Involvement of 4E-BP1 in the Protection Induced by HDLs on Pancreatic β-Cells

High-density lipoproteins (HDLs) protect pancreatic β-cells against apoptosis. This property might relate to the increased risk to develop diabetes in patients with low HDL blood levels. However, the mechanisms by which HDLs protect β-cells are poorly characterized. Here we used a transcriptomic approach to identify genes differentially modulated by HDLs in β-cells subjected to apoptotic stimuli. The transcript encoding 4E-binding protein (4E-BP)1 was up-regulated by serum starvation, and HDLs blocked this increase. 4E-BP1 inhibits cap-dependent translation in its non- or hypophosphorylated state but it loses this ability when hyperphosphorylated. At the protein level, 4E-BP1 was also up-regulated in response to starvation and IL-1β, and this was blunted by HDLs. Whereas an ectopic increase of 4E-BP1 expression induced β-cell death, silencing 4E-BP1 increase with short hairpin RNAs inhibited the apoptotic-inducing capacities of starvation. HDLs can therefore protect β-cells by blocking 4E-BP1 protein expr...