Mice with Tissue Inhibitor of Metalloproteinases 4 (Timp4) Deletion Succumb to Induced Myocardial Infarction but Not to Cardiac Pressure Overload

Abstract

Tissue inhibitor of metalloproteinases 4 (TIMP4) is expressed highly in heart and found dysregulated in human cardiovascular diseases. It controls extracellular matrix remodeling by inhibiting matrix metalloproteinases (MMPs) and is implicated in processes including cell proliferation, apoptosis, and angiogenesis. Timp4-deficient mice (Timp4 ؊/؊ ) were generated to assess TIMP4 function in normal development and in models of heart disease. We deleted exons 1-3 of the Timp4 gene by homologous recombination. Timp4 ؊/؊ mice are born healthy, develop normally, and produce litters of normal size and gender distribution. These mice show no compensation by overexpression of Timp1, Timp2, or Timp3 in the heart. Following cardiac pressure overload by aortic banding, Timp4 ؊/؊ mice have comparable survival rate, cardiac histology, and cardiac function to controls. In this case, Timp4 deficiency is compensated by increased cardiac Timp2 expression. Strikingly, the induction of myocardial infarction (MI) leads to significantly increased mortality in Timp4 ؊/؊ mice primarily due to left ventricular rupture. The post-MI mortality of Timp4 ؊/؊ mice is reduced by administration of a synthetic MMP inhibitor. Furthermore, combining the genetic deletion of Mmp2 also rescues the higher post-MI mortality of Timp4 ؊/؊ mice. Finally, Timp4 ؊/؊ mice suffer reduced cardiac function at 20 months of age. Timp4 is not essential for murine development, although its loss moderately compromises cardiac function with aging. Timp4 ؊/؊ mice are more susceptible to MI but not to pressure overload, and TIMP4 functions in its capacity as a metalloproteinase inhibitor after myocardial infarction.Tissue inhibitors of metalloproteinases (TIMPs) 5 comprise a family of four endogenous inhibitors. Classically, matrix metalloproteinases (MMPs) and TIMPs are known as important regulators of extracellular matrix turnover during physiologic and numerous pathologic processes. Several other functions also have been ascribed to MMPs, many of which extend to their inhibitors (1). TIMPs also exhibit functions that appear to be independent of their metalloproteinase inhibitory capacity (2).TIMP4 is the most recently discovered member of the TIMP family. It inhibits several soluble MMPs (types 1, 2, 3, 7, 8, 9, 12, 13, 19, and 26) and membrane-type MMPs (MT1, MT2, and MT3) (3-7). TIMP4 also inhibits a disintegrin and metalloproteinase (ADAM) 28 and ADAM33 (7) but not ADAM10 (which is inhibited by TIMP1 and TIMP3) or ADAM17 (which is inhibited only by TIMP3) (2,7,8). Inhibition of the ADAMTS (ADAM with thrombospondin motifs) family by TIMP4 has not yet been reported. Although Timp genes 1, 2, and 3 are widely expressed, the Timp4 gene exhibits a restricted tissue expression pattern, with the highest expression in the heart, followed by brain, ovary, and skeletal muscle, and TIMP4 protein is detectable in the serum (9 -11). Several lines of evidence suggest a specific role in cardiovascular pathology: Timp4 is induced following endothelial injury of rat carotid art...

High-Fiber Diet and Acetate Supplementation Change the Gut Microbiota and Prevent the Development of Hypertension and Heart Failure in Hypertensive Mice

“…One hundred ninetytwo genes were in common between high fiber and acetate ( Figure 6C and 6D) such as the upregulation of genes thought to have a preventive role for heart disease such as titin-cap (Tcap) 27 and tissue metallopeptidase inhibitor 4 (Timp4). 28 It is interesting to note that in both the kidney and heart, fiber and acetate downregulated the gene for early growth response protein 1 (Egr1) mRNA ( Figure 6D), a master regulator of cardiovascular pathology. [29][30][31] Several of these common genes were in the same pathways, and they formed interconnected networks ( Figure ure 6E) and acetate supplementation ( Figure VII in the online-only Data Supplement) upregulated several pathways acting on cell cycle, DNA replication, translation, mRNA metabolism, and respiratory electron chain.…”

Cardiac-restricted overexpression or deletion of tissue inhibitor of matrix metalloproteinase-4: differential effects on left ventricular structure and function following pressure overload-induced hypertrophy

“…However, this past study was performed on a different background strain and with a different magnitude of PO stimulus, which make direct comparisons on the effects of LVPO difficult. For example, the pressure gradient in the study by Koskivirta and colleagues by aortic constriction was 60 -70 mmHg (17), whereas the target pressure gradient of the present study was 90 mmHg. Nevertheless, the present study extended the work from this past report by examining the comparative effects of TIMP-4 deletion as well as overexpression.…”

“…Changes in ECM structure and function have been recognized as important events in the progression of LV remodeling and dysfunction in a number of cardiovascular disease states, such as that of ischemia, LVPO, and idiopathic underpinnings (8,16,17,24,27,29,34,36,37). For example, in ischemia/ infarction an imbalance between MMPs and TIMPs has been identified, which would favor ECM proteolysis and thereby contribute to changes in myocardial geometry and function (23,27).…”

“…The present study utilized transgenic models to modify TIMP-4 and as such holds inherent limitations. Specifically, TIMP-4 gene deletion was a global deletion, and while this study and past studies have failed to identify any developmental/phenotype abnormalities in this construct in the absence of a pathological stimulus (17), this approach lacks temporal and spatial specificity relative to the LVPO stimulus. In addition, this study examined specific aspects of LV remodeling and MMP/TIMP at 1 mo following LVPO.…”

“…Moreover, LV dilation was more profound in the TIMP-4KO mice compared with TIMP-4OE or wild-type mice. In a previous study by Koskivirta and colleagues (17), LVPO as well as myocardial infarction were performed in TIMP-KO mice, whereby the most pronounced effects of TIMP-4 gene deletion was following myocardial infarction. While not the primary focus of this past study, there was a relative reduction in early survival following LVPO in the TIMP-4KO mice, not dissimilar to that observed in the present Fig.…”