A germline-specific role for unconventional components of the γ-tubulin complex in Caenorhabditis elegans.

The γ-tubulin complex (γTuC) is a widely conserved microtubule nucleator, but some of its components, namely GCP4, GCP5 and GCP6 (also known as TUBGCP4, TUBGCP5 and TUBGCP6, respectively), have not been detected in Caenorhabditis elegans. Here, we identified two γTuC-associated proteins in C. elegans, GTAP-1 and GTAP-2, for which apparent orthologs were detected only in the genus Caenorhabditis.

Fission yeast Dis1 is an unconventional TOG/XMAP215 that induces microtubule catastrophe to drive chromosome pulling.

The shortening of microtubules attached to kinetochores is the driving force of chromosome movement during cell division. Specific kinesins are believed to shorten microtubules but are dispensable for viability in yeast, implying the existence of additional factors responsible for microtubule shortening. Here, we demonstrate that Dis1, a TOG/XMAP215 ortholog in fission yeast, promotes microtubule shortening to carry chromosomes.

Dual Impact of a Benzimidazole Resistant β-Tubulin on Microtubule Behavior in Fission Yeast.

The cytoskeleton microtubule consists of polymerized αβ-tubulin dimers and plays essential roles in many cellular events. Reagents that inhibit microtubule behaviors have been developed as antifungal, antiparasitic, and anticancer drugs. Benzimidazole compounds, including thiabendazole (TBZ), carbendazim (MBC), and nocodazole, are prevailing microtubule poisons that target β-tubulin and inhibit microtubule polymerization.

Tell the Difference Between Mitosis and Meiosis: Interplay Between Chromosomes, Cytoskeleton, and Cell Cycle Regulation.

Meiosis is a specialized style of cell division conserved in eukaryotes, particularly designed for the production of gametes. A huge number of studies to date have demonstrated how chromosomes behave and how meiotic events are controlled. Yeast substantially contributed to the understanding of the molecular mechanisms of meiosis in the past decades.

Simplification of nutritional conditions in transformation procedures for genome editing with the CRISPR/Cas9 system for fission yeast.

CRISPR/Cas9 is a powerful tool for genome editing. Several studies have been conducted to take the benefit of the versatile tool in the fission yeast Schizosaccharomyces pombe. However, the protocols for the CRISPR/Cas9 system proposed in previous studies are complicated in culture conditions compared to traditional genome editing methods.

Cyst formation in proximal renal tubules caused by dysfunction of the microtubule minus-end regulator CAMSAP3.

Epithelial cells organize an ordered array of non-centrosomal microtubules, the minus ends of which are regulated by CAMSAP3. The role of these microtubules in epithelial functions, however, is poorly understood. Here, we show that the kidneys of mice in which Camsap3 is mutated develop cysts at the proximal convoluted tubules (PCTs).

Organization of Non-centrosomal Microtubules in Epithelial Cells.

Polarized epithelial cells contain a characteristic array of microtubules in which non-centrosomal microtubules are aligned along the apical-to-basal axis of the cell with their minus ends oriented towards the apical pole. Although this unique orientation of microtubules was discovered in the late 1980s, how this orientation is established remains unresolved partly because of limited information about molecular factors that regulate the minus ends of non-centrosomal microtubules. Recent studies, however, identified novel minus end-associated proteins, revealing mechanisms by which the polarized arrays of microtubules are established in epithelial cells.

Patronin Takes a Shot at Polarity.

To specify the anterior-posterior axis of Drosophila embryos, noncentrosomal microtubules grow out from cortical regions of the oocyte and help transport axis determinants. In this issue of Developmental Cell, Nashchekin et al. (2016) report a Shot- and Patronin-dependent mechanism by which the oocyte cortex produces polarized microtubule arrays.

CAMSAP3 orients the apical-to-basal polarity of microtubule arrays in epithelial cells.

Polarized epithelial cells exhibit a characteristic array of microtubules that are oriented along the apicobasal axis of the cells. The minus-ends of these microtubules face apically, and the plus-ends face toward the basal side. The mechanisms underlying this epithelial-specific microtubule assembly remain unresolved, however.

The UBXN-2/p37/p47 adaptors of CDC-48/p97 regulate mitosis by limiting the centrosomal recruitment of Aurora A.

