id: Q9VKB2
gene_symbol: Ced-12
product_type: PROTEIN
status: DRAFT
taxon:
  id: NCBITaxon:7227
  label: Drosophila melanogaster
description: >
  Ced-12 (also known as ELMO/dELMO) is an evolutionarily conserved adaptor protein that partners with
  DOCK family GEFs (primarily Mbc/Myoblast city in Drosophila) to form a Rac-specific GEF module.
  The protein contains a PH domain, ARM-like repeats, and a proline-rich SH3-binding motif.
  Ced-12 enhances the guanyl-nucleotide exchange factor activity of its DOCK partners toward Rac GTPases,
  leading to localized Rac activation that drives WAVE/SCAR-mediated actin polymerization via Arp2/3.
  This signaling axis is critical for multiple actin-dependent cellular processes including myoblast fusion,
  border cell migration, thorax closure, CNS development, and muscle attachment site formation.
  While direct experimental evidence in Drosophila focuses on cell migration and fusion processes,
  the conserved role of ELMO/CED-12 proteins in apoptotic corpse engulfment (efferocytosis) is well-established
  across metazoa and is expected to be conserved in D. melanogaster based on orthology.
existing_annotations:
- term:
    id: GO:0005886
    label: plasma membrane
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >
      IBA annotation based on phylogenetic inference. ELMO proteins localize to the plasma membrane
      at sites of active Rac signaling, including phagocytic cups, leading edges during migration,
      and fusion foci during myoblast fusion.
    action: ACCEPT
    reason: >
      ELMO/CED-12 proteins function at the plasma membrane where they partner with DOCK-family GEFs
      to activate Rac signaling. The deep research confirms that DOCK-ELMO complexes localize to
      membrane-proximal sites including phagocytic cups and leading edges (Venkatachalam et al. 2024,
      PLOS Genetics). Plasma membrane localization is consistent with the PH domain-mediated membrane
      targeting of ELMO proteins (PMID:18163987, PMID:21283588). IBA is appropriate and well-supported.
    supported_by:
      - reference_id: PMID:18163987
        supporting_text: "we describe the isolation of Drosophila ELMO/CED-12, an approximately 82 kDa protein with a pleckstrin homology (PH) and proline-rich domain, by interaction with the MBC SH3 domain"
      - reference_id: file:DROME/Ced-12/Ced-12-deep-research-falcon.md
        supporting_text: "Ced-12-Mbc is predicted to localize to phagocytic cups and corpse contacts to drive Rac-dependent branched actin"

- term:
    id: GO:0007015
    label: actin filament organization
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >
      IBA annotation for actin filament organization. The DOCK-ELMO complex activates Rac, which in turn
      stimulates WAVE/SCAR-Arp2/3 mediated branched actin polymerization.
    action: ACCEPT
    reason: >
      This is a core function of Ced-12/ELMO proteins. The DOCK-ELMO-Rac signaling axis drives
      actin cytoskeletal reorganization through the WAVE/SCAR-Arp2/3 pathway. Experimental evidence
      from C. elegans (PMID:11703939) and structural/genetic studies in 2024 (Venkatachalam et al.,
      PLOS Genetics; Kukimoto-Niino et al., JBC) confirm this conserved function. IBA appropriately
      captures this phylogenetically conserved role.
    supported_by:
      - reference_id: PMID:11703939
        supporting_text: "Expression of CED-12 and its counterparts in murine Swiss 3T3 fibroblasts induced Rho GTPase-dependent formation of actin filament bundles"
      - reference_id: deep-research
        supporting_text: "Activated Rac stimulates the WAVE/SCAR complex, which activates Arp2/3 to build branched actin networks at membrane-proximal sites"

- term:
    id: GO:0048870
    label: cell motility
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >
      IBA annotation for cell motility. ELMO/CED-12 proteins are essential regulators of cell migration
      through their role in Rac activation at leading edges.
    action: ACCEPT
    reason: >
      Cell motility is a well-established function of ELMO/CED-12 proteins across species. In Drosophila,
      experimental evidence directly supports roles in border cell migration (PMID:17637670, PMID:18163987)
      and other migratory processes. The IBA annotation correctly captures this phylogenetically conserved function.
    supported_by:
      - reference_id: PMID:17637670
        supporting_text: "The myoblast city (Mbc, also known as DOCK180) and engulfment and cell motility (ELMO, also known as Ced-12) pathway is required for the early phase, in which guidance depends on subcellular localization of signalling within a leading cell"
      - reference_id: PMID:11703939
        supporting_text: "The C. elegans gene ced-12 functions in the engulfment of apoptotic cells and in cell migration"

