The nucleus serves as the pacemaker for the cell cycle
- Department of Chemical and Systems Biology, Stanford Medicine, United States
- Department of Molecular and Cellular Physiology, Stanford Medicine, United States
- Department of Biology, Stanford University, United States
- Department of Genetics, Stanford Medicine, United States
- Department of Biochemistry, Stanford Medicine, United States
Figures
Figure 1 with 3 supplements
Cycling Xenopus egg extract resolved in two dimensions.
(A) Experimental scheme. (B–E) Analysis of a typical cycling extract. (B) Comparison of NLS-mCherry (green) and SiR-tubulin (red) fluorescence through two cycles. Fluorescence was measured in a …
Figure 1—figure supplement 1
Heat maps showing the dynamics of mitosis for the experiment shown in Figure 1.
The fluorescence images are identical to the interphase snapshots shown in Figure 1C and are included for comparison. The dark regions in the heat maps are the areas where mitosis occurred earliest.
Figure 1—video 1
Trigger waves of tubulin depolymerization and polymerization in Xenopus extract supplemented with sperm.
Related to Figure 1.
Figure 1—video 2
Close up view of a dividing nuclear trigger wave source.
Related to Figure 1 and Figure 1—video 1.
Figure 2 with 3 supplements
Demembranated sperm promotes mitotic initiation by shortening the cycle time.
(A) Typical sperm-mediated mitotic trigger waves. Nuclei (NLS-mCherry) are shown in green and microtubules (SiR-tubulin) in red. The advancing fronts of mitosis are depicted in blue and the …
Figure 2—figure supplement 1
Mitosis initiating from a source at the edge of a well.
In this cycle, the first place at which mitosis occurred was a point on the edge of the well with no obvious nucleus nearby. Ten minutes later, mitosis began initiating at several nuclei at once.
Figure 2—video 1
Three classes of mitotic sources: others (left), nucleus-associated (center), and edge-associated (right).
Figure 2—video 2
Trigger waves of tubulin depolymerization and polymerization in a second Xenopus extract supplemented with sperm.
Related to Figure 2.
Figure 3 with 1 supplement
Mitotic waves in cycling extracts with no added sperm chromatin, DNA, or centrosomes.
(A) Montage from a typical experiment showing the microtubules (top) and the heat map representation of the mitotic dynamics (bottom) for the first five cycles. Edge-associated sources are shown in …
Figure 3—video 1
Trigger waves of tubulin depolymerization and polymerization in a Xenopus extract supplemented with no sperm, centrosomes, or nuclei added.
Related to Figure 3.
Figure 4 with 3 supplements
Centrosomes promote cytoplasmic organization and division of the cell-like compartments, but are not strong pacemaker sources.
(A) Identification of centrosomes in an extract supplemented with purified HeLa cell centrosomes. (B) Montage showing that centrosomes duplicate and promote the division of cell-like compartments. …
Figure 4—figure supplement 1
Montage of an extract with added boiled centrosomes (A) or normal centrosomes (B).
Note there appears to be one functional centrosome in interphase 1 in (A), which subsequently replicates and divides, versus numerous functional centrosomes in (B).
Figure 4—video 1
Trigger waves of tubulin depolymerization and polymerization in a Xenopus extract supplemented with purified HeLa cell centrosomes.
Related to Figure 4.
Figure 4—video 2
Trigger waves of tubulin depolymerization and polymerization in a Xenopus extract supplemented with purified HeLa cell centrosomes and aphidicolin (15 µM).
Related to Figure 4.
Figure 5 with 2 supplements
Phage DNA forms nuclei that can act as trigger wave sources.
(A) Montage from a typical experiment showing the microtubules (top) and the heat map representation of the microtubule sources (bottom) for cycles 2, 4, 6, 8, and 10. Nucleus-associated sources are …
Figure 5—video 1
Trigger waves of tubulin depolymerization and polymerization in a Xenopus extract supplemented with λ-bacteriophage DNA (5 µg/ml).
Related to Figure 5.
Figure 5—video 2
Trigger waves of tubulin depolymerization and polymerization in a Xenopus extract supplemented with purified HeLa cell centrosomes and λ-bacteriophage DNA (5 µg/ml).
Related to Figure 5.
Tables
Key resources table
| Reagent type (species) or resource | Designation | Source or reference | Identifiers | Additional information |
|---|---|---|---|---|
| Strain, strain background | Xenopus laevis | NASCO | LM00535MX | female |
| Cell line | HeLa centrin-GFP | Tsou and Stearns, 2006 | ||
| Peptide, recombinant protein | GST-NLS-mCherry | Chang and Ferrell, 2013 | ||
| Chemical compound, drug | SiR-tubulin | Spirochrome | CY-SC002 | |
| Chemical compound, drug | aphidicolin | Calbiochem | CAS 38966-21-1 | |
| Chemical compound, drug | λ-DNA | New England Biolabs | N3011S | |
| Software, algorithm | custom-made Matlab scripts | available at https://purl.stanford.edu/fm814ch0699 | ||
| Other | demembranated sperm | Murray, 1991 |
