BNIP3 (CG5059) is the single Drosophila ortholog of the vertebrate mitophagy receptors BNIP3 and BNIP3L/NIX (NIP3 family, PANTHER PTHR15186). It is a 201-residue tail-anchored protein of the mitochondrial outer membrane. A C-terminal transmembrane helix anchors it in the membrane, and the N-terminal region faces the cytosol. That region carries an LC3-interacting region (LIR, WIEL at residues 16-19) and a minimal essential region (MER, residues 42-53). Fly BNIP3 acts as a receptor for selective autophagy of mitochondria (mitophagy). The LIR binds Atg8a and the MER binds the WIPI ortholog Atg18a, so BNIP3 recruits autophagic membranes to mitochondria. The two motifs act partly redundantly. BNIP3 is required for several developmentally programmed and stress-induced mitophagy programmes: removal of larval muscle mitochondria during metamorphic muscle remodelling; programmed germline mitophagy, which enforces mtDNA quality control in the ovary independently of PINK1 and Parkin; developmental mitochondrial clearance in the intestine, where it acts in a genetic pathway with Mtch, Vps13D, PINK1 and Parkin; hypoxia-induced mitophagy in larval muscle; and mitophagy in ageing flight muscle. Loss of BNIP3 is compatible with viability but causes mitochondria to accumulate in these tissues and shortens adult lifespan. Unlike vertebrate BNIP3, fly BNIP3 has no recognisable BH3 consensus. There is no experimental evidence in Drosophila for a pro-apoptotic role, nor for ER or ER-phagy receptor function.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000423 mitophagy | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT places mitophagy at the bilaterian PTHR15186 node (PTN001032684). The seeds are human BNIP3, worm DCT-1 and the fly gene itself. Fly BNIP3 is a well-established mitophagy receptor required in muscle, germline and intestine. Reason: The node placement is sound. Mitophagy receptor function is experimentally shown in vertebrates, nematodes and flies. FB:FBgn0037007 in the WITH/FROM reflects the fly gene's own experimental annotations used as descendant evidence for the IBD, so it is not circular. Fly-specific data agree: BNIP3 KO blocks mitophagy flux in remodelling muscle (PMID:40801807), and BNIP3 is needed for germline and intestinal mitophagy (PMID:36323236, PMID:37633267). Supporting Evidence: PMID:40801807 In sharp contrast, BNIP3 KO blocked mitophagy flux at a comparable level with FIP200 RNAi PMID:40801807 BNIP3 is the sole fly ortholog of mammalian NIX and BNIP3. |
| GO:0000423 mitophagy | IGI PMID:41576035 The conserved outer mitochondrial membrane protein Mtch regu... | ACCEPT | Summary: Restrepo et al. 2026 compared single and double mutants. Mtch and BNIP3 mutant enterocytes show the same failure to clear mitochondria (ATP5A retention) during intestinal development. This places BNIP3 in a common mitophagy pathway with Mtch, the MTCH2 ortholog and putative insertase for tail-anchored OMM proteins. Reason: Direct genetic evidence on the fly gene in a physiological mitophagy setting. The epistasis result (no enhancement in the double mutant) supports BNIP3 acting in the Mtch/Vps13D/PINK1/Parkin-dependent developmental mitophagy pathway of enterocytes. Supporting Evidence: PMID:41576035 These data indicate that Mtch and BNIP3 function in the same genetic pathway to control enterocyte mitophagy during intestine development. PMID:41576035 In addition, single and double mutant analyses of Mtch and Bnip3 mutants showed similar levels of elevated mitochondrial Atp5a, further indicating that these genes function in a common mitochondrial clearance genetic pathway. |
