ZSWIM8 encodes the substrate-recognition component of a Cullin-RING E3 ubiquitin ligase complex that recognizes Argonaute-miRNA complexes engaged with highly complementary target RNAs and promotes target-directed miRNA degradation. Human and metazoan evidence supports a CUL3/RBX1/ELOB/ELOC/ZSWIM8 complex, ubiquitin-proteasome-dependent AGO turnover, and an additional protein quality-control role toward intrinsically disordered substrates such as DAB1.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0031462 Cul2-RING ubiquitin ligase complex | IBA GO_REF:0000033 | MODIFY | Summary: Directionally correct as a Cullin-RING ligase annotation, but current human experimental evidence supports ZSWIM8 as part of a CUL3-containing CRL rather than a CUL2-RING ligase complex. Reason: The ZSWIM8-ELOB-ELOC adaptor module was tested against CUL2, CUL5, and CUL3 in the TDMD screen follow-up; CUL3, not CUL2, was required. The existing IDA annotation to Cul3-RING ubiquitin ligase complex is the appropriate replacement for the human protein. Proposed replacements: Cul3-RING ubiquitin ligase complex Supporting Evidence: PMID:33184234 In contrast, CUL3 knockout strongly repressed the reporter, suggesting that the ZSWIM8 E3 ligase represents a CRL in which ZSWIM8-ELOB-ELOC serve as substrate adapters for CUL3. |
| GO:0005829 cytosol | IEA GO_REF:0000044 | ACCEPT | Summary: Cytosolic localization is consistent with UniProt and with ZSWIM8 acting on AGO-miRNA complexes and cytosolic protein quality-control substrates. Reason: Although localization is not itself the catalytic function, cytosol is a supported site for ZSWIM8 activity and is appropriate to retain. Supporting Evidence: file:human/ZSWIM8/ZSWIM8-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm, cytosol |
| GO:0008270 zinc ion binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: ZSWIM8 contains a SWIM zinc-finger domain, so the IEA zinc-ion-binding annotation is plausible as a domain-level molecular feature. Reason: The zinc-finger feature supports retention, but the biologically informative core function is substrate-adaptor activity in a CRL rather than generic zinc binding. Supporting Evidence: file:human/ZSWIM8/ZSWIM8-uniprot.txt Znf_SWIM. (IPR007527) |
| GO:0016567 protein ubiquitination | IEA GO_REF:0000041 | ACCEPT | Summary: Protein ubiquitination is supported by UniProt pathway annotation and by experimental studies showing ZSWIM8 functions as the substrate adaptor of a Cullin-RING E3 ubiquitin ligase. Reason: ZSWIM8 is not the catalytic RING subunit, but as the substrate-recognition component of the CRL it directly enables ubiquitination of recruited substrates. Supporting Evidence: PMID:33184234 We identified a cullin-RING ubiquitin ligase (CRL), containing the substrate adaptor ZSWIM8, that mediates TDMD. |
| GO:0006515 protein quality control for misfolded or incompletely synthesized proteins | IDA PMID:35989311 The ZSWIM8 ubiquitin ligase regulates neurodevelopment by gu... | ACCEPT | Summary: ZSWIM8-dependent protein quality control is supported by knockout and mechanistic work showing ZSWIM8 controls DAB1 quality in neurodevelopment. Reason: The annotation captures a direct substrate-quality-control role for the ZSWIM8 ligase, distinct from but mechanistically related to its TDMD role. Supporting Evidence: PMID:35989311 Mechanistic studies reveal that ZSWIM8 controls protein quality of Disabled 1 (Dab1), a key signal molecule for brain development, thus protecting the signaling strength of Dab1. |
| GO:0140958 target-directed miRNA degradation | IMP PMID:33184237 The ZSWIM8 ubiquitin ligase mediates target-directed microRN... | ACCEPT | Summary: This is a core ZSWIM8 biological process: loss-of-function studies show that the ZSWIM8 CRL is required for target-directed miRNA degradation. Reason: The annotation is specific, experimentally supported, and captures the best-characterized conserved process mediated by ZSWIM8. Supporting Evidence: PMID:33184237 We found that this target-directed miRNA degradation (TDMD) required the ZSWIM8 Cullin-RING E3 ubiquitin ligase. file:human/ZSWIM8/ZSWIM8-deep-research-falcon.md ZSWIM8 is best-supported as the substrate-recognition subunit of a Cullin-RING ubiquitin ligase (CRL) complex that executes TDMD by targeting Argonaute proteins. |
| GO:0005829 cytosol | ISS GO_REF:0000024 | ACCEPT | Summary: The sequence-similarity transfer to cytosol is consistent with UniProt and with the cytosolic AGO-miRNA and protein quality-control contexts of ZSWIM8. Reason: This duplicates the IEA localization evidence but is not contradicted by experimental or curated summaries. Supporting Evidence: file:human/ZSWIM8/ZSWIM8-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm, cytosol |
| GO:0016567 protein ubiquitination | IDA PMID:33184234 A ubiquitin ligase mediates target-directed microRNA decay i... | ACCEPT | Summary: Directly supported by the TDMD study identifying ZSWIM8 as the substrate adaptor in a Cullin-RING ubiquitin ligase that acts on AGO-miRNA complexes. Reason: ZSWIM8 recruits substrates to the ubiquitination machinery, making this process annotation appropriate even though the catalytic RING activity is supplied by the CRL complex. Supporting Evidence: PMID:33184234 The ZSWIM8 CRL interacts with AGO proteins, promotes TDMD in a tailing and trimming-independent manner, and regulates miRNA expression in multiple cell types. |
