id: B0I1T8 gene_symbol: vwc2 product_type: PROTEIN status: COMPLETE taxon: id: NCBITaxon:7955 label: Danio rerio description: 'vwc2 (brorin; ZFIN ZDB-GENE-090313-315, chromosome 13) is the zebrafish ortholog of vertebrate VWC2/Brorin, supported by conserved exon-intron structure and by synteny: ikzf1 and fignl1 are its neighbours in zebrafish, mouse and gar. PANTHER pairs it with the divergent si:dkey-283b1.7 as a teleost genome duplication paralog, but synteny and other gene trees do not confirm that pairing. It encodes a 309-residue secreted protein. The signal peptide is followed by a divergent N-terminal region and a conserved core of two chordin-like von Willebrand factor C (VWFC) cysteine-rich domains. Like mouse Brorin, it acts as a secreted antagonist of BMP signalling. Injected brorin mRNA suppresses Smad1/5/8 phosphorylation and dorsalizes embryos, while knockdown raises phospho-Smad1/5/8 in the dorsal brain without activating Wnt signalling. The gene is expressed predominantly in the developing nervous system (diencephalon primordium from 16 hpf; later ventral telencephalon, prethalamus/alar hypothalamus, hindbrain, spinal cord, olfactory placode and pituitary). Morphants rescued by brorin mRNA show loss of subpallial (ventral telencephalic) identity, fewer GABAergic interneurons and oligodendrocytes, more astroglia, and failure of forebrain commissures. In mammals, Brorin is also an extracellular constituent of AMPA receptor complexes.' existing_annotations: - term: id: GO:0005576 label: extracellular region evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: is_active_in supporting_entities: - MGI:MGI:2442987 - MGI:MGI:2444069 - PANTHER:PTN002921765 review: summary: Extracellular region (IBA, brorin family node). action: ACCEPT reason: vwc2 encodes a signal-peptide-bearing secreted protein, and mouse Brorin is secreted. PANTHER node PTN002921765 covers both VWC2 and VWC2L (MGI donors Vwc2 and Vwc2l), so the property is ancestral to the brorin family. supported_by: - &id001 reference_id: PMID:28448525 supporting_text: Zebrafish Brorin is presumed to be a secreted protein composed of 309 amino acids with a putative 22-amino acid signaling sequence at its amino-terminus (Fig 1A). - reference_id: PMID:17400546 supporting_text: 'Mouse Brorin protein produced in cultured cells was efficiently secreted into the culture medium.' - term: id: GO:0005576 label: extracellular region evidence_type: IEA original_reference_id: GO_REF:0000044 qualifier: located_in supporting_entities: - UniProtKB-SubCell:SL-0243 review: summary: Extracellular region from the UniProt 'Secreted' keyword. action: ACCEPT reason: Consistent with the predicted signal peptide and the secretion of mouse Brorin. supported_by: - *id001 - term: id: GO:0007399 label: nervous system development evidence_type: IMP original_reference_id: PMID:19852960 qualifier: acts_upstream_of_or_within review: summary: IMP from the Brorin-like (vwc2l) paper, Miwa et al. 2009. action: UNDECIDED reason: The cached record is abstract-only. The abstract describes knockdown of Brorin-like, which is vwc2l, not brorin/vwc2. The authors' 2017 full-text paper says that their earlier work reported the brorin-like knockdown, and that the role of brorin itself in early neural development had not been elucidated. ZFIN lists no morpholino for this vwc2 row, while vwc2l carries two morpholinos from the same paper. This row may therefore reflect vwc2l data. Without the full text I cannot exclude a vwc2 experiment, so I do not remove it. The term itself is supported for vwc2 by PMID:28448525. supported_by: - reference_id: PMID:19852960 supporting_text: The inhibition of Brorin-like functions in zebrafish resulted in the impairment of neural development. - reference_id: PMID:28448525 supporting_text: The amino acid sequence of Brorin is similar to that of Brorin-like/vwc2l, and we previously reported the expression of brorin-like and phenotype of brorin-like knockdown [17]. - reference_id: PMID:28448525 supporting_text: However, the role of