Coordination of cell cycle events in space and time is crucial to achieve a successful cell division. Here, we demonstrate that UBXN-2, a substrate adaptor of the AAA ATPase Cdc48/p97, is required to coordinate centrosome maturation timing with mitosis. In UBXN-2-depleted Caenorhabditis elegans embryos, centrosomes recruited more AIR-1 (Aurora A), matured precociously, and alignment of the mitotic spindle with the axis of polarity was impaired.

The nucleoporin Nup205/NPP-3 is lost near centrosomes at mitotic onset and can modulate the timing of this process in Caenorhabditis elegans embryos.

Regulation of mitosis in time and space is critical for proper cell division. We conducted an RNA interference-based modifier screen to identify novel regulators of mitosis in Caenorhabditis elegans embryos. Of particular interest, this screen revealed that the Nup205 nucleoporin NPP-3 can negatively modulate the timing of mitotic onset.

A kinase-independent role for Aurora A in the assembly of mitotic spindle microtubules in Caenorhabditis elegans embryos.

The assembly of a functional mitotic spindle is crucial for achieving successful mitosis. Aurora A kinase is one of the key regulators of mitotic events, including mitotic entry, centrosome maturation and spindle bipolarity. Caenorhabditis elegans Aurora A (AIR-1) is responsible for the assembly of γ-tubulin-independent microtubules in early embryos; however, the mechanism by which AIR-1 contributes to microtubule assembly during mitosis has been unclear.

Pob1 ensures cylindrical cell shape by coupling two distinct rho signaling events during secretory vesicle targeting.

Proper cell morphogenesis requires the co-ordination of cell polarity, cytoskeletal organization and vesicle trafficking. The Schizosaccharomyces pombe mutant pob1-664 has a curious lemon-like shape, the basis of which is not understood. Here, we found abundant vesicle accumulation in these cells, suggesting that Pob1 plays a role in vesicle trafficking.

Caenorhabditis elegans ortholog of the p24/p22 subunit, DNC-3, is essential for the formation of the dynactin complex by bridging DNC-1/p150(Glued) and DNC-2/dynamitin.

Dynactin is a multisubunit protein complex required for the activity of cytoplasmic dynein. In Caenorhabditis elegans, although 10 of the 11 dynactin subunits were identified based on the sequence similarities to their orthologs, the p24/p22 subunit has not been detected in the genome. Here, we demonstrate that DNC-3 (W10G11.

Imaging of mitotic spindle dynamics in Caenorhabditis elegans embryos.

Development of the nematode Caenorhabditis elegans is highly reproducible, and the cell division patterns are virtually invariant. Transparency of the eggshell and cells enables the observation of intracellular events with a high temporal and spatial resolution. These unique features, along with the sophisticated genetic techniques, make this organism one of the most attractive model systems for dissecting regulatory mechanisms of dynamic cellular behaviors, such as mitosis, at an organismal level.

Visualization of fluorescence-tagged proteins in fission yeast: the analysis of mitotic spindle dynamics using GFP-tubulin under the native promoter.

Mitotic spindle microtubules pull chromosomes toward each pole to generate two daughter cells. Proper spindle formation and function are required to prevent tumorigenesis and cell death. The fission yeast Schizosaccharomyces pombe has been widely used as a model organism to understand the molecular mechanism of mitosis due to its convenience in genetics, molecular biology, and cell biology.

Gamma-tubulin complex-mediated anchoring of spindle microtubules to spindle-pole bodies requires Msd1 in fission yeast.

The anchoring of microtubules to subcellular structures is critical for cell polarity and motility. Although the process of anchoring cytoplasmic microtubules to the centrosome has been studied in some detail, it is not known how spindle microtubules are anchored to the mitotic centrosome and, particularly, whether anchoring and nucleation of mitotic spindles are functionally separate. Here, we show that a fission yeast coiled-coil protein, Msd1, is required for anchoring the minus end of spindle microtubules to the centrosome equivalent, the spindle-pole body (SPB).

Mal3, the fission yeast EB1 homologue, cooperates with Bub1 spindle checkpoint to prevent monopolar attachment.

Bipolar microtubule attachment is central to genome stability. Here, we investigate the mitotic role of the fission yeast EB1 homologue Mal3. Mal3 shows dynamic inward movement along the spindle, initial emergence at the spindle pole body (SPB) and translocation towards the equatorial plane, followed by sudden disappearance.