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Targeted inhibition of calpain reduces myocardial hypertrophy and fibrosis in mouse models of type 1 diabetes.

Li Y, Ma J, Zhu H, Singh M, Hill D, Greer PA, Arnold JM, Abel ED, Peng T - Diabetes (2011)

Bottom Line: Calpain activity, cardiomyocyte cross-sectional areas, and myocardial collagen deposition were significantly increased in both STZ-induced and OVE26 diabetic hearts, and these were accompanied by elevated expression of hypertrophic and fibrotic collagen genes.These effects were associated with a normalization of the nuclear factor of activated T-cell nuclear factor-κB and matrix metalloproteinase (MMP) activities in diabetic hearts.Thus targeted inhibition of calpain represents a potential novel therapeutic strategy for reversing diabetic cardiomyopathy.

View Article: PubMed Central - PubMed

Affiliation: Critical Illness Research, Lawson Health Research Institute, University of Western Ontario, London, Ontario, Canada.

ABSTRACT

Objective: Recently we have shown that calpain-1 activation contributes to cardiomyocyte apoptosis induced by hyperglycemia. This study was undertaken to investigate whether targeted disruption of calpain would reduce myocardial hypertrophy and fibrosis in mouse models of type 1 diabetes.

Research design and methods: Diabetes in mice was induced by injection of streptozotocin (STZ), and OVE26 mice were also used as a type 1 diabetic model. The function of calpain was genetically manipulated by cardiomyocyte-specific knockout Capn4 in mice and the use of calpastatin transgenic mice. Myocardial hypertrophy and fibrosis were investigated 2 and 5 months after STZ injection or in OVE26 diabetic mice at the age of 5 months. Cultured isolated adult mouse cardiac fibroblast cells were also investigated under high glucose conditions.

Results: Calpain activity, cardiomyocyte cross-sectional areas, and myocardial collagen deposition were significantly increased in both STZ-induced and OVE26 diabetic hearts, and these were accompanied by elevated expression of hypertrophic and fibrotic collagen genes. Deficiency of Capn4 or overexpression of calpastatin reduced myocardial hypertrophy and fibrosis in both diabetic models, leading to the improvement of myocardial function. These effects were associated with a normalization of the nuclear factor of activated T-cell nuclear factor-κB and matrix metalloproteinase (MMP) activities in diabetic hearts. In cultured cardiac fibroblasts, high glucose-induced proliferation and MMP activities were prevented by calpain inhibition.

Conclusions: Myocardial hypertrophy and fibrosis in diabetic mice are attenuated by reduction of calpain function. Thus targeted inhibition of calpain represents a potential novel therapeutic strategy for reversing diabetic cardiomyopathy.

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MMP activities and TIMP expression in diabetic hearts. MMP activities were determined in Capn4−/−, Tg-CAST, and OVE26 hearts. A: MMP activities were increased in diabetic hearts. Overexpression of calpastatin reduced total MMP activities and MMP-2 and MMP-9 activities in diabetic Tg-CAST hearts (A–C). D–F: Deficiency of Capn4 reduced total MMP activities and MMP-2 and MMP-9 activities in Capn4−/− (knockout [KO]) relative to nondiabetic wild-type (WT) hearts. G: Total MMP activities were elevated in OVE26 relative to WT hearts and were decreased in Tg-CAST/OVE26 hearts. H and I: TIMP-1 and TIMP-2 mRNA levels were decreased in Capn4−/− (KO) relative to nondiabetic WT hearts. Data are mean ± SD; n = 6–8. *P < 0.05 vs. WT; #P < 0.05 vs. STZ-treated WT or OVE26.
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Figure 6: MMP activities and TIMP expression in diabetic hearts. MMP activities were determined in Capn4−/−, Tg-CAST, and OVE26 hearts. A: MMP activities were increased in diabetic hearts. Overexpression of calpastatin reduced total MMP activities and MMP-2 and MMP-9 activities in diabetic Tg-CAST hearts (A–C). D–F: Deficiency of Capn4 reduced total MMP activities and MMP-2 and MMP-9 activities in Capn4−/− (knockout [KO]) relative to nondiabetic wild-type (WT) hearts. G: Total MMP activities were elevated in OVE26 relative to WT hearts and were decreased in Tg-CAST/OVE26 hearts. H and I: TIMP-1 and TIMP-2 mRNA levels were decreased in Capn4−/− (KO) relative to nondiabetic WT hearts. Data are mean ± SD; n = 6–8. *P < 0.05 vs. WT; #P < 0.05 vs. STZ-treated WT or OVE26.

Mentions: MMPs play key roles in maintenance and degradation of the extracellular matrix (ECM), contributing to the process of myocardial fibrosis (35), so we next measured MMP activity in the myocardium. STZ-induced diabetes correlated with 34% elevation in total MMP activity, but this increase was significantly reduced in diabetic Tg-CAST and Capn4−/− mice (Fig. 6A and D). Because MMP-2 and MMP-9 are the most important MMPs in the regulation of myocardial remodeling, we measured their activities in the diabetic heart. Similarly, both MMP-2 and MMP-9 activities were reduced in Tg-CAST and Capn4−/− mice (Fig. 6B, C, E, and F). The role of MMPs is negatively regulated by tissue inhibitors of metalloproteinases (TIMPs). We therefore also measured TIMP-1 and TIMP-2 expression in the diabetic heart. The mRNA levels of TIMP-1 and TIMP-2 were significantly increased in diabetic Capn4−/− compared with Capn+/+ mice (Fig. 6H and I). Taken together, our data suggest that disruption of calpain may inhibit MMP activities through downregulation of TIMP-1 and TIMP-2 in the diabetic heart.