- term:
    id: GO:0006909
    label: phagocytosis
  evidence_type: IEA
  original_reference_id: GO_REF:0000043
  review:
    summary: >
      IEA annotation from UniProtKB keyword mapping (Phagocytosis keyword). ELMO/CED-12 proteins are
      well-established regulators of phagocytosis, particularly engulfment of apoptotic cells (efferocytosis).
    action: ACCEPT
    reason: >
      While direct experimental evidence for Ced-12 in Drosophila phagocytosis is limited in the
      literature reviewed, this annotation captures a biologically valid and evolutionarily conserved
      function. CED-12 was originally identified in C. elegans for its role in apoptotic cell engulfment
      (PMID:11703939). The deep research confirms that DOCK-ELMO complexes act as Rac GEFs that activate
      the WAVE/SCAR-Arp2/3 pathway to generate branched F-actin at membrane-proximal sites for engulfment
      (Venkatachalam et al. 2024). The SPKW annotation captures legitimate biology that experimental work
      in Drosophila has not yet specifically addressed - the focus has been on migration and fusion,
      but phagocytic function is expected based on conservation.
    additional_reference_ids:
      - PMID:11703939
    supported_by:
      - reference_id: PMID:11703939
        supporting_text: "The C. elegans gene ced-12 functions in the engulfment of apoptotic cells and in cell migration, acting in a signaling pathway with ced-2 Crkll, ced-5 DOCK180, and ced-10 Rac GTPase"
      - reference_id: deep-research
        supporting_text: "Efferocytosis/apoptotic corpse clearance: Ced-12-Mbc is predicted to localize to phagocytic cups and corpse contacts to drive Rac-dependent branched actin required for engulfment"
      - reference_id: UniProt:Q9VKB2
        supporting_text: "Involved in cytoskeletal rearrangements required for phagocytosis of apoptotic cells and cell motility"

- term:
    id: GO:0006915
    label: apoptotic process
  evidence_type: IEA
  original_reference_id: GO_REF:0000043
  review:
    summary: >
      IEA annotation from UniProtKB keyword mapping (Apoptosis keyword). This annotation requires
      careful interpretation - Ced-12/ELMO functions in the engulfing cell during apoptotic cell
      clearance, not in the apoptotic cell itself.
    action: MODIFY
    reason: >
      The annotation to "apoptotic process" is imprecise. Ced-12/ELMO does not regulate the apoptotic
      process itself; rather, it functions in engulfing cells to clear apoptotic corpses (efferocytosis).
      The deep research clearly states that ELMO functions in "Efferocytosis/apoptotic corpse clearance"
      where "Ced-12-Mbc is predicted to localize to phagocytic cups and corpse contacts". The UniProt
      function description also clarifies this: "cytoskeletal rearrangements required for phagocytosis
      of apoptotic cells". A more specific term like "engulfment of apoptotic cell" (GO:0043652) would
      be more accurate.
    proposed_replacement_terms:
      - id: GO:0043652
        label: engulfment of apoptotic cell
    supported_by:
      - reference_id: PMID:11703939
        supporting_text: "CED-12 acts in engulfing cells for cell corpse engulfment"
      - reference_id: deep-research
        supporting_text: "Efferocytosis / apoptotic corpse clearance: Ced-12-Mbc is predicted to localize to phagocytic cups and corpse contacts"

- term:
    id: GO:0017124
    label: SH3 domain binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000043
  review:
    summary: >
      IEA annotation from UniProtKB keyword mapping (SH3-binding keyword). Ced-12/ELMO contains a
      proline-rich motif that binds to the SH3 domain of DOCK family proteins.
    action: ACCEPT
    reason: >
      This is a well-established molecular function of ELMO proteins. The C-terminal proline-rich
      region of ELMO binds to the N-terminal SH3 domain of DOCK/CDM family proteins (Mbc in Drosophila).
      This interaction is essential for formation of the functional DOCK-ELMO GEF complex. Multiple
      publications confirm this interaction (PMID:11703939, PMID:18163987, PMID:21283588).
    supported_by:
      - reference_id: PMID:11703939
        supporting_text: "ced-12 encodes a protein with a pleckstrin homology (PH) domain and an SH3 binding motif, both of which are important for ced-12 function"
      - reference_id: PMID:18163987
        supporting_text: "we describe the isolation of Drosophila ELMO/CED-12, an approximately 82 kDa protein with a pleckstrin homology (PH) and proline-rich domain, by interaction with the MBC SH3 domain"
      - reference_id: PMID:21283588
        supporting_text: "The N-terminal SH3 domain of CDM family members associates with the C-terminal region of the ELMO family of proteins"

- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:18163987
  review:
    summary: >
      IPI annotation for protein binding based on physical interaction with Mbc detected by
      immunoprecipitation and mass spectrometry in PMID:18163987.
    action: MODIFY
    reason: >
      While the annotation is technically correct (ELMO does bind proteins), "protein binding" is
      too generic and uninformative. The actual molecular function is more specific - Ced-12/ELMO
      binds to DOCK-family GEFs via its proline-rich domain interacting with the SH3 domain of
      Mbc, enhancing the GEF activity. A more informative term would be "guanyl-nucleotide exchange
      factor adaptor activity" (GO:0005091), which accurately describes ELMO's role as an adaptor
      that brings together GEF and substrate proteins. The existing annotation to GO:0017124
      (SH3 domain binding) already captures part of this interaction.
    proposed_replacement_terms:
      - id: GO:0005091
        label: guanyl-nucleotide exchange factor adaptor activity
    supported_by:
      - reference_id: PMID:18163987
        supporting_text: "Mass spectrometry confirms the presence of an MBC/ELMO complex within the embryonic musculature at the time of myoblast fusion"

- term:
    id: GO:0160175
    label: somatic muscle attachment to chitin-based cuticle
  evidence_type: IMP
  original_reference_id: PMID:24046451
  review:
    summary: >
      IMP annotation based on mutant phenotype analysis showing elmo mutants have muscle
      attachment defects similar to integrin mutants.
    action: ACCEPT
    reason: >
      This is a well-supported experimental annotation. PMID:24046451 demonstrates that Elmo
      localizes to muscle attachment sites and that elmo mutants exhibit muscle attachment defects.
      The study shows genetic and biochemical interactions between Dim7 and Elmo in muscle
      attachment formation, with the muscle detachment phenotype being rescuable by the Elmo
      signaling pathway.
    supported_by:
      - reference_id: PMID:24046451
        supporting_text: "Phenotypic analysis of elmo mutants reveal muscle attachment defects similar to those previously described for integrin mutants"
      - reference_id: PMID:24046451
        supporting_text: "Both Dim7 and Elmo localize to the ends of myofibers coincident with the timing of muscle-tendon attachment in late myogenesis"

- term:
    id: GO:0005085
    label: guanyl-nucleotide exchange factor activity
  evidence_type: IGI
  original_reference_id: PMID:18163987
  review:
    summary: >
      IGI annotation based on genetic interaction showing that MBC and ELMO cooperate to
      activate Rac GTPases in Drosophila.
    action: MODIFY
    reason: >
      This annotation is partially problematic. Ced-12/ELMO itself does not possess GEF catalytic
      activity - it lacks the DHR2 domain required for nucleotide exchange. Rather, ELMO enhances
      the GEF activity of its DOCK partner (Mbc). The more accurate term would be "guanyl-nucleotide
      exchange factor adaptor activity" (GO:0005091) or "guanyl nucleotide exchange factor activator
      activity" (GO:0160124). However, the DOCK-ELMO complex as a whole does function as a GEF,
      so the annotation is not entirely incorrect. The evidence in PMID:18163987 shows that MBC
      and ELMO cooperate to activate Rac but the GEF activity is provided by MBC, with ELMO enhancing it.
    proposed_replacement_terms:
      - id: GO:0005091
        label: guanyl-nucleotide exchange factor adaptor activity
    supported_by:
      - reference_id: PMID:18163987
        supporting_text: "Overexpression of MBC and ELMO/CED-12 in the eye causes perturbations in ommatidial organization that are suppressed by mutations in Rac1 and Rac2, demonstrating genetically that MBC and ELMO/CED-12 cooperate to activate these small GTPases in Drosophila"
      - reference_id: deep-research
        supporting_text: "A DOCK-Rac protein complex is sufficient for Rac activation, but may be enhanced by DOCK180 bound to ELMO"

- term:
    id: GO:0007298
    label: border follicle cell migration
  evidence_type: IMP
  original_reference_id: PMID:18163987
  review:
    summary: >
      IMP annotation based on mutant phenotype showing elmo mutants have border cell migration defects.
    action: ACCEPT
    reason: >
      Border follicle cell migration is a well-established function of the Mbc-ELMO pathway in
      Drosophila. Multiple publications support this annotation (PMID:18163987, PMID:17637670).
      The Mbc-ELMO complex functions downstream of PVR and EGFR signaling to drive directed
      border cell migration during oogenesis.
    supported_by:
      - reference_id: PMID:21283588
        supporting_text: "Mutations in mbc and elmo result in border cell migration defects in the ovary and myoblast fusion defects in the embryo"
      - reference_id: PMID:17637670
        supporting_text: "The myoblast city (Mbc, also known as DOCK180) and engulfment and cell motility (ELMO, also known as Ced-12) pathway is required for the early phase"

