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The de novo centriole assembly pathway in HeLa cells: cell cycle progression and centriole assembly/maturation.

La Terra S, English CN, Hergert P, McEwen BF, Sluder G, Khodjakov A - J. Cell Biol. (2005)

Bottom Line: Here, we show that removal of resident centrioles (by laser ablation or needle microsurgery) does not impede cell cycle progression in HeLa cells.This maturation is not simply a time-dependent phenomenon, because de novo-formed centrioles do not mature if they are assembled in S phase-arrested cells.By selectively ablating only one centriole at a time, we find that the presence of a single centriole inhibits the assembly of additional centrioles, indicating that centrioles have an activity that suppresses the de novo pathway.

View Article: PubMed Central - PubMed

Affiliation: Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA.

ABSTRACT
It has been reported that nontransformed mammalian cells become arrested during G1 in the absence of centrioles (Hinchcliffe, E., F. Miller, M. Cham, A. Khodjakov, and G. Sluder. 2001. Science. 291:1547-1550). Here, we show that removal of resident centrioles (by laser ablation or needle microsurgery) does not impede cell cycle progression in HeLa cells. HeLa cells born without centrosomes, later, assemble a variable number of centrioles de novo. Centriole assembly begins with the formation of small centrin aggregates that appear during the S phase. These, initially amorphous "precentrioles" become morphologically recognizable centrioles before mitosis. De novo-assembled centrioles mature (i.e., gain abilities to organize microtubules and replicate) in the next cell cycle. This maturation is not simply a time-dependent phenomenon, because de novo-formed centrioles do not mature if they are assembled in S phase-arrested cells. By selectively ablating only one centriole at a time, we find that the presence of a single centriole inhibits the assembly of additional centrioles, indicating that centrioles have an activity that suppresses the de novo pathway.

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Related in: MedlinePlus

Timeline of centrosome reformation in HeLa cells. When a cell is born without centrioles, it continues to progress through the cell cycle with normal kinetics. When cells enter S phase, multiple aggregates of centrin (precentrioles, small green dots) form. These precentrioles transform into morphologically complete centrioles (green open circles) by the time the cell enters its first mitosis. However, de novo–formed centrioles do not mature centrosomes until the ensuing G1 in the second cell cycle. As cell enters the second cell cycle S phase, de novo–formed centrioles replicate and normal centriolar cycles resume.
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fig10: Timeline of centrosome reformation in HeLa cells. When a cell is born without centrioles, it continues to progress through the cell cycle with normal kinetics. When cells enter S phase, multiple aggregates of centrin (precentrioles, small green dots) form. These precentrioles transform into morphologically complete centrioles (green open circles) by the time the cell enters its first mitosis. However, de novo–formed centrioles do not mature centrosomes until the ensuing G1 in the second cell cycle. As cell enters the second cell cycle S phase, de novo–formed centrioles replicate and normal centriolar cycles resume.

Mentions: Our finding of de novo centriole formation in cycling cells allowed us to follow the development of centrioles from birth to maturity in the absence of resident mother centrioles whose activities could potentially influence the maturation of the daughters. We observed three distinct stages of the centriole development: (1) formation of centrin aggregates (precentrioles); (2) assembly of the 9 triplet microtubules to form morphologically complete centrioles; and (3) centriole maturation (Fig. 10). We find that formation of precentrioles is first manifested as aggregation of centrin, a protein present in the centriolar lumen and required for centriole replication (Paoletti et al., 1996; Middendorp et al., 1997). Centrin is abundant in cells and only <10% of the total centrin is associated with the centrosome (Paoletti et al., 1996). Since centrin shows no tendency to aggregate when overexpressed, it is likely that the precentriole formation is seeded by other components such as the centrin-binding protein Sfi1p (Kilmartin, 2005).


The de novo centriole assembly pathway in HeLa cells: cell cycle progression and centriole assembly/maturation.

La Terra S, English CN, Hergert P, McEwen BF, Sluder G, Khodjakov A - J. Cell Biol. (2005)

Timeline of centrosome reformation in HeLa cells. When a cell is born without centrioles, it continues to progress through the cell cycle with normal kinetics. When cells enter S phase, multiple aggregates of centrin (precentrioles, small green dots) form. These precentrioles transform into morphologically complete centrioles (green open circles) by the time the cell enters its first mitosis. However, de novo–formed centrioles do not mature centrosomes until the ensuing G1 in the second cell cycle. As cell enters the second cell cycle S phase, de novo–formed centrioles replicate and normal centriolar cycles resume.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2171814&req=5

fig10: Timeline of centrosome reformation in HeLa cells. When a cell is born without centrioles, it continues to progress through the cell cycle with normal kinetics. When cells enter S phase, multiple aggregates of centrin (precentrioles, small green dots) form. These precentrioles transform into morphologically complete centrioles (green open circles) by the time the cell enters its first mitosis. However, de novo–formed centrioles do not mature centrosomes until the ensuing G1 in the second cell cycle. As cell enters the second cell cycle S phase, de novo–formed centrioles replicate and normal centriolar cycles resume.
Mentions: Our finding of de novo centriole formation in cycling cells allowed us to follow the development of centrioles from birth to maturity in the absence of resident mother centrioles whose activities could potentially influence the maturation of the daughters. We observed three distinct stages of the centriole development: (1) formation of centrin aggregates (precentrioles); (2) assembly of the 9 triplet microtubules to form morphologically complete centrioles; and (3) centriole maturation (Fig. 10). We find that formation of precentrioles is first manifested as aggregation of centrin, a protein present in the centriolar lumen and required for centriole replication (Paoletti et al., 1996; Middendorp et al., 1997). Centrin is abundant in cells and only <10% of the total centrin is associated with the centrosome (Paoletti et al., 1996). Since centrin shows no tendency to aggregate when overexpressed, it is likely that the precentriole formation is seeded by other components such as the centrin-binding protein Sfi1p (Kilmartin, 2005).

Bottom Line: Here, we show that removal of resident centrioles (by laser ablation or needle microsurgery) does not impede cell cycle progression in HeLa cells.This maturation is not simply a time-dependent phenomenon, because de novo-formed centrioles do not mature if they are assembled in S phase-arrested cells.By selectively ablating only one centriole at a time, we find that the presence of a single centriole inhibits the assembly of additional centrioles, indicating that centrioles have an activity that suppresses the de novo pathway.

View Article: PubMed Central - PubMed

Affiliation: Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA.

ABSTRACT
It has been reported that nontransformed mammalian cells become arrested during G1 in the absence of centrioles (Hinchcliffe, E., F. Miller, M. Cham, A. Khodjakov, and G. Sluder. 2001. Science. 291:1547-1550). Here, we show that removal of resident centrioles (by laser ablation or needle microsurgery) does not impede cell cycle progression in HeLa cells. HeLa cells born without centrosomes, later, assemble a variable number of centrioles de novo. Centriole assembly begins with the formation of small centrin aggregates that appear during the S phase. These, initially amorphous "precentrioles" become morphologically recognizable centrioles before mitosis. De novo-assembled centrioles mature (i.e., gain abilities to organize microtubules and replicate) in the next cell cycle. This maturation is not simply a time-dependent phenomenon, because de novo-formed centrioles do not mature if they are assembled in S phase-arrested cells. By selectively ablating only one centriole at a time, we find that the presence of a single centriole inhibits the assembly of additional centrioles, indicating that centrioles have an activity that suppresses the de novo pathway.

Show MeSH
Related in: MedlinePlus