γ-Tubulin is a centrosomal protein required for cell cycle-dependent microtubule nucleation

The centrosome contains proteins that control the organization of the microtubule cytoskeleton in interphase and mitosis. Its protein composition is tightly regulated through selective and cell cycle–dependent recruitment, retention, and removal of components. However, the mechanisms underlying protein delivery to the centrosome are not completely understood. We describe a novel function for the polarity protein Par6α in protein transport to the centrosome. We detected Par6α at the centrosome and centriolar satellites where it interacted with the centriolar satellite protein PCM-1 and the dynactin subunit p150Glued. Depletion of Par6α caused the mislocalization of p150Glued and centrosomal components that are critical for microtubule anchoring at the centrosome. As a consequence, there were severe alterations in the organization of the microtubule cytoskeleton in the absence of Par6α and cell division was blocked. We propose a model in which Par6α controls centrosome organization through its association with the dynactin subunit p150Glued.

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Cell-cycle dependent phosphorylation of yeast pericentrin regulates γ-TuSC-mediated microtubule nucleation

eLife ◽

10.7554/elife.02208 ◽

2014 ◽

Vol 3 ◽

Cited By ~ 59

Author(s):

Tien-chen Lin ◽

Annett Neuner ◽

Yvonne T Schlosser ◽

Annette ND Scharf ◽

Lisa Weber ◽

...

Keyword(s):

Cell Cycle ◽

Molecular Basis ◽

Dependent Manner ◽

Microtubule Nucleation ◽

Biochemical Studies ◽

N Terminus ◽

Complex Receptor ◽

A Cell ◽

Cycle Dependent ◽

Receptor Family

Budding yeast Spc110, a member of γ-tubulin complex receptor family (γ-TuCR), recruits γ-tubulin complexes to microtubule (MT) organizing centers (MTOCs). Biochemical studies suggest that Spc110 facilitates higher-order γ-tubulin complex assembly (<xref ref-type="bibr" rid="bib45">Kollman et al., 2010</xref>). Nevertheless the molecular basis for this activity and the regulation are unclear. Here we show that Spc110 phosphorylated by Mps1 and Cdk1 activates γ-TuSC oligomerization and MT nucleation in a cell cycle dependent manner. Interaction between the N-terminus of the γ-TuSC subunit Spc98 and Spc110 is important for this activity. Besides the conserved CM1 motif in γ-TuCRs (<xref ref-type="bibr" rid="bib65">Sawin et al., 2004</xref>), a second motif that we named Spc110/Pcp1 motif (SPM) is also important for MT nucleation. The activating Mps1 and Cdk1 sites lie between SPM and CM1 motifs. Most organisms have both SPM-CM1 (Spc110/Pcp1/PCNT) and CM1-only (Spc72/Mto1/Cnn/CDK5RAP2/myomegalin) types of γ-TuCRs. The two types of γ-TuCRs contain distinct but conserved C-terminal MTOC targeting domains.

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PCM-1, A 228-kD centrosome autoantigen with a distinct cell cycle distribution

The Journal of Cell Biology ◽

10.1083/jcb.124.5.783 ◽

1994 ◽

Vol 124 (5) ◽

pp. 783-793 ◽

Cited By ~ 90

Author(s):

R Balczon ◽

L Bao ◽

WE Zimmer

Keyword(s):

Cell Cycle ◽

Immunofluorescence Microscopy ◽

G1 Phase ◽

Cell Cycle Distribution ◽

Primary Sequence ◽

Centrosomal Protein ◽

Distinct Cell ◽

Pericentriolar Material ◽

Cycle Dependent

We report the identification and primary sequence of PCM-1, a 228-kD centrosomal protein that exhibits a distinct cell cycle-dependent association with the centrosome complex. Immunofluorescence microscopy using antibodies against recombinant PCM-1 demonstrated that PCM-1 is tightly associated with the centrosome complex through G1, S, and a portion of G2. However, late in G2, as cells prepare for mitosis, PCM-1 dissociates from the centrosome and then remains dispersed throughout the cell during mitosis before re-associating with the centrosomes in the G1 phase progeny cells. These results demonstrate that the pericentriolar material is a dynamic substance whose composition can fluctuate during the cell cycle.

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