| GO:0000423 mitophagy | IMP PMID:36213625 Neuronal induction of BNIP3-mediated mitophagy slows systemi... | ACCEPT | Summary: Schmid et al. 2022 (Nat Aging) showed that neuronal induction of BNIP3 promotes mitophagy and prevents dysfunctional mitochondria from accumulating in the ageing brain. In the full text, however, the mitophagy experiments overexpressed a human BNIP3 transgene (UAS-hBNIP3-HA). The only loss-of-function experiment on fly BNIP3 (RNAi) measured lifespan, not mitophagy. Reason: The term is clearly correct for fly BNIP3 on independent loss-of-function grounds (PMID:40801807, PMID:37633267, PMID:41576035, PMID:36323236), so the annotation is accepted and the curator's judgement deferred to. Note, though, that this paper's direct mitophagy evidence comes from the human ortholog expressed in flies. The fly-gene experiment here (RNAi) shows only that BNIP3 is needed for normal lifespan. Supporting Evidence: PMID:36213625 To do so, we used Gene-Switch driver lines to express a UAS-hBNIP3-HA (hereafter BNIP3) transgene created by Zhang et al35. PMID:36213625 Up-regulation of BNIP3 in the adult nervous system is sufficient to induce mitophagy and prevent the accumulation of dysfunctional mitochondria in an autophagy-dependent manner. PMID:36213625 Conversely, expression of BNIP3-RNAi ubiquitously or specifically in neurons in adult flies resulted in shortened lifespans compared to controls |
| GO:0000423 mitophagy | IMP PMID:36323236 Mitochondrial DNA quality control in the female germline req... | ACCEPT | Summary: Palozzi et al. 2022 (Cell Metab) ran a large-scale screen in the female germline. They found that programmed germline mitophagy (PGM), which enforces mtDNA quality control, requires BNIP3 and the Atg1 complex but not PINK1/Parkin. Reason: Only the abstract is cached, but it states plainly that PGM requires BNIP3. The result agrees with Lieber et al. 2019 (germline RNAi of BNIP3 blocks mtDNA selection) and with the authors' Autophagy commentary. This is a core, PINK1/Parkin-independent mitophagy role. Supporting Evidence: PMID:36323236 We show that PGM requires the mitophagy receptor BNIP3, mitochondrial fission and translation factors, and members of the Atg1 complex, but not the mitophagy factors PINK1 and Parkin. PMID:31092924 Given these parallels, we asked whether CG5059 (BNIP3), the Drosophila protein most homologous to NIX/BNIP3L, was required for selection in the germline. PMID:36803283 Interestingly, PGM requires the general macroautophagy/autophagy machinery and the mitophagy adaptor BNIP3, but not the canonical mitophagy genes Pink1 and park (parkin), even though they are critical for germline mtDNA quality control. |
| GO:0000423 mitophagy | IMP PMID:37633267 PINK1, Keap1, and Rtnl1 regulate selective clearance of endo... | ACCEPT | Summary: Wang et al. 2023 made a CRISPR BNIP3 loss-of-function allele and used Cas9/gRNA clones. BNIP3 mutant enterocytes keep mitochondria (raised ATP5A) during developmental clearance at pupariation, which shows BNIP3 is required for mitophagy in the intestine. Reason: Direct loss-of-function evidence on the fly gene. The same paper shows the requirement is specific to mitochondria: ER clearance is not impaired, and ER-phagy flux actually rises in BNIP3 mutants. Supporting Evidence: PMID:37633267 These results indicate that BNIP3 is required for mitophagy in the same cells where Rtnl1, Trp1 and Atl are specifically required for ER-phagy. |
| GO:0000423 mitophagy | IMP PMID:40801807 Transcriptional dynamics uncover the role of BNIP3 in mitoph... | ACCEPT | Summary: Taoka et al. 2025 (eLife) studied BNIP3 KO and RNAi in dorsal internal oblique muscles, where larval muscle mitochondria normally go during metamorphic remodelling. Loss of BNIP3 blocks mitophagy flux (Mito-QC), stops mitophagosomes forming, and lets larval mitochondria accumulate. Full-length BNIP3 rescues; LIR+MER double mutants do not. Reason: The strongest fly evidence for this core process: KO, RNAi, reporter flux, EM and structure-function rescue. Supporting Evidence: PMID:40801807 BNIP3 is required for mitophagosome formation. PMID:40801807 However, at 4 d APF, the Mito-GFP signal was nearly absent in the control, while a strong Mito-GFP signal was observed in the BNIP3 KO (Figure 6D, Dβ), indicating that BNIP3-mediated mitophagy degrades larval muscle mitochondria during muscle remodeling. |
