ESCRT recruitment by the inner nuclear membrane protein Heh1 is regulated by Hub1-mediated alternative splicing

Abstract

Deceased during the course of this studyRunning title:HEH1 splicing controls NE integrity ORCID Capella: https://orcid.org/0000-0003-4804-243X ORCID Martín Caballero: https://orcid.org/0000-0001-7139-5992 ORCID Pfander: https://orcid.org/0000-0003-2180-5054 ORCID Braun: https://orcid.org/0000-0001-6399-8574 § Summary statementHeh1-S, the Hub1-mediated spliced version of HEH1 pre-mRNA, contributes to nuclear envelope maintenance by preventing excessive recruitment of Chm7.3 AbstractMisassembled nuclear pore complexes (NPCs) are removed by sealing off the surrounding nuclear envelope (NE), which is mediated by members of the ESCRT (endosomal sorting complexes required for transport) machinery. Recruitment of ESCRT proteins to the NE is mediated by the interaction between the ESCRT member Chm7 and the inner nuclear membrane protein Heh1, which belongs to the conserved LEM family. Increased ESCRT recruitment results in excessive membrane scission at damage sites but its regulation remains poorly understood. Here, we show that Hub1mediated alternative splicing of HEH1 pre-mRNA, resulting into its shorter form Heh1-S, is critical for the integrity of the NE. ESCRT-III mutants lacking Hub1 or Heh1-S display severe growth defects and accumulate improperly assembled NPCs. This depends on the interaction of Chm7 with the conserved MSC domain only present in the longer spliced variant Heh1-L. Heh1 variants assemble into heterodimers and we demonstrate that a unique splice segment in Heh1-S suppresses growth defects associated with uncontrolled interaction between Heh1-L and Chm7. Together, our findings reveal that Hub1-mediated splicing generates Heh1-S to regulate ESCRT recruitment to the nuclear envelope. , E., Lin, F., Braud, S., Gondry, M., Gilquin, B., Worman, H. J. and Zinn-Justin S. (2006). The carboxyl-terminal nucleoplasmic region of MAN1 exhibits a DNA binding winged helix domain. et al. (2016). A global genetic interaction network maps a wiring diagram of cellular function. Science 353, aaf1420. Cronshaw, J. M., Krutchinsky, A. N., Zhang, W., Chait, B. T. and Matunis, M. J. (2002). Proteomic analysis of the mammalian nuclear pore complex. J. Cell Biol. 158, 915-927. D'Angelo, M. A. and Hetzer, M. W. (2008). Structure, dynamics and function of nuclear pore complexes.