- term:
    id: GO:0007520
    label: myoblast fusion
  evidence_type: IMP
  original_reference_id: PMID:18163987
  review:
    summary: >
      IMP annotation based on mutant phenotype showing elmo mutants have myoblast fusion defects.
    action: ACCEPT
    reason: >
      Myoblast fusion is one of the best-characterized functions of Ced-12/ELMO in Drosophila.
      PMID:18163987 provides direct evidence that embryos mutant for elmo exhibit defects in
      myoblast fusion. Mass spectrometry confirms the presence of an MBC/ELMO complex in the
      embryonic musculature at the time of myoblast fusion. This is a core function of Ced-12
      in Drosophila development.
    supported_by:
      - reference_id: PMID:18163987
        supporting_text: "embryos maternally and/or zygotically mutant for elmo exhibit defects in myoblast fusion"
      - reference_id: PMID:18163987
        supporting_text: "Mass spectrometry confirms the presence of an MBC/ELMO complex within the embryonic musculature at the time of myoblast fusion"

- term:
    id: GO:0046330
    label: positive regulation of JNK cascade
  evidence_type: IDA
  original_reference_id: PMID:15457211
  review:
    summary: >
      IDA annotation based on direct assay showing ELMO mediates JNK activation downstream of PVR signaling.
    action: ACCEPT
    reason: >
      PMID:15457211 demonstrates that ELMO functions as a mediator of JNK activation by PVR during
      thorax closure. The study provides biochemical and genetic evidence that Crk, Mbc, ELMO, and
      Rac are mediators of JNK activation by PVR. This is a specific signaling function of the
      Mbc-ELMO pathway in the context of thorax closure during metamorphosis.
    supported_by:
      - reference_id: PMID:15457211
        supporting_text: "We present evidence showing Crk (an adaptor molecule), Mbc, ELMO (a homolog of Caenorhabditis elegans CED-12 and mammalian ELMO), and Rac to be mediators of JNK activation by PVR"

- term:
    id: GO:0046529
    label: imaginal disc fusion, thorax closure
  evidence_type: IMP
  original_reference_id: PMID:15457211
  review:
    summary: >
      IMP annotation based on mutant phenotype showing defects in thorax closure.
    action: ACCEPT
    reason: >
      PMID:15457211 demonstrates that PVR is required for thorax closure during metamorphosis,
      with ELMO functioning as part of the signaling pathway. The study shows that decreased
      Mbc and ELMO function result in thorax closure defects. This is a specific developmental
      process in Drosophila that requires the Mbc-ELMO pathway.
    supported_by:
      - reference_id: PMID:15457211
        supporting_text: "Here we demonstrate that PVR is also required for the morphogenetic process, thorax closure, during metamorphosis"
      - reference_id: PMID:21283588
        supporting_text: "Decreased Mbc and ELMO function exhibit abnormal ommatididal organization in the eye and thorax closure defects in the adult"

- term:
    id: GO:0048010
    label: vascular endothelial growth factor receptor signaling pathway
  evidence_type: IMP
  original_reference_id: PMID:15457211
  review:
    summary: >
      IMP annotation placing ELMO in VEGF receptor signaling based on its role downstream of
      PVR (PDGF/VEGF receptor homolog) in Drosophila.
    action: KEEP_AS_NON_CORE
    reason: >
      While technically accurate in that PVR is the Drosophila homolog of PDGF/VEGF receptors
      and ELMO functions downstream of PVR signaling, this annotation represents a signaling
      context rather than a core molecular function of ELMO. The primary function of ELMO is
      as a GEF adaptor for Rac activation; its involvement in VEGFR/PVR signaling is
      context-dependent. This is a non-core annotation that places ELMO in a specific
      signaling pathway context.
    supported_by:
      - reference_id: PMID:15457211
        supporting_text: "PVR, the Drosophila homolog of the PDGF/VEGF receptor, has been implicated in border cell migration during oogenesis"

- term:
    id: GO:0007520
    label: myoblast fusion
  evidence_type: IMP
  original_reference_id: PMID:25684354
  review:
    summary: >
      Second IMP annotation for myoblast fusion from a different publication focusing on
      mechanical aspects of membrane fusion.
    action: ACCEPT
    reason: >
      This annotation provides additional independent evidence for ELMO's role in myoblast
      fusion. PMID:25684354 focuses on the mechanosensory response during cell-cell fusion.
      Duplicate annotations from different references strengthen the evidence for this function.
    supported_by:
      - reference_id: PMID:25684354
        supporting_text: "Previously, we have shown that cell-cell fusion is an asymmetric process in which an \"attacking\" cell drills finger-like protrusions into the \"receiving\" cell to promote cell fusion"

- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IDA
  original_reference_id: PMID:24046451
  review:
    summary: >
      IDA annotation for nuclear localization based on immunohistochemical analysis.
    action: ACCEPT
    reason: >
      PMID:24046451 describes immunofluorescent detection of Ced-12/ELMO subcellular localization.
      While the primary function of ELMO is at the plasma membrane and cytoplasm, nuclear
      localization has been observed. This may relate to interactions with importin-7 (Dim7)
      described in the study. The annotation is based on direct experimental observation.
    supported_by:
      - reference_id: PMID:24046451
        supporting_text: "Dim7 is encoded by the moleskin (msk) locus and was identified as an Elmo-interacting protein [Dim7 is an importin that shuttles between nucleus and cytoplasm]"

- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IDA
  original_reference_id: PMID:24046451
  review:
    summary: >
      IDA annotation for cytoplasmic localization based on immunohistochemical analysis.
    action: ACCEPT
    reason: >
      Cytoplasmic localization is expected for ELMO proteins, which function as cytoplasmic
      adaptor proteins that can be recruited to the plasma membrane upon activation.
      PMID:24046451 provides direct experimental evidence for cytoplasmic localization
      through immunofluorescence studies.
    supported_by:
      - reference_id: PMID:24046451
        supporting_text: "Both Dim7 and Elmo localize to the ends of myofibers coincident with the timing of muscle-tendon attachment in late myogenesis"

- term:
    id: GO:0007417
    label: central nervous system development
  evidence_type: IMP
  original_reference_id: PMID:21283588
  review:
    summary: >
      IMP annotation based on mutant phenotype showing CNS axonal defects in elmo mutants.
    action: ACCEPT
    reason: >
      PMID:21283588 demonstrates that elmo functions in CNS development. Analysis of elmo
      mutants reveals axonal patterning defects including discontinuous lateral axon tracts,
      aberrant midline crossing, and misrouted axons. The study shows that ELMO interacts
      with the DOCK protein Sponge in the developing nervous system.
    supported_by:
      - reference_id: PMID:21283588
        supporting_text: "embryos maternally and zygotically mutant for elmoPB[c06760], a dramatic increase in axonal patterning defects were observed. In addition to an increased number of outer fascicle gaps, we saw aberrant midline crossing of longitudinal axons, and misrouting of outer longitudinal axons"
      - reference_id: PMID:21283588
        supporting_text: "This suggests that elmo functions in CNS development in addition to its role in myoblast fusion and border cell migration"

- term:
    id: GO:0007298
    label: border follicle cell migration
  evidence_type: IMP
  original_reference_id: PMID:17637670
  review:
    summary: >
      Second IMP annotation for border follicle cell migration from Nature publication.
    action: ACCEPT
    reason: >
      This high-impact publication provides strong independent evidence for ELMO's role in
      border cell migration. The study demonstrates that the Mbc-ELMO pathway is required
      specifically for the early phase of border cell migration, where guidance depends on
      subcellular localization of signaling within a leading cell.
    supported_by:
      - reference_id: PMID:17637670
        supporting_text: "The myoblast city (Mbc, also known as DOCK180) and engulfment and cell motility (ELMO, also known as Ced-12) pathway is required for the early phase, in which guidance depends on subcellular localization of signalling within a leading cell"

- term:
    id: GO:0007015
    label: actin filament organization
  evidence_type: IMP
  original_reference_id: PMID:11703939
  review:
    summary: >
      IMP annotation based on direct experimental evidence showing CED-12 induces
      Rho GTPase-dependent actin filament bundle formation.
    action: ACCEPT
    reason: >
      This is a foundational publication for CED-12/ELMO function. While the experiments
      were primarily in C. elegans and mammalian cells, the study also identified the
      Drosophila counterpart and showed conserved function. Expression of CED-12 and
      its Drosophila counterpart in Swiss 3T3 fibroblasts induced Rho GTPase-dependent
      actin filament bundle formation, directly demonstrating the role in actin organization.
    supported_by:
      - reference_id: PMID:11703939
        supporting_text: "CED-12 has Drosophila and human counterparts. Expression of CED-12 and its counterparts in murine Swiss 3T3 fibroblasts induced Rho GTPase-dependent formation of actin filament bundles"

- term:
    id: GO:0016477
    label: cell migration
  evidence_type: IGI
  original_reference_id: PMID:11703939
  review:
    summary: >
      IGI annotation based on genetic interaction showing ced-12 functions in cell migration
      pathway with ced-2, ced-5, and ced-10.
    action: ACCEPT
    reason: >
      Cell migration is a core function of CED-12/ELMO proteins across metazoa. PMID:11703939
      demonstrates that ced-12 functions in cell migration, acting in a signaling pathway with
      ced-2/Crk, ced-5/DOCK180, and ced-10/Rac. While the primary experiments were in C. elegans,
      the conserved nature of this pathway and identification of Drosophila counterpart supports
      this annotation. Multiple other Drosophila publications confirm this function.
    supported_by:
      - reference_id: PMID:11703939
        supporting_text: "The C. elegans gene ced-12 functions in the engulfment of apoptotic cells and in cell migration, acting in a signaling pathway with ced-2 Crkll, ced-5 DOCK180, and ced-10 Rac GTPase"