| GO:0000423 mitophagy | ISS PMID:37633267 PINK1, Keap1, and Rtnl1 regulate selective clearance of endo... | ACCEPT | Summary: Inferred from sequence similarity to human BNIP3 (Q12983). Wang et al. showed that the LIR residues needed for mammalian BNIP3 mitophagy-receptor function are conserved in fly. Reason: Sequence conservation of the LIR, MER and tail anchor (see the bioinformatics alignment) supports this, and fly loss-of-function data independently confirm it. Supporting Evidence: PMID:37633267 BNIP3 is conserved in Drosophila, including two amino acids in the LIR motif that are required for BNIP3 to function as a mitophagy receptor file:DROME/BNIP3/BNIP3-bioinformatics/RESULTS.md LIR: human WVEL (18-21) aligns without gaps to fly WIEL at residues 16-19. |
| GO:0005515 protein binding | IPI PMID:37061542 Next-generation large-scale binary protein interaction netwo... | REMOVE | Summary: A binary yeast two-hybrid interaction between BNIP3 and the reticulon Rtnl1 (Q9VMV9), from the FlyBi proteome-scale Drosophila binary interactome. Reason: Generic "protein binding" carries no functional information. This high-throughput Y2H pair has no functional follow-up that would support a more specific MF term. Removing it does not mean the interaction is false. Rtnl1 is an ER-phagy receptor, but fly BNIP3 is not required for ER-phagy (its loss raises ER-phagy flux, PMID:37633267), so no informative replacement can be inferred. The functionally validated partners (Atg8a via the LIR, Atg18a via the MER) are covered by GO:0140580 mitochondrion autophagosome adaptor activity. Supporting Evidence: PMID:37633267 In addition, ER-phagy flux is increased in BNIP3 mutant enterocytes compared to control intestine cells |
| GO:0005634 nucleus | HDA PMID:25294944 Subcellular localisations of the CPTI collection of YFP-tagg... | KEEP AS NON CORE | Summary: A high-throughput localization call from the Cambridge Protein Trap Insertion (CPTI) YFP-trap collection imaged in stage-5 embryos (Lye et al. 2014). The gene-level call is in the supplementary tables, which are not in the cached text. Reason: This is experimental fly data and the curator's reading of the supplement is not overruled. It is a single high-throughput observation of an internally YFP-tagged tail-anchored protein in early embryos. Every targeted localization study of BNIP3 in flies (fly GFP-BNIP3 in muscle, germline association with mitochondria, Mtch-dependent OMM insertion) places it at the mitochondrial outer membrane. No nuclear function has been described in Drosophila. Kept as a non-core location. Supporting Evidence: PMID:25294944 We focused on the 415 lines showing expression at stage 5 to determine their subcellular localisation and found that 258 YFP-trap proteins localised in the cytoplasm, 130 in the nucleus, 75 at the membrane and/or cortex and 13 in the extracellular space |
