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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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Related in: MedlinePlus

Assessment of cardiac hypertrophy in OVE26 mice. A–D: Cardiomyocyte cross-sectional areas, the mRNA levels of ANP (B) and β-MHC (C), and caspase-3 activity (D) increased in OVE26 relative to wild-type (WT) hearts, but were reduced in Tg-CAST/OVE26 mice. E–H: NFAT and NF-κB activities were increased in OVE26 and STZ-injected WT hearts but were reduced in Tg-CAST/OVE26 and Capn4 knockout (KO) hearts. Data are mean ± SD; n = 6–8. *P < 0.05 vs. WT; #P < 0.05 vs. OVE26 or STZ in WT.
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Figure 4: Assessment of cardiac hypertrophy in OVE26 mice. A–D: Cardiomyocyte cross-sectional areas, the mRNA levels of ANP (B) and β-MHC (C), and caspase-3 activity (D) increased in OVE26 relative to wild-type (WT) hearts, but were reduced in Tg-CAST/OVE26 mice. E–H: NFAT and NF-κB activities were increased in OVE26 and STZ-injected WT hearts but were reduced in Tg-CAST/OVE26 and Capn4 knockout (KO) hearts. Data are mean ± SD; n = 6–8. *P < 0.05 vs. WT; #P < 0.05 vs. OVE26 or STZ in WT.

Mentions: To rule out the possibility that STZ treatment had systemic actions independent of β-cell destruction, we repeated these experiments in the OVE26 type 1 diabetic mouse model and crossed them with Tg-CAST mice to inhibit calpain activity. Expression of transgenic calpastatin in the OVE26 heart was confirmed by RT-PCR (Supplementary Fig. 5A). At the age of 5 months, cardiomyocyte cross-sectional areas, the levels of ANP and β-MHC mRNA, and caspase-3 activity were significantly increased in OVE26 mice compared with their wild-type littermates (Fig. 4A–D), indicative of cardiac hypertrophy. There were no differences in blood glucose levels and body and heart weight between OVE26 and Tg-CAST/OVE26 mice (Supplementary Table 1); however, the increases in cardiomyocyte cross-sectional areas, ANP and β-MHC expression, and caspase-3 in OVE26 hearts were normalized in Tg-CAST/OVE26 mice (Fig. 4A–D). These results in the OVE26 model further support the antihypertrophic effect of calpain inhibition in type 1 diabetes.


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)

Assessment of cardiac hypertrophy in OVE26 mice. A–D: Cardiomyocyte cross-sectional areas, the mRNA levels of ANP (B) and β-MHC (C), and caspase-3 activity (D) increased in OVE26 relative to wild-type (WT) hearts, but were reduced in Tg-CAST/OVE26 mice. E–H: NFAT and NF-κB activities were increased in OVE26 and STZ-injected WT hearts but were reduced in Tg-CAST/OVE26 and Capn4 knockout (KO) hearts. Data are mean ± SD; n = 6–8. *P < 0.05 vs. WT; #P < 0.05 vs. OVE26 or STZ in WT.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3198063&req=5

Figure 4: Assessment of cardiac hypertrophy in OVE26 mice. A–D: Cardiomyocyte cross-sectional areas, the mRNA levels of ANP (B) and β-MHC (C), and caspase-3 activity (D) increased in OVE26 relative to wild-type (WT) hearts, but were reduced in Tg-CAST/OVE26 mice. E–H: NFAT and NF-κB activities were increased in OVE26 and STZ-injected WT hearts but were reduced in Tg-CAST/OVE26 and Capn4 knockout (KO) hearts. Data are mean ± SD; n = 6–8. *P < 0.05 vs. WT; #P < 0.05 vs. OVE26 or STZ in WT.
Mentions: To rule out the possibility that STZ treatment had systemic actions independent of β-cell destruction, we repeated these experiments in the OVE26 type 1 diabetic mouse model and crossed them with Tg-CAST mice to inhibit calpain activity. Expression of transgenic calpastatin in the OVE26 heart was confirmed by RT-PCR (Supplementary Fig. 5A). At the age of 5 months, cardiomyocyte cross-sectional areas, the levels of ANP and β-MHC mRNA, and caspase-3 activity were significantly increased in OVE26 mice compared with their wild-type littermates (Fig. 4A–D), indicative of cardiac hypertrophy. There were no differences in blood glucose levels and body and heart weight between OVE26 and Tg-CAST/OVE26 mice (Supplementary Table 1); however, the increases in cardiomyocyte cross-sectional areas, ANP and β-MHC expression, and caspase-3 in OVE26 hearts were normalized in Tg-CAST/OVE26 mice (Fig. 4A–D). These results in the OVE26 model further support the antihypertrophic effect of calpain inhibition in type 1 diabetes.

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