Homocysteine inhibits arterial endothelial cell growth through transcriptional downregulation of fibroblast growth factor-2 involving G protein and DNA methylation

Po Yuan Chang, Shao Chun Lu, Chii Ming Lee, Yi Jie Chen, Tracey A. Dugan, Wen Huei Huang, Shwu Fen Chang, Warren S L Liao, Chu Huang Chen, Yuan Teh Lee

Research output: Contribution to journalArticle

69 Citations (Scopus)

Abstract

Homocysteine (Hcy) contributes to atherogenesis and angiostasis by altering the phenotype of arterial endothelial cells (ECs). The present study was aimed at elucidating potential mechanisms by which Hcy can slow EC proliferation and induce EC apoptosis, thereby disrupting endothelial integrity. Given the strong mitogenic and antiapoptotic properties of fibroblast growth factor (FGF)2, we examined whether Hcy can modulate its expression. In cultured human coronary and bovine aortic ECs, Hcy exerted time- and concentration-dependent (0 to 500 μmol/L) reduction of the mRNA and protein levels of FGF2, whereas vascular endothelial growth factor expression was not affected until Hcy reached a proapoptotic 500 μmol/L. By testing a panel of signal transduction inhibitors, we found that the Hcy-induced downregulation of FGF2 was specifically attenuated by pertussis toxin, an inhibitor of Gi protein signaling. Hcy induced cell cycle arrest at the G1/S transition and increased TUNEL-positive apoptotic cells in a graded manner. These effects were effectively counteracted by exogenous FGF2. Reporter gene assays showed that Hcy downregulated FGF2 by transcriptional repression of the gene promoter encompassed in a CpG dinucleotide-rich island. This region was heavily methylated at the cytosine residues by Hcy despite decreased methylation potential (S-adenosylmethionine to S-adenosylhomocysteine ratio). Normal levels of FGF2 transcription were restored to ECs simultaneously exposed to Hcy and 5-aza-deoxycytidine. We conclude that homocysteine disrupts the growth and survival of ECs through a G protein-mediated pathway associated with altered promoter DNA methylation and the transcriptional repression of FGF2.

Original languageEnglish
Pages (from-to)933-941
Number of pages9
JournalCirculation Research
Volume102
Issue number8
DOIs
Publication statusPublished - Apr 2008

Fingerprint

Homocysteine
Fibroblast Growth Factor 2
DNA Methylation
GTP-Binding Proteins
Down-Regulation
Endothelial Cells
Growth
S-Adenosylhomocysteine
G1 Phase Cell Cycle Checkpoints
S-Adenosylmethionine
Deoxycytidine
CpG Islands
Cytosine
Pertussis Toxin
In Situ Nick-End Labeling
Reporter Genes
Methylation
Vascular Endothelial Growth Factor A
Signal Transduction
Atherosclerosis

Keywords

  • DNA methylation
  • Endothelial cells
  • Growth factors
  • Homocysteine
  • Transcriptional regulation

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

Cite this

Homocysteine inhibits arterial endothelial cell growth through transcriptional downregulation of fibroblast growth factor-2 involving G protein and DNA methylation. / Chang, Po Yuan; Lu, Shao Chun; Lee, Chii Ming; Chen, Yi Jie; Dugan, Tracey A.; Huang, Wen Huei; Chang, Shwu Fen; Liao, Warren S L; Chen, Chu Huang; Lee, Yuan Teh.

In: Circulation Research, Vol. 102, No. 8, 04.2008, p. 933-941.

Research output: Contribution to journalArticle

Chang, Po Yuan ; Lu, Shao Chun ; Lee, Chii Ming ; Chen, Yi Jie ; Dugan, Tracey A. ; Huang, Wen Huei ; Chang, Shwu Fen ; Liao, Warren S L ; Chen, Chu Huang ; Lee, Yuan Teh. / Homocysteine inhibits arterial endothelial cell growth through transcriptional downregulation of fibroblast growth factor-2 involving G protein and DNA methylation. In: Circulation Research. 2008 ; Vol. 102, No. 8. pp. 933-941.
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AU - Chang, Po Yuan

AU - Lu, Shao Chun

AU - Lee, Chii Ming

AU - Chen, Yi Jie

AU - Dugan, Tracey A.

