| 1. |
- Williamson, Alice, et al.
(författare)
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Genome-wide association study and functional characterization identifies candidate genes for insulin-stimulated glucose uptake
- 2023
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Ingår i: Nature Genetics. - : Springer Nature. - 1061-4036 .- 1546-1718. ; 55:6, s. 973-983
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Tidskriftsartikel (refereegranskat)abstract
- Distinct tissue-specific mechanisms mediate insulin action in fasting and postprandial states. Previous genetic studies have largely focused on insulin resistance in the fasting state, where hepatic insulin action dominates. Here we studied genetic variants influencing insulin levels measured 2 h after a glucose challenge in >55,000 participants from three ancestry groups. We identified ten new loci (P < 5 × 10-8) not previously associated with postchallenge insulin resistance, eight of which were shown to share their genetic architecture with type 2 diabetes in colocalization analyses. We investigated candidate genes at a subset of associated loci in cultured cells and identified nine candidate genes newly implicated in the expression or trafficking of GLUT4, the key glucose transporter in postprandial glucose uptake in muscle and fat. By focusing on postprandial insulin resistance, we highlighted the mechanisms of action at type 2 diabetes loci that are not adequately captured by studies of fasting glycemic traits.
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| 2. |
- de Mello, Vanessa D., et al.
(författare)
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Serum aromatic and branched-chain amino acids associated with NASH demonstrate divergent associations with serum lipids
- 2021
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Ingår i: Liver International. - : Wiley. - 1478-3223 .- 1478-3231. ; 41:4, s. 754-763
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Tidskriftsartikel (refereegranskat)abstract
- Background & Aims: Non-alcoholic fatty liver disease (NAFLD) has been associated with multiple metabolic abnormalities. By applying a non-targeted metabolomics approach, we aimed at investigating whether serum metabolite profile that associates with NAFLD would differ in its association with NAFLD-related metabolic risk factors. Methods & Results: A total of 233 subjects (mean ± SD: 48.3 ± 9.3 years old; BMI: 43.1 ± 5.4 kg/m2; 64 male) undergoing bariatric surgery were studied. Of these participants, 164 with liver histology could be classified as normal liver (n = 79), simple steatosis (SS, n = 40) or non-alcoholic steatohepatitis (NASH, n = 45). Among the identified fasting serum metabolites with higher levels in those with NASH when compared to those with normal phenotype were the aromatic amino acids (AAAs: tryptophan, tyrosine and phenylalanine), the branched-chain amino acids (BCAAs: leucine and isoleucine), a phosphatidylcholine (PC(16:0/16:1)) and uridine (all FDRp < 0.05). Only tryptophan was significantly higher in those with NASH compared to those with SS (FDRp < 0.05). Only the AAAs tryptophan and tyrosine correlated positively with serum total and LDL cholesterol (FDRp < 0.1), and accordingly, with liver LDLR at mRNA expression level. In addition, tryptophan was the single AA associated with liver DNA methylation of CpG sites known to be differentially methylated in those with NASH. Conclusions: We found that serum levels of the NASH-related AAAs and BCAAs demonstrate divergent associations with serum lipids. The specific correlation of tryptophan with LDL-c may result from the molecular events affecting LDLR mRNA expression and NASH-associated methylation of genes in the liver.
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| 3. |
- Murphy, Rachel A, et al.
(författare)
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Omega-3 and omega-6 polyunsaturated fatty acid biomarkers and sleep : a pooled analysis of cohort studies On behalf of the Fatty Acids and Outcomes Research Consortium (FORCE).