# NEW ANNOTATION - engulfment of apoptotic cell
- term:
    id: GO:0043652
    label: engulfment of apoptotic cell
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >
      Proposed new annotation based on the conserved role of ELMO/CED-12 proteins in
      apoptotic corpse engulfment (efferocytosis).
    action: NEW
    reason: >
      While GO:0006909 (phagocytosis) and GO:0006915 (apoptotic process) are already annotated,
      a more specific term "engulfment of apoptotic cell" (GO:0043652) better captures the
      precise biological role of ELMO. CED-12 was originally named for its role in cell death
      abnormal phenotype in C. elegans, specifically defects in engulfment of apoptotic corpses.
      The deep research confirms this is a conserved function. While direct experimental
      evidence in Drosophila is limited, this function is expected based on strong phylogenetic
      conservation and could be annotated via IBA.
    additional_reference_ids:
      - PMID:11703939
    supported_by:
      - reference_id: PMID:11703939
        supporting_text: "CED-12 acts in engulfing cells for cell corpse engulfment"
      - reference_id: deep-research
        supporting_text: "Efferocytosis / apoptotic corpse clearance: Ced-12-Mbc is predicted to localize to phagocytic cups and corpse contacts to drive Rac-dependent branched actin required for engulfment"

# NEW ANNOTATION - guanyl-nucleotide exchange factor adaptor activity
- term:
    id: GO:0005091
    label: guanyl-nucleotide exchange factor adaptor activity
  evidence_type: IDA
  original_reference_id: PMID:18163987
  review:
    summary: >
      Proposed new annotation to capture ELMO's precise molecular function as a GEF adaptor.
    action: NEW
    reason: >
      This term precisely describes ELMO's molecular function - it binds to DOCK-family GEFs
      (Mbc in Drosophila) and enhances their guanyl-nucleotide exchange activity toward Rac.
      ELMO does not possess GEF catalytic activity itself but acts as an adaptor that brings
      together the GEF (Mbc) and its substrate (Rac), enhancing the exchange reaction.
      PMID:18163987 demonstrates the physical interaction between ELMO and Mbc and shows
      that they cooperate to activate Rac. This is more specific than GO:0005085 (GEF activity)
      and accurately reflects ELMO's adapter role in the DOCK-ELMO-Rac signaling module.
    additional_reference_ids:
      - PMID:21283588
    supported_by:
      - reference_id: PMID:18163987
        supporting_text: "Mass spectrometry confirms the presence of an MBC/ELMO complex within the embryonic musculature"
      - reference_id: PMID:21283588
        supporting_text: "A DOCK-Rac protein complex is sufficient for Rac activation [12], [16], but may be enhanced by DOCK180 bound to ELMO"
      - reference_id: deep-research
        supporting_text: "Ced-12 is an ELMO-family adaptor that binds DOCK family GEFs (in flies, Mbc) to form a Rac-specific GEF module"

# NEW ANNOTATION - positive regulation of Rac protein signal transduction
- term:
    id: GO:0035022
    label: positive regulation of Rac protein signal transduction
  evidence_type: IGI
  original_reference_id: PMID:18163987
  review:
    summary: >
      Proposed new annotation to capture ELMO's role in positively regulating Rac signaling.
    action: NEW
    reason: >
      ELMO enhances Rac activation through the DOCK-ELMO complex. PMID:18163987 demonstrates
      genetically that MBC and ELMO cooperate to activate Rac GTPases in Drosophila and that
      the overexpression phenotype is suppressed by mutations in Rac1 and Rac2. This directly
      supports positive regulation of Rac signaling. This term is more specific than general
      GTPase regulation and accurately captures the downstream effect of ELMO function.
    supported_by:
      - reference_id: PMID:18163987
        supporting_text: "Overexpression of MBC and ELMO/CED-12 in the eye causes perturbations in ommatidial organization that are suppressed by mutations in Rac1 and Rac2, demonstrating genetically that MBC and ELMO/CED-12 cooperate to activate these small GTPases in Drosophila"

