Individual and combined effects of GIP and xenin on differentiation, glucose uptake and lipolysis in 3T3-L1 adipocytes

Research output: Contribution to journalArticle

Abstract

The incretin hormone glucose-dependent insulinotropic polypeptide (GIP), released postprandially from K-cells, has established actions on adipocytes and lipid metabolism. In addition, xenin, a related peptide hormone also secreted from K-cells after a meal, has postulated effects on energy regulation and lipid turnover. The current study has probed direct individual and combined effects of GIP and xenin on adipocyte function in 3T3-L1 adipocytes, using enzyme-resistant peptide analogues, (D-Ala2)GIP and xenin-25-Gln, and knockdown (KD) of receptors for both peptides. (D-Ala2)GIP stimulated adipocyte differentiation and lipid accumulation in 3T3-L1 adipocytes over 96h, with xenin-25-Gln evoking similar effects. Combined treatment significantly countered these individual adipogenic effects. Individual receptor KD impaired lipid accumulation and adipocyte differentiation, with combined receptor KD preventing differentiation. (D-Ala2)GIP and xenin-25-Gln increased glycerol release from 3T3-L1 adipocytes, but this lipolytic effect was significantly less apparent with combined treatment. Key adipogenic and lipolytic genes were upregulated by (D-Ala2)GIP or xenin-25-Gln, but not by dual peptide culture. Similarly, both (D-Ala2)GIP and xenin-25-Gln stimulated insulin-induced glucose uptake in 3T3-L1 adipocytes, but this effect was annulled by dual treatment. In conclusion, GIP and xenin possess direct, comparable, lipogenic and lipolytic actions in 3T3-L1 adipocytes. However, effects on lipid metabolism are significantly diminished by combined administration.
Original languageEnglish
Pages (from-to)xx
JournalBiological Chemistry
DOIs
Publication statusAccepted/In press - 4 Aug 2020

Keywords

  • 3T3-L1 adipocytes
  • differentiation
  • glucose-dependent insulinotropic polypeptide (GIP)
  • 3glucose uptake
  • lipid metabolism
  • xenin

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