- 2022
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Ingår i: American Journal of Clinical Nutrition. - : Oxford University Press (OUP). - 0002-9165 .- 1938-3207. ; 115:3, s. 864-876
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: n-3 and n-6 polyunsaturated fatty acids (PUFAs) have physiologic roles in sleep processes, but little is known regarding circulating n-3 and n-6 PUFA and sleep parameters.OBJECTIVES: To assess associations between biomarkers of n-3 and n-6 PUFA intake with self-reported sleep duration and difficulty falling sleeping in the Fatty Acids and Outcome Research Consortium.METHODS: Harmonized, de novo, individual-level analyses were performed and pooled across 12 cohorts. Participants were between 35 to 96 years old and from 5 nations. Circulating measures included alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), docosahexaenoic acid (DHA), EPA + DPA + DHA, linoleic acid and arachidonic acid. Sleep duration (10 cohorts, N = 18,791) was categorized as short (≤6 hours), 7-8 hours (reference) or long (9 + hours). Difficulty falling sleeping (8 cohorts, N = 12,500) was categorized as yes or no. Associations between PUFAs, sleep duration, and difficulty falling sleeping were assessed by cross-sectional multinomial logistic regression using standardized protocols and covariates. Cohort-specific multivariable-adjusted odds ratios (ORs) per quintile of PUFAs were pooled with inverse-variance weighted meta-analysis.RESULTS: In pooled analysis adjusted for sociodemographics and health status, participants with higher very long-chain n-3 PUFAs were less likely to have long sleep duration. Comparing top vs. bottom quintiles, the multivariable-adjusted OR (95% confidence interval, CI) for long-sleep was 0.78 (0.65, 0.95) for DHA and for EPA + DPA + DHA, 0.76 (0.63, 0.93). Significant associations were not identified for ALA and n-6 PUFA with short sleep duration, or difficulty falling sleeping.CONCLUSIONS: Participants with higher levels of very long-chain n-3 PUFAs were less likely to have long sleep duration. While objective biomarkers reduce recall bias and misclassification, the cross-sectional design limits assessment of the temporal nature of this relationship. These novel findings across 12 cohorts highlight the need for experimental and biological assessments of very long-chain n-3 PUFAs and sleep duration.
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| 4. |
- Qian, Frank, et al.
(författare)
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n-3 Fatty Acid Biomarkers and Incident Type 2 Diabetes : An Individual Participant-Level Pooling Project of 20 Prospective Cohort Studies
- 2021
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Ingår i: Diabetes Care. - : American Diabetes Association. - 0149-5992 .- 1935-5548. ; 44:5, s. 1133-1142
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE Prospective associations between n-3 fatty acid biomarkers and type 2 diabetes (T2D) risk are not consistent in individual studies. We aimed to summarize the prospective associations of biomarkers of alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA) with T2D risk through an individual participant-level pooled analysis.RESEARCH DESIGN AND METHODS For our analysis we incorporated data from a global consortium of 20 prospective studies from 14 countries. We included 65,147 participants who had blood measurements of ALA, EPA, DPA, or DHA and were free of diabetes at baseline. De novo harmonized analyses were performed in each cohort following a pre-specified protocol, and cohort-specific associations were pooled using inverse variance-weighted meta-analysis.RESULTS A total of 16,693 incident T2D cases were identified during follow-up (median follow-up ranging from 2.5 to 21.2 years). In pooled multivariable analysis, per interquintile range (difference between the 90th and 10th percentiles for each fatty acid), EPA, DPA, DHA, and their sum were associated with lower T2D incidence, with hazard ratios (HRs) and 95% CIs of 0.92 (0.87, 0.96), 0.79 (0.73, 0.85), 0.82 (0.76, 0.89), and 0.81 (0.75, 0.88), respectively (all P < 0.001). ALA was not associated with T2D (HR 0.97 [95% CI 0.92, 1.02]) per interquintile range. Associations were robust across prespecified subgroups as well as in sensitivity analyses.CONCLUSIONS Higher circulating biomarkers of seafood-derived n-3 fatty acids, including EPA, DPA, DHA, and their sum, were associated with lower risk of T2D in a global consortium of prospective studies. The biomarker of plant-derived ALA was not significantly associated with T2D risk.
