The rs2910164 variant is associated with reduced miR-146a expression but not cytokine levels in patients with type 2 diabetes

PURPOSE

Previous reports have demonstrated that genetic variations in microRNAs regulome could affect microRNAs-mediated regulation. Therefore, in the present study we were aimed at (1) comparison of microRNA 146-a (miR-146a) peripheral blood mononuclear cells (PBMCs) and plasma levels between diabetic patients and controls, and (2) investigating the possible association of rs2910164 with miR-146a and its related target genes expression and also serum cytokine levels.

METHODS

The study population consisted of 60 subjects including 30 type 2 diabetes (T2D) patients and 30 controls with determined genotypes for rs2910164. The RNA expression levels were determined by real-time PCR. Moreover, TNF-α, IL-6, IL-10 and IL-1β serum levels were measured using ELISA method.

RESULTS

Our results showed that the miR-146a expression levels were significantly decreased in PBMCs (P = 0.004) and plasma (P = 0.008) samples of patients with T2D compared to healthy participants. In addition, we observed that IRAK1 mRNA expression-but not TLR4, TRAF6 and NFĸB-was significantly increased in patients with T2D compared to controls (P = 0.028). The relative expression levels of miR-146a in plasma and PBMCs samples of diabetic patients with the rs2910164 GG genotypes were significantly higher than that in CC (P < 0.05). Moreover, no significant differences were found in miR-146a targets and cytokine levels between the rs2910164 different genotypes.

CONCLUSION

Our study demonstrated that miR-146a circulating levels were significantly elevated in controls compared with T2D patients. In addition, we identified that rs2910164-C allele is associated with reduced expression levels of the miR-146a but not its mRNAs targets and cytokine levels in diabetic patients.

Alternate-day fasting diet improves fructose-induced insulin resistance in mice

Increased fructose consumption is linked to insulin resistance, weight gain, hyperlipidemia and hypertension. Although the advantages of several dietary restriction regimens have been demonstrated, the effects of alternate-day fasting (ADF) on fructose-induced insulin resistance have not yet been studied. This study is based on a new modification on ADF by combining the fructose-rich solution (10% w/v) and regular mice diet. Mice were randomly allocated into four groups: ADF50% (50% restriction in chow food intake but ad libitum fructose drink), ADF100% (100% restriction for chow food but ad libitum fructose drink), control (ad libitum chow food intake plus tap water) and daily food and fructose (DFF) (had free access to both chow and fructose solution). Biweekly fasting blood sugar (FBS), glucose tolerance test (GTT) and insulin tolerance test (ITT) were conducted. All groups gained weight during the study (p < 0.05). Body weights of DFF and control groups did not differ from that of ADF groups, but ADF50% gained more (p < 0.01) weights than ADF100% through the study. Total calorie intake (feed + fast days) of ADF50% was higher than that of ADF100% (p < 0.001) and control (p < 0.03). In addition, ADF groups consumed more energy than the control and DFF groups in feed (ad libitum) days (p < 0.05). At the end of the study, the mean FBS levels in the control and ADF100% groups were similar and significantly lower in relation to that of DFF and ADF50% groups (p < 0.01). Measurements of area under the curve in GTT and ITT revealed that the ADF100% group was more insulin-sensitive than the DFF and ADF50% groups. In conclusion, these data suggest that the ADF100% improves fructose-induced insulin resistance in mice.

Haplotypes across the human caveolin 1 gene upstream purine complex significantly alter gene expression: implication in neurodegenerative disorders

We have previously reported a polymorphic purine complex at the 1.5 kb upstream region of the human caveolin 1 (CAV1) gene that is conserved across several species in respect with sequence motifs and the location of the complex. The IRF and Ets transcription factors have common binding sites for this region across those species. We have also shown skew in the homozygote haplotype compartment of this complex in two neurodegenerative disorders, sporadic late-onset Alzheimer's disease (AD), and multiple sclerosis (MS), versus disease-free controls (p<0.0000001). In the current study, we analyze the functional implication of the disease homozygote haplotypes (i.e. 102-bp and 142-bp) vs. control homozygote haplotype (110-bp) in three neuronal cell lines, LAN-5, U-87 MG, and N2A, using dual luciferase reporter system. A significant increase in gene expression was observed in the cell lines with the disease haplotype constructs vs. control haplotype in the three cell lines (t-test p<4 × 10(-4), 1 × 10(-6), and 3 × 10(-4)), respectively. We conclude that the human CAV1 upstream purine complex modifies gene expression. An additive effect of the haplotypes in the homozygous status is speculated based on the skew in the homozygote haplotypes in neurodegenerative disorders.