Overexpression of miR-297b-5p in Mouse Insulin-Secreting Cells Promotes Metformin-Mediated Protection Against Stearic Acid-Induced Senescence by Targeting Igf1r

Overexpression of miR-297b-5p in Mouse Insulin-Secreting Cells Promotes Metformin-Mediated Protection Against Stearic Acid-Induced Senescence by Targeting Igf1r

Qingrui Zhao^1,†, Shenghan Su^1,†, Yuqing Lin^1,†, Xuebei Li¹, Lingfeng Dan¹, Chunxiao Yang¹, Chenchen Geng¹, Romano Regazzi^2,3, Xiaohan Li¹, Yimeng Dong¹, Changhao Sun¹, Xia Chu^1,*, Huimin Lu^1,2,*

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¹ Department of Nutrition and Food Hygiene (National Key Discipline), Public Health College, Harbin Medical University, 150081 Harbin, Heilongjiang, China

² Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne, Switzerland

³ Department of Biomedical Sciences, University of Lausanne, 1005 Lausanne, Switzerland

^*Correspondence: lhm_519@sina.com (Huimin Lu); cx831128@163.com (Xia Chu)
^†These authors contributed equally.

Front. Biosci. (Landmark Ed) 2023, 28(8), 181; https://doi.org/10.31083/j.fbl2808181

Submitted: 9 March 2023 | Revised: 19 April 2023 | Accepted: 24 May 2023 | Published: 28 August 2023

This is an open access article under the CC BY 4.0 license.

Abstract

Background: A long-term consumption of saturated fat significantly increases the concentration of saturated fatty acids in serum, which accelerates the appearance of senescence markers in $\beta{}$ -cells and leads to their dysfunction. An understanding of the mechanisms underlying $\beta{}$ -cell senescence induced by stearic acid and the exploration of effective agents preventing it remains largely unclear. Here, we aimed to investigate the protective effect of metformin against stearic acid-treated $\beta{}$ -cell senescence and to assess the involvement of miR-297b-5p in this process. Methods: To identify senescence, we measured senescence-associated $\beta{}$ -galactosidase activity and the expression of senescence-related genes. Gain and loss of function approaches were applied to explore the role of miR-297b-5p in stearic acid-induced $\beta{}$ -cell senescence. Bioinformatics analysis and a luciferase activity assay were used to predict the downstream targets of miR-297b-5p. Results: Stearic acid markedly induced senescence and suppressed miR-297b-5p expression in mouse $\beta{}$ -TC6 cells, which were significantly alleviated by metformin. After transfection of miR-297b-5p mimics, stearic acid-evoked $\beta{}$ -cell senescence was remarkably prevented. Insulin-like growth factor-1 receptor was identified as a direct target of miR-297b-5p. Inhibition of the insulin-like growth factor-1 receptor prevented stearic acid-induced $\beta{}$ -cell senescence and dysfunction. Moreover, metformin alleviates the impairment of the miR-297b-5p inhibitor in $\beta{}$ -TC6 cells. Additionally, long-term consumption of a high-stearic-acid diet significantly increased senescence and reduced miR-297b-5p expression in mouse islets. Conclusions: These findings imply that metformin alleviates $\beta{}$ -cell senescence by stearic acid through upregulating miR-297b-5p to suppress insulin-like growth factor-1 receptor expression, thereby providing a potential target to not only prevent high fat-diet-induced $\beta{}$ -cell dysfunction but also for metformin therapy in type 2 diabetes.

Keywords

stearic acid

β-cell senescence

miRNA

metformin

type 2 diabetes

Funding

YQ2020H033/Excellent Youth Foundation of Heilongjiang Province of China

82273614/National Natural Science Foundation of China

China Scholarship Council

Figures

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Fig. 1.

Metformin protects against stearic acid-induced senescence in mouse $\beta{}$ -TC6 cells. (A) Cytotoxic effect of metformin on the survival rate of $\beta{}$ -TC6 cells at various concentrations (0, 12.5, 25, 50, 100, 200, 400, 800, 1600, 3200, 6400, and 12800 µmol/L). ${}^{*}$ p $<$ 0.05, ${}^{**}$ p $<$ 0.01, ${}^{***}$ p $<$ 0.001 vs. 0 mmol/L group. (B) Cytotoxic effect of 50 µmol/L metformin on $\beta{}$ -cell viability at various times (0, 6, 12, 24, and 48 h). ${}^{*}$ p $<$ 0.05 vs. 0 h group. (C,D) Protective effect of metformin on the cell survival rate and glucose-stimulated insulin secretion in stearic acid-treated $\beta{}$ -TC6 cells. (E) Changes in expression of senescence-related genes after treatment of $\beta{}$ -TC6 cells with metformin in the presence or absence of stearic acid. (F) Effect of metformin on $\beta{}$ -galactosidase activity with or without stearic acid treatment. (G) Immunofluorescence analysis shows the expression of insulin-like growth factor-1 receptor (IGF1R) in $\beta{}$ -TC6 cells treated with metformin in the presence or absence of stearic acid. Hoechst, blue; IGF1R, red. For C–G, ${}^{*}$ p $<$ 0.05, ${}^{**}$ p $<$ 0.01, ${}^{***}$ p $<$ 0.001 vs. Ctrl group; ${}^{\textasciicircum{}}$ p $<$ 0.05, ${}^{\textasciicircum{}\textasciicircum{}}$ p $<$ 0.01, ${}^{\textasciicircum{}\textasciicircum{}\textasciicircum{}}$ p $<$ 0.001 vs. SA group. Ctrl, control group; SA, stearic acid; Met, metformin. For F and G, scale bar: 100 µm. Each independent experiment was repeated three times.

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