Mitochondrial matrix metalloproteinase activation decreases myocyte contractility in hyperhomocysteinemia.

Abstract

Cardiomyocyte N-methyl-d-aspartate receptor-1 (NMDA-R1) activation induces mitochondrial dysfunction. Matrix metalloproteinase protease (MMP) induction is a negative regulator of mitochondrial function. Elevated levels of homocysteine [hyperhomocysteinemia (HHCY)] activate latent MMPs and causes myocardial contractile abnormalities. HHCY is associated with mitochondrial dysfunction. We tested the hypothesis that HHCY activates myocyte mitochondrial MMP (mtMMP), induces mitochondrial permeability transition (MPT), and causes contractile dysfunction by agonizing NMDA-R1. The C57BL/6J mice were administered homocystinemia (1.8 g/l) in drinking water to induce HHCY. NMDA-R1 expression was detected by Western blot and confocal microscopy. Localization of MMP-9 in the mitochondria was determined using confocal microscopy. Ultrastructural analysis of the isolated myocyte was determined by electron microscopy. Mitochondrial permeability was measured by a decrease in light absorbance at 540 nm using the spectrophotometer. The effect of MK-801 (NMDA-R1 inhibitor), GM-6001 (MMP inhibitor), and cyclosporine A (MPT inhibitor) on myocyte contractility and calcium transients was evaluated using the IonOptix video edge track detection system and fura 2-AM. Our results demonstrate that HHCY activated the mtMMP-9 and caused MPT by agonizing NMDA-R1. A significant decrease in percent cell shortening, maximal rate of contraction (-dL/dt), and maximal rate of relaxation (+dL/dt) was observed in HHCY. The decay of calcium transient amplitude was faster in the wild type compared with HHCY. Furthermore, the HHCY-induced decrease in percent cell shortening, -dL/dt, and +dL/dt was attenuated in the mice treated with MK-801, GM-6001, and cyclosporin A. We conclude that HHCY activates mtMMP-9 and induces MPT, leading to myocyte mechanical dysfunction by agonizing NMDA-R1.

• Authors: Karni S Moshal, Srinivas M Tipparaju, Thomas P Vacek, Munish Kumar, Mahavir Singh, Iluiana E Frank, Phani K Patibandla, Neetu Tyagi, Jayesh Rai, Naira Metreveli, Walter E Rodriguez, Michael T Tseng, Suresh C Tyagi
• Journal: American journal of physiology. Heart and circulatory physiology (Am J Physiol Heart Circ Physiol) Vol. 295 Issue 2 Pg. H890-7 (Aug 2008) ISSN: 0363-6135 [Print] United States
• PMID: 18567713 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Dipeptides
• Excitatory Amino Acid Antagonists
• Matrix Metalloproteinase Inhibitors
• Mitochondrial Membrane Transport Proteins
• Mitochondrial Permeability Transition Pore
• N-(2(R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl)-L-tryptophan methylamide
• Protease Inhibitors
• Receptors, N-Methyl-D-Aspartate
• Dizocilpine Maleate
• Cyclosporine
• Matrix Metalloproteinase 9
• Mmp9 protein, mouse

Topics

• Animals
• Blotting, Western
• Calcium Signaling
• Cell Size
• Cyclosporine (pharmacology)
• Dipeptides (pharmacology)
• Disease Models, Animal
• Dizocilpine Maleate (pharmacology)
• Enzyme Activation
• Excitatory Amino Acid Antagonists (pharmacology)
• Hyperhomocysteinemia (enzymology, pathology, physiopathology)
• Matrix Metalloproteinase 9 (metabolism)
• Matrix Metalloproteinase Inhibitors
• Mice
• Mice, Inbred C57BL
• Microscopy, Confocal
• Mitochondria, Heart (drug effects, enzymology, ultrastructure)
• Mitochondrial Membrane Transport Proteins (antagonists & inhibitors, metabolism)
• Mitochondrial Membranes (enzymology)
• Mitochondrial Permeability Transition Pore
• Myocardial Contraction (drug effects)
• Myocytes, Cardiac (drug effects, enzymology, ultrastructure)
• Permeability
• Protease Inhibitors (pharmacology)
• Receptors, N-Methyl-D-Aspartate (antagonists & inhibitors, metabolism)
• Time Factors