Practice question

Centrosome duplication must occur once per cell cycle mirroring DNA replication to ensure formation of exactly two spindle poles. CDK2-Cyclin E in G1/S licenses disengagement of mother-daughter centrioles, while CDK1-Cyclin B, Polo-like kinase 1 and Aurora A coordinate maturation and separation later. Plk1 accumulates during G2, localizes to centrosomes via Polo-box binding to CEP192 phosphorylated by CDK1, and phosphorylates pericentrin, CEP215, NEDD9 enhancing recruitment of gamma-tubulin ring complexes and expanding pericentriolar material volume up to fivefold. Aurora A becomes active through autophosphorylation at Thr288 stimulated by TPX2 binding microtubules, subsequently phosphorylates TACC3 and ch-TOG stabilizing centrosomal microtubules and activates LATS2. It also phosphorylates Eg5 kinesin promoting bipolarity. Together kinases drive dissolution of intercentrosomal linker proteins, PCM maturation increasing nucleation capacity, and separation to opposite sides of nucleus mediated by Eg5 pushing forces. Dysregulation causes supernumerary centrosomes, multipolar spindles and aneuploidy frequently observed in tumors, linking kinase coordination to genome stability. Additional feedback loops involving polo-like kinases, phosphatases and SCF-mediated degradation reinforce irreversibility and protect against premature progression that would compromise genome integrity and viability.