| 2005 |
HsSAS-6 (SASS6) localizes to centrosomes and is required for centrosome duplication in human cells: siRNA-mediated inactivation in U2OS cells abrogates centrosome overduplication following aphidicolin treatment and interferes with the normal centrosome duplication cycle. In C. elegans, SAS-6 is recruited to centrioles at the onset of the centrosome duplication cycle, associates with SAS-5, and requires both the SAS-5 interaction and ZYG-1 function for centriolar recruitment. |
siRNA knockdown in human U2OS cells, GFP localization, C. elegans genetics, co-immunoprecipitation |
Nature cell biology |
High |
15665853
|
| 2007 |
In Chlamydomonas, SAS-6 localizes to the central part of the cartwheel and is required to establish nine-fold centriolar symmetry. A null mutant (bld12) lacking the cartwheel central part frequently produces centrioles with non-canonical triplet numbers (7, 8, 10, or 11), demonstrating that SAS-6 is an essential cartwheel component that stabilizes the 9-triplet structure. |
Chlamydomonas null mutant analysis, electron microscopy, immunolocalization |
Current biology : CB |
High |
18082404
|
| 2009 |
The kinase ZYG-1 phosphorylates SAS-6 at serine 123 in vitro, and this phosphorylation event is critical for centriole formation in C. elegans embryos in vivo. Phosphorylation ensures maintenance of SAS-6 at the emerging centriole. |
In vitro kinase assay, C. elegans genetics with phospho-mutant rescue, fluorescence microscopy |
Developmental cell |
High |
20059959
|
| 2010 |
Drosophila SAS-6 self-assembles into stable tetramers in vitro, which serve as building blocks for the central tubule of the centriolar cartwheel. SAS-6 concentrates at the core of the cartwheel, and elevated SAS-6 levels in Drosophila cells produce higher-order structures resembling central tubule morphology. |
Biochemistry (gel filtration, native PAGE), electron microscopy of centrosomes and recombinant protein, cell overexpression |
The Journal of biological chemistry |
Medium |
20083610
|
| 2011 |
X-ray crystal structure of the zebrafish SAS-6 N-terminal domain reveals that recombinant SAS-6 self-associates in vitro into assemblies resembling cartwheel centers. Point mutations disrupting the self-assembly interfaces impair centriole formation in vivo, establishing that these interactions are essential for cartwheel center organization. |
X-ray crystallography, in vitro reconstitution, point mutagenesis with in vivo centriole formation assay |
Science (New York, N.Y.) |
High |
21273447
|
| 2013 |
In C. elegans, ZYG-1 recruits SAS-6 to the mother centriole via a direct binding interaction between ZYG-1 and the SAS-6 coiled coil, independently of ZYG-1 kinase activity. Separately, an adjacent segment of the SAS-6 coiled coil interacts with SAS-5, and both interactions are required for SAS-6 recruitment and cartwheel assembly. ZYG-1 kinase activity is subsequently required for cartwheel assembly, but its essential substrate is unlikely to be SAS-6 itself. |
Pulldown, co-immunoprecipitation, in vitro binding assays, C. elegans genetics with alanine-substitution mutants |
Developmental cell |
High |
23673331
|
| 2013 |
C. elegans SAS-6 self-assembles into a spiral arrangement (rather than rings) as shown by crystallography and EM, yet this spiral is consistent with nine-fold symmetry, suggesting two distinct SAS-6 oligomerization architectures can direct the same output symmetry. Spiral arrangement is correlated with the presence of a central tube instead of a cartwheel in nematode centriole assembly. |
X-ray crystallography, electron microscopy |
Proceedings of the National Academy of Sciences of the United States of America |
High |
23798409
|
| 2014 |
Drosophila Plk4 phosphorylates four conserved serines in the STAN motif of Ana2 (STIL ortholog) to enable Ana2 to bind and recruit its Sas6 partner. Non-phosphorylatable Ana2 localizes to the centriole but cannot recruit Sas6, causing failure of centriole duplication. Thus, Plk4-mediated phosphorylation of Ana2/STIL is the earliest upstream step for Sas6 recruitment and procentriole architecture establishment. |
