A link between endoplasmic reticulum stress-induced β-cell apoptosis and the group VIA Ca2+-independent phospholipase A2 (iPLA2β)

Endoplasmic reticulum (ER) stress is becoming recognized as an important contributing factor in various diseases, including diabetes mellitus. Prolonged ER stress can cause β-cell apoptosis; however, the underlying mechanism(s) that contribute to this process are not well understood. Early reports suggested that arachidonic acid metabolites and a Ca2+-independent phospholipase A2 (iPLA2) activity play a role in β-cell apoptosis. The PLA2 family of enzymes catalyse the hydrolysis of the sn-2 substituent (i.e. arachidonic acid) of membrane phospholipids. In light of our findings that the pancreatic islet β-cells are enriched in arachidonate-containing phospholipids and express the group VIA iPLA2β, we considered the possibility that iPLA2β participates in ER stress-induced β-cell apoptosis. Our work revealed a novel mechanism, involving ceramide generation and triggering of mitochondrial abnormalities, by which iPLA2β participates in the β-cell apoptosis process. Here, we review our evidence linking ER stress, β-cell apoptosis and iPLA2β. Continued studies in this area will increase our understanding of the contribution of iPLA2β to the evolution of diabetes mellitus and will further our knowledge of factors that influence β-cell health in diabetes mellitus and identify potential targets for future therapeutic interventions to prevent β-cell death.