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Saponins of Momordica charantia increase insulin secretion in INS-1 pancreatic β-cells via the PI3K/Akt/FoxO1 signaling pathway.

Authors
  • Liu, Yufan1
  • Mu, Shumin2
  • Chen, Wenbin3
  • Liu, Shiyin4
  • Cong, Yuxuan5
  • Liu, Jiajia6
  • Jia, Ning7
  • 1 Traditional Chinese Medicine College, Shandong University of Traditional Chinese Medicine, Jinan, China. , (China)
  • 2 Department of Endocrinology, Hospital Affiliated to Shandong Traditional Chinese Medicine University, Jinan, China. Electronic address: [email protected] , (China)
  • 3 Scientific Center, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, China. , (China)
  • 4 First Medical College, Shandong University of Traditional Chinese Medicine, Jinan, China. , (China)
  • 5 Department of Endocrinology, Weihai Hospital of Traditional Chinese Medicine, Weihai, China. , (China)
  • 6 Department of Endocrinology, People's Hospital of Gaotang County, Liaocheng, China. , (China)
  • 7 Department of Traditional Chinese Medicine, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, China. , (China)
Type
Published Article
Journal
Endocrinologia, diabetes y nutricion
Publication Date
May 01, 2021
Volume
68
Issue
5
Pages
329–337
Identifiers
DOI: 10.1016/j.endinu.2020.05.005
PMID: 33069631
Source
Medline
Keywords
Language
Spanish
License
Unknown

Abstract

Saponins are the main bioactive substances with anti-hyperglycemic activities of Momordica charantia. This study aimed to verify the effects of M. charantia saponins on insulin secretion and explore the potential underlying mechanisms in INS-1 pancreatic β-cells. We injured INS-1 cells with 33.3mM glucose and then treated them with saponins. Saponins improved cell morphology and viability as demonstrated by inverted microscopy and CCK8 detection and significantly increased insulin secretion in a concentration-dependent manner as shown by ELISA. Thus, we obtained the optimal concentration for the subsequent experiments. Potential mechanisms were explored by immunofluorescence, western blotting, and RT-qPCR techniques. First, saponins increased the mRNA and protein levels of IRS-2 but decreased the serine 731 phosphorylation level of IRS-2. Moreover, saponins increased the phosphorylation of Akt protein and decreased the protein level of FoxO1, which were both reversed by the PI3K inhibitor ly294002. Furthermore, saponins increased the protein level of the downstream molecule and insulin initiating factor PDX-1, which was also reversed by ly294002. Saponins also increased Akt and PDX-1 mRNA and decreased FoxO1 mRNA, which were both reversed by ly294002. Saponins increased glucose-stimulated insulin secretion (GSIS) and intracellular insulin content, which were reversed by ly294002, as determined by ELISA. The immunofluorescence results also confirmed this tendency. In conclusion, our findings improve our understanding of the function of saponins in INS-1 pancreatic β-cells and suggest that saponins may increase insulin secretion via the PI3K/Akt/FoxO1 signaling pathway. Copyright © 2020 SEEN y SED. Publicado por Elsevier España, S.L.U. All rights reserved.

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