Brorin in early neural development has not yet been elucidated. - term: id: GO:0030514 label: negative regulation of BMP signaling pathway evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: involved_in supporting_entities: - MGI:MGI:2442987 - MGI:MGI:2444069 - PANTHER:PTN002921765 review: summary: Negative regulation of BMP signaling pathway (IBA, brorin family node). action: ACCEPT reason: Directly supported in zebrafish for this gene. Injected brorin mRNA abolishes Smad1/5/8 phosphorylation, and knockdown raises it in the dorsal brain, without affecting canonical Wnt targets. Mouse Brorin inhibits BMP2/BMP6 activity in cells. This is the core function. PANTHER node PTN002921765 covers both VWC2 and VWC2L (MGI donors Vwc2 and Vwc2l), so the property is ancestral to the brorin family. supported_by: - &id004 reference_id: PMID:28448525 supporting_text: These results indicate that the overexpression of brorin leads to the inactivation of Bmp signaling. - &id002 reference_id: PMID:28448525 supporting_text: In brorin morphants, pSmad was increased in the dorsal region of the brain (MO1, n = 11/11 and MO2, n = 18/18) - &id005 reference_id: PMID:28448525 supporting_text: These results indicate that Brorin inhibits Bmp signaling, but not canonical Wnt signaling. - reference_id: PMID:17400546 supporting_text: 'The protein inhibited the activity of bone morphogenetic protein 2 (BMP2) and BMP6 in mouse preosteoblastic MC3T3-E1 cells.' - term: id: GO:0030900 label: forebrain development evidence_type: IMP original_reference_id: PMID:28448525 qualifier: acts_upstream_of_or_within supporting_entities: - ZFIN:ZDB-MRPHLNO-170613-3 review: summary: brorin morphants (two splice-blocking MOs, mRNA-rescued) lose subpallial identity and forebrain commissures. action: ACCEPT reason: Two non-overlapping splice morpholinos with verified mis-splicing give the same phenotype, and it is rescued by brorin mRNA. The phenotype is explained by raised BMP signalling in the dorsal brain. The MOs are specific for vwc2 over the paralogs (RESULTS.md). There is no mutant yet, so the result carries the usual morpholino caveat. supported_by: - reference_id: PMID:28448525 supporting_text: These results indicate that brorin is required for the development of the subpallial telencephalon. - reference_id: PMID:28448525 supporting_text: We found that the co-injection of brorin RNA with brorin MO1 prevented the development of brain defects caused by brorin MO1 (n = 11/12) (Fig 3G). - *id002 - reference_id: file:DANRE/si_dkey-283b1.7/si_dkey-283b1.7-bioinformatics/RESULTS.md supporting_text: The brorin morpholinos of PMID:28448525 match vwc2 perfectly and have 9 or more mismatches to si:dkey-283b1.7 - term: id: GO:0032281 label: AMPA glutamate receptor complex evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: part_of supporting_entities: - MGI:MGI:2442987 - MGI:MGI:2444069 - PANTHER:PTN002921765 review: summary: AMPA glutamate receptor complex (IBA from mouse Vwc2/Vwc2l proteomics). action: KEEP_AS_NON_CORE reason: Mouse Brorin and Brorin-like co-purify with native AMPA receptors as peripheral extracellular constituents, recruited by Noelins. The PAINT inference is sound for the family, but there is no zebrafish test, and the zebrafish functional data concern early BMP antagonism in forebrain development. Kept as a plausible, non-core location. supported_by: - &id003 reference_id: PMID:37591201 supporting_text: Brorin and Brorin-like have been consistently retrieved in previous anti-GluA APs - reference_id: PMID:37591201 supporting_text: were entirely deprived of both Nrn1 and Brorin (Figure 1D) - term: id: GO:0045202 label: synapse evidence_type: IEA original_reference_id: GO_REF:0000044 qualifier: located_in supporting_entities: - UniProtKB-SubCell:SL-0258 review: summary: Synapse from the UniProt ARBA subcellular location rule. action: KEEP_AS_NON_CORE reason: Follows from the AMPA receptor association of mammalian Brorin. It is plausible in the adult zebrafish brain but untested. supported_by: - *id003 references: - id: GO_REF:0000033 title: Annotation inferences using phylogenetic trees findings: [] - id: GO_REF:0000044 title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt findings: [] - id: PMID:19852960 title: A novel neural-specific BMP antagonist, Brorin-like, of the Chordin family. findings: [] reference_review: relevance: LOW correctness: UNVERIFIED review_notes: Abstract only. The paper concerns Brorin-like (vwc2l); whether it contains vwc2 loss-of-function data cannot be checked. - id: PMID:28448525 title: Brorin is required for neurogenesis, gliogenesis, and commissural axon guidance in the zebrafish forebrain. findings: - statement: Brorin inhibits Bmp but not canonical Wnt signalling in zebrafish. supporting_text: These results indicate that Brorin inhibits Bmp signaling, but not canonical Wnt signaling. - statement: Required for subpallial telencephalon development (MO, rescued). supporting_text: These results indicate that brorin is required for the development of the subpallial telencephalon. reference_review: relevance: HIGH correctness: VERIFIED review_notes: Full text; the only functional study of zebrafish vwc2; morpholino-based with mRNA rescue. - id: PMID:17400546 title: Brorin, a novel secreted bone morphogenetic protein antagonist, promotes neurogenesis in mouse neural precursor cells. findings: [] reference_review: relevance: MEDIUM correctness: VERIFIED review_notes: Abstract; mouse Brorin secreted, inhibits BMP2/6. - id: PMID:37591201 title: A Noelin-organized extracellular network of proteins required for constitutive and context-dependent anchoring of AMPA-receptors. findings: [] reference_review: relevance: LOW correctness: VERIFIED review_notes: Mouse; Brorin as Noelin-recruited AMPAR constituent. Background for the AMPAR/synapse rows. - id: file:DANRE/si_dkey-283b1.7/si_dkey-283b1.7-bioinformatics/RESULTS.md title: si:dkey-283b1.7 / vwc2 protein, synteny, expression and morpholino analyses reference_review: relevance: HIGH correctness: VERIFIED review_notes: Manual audit verified this sidecar supports si:dkey-283b1.7 as a secreted brorin-family protein with an intact cysteine-rich core, confirms published brorin morpholinos are vwc2-specific, and does not establish si:dkey-283b1.7 as a vwc2 TGD ohnolog. findings: - statement: brorin MOs are vwc2-specific. supporting_text: The brorin morpholinos of PMID:28448525 match vwc2 perfectly and have 9 or more mismatches to si:dkey-283b1.7 core_functions: - description: Secreted chordin-like BMP antagonist that restrains BMP/Smad1/5/8 signalling in the developing zebrafish forebrain. It is needed for subpallial patterning, for GABAergic interneuron and oligodendrocyte specification, and for commissural axon guidance. directly_involved_in: - id: GO:0030514 label: negative regulation of BMP signaling pathway locations: - id: GO:0005576 label: extracellular region supported_by: - *id004 - *id002 - *id005 - *id001 suggested_questions: - question: Does Brorin bind BMP ligands directly (and which), or act through another component? No binding assay has been reported for any Brorin family member. - question: Do stable vwc2 mutants reproduce the morphant forebrain phenotypes, and do vwc2 and vwc2l act redundantly in the prethalamus, where both are expressed? - question: Is the IMP to nervous system development from PMID:19852960 based on a vwc2 experiment, or is it vwc2l data attached to vwc2? suggested_experiments: - hypothesis: vwc2 loss-of-function phenotypes reflect raised BMP signalling. description: Generate vwc2 mutants (including an RNA-less allele), score pSmad1/5/8, dlx2a, gad1 and commissures, and test suppression with a BMP receptor inhibitor (e.g. dorsomorphin, DMH1). experiment_type: mutant analysis with pharmacological suppression - hypothesis: si:dkey-283b1.7 does not share the vwc2 forebrain role. description: Compare expression (in situ, retina and brain) and test whether si:dkey-283b1.7 mRNA can rescue vwc2 mutants or dorsalize embryos like brorin mRNA. experiment_type: cross-rescue / overexpression