The function of mammalian Polo-like kinase 1 in microtubule nucleation

Abstract

Mitotic spindle, the structure essential for equal partitioning of the chromosomes into daughter cells, is of pivotal importance for the maintenance of genomic stability during cell division (1). Microtubules (MTs) that constitute the mitotic spindle are polymers of α- and β-tubulin dimers. Generation of MT starts with a process called MT nucleation in which tubulin dimers polymerize (2). An MT is typically nucleated at an MT organizing center (MTOC) that includes centrosomes and kinetochores/chromatin (2, 3). Emerging evidence indicates that an MT is capable of functioning as an additional MTOC independent of the centrosome. The initial evidence that MT arrays could originate from preexisting MTs came from the observation that EB1-GFP, an ectopically expressed MT plus end binding protein, was localized to acentrosomal spindles (4). The notion was additionally supported by several subsequent studies (3, 5, 6). Growing evidence suggests that MT-dependent MT nucleation has its unique features that are not shared by MT nucleation processes occurring at centrosome or kinetochore/chromatin (3, 5, 6).