Biology subjects

Toya, M.

Publications and source records attributed to Toya, M..

4 recordsLinked to original sources

bioRxiv2025

Camsap3-Mediated Microtubules Maintain Transzonal Projections Essential for Germline-Soma Communication during Ovarian Follicle Maturation in Mice

Oocytes are surrounded and nursed by layers of maternal somatic granulosa cells (GCs) in ovarian follicles. Within a follicle, GCs extend actin-containing transzonal projections (TZPs) to an oocyte across the zona pellucida to establish communication. In contrast, microtubules have rarely been observed in some TZPs, and their significance in TZP organisation and functions for follicular maturation remain largely unknown. Here, using super-resolution microscopy, we visualised the presence of microtubules alongside F-actin in most TZPs. Knockout (KO) mice of the microtubule minus-end binding protein Camsap3 (calmodulin-regulated spectrin-associated protein 3) exhibited infertility with fewer developing late-stage follicles. In earlier stages of Camsap3-KO follicles, the number of TZPs was reduced compared to that in wild-type follicles, and microtubules in TZPs were disorganised, which led to a decrease in physical contact between GCs and oocytes. We also found that TZP morphology in wild-type follicles transforms over time during follicle development, and Camsap3 modulates TZP morphology by assisting the organisation of microtubules as well as F-actin. Our findings thus suggest that Camsap3-mediated microtubules play a crucial role in governing the number and morphology of TZPs to ensure successful follicle development for the production of fertile oocytes.

cell biology↗

bioRxiv2022

Germline-specific role for unconventional components of the γ-tubulin complex in Caenorhabditis elegans

The {gamma}-tubulin complex ({gamma}TuC) is a widely conserved microtubule nucleator, but some of its components GCP4-6. Here, we identified two {gamma}TuC-associated proteins in C. elegans, namely GTAP-1 and -2, for which apparent orthologs were detected only in the genus Caenorhabditis. Their centrosomal localization was interdependent. In early C. elegans embryos, whereas the conserved {gamma}TuC component MZT-1/MOZART1 was essential for the localization of centrosomal {gamma}-tubulin, depletion of GTAP-1 and/or -2 caused up to 50% reduction of centrosomal {gamma}-tubulin and precocious disassembly of spindle poles during mitotic telophase. In the adult germline, GTAP-1 and GTP-2 contributed to the efficient recruitment of {gamma}TuC to the plasma membrane. Depletion of GTAP-1, but not GTAP-2, severely disrupted both the microtubule array and the honeycomb-like structure in the adult germline. We propose that GTAP-1 and -2 are unconventional components of {gamma}TuC that contribute to the organization of both centrosomal and non-centrosomal microtubules by targeting the {gamma}TuC to specific subcellular sites in a tissue-specific manner. SUMMARY STATEMENTHaruta et al. show that GTAP-1 and -2, two unconventional components of the {gamma}-tubulin complex ({gamma}TuC) in C. elegans, contribute to targeting the {gamma}TuC to embryonic centrosomes and germ-cell membrane in adults.

cell biology↗

bioRxiv2022

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 attached chromosomes. Although TOG/XMAP215 orthologs are generally accepted as microtubule polymerases, Dis1 promoted microtubule catastrophe in vitro and in vivo. Notably, microtubule catastrophe was promoted when the tip was attached to kinetochores, as they steadily anchored Dis1 at the kinetochore-microtubule interface. Engineered Dis1 oligomers artificially tethered at a chromosome arm region induced the shortening of microtubules in contact, frequently pulling the chromosome arm towards the vicinity of spindle poles in meiocytes. Thus, unlike Alp14 and other TOG/XMAP215 orthologs, Dis1 plays an unconventional role in promoting microtubule catastrophe, thereby driving chromosome movement.

cell biology↗

bioRxiv2021

Tracheal motile cilia require CAMSAP3 for formation of central microtubule pair and coordinated beating

Motile cilia of multiciliated epithelial cells undergo synchronized beating to produce fluid flow along the luminal surface of various organs. Each motile cilium consists of an axoneme and a basal body, which are linked by a transition zone. The axoneme exhibits a characteristic 9+2 microtubule arrangement important for ciliary motion, but how this microtubule system is generated is not yet fully understood. Here we show that CAMSAP3, a protein that can stabilize the minus end of a microtubule, concentrates at multiple sites of the cilium-basal body complex, including the upper region of the transition zone or the axonemal basal plate where the central pair of microtubules (CP) initiates. CAMSAP3 dysfunction resulted in loss of the CP and partial distortion of the basal plate, as well as the failure of multicilia to undergo synchronized beating. These findings suggest that CAMSAP3 plays pivotal roles in the formation or stabilization of the CP by localizing at the basal region of the axoneme, and thereby supports the coordinated motion of multicilia in airway epithelial cells.

cell biology↗