogenic protein fragment derived from fibronectin, was unable to inhibit matrigel plug angiogenesis in mice that lack plasma fibronectin. Anastellin was fully active in mice that are null for vitronectin, which, like fibronectin, is a major adhesion protein in the blood. An antiangiogenic form of antithrombin showed the opposite pattern. The activity of endostatin was impaired in both fibronectin-and vitronectin-deficient mice. These results suggest a shared mechanism of action for antiangiogenic factors derived from extracellular matrix and plasma proteins: these factors form complexes with adhesion proteins in plasma to create an active antiangiogenic substance.A growing class of antiangiogenic substances is derived from extracellular matrix and blood proteins by proteolysis or other modifications. These substances include fragments from thrombospondin (1), plasminogen (angiostatin; ref. (5), and the fibronectin fragment anastellin (6, 7). The molecular mechanisms whereby these substances exert their antiangiogenic activities are poorly understood. Anastellin binds to and polymerizes fibronectin and fibrinogen (8, 9). The antiangiogenic form of antithrombin is similar to the modified antithrombin that binds vitronectin (10, 11). Vitronectin, like fibronectin, is an arginine-glycine-aspartic acid (RGD)-containing adhesion protein present in plasma (12). Other angiogenesis inhibitors also interact with one or more adhesion proteins: angiostatin and its parent protein, plasminogen, bind vitronectin (13), whereas endostatin binds fibulins and nidogen-2 (14).The interactions of the various angiogenesis inhibitors with adhesion proteins led us to hypothesize that adhesion protein binding could underlie antiangiogenic activity, and that activities of the various inhibitors could converge on this ability to form such adhesion protein complexes (7). To test this hypothesis, we examined the two antiangiogenic proteins with the most extensively documented adhesion protein interactions, anastellin and antithrombin. We used angiogenesis induced by implanting matrigel (basement membrane) plugs (15, 16) into mutant mice that conditionally lack plasma fibronectin (17) or have their vitronectin gene knocked out (18).We show here that anastellin does not suppress angiogenesis in matrigel plugs implanted into mice that lack plasma fibronectin. In contrast, the antiangiogenic form of antithrombin is inactive in mice that lack vitronectin. Endostatin is essentially inactive in mice that lack either plasma fibronectin or vitronectin. These results strongly support the hypothesis that the activity of extracellular matrix-and blood protein-derived angiogenesis inhibitors depends on interactions with adhesion proteins. Materials and MethodsProteins. Anastellin (a fragment from the...

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Section: Discussionmentioning

confidence: 99%

Antiangiogenic proteins require plasma fibronectin or vitronectin for in vivo activity

Sakai

Fässler

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

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“…The previously reported apoptotic changes in response to hypoxia in neonatal cultured cardiomyocytes (10 -14) may not adequately represent the in vivo situation as well as our model does. This could possibly be because of the loss of survival signals emanating from the extracellular matrix in the intact heart when cardiomyocytes are grown in culture (37,38). Moreover, many of the previous reports that demonstrated cardiac apoptosis in cell culture experiments used shorter duration, but more severe, hypoxia compared with our model.…”

Section: Discussionmentioning

confidence: 77%

Modulation of Ceramide Content and Lack of Apoptosis in the Chronically Hypoxic Neonatal Rat Heart

Bitar

Sabban

et al. 2002

Pediatr Res

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To assess the effect of chronic hypoxia on cardiomyocyte apoptosis, we used an animal model that mimics cyanotic heart disease. Rats were placed in a hypoxic environment at birth, and oxygen levels were maintained at 10% in an air-tight Plexiglas chamber. Controls remained in room air. Animals were killed, and the hearts were harvested at 1 and 4 wk. Significant polycythemia developed in the hypoxic rats at 1 and 4 wk. Right ventricular mass in the hypoxic rats was 192% and 278% that of controls, and hypoxic left ventricular mass was 140% and 178% that of the controls at 1 and 4 wk, respectively. The increase in cardiac mass was paralleled by only mild hypertrophy (10 to 20%). Contrary to previous reports showing increased apoptosis in response to hypoxia in cultured cardiomyocytes, there was no difference in the number of apoptotic cardiomyocytes between the chronically hypoxic rats and controls, as assayed by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling and Hoechst staining. We then examined the role of the sphingolipid ceramide because of its reported role in the stress response, growth suppression, and apoptosis. We found that the right ventricular ceramide content was significantly decreased in the hypoxic rats to 73% of control levels at the age of 4 wk. We suggest that the decrease in the ceramide content in the hypoxic right ventricular rat heart may be an adaptive response to chronic hypoxia and pulmonary hypertension. Lower ceramide levels may help suppress apoptosis and allow compensatory right ventricular cardiomyocyte proliferation. Apoptosis, or programmed cell death, is a mechanism of regulated cell death that plays a major role during development and homeostasis, and in many disease states. Apoptosis in cardiomyocytes has been demonstrated after injury caused by ischemia and reperfusion (1, 2), myocardial infarction (3, 4), cardiac aging (5), ventricular pacing (6), heart failure, and coronary embolization (7,8).Conflicting data regarding apoptotic changes, in response to hypoxia, have been described (9 -12). The failing myocardium is subject to regional ischemia and hypoxia, an abnormality that can trigger cardiomyocyte apoptosis (13). Long et al. (14) reported that cultured neonatal rat cardiomyocytes exposed to in vitro hypoxia for 48 h exhibited apoptotic changes. However, Bishopric et al. (15) found that induction of apoptosis of cardiac myocytes by hypoxia required acidosis, and that chronic hypoxia alone did not cause apoptosis of cardiomyocytes in culture. Hypoxia can induce cellular adaptive responses, such as c-Jun expression, that overcome apoptosis signals to minimize injury or damage (16). The in vivo effect of chronic hypoxia on the neonatal heart has not been investigated, and differentiating the effect of hypoxia and ischemia from that of hypoxia alone on apoptosis in the neonatal heart is important.Although no universal definition of apoptosis currently exists, morphologic and biochemical characteristics of apoptosis have been described that distinguis...

