title: Yeast haspin kinase regulates polarity cues necessary for mitotic spindle positioning and is required to tolerate mitotic arrest.
abstract: Haspin is an atypical protein kinase that in several organisms phosphorylates histone H3Thr3 and is involved in chromosome segregation. In Saccharomyces cerevisiae, H3Thr3 phosphorylation has never been observed and the function of haspin is unknown. We show that deletion of ALK1 and ALK2 haspin paralogs causes the mislocalization of polarisome components. Following a transient mitotic arrest, this leads to an overly polarized actin distribution in the bud where the mitotic spindle is pulled. Here it elongates, generating anucleated mothers and binucleated daughters. Reducing the intensity of the bud-directed pulling forces partially restores proper cell division. We propose that haspin controls the localization of polarity cues to preserve the coordination between polarization and the cell cycle and to tolerate transient mitotic arrests. The evolutionary conservation of haspin and of the polarization mechanisms suggests that this function of haspin is likely shared with other eukaryotes, in which haspin may regulate asymmetric cell division.
authors: Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy.
authors: Davide
authors: D
authors: Panigada
authors: Paolo
authors: P
authors: Grianti
authors: Alessandro
authors: A
authors: Nespoli
authors: Giuseppe
authors: G
authors: Rotondo
authors: Daniela Gallo
authors: DG
authors: Castro
authors: Roberto
authors: R
authors: Quadri
authors: Simonetta
authors: S
authors: Piatti
authors: Paolo
authors: P
authors: Plevani
authors: Marco
authors: M
authors: Muzi-Falconi
mesh_terms: D059447:Cell Cycle Checkpoints / Q000235:genetics; D016764:Cell Polarity / Q000235:genetics; D020090:Chromosome Segregation / Q000235:genetics; D006657:Histones / Q000235:genetics / Q000378:metabolism; D008870:Microtubules / Q000235:genetics; D008938:Mitosis / Q000235:genetics*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*; D008941:Spindle Apparatus / Q000235:genetics*
chemical_list: D006657:Histones; D029701:Saccharomyces cerevisiae Proteins; C515738:Alk1 protein, S cerevisiae; C515739:Alk2 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; C584827:haspin kinase, S cerevisiae