grim encodes a short Drosophila Reaper/Hid/Grim-family IAP antagonist that promotes apoptotic caspase activation. Grim binds BIR domains of DIAP1/DIAP2-family IAPs through its N-terminal IAP-binding motif, countering IAP restraint of DrICE-family caspases, and also uses an internal GH3 amphipathic helix to associate with mitochondria and remodel cytochrome-c distribution during apoptosis induction in selected developmental cell-death programs. Grim expression also drives accumulation and processing of the caspase Dredd, and reducing dredd dosage suppresses grim-induced cell killing.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005515 protein binding | IPI PMID:18166655 DIAP2 functions as a mechanism-based regulator of drICE that... | MODIFY | Summary: Grim binds the DIAP2 BIR2 domain through its IAP-antagonist motif. Reason: The DIAP2 interaction is real and maps to a baculovirus IAP repeat domain, so BIR domain binding is the informative replacement for generic protein binding. Proposed replacements: BIR domain binding Supporting Evidence: PMID:18166655 Rpr and Grim preferentially bound to the BIR2 domain of DIAP2 |
| GO:0005634 nucleus | IDA PMID:21035895 Differential localization and processing of apoptotic protei... | KEEP AS NON CORE | Summary: Grim is detected in nuclei of Malpighian tubule cells that persist into adulthood. Reason: Nuclear sequestration of Grim in Malpighian tubules appears to be a tissue-specific survival context rather than the core pro-apoptotic site of Grim action. Supporting Evidence: PMID:21035895 sequestered in the nucleus |
| GO:0005737 cytoplasm | IDA PMID:21035895 Differential localization and processing of apoptotic protei... | UNDECIDED | Summary: The cached Malpighian-tubule abstract does not verify cytoplasmic Grim localization. Reason: The abstract reports nuclear sequestration of GRIM, HID, DRONC, and DRICE, but it does not expose the cytoplasmic staining that may have supported this IDA row. Supporting Evidence: PMID:21035895 sequestered in the nucleus |
| GO:0005737 cytoplasm | IDA PMID:9857177 Drosophila grim induces apoptosis in mammalian cells. | ACCEPT | Summary: Grim localizes partly to the cytosol when expressed in mouse fibroblasts. Reason: The localization was observed in heterologous mammalian cells and is consistent with the cytosolic pool observed in Drosophila cells before strong mitochondrial relocalization. Supporting Evidence: PMID:9857177 the cytosol and in the mitochondria of mouse fibroblasts |
| GO:0005739 mitochondrion | IDA PMID:9857177 Drosophila grim induces apoptosis in mammalian cells. | ACCEPT | Summary: Grim localizes to mitochondria in heterologous mammalian cells and in Drosophila SL2 cells during apoptosis induction. Reason: The PMID:9857177 source observed mitochondrial Grim in mouse fibroblasts, and the Drosophila SL2 GH3 study independently showed GH3-dependent mitochondrial association. Supporting Evidence: PMID:9857177 the cytosol and in the mitochondria of mouse fibroblasts PMID:12093734 Grim rings are mitochondria-associated |
| GO:0005759 mitochondrial matrix | IDA PMID:12093734 GH3, a novel proapoptotic domain in Drosophila Grim, promote... | MODIFY | Summary: Grim-positive rings surround mitochondrial markers rather than placing Grim in the matrix. Reason: The cited Drosophila microscopy used a mitochondrial matrix marker to show Grim-associated mitochondrial rings; it supports mitochondrion localization, not import into the matrix compartment. Proposed replacements: mitochondrion Supporting Evidence: PMID:12093734 Grim rings are mitochondria-associated |
| GO:0005886 plasma membrane | IDA PMID:21035895 Differential localization and processing of apoptotic protei... | UNDECIDED | Summary: The cached Malpighian-tubule abstract does not verify plasma-membrane Grim localization. Reason: Full-text figures may contain plasma-membrane staining, but the locally available abstract only exposes nuclear sequestration in Malpighian tubules. Supporting Evidence: PMID:21035895 sequestered in the nucleus |
| GO:0006915 apoptotic process | IDA PMID:11818065 The damage-responsive Drosophila gene sickle encodes a novel... | UNDECIDED | Summary: The cached Sickle abstract does not verify a Grim-specific apoptosis assay. Reason: PMID:11818065 uses Grim, Hid, and Reaper as IAP-antagonist comparators while characterizing Sickle; without full text, the Grim-specific IDA evidence behind this row is unresolved. Supporting Evidence: PMID:11818065 unlike the N termini of Grim, Hid, and Rpr |
