Human ASPM participates in spindle organisation, spindle orientation and cytokinesis

BMC Cell Biology

Research Article

Jonathan M Askham¹  C Geoffrey Woods²  Anna-Maria Bergh³  David M Glover³  Carol Midgley⁴  Sandra M Bell⁵  Emma Roberts⁵  Jacquelyn Bond⁵  Ruth K Binns⁵  Ewan E Morrison⁵  Julie Higgins⁵  Christopher Bennett⁶  Saghira M Sharif⁶ 

[1] CRUK Clinical Centre at Leeds, Division of Cancer Medicine Research, Leeds Institute of Molecular Medicine, St James's University Hospital, LS9 7TF, Leeds, UK;Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Addenbrooke's Hospital, Hills Road, CB2 2XY, Cambridge, UK;Cancer Research UK Cell Cycle Genetics Research Group, University of Cambridge, Department of Genetics, Downing Street, CB2 3EH, Cambridge, UK;Department of Life Sciences, The Open University, MK7 6AA, Walton Hall, Milton Keynes, UK;Section of Ophthalmology and Neuroscience, Wellcome Trust Brenner Building, Leeds Institute of Molecular Medicine, University of Leeds, St. James's University Hospital, LS9 7TF, Leeds, UK;Yorkshire Regional Genetics Service, Yorkshire Regional Genetics Service, Ashley Wing, St James's University Hospital, LS9 7TF, Leeds, UK;

关键词: Mitotic Spindle;    Neural Progenitor Cell;    Spindle Pole;    U2OS Cell;    Cleavage Furrow;   

DOI  :  10.1186/1471-2121-11-85

 received in 2010-02-10, accepted in 2010-11-02,  发布年份 2010

来源: Springer

【 摘 要 】

BackgroundMutations in the A bnormal Sp indle M icrocephaly related gene (ASPM) 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).ResultsWe 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. ASPM 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 ASPM 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 C-terminal fragments cause severe spindle assembly defects and cytokinesis failure in cultured cells.ConclusionsThese observations indicate that ASPM participates in spindle organisation, spindle positioning and cytokinesis in all dividing cells and that the extreme C-terminus of the protein is required for ASPM localisation and function. Our data supports the hypothesis that the MCPH phenotype caused by ASPM mutation is a consequence of mitotic aberrations during neurogenesis. We propose the effects of ASPM 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.

【 授权许可】

Unknown   
© Higgins et al; licensee BioMed Central Ltd. 2010. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.