X-box binding protein 1 (XBP1)

The X-box binding protein 1 (XBP1) is a bZIP-domain-containing transcription factor that orchestrates key aspects of immune regulation and cellular adaptation to endoplasmic reticulum stress through its unique mechanism involving regulated RNA splicing. It exists in two main isoforms: an unspliced form (XBP1u) and a spliced form (XBP1s), with XBP1s being the active transcription factor produced during ER stress. XBP1s upregulates genes involved in protein folding, ER-associated degradation, and lipid biosynthesis, and is essential for plasma cell differentiation and proper immune system function. Dysregulation of XBP1 can lead to impaired immune responses, defective antibody secretion, and involvement in diseases such as sepsis-induced acute kidney injury.

Other names

XBP-1

XBP1s binds cis-regulatory elements on target gene promoters involved in restoring proteostasis within the secretory pathway after unconventional splicing of Xbp1 mRNA mediated by IRE1.