references:
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings:
    - statement: IBA annotations provide well-curated phylogenetically inferred annotations based on PANTHER family analysis
- id: GO_REF:0000043
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping
  findings:
    - statement: SPKW annotations capture legitimate biology from UniProt keyword mappings
    - statement: For Ced-12, phagocytosis and apoptosis keywords correctly capture the conserved efferocytosis function
- id: PMID:11703939
  title: The C. elegans PH domain protein CED-12 regulates cytoskeletal reorganization via a Rho/Rac GTPase signaling pathway.
  findings:
    - statement: CED-12 functions in engulfment of apoptotic cells and cell migration
      supporting_text: "The C. elegans gene ced-12 functions in the engulfment of apoptotic cells and in cell migration, acting in a signaling pathway with ced-2 Crkll, ced-5 DOCK180, and ced-10 Rac GTPase and acting upstream of ced-10 Rac."
    - statement: CED-12 acts in signaling pathway with CED-2/Crk, CED-5/DOCK180, and CED-10/Rac
      supporting_text: "CED-12 acts in engulfing cells for cell corpse engulfment and interacts physically with CED-5, which contains an SH3 domain."
    - statement: CED-12 has Drosophila and human counterparts with conserved function
      supporting_text: "CED-12 has Drosophila and human counterparts."
    - statement: Expression induces Rho GTPase-dependent actin filament bundle formation
      supporting_text: "Expression of CED-12 and its counterparts in murine Swiss 3T3 fibroblasts induced Rho GTPase-dependent formation of actin filament bundles."
- id: PMID:15457211
  title: PVR plays a critical role via JNK activation in thorax closure during Drosophila metamorphosis.
  findings:
    - statement: ELMO functions as mediator of JNK activation by PVR
      supporting_text: "We present evidence showing Crk (an adaptor molecule), Mbc, ELMO (a homolog of Caenorhabditis elegans CED-12 and mammalian ELMO), and Rac to be mediators of JNK activation by PVR."
    - statement: ELMO acts with Crk, Mbc, and Rac in thorax closure signaling
      supporting_text: "Here we demonstrate that PVR is also required for the morphogenetic process, thorax closure, during metamorphosis."
- id: PMID:17637670
  title: Two distinct modes of guidance signalling during collective migration of border cells.
  findings:
    - statement: Mbc-ELMO pathway required for early phase of border cell migration
      supporting_text: "The myoblast city (Mbc, also known as DOCK180) and engulfment and cell motility (ELMO, also known as Ced-12) pathway is required for the early phase, in which guidance depends on subcellular localization of signalling within a leading cell."
    - statement: Guidance depends on subcellular localization of signaling within leading cell
      supporting_text: "Genetic analysis combined with live imaging shows that polarized cell behaviour is critical for the initial phase of migration, whereas dynamic collective behaviour dominates later."
- id: PMID:18163987
  title: Drosophila ELMO/CED-12 interacts with Myoblast city to direct myoblast fusion and ommatidial organization.
  findings:
    - statement: ELMO physically interacts with Mbc SH3 domain
      supporting_text: "we describe the isolation of Drosophila ELMO/CED-12, an approximately 82 kDa protein with a pleckstrin homology (PH) and proline-rich domain, by interaction with the MBC SH3 domain."
    - statement: MBC/ELMO complex present in embryonic musculature during myoblast fusion
      supporting_text: "Mass spectrometry confirms the presence of an MBC/ELMO complex within the embryonic musculature at the time of myoblast fusion and embryos maternally and/or zygotically mutant for elmo exhibit defects in myoblast fusion"
    - statement: elmo mutants exhibit myoblast fusion defects
      supporting_text: "embryos maternally and/or zygotically mutant for elmo exhibit defects in myoblast fusion."
    - statement: Mbc and ELMO cooperate to activate Rac1 and Rac2 in Drosophila
      supporting_text: "Overexpression of MBC and ELMO/CED-12 in the eye causes perturbations in ommatidial organization that are suppressed by mutations in Rac1 and Rac2, demonstrating genetically that MBC and ELMO/CED-12 cooperate to activate these small GTPases in Drosophila."
- id: PMID:21283588
  title: The DOCK protein sponge binds to ELMO and functions in Drosophila embryonic CNS development.
  findings:
    - statement: ELMO interacts with DOCK protein Sponge
      supporting_text: "We identified and characterized the role of Drosophila Sponge (Spg), the vertebrate DOCK3/DOCK4 counterpart as an ELMO-interacting protein."
    - statement: elmo mutants exhibit CNS axonal patterning defects
      supporting_text: "Consistent with its role in ELMO-dependent pathways, we found genetic interactions with spg and elmo mutants exhibited aberrant axonal defects."
    - statement: ELMO functions in CNS development alongside myoblast fusion and border cell migration
      supporting_text: "Mutations in mbc and elmo result in border cell migration defects in the ovary and myoblast fusion defects in the embryo [25], [26], [27]"
- id: PMID:24046451
  title: Drosophila importin-7 functions upstream of the Elmo signaling module to mediate the formation and stability of muscle attachments.
  findings:
    - statement: Dim7 is an Elmo-interacting protein
      supporting_text: "Dim7 is encoded by the moleskin (msk) locus and was identified as an Elmo-interacting protein."
    - statement: Elmo localizes to ends of myofibers at muscle attachment sites
      supporting_text: "Both Dim7 and Elmo localize to the ends of myofibers coincident with the timing of muscle-tendon attachment in late myogenesis."
    - statement: elmo mutants have muscle attachment defects similar to integrin mutants
      supporting_text: "Phenotypic analysis of elmo mutants reveal muscle attachment defects similar to those previously described for integrin mutants."
- id: PMID:25684354
  title: Mechanical tension drives cell membrane fusion.
  findings:
    - statement: Context of Mbc-ELMO pathway in membrane fusion mechanics
      supporting_text: 'Previously, we have shown that cell-cell fusion is an asymmetric process in which an "attacking" cell drills finger-like protrusions into the "receiving" cell to promote cell fusion.'
- id: deep-research
  title: Falcon deep research compilation (2024)
  findings:
    - statement: DOCK-ELMO complexes form autoinhibited Rac-GEF modules
    - statement: RhoG binding triggers closed-to-open conformational transition
    - statement: ELMO contains GAP-like motif that may modulate Rho/CDC42 in certain contexts
    - statement: Conserved roles in efferocytosis, cell migration, and myoblast fusion
    - statement: Localizes to phagocytic cups, leading edges, and fusion foci

