Homocysteinylated protein levels in internal mammary artery (IMA) fragments and its genotype-dependence. S-Homocysteine-induced methylation modifications in IMA and aortic fragments

Abstract

The resistance of internal mammary artery (IMA) toward atherosclerosis is not well understood. In plasma, homocysteine (Hcy) occurs in reduced, oxidized, homocysteine thiolactone and a component of proteins as a result of N- or S-homocysteinylation. We evaluated S/N-homocysteinylated protein levels in IMA fragments of patients undergoing coronary artery bypass grafting, and whether they were affected by genetic common variants. We tested whether tHcy, Hcy-S-protein levels, genotypes or Hcy-induced methylation modifications were related to differences in iNOS, Ddah2, and eNOS gene expression between territories. A small percentage of Hcy-S-proteins were found in IMA fragments. The Mthfr C677T (rs1801133) and Pon-1 Leu55Met (rs854560) variants were associated with Hcy-S-proteins. We observed a gradual difference according to Hcy-S-protein levels in the methylation degree of the Ddah2 gene promoter in aortic, but not in IMA, fragments. No correlation between the degree of methylation and the Ddah2 gene expression levels was found in both types of analyzed fragments. Total Hcy but not Hcy-S-proteins correlated with iNOS promoter methylation. Analyzed variants seem to contribute to the in vivo Hcy binding properties to IMA. The contribution of the Hcy-derived methylation modifications to Ddah2 and eNOS gene expression seems to be tissue-specific and independent of the Ddah2/ADMA/eNOS pathway. Hcy-derived methylation modifications to the iNOS gene promoter contribute to a lesser extent to iNOS gene expression.

Long-term, regular remote ischemic preconditioning improves endothelial function in patients with coronary heart disease

“…However, these methods test peripheral arteries rather than coronary vascular endothelial function. To this end, we tested samples of the internal thoracic artery obtained during surgery (7,8). eNOS mRNA gene expression in artery samples (7,8) was higher in the RIPre group than in the CHD group.…”

“…To this end, we tested samples of the internal thoracic artery obtained during surgery (7,8). eNOS mRNA gene expression in artery samples (7,8) was higher in the RIPre group than in the CHD group. These results indicate that increased eNOS mRNA gene expression resulted from improved endothelial function (15).…”

“…In the CHD group, blood pressure was routinely measured three times daily. After 20 days, all patients underwent CABG surgery, and discarded artery fragments were collected following the procedure for later analysis (7,8). Routine patient treatment for CHD was maintained during the study in both the RIPre and CHD groups.…”

“…Cryosections of internal mammary artery fragments (7,8) were stained for CD34 (BD Pharmingen, USA), counterstained with FITC-fluorescence (Sigma, USA) and mounted with fluorescent mounting medium (Dako, Denmark). Sections were examined using a Nikon E600 fluorescence microscope (Japan) and the Lucia Measurement software 4.6 (India).…”

Role of homocysteinylation of ACE in endothelial dysfunction of arteries

“…Excessive accumulation of Hcy and HCTL can result in cellular dysfunction by covalently binding to proteins at cysteine (S-homocysteinylation) or at lysine (N-homocysteinylation) moieties, thereby causing alterations in protein function and/or aggregation of protein (21,45). Previous studies have characterized several proteins that are targeted by Hcy (48), including NOS (41,57), dimethylarginine dimethylaminohydrolase (46), LDL lipoproteins (9), and metallothioneins (1). In all cases, homocysteinylation modified their capacity to regulate metabolic pathways.…”