Biology subjects

Pelisch, F.

Publications and source records attributed to Pelisch, F..

5 recordsLinked to original sources

bioRxiv2025

Outer Kinetochore Proteins form Linear Elements to Regulate Vesicle Transport

During cell division, several key regulators of chromosome segregation play additional roles during vesicle trafficking required for cytokinesis. During anaphase I in C. elegans oocytes, chromosome segregation is coordinated with vesicle trafficking to support polar body extrusion and exocytosis of extracellular matrix material. Prior to anaphase, numerous outer kinetochore proteins localize to mysterious "linear element" structures throughout the cortex in addition to chromosomes, which has been observed in oocytes of multiple species. Linear elements initially form as puncta just before nuclear envelope breakdown and rapidly assemble into larger elongated structures. As linear elements grow, they form large clusters with secretory vesicles, initiating an elaborate transport mechanism that distributes vesicles throughout the cortex by anaphase I. Linear elements dynamically interact with microtubules and endoplasmic reticulum during this process. Microtubules are required for linear element assembly, motility, and clustering with vesicles. Knockdown of a plus end microtubule binding kinetochore component also inhibits linear element growth and vesicle clustering, but not the motility of linear element puncta. Depletion of several outer kinetochore proteins causes defects in extracellular matrix formation. Therefore, linear elements facilitate the microtubule-dependent transport of vesicles for their proper distribution in the cortex. We hypothesize that outer kinetochore complexes coordinate movements of chromosomes and cytoplasmic membranes to enhance the fidelity of cell division.

cell biology↗

bioRxiv2024

CENP-C-targeted PLK-1 regulates kinetochore function in C. elegans embryos

Polo-like kinase 1 (PLK1) is present in centrosomes, nuclear envelope, and kinetochores and plays a significant role in meiosis and mitosis. PLK-1 depletion or inhibition has severe consequences for spindle assembly, spindle assembly checkpoint (SAC) activation, chromosome segregation, and cytokinesis. BUB1 targets PLK1 to the outer kinetochore and, in mammals, the inner kinetochore PLK1 targeting is mediated by the constitutive centromere associated network (CCAN). BUB1-targeted PLK1 plays a key role in SAC activation and a SAC-independent role through targeting CDC-20. In contrast, whether there is a specific, non-redundant role for inner kinetochore targeted PLK1 is unknown. Here, we used the C. elegans embryo to study the role of inner kinetochore PLK1. We found that CENP-C, the sole CCAN component in C. elegans and other species, targets PLK1 to the inner kinetochore during prometaphase and metaphase. Disruption of the CENP-C/PLK1 interaction leads to an imbalance in kinetochore components and a defect in chromosome congression, without affecting CDC-20 recruitment. These findings indicate that PLK1 kinetochore recruitment by CENP-C has at least partially distinct functions than outer kinetochore PLK1, providing a platform for better understanding the different roles played by PLK1 during mitosis.

cell biology↗

bioRxiv2022

BUB-1 and CENP-C Recruit PLK-1 to Control Chromosome Alignment and Segregation During Meiosis I in C. elegans Oocytes

Phosphorylation is a key post-translational modification that is utilised in many biological processes for the rapid and reversible regulation of protein localisation and activity. Polo-like kinase 1 (PLK-1) is essential for both mitotic and meiotic cell divisions, with key functions being conserved in eukaryotes. The roles and regulation of PLK-1 during mitosis have been well characterised. However, the discrete roles and regulation of PLK-1 during meiosis have remained obscure. Here, we used Caenorhabditis elegans (C. elegans) oocytes to show that PLK-1 plays distinct roles in meiotic spindle assembly and/or stability, chromosome alignment and segregation, and polar body extrusion during meiosis I. Furthermore, by a combination of live imaging and biochemical analysis we identified the chromosomal recruitment mechanisms of PLK-1 during C. elegans oocyte meiosis. The spindle assembly checkpoint kinase BUB-1 directly recruits PLK-1 to the kinetochore and midbivalent while the chromosome arm population of PLK-1 depends on a direct interaction with the centromeric-associated protein CENP-CHCP-4. We found that perturbing both BUB-1 and CENP-CHCP-4 recruitment of PLK-1 leads to severe meiotic defects, resulting in highly aneuploid oocytes. Overall, our results shed light on the roles played by PLK-1 during oocyte meiosis and provide a mechanistic understanding of PLK-1 targeting to meiotic chromosomes.

cell biology↗

bioRxiv2020

PP2A:B56 Regulates Meiotic Chromosome Segregation in C. elegans Oocytes

Protein Phosphatase 2A (PP2A) is an heterotrimer composed of scaffolding (A), catalytic (C), and regulatory (B) subunits with various key roles during cell division. While A and C subunits form the core enzyme, the diversity generated by interchangeable B subunits dictates substrate specificity. Within the B subunits, B56-type subunits play important roles during meiosis in yeast and mice by protecting centromeric cohesion and stabilising the kinetochore-microtubule attachments. These functions are achieved through targeting of B56 subunits to centromere and kinetochore by Shugoshin and BUBR1. In the nematode Caenorhabditis elegans (C. elegans) the closest BUBR1 ortholog lacks the B56 interaction domain and the Shugoshin orthologue is not required for normal segregation during oocyte meiosis. Therefore, the role of PP2A in C. elegans female meiosis is not known. Here, we report that PP2A is essential for meiotic spindle assembly and chromosome dynamics during C. elegans female meiosis. Specifically, B56 subunits PPTR-1 and PPTR-2 associate with chromosomes during prometaphase I and regulate chromosome congression. The chromosome localization of B56 subunits does not require shugoshin orthologue SGO-1. Instead we have identified the kinase BUB-1 as the key B56 targeting factor to the chromosomes during meiosis. PP2A BUB-1 recruits PP2A:B56 to the chromosomes via dual mechanism: 1) PPTR-1/2 interacts with the newly identified LxxIxE short linear motif (SLiM) within a disordered region in BUB-1 in a phosphorylation-dependent manner; and 2) PPTR-2 can also be recruited to chromosomes in a BUB-1 kinase domain-dependent manner. Our results highlight a novel, BUB-1-dependent mechanism for B56 recruitment, essential for recruiting a pool of PP2A required for proper chromosome congression during meiosis I.

cell biology↗

bioRxiv2019

Sumoylation regulates central spindle protein dynamics during chromosome segregation in oocyte

Meiotic spindles in most species lack centrosomes and the mechanisms that underlie faithful chromosome segregation in acentrosomal meiotic spindles are not well understood. In C. elegans oocytes, spindle microtubules exert a poleward force on chromosomes dependent on the microtubule-stabilising protein CLS-2CLASP. The kinase BUB-1Bub1 and CLS-2CLASP localise in the central-spindle and display a dynamic localisation pattern throughout anaphase but the signals regulating their anaphase-specific localisation remains unknown. We have shown that SUMO regulates BUB-1 localisation during metaphase I. Here, we found that SUMO modification of BUB-1Bub1 is regulated by the SUMO E3 ligase GEI-17 and the SUMO protease ULP-1. SUMO is required for BUB-1 localisation in between segregating chromosomes during early anaphase I, and SUMO depletion partially phenocopies BUB-1Bub1 depletion. We also show that CLS-2CLASP is subject to SUMO-mediated regulation. Over-all, we provide evidence for a novel, SUMO-mediated control of protein dynamics during early anaphase I in oocytes.

cell biology↗