β cell membrane remodelling and procoagulant events occur in inflammation‐driven insulin impairment: a GLP‐1 receptor dependent and independent control

Abstract

Inflammation and hyperglycaemia are associated with a prothrombotic state. Cell‐derived microparticles (MPs) are the conveyors of active procoagulant tissue factor (TF) and circulate at high concentration in diabetic patients. Liraglutide, a glucagon‐like peptide (GLP)‐1 analogue, is known to promote insulin secretion and β‐cell preservation. In this in vitro study, we examined the link between insulin impairment, procoagulant activity and plasma membrane remodelling, under inflammatory conditions. Rin‐m5f β‐cell function, TF activity mediated by MPs and their modulation by 1 μM liraglutide were examined in a cell cross‐talk model. Methyl‐β‐cyclodextrine (MCD), a cholesterol depletor, was used to evaluate the involvement of raft on TF activity, MP shedding and insulin secretion as well as Soluble N‐éthylmaleimide‐sensitive‐factor Attachment protein Receptor (SNARE)‐dependent exocytosis. Cytokines induced a two‐fold increase in TF activity at MP surface that was counteracted by liraglutide. Microparticles prompted TF activity on the target cells and a two‐fold decrease in insulin secretion via protein kinase A (PKA) and p38 signalling, that was also abolished by liraglutide. Large lipid raft clusters were formed in response to cytokines and liraglutide or MCD‐treated cells showed similar patterns. Cells pre‐treated by saturating concentration of the GLP‐1r antagonist exendin (9‐39), showed a partial abolishment of the liraglutide‐driven insulin secretion and liraglutide‐decreased TF activity. Measurement of caspase 3 cleavage and MP shedding confirmed the contribution of GLP‐1r‐dependent and ‐independent pathways. Our results confirm an integrative β‐cell response to GLP‐1 that targets receptor‐mediated signalling and membrane remodelling pointing at the coupling of insulin secretion and inflammation‐driven procoagulant events.

Endothelial microparticles released by activated protein C protect beta cells through EPCR/PAR1 and annexin A1/FPR2 pathways in islets

“…Rin‐m5f rat insulin‐secreting cells were chosen as an adequate model for the study of the β cell response to prolonged oxidative stress and hyperglycaemia. Indeed, although not responsive to a short metabolic raise by glucose stimulation, Rin‐m5f develop apoptosis after prolonged exposure to H 2 O 2 .…”

Activation of microglial GLP-1R in the trigeminal nucleus caudalis suppresses central sensitization of chronic migraine after recurrent nitroglycerin stimulation

“…Cells were incubated with serum-free media for 24 h prior to each experiment and seeded at 1 × 10 6 cells/dish in 100 mm culture dishes for western blotting and 3 × 10 4 cells/well in 24-well-culture plates for immunofluorescence. To study the role of GLP-1R in microglial inflammation, BV-2 cells were preincubated with the selective GLP-1R agonist liraglutide (100 nM, Selleck, TX, USA) and the antagonist exendin(9-39) (200 nM, MCE, USA) for 24 h, followed by LPS (1 µg/ml, Sigma-Aldrich, MO, USA) stimulation for 24 h. The doses of these drugs used with cells were based on previous data [34][35][36].…”

Conventional and Unconventional Mechanisms by which Exocytosis Proteins Oversee β-cell Function and Protection

“…GLP-1 stimulates PKA-dependent phosphorylation of synaptotagmin-7, a crucial Ca 2+ sensor affiliated with SNARE-mediated exocytosis, thereby boosting glucose- and Ca 2+ -stimulated insulin secretion [ 123 ]. Liraglutide, a GLP-1 analog, was reported to modulate plasma membrane-raft clustering in RIN-m5f β-cells, possibly impacting functionality of raft-embedded SNARE protein isoforms STX1, SNAP25, and VAMP2 [ 124 ]. Indeed, earlier studies showed GLP-1 to enhance insulin secretion via mobilizing and docking an increased number of ISGs at the plasma membrane and accelerating sequential ISG—ISG fusions [ 118 ].…”