Affinage

SSX2IP

Afadin- and alpha-actinin-binding protein · UniProt Q9Y2D8

Length
614 aa
Mass
71.2 kDa
Annotated
2026-04-28
13 papers in source corpus 9 papers cited in narrative 10 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

SSX2IP is a centriolar satellite-associated protein that functions as a critical organizer of centrosome integrity, microtubule anchoring, and ciliogenesis. It is delivered to the centrosome in a satellite-dependent manner, where it binds the γ-tubulin ring complex (γ-TuRC) and forms a conserved complex with Wdr8 to promote γ-TuRC loading, microtubule nucleation and anchoring, and proper centriole assembly and duplication (PMID:23816619, PMID:24397932, PMID:25833712, PMID:26545777). At the basal body, SSX2IP recruits Cep290 to centriolar satellites and is required for BBSome entry into cilia, Rab8 accumulation, and ciliary membrane protein targeting, with loss of its zebrafish orthologue disrupting left–right asymmetry (PMID:24356449, PMID:24397932). Beyond centrosome biology, SSX2IP interacts with the LIM-domain adaptor Wtip to participate in cell-junction remodeling during neural tube closure and, in cancer contexts, promotes cisplatin resistance by enhancing extracellular vesicle–mediated drug export and regulates FANCI to drive proliferation (PMID:34710136, PMID:41827805, PMID:39533770).

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 2002 Medium

    The initial molecular identity of SSX2IP was established as a nuclear binding partner of the cancer/testis antigen SSX2, providing the first evidence that SSX2IP participates in protein–protein interactions relevant to cancer biology.

    Evidence Yeast two-hybrid screen followed by GST pull-down and colocalization in transfected cells

    PMID:12007189

    Open questions at the time
    • No endogenous interaction validated; relies on overexpression and in vitro binding
    • Functional consequence of SSX2–SSX2IP interaction unknown
    • Native subcellular localization of endogenous SSX2IP uncharacterized
  2. 2013 High

    A pivotal mechanistic advance showed that SSX2IP is a centrosome-associated protein required for γ-TuRC loading, microtubule nucleation, and spindle assembly, repositioning it from an obscure SSX2 interactor to a core centrosome maturation factor.

    Evidence Immunodepletion and rescue in Xenopus egg extracts, quantitative proteomics identifying γ-TuRC and PCM-1 interactions, knockdown in medaka causing PCM fragmentation and chromosome segregation errors

    PMID:23816619

    Open questions at the time
    • Structural basis of SSX2IP–γ-TuRC interaction unknown
    • Whether SSX2IP directly contacts γ-tubulin or a γ-TuRC subunit not resolved
  3. 2013 High

    SSX2IP was placed in the ciliogenesis pathway upstream of Cep290, the BBSome, and Rab8, revealing that its satellite-localized function extends beyond mitotic centrosomes to primary cilium formation.

    Evidence siRNA knockdown in human cells with immunofluorescence showing reduced Cep290 recruitment, impaired BBSome ciliary entry, diminished Rab8 and somatostatin receptor 3 targeting

    PMID:24356449

    Open questions at the time
    • Direct biochemical interaction between SSX2IP and Cep290 not demonstrated
    • Whether SSX2IP acts on Cep290 via satellite integrity or via a specific binding interface is unresolved
  4. 2014 High

    The mechanism of SSX2IP centrosomal recruitment was clarified as centriolar satellite-dependent, and its function was extended to microtubule anchoring at the centrosome, with in vivo validation showing that loss of the zebrafish orthologue causes ciliary defects and laterality abnormalities.

    Evidence siRNA knockdown and microtubule anchoring assays in human cells, zebrafish morpholino knockdown, Co-IP with γ-tubulin complex

    PMID:24397932

    Open questions at the time
    • The satellite component(s) directly responsible for SSX2IP transport not identified
    • Whether microtubule anchoring defect is separable from γ-TuRC loading defect not tested
  5. 2015 High

    Two studies resolved how SSX2IP integrates into centrosome biogenesis: it is essential for proper centriole structure and duplication, with its depletion trapping satellites at minus ends and producing EM-verified centriolar defects, and it forms a conserved complex with Wdr8 that is required for its mitotic centrosome recruitment.

    Evidence Superresolution and electron microscopy of centrioles after knockdown, Plk4 epistasis, mass spectrometry identification of the SSX2IP–Wdr8 complex, reciprocal knockdown phenocopy

    PMID:25833712 PMID:26545777

    Open questions at the time
    • Stoichiometry and structure of the SSX2IP–Wdr8 complex unknown
    • How SSX2IP depletion simultaneously blocks Plk4-driven centriole overduplication yet accelerates reduplication during S-phase arrest is mechanistically unresolved
    • Whether Wdr8 also participates in ciliary functions of SSX2IP not tested
  6. 2021 Medium

    A non-centrosomal role for SSX2IP was established through its physical interaction with the LIM-domain adaptor Wtip and functional cooperation during Xenopus neural tube closure, linking SSX2IP to cell-junction remodeling in morphogenesis.

