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Profilin modulates sarcomeric organization and mediates cardiomyocyte hypertrophy.

Kooij V, Viswanathan MC, Lee DI, Rainer PP, Schmidt W, Kronert WA, Harding SE, Kass DA, Bernstein SI, Van Eyk JE, Cammarato A - Cardiovasc. Res. (2016)

Bottom Line: Mechanistically, we found that profilin-1 regulates hypertrophy, in part, through activation of the ERK1/2 signalling cascade.Elevated profilin levels resulted in elongated sarcomeres, myofibrillar disorganization, and sarcomeric disarray, which correlated with impaired muscle function.Our results identify novel roles for profilin as an important mediator of cardiomyocyte hypertrophy.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Division of Cardiology, The Johns Hopkins University, Baltimore, MD, USA National Heart and Lung Institute, Imperial College London, 4th floor, ICTEM, Hammersmith Campus, Du Cane Road, London W12 0NN, UK v.kooij@imperial.ac.uk.

No MeSH data available.


Related in: MedlinePlus

Elongated thin filaments and sarcomeres in flies overexpressing profilin. (A) Left: increased IFM thin filament (n = 252–255, ***P < 0.001; one-way ANOVA with the Bonferroni post hoc test) and sarcomere lengths (n = 106–116, ***P < 0.001; one-way ANOVA with the Bonferroni post hoc test) were measured in flies with Mef2-GAL4-driven profilin overexpression. Right: typical IFM sarcomeres for control and profilin-overexpressing flies (red, TRITC-phalloidin-stained thin filaments; yellow, anti-α-actinin-stained Z-lines). (B) Averaged composite images of consecutive IFM sarcomeres from flies with elevated profilin levels revealed localization at the Z-line and at the thin filament pointed end/H-zone, whereas controls predominantly showed profilin localization at the Z-line. The M-line/H-zone was labelled using an MHC antibody that recognizes the centre of thick filaments along IFM myofibrils. (C) Based on normalized fluorescence intensity, Mef2 > Pfn_1 and Mef2 > Pfn_2 transgenic flies had significantly more profilin at the M-lines/H-zones, proximal to the thin filament pointed ends, relative to that at the Z-lines compared with controls (n = 123–143, ***P < 0.001; one-way ANOVA with the Bonferroni post hoc test).
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CVW050F4: Elongated thin filaments and sarcomeres in flies overexpressing profilin. (A) Left: increased IFM thin filament (n = 252–255, ***P < 0.001; one-way ANOVA with the Bonferroni post hoc test) and sarcomere lengths (n = 106–116, ***P < 0.001; one-way ANOVA with the Bonferroni post hoc test) were measured in flies with Mef2-GAL4-driven profilin overexpression. Right: typical IFM sarcomeres for control and profilin-overexpressing flies (red, TRITC-phalloidin-stained thin filaments; yellow, anti-α-actinin-stained Z-lines). (B) Averaged composite images of consecutive IFM sarcomeres from flies with elevated profilin levels revealed localization at the Z-line and at the thin filament pointed end/H-zone, whereas controls predominantly showed profilin localization at the Z-line. The M-line/H-zone was labelled using an MHC antibody that recognizes the centre of thick filaments along IFM myofibrils. (C) Based on normalized fluorescence intensity, Mef2 > Pfn_1 and Mef2 > Pfn_2 transgenic flies had significantly more profilin at the M-lines/H-zones, proximal to the thin filament pointed ends, relative to that at the Z-lines compared with controls (n = 123–143, ***P < 0.001; one-way ANOVA with the Bonferroni post hoc test).

Mentions: To verify an effect of muscle-restricted profilin overexpression on thin filament and sarcomere lengths, Drosophila IFM myofibrils were labelled with anti-α-actinin antibody, a Z-line protein, and TRITC-phalloidin, imaged via confocal microscopy, and dimensions ascertained (see Supplementary material online, Figure S3A). Increased expression of profilin via the Mef2-GAL4 driver (Figure 3A) resulted in significantly elongated thin filament (Mef2 > Pfn_1 1.42 ± 0.01 μm, n = 255; Mef2 > Pfn_2 1.41 ± 0.01 μm, n = 252) and sarcomere lengths (Mef2 > Pfn_1 3.57 ± 0.01 μm, n = 106; Mef2 > Pfn_2 3.59 ± 0.01 μm, n = 116) compared with control thin filament (1.25 ± 0.01 μm, n = 255) and sarcomere lengths (3.29 ± 0.01 μm, n = 114; Figure 4A). These results are consistent with significantly increased sarcomere lengths measured from electron micrographs (Figure 3D) and were confirmed in flies overexpressing profilin in the IFM using the UH3-GAL4 driver line (thin filament: control 1.28 ± 0.01 μm, n = 274; UH3 > Pfn_1 1.46 ± 0.01 μm, n = 274; UH3 > Pfn_2 1.42 ± 0.01 μm, n = 271; sarcomere lengths: control 3.31 ± 0.01 μm, n = 274; UH3 > Pfn_1 3.61 ± 0.01 μm, n = 98; UH3 > Pfn_2 3.63 ± 0.01 μm, n = 104; see Supplementary material online, Figure S3B).Figure 4


Profilin modulates sarcomeric organization and mediates cardiomyocyte hypertrophy.

