Arachidonic acid and lysophosphatidylcholine inhibit multiple late steps of regulated exocytosis

The Roles of Phospholipase A2 in Phagocytes

“…Similar results were also obtained in homotypic fusion of cortical vesicles isolated from eggs of the sea urchin, in which increasing the LPC concentrations in the outer leaflets of these vesicles by external LPC blocked fusion (Dabral and Coorssen, 2019). However, the PLA 2 products might not only affect the membrane fusion, but also upstream events as the external application of ARA also affected the SNARE dependent docking or priming in homotypic fusion of cortical vesicles (Dabral and Coorssen, 2019). Because many SNARE proteins are both functionally and structurally homologous, and since many SNARE proteins are involved in endosomal trafficking and phagocytosis (Dingjan et al, 2018), similar interactions with PLA 2 metabolites could potentially inhibit or promote membrane fusion in phagocytosis as well.…”

“…In contrast, the intracellular administration of LPC and oleic acid by microinjection, which increased their concentration in the inner leaflet of the plasma membrane, blocked and promoted membrane fusion, respectively ( Dhara et al, 2020 ). Similar results were also obtained in homotypic fusion of cortical vesicles isolated from eggs of the sea urchin, in which increasing the LPC concentrations in the outer leaflets of these vesicles by external LPC blocked fusion ( Dabral and Coorssen, 2019 ). However, the PLA 2 products might not only affect the membrane fusion, but also upstream events as the external application of ARA also affected the SNARE dependent docking or priming in homotypic fusion of cortical vesicles ( Dabral and Coorssen, 2019 ).…”

Lipid nanoparticles with erythrocyte cell-membrane proteins

“…On the other hand, these ''biosurfactants" are natural metabolites, with important roles as markers in connection with several diseases [17]. They can interact with receptors as well as enzymes and can cause alterations in cellmechanisms [18][19][20]. Here we show that lysophospholipids easily associate with proteins and can collect the solubilized proteins, which might be used as a useful alternative approach when handling protein-containing systems.…”

Unbiased Thiol-Labeling and Top-Down Proteomic Analyses Implicate Multiple Proteins in the Late Steps of Regulated Secretion

“…This Rab family 1 motif is largely conserved (>50%) among the Rab GTPases and across different species (Table 2), and this effector domain peptide has been previously shown to interfere with the formation of the fertilization envelope in urchin oocytes [47]. An addition of exogenous RAB peptide inhibited the extent of fusion by~63% in the modified settle assay, compared to~46% in the standard assay; this strongly indicates an effect on upstream stages of CV tethering/docking/priming [1][2][3]6,8,30,39]. With the addition of the RAB effector domain, there was no effect on Ca 2+ -sensitivity; however, after pretreatment with IA, treatment with the RAB peptide resulted in a decrease in Ca 2+ -sensitivity, mitigating the potentiation effect of IA.…”

“…This involves the coordinated actions of both lipid and protein components of the secretory vesicle membrane, particularly the later steps of Ca 2+ -triggered exocytosis. There have been recent advances in understanding how the lipid matrix may modulate upstream docking/priming steps [1][2][3][4][5][6][7], regulate the Ca 2+ sensitivity and efficiency of fusion [5][6][7][8][9][10][11], and facilitate or impede the merger of biological membranes [1,6,7,9,[12][13][14]. However, there remains debate regarding the identity of proteins involved in the Ca 2+ -sensing and triggering steps that regulate the efficiency of exocytosis.…”