Subtopic Deep Dive
Mitotic Spindle Assembly and Bipolarity
Research Guide
What is Mitotic Spindle Assembly and Bipolarity?
Mitotic spindle assembly and bipolarity refers to the microtubule-based structure formation ensuring bipolar orientation for accurate chromosome segregation during mitosis.
Microtubules organize into bipolar spindles via motor proteins like Eg5 and crosslinking factors. Small molecule inhibitors such as monastrol and hesperadin disrupt bipolarity, revealing key mechanisms (Kapoor et al., 2000; Hauf et al., 2003). Over 10,000 citations across provided papers highlight its centrality in mitosis research.
Why It Matters
Defects in spindle bipolarity cause multipolar spindles and aneuploidy, driving cancer progression (Ganem et al., 2009). Taxol stabilizes microtubules to block mitosis at low nanomolar concentrations, forming the basis for chemotherapy (Jordan et al., 1993). Inhibitors like monastrol target Eg5 kinesin to probe assembly, aiding drug discovery for chromosomal instability diseases (Kapoor et al., 2000; Mayer et al., 1999).
Key Research Challenges
Achieving Bipolar Spindle Formation
Centrosome amplification leads to multipolar spindles and chromosomal instability without p53 (Fukasawa et al., 1996). Extra centrosomes cluster improperly, causing aneuploidy (Ganem et al., 2009). Motor proteins like Eg5 must balance forces for bipolarity (Kapoor et al., 2000).
Correcting Kinetochore Attachments
Aurora B kinase corrects erroneous microtubule-kinetochore attachments via hesperadin inhibition (Hauf et al., 2003). This maintains the spindle assembly checkpoint. Errors persist without proper destabilization signals.
Regulating Mitotic Checkpoints
Cyclin-dependent kinases control entry into mitosis, with disruptions causing spindle defects (Malumbres, 2014). Taxol induces metaphase arrest by stabilizing microtubules (Jordan et al., 1993). Checkpoint genes like RAD9 ensure DNA repair before anaphase.
Essential Papers
Small Molecule Inhibitor of Mitotic Spindle Bipolarity Identified in a Phenotype-Based Screen
Thomas U. Mayer, Tarun M. Kapoor, Stephen J. Haggarty et al. · 1999 · Science · 1.7K citations
Small molecules that perturb specific protein functions are valuable tools for dissecting complex processes in mammalian cells. A combination of two phenotype-based screens, one based on a specific...
Cyclin-dependent kinases
Marcos Malumbres · 2014 · Genome biology · 1.6K citations
A mechanism linking extra centrosomes to chromosomal instability
Neil J. Ganem, Susana A. Godinho, David Pellman · 2009 · Nature · 1.4K citations
The small molecule Hesperadin reveals a role for Aurora B in correcting kinetochore–microtubule attachment and in maintaining the spindle assembly checkpoint
Silke Hauf, Richard W. Cole, Sabrina LaTerra et al. · 2003 · The Journal of Cell Biology · 1.2K citations
The proper segregation of sister chromatids in mitosis depends on bipolar attachment of all chromosomes to the mitotic spindle. We have identified the small molecule Hesperadin as an inhibitor of c...
Mechanism of mitotic block and inhibition of cell proliferation by taxol at low concentrations.
Mary Ann Jordan, Robert Toso, Douglas Thrower et al. · 1993 · Proceedings of the National Academy of Sciences · 1.1K citations
Taxol inhibited HeLa cell proliferation by inducing a sustained mitotic block at the metaphase/anaphase boundary. Half-maximal inhibition of cell proliferation occurred at 8 nM taxol, and mitosis w...
Abnormal Centrosome Amplification in the Absence of p53
Kenji Fukasawa, Taesaeng Choi, Ryoko Kuriyama et al. · 1996 · Science · 790 citations
The centrosome plays a vital role in mitotic fidelity, ensuring establishment of bipolar spindles and balanced chromosome segregation. Centrosome duplication occurs only once during the cell cycle ...
Disruption of Cancer Cell Replication by Alternating Electric Fields
Eilon D. Kirson, Zoya Gurvich, Rosa S. Schneiderman et al. · 2004 · Cancer Research · 783 citations
Abstract Low-intensity, intermediate-frequency (100–300 kHz), alternating electric fields, delivered by means of insulated electrodes, were found to have a profound inhibitory effect on the growth ...
