Dynamics of Cell Division
Cell division requires the proper spatio-temporal coordination between mitosis and citokinesis to allow the correct inheritance of the genetic material. Eukaryotic cells assemble the mitotic spindle to permit chromosome segregation into the daughter cells. The spindle in a structure made on microtubules, which are polarized and highly dynamic cytoskeletal filaments. The major functions of the spindle are to properly capture chromosomes and to become a bipolar structure that allows their segregation into the daughter cells during cell division. Molecular motors play a critical role in the initial organization of the spindle; in particular, the kinesin-5 family has emerged as essential proteins for spindle assembly in most eukaryotic systems. Nevertheless, it has recently been shown that spindle bipolarity can be achieved independently of any motor activity, indicating the existence of parallel, redundant pathways. In animal and fungal cells, spindle assembly and dynamics are intimately coordinated with the formation of the acto-myosin contractile ring, a circular structure associated to the plasma membrane whose constriction allows the physical separation of the two daughter cells. While the signaling pathways that drive acto-myosin ring assembly and constriction have been thoroughly studied, the inputs from the mitotic spindle are missing.
Using the fission yeast Schizosaccharomyces pombe as a model system, we propose to investigate the process of mitotic spindle and contractile ring assembly and the patio-temporal feedback between both structures that allow successful cell division. Taking advantage of the stereotyped mitosis progression of the fission yeast, we will use time-lapse microscopy to investigate the sequential order of protein recruitment to the mitotic machinery and their genetic dependencies. In a genome-wide approach we will look for the parallel pathways that contribute to spindle assembly independently of kinesin-5.
The molecular machineries involved in mitotic spindle and contractile ring assembly are highly conserved along evolution, from yeasts to metazoans. Defective dynamics of these structures may result in problems in the segregation of the genetic material, being the cause of aneuploidy, or incorrect chromosome segregation. Aneuploidy is a hallmark of cancer, therefore, providing this line of research definitely an applied spirit.
(A) Time-lapse images of wild-type (wt) and cut7Δpkl1Δ cells expressing mCherry-Atb2 (tubulin) and Sid4-GFP (spindle pole marker) from mitosis onset to spindle breakdown. Each frame corresponds to 3 minutes interval. Scale bar, 2 μm.
(B) Comparative plot of spindle length dynamics of wild-type (green curves; n=19) and cut7Δpkl1Δ cells (red curves; n=24). Dotted vertical line corresponds to phase I to phase II transition; dashed vertical line corresponds to phase II to phase III transition.
(C) Time-lapse images of mitotic cells expressing mCherry-Atb2 and Cut11-GFP (nuclear envelope). Each frame corresponds to 5 minutes interval.
|Sergio Rincón||Principal Investigator|
|David Martínez Delgado||Internship technician|
|Shara Tello García||Internship technician|
|Rincon SA, Lamson A, Blackwell R, Syrovatkina V, Fraisier V, Paoletti A, Betterton MD, Tran PT. (2017)
Kinesin-5-independent mitotic spindle assembly requires on the antiparallel microtubule crosslinker Ase1 in fission yeast.
Nat Commun 8:15286
| Rincon SA, Paoletti A. (2016)
Molecular control of fission yeast cytokinesis
Semin Cell Dev Biol 53, 28-38
| Rincon SA*, Estravis M, Dingli F, Loew D, Tran PT, Paoletti A*. (2017)
SIN-dependent dissociation of the SAD kinase Cdr2 from the cell cortex resets the division plane
Curr Biol 27(4):534-542. (* co-corresponding authors)
| Estravís M, Rincón SA, Portales E, Pérez P, Santos B. (2017)
Cdc42 activation state affects its localization and protein levels in fission yeast.
| Guzmán-Vendrell M, Rincon SA, Dingli F, Loew D, Paoletti A. (2015)
Molecular control of the Wee1 regulatory pathway by the SAD kinase Cdr2
J Cell Sci 128, 2842-53
| Rincon SA, Bhatia P, Bicho C, Guzman-Vendrell M, Fraisier V, Borek WE, Lima-Alves F, Dingli F, Loew D, Rappsilber J, Sawin KE, Martin SG, Paoletti A. (2014)
Pom1 regulates the assembly of Cdr2-Mid1 cortical nodes for robust spatial control of cytokinesis
J Cell Biol 206, 61-77
| Bhatia P, Hachet O*, Hersch M*, Rincon SA*, Berthelot-Grosjean M, Dalessi S, Basterra L, Bergmann S, Paoletti A, Martin SG. (2014)
Distinct levels in Pom1 gradients limit Cdr2 activity and localization to time and position division
Cell Cycle 13, 538-52. (*equal contribution)
| Rincón SA, Estravís M, Pérez P. (2014)
Cdc42 regulates polarized growth and cell integrity in fission yeast
Biochem Soc Trans 42, 201-5