The regulatory subunits of PI3K, p85α and p85β, interact with XBP-1 and increase its nuclear translocation

Insulin can signal through phosphotidylinositol 3-kinase (PI3K) to increase cellular growth, which often results in increased protein translation and stress of the endoplasmic reticulum (ER). Umut Ozcan and his colleagues now find that insulin signaling leads to the disassociation of p85α and p85β, the heterodimeric regulatory subunits of PI3K, allowing them to interact with and increase the nuclear localization of a key transcription factor that resolves ER stress. Thus, in states of insulin resistance, such as in prediabetes, resolution of ER stress is hampered, further exacerbating the disease (pages 374–376 and 438–445).