In vitro kinase assay, Drosophila genetics with phospho-mutant rescue, live imaging, immunofluorescence |
Current biology : CB |
High |
25264260
|
| 2014 |
Leishmania major SAS-6 crystallizes as a nine-fold symmetric cartwheel, providing a 3.5 Å X-ray structure of this assembly and firmly establishing that SAS-6 self-assembly alone can impose cartwheel symmetry. Small-molecule inhibition of SAS-6 oligomerization is feasible in vitro. |
X-ray crystallography at 3.5 Å, in vitro small-molecule inhibition assay |
eLife |
High |
24596152
|
| 2014 |
During S phase, SAS-6 molecules are first recruited to the proximal lumen of the mother centriole, adopting a cartwheel-like organization through interactions with the luminal wall rather than via self-oligomerization. Removal/release of luminal SAS-6 requires Plk4 and STIL. Abolishing either recruitment or removal of luminal SAS-6 hinders SAS-6/centriole assembly at the outside wall. After duplication, the lumen of engaged mother centrioles becomes inaccessible to SAS-6, correlating with a block for reduplication. |
Live cell fluorescence microscopy, siRNA knockdown, structured illumination microscopy |
Developmental cell |
Medium |
25017693
|
| 2015 |
The C-terminal tail of human SAS-6 (residues 470–657) nucleates and promotes microtubule polymerization in vitro, binds to microtubules along their lengths, and interacts with α/β-tubulin dimers. The N-terminal domain has no effect on microtubule polymerization. Endogenous HsSAS-6 co-precipitates with microtubules from S-phase HeLa cell lysates. |
In vitro tubulin polymerization assay, microtubule pulldown, co-immunoprecipitation from cell lysate, isothermal calorimetry, size-exclusion chromatography |
Biochemistry |
Medium |
26422590
|
| 2015 |
In vitro, both Drosophila Sas-6 N-terminal domain homo-oligomerization and Ana2 CCCD tetramerization are required for efficient centriole assembly in vivo. Point mutations that perturb Sas-6 homo-oligomerization in vitro strongly impair centriole assembly in Drosophila. The Ana2 CCCD forms a tetramer with an unusual parallel-coil topology (structure solved to 0.8 Å), and the Sas-6 N-terminal domain forms higher-order oligomers through canonical interactions (structure at 2.9 Å). |
X-ray crystallography (0.8 Å and 2.9 Å), in vitro oligomerization assays, in vivo Drosophila genetics with point mutants |
eLife |
High |
26002084
|
| 2015 |
De novo centriole formation in human cells can occur in the absence of SAS-6 self-oligomerization, demonstrating that centriole biogenesis does not strictly depend on SAS-6 self-assembly. Canonically duplicated centrioles always form correctly, whereas de novo centrioles are prone to structural errors even when SAS-6 self-oligomerization is intact. |
Reconstitution of de novo centriole synthesis in human cells, SAS-6 oligomerization-deficient mutants, electron microscopy |
eLife |
Medium |
26609813
|
| 2016 |
Engineering Chlamydomonas SAS-6 to form oligomers with symmetries ranging from five- to ten-fold showed that SAS-6 self-assembly properties instruct cartwheel symmetry. A SAS-6 mutant forming six-fold symmetric cartwheels in vitro produced eight- or nine-fold cartwheels in vivo, and with Bld10 mutants weakening cartwheel-microtubule interactions, produced six- to eight-fold cartwheels. The microtubule wall maintained eight- and nine-fold symmetries, indicating cartwheel and microtubule wall assemble interdependently. Human cells expressing analogous SAS-6 mutations formed nine-fold centrioles with impaired length and organization. |
In vitro oligomerization assays, Chlamydomonas and human cell expression of engineered SAS-6 mutants, electron microscopy |
Nature cell biology |
High |
26999736
|
| 2017 |
