During cytokinesis, the central spindle, a bundle of interdigitated anti-parallel microtubules between separating chromosomes, recruits various cytokinetic regulator proteins to the cleavage region. Here, we show that the level of protein ubiquitylation is strikingly and transiently elevated in Aurora B kinase-positive double-band regions of the central spindle during cytokinesis. Two deubiquit...

We investigated the mechanism of poleward microtubule flux in the mitotic spindle by generating spindle subassemblies in Xenopus egg extracts in vitro and assaying their ability to flux by photoactivation of fluorescence and low-light multichannel fluorescence video-microscopy. We find that monopolar intermediates of in vitro spindle assembly (half-spindles) exhibit normal poleward flux, as do ...

Metaphase describes a phase of mitosis where chromosomes are attached and oriented on the bipolar spindle for subsequent segregation at anaphase. In diverse cell types, the metaphase spindle is maintained at characteristic constant length [1-3]. Metaphase spindle length is proposed to be regulated by a balance of pushing and pulling forces generated by distinct sets of spindle microtubules (MTs...

Little is known about the mechanisms of mitotic spindle orientation during mammary gland morphogenesis. Here, we report the presence of huntingtin, the protein mutated in Huntington's disease, in mouse mammary basal and luminal cells throughout mammogenesis. Keratin 5-driven depletion of huntingtin results in a decreased pool and specification of basal and luminal progenitors, and altered mamma...

We have investigated the intracellular roles of an Xklp2-related kinesin motor, KRP(180), in positioning spindle poles during early sea urchin embryonic cell division using quantitative, real-time analysis. Immunolocalization reveals that KRP(180) concentrates on microtubules in the central spindle, but is absent from centrosomes. Microinjection of inhibitory antibodies and dominant negative co...

During cell division, microtubules are arranged in a large bipolar structure, the mitotic spindle, to segregate the duplicated chromosomes. Antiparallel microtubule overlaps in the spindle center are essential for establishing bipolarity and maintaining spindle stability throughout mitosis. In anaphase, this antiparallel microtubule array is tightly bundled forming the midzone, which serves as ...

Cdc34/Ubc3 is a ubiquitin-conjugating enzyme that functions in targeting proteins for proteasome-mediated degradation at the G1 to S cell cycle transition. Elevation of Cdc34 protein levels by microinjection of bacterially expressed Cdc34 into mammalian cells at prophase inhibited chromosome congression to the metaphase plate with many chromosomes remaining near the spindle poles. Chromosome co...

Combining microtubule-targeting antimitotic drugs with targeted apoptosis potentiators is a promising new chemotherapeutic strategy to treat cancer. In this study, we investigate the cellular mechanism by which navitoclax (previously called ABT-263), a Bcl-2 family inhibitor, potentiates apoptosis triggered by paclitaxel and an inhibitor of kinesin-5 (K5I, also called a KSP inhibitor), across a...

We have investigated the intracellular roles of an Xklp2-related kinesin motor, KRP 180 , in positioning spindle poles during early sea urchin embryonic cell division using quantitative, real-time analysis. Immunolocalization reveals that KRP 180 concentrates on microtubules in the central spindle, but is absent from centrosomes. Microinjection of inhibitory antibodies and dominant negative con...

The molecular motor protein kinesin plays a key role in fundamental cellular processes such as intracellular transport, mitotic spindle formation, and cytokinesis, with important implications for neurodegenerative and cancer disease pathways. Recently, kinesin has been studied as a paradigm for the tailored design of nano-bio sensor and other nanoscale systems. As it processes along a microtubu...