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Identification of New SRF Binding Sites in Genes Modulated by SRF Over-Expression in Mouse Hearts.

Zhang X, Azhar G, Helms S, Burton B, Huang C, Zhong Y, Gu X, Fang H, Tong W, Wei JY - Gene Regul Syst Bio (2011)

Bottom Line: The expression of genes that are involved in transcription and ion regulation were decreased, but expression of cytoskeletal genes was significantly increased.Hence, the mild elevation of SRF protein in the heart that is observed during typical adult aging may have a major impact on many SRF-modulated genes, thereby affecting cardiac structure and performance.The results from our study could help to enhance our understanding of SRF regulation of cellular processes in the aged heart.

View Article: PubMed Central - PubMed

Affiliation: Donald W. Reynolds Department of Geriatrics, The University of Arkansas for Medical Sciences and Geriatric Research, Education, and Clinical Center, Central Arkansas Veterans Healthcare System, Little Rock, AR 72205, USA.

ABSTRACT

Background: To identify in vivo new cardiac binding sites of serum response factor (SRF) in genes and to study the response of these genes to mild over-expression of SRF, we employed a cardiac-specific, transgenic mouse model, with mild over-expression of SRF (Mild-O SRF Tg).

Methodology: Microarray experiments were performed on hearts of Mild-O-SRF Tg at 6 months of age. We identified 207 genes that are important for cardiac function that were differentially expressed in vivo. Among them the promoter region of 192 genes had SRF binding motifs, the classic CArG or CArG-like (CArG-L) elements. Fifty-one of the 56 genes with classic SRF binding sites had not been previously reported. These SRF-modulated genes were grouped into 12 categories based on their function. It was observed that genes associated with cardiac energy metabolism shifted toward that of carbohydrate metabolism and away from that of fatty acid metabolism. The expression of genes that are involved in transcription and ion regulation were decreased, but expression of cytoskeletal genes was significantly increased. Using public databases of mouse models of hemodynamic stress (GEO database), we also found that similar altered expression of the SRF-modulated genes occurred in these hearts with cardiac ischemia or aortic constriction as well.

Conclusion and significance: SRF-modulated genes are actively regulated under various physiological and pathological conditions. We have discovered that a large number of cardiac genes have classic SRF binding sites and were significantly modulated in the Mild-O-SRF Tg mouse hearts. Hence, the mild elevation of SRF protein in the heart that is observed during typical adult aging may have a major impact on many SRF-modulated genes, thereby affecting cardiac structure and performance. The results from our study could help to enhance our understanding of SRF regulation of cellular processes in the aged heart.

No MeSH data available.


Related in: MedlinePlus

The results of real-time RT-PCR are given as a relative expression of mRNA normalized to the 18S housekeeping gene, fold change in gene expression. n = 5 mice in Mild-O SRF Tg (trangenic mouse with mild over-expression of SRF) and non-transgenic group. Results are provided as means ± SD.Note: *P < 0.05 Non-Tg, vs. Mild-O SRF Tg using the Mann Whitney U test.
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f5-grsb-5-2011-041: The results of real-time RT-PCR are given as a relative expression of mRNA normalized to the 18S housekeeping gene, fold change in gene expression. n = 5 mice in Mild-O SRF Tg (trangenic mouse with mild over-expression of SRF) and non-transgenic group. Results are provided as means ± SD.Note: *P < 0.05 Non-Tg, vs. Mild-O SRF Tg using the Mann Whitney U test.

Mentions: All genes that were differentially expressed ≥2 fold were validated with real-time RT-PCR and representative results are depicted in Figure 5A and 5B. B4galnt1 (beta-1,4-n-acetyl-galactosaminyl transferase 1), important in energy metabolism and the synthesis of gangliosides, was elevated 7 fold in the Mild-O-SRF Tg mouse hearts. Abnormalities in ganglioside metabolism maybe associated with Type I diabetes mellitus.37 Expression of Apod (ApolipoproteinD) a soluble lipid carrier is found in most human tissues, but especially in glia of the nervous system.38–41 Its expression was increased 3.6 fold in the Mild-O-SRF Tg (Fig. 5A). Acot9 was increased 2 fold in Mild-O-SRF Tg. Acyl CoA is important in triglyceride synthesis and its increase can potentially increase cardiovascular risk profile (Fig. 5A).42 CoasyCoA synthase (CoASy) was decreased in the Mild-O-SRF Tg hearts (Fig. 5A). Coasyis a mitochondria-associated enzyme which mediates two final stages of de novo CoA biosynthesis.43 Pafah1b3 (platelet activating factor acetylhydrolase) and Pfkp (phosphofructokinase) which is involved in adiposity were also confirmed with qRT-PCR (Fig. 5A).44,45 Anxa10 was elevated more than 13 fold on q-RT-PCR (Fig. 5B).34,35


Identification of New SRF Binding Sites in Genes Modulated by SRF Over-Expression in Mouse Hearts.

