Cargando…

Nuclear Isoforms of Neurofibromin Are Required for Proper Spindle Organization and Chromosome Segregation

Mitotic spindles are highly organized, microtubule (MT)-based, transient structures that serve the fundamental function of unerring chromosome segregation during cell division and thus of genomic stability during tissue morphogenesis and homeostasis. Hence, a multitude of MT-associated proteins (MAP...

Descripción completa

Detalles Bibliográficos
Autores principales: Peta, Charoula, Tsirimonaki, Emmanouella, Samouil, Dimitris, Georgiadou, Kyriaki, Mangoura, Dimitra
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7690890/
https://www.ncbi.nlm.nih.gov/pubmed/33114250
http://dx.doi.org/10.3390/cells9112348
_version_ 1783614172039217152
author Peta, Charoula
Tsirimonaki, Emmanouella
Samouil, Dimitris
Georgiadou, Kyriaki
Mangoura, Dimitra
author_facet Peta, Charoula
Tsirimonaki, Emmanouella
Samouil, Dimitris
Georgiadou, Kyriaki
Mangoura, Dimitra
author_sort Peta, Charoula
collection PubMed
description Mitotic spindles are highly organized, microtubule (MT)-based, transient structures that serve the fundamental function of unerring chromosome segregation during cell division and thus of genomic stability during tissue morphogenesis and homeostasis. Hence, a multitude of MT-associated proteins (MAPs) regulates the dynamic assembly of MTs in preparation for mitosis. Some tumor suppressors, normally functioning to prevent tumor development, have now emerged as significant MAPs. Among those, neurofibromin, the product of the Neurofibromatosis-1 gene (NF1), a major Ras GTPase activating protein (RasGAP) in neural cells, controls also the critical function of chromosome congression in astrocytic cellular contexts. Cell type- and development-regulated splicings may lead to the inclusion or exclusion of NF1exon51, which bears a nuclear localization sequence (NLS) for nuclear import at G2; yet the functions of the produced NLS and ΔNLS neurofibromin isoforms have not been previously addressed. By using a lentiviral shRNA system, we have generated glioblastoma SF268 cell lines with conditional knockdown of NLS or ΔNLS transcripts. In dissecting the roles of NLS or ΔNLS neurofibromins, we found that NLS-neurofibromin knockdown led to increased density of cytosolic MTs but loss of MT intersections, anastral spindles featuring large hollows and abnormal chromosome positioning, and finally abnormal chromosome segregation and increased micronuclei frequency. Therefore, we propose that NLS neurofibromin isoforms exert prominent mitotic functions.
format Online
Article
Text
id pubmed-7690890
institution National Center for Biotechnology Information
language English
publishDate 2020
publisher MDPI
record_format MEDLINE/PubMed
spelling pubmed-76908902020-11-27 Nuclear Isoforms of Neurofibromin Are Required for Proper Spindle Organization and Chromosome Segregation Peta, Charoula Tsirimonaki, Emmanouella Samouil, Dimitris Georgiadou, Kyriaki Mangoura, Dimitra Cells Article Mitotic spindles are highly organized, microtubule (MT)-based, transient structures that serve the fundamental function of unerring chromosome segregation during cell division and thus of genomic stability during tissue morphogenesis and homeostasis. Hence, a multitude of MT-associated proteins (MAPs) regulates the dynamic assembly of MTs in preparation for mitosis. Some tumor suppressors, normally functioning to prevent tumor development, have now emerged as significant MAPs. Among those, neurofibromin, the product of the Neurofibromatosis-1 gene (NF1), a major Ras GTPase activating protein (RasGAP) in neural cells, controls also the critical function of chromosome congression in astrocytic cellular contexts. Cell type- and development-regulated splicings may lead to the inclusion or exclusion of NF1exon51, which bears a nuclear localization sequence (NLS) for nuclear import at G2; yet the functions of the produced NLS and ΔNLS neurofibromin isoforms have not been previously addressed. By using a lentiviral shRNA system, we have generated glioblastoma SF268 cell lines with conditional knockdown of NLS or ΔNLS transcripts. In dissecting the roles of NLS or ΔNLS neurofibromins, we found that NLS-neurofibromin knockdown led to increased density of cytosolic MTs but loss of MT intersections, anastral spindles featuring large hollows and abnormal chromosome positioning, and finally abnormal chromosome segregation and increased micronuclei frequency. Therefore, we propose that NLS neurofibromin isoforms exert prominent mitotic functions. MDPI 2020-10-23 /pmc/articles/PMC7690890/ /pubmed/33114250 http://dx.doi.org/10.3390/cells9112348 Text en © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Peta, Charoula
Tsirimonaki, Emmanouella
Samouil, Dimitris
Georgiadou, Kyriaki
Mangoura, Dimitra
Nuclear Isoforms of Neurofibromin Are Required for Proper Spindle Organization and Chromosome Segregation
title Nuclear Isoforms of Neurofibromin Are Required for Proper Spindle Organization and Chromosome Segregation
title_full Nuclear Isoforms of Neurofibromin Are Required for Proper Spindle Organization and Chromosome Segregation
title_fullStr Nuclear Isoforms of Neurofibromin Are Required for Proper Spindle Organization and Chromosome Segregation
title_full_unstemmed Nuclear Isoforms of Neurofibromin Are Required for Proper Spindle Organization and Chromosome Segregation
title_short Nuclear Isoforms of Neurofibromin Are Required for Proper Spindle Organization and Chromosome Segregation
title_sort nuclear isoforms of neurofibromin are required for proper spindle organization and chromosome segregation
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7690890/
https://www.ncbi.nlm.nih.gov/pubmed/33114250
http://dx.doi.org/10.3390/cells9112348
work_keys_str_mv AT petacharoula nuclearisoformsofneurofibrominarerequiredforproperspindleorganizationandchromosomesegregation
AT tsirimonakiemmanouella nuclearisoformsofneurofibrominarerequiredforproperspindleorganizationandchromosomesegregation
AT samouildimitris nuclearisoformsofneurofibrominarerequiredforproperspindleorganizationandchromosomesegregation
AT georgiadoukyriaki nuclearisoformsofneurofibrominarerequiredforproperspindleorganizationandchromosomesegregation
AT mangouradimitra nuclearisoformsofneurofibrominarerequiredforproperspindleorganizationandchromosomesegregation