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| 5. |
- Sehgal, Ratika, et al.
(författare)
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Liver saturated fat content associates with hepatic DNA methylation in obese individuals
- 2023
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Ingår i: Clinical Epigenetics. - : Springer Science and Business Media LLC. - 1868-7075 .- 1868-7083. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Accumulation of saturated fatty acids (SFAs) in the liver is known to induce hepatic steatosis and inflammation causing non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). Although SFAs have been shown to affect the epigenome in whole blood, pancreatic islets, and adipose tissue in humans, and genome-wide DNA methylation studies have linked epigenetic changes to NAFLD and NASH, studies focusing on the association of SFAs and DNA methylation in human liver are missing. We, therefore, investigated whether human liver SFA content associates with DNA methylation and tested if SFA-linked alterations in DNA methylation associate with NAFLD-related clinical phenotypes in obese individuals. Results: We identified DNA methylation (Infinium HumanMethylation450 BeadChip) of 3169 CpGs to be associated with liver total SFA content (q-value < 0.05) measured using proton NMR spectroscopy in participants of the Kuopio Obesity Surgery Study (n = 51; mean ± SD:49.3 ± 8.5 years old; BMI:43.7 ± 6.2 kg/m2). Of these 3169 sites, 797 overlapped with previously published NASH-associated CpGs (NASH-SFA), while 2372 CpGs were exclusively associated with SFA (Only-SFA). The corresponding annotated genes of these only-SFA CpGs were found to be enriched in pathways linked to satiety and hunger. Among the 54 genes mapping to these enriched pathways, DNA methylation of CpGs mapping to PRKCA and TSPO correlated with their own mRNA expression (HumanHT-12 Expression BeadChip). In addition, DNA methylation of another ten of these CpGs correlated with the mRNA expression of their neighboring genes (p value < 0.05). The proportion of CpGs demonstrating a correlation of DNA methylation with plasma glucose was higher in NASH-SFA and only-SFA groups, while the proportion of significant correlations with plasma insulin was higher in only-NASH and NASH-SFA groups as compared to all CpGs on the Illumina 450 K array (Illumina, San Diego, CA, USA). Conclusions: Our results suggest that one of the mechanisms how SFA could contribute to metabolic dysregulation in NAFLD is at the level of DNA methylation. We further propose that liver SFA-related DNA methylation profile may contribute more to hyperglycemia, while insulin-related methylation profile is more linked to NAFLD or NASH. Further research is needed to elucidate the molecular mechanisms behind these observations.
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| 6. |
- U-Din, Mueez, et al.
(författare)
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Cold-stimulated brown adipose tissue activation is related to changes in serum metabolites relevant to NAD + metabolism in humans
- 2023
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Ingår i: Cell Reports. - 2211-1247. ; 42:9
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Tidskriftsartikel (refereegranskat)abstract
- Cold-induced brown adipose tissue (BAT) activation is considered to improve metabolic health. In murine BAT, cold increases the fundamental molecule for mitochondrial function, nicotinamide adenine dinucleotide (NAD+), but limited knowledge of NAD+ metabolism during cold in human BAT metabolism exists. We show that cold increases the serum metabolites of the NAD+ salvage pathway (nicotinamide and 1-methylnicotinamide) in humans. Additionally, individuals with cold-stimulated BAT activation have decreased levels of metabolites from the de novo NAD+ biosynthesis pathway (tryptophan, kynurenine). Serum nicotinamide correlates positively with cold-stimulated BAT activation, whereas tryptophan and kynurenine correlate negatively. Furthermore, the expression of genes involved in NAD+ biosynthesis in BAT is related to markers of metabolic health. Our data indicate that cold increases serum tryptophan conversion to nicotinamide to be further utilized by BAT. We conclude that NAD+ metabolism is activated upon cold in humans and is probably regulated in a coordinated fashion by several tissues.
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