    Evidence Targeted proximity biotinylation plus Co-IP in cultured cells, double morpholino knockdown in Xenopus embryos

    PMID:34710136

    Open questions at the time
    • Whether the SSX2IP–Wtip interaction involves the centrosomal or a distinct cytoplasmic pool is unclear
    • Downstream junction-remodeling target(s) not identified
    • Not independently confirmed by a second group
  7. 2024 Medium

    SSX2IP was linked to cancer cell proliferation and migration through a physical interaction with FANCI, establishing SSX2IP as an upstream positive regulator of FANCI expression in breast cancer cells.

    Evidence Co-immunoprecipitation, siRNA knockdown with FANCI rescue overexpression in breast cancer cell proliferation and migration assays

    PMID:39533770

    Open questions at the time
    • Single Co-IP without reciprocal validation or domain mapping
    • Mechanism by which SSX2IP regulates FANCI expression (transcriptional vs. post-translational) unknown
    • Relevance of this axis in non-cancer cells untested
  8. 2026 Medium

    SSX2IP was identified as a mediator of cisplatin resistance in ovarian cancer by promoting extracellular vesicle–mediated cisplatin export, validated as a direct miR-625-3p target whose upregulation overrides microRNA-mediated drug sensitization.

    Evidence Reporter assays, EV mass spectrometry, high-speed confocal microscopy, cell death ELISA, in vivo xenograft

    PMID:41827805

    Open questions at the time
    • Mechanism by which SSX2IP promotes EV-mediated cisplatin export not defined at the molecular level
    • Whether this EV function relates to SSX2IP's centrosomal or satellite biology is unknown
    • Not independently replicated

Open questions

Synthesis pass · forward-looking unresolved questions
  • Key unresolved questions include the structural basis of SSX2IP's interaction with γ-TuRC and Wdr8, how its centrosomal versus junction-remodeling functions are partitioned across different cellular pools, and whether its roles in cancer (FANCI regulation, EV-mediated drug export) reflect centrosome-dependent or centrosome-independent mechanisms.
  • No crystal or cryo-EM structure of SSX2IP or its complexes
  • Separation-of-function mutants distinguishing centrosomal from non-centrosomal roles have not been generated
  • In vivo mammalian knockout phenotype not reported

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0008092 cytoskeletal protein binding 3
Localization
GO:0005815 microtubule organizing center 5 GO:0005929 cilium 2 GO:0005634 nucleus 1
Pathway
R-HSA-1640170 Cell Cycle 3 R-HSA-1852241 Organelle biogenesis and maintenance 3
Partners
CEP290FANCIPCM1SSX2TUBG1WDR8WTIP
Complex memberships
SSX2IP–Wdr8 complexγ-TuRC (via interaction)

