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- Naukkarinen, Jussi, et al.
(författare)
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Functional Variant Disrupts Insulin Induction of USF1 Mechanism for USF1-Associated Dyslipidemias
- 2009
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Ingår i: Circulation: Cardiovascular Genetics. - 1942-325X. ; 2:5, s. 245-522
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Tidskriftsartikel (refereegranskat)abstract
- Background-The upstream transcription factor 1 (USF1) gene is associated with familial combined hyperlipidemia, the most common genetic dyslipidemia in humans, as well as with various dyslipidemic changes in numerous other studies. Typical of complex disease-associated genes, neither the explicit mutations have been described nor the functional consequences for risk allele carriers been reported at the cellular or tissue level. Methods and Results-In this study, we aimed at describing the molecular mechanism through which the strongest associating intronic single-nucleotide polymorphism variant in USF1 is involved in the development of dyslipidemia. The effects of the risk variant on gene expression were studied in 2 relevant human tissues, fat and muscle. Global transcript profiles of 47 fat biopsies ascertained for carriership of the risk allele were tested for differential expression of known USF1 target genes as well as for broader effects on the transcript profile. Allelic imbalance of USF1 in fat was assessed using a quantitative sequencing approach. The possible allele-specific effect of insulin on the expression of USF1 was studied in 118 muscle biopsies before and after a euglycemic hyperinsulinemic clamp. The risk allele of single-nucleotide polymorphism rs2073658 seems to eradicate the inductive effect of insulin on the expression of USF1 in muscle and fat. The expression of numerous target genes is in turn perturbed in adipose tissue. Conclusions-In risk allele carriers, a defective response of USF1 to insulin results in the suboptimal response of relevant target genes that contributes to the enhanced risk of developing dyslipidemia and coronary heart disease. (Circ Cardiovasc Genet. 2009;2:522-529.)
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| 2. |
- Taskinen, Marja-Riitta, et al.
(författare)
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Contribution of intestinal triglyceride-rich lipoproteins to residual atherosclerotic cardiovascular disease risk in individuals with type 2 diabetes on statin therapy
- 2023
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Ingår i: DIABETOLOGIA. - 0012-186X .- 1432-0428. ; 66:12, s. 2307-2319
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Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis: This study explored the hypothesis that significant abnormalities in the metabolism of intestinally derived lipoproteins are present in individuals with type 2 diabetes on statin therapy. These abnormalities may contribute to residual CVD risk.Methods: To investigate the kinetics of ApoB-48- and ApoB-100-containing lipoproteins, we performed a secondary analysis of 11 overweight/obese individuals with type 2 diabetes who were treated with lifestyle counselling and on a stable dose of metformin who were from an earlier clinical study, and compared these with 11 control participants frequency-matched for age, BMI and sex. Participants in both groups were on a similar statin regimen during the study. Stable isotope tracers were used to determine the kinetics of the following in response to a standard fat-rich meal: (1) apolipoprotein (Apo)B-48 in chylomicrons and VLDL; (2) ApoB-100 in VLDL, intermediate-density lipoprotein (IDL) and LDL; and (3) triglyceride (TG) in VLDL.Results: The fasting lipid profile did not differ significantly between the two groups. Compared with control participants, in individuals with type 2 diabetes, chylomicron TG and ApoB-48 levels exhibited an approximately twofold higher response to the fat-rich meal, and a twofold higher increment was observed in ApoB-48 particles in the VLDL1 and VLDL2 density ranges (all p < 0.05). Again comparing control participants with individuals with type 2 diabetes, in the latter, total ApoB-48 production was 25% higher (556 +/- 57 vs 446 +/- 57 mg/day; p < 0.001), conversion (fractional transfer rate) of chylomicrons to VLDL was around 40% lower (35 +/- 25 vs 82 +/- 58 pools/day; p=0.034) and direct clearance of chylomicrons was 5.6-fold higher (5.6 +/- 2.2 vs 1.0 +/- 1.8 pools/day; p < 0.001). During the postprandial period, ApoB-48 particles accounted for a higher proportion of total VLDL in individuals with type 2 diabetes (44%) compared with control participants (25%), and these ApoB-48 VLDL particles exhibited a fivefold longer residence time in the circulation (p < 0.01). No between-group differences were seen in the kinetics of ApoB-100 and TG in VLDL, or in LDL ApoB-100 production, pool size and clearance rate. As compared with control participants, the IDL ApoB-100 pool in individuals with type 2 diabetes was higher due to increased conversion from VLDL2.Conclusions/interpretation: Abnormalities in the metabolism of intestinally derived ApoB-48-containing lipoproteins in individuals with type 2 diabetes on statins may help to explain the residual risk of CVD and may be suitable targets for interventions.
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