Kooij V, Viswanathan MC, Lee DI, Rainer PP, Schmidt W, Kronert WA, Harding SE, Kass DA, Bernstein SI, Van Eyk JE, Cammarato A - Cardiovasc. Res. (2016)

Elongated thin filaments and sarcomeres in flies overexpressing profilin. (A) Left: increased IFM thin filament (n = 252–255, ***P < 0.001; one-way ANOVA with the Bonferroni post hoc test) and sarcomere lengths (n = 106–116, ***P < 0.001; one-way ANOVA with the Bonferroni post hoc test) were measured in flies with Mef2-GAL4-driven profilin overexpression. Right: typical IFM sarcomeres for control and profilin-overexpressing flies (red, TRITC-phalloidin-stained thin filaments; yellow, anti-α-actinin-stained Z-lines). (B) Averaged composite images of consecutive IFM sarcomeres from flies with elevated profilin levels revealed localization at the Z-line and at the thin filament pointed end/H-zone, whereas controls predominantly showed profilin localization at the Z-line. The M-line/H-zone was labelled using an MHC antibody that recognizes the centre of thick filaments along IFM myofibrils. (C) Based on normalized fluorescence intensity, Mef2 > Pfn_1 and Mef2 > Pfn_2 transgenic flies had significantly more profilin at the M-lines/H-zones, proximal to the thin filament pointed ends, relative to that at the Z-lines compared with controls (n = 123–143, ***P < 0.001; one-way ANOVA with the Bonferroni post hoc test).
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CVW050F4: Elongated thin filaments and sarcomeres in flies overexpressing profilin. (A) Left: increased IFM thin filament (n = 252–255, ***P < 0.001; one-way ANOVA with the Bonferroni post hoc test) and sarcomere lengths (n = 106–116, ***P < 0.001; one-way ANOVA with the Bonferroni post hoc test) were measured in flies with Mef2-GAL4-driven profilin overexpression. Right: typical IFM sarcomeres for control and profilin-overexpressing flies (red, TRITC-phalloidin-stained thin filaments; yellow, anti-α-actinin-stained Z-lines). (B) Averaged composite images of consecutive IFM sarcomeres from flies with elevated profilin levels revealed localization at the Z-line and at the thin filament pointed end/H-zone, whereas controls predominantly showed profilin localization at the Z-line. The M-line/H-zone was labelled using an MHC antibody that recognizes the centre of thick filaments along IFM myofibrils. (C) Based on normalized fluorescence intensity, Mef2 > Pfn_1 and Mef2 > Pfn_2 transgenic flies had significantly more profilin at the M-lines/H-zones, proximal to the thin filament pointed ends, relative to that at the Z-lines compared with controls (n = 123–143, ***P < 0.001; one-way ANOVA with the Bonferroni post hoc test).
Mentions: To verify an effect of muscle-restricted profilin overexpression on thin filament and sarcomere lengths, Drosophila IFM myofibrils were labelled with anti-α-actinin antibody, a Z-line protein, and TRITC-phalloidin, imaged via confocal microscopy, and dimensions ascertained (see Supplementary material online, Figure S3A). Increased expression of profilin via the Mef2-GAL4 driver (Figure 3A) resulted in significantly elongated thin filament (Mef2 > Pfn_1 1.42 ± 0.01 μm, n = 255; Mef2 > Pfn_2 1.41 ± 0.01 μm, n = 252) and sarcomere lengths (Mef2 > Pfn_1 3.57 ± 0.01 μm, n = 106; Mef2 > Pfn_2 3.59 ± 0.01 μm, n = 116) compared with control thin filament (1.25 ± 0.01 μm, n = 255) and sarcomere lengths (3.29 ± 0.01 μm, n = 114; Figure 4A). These results are consistent with significantly increased sarcomere lengths measured from electron micrographs (Figure 3D) and were confirmed in flies overexpressing profilin in the IFM using the UH3-GAL4 driver line (thin filament: control 1.28 ± 0.01 μm, n = 274; UH3 > Pfn_1 1.46 ± 0.01 μm, n = 274; UH3 > Pfn_2 1.42 ± 0.01 μm, n = 271; sarcomere lengths: control 3.31 ± 0.01 μm, n = 274; UH3 > Pfn_1 3.61 ± 0.01 μm, n = 98; UH3 > Pfn_2 3.63 ± 0.01 μm, n = 104; see Supplementary material online, Figure S3B).Figure 4

Bottom Line: Mechanistically, we found that profilin-1 regulates hypertrophy, in part, through activation of the ERK1/2 signalling cascade.Elevated profilin levels resulted in elongated sarcomeres, myofibrillar disorganization, and sarcomeric disarray, which correlated with impaired muscle function.Our results identify novel roles for profilin as an important mediator of cardiomyocyte hypertrophy.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Division of Cardiology, The Johns Hopkins University, Baltimore, MD, USA National Heart and Lung Institute, Imperial College London, 4th floor, ICTEM, Hammersmith Campus, Du Cane Road, London W12 0NN, UK v.kooij@imperial.ac.uk.

No MeSH data available.


Related in: MedlinePlus