Phosphorylation of NUMA occurs during nuclear breakdown and not mitotic spindle assembly

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dc.contributor.authorSparks, Cynthia A.
dc.contributor.authorFey, Edward G.
dc.contributor.authorVidair, Charles A.
dc.contributor.authorDoxsey, Stephen J.
dc.contributor.departmentProgram in Molecular Medicine
dc.contributor.departmentDepartment of Cell Biology
dc.contributor.departmentMorningside Graduate School of Biomedical Sciences
dc.date2022-08-11T08:08:48.000
dc.date.accessioned2022-08-23T16:08:59Z
dc.date.available2022-08-23T16:08:59Z
dc.date.issued1995-11-01
dc.date.submitted2009-01-12
dc.description.abstractNuMA, the nuclear mitotic apparatus protein, is a component of the nuclear matrix at interphase that redistributes to the spindle poles at mitosis. While the function of NuMA is not known, it has been implicated in spindle organization during mitosis and nuclear reformation. Phosphorylation is thought to play a regulatory role in NuMA function. In this study, NuMA phosphorylation was examined through the cell cycle using highly synchronized cells. In intact cells labeled with 32P-orthophosphate, NuMA appeared as a 250 kDa phosphoprotein in interphase that shifted to a higher apparent molecular mass in mitosis. The shift was due to phosphorylation as shown by reduction of the shifted band to interphase mobility by phosphatase treatment. This phosphorylation event occurred roughly at the G2/M transition at the time of NuMA's release from the nucleus and its redistribution to the mitotic spindle. However, mitotic phosphorylation did not require spindle formation since the phosphorylated species was detected in nocodazole-treated cells lacking microtubule spindles. Dephosphorylation of NuMA occurred in two distinct steps, after lamin B assembled into the nuclear lamina, in early G1 and at the end of G1. Based on the timing of the phosphorylation and dephosphorylation observed in this study, we propose that they may play a role in nuclear events such as nuclear organization, transcription, or initiation of DNA replication at G1/S.
dc.identifier.citation<p>J Cell Sci. 1995 Nov;108 ( Pt 11):3389-96.</p>
dc.identifier.contextkey692139
dc.identifier.issn0021-9533 (Print)
dc.identifier.legacycoverpagehttps://escholarship.umassmed.edu/gsbs_sp/1145
dc.identifier.pmid8586651
dc.identifier.submissionpathgsbs_sp/1145
dc.identifier.urihttps://hdl.handle.net/20.500.14038/32583
dc.language.isoen_US
dc.relation<p><a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&list_uids=8586651&dopt=Abstract">Link to Article in PubMed</a></p>
dc.relation.urlhttp://jcs.biologists.org/cgi/content/abstract/108/11/3389
dc.source.journaltitleJournal of cell science
dc.source.pages3389-96
dc.source.volume108 ( Pt 11)
dc.titlePhosphorylation of NUMA occurs during nuclear breakdown and not mitotic spindle assembly
dc.typeJournal Article
dspace.entity.typePublication
html.description.abstract<p>NuMA, the nuclear mitotic apparatus protein, is a component of the nuclear matrix at interphase that redistributes to the spindle poles at mitosis. While the function of NuMA is not known, it has been implicated in spindle organization during mitosis and nuclear reformation. Phosphorylation is thought to play a regulatory role in NuMA function. In this study, NuMA phosphorylation was examined through the cell cycle using highly synchronized cells. In intact cells labeled with 32P-orthophosphate, NuMA appeared as a 250 kDa phosphoprotein in interphase that shifted to a higher apparent molecular mass in mitosis. The shift was due to phosphorylation as shown by reduction of the shifted band to interphase mobility by phosphatase treatment. This phosphorylation event occurred roughly at the G2/M transition at the time of NuMA's release from the nucleus and its redistribution to the mitotic spindle. However, mitotic phosphorylation did not require spindle formation since the phosphorylated species was detected in nocodazole-treated cells lacking microtubule spindles. Dephosphorylation of NuMA occurred in two distinct steps, after lamin B assembled into the nuclear lamina, in early G1 and at the end of G1. Based on the timing of the phosphorylation and dephosphorylation observed in this study, we propose that they may play a role in nuclear events such as nuclear organization, transcription, or initiation of DNA replication at G1/S.</p>
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