Human ASPM participates in spindle organisation, spindle orientation and cytokinesis
<p>Abstract</p> <p>Background</p> <p>Mutations in the Abnormal Spindle Microcephaly related gene (<it>ASPM) </it>are the commonest cause of autosomal recessive primary microcephaly (MCPH) a disorder characterised by a small brain and associated mental retard...
| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
BMC
2010-11-01
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| Series: | BMC Cell Biology |
| Online Access: | http://www.biomedcentral.com/1471-2121/11/85 |
| _version_ | 1818776861726998528 |
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| author | Woods C Geoffrey Glover David M Bennett Christopher Sharif Saghira M Binns Ruth K Roberts Emma Askham Jonathan M Bell Sandra M Bergh Anna-Maria Midgley Carol Higgins Julie Morrison Ewan E Bond Jacquelyn |
| author_facet | Woods C Geoffrey Glover David M Bennett Christopher Sharif Saghira M Binns Ruth K Roberts Emma Askham Jonathan M Bell Sandra M Bergh Anna-Maria Midgley Carol Higgins Julie Morrison Ewan E Bond Jacquelyn |
| author_sort | Woods C Geoffrey |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>Mutations in the Abnormal Spindle Microcephaly related gene (<it>ASPM) </it>are the commonest cause of autosomal recessive primary microcephaly (MCPH) a disorder characterised by a small brain and associated mental retardation. ASPM encodes a mitotic spindle pole associated protein. It is suggested that the MCPH phenotype arises from proliferation defects in neural progenitor cells (NPC).</p> <p>Results</p> <p>We show that ASPM is a microtubule minus end-associated protein that is recruited in a microtubule-dependent manner to the pericentriolar matrix (PCM) at the spindle poles during mitosis. <it>ASPM </it>siRNA reduces ASPM protein at the spindle poles in cultured U2OS cells and severely perturbs a number of aspects of mitosis, including the orientation of the mitotic spindle, the main determinant of developmental asymmetrical cell division. The majority of ASPM depleted mitotic cells fail to complete cytokinesis. In MCPH patient fibroblasts we show that a pathogenic <it>ASPM </it>splice site mutation results in the expression of a novel variant protein lacking a tripeptide motif, a minimal alteration that correlates with a dramatic decrease in ASPM spindle pole localisation. Moreover, expression of dominant-negative ASPM <it>C</it>-terminal fragments cause severe spindle assembly defects and cytokinesis failure in cultured cells.</p> <p>Conclusions</p> <p>These observations indicate that ASPM participates in spindle organisation, spindle positioning and cytokinesis in all dividing cells and that the extreme <it>C</it>-terminus of the protein is required for ASPM localisation and function. Our data supports the hypothesis that the MCPH phenotype caused by <it>ASPM </it>mutation is a consequence of mitotic aberrations during neurogenesis. We propose the effects of <it>ASPM </it>mutation are tolerated in somatic cells but have profound consequences for the symmetrical division of NPCs, due to the unusual morphology of these cells. This antagonises the early expansion of the progenitor pool that underpins cortical neurogenesis, causing the MCPH phenotype.</p> |
| first_indexed | 2024-12-18T11:19:40Z |
| format | Article |
| id | doaj.art-2bff4252d30c4caaac49be6517507919 |
| institution | Directory Open Access Journal |
| issn | 1471-2121 |
| language | English |
| last_indexed | 2024-12-18T11:19:40Z |
| publishDate | 2010-11-01 |
| publisher | BMC |
| record_format | Article |
| series | BMC Cell Biology |
| spelling | doaj.art-2bff4252d30c4caaac49be65175079192022-12-21T21:09:50ZengBMCBMC Cell Biology1471-21212010-11-011118510.1186/1471-2121-11-85Human ASPM participates in spindle organisation, spindle orientation and cytokinesisWoods C GeoffreyGlover David MBennett ChristopherSharif Saghira MBinns Ruth KRoberts EmmaAskham Jonathan MBell Sandra MBergh Anna-MariaMidgley CarolHiggins JulieMorrison Ewan EBond Jacquelyn<p>Abstract</p> <p>Background</p> <p>Mutations in the Abnormal Spindle Microcephaly related gene (<it>ASPM) </it>are the commonest cause of autosomal recessive primary microcephaly (MCPH) a disorder characterised by a small brain and associated mental retardation. ASPM encodes a mitotic spindle pole associated protein. It is suggested that the MCPH phenotype arises from proliferation defects in neural progenitor cells (NPC).</p> <p>Results</p> <p>We show that ASPM is a microtubule minus end-associated protein that is recruited in a microtubule-dependent manner to the pericentriolar matrix (PCM) at the spindle poles during mitosis. <it>ASPM </it>siRNA reduces ASPM protein at the spindle poles in cultured U2OS cells and severely perturbs a number of aspects of mitosis, including the orientation of the mitotic spindle, the main determinant of developmental asymmetrical cell division. The majority of ASPM depleted mitotic cells fail to complete cytokinesis. In MCPH patient fibroblasts we show that a pathogenic <it>ASPM </it>splice site mutation results in the expression of a novel variant protein lacking a tripeptide motif, a minimal alteration that correlates with a dramatic decrease in ASPM spindle pole localisation. Moreover, expression of dominant-negative ASPM <it>C</it>-terminal fragments cause severe spindle assembly defects and cytokinesis failure in cultured cells.</p> <p>Conclusions</p> <p>These observations indicate that ASPM participates in spindle organisation, spindle positioning and cytokinesis in all dividing cells and that the extreme <it>C</it>-terminus of the protein is required for ASPM localisation and function. Our data supports the hypothesis that the MCPH phenotype caused by <it>ASPM </it>mutation is a consequence of mitotic aberrations during neurogenesis. We propose the effects of <it>ASPM </it>mutation are tolerated in somatic cells but have profound consequences for the symmetrical division of NPCs, due to the unusual morphology of these cells. This antagonises the early expansion of the progenitor pool that underpins cortical neurogenesis, causing the MCPH phenotype.</p>http://www.biomedcentral.com/1471-2121/11/85 |
| spellingShingle | Woods C Geoffrey Glover David M Bennett Christopher Sharif Saghira M Binns Ruth K Roberts Emma Askham Jonathan M Bell Sandra M Bergh Anna-Maria Midgley Carol Higgins Julie Morrison Ewan E Bond Jacquelyn Human ASPM participates in spindle organisation, spindle orientation and cytokinesis BMC Cell Biology |
| title | Human ASPM participates in spindle organisation, spindle orientation and cytokinesis |
| title_full | Human ASPM participates in spindle organisation, spindle orientation and cytokinesis |
| title_fullStr | Human ASPM participates in spindle organisation, spindle orientation and cytokinesis |
| title_full_unstemmed | Human ASPM participates in spindle organisation, spindle orientation and cytokinesis |
| title_short | Human ASPM participates in spindle organisation, spindle orientation and cytokinesis |
| title_sort | human aspm participates in spindle organisation spindle orientation and cytokinesis |
| url | http://www.biomedcentral.com/1471-2121/11/85 |
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