ZWINT

ZWINT (Zwint-1/SIP30) is a dual-function protein acting both as a structural and signaling hub at the mitotic kinetochore and as a regulator of presynaptic vesicle exocytosis in neurons (PMID:16732327, PMID:12068081). At the outer kinetochore, ZWINT is a component of the Mis12 core complex and is recruited downstream of HEC1/NDC80, with which it directly interacts; it in turn is required and sufficient for kinetochore localization of ZW10, defining a sequential HEC1→ZWINT→ZW10 recruitment pathway essential for spindle assembly checkpoint signaling and faithful chromosome segregation (PMID:15502821, PMID:15485811, PMID:16732327). Aurora B phosphorylates ZWINT at three sites, and this modification is required for assembly of the ROD-ZW10-Zwilch (RZZ) complex at kinetochores and for poleward streaming that silences the checkpoint, integrating ZWINT into both checkpoint activation and silencing (PMID:21775627). ZWINT function extends to oocyte meiosis I, where it is required for kinetochore recruitment of Mad2 and for Aurora C-mediated correction of erroneous attachments (PMID:26486467). ZWINT abundance is controlled by ubiquitin-proteasomal degradation through APC/C-Cdc20 acting on a D-box motif during mitotic exit and through the E3 ligase TRIM17/Terf (PMID:22023800, PMID:31945194). In neurons, ZWINT/SIP30 directly binds SNAP25 (with syntaxin co-precipitating indirectly) and binds the Rab GTPase Rab3c at an overlapping region, and it is required for the pool of releasable synaptic vesicles and the rate of vesicle exocytosis (PMID:18625232, PMID:12068081, PMID:38188363). In rat models of neuropathic pain, SIP30 is upregulated in the spinal cord and rostral anterior cingulate cortex through ERK/PKA-CREB signaling, where it modulates presynaptic glutamate release and contributes to pain-related affective behavior (PMID:19723624, PMID:24403136). ZWINT also promotes p53 ubiquitination and degradation to drive proliferation in pancreatic cancer, where it is transcriptionally induced by HIF1α under hypoxia (PMID:34900978).

1. 2004 High

   Established ZWINT as an outer-kinetochore component of the Mis12 core complex and defined its position relative to HEC1, answering where in kinetochore architecture it sits.

   Evidence Co-IP, RNAi, and immunofluorescence in HeLa cells; HP1-dependent Mis12 anchoring

   PMID:15502821

   Open questions at the time

   • Direct binding interface with Mis12 components not mapped
   • Functional consequence of HP1-Mis12 anchoring on ZWINT not dissected
2. 2004 High

   Defined ZWINT as required and sufficient for ZW10 kinetochore recruitment and as a spindle checkpoint component, linking it to chromosome segregation fidelity.

   Evidence siRNA depletion with multiple phenotypic readouts and domain-mapped Co-IP to the ZW10 N-terminus in HeLa cells

   PMID:15485811

   Open questions at the time

   • Structural basis of the ZWINT-ZW10 interaction not solved
   • Why CENP-F and dynamitin but not BUB1 depend on ZWINT not explained
3. 2004 Low

   Connected ZWINT loss to a Roberts-syndrome-like cytogenetic phenotype, reinforcing its role in chromosome segregation.

   Evidence Antisense oligonucleotide inhibition with CGH, spectral karyotyping, and atomic force microscopy

   PMID:15094189

   Open questions at the time

   • No direct molecular mechanism established beyond cytogenetic phenotype
   • Causal genetic link to Roberts syndrome not demonstrated
4. 2006 High

   Resolved the temporal order of kinetochore assembly, showing HEC1 directly recruits ZWINT, which then recruits ZW10 sequentially through mitosis.

   Evidence M-phase Co-IP, siRNA epistasis, and co-localization time-course in mitotic cells

   PMID:16732327

   Open questions at the time

   • Direct HEC1-ZWINT binding interface not mapped at residue level
   • Regulation of the recruitment timing not defined
5. 2011 High

   Identified Aurora B phosphorylation of ZWINT as the switch controlling RZZ assembly and, in phosphomimetic form, checkpoint silencing — placing ZWINT under kinase regulation in both SAC activation and silencing.

   Evidence In vitro kinase assay with MS phosphosite mapping and gain/loss-of-function phospho-mutants

   PMID:21775627

   Open questions at the time

   • How phosphorylation structurally enables RZZ docking unknown
   • Phosphatase reversing these sites not identified
6. 2011 Medium

   Showed TRIM17/Terf controls ZWINT abundance and that ZWINT levels influence proliferation, introducing post-translational control of ZWINT.

