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The Early-Onset Myocardial Infarction Associated PHACTR1 Gene Regulates Skeletal and Cardiac Alpha-Actin Gene Expression.

Kelloniemi A, Szabo Z, Serpi R, Näpänkangas J, Ohukainen P, Tenhunen O, Kaikkonen L, Koivisto E, Bagyura Z, Kerkelä R, Leosdottir M, Hedner T, Melander O, Ruskoaho H, Rysä J - PLoS ONE (2015)

Bottom Line: We characterized the mechanisms regulating Phactr1 expression in the heart, used adenoviral gene delivery to investigate the effects of Phactr1 on cardiac function, and analyzed the relationship between MI associated PHACTR1 allele and cardiac function in human subjects.When the direct myocardial effects of Phactr1 were studied, the skeletal α-actin to cardiac α-actin isoform ratio was significantly higher (1.5-fold, P<0.05) at 3 days but 40% lower (P<0.05) at 2 weeks after adenovirus-mediated Phactr1 gene delivery into the anterior wall of the left ventricle.In human subjects, MI associated PHACTR1 allele was not associated significantly with cardiac function (n = 1550).

View Article: PubMed Central - PubMed

Affiliation: Institute of Biomedicine, Department of Pharmacology and Toxicology, University of Oulu, Oulu, Finland.

ABSTRACT
The phosphatase and actin regulator 1 (PHACTR1) locus is a very commonly identified hit in genome-wide association studies investigating coronary artery disease and myocardial infarction (MI). However, the function of PHACTR1 in the heart is still unknown. We characterized the mechanisms regulating Phactr1 expression in the heart, used adenoviral gene delivery to investigate the effects of Phactr1 on cardiac function, and analyzed the relationship between MI associated PHACTR1 allele and cardiac function in human subjects. Phactr1 mRNA and protein levels were markedly reduced (60%, P<0.01 and 90%, P<0.001, respectively) at 1 day after MI in rats. When the direct myocardial effects of Phactr1 were studied, the skeletal α-actin to cardiac α-actin isoform ratio was significantly higher (1.5-fold, P<0.05) at 3 days but 40% lower (P<0.05) at 2 weeks after adenovirus-mediated Phactr1 gene delivery into the anterior wall of the left ventricle. Similarly, the skeletal α-actin to cardiac α-actin ratio was lower at 2 weeks in infarcted hearts overexpressing Phactr1. In cultured neonatal cardiac myocytes, adenovirus-mediated Phactr1 overexpression for 48 hours markedly increased the skeletal α-actin to cardiac α-actin ratio, this being associated with an enhanced DNA binding activity of serum response factor. Phactr1 overexpression exerted no major effects on the expression of other cardiac genes or LV structure and function in normal and infarcted hearts during 2 weeks' follow-up period. In human subjects, MI associated PHACTR1 allele was not associated significantly with cardiac function (n = 1550). Phactr1 seems to regulate the skeletal to cardiac α-actin isoform ratio.

No MeSH data available.


Related in: MedlinePlus

Effects of Phactr1 gene delivery post-infarction in adult rats.A) Phactr1 mRNA levels measured by RT-PCR and B) Phactr1 total protein levels analyzed by Western blot analyses from the LV tissue samples 1 day, 1 week and 2 weeks after Phactr1 gene delivery and MI. C) Skeletal α-actin (skα-A) and cardiac α-actin (caα-A) mRNA levels measured by RT-PCR and skα-A to caα-A ratio, and D) β-myosin heavy chain (β-MHC) and α-myosin heavy chain (α-MHC) mRNA levels and β-MHC to α-MHC ratio at 2 weeks after Phactr1 gene transfer and MI. Open bars represent LacZ with MI and solid bars Phactr1 with MI (n = 5–11). *P< 0.05, **P<0.01, ***P<0.001 versus LacZ with MI (Student’s t-test). E and F) Fibrotic area and number of TUNEL+ cells at 1 week after gene transfer and MI (n = 7–9). The results are expressed as mean±SEM. Representative Western blots are shown.
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pone.0130502.g007: Effects of Phactr1 gene delivery post-infarction in adult rats.A) Phactr1 mRNA levels measured by RT-PCR and B) Phactr1 total protein levels analyzed by Western blot analyses from the LV tissue samples 1 day, 1 week and 2 weeks after Phactr1 gene delivery and MI. C) Skeletal α-actin (skα-A) and cardiac α-actin (caα-A) mRNA levels measured by RT-PCR and skα-A to caα-A ratio, and D) β-myosin heavy chain (β-MHC) and α-myosin heavy chain (α-MHC) mRNA levels and β-MHC to α-MHC ratio at 2 weeks after Phactr1 gene transfer and MI. Open bars represent LacZ with MI and solid bars Phactr1 with MI (n = 5–11). *P< 0.05, **P<0.01, ***P<0.001 versus LacZ with MI (Student’s t-test). E and F) Fibrotic area and number of TUNEL+ cells at 1 week after gene transfer and MI (n = 7–9). The results are expressed as mean±SEM. Representative Western blots are shown.

