Homocysteine-mediated activation and mitochondrial translocation of calpain regulates MMP-9 in MVEC

Abstract

. Homocysteine-mediated activation and mitochondrial translocation of calpain regulates MMP-9 in MVEC. Am J Physiol Heart Circ Physiol 291: H2825-H2835, 2006. First published July 28, 2006 doi:10.1152/ajpheart.00377.2006 is associated with atherosclerosis, stroke, and dementia. Hcy causes extracellular matrix remodeling by the activation of matrix metalloproteinase-9 (MMP-9), in part, by inducing redox signaling and modulating the intracellular calcium dynamics. Calpains are the calcium-dependent cysteine proteases that are implicated in mitochondrial damage via oxidative burst. Mitochondrial abnormalities have been identified in HHcy. The mechanism of Hcy-induced extracellular matrix remodeling by MMP-9 activation via mitochondrial pathway is largely unknown. We report a novel role of calpains in mitochondrial-mediated MMP-9 activation by Hcy in cultured rat heart microvascular endothelial cells. Our observations suggested that calpain regulates Hcy-induced MMP-9 expression and activity. We showed that Hcy activates calpain-1, but not calpain-2, in a calcium-dependent manner. Interestingly, the enhanced calpain activity was not mirrored by the decreased levels of its endogenous inhibitor calpastatin. We presented evidence that Hcy induces the translocation of active calpain from cytosol to mitochondria, leading to MMP-9 activation, in part, by causing intramitochondrial oxidative burst. Furthermore, studies with pharmacological inhibitors of calpain (calpeptin and calpain-1 inhibitor), ERK (PD-98059) and the mitochondrial uncoupler FCCP suggested that calpain and ERK-1/2 are the major events within the Hcy/MMP-9 signal axis and that intramitochondrial oxidative stress regulates MMP-9 via ERK-1/2 signal cascade. Taken together, these findings determine the novel role of mitochondrial translocation of calpain-1 in MMP-9 activation during HHcy, in part, by increasing mitochondrial oxidative tress. cysteine proteases; thioredoxin; Nicotinamide adenine dinucleotide phosphate-oxidase-4; mitochondrial redox signaling; cardiovascular remodeling; calcium; extracellular regulated kinase 1/2; mitogenactivating protein kinase; calpastatin; antiproteolytic therapy; microvascular endothelial cells; matrix metalloproteinase-9 A GROWING BODY OF LITERATURE indicates that elevated levels of homocysteine [hyperhomocysteinemia (HHcy)] are an independent risk factor for coronary, cerebrovascular, and peripheral atherosclerotic diseases (5, 11, 12). Matrix metalloproteinases (MMPs) are the members of Zn-containing endopeptidases that share structural domains but differ in the substrate specificity, cellular sources, and induciblity that are responsible for matrix turnover. It is well known that Hcy-induced vascular dysfunction is caused by extracellular matrix remodeling. Hcy induces extracellular matrix remodeling by MMP-9 activation, in part, by inducing the redox signaling and modulating the intracellular calcium homeostasis (13,14,19,20).Calpains are the family of calcium-dependent cysteine proteases that have previously been i...

High Homocysteine Levels Predict the Recurrence of Atrial Fibrillation After Successful Electrical Cardioversion

“…3,4) It was also proven that Hcy can upregulate the activity of MMPs 2 and 9. 5,6) Another experimental study showed that Hcy could cause electro-physiological disturbances of potassium currents in human atrial myocytes. 14) On the other hand, recent data also support the involvement of Hcy in oxidative stress and reduced nitric oxide bioavailability in animal heart tis- sue.…”

“…3,4) It has been shown in animal studies that metalloproteinases in endocardial cells could be activated by homocysteine (Hcy). 5,6) Elevated levels of Hcy are associated with an increased risk of coronary artery disease and cerebrovascular disease. [7][8][9] One study showed that elevated levels of Hcy are associated with the presence of nonvalvular AF.…”

Fibrinogen induces endothelial cell permeability

“…Fg-induced phosphorylation of ERK was studied using a method described previously [36]. Confluent MVECs were serum starved for 16 h and incubated with one of the following: Fg (2 or 4 mg/ml), Fg (4 mg/ml) with antibody against ICAM-1 (50 μM), Fg (4 mg/ml) with antibodies against α 5 and β 1 , or β 3 integrins (50 μM each), or Fg (4 mg/ml) with MEK inhibitors PD98059 or U0126 (50 μM each) at 37°C for 30 min.…”

Cardiac N-methyl d-aspartate Receptors as a Pharmacological Target

“…Mitochondrial dysfunction was considered as one of the mechanisms of myocardial damage following NMDAR hyperactivation (45)(46)(47)(48)(49). Ca 2+ overload in cardiomyocytes was suggested to be involved in pathological response to the stimulation with high doses agonists of the NMDAR (47).…”