   Evidence Yeast two-hybrid, Co-IP, western blot degradation, and proliferation assays in MCF7 cells

   PMID:22023800

   Open questions at the time

   • Ubiquitination of ZWINT by TRIM17 not directly demonstrated
   • Cell-cycle timing of this degradation not defined
7. 2015 Medium

   Extended ZWINT's checkpoint role to female meiosis, showing it is required for Mad2 recruitment and Aurora C-mediated attachment correction to prevent aneuploidy.

   Evidence siRNA in mouse oocytes with Mad2 localization, aneuploidy scoring, and Aurora C inhibitor washout

   PMID:26486467

   Open questions at the time

   • Single-lab finding
   • Direct ZWINT-Mad2 or ZWINT-Aurora C interaction not shown
8. 2020 Medium

   Defined APC/C-Cdc20 D-box-dependent ubiquitination as the mechanism degrading ZWINT at mitotic exit, explaining how its kinetochore pool is cleared.

   Evidence In vivo ubiquitination, Co-IP, CHX chase, MG132 rescue, and D-box deletion in HEK293T/HeLa cells

   PMID:31945194

   Open questions at the time

   • Relationship between APC/C and TRIM17 routes of degradation unclear
   • Single-lab finding
9. 2002 Medium

   Identified ZWINT/SIP30 as a direct SNAP25-binding protein enriched in brain, opening a synaptic function distinct from its mitotic role.

   Evidence GST pull-down and Co-IP from brain tissue

   PMID:12068081

   Open questions at the time

   • Functional consequence of SNAP25 binding not tested here
   • Single-lab finding
10. 2008 Medium

    Showed ZWINT/SIP30 binds Rab3c at the same region used by SNAP25 in hippocampal neurons, situating it within presynaptic vesicle machinery.

    Evidence Yeast two-hybrid, Co-IP, neuronal co-localization, and SNAP25 domain competition

    PMID:18625232

    Open questions at the time

    • Whether SNAP25 and Rab3c binding are mutually exclusive in vivo unresolved
    • Single-lab finding
11. 2009 Medium

    Linked SIP30 to neuropathic pain via ERK/CREB-driven transcriptional upregulation in spinal cord and a functional requirement for the synaptic vesicle pool.

    Evidence CCI rat model with MEK inhibitor, sip30 promoter analysis, CREB ChIP, and PC12 siRNA vesicle assays

    PMID:19723624 PMID:19748740

    Open questions at the time

    • Direct neurotransmitter released by SIP30-dependent vesicles in spinal cord not identified
    • Single-lab findings
12. 2014 High

    Localized SIP30's pain contribution to the rACC and tied it to presynaptic glutamate release downstream of PKA/ERK, connecting molecular function to pain affect.

    Evidence In vivo rACC shRNA, PKA/ERK inhibitor pharmacology, mEPSC/paired-pulse electrophysiology, and glutamate measurement in CCI rats

    PMID:24403136

    Open questions at the time

    • Direct molecular target of SIP30 mediating glutamate release in rACC not defined
    • Link to its SNAP25/Rab3c partners in this context not tested
13. 2014 Low

    Reported peripherin isoforms as ZWINT/SIP30 partners that redistribute SIP30 and SNAP25 in motor neurons, hinting at cytoskeletal regulation of vesicle trafficking.

    Evidence Yeast two-hybrid, co-localization in SW13vim(-) cells, and immunofluorescence in primary motor neurons

    PMID:25113441

    Open questions at the time

    • Limited functional mechanistic data; awaits functional validation
    • Single-lab finding
14. 2021 Medium

    Identified a ZWINT-p53 axis in pancreatic cancer, with ZWINT promoting p53 degradation and being induced by HIF1alpha, linking it to oncogenic proliferation.

    Evidence Co-IP, ubiquitination and p53 luciferase reporter assays, HIF1alpha ChIP, and proliferation assays

    PMID:34900978

    Open questions at the time

    • Whether ZWINT acts as or recruits the E3 ligase for p53 not resolved
    • Single-lab finding
15. 2023 Medium

    Confirmed SIP30's specific requirement for the releasable vesicle pool and exocytosis rate without affecting endocytosis or recycling.

    Evidence siRNA in PC12 cells with FM1-43 fluorescence vesicle assay

    PMID:38188363

    Open questions at the time

    • Molecular step in exocytosis controlled by SIP30 not pinpointed
    • Single method, single lab

• How a single protein partitions between kinetochore checkpoint signaling and presynaptic exocytosis, and whether common partners or regulatory logic connect these roles, remains unresolved.
• No structural model reconciling kinetochore and synaptic interactions
• Tissue/cell-type determinants of which function dominates not defined
• Whether degradation routes (APC/C, TRIM17) operate in neurons unknown