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Systematic analysis of gene expression differences between left and right atria in different mouse strains and in human atrial tissue.

Kahr PC, Piccini I, Fabritz L, Greber B, Schöler H, Scheld HH, Hoffmeier A, Brown NA, Kirchhof P - PLoS ONE (2011)

Bottom Line: Normal development of the atria requires left-right differentiation during embryonic development.These differences were validated by RT-qPCR in murine and human tissue.Western blot showed a 2-fold left-right concentration gradient in PITX2 protein in adult human atria.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiology and Angiology, University Hospital Münster, Münster, Germany.

ABSTRACT

Background: Normal development of the atria requires left-right differentiation during embryonic development. Reduced expression of Pitx2c (paired-like homeodomain transcription factor 2, isoform c), a key regulator of left-right asymmetry, has recently been linked to atrial fibrillation. We therefore systematically studied the molecular composition of left and right atrial tissue in adult murine and human atria.

Methods: We compared left and right atrial gene expression in healthy, adult mice of different strains and ages by employing whole genome array analyses on freshly frozen atrial tissue. Selected genes with enriched expression in either atrium were validated by RT-qPCR and Western blot in further animals and in shock-frozen left and right atrial appendages of patients undergoing open heart surgery.

Results: We identified 77 genes with preferential expression in one atrium that were common in all strains and age groups analysed. Independent of strain and age, Pitx2c was the gene with the highest enrichment in left atrium, while Bmp10, a member of the TGFβ family, showed highest enrichment in right atrium. These differences were validated by RT-qPCR in murine and human tissue. Western blot showed a 2-fold left-right concentration gradient in PITX2 protein in adult human atria. Several of the genes and gene groups enriched in left atria have a known biological role for maintenance of healthy physiology, specifically the prevention of atrial pathologies involved in atrial fibrillation, including membrane electrophysiology, metabolic cellular function, and regulation of inflammatory processes. Comparison of the array datasets with published array analyses in heterozygous Pitx2c(+/-) atria suggested that approximately half of the genes with left-sided enrichment are regulated by Pitx2c.

Conclusions: Our study reveals systematic differences between left and right atrial gene expression and supports the hypothesis that Pitx2c has a functional role in maintaining "leftness" in the atrium in adult murine and human hearts.

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A) RT-qPCR measurements of orthologous transcripts in left atrial (black) and right atrial (white) human appendages (n = 5).Actb was used as control. Error bars indicate standard error of the mean (SEM). Statistically significant differences as assessed by paired Student's t-test are represented by asterisks (*P<0.05). B) and C) PITX2, IRX3, and BMP10 protein expression level measured by Western blot of total protein lysates from human left (black) and right (white) atrial appendages (n = 4). The data shown are averages of the results obtained from four separate samples. Error bars indicate standard deviation (SD). Statistically significant differences as assessed by unpaired Student's t-test are represented by asterisks (*P<0.05).
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pone-0026389-g004: A) RT-qPCR measurements of orthologous transcripts in left atrial (black) and right atrial (white) human appendages (n = 5).Actb was used as control. Error bars indicate standard error of the mean (SEM). Statistically significant differences as assessed by paired Student's t-test are represented by asterisks (*P<0.05). B) and C) PITX2, IRX3, and BMP10 protein expression level measured by Western blot of total protein lysates from human left (black) and right (white) atrial appendages (n = 4). The data shown are averages of the results obtained from four separate samples. Error bars indicate standard deviation (SD). Statistically significant differences as assessed by unpaired Student's t-test are represented by asterisks (*P<0.05).

Mentions: To determine whether the differences identified in the left and right atrial gene expression in the mouse are consistent in humans, we performed RT-qPCR measurements on human left and right atrial appendages (n = 5) harvested from patients undergoing open heart surgery. Clinical characteristics are given in Table 3. The RT-qPCR measurements confirmed differential expression in the left and right atrium in 5 of 9 tested human orthologues (Fig. 4A). Adm, Irx3, Kcn4, and Bmp10 were confirmed to be expressed at higher levels in right than in left atrium, whereas Pitx2c was enriched in left atrium, as expected. The murine left atrium-enriched genes Mapk10, Ppp1r1b, and Scn4b, and Ryr3, enriched in right atrium by array analysis, were not confirmed as such in the human tissue samples used for analysis.