| GO:0031463 Cul3-RING ubiquitin ligase complex | IDA PMID:33184234 A ubiquitin ligase mediates target-directed microRNA decay i... | ACCEPT | Summary: The Cul3-RING ubiquitin ligase complex annotation is the experimentally supported complex context for human ZSWIM8. Reason: CUL3 was required in the CRISPR screen validation, while CUL2 and CUL5 knockouts were not, supporting CUL3 as the relevant cullin scaffold. Supporting Evidence: PMID:33184234 In contrast, CUL3 knockout strongly repressed the reporter, suggesting that the ZSWIM8 E3 ligase represents a CRL in which ZSWIM8-ELOB-ELOC serve as substrate adapters for CUL3. |
| GO:0043161 proteasome-mediated ubiquitin-dependent protein catabolic process | IDA PMID:33184234 A ubiquitin ligase mediates target-directed microRNA decay i... | ACCEPT | Summary: ZSWIM8-mediated TDMD proceeds through ubiquitin-proteasome-dependent turnover of AGO-containing complexes, so this process annotation is supported. Reason: The annotation is broader than target-directed miRNA degradation but accurately captures the proteasome-dependent degradation step mediated by the ZSWIM8 CRL. Supporting Evidence: PMID:33184234 These findings suggest a model in which the ZSWIM8 ubiquitin ligase mediates TDMD by directing proteasomal decay of miRNA-containing complexes engaged with highly complementary targets. |
| GO:1990756 ubiquitin-like ligase-substrate adaptor activity | IDA PMID:33184234 A ubiquitin ligase mediates target-directed microRNA decay i... | ACCEPT | Summary: This molecular-function term captures ZSWIM8's core role as the substrate-recognition component of the TDMD Cullin-RING ubiquitin ligase. Reason: ZSWIM8 binds AGO proteins engaged with TDMD targets and recruits them to the CUL3 CRL, which is exactly substrate-adaptor activity. Supporting Evidence: PMID:33184234 We identified a cullin-RING ubiquitin ligase (CRL), containing the substrate adaptor ZSWIM8, that mediates TDMD. |
| GO:1990756 ubiquitin-like ligase-substrate adaptor activity | IDA PMID:33184237 The ZSWIM8 ubiquitin ligase mediates target-directed microRN... | ACCEPT | Summary: Independent TDMD work also supports ZSWIM8 as the Cullin-RING ligase adaptor required for target-directed miRNA degradation. Reason: The annotation is a core molecular function and is supported by loss-of-function evidence linking the ZSWIM8 CRL to AGO proteolysis and miRNA degradation. Supporting Evidence: PMID:33184237 This and other findings support a mechanistic model of TDMD in which target-directed proteolysis of AGO by the ubiquitin-proteasome pathway exposes the miRNA for degradation. PMID:33184234 We identified a cullin-RING ubiquitin ligase (CRL), containing the substrate adaptor ZSWIM8, that mediates TDMD. |
| GO:2000627 positive regulation of miRNA catabolic process | IDA PMID:33184234 A ubiquitin ligase mediates target-directed microRNA decay i... | MODIFY | Summary: ZSWIM8 positively regulates miRNA catabolism by mediating TDMD of miRNAs engaged with highly complementary target RNAs. Reason: The term is directionally correct but less specific than the current GO term for the experimentally demonstrated process, target-directed miRNA degradation. Proposed replacements: target-directed miRNA degradation Supporting Evidence: PMID:33184234 The requirement for the ZSWIM8 ubquitin ligase in TDMD induced by two unrelated substrates in different cell lines suggests that it functions broadly in this pathway. |
| GO:2000627 positive regulation of miRNA catabolic process | IDA PMID:33184237 The ZSWIM8 ubiquitin ligase mediates target-directed microRN... | MODIFY | Summary: The Bartel study supports the same positive regulatory role for ZSWIM8 in miRNA catabolism through the TDMD pathway. Reason: The annotation should be replaced by the more specific TDMD process term, which captures the tested biology without relying on a broad parent-like regulation term. Proposed replacements: target-directed miRNA degradation Supporting Evidence: PMID:33184237 loss-of-function studies indicated that the ZSWIM8 Cullin-RING ligase accelerates degradation of numerous miRNAs in cells of mammals, flies, and nematodes |
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Download this section (compressed HTML)Q: Which endogenous human TDMD targets account for the strongest ZSWIM8-dependent miRNA half-life changes across cell types?
Q: Does ZSWIM8 use the same substrate-recognition surface for AGO-miRNA complexes and intrinsically disordered protein quality-control substrates such as DAB1?
Q: Is the Cul2-RING IBA annotation a legacy transfer from non-human EBAX systems that should be corrected upstream to Cul3-RING ubiquitin ligase complex?
Experiment: Endogenous-tag ZSWIM8, CUL3, ELOB, and ELOC in human cells and perform target-triggered AGO proximity labeling with and without TDMD-inducing transcripts.
Hypothesis: ZSWIM8 recruits AGO-miRNA complexes to a CUL3 CRL specifically when TDMD target pairing exposes the AGO-bound miRNA.
Type: proteomics/proximity labeling
Experiment: Mutational separation of ZSWIM8 SWIM/TPR/C-terminal regions followed by rescue assays for miR-7 TDMD and DAB1 protein quality control.
Hypothesis: Distinct substrate-recognition modules contribute to AGO-dependent TDMD and DAB1 quality-control functions.
Type: structure-function rescue
Experiment: Comparative CRL assembly assays testing CUL2, CUL3, and CUL5 binding to human ZSWIM8-ELOB-ELOC under endogenous expression conditions.
Hypothesis: Human ZSWIM8 preferentially forms a functional CUL3-RING ubiquitin ligase complex rather than a Cul2-RING complex.
Type: biochemical reconstitution/co-immunoprecipitation
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