Reading Guide
Foundational Papers
Start with Mayer et al. (1999) for phenotype screens identifying bipolarity inhibitors; Kapoor et al. (2000) for Eg5-monastrol mechanisms; Hauf et al. (2003) for Aurora B correction pathways.
Recent Advances
Malumbres (2014) reviews CDKs in spindle regulation; Ganem et al. (2009) links extra centrosomes to instability.
Core Methods
Small molecule screens (Mayer et al., 1999); kinesin inhibition (Kapoor et al., 2000); microtubule stabilization (Jordan et al., 1993); kinase inhibition (Hauf et al., 2003).
How PapersFlow Helps You Research Mitotic Spindle Assembly and Bipolarity
Discover & Search
Research Agent uses searchPapers and citationGraph on 'mitotic spindle bipolarity' to map 10 high-citation papers like Mayer et al. (1999, 1714 citations), then findSimilarPapers uncovers Eg5 inhibitors (Kapoor et al., 2000). exaSearch reveals phenotype-based screens linking monopolar spindles to motor proteins.
Analyze & Verify
Analysis Agent applies readPaperContent to extract monastrol's Eg5 inhibition mechanism from Kapoor et al. (2000), verifies bipolarity claims with verifyResponse (CoVe), and runs PythonAnalysis on taxol dose-response data from Jordan et al. (1993) for IC50 curve fitting with GRADE scoring statistical significance.
Synthesize & Write
Synthesis Agent detects gaps in Aurora B correction pathways post-Hauf et al. (2003), flags contradictions in centrosome clustering (Ganem et al., 2009). Writing Agent uses latexEditText, latexSyncCitations for 10 papers, latexCompile spindle diagrams via exportMermaid for bipolarity models.
Use Cases
"Analyze taxol's effect on spindle bipolarity from Jordan 1993 with dose-response stats"
Research Agent → searchPapers('taxol mitotic block') → Analysis Agent → readPaperContent + runPythonAnalysis (pandas curve_fit on 8nM IC50 data) → matplotlib plot of metaphase arrest kinetics.
"Draft review on Eg5 inhibitors with citations and spindle diagram"
Research Agent → citationGraph('Kapoor 2000 monastrol') → Synthesis Agent → gap detection → Writing Agent → latexEditText + latexSyncCitations (Mayer 1999, Kapoor 2000) + exportMermaid (bipolar spindle flowchart) → latexCompile PDF.
"Find code for simulating mitotic spindle assembly models"
Research Agent → paperExtractUrls('spindle bipolarity microtubule') → Code Discovery → paperFindGithubRepo → githubRepoInspect → runPythonAnalysis (NumPy microtubule polymerization sim) → exportCsv dynamics data.
Automated Workflows
Deep Research workflow scans 50+ papers via searchPapers on 'spindle bipolarity inhibitors', structures report with GRADE-verified claims from Mayer et al. (1999) and Hauf et al. (2003). DeepScan applies 7-step CoVe to validate monopolar spindle mechanisms in Kapoor et al. (2000), flagging citation inconsistencies. Theorizer generates hypotheses on Eg5-Aurora B interplay from citationGraph clusters.
Frequently Asked Questions
What defines mitotic spindle bipolarity?
Bipolarity is the antiparallel microtubule array with poles at opposite ends, ensured by Eg5 kinesin crosslinking (Kapoor et al., 2000). Inhibitors like monastrol induce monopolar spindles.
What are key methods for studying spindle assembly?
Phenotype-based screens identify bipolarity inhibitors (Mayer et al., 1999). Small molecules like hesperadin target Aurora B for attachment correction (Hauf et al., 2003). Taxol stabilizes microtubules to block mitosis (Jordan et al., 1993).
What are foundational papers?
Mayer et al. (1999, 1714 citations) identified spindle inhibitors via screens. Kapoor et al. (2000, 723 citations) probed Eg5 with monastrol. Hauf et al. (2003, 1151 citations) revealed Aurora B's role.
What are open problems in spindle bipolarity?
Clustering extra centrosomes without multipolarity (Ganem et al., 2009). p53-independent centrosome amplification mechanisms (Fukasawa et al., 1996). Integrating CDK regulation with motor dynamics (Malumbres, 2014).
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