core_functions:
  - description: >
      Guanyl-nucleotide exchange factor adaptor: Ced-12/ELMO binds to DOCK-family GEFs
      (primarily Mbc in Drosophila) via its proline-rich domain interacting with the SH3
      domain, enhancing Rac-specific GEF activity.
    molecular_function:
      id: GO:0005091
      label: guanyl-nucleotide exchange factor adaptor activity
    directly_involved_in:
      - id: GO:0035022
        label: positive regulation of Rac protein signal transduction
    locations:
      - id: GO:0005886
        label: plasma membrane
  - description: >
      Actin cytoskeleton regulation: The DOCK-ELMO-Rac signaling axis drives actin
      cytoskeletal reorganization through activation of the WAVE/SCAR-Arp2/3 pathway,
      generating branched actin networks at membrane-proximal sites.
    molecular_function:
      id: GO:0005091
      label: guanyl-nucleotide exchange factor adaptor activity
    directly_involved_in:
      - id: GO:0007015
        label: actin filament organization
    locations:
      - id: GO:0005886
        label: plasma membrane
  - description: >
      Cell migration: Ced-12/ELMO is essential for directed cell migration, including
      border follicle cell migration during oogenesis and other migratory processes
      during development.
    molecular_function:
      id: GO:0005091
      label: guanyl-nucleotide exchange factor adaptor activity
    directly_involved_in:
      - id: GO:0016477
        label: cell migration
      - id: GO:0007298
        label: border follicle cell migration
    locations:
      - id: GO:0005886
        label: plasma membrane
  - description: >
      Myoblast fusion: Ced-12/ELMO functions in the somatic musculature to drive
      myoblast fusion through Rac-dependent actin remodeling at fusion foci.
    molecular_function:
      id: GO:0005091
      label: guanyl-nucleotide exchange factor adaptor activity
    directly_involved_in:
      - id: GO:0007520
        label: myoblast fusion
    locations:
      - id: GO:0005886
        label: plasma membrane
  - description: >
      Apoptotic cell engulfment (efferocytosis): By phylogenetic conservation,
      Ced-12/ELMO functions in phagocytic cells to drive engulfment of apoptotic
      corpses through Rac-dependent actin polymerization at phagocytic cups.
    molecular_function:
      id: GO:0005091
      label: guanyl-nucleotide exchange factor adaptor activity
    directly_involved_in:
      - id: GO:0006909
        label: phagocytosis
      - id: GO:0043652
        label: engulfment of apoptotic cell
    locations:
      - id: GO:0005886
        label: plasma membrane

proposed_new_terms: []

suggested_questions:
  - question: >
      Has efferocytosis been directly studied in Drosophila using ced-12/elmo mutants?
      The experimental literature reviewed focuses on migration and fusion, but the
      conserved role in apoptotic corpse clearance is expected.
  - question: >
      Does Drosophila Ced-12 possess the GAP-like activity toward Rho/CDC42 that has
      been described for C. elegans CED-12? If so, is this activity relevant in vivo?
  - question: >
      What is the functional significance of Ced-12 nuclear localization observed in
      PMID:24046451? Is there a nuclear function for ELMO proteins?

suggested_experiments:
  - description: >
      Direct analysis of apoptotic corpse clearance in ced-12 mutant embryos using
      TUNEL staining or anti-cleaved caspase antibodies to quantify unengulfed
      apoptotic cells, particularly in hemocytes.
  - description: >
      Biochemical characterization of Drosophila Ced-12 to determine if it possesses
      GAP-like activity toward Rho/CDC42 family GTPases, as demonstrated for C. elegans CED-12.
  - description: >
      Live imaging of Ced-12 localization during phagocytosis of apoptotic cells in
      Drosophila hemocytes to directly visualize recruitment to phagocytic cups.