Drosophila Plk4 first phosphorylates a single serine (S38) in the conserved ANST motif of Ana2 to promote Ana2 recruitment to the centriole, and then phosphorylates four serines in the STAN motif to enable Ana2 to recruit Sas6. Non-phosphorylatable S38A Ana2 fails to load onto the procentriole and blocks centriole duplication, establishing a sequential two-step phosphorylation mechanism for Sas6 recruitment. |
In vitro kinase assay, mass spectrometry, Drosophila genetics with phospho-mutant rescue, live imaging |
Open biology |
High |
29263250
|
| 2017 |
The DNA replication licensing factor Cdc6 is recruited to the proximal side of centrioles via cyclin A and negatively regulates centrosome duplication by binding Sas-6 and inhibiting its interaction with STIL. Plk4 phosphorylates Cdc6, disrupting the Sas-6–Cdc6 interaction and thereby counteracting the inhibitory effect of Cdc6 on Sas-6. Overexpression of wild-type Cdc6 or a Plk4-unphosphorylatable Cdc6 mutant reduces centrosome over-duplication. |
Co-immunoprecipitation, co-localization, siRNA knockdown, overexpression with functional centrosome duplication readout |
Nature communications |
Medium |
28447620
|
| 2018 |
High-speed atomic force microscopy (photothermal off-resonance tapping) reveals the kinetics of SAS-6 ring formation and demonstrates that distinct biogenesis routes can be followed to assemble a nine-fold symmetrical ring structure, showing the assembly reaction is driven by weak interactions on a surface. |
High-speed atomic force microscopy (PORT), kinetic analysis of self-assembly |
Nature nanotechnology |
Medium |
29784964
|
| 2019 |
The conserved PCM component Pcp1/pericentrin directly interacts with and recruits SAS-6. This interaction is conserved and important for centriole assembly, particularly centriole elongation. Calmodulin-binding region of Pcp1/pericentrin is critical for SAS-6 interaction. |
Ectopic expression in fission yeast, co-immunoprecipitation, genetic assays in animal cells |
eLife |
Medium |
31182187
|
| 2020 |
Human SAS-6 C-terminus is required for centriolar microtubule formation by interacting with the γ-tubulin ring complex (γ-TuRC). Deletion of HsSAS-6 C-terminus disrupts microtubule formation in daughter centrioles, resulting in cells with only two centrioles at a single site. SAS-6 associates with γ-TuRC proteins at the centrosome, and high-resolution microscopy reveals γ-tubulin as multiple lobes surrounding the HsSAS-6-containing central hub. |
Co-immunoprecipitation, deletion mutant analysis, siRNA knockdown, high-resolution fluorescence microscopy |
Current biology : CB |
Medium |
32442461
|
| 2020 |
Interaction surfaces between Drosophila Ana2 and Sas6 lie in the C-terminal parts of both proteins, as identified by hydrogen-deuterium exchange coupled with mass spectrometry (HDX-MS) and confirmed by mutagenesis. The Sas6 site required for Ana2 binding is distinct from the site required for Gorab binding, and Sas6 can simultaneously bind both Ana2 and Gorab. |
HDX-MS, in vitro complex formation, mutagenesis, co-immunoprecipitation |
Open biology |
Medium |
33171067
|
| 2021 |
Monomeric Drosophila Gorab binds Sas6 via an antiparallel interaction between a segment of Gorab's coiled-coil and the parallel coiled-coil dimer of Sas6, forming a stable heterotrimer visible by EM. Mutation of a single leucine in Sas6's Gorab-binding domain reduces affinity 16-fold and abolishes centriole duplication, demonstrating this interaction is essential. Gorab dimers at the Golgi exist in equilibrium with Sas6-associated Gorab monomers at the centriole. |
HDX-MS, electron microscopy, mutagenesis with in vivo centriole duplication assay, biochemical binding assays |
eLife |
High |
33704067
|
| 2021 |
Monobodies against Chlamydomonas SAS-6 characterized by X-ray crystallography, AFM, and cryo-EM reveal distinct interaction modes that specifically impair ring assembly or ring stacking. Monobody MBCRS6-15 induces a conformational change converting CrSAS-6 from ring to helix conformation, and this alteration impairs centriole biogenesis in human cells. |
