Solved 22 What is the mitotic spindle Biology Diagrams Abnormal mitotic spindle geometry: permanent vs. transient. The bipolar geometry of the mitotic spindle is essential for accurate chromosome segregation, and already a century ago Theodor Boveri postulated that supernumerary centrosomes could lead to the production of aneuploid cells [23,24].Observations of mitosis in both transformed and non-transformed cells reveal that multipolar mitotic In this article, we provide guidelines for identifying specific mitotic stages and for classifying normal and deviant mitotic phenotypes. We hope this will clarify confusion about how certain defects are classified and help investigators avoid misnomers, misclassification, and/or misinterpretation, thus leading to a unified and standardized
A major contributor to this coordination is the mitotic spindle checkpoint. As detailed in another contribution in this series, defects in mitotic spindle assembly and chromosome alignment activate the spindle checkpoint, which delays cells in M phase. Optimally this delay allows the recovery of the normal spindle and balanced chromosome
A guide to classifying mitotic stages and mitotic defects in fixed ... Biology Diagrams
Common mitotic spindle defects. Monopolar spindle induced by kinesin-5 inhibition (10 ฮผm STLC, 90 min) in hTERT RPE-1 cell (a). Prometaphase hTERT RPE-1 cell (same cell as Fig. 1b) with spindle axis oriented perpendicularly to the substrate (b). Images of the two focal planes in which the spindle poles resided are shown in the MT column. In general, lagging chromosomes could be generated by various mechanisms; for example, merotelic attachments (where a single kinetochore attaches to microtubules from opposite spindle poles) would generate lagging chromosomes involving single chromatids, 37 while defects in either sister chromatid resolution or removal of sister chromatid Correct alignment of the mitotic spindle during cell division is crucial for cell fate determination, tissue organization, and development. Mutations causing brain diseases and cancer in humans and mice have been associated with spindle orientation defects.
The spindle defects caused by OGT and OGA overexpression increased the population of aneuploid cells. 14 In order to determine if OGA knockdown cells produced defective spindles and increased aneuploidy, we stained OGA knockdown and control cells for ฮฒ-tubulin and DNA and counted the number of cells with aberrant spindles or were multinucleated . impacts mitotic spindle pole integrity. This includes release of MT minus-ends from the centrosome, leading to PCM dispersion and centriole mis-posi-tioning at the spindle poles. Mechanistically, we show that these defects result from abnormal spin-dle MT dynamics due to defective kinetochore-MT attachments. Importantly, restoring mitotic spindle
