Supplementary_Material_GLUL_HUVEC_061620_clean.pdf (312.44 kB)
Download fileAssociation of the 1q25 diabetes-specific coronary heart disease locus with alterations of the γ-glutamyl cycle and increased methylglyoxal levels in endothelial cells
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posted on 2020-07-10, 16:55 authored by Ada AdminAda Admin, Caterina Pipino, Hetal Shah, Sabrina Prudente, Natalia Di Pietro, Lixia Zeng, Kyoungmin Park, Vincenzo Trischitta, Subramanian Pennathur, Assunta Pandolfi, Alessandro DoriaA chromosome 1q25 variant
(rs10911021) has been associated with coronary heart disease (CHD) in type 2
diabetes (T2D). In human umbilical vein endothelial cells (HUVECs), the risk
allele ‘C’ is associated with lower expression of the adjacent gene GLUL encoding glutamine synthase,
converting glutamic acid to glutamine. To further investigate the mechanisms
through which this locus affects CHD risk, we measured 35 intracellular
metabolites involved in glutamic acid metabolism and g-glutamyl cycle in 62 HUVEC strains carrying different
rs10911021 genotypes. Eight metabolites
were positively associated with the
risk allele (17%-58% increase/allele copy, p=0.046-0.002), including five g-glutamyl amino acids, b-citryl-glutamate, N-acetyl-aspartyl-glutamate, and ophthalmate - a marker of g-glutamyl cycle malfunction. Consistent with these
findings, the risk allele was also associated with decreased
glutathione/glutamate ratio (-9%, p=0.012), decreased S-lactoylglutathione
(-41%, p=0.019), and reduced
detoxification of the atherogenic compound methylglyoxal (+54%, p=0.008). GLUL down-regulation by shRNA caused a
40% increase in methylglyoxal level, which was completely prevented by
glutamine supplementation. In summary, we have identified intracellular
metabolic traits associated with the 1q25 risk allele in HUVECs, including
impairments of the g-glutamyl
cycle and methylglyoxal
detoxification. Glutamine
supplementation abolishes the latter abnormality, suggesting that such
treatment may prevent CHD in 1q25 risk allele carriers.