| GO:0005634 nucleus | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: A PAINT IBD at the bilaterian node PTN001032684, seeded only by vertebrate proteins (rat Bnip3, human BNIP3L and BNIP3). It asserts that the protein is active in the nucleus. Reason: "Is active in nucleus" asserts that the protein does its function in the nucleus. The vertebrate seeds reflect context-specific nuclear pools of BNIP3/NIX (for example in glioma, neurons and cardiomyocytes) that are minor relative to the mitochondrial pool. No invertebrate member has evidence of a nuclear activity, and every fly function described (mitophagy receptor activity) is carried out at the OMM. The fly HDA nuclear call (PMID:25294944) is a high-throughput localization, not evidence of nuclear activity. Placing a nuclear activity at the Bilateria node is not supported by invertebrate data. A high-throughput fly observation of nuclear signal does exist, so the row is kept as non-core (matching the HDA row) rather than marked as over-annotation, with the caveat that the node placement deserves PAINT re-examination. Propagation Review Root cause: NO FAILURE NON CORE Failure modes: CONTEXT OR TISSUE MISMATCH Sources checked: PANTHER:PTN001032684 SOURCE WEAK OR INFERRED Bilaterian node whose nucleus IBD is seeded only by vertebrate BNIP3/BNIP3L/rat Bnip3, which have context-specific minor nuclear pools; no invertebrate seed, and fly nuclear evidence is limited to one high-throughput YFP-trap call. Supporting Evidence: PMID:40801807 All BNIP3 constructs retain an intact TMD at the C-terminus, ensuring their localization to the outer mitochondrial membrane |
| GO:0005739 mitochondrion | IEA GO_REF:0000117 | ACCEPT | Summary: An ARBA machine-learning assignment of mitochondrial localization. Reason: Correct, though general. Fly BNIP3 is a mitochondrial outer membrane protein (PMID:40801807). GO:0005741 is the more informative term and is annotated separately. Supporting Evidence: PMID:31092924 BNIP3 is upregulated in differentiating cysts26 where it associated with mitochondria |
| GO:0005740 mitochondrial envelope | IEA GO_REF:0000002 | MODIFY | Summary: An InterPro2GO mapping from the BNIP3 family signature (IPR010548). Reason: Correct but less specific than the experimentally supported mitochondrial outer membrane (GO:0005741), a descendant the gene already carries. The fly GFP-BNIP3 imaging in PMID:40801807 places the protein in the outer membrane, and the InterPro BNIP3 family signature (IPR010548) supports membership of the tail-anchored NIP3/BNIP3 family, so the envelope term is refined to the outer membrane. Proposed replacements: mitochondrial outer membrane Supporting Evidence: PMID:40801807 GFP-BNIP3 constructs localize to the outer mitochondrial membrane. file:DROME/BNIP3/BNIP3-uniprot.txt InterPro; IPR010548; BNIP3. |
| GO:0005741 mitochondrial outer membrane | IBA GO_REF:0000033 | ACCEPT | Summary: A PAINT IBD at the bilaterian node, seeded by human BNIP3, human BNIP3L, worm DCT-1 and fly BNIP3. Reason: OMM residence through the C-terminal tail anchor is the defining, conserved feature of the family, and the site where the mitophagy receptor works. The fly gene appearing in its own WITH/FROM reflects its experimental OMM annotation and is not circular. Supporting Evidence: PMID:40801807 All BNIP3 constructs retain an intact TMD at the C-terminus, ensuring their localization to the outer mitochondrial membrane |
| GO:0005741 mitochondrial outer membrane | IDA PMID:41576035 The conserved outer mitochondrial membrane protein Mtch regu... | ACCEPT | Summary: Restrepo et al. 2026 show that Mtch, an OMM protein, is required for mitochondrial localization and stable levels of BNIP3 in fly enterocytes. They propose Mtch acts as an insertase for the tail-anchored BNIP3. Reason: The localization imaging in this paper used an HA-tagged human BNIP3 transgene in fly enterocytes. OMM residence of the fly protein is independently shown with fly GFP-BNIP3 (PMID:40801807), and the term is correct, so the curator's annotation is accepted. Supporting Evidence: PMID:41576035 Our data support a model with Mtch functioning as a BNIP3 insertase that is required for mitophagy downstream of PINK1 and Parkin PMID:40801807 GFP-BNIP3 constructs localize to the outer mitochondrial membrane. |
