New Roles of bZIP-Containing Membrane-Bound Transcription Factors in Chromatin Tethering and Karyoptosis.

The nuclear membrane has emerged as a dynamic regulatory platform coordinating genome organization, mechanotransduction, and regulated cell death (RCD). Beyond its barrier function, the nuclear skeleton-comprising lamins, actin-myosin isoforms, nuclear matrix proteins, and the LINC complex-supports nuclear integrity and gene regulation. Recent evidence shows that type II membrane-bound bZIP transcription factors such as cAMP-responsive element-binding protein 3 (CREB3) and CREB3L1 localize to the inner nuclear membrane (INM), linking chromatin tethering with stress signaling. Their stress-induced cleavage by S1P/S2P disrupts chromatin anchoring and, in some contexts, triggers karyoptosis, a novel form of RCD defined by nuclear rupture. These findings position the nuclear envelope (NE) as a mechanosensitive signaling hub with direct implications for disease and therapy. In this review, we provide a comprehensive discussion on how type II membrane-bound bZIP transcription factors and chromatin acting as a nucleoskeleton cooperate to regulate nuclear membrane integrity.