Mentions: Since Phactr1 expression was markedly down-regulated after MI, we next studied the effects of Phactr1 overexpression on cardiac gene expression, function and structure in an experimental rat MI model. RT-PCR and Western blot analysis revealed a significant increase in Phactr1 mRNA and protein levels, respectively, by adenovirus-mediated overexpression of Phactr1 up to 2 weeks after MI (Fig 7A and 7B). Consistently with the results observed in normal hearts, the skeletal to cardiac α-actin ratio was statistically significantly reduced at 2 weeks after MI (50%; P<0.05) (Fig 7C). Moreover, there were no statistically significant differences in the β-myosin heavy chain to α-myosin heavy chain ratio (Fig 7D) and in mRNA levels of ANP, BNP, Serca2 and PLB between LacZ- and Phactr1-treated groups (Fig 8A) 2 weeks after MI. In addition, Serca2 and PLB protein levels in Phactr1-treated group were similar to those of LacZ-treated group after MI (Fig 8B and 8C). Phactr1 gene delivery after MI did not influence the extent of fibrosis or the number of apoptotic cells (Fig 7E and 7F). There was a tendency for higher LV EF and FS in Phactr1-treated animals after MI when compared to LacZ-treated group but these changes were not statistically significant (Fig 6F and 6G). LV dimensions did not differ between Phactr1-treated hearts and LacZ-treated hearts after MI (Fig 6H and 6I).


The Early-Onset Myocardial Infarction Associated PHACTR1 Gene Regulates Skeletal and Cardiac Alpha-Actin Gene Expression.

Kelloniemi A, Szabo Z, Serpi R, Näpänkangas J, Ohukainen P, Tenhunen O, Kaikkonen L, Koivisto E, Bagyura Z, Kerkelä R, Leosdottir M, Hedner T, Melander O, Ruskoaho H, Rysä J - PLoS ONE (2015)

Effects of Phactr1 gene delivery post-infarction in adult rats.A) Phactr1 mRNA levels measured by RT-PCR and B) Phactr1 total protein levels analyzed by Western blot analyses from the LV tissue samples 1 day, 1 week and 2 weeks after Phactr1 gene delivery and MI. C) Skeletal α-actin (skα-A) and cardiac α-actin (caα-A) mRNA levels measured by RT-PCR and skα-A to caα-A ratio, and D) β-myosin heavy chain (β-MHC) and α-myosin heavy chain (α-MHC) mRNA levels and β-MHC to α-MHC ratio at 2 weeks after Phactr1 gene transfer and MI. Open bars represent LacZ with MI and solid bars Phactr1 with MI (n = 5–11). *P< 0.05, **P<0.01, ***P<0.001 versus LacZ with MI (Student’s t-test). E and F) Fibrotic area and number of TUNEL+ cells at 1 week after gene transfer and MI (n = 7–9). The results are expressed as mean±SEM. Representative Western blots are shown.
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Related In: Results  -  Collection

