Proper orientation of the mitotic spindle is critical for accurate development and morphogenesis. In human cells, spindle orientation is regulated by the evolutionarily conserved protein NuMA, which interacts with dynein and enriches it at the cell cortex. Pulling forces generated by cortical dynein orient the mitotic spindle. Cdk1-mediated phosphorylation of NuMA at threonine 2055 (T2055) negatively regulates its cortical localization. Thus, only NuMA not phosphorylated at T2055 localizes at the cell cortex. However, the identity and the mechanism of action of the phosphatase complex involved in T2055 dephosphorylation remains elusive. Here, we characterized the PPP2CA-B55γ (PPP2R2C)-PPP2R1B complex that counteracts Cdk1 to orchestrate cortical NuMA for proper spindle orientation. reconstitution experiments revealed that this complex is sufficient for T2055 dephosphorylation. Importantly, we identified polybasic residues in NuMA that are critical for T2055 dephosphorylation, and for maintaining appropriate cortical NuMA levels for accurate spindle elongation. Furthermore, we found that Cdk1-mediated phosphorylation and PP2A-B55γ-mediated dephosphorylation at T2055 are reversible events. Altogether, this study uncovers a novel mechanism by which Cdk1 and its counteracting PP2A-B55γ complex orchestrate spatiotemporal levels of cortical force generators for flawless mitosis.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7406356 | PMC |
| http://dx.doi.org/10.1242/jcs.243857 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
The role of Golgi complex proteins in cell division and consequences of their dysregulation.
Front Cell Dev Biol
January 2025
Department of Biomedical Sciences (DSB), Institute of Experimental Endocrinology and Oncology "G. Salvatore" (IEOS), National Research Council (CNR), Naples, Italy.
The GC (Golgi complex) plays a pivotal role in the trafficking and sorting of proteins and lipids until they reach their final destination. Additionally, the GC acts as a signalling hub to regulate a multitude of cellular processes, including cell polarity, motility, apoptosis, DNA repair and cell division. In light of these crucial roles, the GC has garnered increasing attention, particularly given the evidence that a dysregulation of GC-regulated signalling pathways may contribute to the onset of various pathological conditions.
View Article and Find Full Text PDFAltered cytoskeleton dynamics in patient-derived iPSC-based model of PCDH19 clustering epilepsy.
Front Cell Dev Biol
January 2025
Molecular Genetics and Functional Genomics, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy.
Protocadherin 19 (PCDH19) is an adhesion molecule involved in cell-cell interaction whose mutations cause a drug-resistant form of epilepsy, named PCDH19-Clustering Epilepsy (PCDH19-CE, MIM 300088). The mechanism by which altered PCDH19 function drive pathogenesis is not yet fully understood. Our previous work showed that PCDH19 dysfunction is associated with altered orientation of the mitotic spindle and accelerated neurogenesis, suggesting a contribution of altered cytoskeleton organization in PCDH19-CE pathogenesis in the control of cell division and differentiation.
View Article and Find Full Text PDFCAMSAP2 is required for bridging fiber assembly to ensure mitotic spindle assembly and chromosome segregation in human epithelial Caco-2 cells.
PLoS One
January 2025
Department of Life Science and Medical Bioscience, Laboratory of Cytoskeletal Logistics, Graduate School of Advanced Science and Engineering, Waseda University, Shinjuku, Tokyo, Japan.
In mammalian epithelial cells, cytoplasmic microtubules are mainly non-centrosomal, through the functions of the minus-end binding proteins CAMSAP2 and CAMSAP3. When cells enter mitosis, cytoplasmic microtubules are reorganized into the spindle composed of both centrosomal and non-centrosomal microtubules. The function of the CAMSAP proteins upon spindle assembly remains unknown, as these do not exhibit evident localization to spindle microtubules.
View Article and Find Full Text PDFCellular EMT-status governs contact guidance in an electrospun TACS-mimicking model.
Mater Today Bio
February 2025
Pharmaceutical Technology and Biopharmaceutics, Department of Pharmacy, Ludwig-Maximilians-University München, Munich, Germany.
In this study, an advanced nanofiber breast cancer model was developed and systematically characterized including physico-chemical, cell-biological and biophysical parameters. Using electrospinning, the architecture of tumor-associated collagen signatures (TACS5 and TACS6) was mimicked. By employing a rotating cylinder or static plate collector set-up, aligned fibers (TACS5-like structures) and randomly orientated fibers (TACS6-like structures) fibers were produced, respectively.
View Article and Find Full Text PDFCell shape modulates mitotic spindle positioning forces via intracellular hydrodynamics.
Curr Biol
January 2025
Université Paris Cité, CNRS, Institut Jacques Monod, 75013 Paris, France; Equipe Labellisée LIGUE Contre le Cancer, 75013 Paris, France. Electronic address:
The regulation of mitotic spindle positioning and orientation is central to the morphogenesis of developing embryos and tissues. In many multicellular contexts, cell geometry has been shown to have a major influence on spindle positioning, with spindles that commonly align along the longest cell shape axis. To date, however, we still lack an understanding of how the nature and amplitude of intracellular forces that position, orient, or hold mitotic spindles depend on cell geometry.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!