Plk1 promotes disengagement and reduplication of structurally immature procentrioles

Thursday, November 07, 2013 — Poster Session II
12:00 p.m. – 2:00 p.m.	FAES Academic Center (Upper-Level Terrace)	NCI	CHEMCELL-10

Authors

D. Kong
J. Loncarek

Abstract

Last step of centriole cycle is centriole disengagement which occurs during late stages of mitosis. During disengagement mother and almost fully grown daughter centriole separate to form independent centrosomes in the next G1. Mitotic kinase Plk1 promotes centriole disengagement in mitosis. However, elevated Plk1 activity can result in premature centriole disengagement during interphase. Molecular mechanisms leading to this phenotype are largely unknown. This study is testing a hypothesis that structural maturation of procentrioles is a prerequisite for their disengagement. As a model we are using endocycling Emi1-depleted U2OS and HeLa cells engineered to express Plk1 upon doxycycline treatment. Without Plk1 induction, mother centrioles of Emi1-depleted cells are duplicated and engaged to a short immature procentriole. Light and electron microscopy analysis showed that in Plk1 expressing Emi1-depleted cells such short procentrioles can disengage from their mothers. Intriguingly, many disengaged short procentrioles were able to duplicate and develop appendage-like structures with time, but they never reach a full length. Our study demonstrates that the ability of procentrioles to complete their cycle (to disengage and duplicate) is not dependent on their length, but is rather dependent on some yet unidentified biochemical qualities.