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“…They also do not activate caspase-3 directly by interacting with Arg-Gly-Asp (RGD)-binding motif of pro-caspase-3, as was reported for cell-penetrating GPIIbIIIa antagonists, orbofiban and xemilofiban, in rat cardiomyocytes, 5 indicating that the chemically different Integrilin and Aggrastat do not penetrate human platelets.…”

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confidence: 81%

The GPIIbIIIa antagonist drugs eptifibatide and tirofiban do not induce activation of apoptosis executioner caspase-3 in resting platelets but inhibit caspase-3 activation in platelets stimulated with thrombin or calcium ionophore A23187

Leytin¹,

Mutlu²,

Mykhaylov³

et al. 2009

Haematologica

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The GPIIbIIIa antagonist drugs eptifibatide and tirofiban do not induce activation of apoptosis executioner caspase-3 in resting platelets but inhibit caspase-3 activation in platelets stimulated with thrombin or calcium ionophore A23187Platelet surface receptor, glycoprotein (GP) IIbIIIa (integrin αIIbβ3), mediates platelet aggregation and plays a key role in hemostasis and thrombosis. 1,2Numerous GPIIbIIIa antagonists have been designed and tested as inhibitors of platelet aggregation.3 Two of these antagonists, eptifibatide (Integrilin) and tirofiban (Aggrastat), are approved by the US Food and Drug Administration (FDA) for clinical use for preventing and treating thrombotic complications in patients undergoing percutaneous coronary intervention and in patients with acute coronary syndromes.4 It has been reported, however, that some GPIIbIIIa antagonists, such as orbofiban and xemilofiban, promote apoptosis in cardiomyocytes by activation of the apoptosis executioner caspase-3, 5 raising the possibility that platelets also may be susceptible to pro-apoptotic effects of Integrilin and Aggrastat.Over the past decade it has been well-documented by us and others that apoptosis occurs not only in nucleated cells but also in anucleated platelets stimulated with thrombin, calcium ionophores, very high shear stresses and platelet storage (see references in [6][7][8] ). It has been further reported that platelet activation and apoptosis may be induced by different mechanisms and/or require different levels of triggering stumuli.9,10 Recently, we have shown that injection of anti-GPIIb antibody induced caspase-3 activation in mouse platelets, 11 suggesting that direct GPIIbIIIa-mediated pro-apoptotic signaling is able to trigger caspase-3 activation within platelets.The current study aimed to examine, for the first time, the effect of Integrilin and Aggrastat on caspase-3 activation in human platelets. We studied the effects of Integrilin and Aggrastat on caspase-3 activation in resting platelets which express GPIIbIIIa receptors in their nonactive (closed) conformation, and in platelets stimulated with thrombin and calcium ionophore A23187, which induce transition of GPIIbIIIa receptors into active (open) conformation. Table 1A shows that treatment of resting platelets with Integrilin and Aggrastat did not affect caspase-3 activation (p>0.05). In contrast, a 2.3-2.7-fold increase in caspase-3 activation was observed in platelets after thrombin and A23187 stimulation (Table 1B and C, p<0.01). However, when platelets were preincubated with Integrilin and Aggrastat before agonist treatment, these drugs significantly inhibited agonist-induced caspase-3 activation ( Figure 1 and Table 1B and C, p<0.05).The fact that Integrilin and Aggrastat do not promote caspase-3 activation in unstimulated platelets (Table 1A) suggests that these GPIIbIIIa antagonists do not induce transmission of pro-apoptotic transmembrane signals inside platelets through inactive GPIIbIIIa integrin. They also do not activate caspase-3 directly by inte...

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Glycoprotein IIb/IIIa Antagonists Induce Apoptosis in Rat Cardiomyocytes by Caspase-3 Activation

Cited by 89 publications

References 32 publications

Antiangiogenic proteins require plasma fibronectin or vitronectin for in vivo activity

Antiangiogenic proteins require plasma fibronectin or vitronectin for in vivo activity

Modulation of Ceramide Content and Lack of Apoptosis in the Chronically Hypoxic Neonatal Rat Heart

The GPIIbIIIa antagonist drugs eptifibatide and tirofiban do not induce activation of apoptosis executioner caspase-3 in resting platelets but inhibit caspase-3 activation in platelets stimulated with thrombin or calcium ionophore A23187

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