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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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Related in: MedlinePlus

Results of the mRNA expression array experiments.A Venn diagram showing the overlap of transcripts (grey numbers) that are significantly different between LA and RA (Fold-Change>1.5, P<0.05) in 3-month-old MF1 mice (MF1_3), 12-month-old MF1 mice (MF1-12), and 12-month-old Swiss-Agouti mice (SA_12). The number of transcripts with increased level of expression in the left atrium (black) or right atrium (white) are given in brackets. The overlapping 83 transcripts in the centre of the diagram refer to 77 single genes (see Tables 1 and 2). B Two-dimensional hierarchical clustering of relative change in gene expression using the 83 transcripts common to mice of all strains and age groups.
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pone-0026389-g001: Results of the mRNA expression array experiments.A Venn diagram showing the overlap of transcripts (grey numbers) that are significantly different between LA and RA (Fold-Change>1.5, P<0.05) in 3-month-old MF1 mice (MF1_3), 12-month-old MF1 mice (MF1-12), and 12-month-old Swiss-Agouti mice (SA_12). The number of transcripts with increased level of expression in the left atrium (black) or right atrium (white) are given in brackets. The overlapping 83 transcripts in the centre of the diagram refer to 77 single genes (see Tables 1 and 2). B Two-dimensional hierarchical clustering of relative change in gene expression using the 83 transcripts common to mice of all strains and age groups.

Mentions: In the 3 microarray datasets (MF1_3, MF1_12, SA_12) a total number of 624 gene probes were found to be significantly differentially expressed in the mouse left and right atrium (Figure 1A, heat map in Figure 1B, complete list in Supplementary Table S1), corresponding to 576 transcripts of 534 genes. Of these, 118 gene probes overlapped between two and 83 probes across all three datasets, corresponding to 77 genes (see Tables 1 and 2). All overlapping genes had consistently higher expression values on the left or right atrial side across all datasets. Overall, more gene probes had higher expression values on the right atrial side (59%, 368 vs. 256). Different array probes targeting the same genes usually gave highly consistent (>95% of cases) results in terms of differential gene expression, suggesting overall reliable data from a technical point of view.


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)

Results of the mRNA expression array experiments.A Venn diagram showing the overlap of transcripts (grey numbers) that are significantly different between LA and RA (Fold-Change>1.5, P<0.05) in 3-month-old MF1 mice (MF1_3), 12-month-old MF1 mice (MF1-12), and 12-month-old Swiss-Agouti mice (SA_12). The number of transcripts with increased level of expression in the left atrium (black) or right atrium (white) are given in brackets. The overlapping 83 transcripts in the centre of the diagram refer to 77 single genes (see Tables 1 and 2). B Two-dimensional hierarchical clustering of relative change in gene expression using the 83 transcripts common to mice of all strains and age groups.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0026389-g001: Results of the mRNA expression array experiments.A Venn diagram showing the overlap of transcripts (grey numbers) that are significantly different between LA and RA (Fold-Change>1.5, P<0.05) in 3-month-old MF1 mice (MF1_3), 12-month-old MF1 mice (MF1-12), and 12-month-old Swiss-Agouti mice (SA_12). The number of transcripts with increased level of expression in the left atrium (black) or right atrium (white) are given in brackets. The overlapping 83 transcripts in the centre of the diagram refer to 77 single genes (see Tables 1 and 2). B Two-dimensional hierarchical clustering of relative change in gene expression using the 83 transcripts common to mice of all strains and age groups.
Mentions: In the 3 microarray datasets (MF1_3, MF1_12, SA_12) a total number of 624 gene probes were found to be significantly differentially expressed in the mouse left and right atrium (Figure 1A, heat map in Figure 1B, complete list in Supplementary Table S1), corresponding to 576 transcripts of 534 genes. Of these, 118 gene probes overlapped between two and 83 probes across all three datasets, corresponding to 77 genes (see Tables 1 and 2). All overlapping genes had consistently higher expression values on the left or right atrial side across all datasets. Overall, more gene probes had higher expression values on the right atrial side (59%, 368 vs. 256). Different array probes targeting the same genes usually gave highly consistent (>95% of cases) results in terms of differential gene expression, suggesting overall reliable data from a technical point of view.

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