RRC ID 80878
Author Barger SR, Penfield L, Bahmanyar S.
Title Nuclear envelope assembly relies on CHMP-7 in the absence of BAF-LEM-mediated hole closure.
Journal J Cell Sci
Abstract Barrier-to-autointegration factor (BAF) protein is a DNA-binding protein that crosslinks chromatin to allow mitotic nuclear envelope (NE) assembly. The LAP2-emerin-MAN1 (LEM)-domain protein LEMD2 and ESCRT-II/III hybrid protein CHMP7 close NE holes surrounding spindle microtubules (MTs). BAF binds LEM-domain family proteins to repair NE ruptures in interphase, but whether BAF-LEM binding participates in NE hole closure around spindle MTs is not known. Here, we took advantage of the stereotypical event of NE formation in fertilized Caenorhabditis elegans oocytes to show that BAF-LEM binding and LEM-2-CHMP-7 have distinct roles in NE closure around spindle MTs. LEM-2 and EMR-1 (homologs of LEMD2 and emerin) function redundantly with BAF-1 (the C. elegans BAF protein) in NE closure. Compromising BAF-LEM binding revealed an additional role for EMR-1 in the maintenance of the NE permeability barrier. In the absence of BAF-LEM binding, LEM-2-CHMP-7 was required for NE assembly and embryo survival. The winged helix domain of LEM-2 recruits CHMP-7 to the NE in C. elegans and a LEM-2-independent nucleoplasmic pool of CHMP-7 also contributes to NE stability. Thus, NE hole closure surrounding spindle MTs requires redundant mechanisms that safeguard against failure in NE assembly to support embryogenesis.
Volume 136(21)
Published 2023-11-1
DOI 10.1242/jcs.261385
PII 330780
PMID 37795681
PMC PMC10668030
MeSH Animals Caenorhabditis elegans* / genetics Caenorhabditis elegans* / metabolism Cell Nucleus / metabolism Nuclear Envelope* / metabolism Nuclear Proteins / genetics Nuclear Proteins / metabolism
C.elegans tm1582 tm3468