| GO:0005741 mitochondrial outer membrane | ISS PMID:37633267 PINK1, Keap1, and Rtnl1 regulate selective clearance of endo... | ACCEPT | Summary: Inferred from similarity to human BNIP3, a tail-anchored OMM protein. Reason: The C-terminal transmembrane tail anchor aligns gaplessly with human BNIP3, and fly experimental data confirm OMM localization. Supporting Evidence: file:DROME/BNIP3/BNIP3-bioinformatics/RESULTS.md Transmembrane domain: human TM 164-184 aligns gaplessly to fly 169-189 |
| GO:0016020 membrane | IEA GO_REF:0000120 | MODIFY | Summary: A combined electronic membrane annotation from the predicted single-pass TM helix. Reason: Correct but uninformative. The Phobius-predicted C-terminal helix (residues 166-188) supports membrane insertion, and fly GFP-BNIP3 imaging (PMID:40801807) shows the specific membrane is the mitochondrial outer membrane (GO:0005741), which the gene already carries. Proposed replacements: mitochondrial outer membrane Supporting Evidence: file:DROME/BNIP3/BNIP3-uniprot.txt TRANSMEM 166..188 PMID:40801807 GFP-BNIP3 constructs localize to the outer mitochondrial membrane. |
| GO:0031966 mitochondrial membrane | IEA GO_REF:0000044 | MODIFY | Summary: A UniProt subcellular-location mapping (Mitochondrion membrane). Reason: Correct but general: the UniProt location here rests on an ARBA rule, while fly GFP-BNIP3 imaging (PMID:40801807) resolves the membrane as the mitochondrial outer membrane (GO:0005741), a descendant the gene already carries. Proposed replacements: mitochondrial outer membrane Supporting Evidence: PMID:40801807 All BNIP3 constructs retain an intact TMD at the C-terminus, ensuring their localization to the outer mitochondrial membrane |
| GO:0042802 identical protein binding | IEA GO_REF:0000117 | KEEP AS NON CORE | Summary: An ARBA prediction of self-association, presumably reflecting the transmembrane-mediated homodimerisation documented for vertebrate BNIP3 and BNIP3L. Reason: No experiment has tested fly BNIP3 homodimerisation. The tail anchor keeps a glycine-rich GxxxG-like pattern (LGAGFG) like the dimerisation motif of human BNIP3, so the prediction is plausible. Kept as a non-core, sequence-based inference. Supporting Evidence: file:DROME/BNIP3/BNIP3-bioinformatics/RESULTS.md The fly TM keeps a GxxxG-like glycine pattern (LGAGFG), which in human BNIP3 mediates homodimerisation; this is a sequence observation, not a test of dimerisation. |
| GO:0043065 positive regulation of apoptotic process | IBA GO_REF:0000033 | MARK AS OVER ANNOTATED | Summary: A PAINT IBD at the bilaterian node PTN001032684. Every seed is a vertebrate protein (human, mouse, rat, zebrafish BNIP3/BNIP3L), and most come from overexpression-induced cell death assays. Reason: No Drosophila study shows a pro-apoptotic role for BNIP3. The available data point the other way. BNIP3 KO flies are viable. Overexpressing fly GFP-BNIP3 in larval muscle does not even induce mitophagy, and no toxicity was reported. Neuronal overexpression of human BNIP3 in flies reduced cleaved-caspase-3-positive cells in the aged brain. Fly BNIP3 has no recognisable BH3 consensus (only a W-rich segment aligns to the human BH3 region), and fly apoptosis is driven mainly by the IAP-antagonist pathway rather than BH3-only proteins. The vertebrate death activity may be a lineage-specific gain, or an overexpression phenotype, rather than an activity inherited at the Bilateria node. A latent death activity under strong overexpression has not been tested in flies, so this is marked as over-annotation rather than removed. Propagation Review Root cause: PROPAGATION BAD Failure modes: LINEAGE OR TAXON MISMATCH FUNCTIONAL DIVERGENCE Sources checked: PANTHER:PTN001032684 SUPPORTS SOURCE BUT NOT TARGET