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Published March 14, 2017 | Published + Submitted + Supplemental Material
Journal Article Open

LEM2 recruits CHMP7 for ESCRT-mediated nuclear envelope closure in fission yeast and human cells

Abstract

Endosomal sorting complexes required for transport III (ESCRT-III) proteins have been implicated in sealing the nuclear envelope in mammals, spindle pole body dynamics in fission yeast, and surveillance of defective nuclear pore complexes in budding yeast. Here, we report that Lem2p (LEM2), a member of the LEM (Lap2-Emerin-Man1) family of inner nuclear membrane proteins, and the ESCRT-II/ESCRT-III hybrid protein Cmp7p (CHMP7), work together to recruit additional ESCRT-III proteins to holes in the nuclear membrane. In Schizosaccharomyces pombe, deletion of the ATPase vps4 leads to severe defects in nuclear morphology and integrity. These phenotypes are suppressed by loss-of-function mutations that arise spontaneously in lem2 or cmp7, implying that these proteins may function upstream in the same pathway. Building on these genetic interactions, we explored the role of LEM2 during nuclear envelope reformation in human cells. We found that CHMP7 and LEM2 enrich at the same region of the chromatin disk periphery during this window of cell division and that CHMP7 can bind directly to the C-terminal domain of LEM2 in vitro. We further found that, during nuclear envelope formation, recruitment of the ESCRT factors CHMP7, CHMP2A, and IST1/CHMP8 all depend on LEM2 in human cells. We conclude that Lem2p/LEM2 is a conserved nuclear site-specific adaptor that recruits Cmp7p/CHMP7 and downstream ESCRT factors to the nuclear envelope.

Additional Information

© 2017 National Academy of Sciences. Freely available online through the PNAS open access option. Edited by Pietro De Camilli, Yale University and Howard Hughes Medical Institute, New Haven, CT, and approved January 30, 2017 (received for review August 19, 2016). Published ahead of print February 27, 2017. We thank Drs. Brian Dalley and Tim Parnell for advice and expertise in whole-genome sequencing and analysis; Dr. Janet Iwasa for graphic illustration; Dr. Mark Smith for assistance with confocal microscopy; Sarah M. Pick for technical assistance with protein purification; Dr. Doug Mackay for advice; Dr. Shelley Sazer for a NLS-GFP-LacZ nuclear integrity reporter; Dr. Yasushi Hiraoka for an Ish1-GFP strain; and Drs. John McCullough, Jeremy Carlton, and Patrick Lusk for stimulating conversations about unpublished results. Light and 2D transmission electron microscopy were performed in the Health Sciences Cores at the University of Utah. Microscopy equipment was obtained by using NCRR Shared Equipment Grant 1S10-RR024761-01. Our research was also supported by the Searle Scholars Program (A.F.); NIH Grants 2P50-GM082545-06 (to W.I.S., A.F., M.S.L., and P.J.B.), 1DP2-GM110772-01 (to A.F.), and 1R01-GM112080 (to W.I.S.); and Huntsman Cancer Foundation and the Huntsman Cancer Institute Cancer Center Support Grant NIH P30CA042014 (to K.S.U., W.I.S., A.F., and the Genomics and Bioinformatics Shared Resource). Author contributions: M.G., D.L., O.S.C., A.v.A., W.I.S., K.S.U., and A.F. designed research; M.G., D.L., O.S.C., A.v.A., M.S.L., M.J.R., and L.N. performed research; P.J.B. contributed new reagents/analytic tools; M.G., D.L., O.S.C., A.v.A., M.S.L., W.I.S., K.S.U., and A.F. analyzed data; and M.G., D.L., O.S.C., A.v.A., W.I.S., K.S.U., and A.F. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission. This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1613916114/-/DCSupplemental.

Attached Files

Published - PNAS-2017-Gu-E2166-75.pdf

Submitted - 049312.full.pdf

Supplemental Material - pnas.1613916114.sm01.avi

Supplemental Material - pnas.1613916114.sm02.avi

Supplemental Material - pnas.1613916114.sm03.avi

Supplemental Material - pnas.1613916114.sm04.avi

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Supplemental Material - pnas.1613916114.sm08.avi

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Additional details

Created:
August 22, 2023
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