AU - Huang, Wen Huei

AU - Chang, Shwu Fen

AU - Liao, Warren S L

AU - Chen, Chu Huang

AU - Lee, Yuan Teh

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N2 - Homocysteine (Hcy) contributes to atherogenesis and angiostasis by altering the phenotype of arterial endothelial cells (ECs). The present study was aimed at elucidating potential mechanisms by which Hcy can slow EC proliferation and induce EC apoptosis, thereby disrupting endothelial integrity. Given the strong mitogenic and antiapoptotic properties of fibroblast growth factor (FGF)2, we examined whether Hcy can modulate its expression. In cultured human coronary and bovine aortic ECs, Hcy exerted time- and concentration-dependent (0 to 500 μmol/L) reduction of the mRNA and protein levels of FGF2, whereas vascular endothelial growth factor expression was not affected until Hcy reached a proapoptotic 500 μmol/L. By testing a panel of signal transduction inhibitors, we found that the Hcy-induced downregulation of FGF2 was specifically attenuated by pertussis toxin, an inhibitor of Gi protein signaling. Hcy induced cell cycle arrest at the G1/S transition and increased TUNEL-positive apoptotic cells in a graded manner. These effects were effectively counteracted by exogenous FGF2. Reporter gene assays showed that Hcy downregulated FGF2 by transcriptional repression of the gene promoter encompassed in a CpG dinucleotide-rich island. This region was heavily methylated at the cytosine residues by Hcy despite decreased methylation potential (S-adenosylmethionine to S-adenosylhomocysteine ratio). Normal levels of FGF2 transcription were restored to ECs simultaneously exposed to Hcy and 5-aza-deoxycytidine. We conclude that homocysteine disrupts the growth and survival of ECs through a G protein-mediated pathway associated with altered promoter DNA methylation and the transcriptional repression of FGF2.

AB - Homocysteine (Hcy) contributes to atherogenesis and angiostasis by altering the phenotype of arterial endothelial cells (ECs). The present study was aimed at elucidating potential mechanisms by which Hcy can slow EC proliferation and induce EC apoptosis, thereby disrupting endothelial integrity. Given the strong mitogenic and antiapoptotic properties of fibroblast growth factor (FGF)2, we examined whether Hcy can modulate its expression. In cultured human coronary and bovine aortic ECs, Hcy exerted time- and concentration-dependent (0 to 500 μmol/L) reduction of the mRNA and protein levels of FGF2, whereas vascular endothelial growth factor expression was not affected until Hcy reached a proapoptotic 500 μmol/L. By testing a panel of signal transduction inhibitors, we found that the Hcy-induced downregulation of FGF2 was specifically attenuated by pertussis toxin, an inhibitor of Gi protein signaling. Hcy induced cell cycle arrest at the G1/S transition and increased TUNEL-positive apoptotic cells in a graded manner. These effects were effectively counteracted by exogenous FGF2. Reporter gene assays showed that Hcy downregulated FGF2 by transcriptional repression of the gene promoter encompassed in a CpG dinucleotide-rich island. This region was heavily methylated at the cytosine residues by Hcy despite decreased methylation potential (S-adenosylmethionine to S-adenosylhomocysteine ratio). Normal levels of FGF2 transcription were restored to ECs simultaneously exposed to Hcy and 5-aza-deoxycytidine. We conclude that homocysteine disrupts the growth and survival of ECs through a G protein-mediated pathway associated with altered promoter DNA methylation and the transcriptional repression of FGF2.

KW - DNA methylation

KW - Endothelial cells

KW - Growth factors

KW - Homocysteine

KW - Transcriptional regulation

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