All seeds of this Bilateria-node IBD are vertebrate BNIP3/BNIP3L (human, mouse, rat, zebrafish), largely from overexpression death assays; no invertebrate member has in vivo pro-apoptotic evidence, and fly BNIP3 lacks a recognisable BH3 consensus. Supporting Evidence: PMID:36213625 Importantly, neuronal BNIP3 induction was associated with fewer apoptotic cells in the aged brain as detected by cleaved caspase-3 staining PMID:40801807 BNIP3 KO was compatible with viability and did not markedly impair mobility file:DROME/BNIP3/BNIP3-bioinformatics/RESULTS.md This alignment shows no recognisable BH3 consensus in fly BNIP3. It does not rule out a degenerate BH3-like element. |
| GO:0043065 positive regulation of apoptotic process | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: An InterPro2GO mapping from the BNIP3 family signature (IPR010548), reflecting the historical characterisation of mammalian BNIP3 as a pro-death BH3-only protein. Reason: Same reasoning as the IBA row. The family-signature mapping carries a vertebrate overexpression phenotype onto a fly protein that lacks a recognisable BH3 consensus and has no demonstrated death-promoting activity. Its established function is mitophagy receptor activity. Supporting Evidence: PMID:36213625 In the present study, we find that up-regulation of BNIP3 in adult neurons counteracts the accumulation of dysfunctional mitochondria in the aged brain, with no detectable induction of apoptosis in the aged brain. |
| GO:0043653 mitochondrial fragmentation involved in apoptotic process | IBA GO_REF:0000033 | MARK AS OVER ANNOTATED | Summary: A PAINT IBD at the bilaterian node with human BNIP3 as the only seed. The seed came from hypoxia/overexpression studies in mammalian cells, where BNIP3 drives DRP1-dependent fragmentation and cytochrome c release. Reason: There is no Drosophila evidence that BNIP3 fragments mitochondria in an apoptotic context, or that it promotes apoptosis at all (see the positive regulation of apoptotic process row). The single seed is a vertebrate BNIP3 paralog-specific observation. BNIP3L, the other vertebrate paralog, is not a seed, so it is unclear that the activity predates the BNIP3/BNIP3L duplication, let alone the Bilateria node. In flies, BNIP3-dependent clearance of mitochondria follows developmentally programmed fission and supports cell survival and remodelling, not death. Marked as over-annotation for the fly gene. Propagation Review Root cause: PROPAGATION BAD Failure modes: LINEAGE OR TAXON MISMATCH CONTEXT OR TISSUE MISMATCH Sources checked: PANTHER:PTN001032684 SUPPORTS SOURCE BUT NOT TARGET Single-seed IBD (human BNIP3, Q12983) from hypoxia/overexpression-induced mitochondrial fragmentation in mammalian cells; placed at the Bilateria node without invertebrate or BNIP3L support. Supporting Evidence: PMID:40801807 BNIP3-mediated mitophagy eliminates larval muscle mitochondria during muscle remodeling PMID:36213625 Cumulatively, these results suggest that neuronal BNIP3 induction can improve mitochondrial homeostasis while being neuroprotective. |
| GO:0061753 obsolete substrate localization to autophagosome | IEA GO_REF:0000108 | REMOVE | Summary: A logical-inference annotation derived from GO:0140580 to the term labelled "obsolete substrate localization to autophagosome". Reason: The GOA label itself marks the term as obsolete, so the annotation is not useful. The underlying biology (recruiting mitochondria to autophagic membranes) is fully captured by GO:0140580 mitochondrion autophagosome adaptor activity and GO:0000423 mitophagy. This matches the action taken for the same row on human BNIP3. |