| GO:0006915 apoptotic process | IEP PMID:8698237 grim, a novel cell death gene in Drosophila. | MODIFY | Summary: grim expression coincides with embryonic PCD and ectopic grim is sufficient to initiate p35-sensitive apoptosis. Reason: The original grim paper placed Grim upstream of ICE-like caspase effectors; that is a signaling role and is more specific than top-level apoptotic process. Proposed replacements: apoptotic signaling pathway Supporting Evidence: PMID:8698237 Expression of grim RNA coincided with the onset of programmed cell death |
| GO:0006915 apoptotic process | IMP PMID:12093734 GH3, a novel proapoptotic domain in Drosophila Grim, promote... | MODIFY | Summary: The Grim GH3 domain drives a mitochondrial apoptotic-signaling route. Reason: Loss of the GH3 domain blocks Grim pro-apoptotic function without disrupting IAP binding, supporting a specific mitochondrial signaling contribution rather than only the broad apoptotic-process term. Proposed replacements: apoptotic signaling pathway Supporting Evidence: PMID:12093734 deletion of the internal GH3 domain in a Grim protein still retaining the N-terminal domain also eliminates most of the Grim proapoptotic activity |
| GO:0006915 apoptotic process | IMP PMID:23940367 Caspase-dependent regulation of the ubiquitin-proteasome sys... | MODIFY | Summary: Caspase cleavage stabilizes Grim and amplifies the apoptotic signal. Reason: The DIAP1/UbcD1 study shows that Grim cleavage prevents K48-linked ubiquitinylation at Lys136 and starts a positive caspase-feedback branch, which is apoptotic signaling rather than the whole apoptotic process. Proposed replacements: apoptotic signaling pathway Supporting Evidence: PMID:23940367 feed-forward caspase amplification loop |
| GO:0006915 apoptotic process | IMP PMID:8698237 grim, a novel cell death gene in Drosophila. | MODIFY | Summary: Grim expression independently triggers caspase-dependent apoptotic signaling. Reason: Chen et al. showed that Grim can trigger p35-blockable apoptosis without rpr or hid, placing Grim in the signal that activates the shared downstream caspase machinery. Proposed replacements: apoptotic signaling pathway Supporting Evidence: PMID:8698237 did not require the functions of rpr or hid |
| GO:0008340 determination of adult lifespan | IMP PMID:16303568 Neuronal expression of p53 dominant-negative proteins in adu... | UNDECIDED | Summary: The cached p53/lifespan abstract does not mention grim. Reason: The PMID:16303568 abstract supports neuronal p53 dominant-negative effects on Drosophila lifespan, but Grim-specific full-text evidence is required before adjudicating this row. Supporting Evidence: PMID:16303568 adult neurons extends life span |
| GO:0010623 programmed cell death involved in cell development | IMP PMID:23519152 Essential role of grim-led programmed cell death for the est... | KEEP AS NON CORE | Summary: Grim is a developmental pro-apoptotic trigger in corazoninergic neuronal lineages. Reason: grim loss blocks developmental PCD of vCrz neurons and their EW3-sibling precursors; this is a real in vivo developmental context layered on top of Grim IAP-antagonist signaling. Supporting Evidence: PMID:23519152 We found grim as a chief proapoptotic gene |
| GO:0012501 programmed cell death | IMP PMID:20558283 grim promotes programmed cell death of Drosophila microchaet... | MODIFY | Summary: Grim is required for PCD of Drosophila microchaete glial cells. Reason: The source identifies an endogenous grim-dependent death process in one lineage; mechanistically this is another apoptotic-signaling context and can be represented more specifically than broad programmed cell death. Proposed replacements: apoptotic signaling pathway Supporting Evidence: PMID:20558283 required grim |
| GO:0035006 melanization defense response | IMP PMID:17356067 Crystal cell rupture after injury in Drosophila requires the... | UNDECIDED | Summary: The cached crystal-cell rupture abstract does not expose a grim-specific melanization phenotype. Reason: The abstract links crystal-cell rupture and melanization to JNK, Rho GTPases, Eiger, and dying hemocytes, but the local evidence does not name Grim; full text is needed to verify whether grim was assayed. Supporting Evidence: PMID:17356067 melanization of the clot matrix |
| GO:0035193 larval central nervous system remodeling | TAS PMID:10821983 Metamorphosis in drosophila and other insects: the fate of n... | UNDECIDED | Summary: The cached insect-metamorphosis review abstract does not verify a direct grim assertion. Reason: The source is a broad metamorphosis review that describes neuronal fates but does not expose the Grim evidence behind this TAS row in the local abstract. Supporting Evidence: PMID:10821983 die before and immediately after eclosion |
