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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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Assessment of fibrosis in diabetic hearts. Myocardial collagen deposition was determined by picrosirius red staining and collagen III mRNA was quantified by real-time RT-PCR. A: Representative picrosirius red staining for collagen deposition from diabetic Capn4−/− and Capn4+/+ hearts (red color). Collagen deposition was reduced in hearts of Capn4−/− (knockout [KO]; B), Tg-CAST (C), and Tg-CAST/OVE26 (D) relative to diabetic wild-type (WT), Capn4+/+ (KO), and OVE26 diabetic mice, respectively. Collagen III mRNA was decreased in diabetic Capn4−/− (E), Tg-CAST (F), and Tg-CAST/OVE26 mice (G). Data are mean ± SD; n = 8 to 9. *P < 0.05 vs. sham or nondiabetic WT; #P < 0.05 vs. STZ in WT or OVE26. (A high-quality color representation of this figure is available in the online issue.)
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Figure 5: Assessment of fibrosis in diabetic hearts. Myocardial collagen deposition was determined by picrosirius red staining and collagen III mRNA was quantified by real-time RT-PCR. A: Representative picrosirius red staining for collagen deposition from diabetic Capn4−/− and Capn4+/+ hearts (red color). Collagen deposition was reduced in hearts of Capn4−/− (knockout [KO]; B), Tg-CAST (C), and Tg-CAST/OVE26 (D) relative to diabetic wild-type (WT), Capn4+/+ (KO), and OVE26 diabetic mice, respectively. Collagen III mRNA was decreased in diabetic Capn4−/− (E), Tg-CAST (F), and Tg-CAST/OVE26 mice (G). Data are mean ± SD; n = 8 to 9. *P < 0.05 vs. sham or nondiabetic WT; #P < 0.05 vs. STZ in WT or OVE26. (A high-quality color representation of this figure is available in the online issue.)

Mentions: Myocardial fibrosis is commonly observed in diabetic cardiomyopathy and is characterized by excessive production and accumulation of extracellular collagen (1,34). To assess fibrosis, myocardial tissues were stained with picrosirius red to highlight collagen. Ratios of collagen area to total area were measured. Deposition of collagen was increased in STZ-induced diabetic hearts; however, Capn4 deletion in Capn4−/− mice and calpastatin overexpression in Tg-CAST mice correlated with a significant reduction in those levels after STZ injection (Fig. 5A–C). In line with altered collagen deposition, deletion of Capn4 and overexpression of calpastatin lowered the mRNA levels of collagens I and III in diabetic Capn4−/− and Tg-CAST hearts, respectively (Fig. 5E and F and Supplementary Fig. 6A). Similarly, this inhibitory effect of calpain deletion on myocardial fibrosis was also observed 5 months after STZ injection (Supplementary Fig. 4C–E). Thus, inhibition or targeted disruption of calpain prevented myocardial fibrosis in the STZ-induced mouse model of 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 fibrosis in diabetic hearts. Myocardial collagen deposition was determined by picrosirius red staining and collagen III mRNA was quantified by real-time RT-PCR. A: Representative picrosirius red staining for collagen deposition from diabetic Capn4−/− and Capn4+/+ hearts (red color). Collagen deposition was reduced in hearts of Capn4−/− (knockout [KO]; B), Tg-CAST (C), and Tg-CAST/OVE26 (D) relative to diabetic wild-type (WT), Capn4+/+ (KO), and OVE26 diabetic mice, respectively. Collagen III mRNA was decreased in diabetic Capn4−/− (E), Tg-CAST (F), and Tg-CAST/OVE26 mice (G). Data are mean ± SD; n = 8 to 9. *P < 0.05 vs. sham or nondiabetic WT; #P < 0.05 vs. STZ in WT or OVE26. (A high-quality color representation of this figure is available in the online issue.)
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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

Figure 5: Assessment of fibrosis in diabetic hearts. Myocardial collagen deposition was determined by picrosirius red staining and collagen III mRNA was quantified by real-time RT-PCR. A: Representative picrosirius red staining for collagen deposition from diabetic Capn4−/− and Capn4+/+ hearts (red color). Collagen deposition was reduced in hearts of Capn4−/− (knockout [KO]; B), Tg-CAST (C), and Tg-CAST/OVE26 (D) relative to diabetic wild-type (WT), Capn4+/+ (KO), and OVE26 diabetic mice, respectively. Collagen III mRNA was decreased in diabetic Capn4−/− (E), Tg-CAST (F), and Tg-CAST/OVE26 mice (G). Data are mean ± SD; n = 8 to 9. *P < 0.05 vs. sham or nondiabetic WT; #P < 0.05 vs. STZ in WT or OVE26. (A high-quality color representation of this figure is available in the online issue.)
Mentions: Myocardial fibrosis is commonly observed in diabetic cardiomyopathy and is characterized by excessive production and accumulation of extracellular collagen (1,34). To assess fibrosis, myocardial tissues were stained with picrosirius red to highlight collagen. Ratios of collagen area to total area were measured. Deposition of collagen was increased in STZ-induced diabetic hearts; however, Capn4 deletion in Capn4−/− mice and calpastatin overexpression in Tg-CAST mice correlated with a significant reduction in those levels after STZ injection (Fig. 5A–C). In line with altered collagen deposition, deletion of Capn4 and overexpression of calpastatin lowered the mRNA levels of collagens I and III in diabetic Capn4−/− and Tg-CAST hearts, respectively (Fig. 5E and F and Supplementary Fig. 6A). Similarly, this inhibitory effect of calpain deletion on myocardial fibrosis was also observed 5 months after STZ injection (Supplementary Fig. 4C–E). Thus, inhibition or targeted disruption of calpain prevented myocardial fibrosis in the STZ-induced mouse model of 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