OBJECTIVE: Obesity is a chronic disease with high incidence worldwide, which promotes the risk of incidence of type 2 diabetes (T2D). Obesity-induced adipocyte expansion promotes local chronic inflammation in the adipose tissue which is considered a contributing factor to insulin resistance, hyperinsulinemia, and T2D. Many organs, including adipose tissue, involve in the dysregulation of glucose homeostasis in T2D. The crosstalk between adipose tissue/adipocytes and pancreatic ß-cells has provoked scientists' interest for years. Here in this thesis, we focused on the effect carried out by adipocyte-specific GPS2 depletion on insulin secretion from pancreatic ß-cells.
METHODS: Conditioned media collected over 24 h from both primary adipocyte and adipose tissue explant cultures from high fat diet (HFD)-fed WT and adipocyte-specific GPS2 knock-out (GPS2-AKO) mice were used to treat INS-1 clonal pancreatic ß-cells or primary islets from chow-diet WT mice. Conditioned media was diluted 1:8 in culture media of clonal INS-1 cells (cultured in media with 4 mM or 11 mM glucose chronically) and primary islets (cultured in media with 11 mM glucose) and incubated for 18 h before measuring insulin secretion. The isolated islets from chow-diet WT mice were also be treated with the primary adipocytes conditioned media from eWAT (epididymal white adipose tissue) of HFD-fed WT and GPS2-AKO mice. In addition, the effect of exosomes extracted from primary adipocyte conditioned media of HFD-fed WT and GPS2-AKO mice on GSIS was investigated in clonal INS-1 cells. Glucose-stimulated insulin secretion (GSIS) was measured to assess differences in insulin secretion by INS-1 cells and islets from mice in response to signaling from WT or GPS2-AKO adipocytes.
RESULTS: Adipocyte conditioned media from both WT and GPS2-AKO mice reduced GSIS from INS-1 cells by the same extent compared to a non-treated control. The same result was obtained using media conditioned by adipose tissue explant culture. Exosomes isolated from adipocyte conditioned media from both WT and GPS2-AKO mice also reduced GSIS from INS-1 cells with no significant difference between WT and GPS2-AKO. Islets isolated from chow-diet WT mice treated with adipocyte conditioned media from eWAT of WT and GPS2-AKO mice also showed no significant difference between WT and GPS2-AKO in GSIS compared to our non-treated control.
CONCLUSIONS: Both conditioned media and exosomes from primary adipocytes of HFD-fed mice inhibits GSIS from INS-1 cells and isolated islets, but no difference was observed between WT and GPS2-AKO mice. We conclude that the deletion of GPS2 in adipocytes does not influence GSIS from pancreatic ß-cells under our experimental conditions. Conditioned media-induced inhibition of GSIS is mediated by factors that may contribute to adipocyte-ß-cell crosstalk in-vivo. / 2025-11-02T00:00:00Z
| Identifer | oai:union.ndltd.org:bu.edu/oai:open.bu.edu:2144/47451 |
| Date | 03 November 2023 |
| Creators | Fan, Ting-Yu |
| Contributors | Perissi, Valentina, Deeney, Jude T. |
| Source Sets | Boston University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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