X-ray crystallography, atomic force microscopy, cryo-EM, human cell centriole biogenesis assay |
Nature communications |
High |
34155202
|
| 2022 |
Crystallographic structures of the Chlamydomonas reinhardtii SAS-6 coiled-coil domain reveal an asymmetric homo-oligomerization interaction. Using cryo-EM reconstitution, amino acid substitutions disrupting this asymmetric association impair SAS-6 ring stacking, suggesting the coiled-coil asymmetric interaction provides polarity to the cartwheel and may assist establishment of the centriolar proximal-distal axis. |
X-ray crystallography, cryo-EM reconstitution assay, site-directed mutagenesis |
Structure (London, England : 1993) |
High |
35240058
|
| 2022 |
In C. elegans, the chromatin remodeling protein CHD-1 and the transcription factor EFL-1/DPL-1 cooperate to downregulate CDK-2, which in turn controls SAS-6 protein levels. Loss of CHD-1 increases SAS-6 levels and produces extra centrioles, revealing a transcriptional/post-translational axis for controlling centriole number via SAS-6 abundance. |
C. elegans genetics (epistasis), RNAi, Western blot for protein levels, centriole counting |
PLoS genetics |
Medium |
35377871
|
| 2024 |
In mouse embryos, Sass6 (SASS6) is required for centriole formation, and Sass6-mutant embryos lack centrioles, activate the mitotic surveillance cell death pathway, and arrest at mid-gestation. In mouse embryonic stem cells (mESCs), SAS-6 is not required for de novo centriole formation but is essential to maintain centriole architecture. High PLK4 activity and elevated centrosomal protein levels in mESCs enable SAS-6-independent centriole biogenesis. |
Mouse knockout genetics, immunofluorescence, centriole ultrastructure analysis, cell death pathway assays |
eLife |
High |
38407237
|
| 2025 |
SAS-6 undergoes phase separation in vitro and forms droplets when overexpressed in cells. CDK-1 directly phosphorylates SAS-6 at its C-terminus (identified by mass spectrometry and kinase assays), which inhibits SAS-6 phase separation and weakens interactions between centriolar proteins. Phospho-mimetic and phospho-deficient mutants demonstrate that dynamic SAS-6 phosphorylation is essential for centrosome assembly during early meiotic prophase and for centrosome elimination during late meiotic prophase (oogenesis) in C. elegans. |
In vitro phase separation assay, mass spectrometry, in vitro kinase assay, C. elegans genetics with phospho-mutants, live imaging |
EMBO reports |
Medium |
40410380
|
| 2025 |
FBXW7 E3 ubiquitin ligase mediates degradation of the STIL-SAS6 cartwheel assembly complex. Plk4 kinase activity is required for FBXW7-mediated STIL-SAS6 degradation. The same Plk4-phosphorylated sites in STIL that promote STIL-SAS6 interaction for centriole assembly also stabilize FBXW7 binding to STIL, creating a dual mechanism: phosphorylation promotes assembly and then triggers destruction to prevent centriole overduplication. Depletion of FBXW7 induces premature centriole duplication through excessive STIL-SAS6 stabilization. |
Co-immunoprecipitation, siRNA knockdown, overexpression with centriole counting, ubiquitination assay, Plk4 inhibitor treatment |
The Journal of biological chemistry |
Medium |
41453690
|
| 2025 |
Non-degradable SAS-6 (SAS-6ND, escaping APCCdh1-targeted degradation) increases ciliation and cell invasion and upregulates the YAP/TAZ pathway. SAS-6-mediated invasion is prevented by YAP downregulation or by blocking ciliogenesis, placing SAS-6 upstream of YAP/TAZ-dependent transcription in the invasion pathway. SAS-6 levels are subject to APCCdh1-targeted degradation at the end of mitosis and G1. |
Non-degradable SAS-6 mutant expression, siRNA knockdown, invasion assays, YAP nuclear translocation imaging, TEAD reporter assay |
Life science alliance |
Medium |
40825584
|