Evidence

Reading pass · 10 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2002 SSX2IP was identified as a direct binding partner of the cancer-related protein SSX2, interacting with the N-terminal moiety of SSX2, as demonstrated by yeast two-hybrid screening and GST pull-down assays. SSX2IP colocalizes with SSX2 in the nucleus of transfected cells. Yeast two-hybrid, GST pull-down, immunofluorescence of transfected cells Genes, chromosomes & cancer Medium 12007189
2013 SSX2IP accumulates at spindle poles in a Dynein-dependent manner in Xenopus egg extracts, interacts with the γ-tubulin ring complex (γ-TuRC) and the centriolar satellite protein PCM-1, and is required for γ-TuRC loading onto centrosomes. Immunodepletion of SSX2IP impedes γ-TuRC loading, reduces microtubule nucleation, and causes spindle assembly failure. Quantitative proteomics, immunodepletion in Xenopus egg extracts, Co-immunoprecipitation, microtubule nucleation assay The Journal of cell biology High 23816619
2013 SSX2IP knockdown in rapidly dividing medaka blastomeres and somatic cells caused fragmentation of pericentriolar material and chromosome segregation errors, establishing SSX2IP as a centrosome maturation and maintenance factor. siRNA/morpholino knockdown, live imaging, immunofluorescence in medaka embryos and somatic cells The Journal of cell biology High 23816619
2013 SSX2IP localizes to the basal body of primary cilia and is required for efficient recruitment of the ciliopathy-associated satellite protein Cep290 to centriolar satellites and the basal body. Loss of SSX2IP drastically reduces BBSome entry into cilia, impairs Rab8 accumulation, reduces axoneme length, and limits targeting of the ciliary membrane protein somatostatin receptor 3. siRNA knockdown in human cells, immunofluorescence, localization analysis Molecular biology of the cell High 24356449
2014 hMsd1/SSX2IP is delivered to the centrosome in a centriolar satellite-dependent manner, binds the γ-tubulin complex, and is required for microtubule anchoring at the centrosome. Its depletion leads to disorganized interphase microtubules, misoriented mitotic spindles with reduced length and intensity, and ciliogenesis defects. Zebrafish knockdown of the orthologue causes ciliary defects and disrupts left-right asymmetry. siRNA knockdown, microtubule anchoring assays, zebrafish morpholino knockdown, Co-immunoprecipitation with γ-tubulin complex EMBO reports High 24397932
2015 hMsd1/SSX2IP-mediated microtubule anchoring is essential for proper centriole assembly and duplication. Upon hMsd1/SSX2IP knockdown, centriolar satellites become stuck at the microtubule minus end near the centrosome, accumulate centrosomal proteins ectopically, centriole structures become faulty (shown by superresolution and electron microscopy), and cells are insensitive to Plk4 overproduction-induced ectopic centriole formation yet accelerate centrosome reduplication upon hydroxyurea arrest. siRNA knockdown, superresolution microscopy, electron microscopy, Plk4 overexpression epistasis, hydroxyurea arrest Molecular biology of the cell High 25833712
2015 SSX2IP forms a conserved complex with Wdr8 at the centrosome (identified by mass spectrometry). Wdr8 depletion reduces recruitment of hMsd1/SSX2IP to the mitotic centrosome, and knockdown of either Wdr8 or hMsd1/SSX2IP produces similar mitotic defects (shortened and misoriented spindle microtubules), placing Wdr8 upstream of SSX2IP at the centrosome. Mass spectrometry, Co-immunoprecipitation, siRNA knockdown, superresolution microscopy, spindle orientation assay Biochemical and biophysical research communications Medium 26545777
2021 SSX2IP physically associates with the N-terminal domain of Wtip (a LIM-domain adaptor) as identified by targeted proximity biotinylation and confirmed by Co-immunoprecipitation. Double depletion of Wtip and SSX2IP in Xenopus embryos disrupts neural tube closure, indicating functional interaction in cell junction remodeling during neurulation. Targeted proximity biotinylation (BirA-anti-GFP), Co-immunoprecipitation, Xenopus embryo double morpholino knockdown PloS one Medium 34710136
2024 SSX2IP physically interacts with FANCI (FA Complementation Group I) as demonstrated by Co-IP, and positively regulates FANCI expression. FANCI overexpression partially reverses the inhibitory effects of SSX2IP knockdown on breast cancer cell proliferation and migration, placing SSX2IP upstream of FANCI in this pathway. Co-immunoprecipitation, siRNA knockdown, rescue overexpression, functional proliferation/migration assays Cell biology international Medium 39533770
2026 SSX2IP mediates cisplatin resistance in ovarian cancer cells by promoting the export of cisplatin via extracellular vesicles (EVs). SSX2IP was confirmed as a direct target of miR-625-3p; its upregulation abrogates miR-625-3p-mediated cisplatin sensitization by enhancing EV-mediated cisplatin export. Reporter assays (target validation), mass spectrometry of EVs, high-speed confocal microscopy, cell death ELISA, in vivo xenograft Cancers Medium 41827805

Source papers

Stage 0 corpus · 13 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2013 Epigenetic silencing of miR-338-3p contributes to tumorigenicity in gastric cancer by targeting SSX2IP. PloS one 63 23826132
2013 The centriolar satellite protein SSX2IP promotes centrosome maturation. The Journal of cell biology 58 23816619
2013 The novel centriolar satellite protein SSX2IP targets Cep290 to the ciliary transition zone. Molecular biology of the cell 55 24356449
2002 The cancer-related protein SSX2 interacts with the human homologue of a Ras-like GTPase interactor, RAB3IP, and a novel nuclear protein, SSX2IP. Genes, chromosomes & cancer 54 12007189
2014 Msd1/SSX2IP-dependent microtubule anchorage ensures spindle orientation and primary cilia formation. EMBO reports 38 24397932
2015 Centriolar satellite- and hMsd1/SSX2IP-dependent microtubule anchoring is critical for centriole assembly. Molecular biology of the cell 26 25833712
2013 SSX2IP promotes metastasis and chemotherapeutic resistance of hepatocellular carcinoma. Journal of translational medicine 24 23452395
2015 The conserved Wdr8-hMsd1/SSX2IP complex localises to the centrosome and ensures proper spindle length and orientation. Biochemical and biophysical research communications 17 26545777
2007 SSX2IP: an emerging role in cancer. Biochemical and biophysical research communications 15 17904521
2021 Identification of the centrosomal maturation factor SSX2IP as a Wtip-binding partner by targeted proximity biotinylation. PloS one 12 34710136
2022 MiRNA-181b-5p Modulates Cell Proliferation, Cell Cycle, and Apoptosis by Targeting SSX2IP in Acute Lymphoblastic Leukemia. Turkish journal of haematology : official journal of Turkish Society of Haematology 9 35658330
2026 MicroRNA-625-3p Increases Chemosensitivity in Ovarian Cancer Cells Through Decreasing SSX2IP-Mediated Cisplatin Export in Extracellular Vesicles. Cancers 0 41827805
2024 SSX2IP promotes cell proliferation and migration in breast cancer by regulating FANCI. Cell biology international 0 39533770