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pone.0130502.g007: Effects of Phactr1 gene delivery post-infarction in adult rats.A) Phactr1 mRNA levels measured by RT-PCR and B) Phactr1 total protein levels analyzed by Western blot analyses from the LV tissue samples 1 day, 1 week and 2 weeks after Phactr1 gene delivery and MI. C) Skeletal α-actin (skα-A) and cardiac α-actin (caα-A) mRNA levels measured by RT-PCR and skα-A to caα-A ratio, and D) β-myosin heavy chain (β-MHC) and α-myosin heavy chain (α-MHC) mRNA levels and β-MHC to α-MHC ratio at 2 weeks after Phactr1 gene transfer and MI. Open bars represent LacZ with MI and solid bars Phactr1 with MI (n = 5–11). *P< 0.05, **P<0.01, ***P<0.001 versus LacZ with MI (Student’s t-test). E and F) Fibrotic area and number of TUNEL+ cells at 1 week after gene transfer and MI (n = 7–9). The results are expressed as mean±SEM. Representative Western blots are shown.
Mentions: Since Phactr1 expression was markedly down-regulated after MI, we next studied the effects of Phactr1 overexpression on cardiac gene expression, function and structure in an experimental rat MI model. RT-PCR and Western blot analysis revealed a significant increase in Phactr1 mRNA and protein levels, respectively, by adenovirus-mediated overexpression of Phactr1 up to 2 weeks after MI (Fig 7A and 7B). Consistently with the results observed in normal hearts, the skeletal to cardiac α-actin ratio was statistically significantly reduced at 2 weeks after MI (50%; P<0.05) (Fig 7C). Moreover, there were no statistically significant differences in the β-myosin heavy chain to α-myosin heavy chain ratio (Fig 7D) and in mRNA levels of ANP, BNP, Serca2 and PLB between LacZ- and Phactr1-treated groups (Fig 8A) 2 weeks after MI. In addition, Serca2 and PLB protein levels in Phactr1-treated group were similar to those of LacZ-treated group after MI (Fig 8B and 8C). Phactr1 gene delivery after MI did not influence the extent of fibrosis or the number of apoptotic cells (Fig 7E and 7F). There was a tendency for higher LV EF and FS in Phactr1-treated animals after MI when compared to LacZ-treated group but these changes were not statistically significant (Fig 6F and 6G). LV dimensions did not differ between Phactr1-treated hearts and LacZ-treated hearts after MI (Fig 6H and 6I).

Bottom Line: We characterized the mechanisms regulating Phactr1 expression in the heart, used adenoviral gene delivery to investigate the effects of Phactr1 on cardiac function, and analyzed the relationship between MI associated PHACTR1 allele and cardiac function in human subjects.When the direct myocardial effects of Phactr1 were studied, the skeletal α-actin to cardiac α-actin isoform ratio was significantly higher (1.5-fold, P<0.05) at 3 days but 40% lower (P<0.05) at 2 weeks after adenovirus-mediated Phactr1 gene delivery into the anterior wall of the left ventricle.In human subjects, MI associated PHACTR1 allele was not associated significantly with cardiac function (n = 1550).

View Article: PubMed Central - PubMed

Affiliation: Institute of Biomedicine, Department of Pharmacology and Toxicology, University of Oulu, Oulu, Finland.

ABSTRACT
The phosphatase and actin regulator 1 (PHACTR1) locus is a very commonly identified hit in genome-wide association studies investigating coronary artery disease and myocardial infarction (MI). However, the function of PHACTR1 in the heart is still unknown. We characterized the mechanisms regulating Phactr1 expression in the heart, used adenoviral gene delivery to investigate the effects of Phactr1 on cardiac function, and analyzed the relationship between MI associated PHACTR1 allele and cardiac function in human subjects. Phactr1 mRNA and protein levels were markedly reduced (60%, P<0.01 and 90%, P<0.001, respectively) at 1 day after MI in rats. When the direct myocardial effects of Phactr1 were studied, the skeletal α-actin to cardiac α-actin isoform ratio was significantly higher (1.5-fold, P<0.05) at 3 days but 40% lower (P<0.05) at 2 weeks after adenovirus-mediated Phactr1 gene delivery into the anterior wall of the left ventricle. Similarly, the skeletal α-actin to cardiac α-actin ratio was lower at 2 weeks in infarcted hearts overexpressing Phactr1. In cultured neonatal cardiac myocytes, adenovirus-mediated Phactr1 overexpression for 48 hours markedly increased the skeletal α-actin to cardiac α-actin ratio, this being associated with an enhanced DNA binding activity of serum response factor. Phactr1 overexpression exerted no major effects on the expression of other cardiac genes or LV structure and function in normal and infarcted hearts during 2 weeks' follow-up period. In human subjects, MI associated PHACTR1 allele was not associated significantly with cardiac function (n = 1550). Phactr1 seems to regulate the skeletal to cardiac α-actin isoform ratio.

No MeSH data available.


Related in: MedlinePlus