Systematic analysis of gene expression differences between left and right atria in different mouse strains and in human atrial tissue.

Kahr PC, Piccini I, Fabritz L, Greber B, Schöler H, Scheld HH, Hoffmeier A, Brown NA, Kirchhof P - PLoS ONE (2011)

A) RT-qPCR measurements of orthologous transcripts in left atrial (black) and right atrial (white) human appendages (n = 5).Actb was used as control. Error bars indicate standard error of the mean (SEM). Statistically significant differences as assessed by paired Student's t-test are represented by asterisks (*P<0.05). B) and C) PITX2, IRX3, and BMP10 protein expression level measured by Western blot of total protein lysates from human left (black) and right (white) atrial appendages (n = 4). The data shown are averages of the results obtained from four separate samples. Error bars indicate standard deviation (SD). Statistically significant differences as assessed by unpaired Student's t-test are represented by asterisks (*P<0.05).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3198471&req=5

pone-0026389-g004: A) RT-qPCR measurements of orthologous transcripts in left atrial (black) and right atrial (white) human appendages (n = 5).Actb was used as control. Error bars indicate standard error of the mean (SEM). Statistically significant differences as assessed by paired Student's t-test are represented by asterisks (*P<0.05). B) and C) PITX2, IRX3, and BMP10 protein expression level measured by Western blot of total protein lysates from human left (black) and right (white) atrial appendages (n = 4). The data shown are averages of the results obtained from four separate samples. Error bars indicate standard deviation (SD). Statistically significant differences as assessed by unpaired Student's t-test are represented by asterisks (*P<0.05).
Mentions: To determine whether the differences identified in the left and right atrial gene expression in the mouse are consistent in humans, we performed RT-qPCR measurements on human left and right atrial appendages (n = 5) harvested from patients undergoing open heart surgery. Clinical characteristics are given in Table 3. The RT-qPCR measurements confirmed differential expression in the left and right atrium in 5 of 9 tested human orthologues (Fig. 4A). Adm, Irx3, Kcn4, and Bmp10 were confirmed to be expressed at higher levels in right than in left atrium, whereas Pitx2c was enriched in left atrium, as expected. The murine left atrium-enriched genes Mapk10, Ppp1r1b, and Scn4b, and Ryr3, enriched in right atrium by array analysis, were not confirmed as such in the human tissue samples used for analysis.

Bottom Line: Normal development of the atria requires left-right differentiation during embryonic development.These differences were validated by RT-qPCR in murine and human tissue.Western blot showed a 2-fold left-right concentration gradient in PITX2 protein in adult human atria.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiology and Angiology, University Hospital Münster, Münster, Germany.

ABSTRACT

Background: Normal development of the atria requires left-right differentiation during embryonic development. Reduced expression of Pitx2c (paired-like homeodomain transcription factor 2, isoform c), a key regulator of left-right asymmetry, has recently been linked to atrial fibrillation. We therefore systematically studied the molecular composition of left and right atrial tissue in adult murine and human atria.

Methods: We compared left and right atrial gene expression in healthy, adult mice of different strains and ages by employing whole genome array analyses on freshly frozen atrial tissue. Selected genes with enriched expression in either atrium were validated by RT-qPCR and Western blot in further animals and in shock-frozen left and right atrial appendages of patients undergoing open heart surgery.

Results: We identified 77 genes with preferential expression in one atrium that were common in all strains and age groups analysed. Independent of strain and age, Pitx2c was the gene with the highest enrichment in left atrium, while Bmp10, a member of the TGFβ family, showed highest enrichment in right atrium. These differences were validated by RT-qPCR in murine and human tissue. Western blot showed a 2-fold left-right concentration gradient in PITX2 protein in adult human atria. Several of the genes and gene groups enriched in left atria have a known biological role for maintenance of healthy physiology, specifically the prevention of atrial pathologies involved in atrial fibrillation, including membrane electrophysiology, metabolic cellular function, and regulation of inflammatory processes. Comparison of the array datasets with published array analyses in heterozygous Pitx2c(+/-) atria suggested that approximately half of the genes with left-sided enrichment are regulated by Pitx2c.

Conclusions: Our study reveals systematic differences between left and right atrial gene expression and supports the hypothesis that Pitx2c has a functional role in maintaining "leftness" in the atrium in adult murine and human hearts.

Show MeSH
Related in: MedlinePlus