A homeostatic clock sets daughter centriole size in flies

Centrioles are highly structured organelles whose size is remarkably consistent within any given cell type. New centrioles are born when Polo-like kinase 4 (Plk4) recruits Ana2/STIL and Sas-6 to the side of an existing “mother” centriole. These two proteins then assemble into a cartwheel, which grows outwards to form the structural core of a new daughter. Here, we show that in early Drosophila melanogaster embryos, daughter centrioles grow at a linear rate during early S-phase and abruptly stop growing when they reach their correct size in mid- to late S-phase. Unexpectedly, the cartwheel grows from its proximal end, and Plk4 determines both the rate and period of centriole growth: the more active the centriolar Plk4, the faster centrioles grow, but the faster centriolar Plk4 is inactivated and growth ceases. Thus, Plk4 functions as a homeostatic clock, establishing an inverse relationship between growth rate and period to ensure that daughter centrioles grow to the correct size

A homeostatic clock sets daughter centriole size in flies

Centrioles are highly structured organelles whose size is remarkably consistent within any given cell type. New centrioles are born when Polo-like kinase 4 (Plk4) recruits Ana2/STIL and Sas-6 to the side of an existing “mother” centriole. These two proteins then assemble into a cartwheel, which grows outwards to form the structural core of a new daughter. Here, we show that in early Drosophila melanogaster embryos, daughter centrioles grow at a linear rate during early S-phase and abruptly stop growing when they reach their correct size in mid- to late S-phase. Unexpectedly, the cartwheel grows from its proximal end, and Plk4 determines both the rate and period of centriole growth: the more active the centriolar Plk4, the faster centrioles grow, but the faster centriolar Plk4 is inactivated and growth ceases. Thus, Plk4 functions as a homeostatic clock, establishing an inverse relationship between growth rate and period to ensure that daughter centrioles grow to the correct size

Propagation d'ondes dans des structures a GAP photonique : une comparaison entre calcul numerique et resultats experimentaux

Communication to : 'JCMM98', 5emes journees de caracterisation micro-onde et materiaux, Le Touquet (France), 13-15 mai 1998SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.1998 n.63 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

An autonomous oscillator times and executes centriole biogenesis

The accurate timing and execution of organelle biogenesis is crucial for cell physiology. Centriole biogenesis is regulated by Polo-like kinase 4 (Plk4) and initiates in S-phase when a daughter centriole grows from the side of a preexisting mother. Here we show that Plk4 forms an adaptive oscillator at the base of the growing centriole to initiate and time centriole biogenesis, ensuring that centrioles grow at the right time and to the right size. The Plk4 oscillator is normally entrained to the cell-cycle oscillator, but can run autonomously of it – explaining how centrioles can duplicate independently of cell cycle progression under certain conditions. Mathematical modelling indicates that this autonomously oscillating system is generated by a time-delayed negative-feedback loop in which Plk4 inactivates its centriolar receptor through multiple rounds of phosphorylation. We postulate that such organelle-specific autonomous oscillators could regulate the timing and execution of organelle biogenesis more generally

An autonomous oscillator times and executes centriole biogenesis

The accurate timing and execution of organelle biogenesis is crucial for cell physiology. Centriole biogenesis is regulated by Polo-like kinase 4 (Plk4) and initiates in S-phase when a daughter centriole grows from the side of a preexisting mother. Here we show that Plk4 forms an adaptive oscillator at the base of the growing centriole to initiate and time centriole biogenesis, ensuring that centrioles grow at the right time and to the right size. The Plk4 oscillator is normally entrained to the cell-cycle oscillator, but can run autonomously of it – explaining how centrioles can duplicate independently of cell cycle progression under certain conditions. Mathematical modelling indicates that this autonomously oscillating system is generated by a time-delayed negative-feedback loop in which Plk4 inactivates its centriolar receptor through multiple rounds of phosphorylation. We postulate that such organelle-specific autonomous oscillators could regulate the timing and execution of organelle biogenesis more generally

An autonomous oscillation times and executes centriole biogenesis

The accurate timing and execution of organelle biogenesis is crucial for cell physiology. Centriole biogenesis is regulated by Polo-like kinase 4 (Plk4) and initiates in S-phase when a daughter centriole grows from the side of a pre-existing mother. Here, we show that a Plk4 oscillation at the base of the growing centriole initiates and times centriole biogenesis to ensure that centrioles grow at the right time and to the right size. The Plk4 oscillation is normally entrained to the cell-cycle oscillator but can run autonomously of it—potentially explaining why centrioles can duplicate independently of cell-cycle progression. Mathematical modeling indicates that the Plk4 oscillation can be generated by a time-delayed negative feedback loop in which Plk4 inactivates the interaction with its centriolar receptor through multiple rounds of phosphorylation. We hypothesize that similar organelle-specific oscillations could regulate the timing and execution of organelle biogenesis more generally