Supplementary_Material_GLUL_HUVEC_061620_clean.pdf (312.44 kB)

Association 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 10.07.2020 by Ada Admin, Caterina Pipino, Hetal Shah, Sabrina Prudente, Natalia Di Pietro, Lixia Zeng, Kyoungmin Park, Vincenzo Trischitta, Subramanian Pennathur, Assunta Pandolfi, Alessandro Doria
A 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.

Funding

This research was supported by a research grant from Sanofi-Aventis (to A.D.), NIH grant DK36836 (Molecular Phenotyping and Genotyping Core and Enrichment Core of the Diabetes Research Center at the Joslin Diabetes Center), NIH grants DK081943 and DK082841 (to Su.P.), the Italian Ministry of Health (Ricerca Corrente 2019-2020 to V.T and 2018-2020 to Sa.P.), the Italian Ministry of University and Research (PRIN 2015 to V.T.), and Fondazione Roma (Grant for Biomedical Research: Non Communicable Diseases, Call for proposals 2013 to V.T.).

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