| GO:0042803 protein homodimerization activity | IPI PMID:23940367 Caspase-dependent regulation of the ubiquitin-proteasome sys... | KEEP AS NON CORE | Summary: Grim self-associates in cells while being ubiquitinylated by DIAP1. Reason: Self-association is experimentally supported and likely relevant to RHG complex behavior, but the row captures a modulatory property rather than the primary IAP-antagonist function. Supporting Evidence: PMID:23940367 Grim self-associates in cells |
| GO:0043065 positive regulation of apoptotic process | IDA PMID:15107838 Molecular mechanisms of DrICE inhibition by DIAP1 and remova... | ACCEPT | Summary: Grim antagonizes DIAP1 to relieve DrICE inhibition. Reason: The structural DIAP1 study directly places Grim with Reaper and Hid as RHG peptides that counter DIAP1-mediated inhibition of the effector caspase DrICE. Supporting Evidence: PMID:15107838 hence relieving DIAP1-mediated inhibition of DrICE |
| GO:0051402 neuron apoptotic process | IMP PMID:21558369 Coordinated expression of cell death genes regulates neurobl... | KEEP AS NON CORE | Summary: Grim is required for normal apoptosis of embryonic and larval neuroblasts. Reason: The neuroblast phenotypes are strong in vivo developmental evidence for Grim-triggered apoptosis in the nervous system, but the cellular context is secondary to the IAP-antagonist mechanism. Supporting Evidence: PMID:21558369 Deletion of grim alone blocks the death of neuroblasts in the larvae |
| GO:0051402 neuron apoptotic process | IMP PMID:23784845 Mechanisms of postecdysis-associated programmed cell death o... | KEEP AS NON CORE | Summary: Grim is the principal death inducer for CCAP peptidergic neurons during CNS metamorphosis. Reason: This is a real endogenous neuronal apoptosis context for Grim, but it is a cell-type deployment of Grim apoptotic signaling rather than a separate molecular activity. Supporting Evidence: PMID:23784845 grim functions as a principal death inducer |
| GO:0090200 positive regulation of release of cytochrome c from mitochondria | IDA PMID:12093734 GH3, a novel proapoptotic domain in Drosophila Grim, promote... | MODIFY | Summary: Grim redistributes mitochondrial cytochrome c signal but does not cause substantial free cytochrome-c release in Drosophila cells. Reason: The Drosophila data support GH3-dependent apoptotic mitochondrial remodeling; the cited paper explicitly distinguishes this phenotype from vertebrate-style free cytochrome c release into the cytosol. Proposed replacements: apoptotic mitochondrial changes Supporting Evidence: PMID:12093734 we thus found no substantial cytochrome c release to cytosol |
| GO:0097190 apoptotic signaling pathway | IGI PMID:10481910 The Drosophila caspase inhibitor DIAP1 is essential for cell... | ACCEPT | Summary: Grim genetically antagonizes DIAP1-dependent caspase restraint. Reason: The DIAP1 paper shows that HID blocks DIAP1 and argues that RPR and GRIM act similarly to disrupt productive IAP-caspase interactions. Supporting Evidence: PMID:10481910 RPR and GRIM can act similarly |
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Download this section (compressed HTML)Q: Should GO provide a molecular-function term for the Grim/Reaper/Sickle GH3-side mitochondrial effector activity, so this domain is not represented only by broad apoptotic mitochondrial changes process terms?
Q: Which endogenous Drosophila death contexts require Grim-DIAP2 binding in addition to canonical DIAP1 antagonism, given that DIAP2 is primarily curated as a drICE threshold regulator and Imd-pathway ubiquitin ligase?
Experiment: Use endogenous grim rescue transgenes carrying separable IAP-binding-motif and GH3 mutations to quantify which developmental death events require BIR-domain binding, mitochondrial association, or both domains.
Experiment: Image tagged Grim at endogenous expression levels with DIAP1, DIAP2, active DrICE, and mitochondrial markers to distinguish cytosolic, nuclear, and mitochondrial pools across cells that die versus survive.
grim (grim) encodes a member of the inhibitor of apoptotic protein antagonists. In response to death signals, it induces apoptosis of cells in the central nervous system. It is important particularly for the apoptosis of specific juvenile neurons during metamorphosis.
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