ANGPTL8/Betatrophin Improves Glucose Tolerance in Older Mice and Metabolomic Analysis Reveals Its Role in Insulin Resistance in HepG2 Cells

Abstract

Background: Insulin resistance is a determining factor in the pathophysiology of type 2 diabetes mellitus (T2DM). Angiopoietin-like protein 8 (ANGPTL8, also known as betatrophin), associated with glucose homeostasis and lipid metabolism, has attracted attention. But its mechanism in glucose metabolism remains unclear. This study aimed to explore the effect of ANGPTL8/betatrophin on glucose tolerance in Kunming (KM) mice of different ages and metabolic profiles in insulin-resistant HepG2 cells. Our study may provide a new perspective of ANGPTL8/betatrophin in insulin resistance from the metabolic changes. Methods: Oral glucose tolerance test was performed in KM mice of different ages. Insulin concentration was measured by using a quantitative enzyme-linked immunosorbent assay (ELISA). ANGPTL8/betatrophin knockouts in HepG2 cells were established with clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) protein 9 (CRISPR/Cas9) system. Cell counting kit-8 (CCK-8) assay was used to determine cell viability after gene knockout. The effect of ANGPTL8/betatrophin on the metabolomic changes was evaluated in high insulin-induced insulin-resistant HepG2 cells by an ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method. Results: ANGPTL8/betatrophin improved glucose tolerance in older mice not by altering the concentration of insulin. Cell growth was affected in ANGPTL8/betatrophin knockout HepG2. Based on UPLC-MS/MS, compared with wild type insulin-resistant HepG2 cells, we identified 83 differential metabolites in ANGPTL8/betatrophin knockout HepG2 cells after high insulin induction. Among the 14 differential up-regulated metabolites, D-mannose had the highest fold change. In insulin-resistant HepG2 cells, ANGPTL8/betatrophin knockout exerted an effect on the amino acid metabolism, carbohydrate metabolism, metabolism of cofactors and vitamins, lipid metabolism, nucleotide metabolism, and genetic information processing pathway. Conclusion:This study identified the effect of ANGPTL8/betatrophin on glucose tolerance in mice of different ages and metabolic profiles in insulin-resistant HepG2 cells. These findings may contribute to a new understanding of its role in glucose metabolism in the context of insulin resistance.

Angiopoietin-Like 8 in Gestational Diabetes Mellitus: Reduced Levels in Third Trimester Maternal Serum and Placenta, Increased Levels in Cord Blood Serum

“…Increased maternal serum ANGPTL8 levels were observed in pregnant women relative to non-pregnancy women, which was consistent with the findings of Trebotic et al [ 22 ]. However, the current study showed a decreased level of ANGPTL8 in GDM group compared with NGT group, which was inconsistent with the results from Huang et al [ 11 ] and Erol et al [ 12 ].…”

“…The population difference (Turkish vs. Chinese) may also contribute to the differences observed in Erol et al Interestingly, reduced placental ANGPTL8 protein expression was observed for the first time in GDM patients compared to NGT pregnant women. Since ANGPTL8 is known to reduce maternal serum TG levels [ 23 ] and improve glucose tolerance [ 22 ], the increased circulating ANGPTL8 levels in NGT objects may be a compensation to pregnancy-induced metabolic changes, while the GDM patients may have entered a decompensated state in ANGPTL8 synthesis. The placenta plays many important roles during pregnancy, including maintaining normal fetal physiology and protecting the fetus, as well as providing oxygen and nutrients for fetal development and growth [ 1 ].…”

The predictive diagnosis for ANGPTL8 level in women with T2DM

“…The results are presented in table.1, for demographic data in controls and T2DM patients, showed a nonsignificant difference (p-value = 0.185 and 0.288) in age and BMI in patients compared with a control. In the current research, our data that values are given in Table 1, are agreement with other studies in T2DM group as compared with controls [1], [11], [15].…”

“…ANGPTL8 levels in the blood were found to be significantly higher in patients than in control subjects [10]. Other studies have also found that ANGPTL8 levels are increased in patients with T2DM [2], [11]- [16]. Furthermore, in patients, several studies have found a link between blood glucose, (HOMA-IR), and ANGPTL8 [12], [17].…”

“…A significant increase (p<0.0001) in table. ANGPTL8 levels in the blood has been studied in the T2DM patients in the past, however, the results have been mixed [11], [21], [24]. ANGPTL8 levels in a female with T2DM was found to be constant in some investigations, while they were shown to be elevated or lowered in others [25], [26].…”