Zhang X, Azhar G, Helms S, Burton B, Huang C, Zhong Y, Gu X, Fang H, Tong W, Wei JY - Gene Regul Syst Bio (2011)

The results of real-time RT-PCR are given as a relative expression of mRNA normalized to the 18S housekeeping gene, fold change in gene expression. n = 5 mice in Mild-O SRF Tg (trangenic mouse with mild over-expression of SRF) and non-transgenic group. Results are provided as means ± SD.Note: *P < 0.05 Non-Tg, vs. Mild-O SRF Tg using the Mann Whitney U test.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3140411&req=5

f5-grsb-5-2011-041: The results of real-time RT-PCR are given as a relative expression of mRNA normalized to the 18S housekeeping gene, fold change in gene expression. n = 5 mice in Mild-O SRF Tg (trangenic mouse with mild over-expression of SRF) and non-transgenic group. Results are provided as means ± SD.Note: *P < 0.05 Non-Tg, vs. Mild-O SRF Tg using the Mann Whitney U test.
Mentions: All genes that were differentially expressed ≥2 fold were validated with real-time RT-PCR and representative results are depicted in Figure 5A and 5B. B4galnt1 (beta-1,4-n-acetyl-galactosaminyl transferase 1), important in energy metabolism and the synthesis of gangliosides, was elevated 7 fold in the Mild-O-SRF Tg mouse hearts. Abnormalities in ganglioside metabolism maybe associated with Type I diabetes mellitus.37 Expression of Apod (ApolipoproteinD) a soluble lipid carrier is found in most human tissues, but especially in glia of the nervous system.38–41 Its expression was increased 3.6 fold in the Mild-O-SRF Tg (Fig. 5A). Acot9 was increased 2 fold in Mild-O-SRF Tg. Acyl CoA is important in triglyceride synthesis and its increase can potentially increase cardiovascular risk profile (Fig. 5A).42 CoasyCoA synthase (CoASy) was decreased in the Mild-O-SRF Tg hearts (Fig. 5A). Coasyis a mitochondria-associated enzyme which mediates two final stages of de novo CoA biosynthesis.43 Pafah1b3 (platelet activating factor acetylhydrolase) and Pfkp (phosphofructokinase) which is involved in adiposity were also confirmed with qRT-PCR (Fig. 5A).44,45 Anxa10 was elevated more than 13 fold on q-RT-PCR (Fig. 5B).34,35

Bottom Line: The expression of genes that are involved in transcription and ion regulation were decreased, but expression of cytoskeletal genes was significantly increased.Hence, the mild elevation of SRF protein in the heart that is observed during typical adult aging may have a major impact on many SRF-modulated genes, thereby affecting cardiac structure and performance.The results from our study could help to enhance our understanding of SRF regulation of cellular processes in the aged heart.

View Article: PubMed Central - PubMed

Affiliation: Donald W. Reynolds Department of Geriatrics, The University of Arkansas for Medical Sciences and Geriatric Research, Education, and Clinical Center, Central Arkansas Veterans Healthcare System, Little Rock, AR 72205, USA.

ABSTRACT

Background: To identify in vivo new cardiac binding sites of serum response factor (SRF) in genes and to study the response of these genes to mild over-expression of SRF, we employed a cardiac-specific, transgenic mouse model, with mild over-expression of SRF (Mild-O SRF Tg).

Methodology: Microarray experiments were performed on hearts of Mild-O-SRF Tg at 6 months of age. We identified 207 genes that are important for cardiac function that were differentially expressed in vivo. Among them the promoter region of 192 genes had SRF binding motifs, the classic CArG or CArG-like (CArG-L) elements. Fifty-one of the 56 genes with classic SRF binding sites had not been previously reported. These SRF-modulated genes were grouped into 12 categories based on their function. It was observed that genes associated with cardiac energy metabolism shifted toward that of carbohydrate metabolism and away from that of fatty acid metabolism. The expression of genes that are involved in transcription and ion regulation were decreased, but expression of cytoskeletal genes was significantly increased. Using public databases of mouse models of hemodynamic stress (GEO database), we also found that similar altered expression of the SRF-modulated genes occurred in these hearts with cardiac ischemia or aortic constriction as well.

Conclusion and significance: SRF-modulated genes are actively regulated under various physiological and pathological conditions. We have discovered that a large number of cardiac genes have classic SRF binding sites and were significantly modulated in the Mild-O-SRF Tg mouse hearts. Hence, the mild elevation of SRF protein in the heart that is observed during typical adult aging may have a major impact on many SRF-modulated genes, thereby affecting cardiac structure and performance. The results from our study could help to enhance our understanding of SRF regulation of cellular processes in the aged heart.

No MeSH data available.


Related in: MedlinePlus