| GO:0140580 mitochondrion autophagosome adaptor activity | IDA PMID:40801807 Transcriptional dynamics uncover the role of BNIP3 in mitoph... | ACCEPT | Summary: Taoka et al. 2025 show that fly BNIP3 recruits autophagic machinery to mitochondria. Its LIR binds Atg8a and its MER binds Atg18a. Atg18a co-immunoprecipitates with BNIP3 in a MER-dependent way. LIR+MER mutations abolish BNIP3-mediated mitochondrial clearance in vivo and stop BNIP3 itself being degraded by autophagy. Reason: This is the core molecular function. Binding to autophagosome-machinery proteins is shown, the binding motifs are mapped, and in vivo rescue shows the motifs are needed for mitochondrial clearance. Supporting Evidence: PMID:40801807 We confirmed that HA-tagged Drosophila Atg18a co-immunoprecipitated with GFP-tagged full-length Drosophila BNIP3, and that this interaction was attenuated by the deletion of the MER (residues 42β53) PMID:40801807 Furthermore, the combination of ΞLIR and ΞMER resulted in mitochondria accumulation nearly identical to that observed in BNIP3 KO flies PMID:40801807 From these results, we conclude that both MER and LIR motifs contribute to BNIP3-mediated mitophagy, with some redundancy in their contributions to selectivity. file:DROME/BNIP3/BNIP3-deep-research-falcon.md BNIP3 is an **outer-mitochondrial-membrane-associated receptor for selective autophagy of mitochondria (mitophagy)** |
| GO:0140580 mitochondrion autophagosome adaptor activity | ISS PMID:37633267 PINK1, Keap1, and Rtnl1 regulate selective clearance of endo... | ACCEPT | Summary: Inferred from human BNIP3, based on conservation of the two LIR residues needed for mitophagy-receptor function. Reason: Consistent with the direct fly evidence (PMID:40801807) and with LIR conservation. Supporting Evidence: PMID:37633267 BNIP3 is conserved in Drosophila, including two amino acids in the LIR motif that are required for BNIP3 to function as a mitophagy receptor |
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Download this section (compressed HTML)Q: Does fly BNIP3 have any cell-death-promoting activity when overexpressed at high levels? Is the W-rich segment that aligns with the vertebrate BH3 region a degenerate BH3 able to engage the fly Bcl-2 proteins Debcl or Buffy?
Q: Why does fly BNIP3 act independently of PINK1/Parkin in the germline but in one genetic pathway with Mtch, Vps13D, PINK1 and Parkin in enterocytes? Is the difference due to how BNIP3 is inserted and stabilised (Mtch-dependent) or to tissue-specific turnover (for example by an FBXL4 ortholog)?
Q: The PANTHER bilaterian node PTN001032684 carries vertebrate-only seeds for nucleus, positive regulation of apoptotic process and mitochondrial fragmentation involved in apoptotic process. Should these IBDs move to a vertebrate BNIP3/BNIP3L node, given no invertebrate support and the fly data against a pro-apoptotic role?
Experiment: Overexpress fly BNIP3 (wild type, LIR/MER mutants, and a variant with the W-rich segment mutated) at high levels in the larval eye disc and wing disc. Score apoptosis (cleaved Dcp-1, TUNEL, adult eye/wing phenotypes) with and without p35 or Diap1 co-expression. Test binding to Debcl and Buffy by co-IP.
Hypothesis: Fly BNIP3 lacks pro-apoptotic activity in vivo.
Type: in vivo overexpression and cell-death assay
Experiment: Make an endogenous N-terminal GFP knock-in of BNIP3 (keeping the tail anchor intact). Image embryos, ovaries, remodelling muscle and enterocytes, and do nuclear/mitochondrial fractionation, to test the high-throughput nuclear localization call.
Hypothesis: Endogenous fly BNIP3 is exclusively at the mitochondrial outer membrane, with no functional nuclear pool.
Type: endogenous tagging and localization
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Download this section (compressed HTML)BNIP3 encodes a mitochondrial autophagy (mitophagy) receptor.
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