Targeted inhibition of calpain reduces myocardial hypertrophy and fibrosis in mouse models of type 1 diabetes.

Li Y, Ma J, Zhu H, Singh M, Hill D, Greer PA, Arnold JM, Abel ED, Peng T - Diabetes (2011)

MMP activities and TIMP expression in diabetic hearts. MMP activities were determined in Capn4−/−, Tg-CAST, and OVE26 hearts. A: MMP activities were increased in diabetic hearts. Overexpression of calpastatin reduced total MMP activities and MMP-2 and MMP-9 activities in diabetic Tg-CAST hearts (A–C). D–F: Deficiency of Capn4 reduced total MMP activities and MMP-2 and MMP-9 activities in Capn4−/− (knockout [KO]) relative to nondiabetic wild-type (WT) hearts. G: Total MMP activities were elevated in OVE26 relative to WT hearts and were decreased in Tg-CAST/OVE26 hearts. H and I: TIMP-1 and TIMP-2 mRNA levels were decreased in Capn4−/− (KO) relative to nondiabetic WT hearts. Data are mean ± SD; n = 6–8. *P < 0.05 vs. WT; #P < 0.05 vs. STZ-treated WT or OVE26.
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Figure 6: MMP activities and TIMP expression in diabetic hearts. MMP activities were determined in Capn4−/−, Tg-CAST, and OVE26 hearts. A: MMP activities were increased in diabetic hearts. Overexpression of calpastatin reduced total MMP activities and MMP-2 and MMP-9 activities in diabetic Tg-CAST hearts (A–C). D–F: Deficiency of Capn4 reduced total MMP activities and MMP-2 and MMP-9 activities in Capn4−/− (knockout [KO]) relative to nondiabetic wild-type (WT) hearts. G: Total MMP activities were elevated in OVE26 relative to WT hearts and were decreased in Tg-CAST/OVE26 hearts. H and I: TIMP-1 and TIMP-2 mRNA levels were decreased in Capn4−/− (KO) relative to nondiabetic WT hearts. Data are mean ± SD; n = 6–8. *P < 0.05 vs. WT; #P < 0.05 vs. STZ-treated WT or OVE26.
Mentions: MMPs play key roles in maintenance and degradation of the extracellular matrix (ECM), contributing to the process of myocardial fibrosis (35), so we next measured MMP activity in the myocardium. STZ-induced diabetes correlated with 34% elevation in total MMP activity, but this increase was significantly reduced in diabetic Tg-CAST and Capn4−/− mice (Fig. 6A and D). Because MMP-2 and MMP-9 are the most important MMPs in the regulation of myocardial remodeling, we measured their activities in the diabetic heart. Similarly, both MMP-2 and MMP-9 activities were reduced in Tg-CAST and Capn4−/− mice (Fig. 6B, C, E, and F). The role of MMPs is negatively regulated by tissue inhibitors of metalloproteinases (TIMPs). We therefore also measured TIMP-1 and TIMP-2 expression in the diabetic heart. The mRNA levels of TIMP-1 and TIMP-2 were significantly increased in diabetic Capn4−/− compared with Capn+/+ mice (Fig. 6H and I). Taken together, our data suggest that disruption of calpain may inhibit MMP activities through downregulation of TIMP-1 and TIMP-2 in the diabetic heart.

Bottom Line: Calpain activity, cardiomyocyte cross-sectional areas, and myocardial collagen deposition were significantly increased in both STZ-induced and OVE26 diabetic hearts, and these were accompanied by elevated expression of hypertrophic and fibrotic collagen genes.These effects were associated with a normalization of the nuclear factor of activated T-cell nuclear factor-κB and matrix metalloproteinase (MMP) activities in diabetic hearts.Thus targeted inhibition of calpain represents a potential novel therapeutic strategy for reversing diabetic cardiomyopathy.

View Article: PubMed Central - PubMed

Affiliation: Critical Illness Research, Lawson Health Research Institute, University of Western Ontario, London, Ontario, Canada.

ABSTRACT

Objective: Recently we have shown that calpain-1 activation contributes to cardiomyocyte apoptosis induced by hyperglycemia. This study was undertaken to investigate whether targeted disruption of calpain would reduce myocardial hypertrophy and fibrosis in mouse models of type 1 diabetes.

Research design and methods: Diabetes in mice was induced by injection of streptozotocin (STZ), and OVE26 mice were also used as a type 1 diabetic model. The function of calpain was genetically manipulated by cardiomyocyte-specific knockout Capn4 in mice and the use of calpastatin transgenic mice. Myocardial hypertrophy and fibrosis were investigated 2 and 5 months after STZ injection or in OVE26 diabetic mice at the age of 5 months. Cultured isolated adult mouse cardiac fibroblast cells were also investigated under high glucose conditions.

Results: Calpain activity, cardiomyocyte cross-sectional areas, and myocardial collagen deposition were significantly increased in both STZ-induced and OVE26 diabetic hearts, and these were accompanied by elevated expression of hypertrophic and fibrotic collagen genes. Deficiency of Capn4 or overexpression of calpastatin reduced myocardial hypertrophy and fibrosis in both diabetic models, leading to the improvement of myocardial function. These effects were associated with a normalization of the nuclear factor of activated T-cell nuclear factor-κB and matrix metalloproteinase (MMP) activities in diabetic hearts. In cultured cardiac fibroblasts, high glucose-induced proliferation and MMP activities were prevented by calpain inhibition.

Conclusions: Myocardial hypertrophy and fibrosis in diabetic mice are attenuated by reduction of calpain function. Thus targeted inhibition of calpain represents a potential novel therapeutic strategy for reversing diabetic cardiomyopathy.

Show MeSH
Related in: MedlinePlus