Mitochondrial matrix metalloproteinase activation decreases myocyte contractility in hyperhomocysteinemia.
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.
Department of Physiology and Biophysics, Potentia Pharmaceuticals, Louisville, KY, USA.
Karni S
KS
Moshal
Srinivas M
SM
Tipparaju
Thomas P
TP
Vacek
Munish
M
Kumar
Mahavir
M
Singh
Iluiana E
IE
Frank
Phani K
PK
Patibandla
Neetu
N
Tyagi
Jayesh
J
Rai
Naira
N
Metreveli
Walter E
WE
Rodriguez
Michael T
MT
Tseng
Suresh C
SC
Tyagi
D000818:Animals; D015153:Blotting, Western; D020013:Calcium Signaling; D048429:Cell Size; D016572:Cyclosporine / Q000494:pharmacology; D004151:Dipeptides / Q000494:pharmacology; D004195:Disease Models, Animal; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004789:Enzyme Activation; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D020138:Hyperhomocysteinemia / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D061965:Matrix Metalloproteinase Inhibitors; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D008929:Mitochondria, Heart / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure; D033681:Mitochondrial Membrane Transport Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D051336:Mitochondrial Membranes / Q000201:enzymology; D000083162:Mitochondrial Permeability Transition Pore; D009200:Myocardial Contraction / Q000187:drug effects; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure; D010539:Permeability; D011480:Protease Inhibitors / Q000494:pharmacology; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013997:Time Factors
D004151:Dipeptides; D018691:Excitatory Amino Acid Antagonists; D061965:Matrix Metalloproteinase Inhibitors; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; C078131:N-(2(R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl)-L-tryptophan methylamide; D011480:Protease Inhibitors; D016194:Receptors, N-Methyl-D-Aspartate; D016291:Dizocilpine Maleate; D016572:Cyclosporine; D020780:Matrix Metalloproteinase 9; C501830:Mmp9 protein, mouse