hbs

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0001745 compound eye morphogenesis	IMP PMID:20599904 Preferential adhesion maintains separation of ommatidia in t...	ACCEPT	Summary: Hbs acts in IRM-mediated preferential adhesion that sorts interommatidial cells and separates ommatidia in the pupal eye. Reason: In the pupal retina Kirre and Rst (in interommatidial cells) bind Hbs and Sns (in primary pigment cells); this heterophilic preferential adhesion is necessary and sufficient to keep ommatidia apart. The adhesion molecule directly does the cell-sorting work, so compound eye morphogenesis is an appropriate (if developmental) process annotation. Supporting Evidence: PMID:20599904 Kirre binds Hbs and Sns in vivo and in vitro. PMID:20599904 Our results indicate mutual preferential adhesion between ommatidia and IOCs mediated by four IRM proteins is both necessary and sufficient to maintain separation of ommatidia.
GO:0001751 compound eye photoreceptor cell differentiation	IMP PMID:22814602 Hibris, a Drosophila nephrin homolog, is required for presen...	KEEP AS NON CORE	Summary: Compound eye photoreceptor cell differentiation. Reason: The IRM proteins act mainly in the later sorting of interommatidial/pigment cells; any effect on photoreceptor differentiation is indirect or minor. Retained as non-core. Supporting Evidence: PMID:20599904 Our results indicate mutual preferential adhesion between ommatidia and IOCs mediated by four IRM proteins is both necessary and sufficient to maintain separation of ommatidia.
GO:0005768 endosome	IDA PMID:22814602 Hibris, a Drosophila nephrin homolog, is required for presen...	KEEP AS NON CORE	Summary: Hbs colocalises with endosomes. Reason: Reflects endocytic trafficking of Hbs, which is regulated by Cindr and endocytosis; not where Hbs acts as an adhesion receptor. Supporting Evidence: PMID:23027549 Disrupting endocytosis similarly led to Rst and Hbs mis-localization
GO:0005886 plasma membrane	IBA GO_REF:0000033	ACCEPT	Summary: Hbs acts at the plasma membrane. Reason: Single-pass transmembrane IgSF adhesion receptor acting at the cell surface; the IBA reflects the conserved Neph/Nephrin family location.
GO:0005911 cell-cell junction	IBA GO_REF:0000033	ACCEPT	Summary: Hbs acts at cell-cell junctions. Reason: IRM proteins localise to sites of cell-cell contact (myoblast fusion sites, the eye adhesive belt, nephrocyte diaphragm); consistent with conserved Neph/Nephrin family location. Supporting Evidence: PMID:26053791 these proteins are apically expressed in the adhesive belt of epithelial cells participating in sense organ development
GO:0005912 adherens junction	IDA PMID:23027549 Interactions between Drosophila IgCAM adhesion receptors and...	ACCEPT	Summary: Hbs localises to adherens junctions in the pupal eye. Reason: Hbs and Rst localise to the apical adhesive belt and depend on Cindr and stable membrane complexes for correct localisation. Supporting Evidence: PMID:23027549 Rst and Hbs localized correctly only when in stable membrane complexes
GO:0007156 homophilic cell-cell adhesion	IGI PMID:19515699 Sns and Kirre, the Drosophila orthologs of Nephrin and Neph1...	MODIFY	Summary: Homophilic cell-cell adhesion (IGI with rst). Reason: The same PMID:19515699 IGI row (hbs with rst) is also annotated to rst, and the two are treated together. Rst is a SYG-1/Neph-like protein that forms (very low-affinity) homodimers, so homophilic adhesion is retained on rst as non-core. Hbs is a SYG-2/Nephrin-like protein: no homophilic complex is detected for SYG-2 orthologs, and Hbs binds the Neph-like Kirre (Dumbfounded) and Rst heterophilically. A genetic interaction between hbs and rst therefore reflects heterophilic Hbs-Rst adhesion, and the term on hbs should be heterophilic cell-cell adhesion (also annotated to hbs by IDA). Proposed replacements: heterophilic cell-cell adhesion Supporting Evidence: PMID:24485456 We did not detect a C. elegans SYG-1 homophilic complex, or homophilic and heterophilic complexes between any SYG-2 PMID:24485456 Minimal complex-forming regions of the homologous Drosophila system were similarly mapped to within the first Ig domain of Rst or Duf, and the first four Ig domains of SNS or Hbs PMID:11684662 Our S2 cell aggregation assays have revealed a heterotypic interaction between Hibris and Dumbfounded, but not between Hibris and Irregular Chiasm-Roughest. PMID:20599904 Kirre binds Hbs and Sns in vivo and in vitro.
GO:0007157 heterophilic cell-cell adhesion	IDA PMID:19270174 The immunoglobulin superfamily member Hbs functions redundan...	ACCEPT	Summary: Hbs mediates heterophilic cell-cell adhesion. Reason: Hbs binds Kirre/Duf heterotypically and functions redundantly with Sns as a ligand for founder-cell Kirre/Rst; core process. Supporting Evidence: PMID:11684662 Our S2 cell aggregation assays have revealed a heterotypic interaction between Hibris and Dumbfounded, but not between Hibris and Irregular Chiasm-Roughest. PMID:19270174 with Kin-of-IrreC (Kirre) and Roughest (Rst) functioning redundantly in the founder cell and Sticks-and-stones (Sns) serving as their ligand in the FCMs
GO:0007220 Notch receptor processing	IMP PMID:22814602 Hibris, a Drosophila nephrin homolog, is required for presen...	KEEP AS NON CORE	Summary: Hbs is required for gamma-secretase-dependent Notch processing. Reason: Hbs interacts with Presenilin and is required for its maturation, so hbs loss reduces Notch S3 cleavage. Hbs does not perform the cleavage; its role appears to be in supporting Presenilin maturation. Retained as non-core pending mechanism. Supporting Evidence: PMID:22814602 Our data suggest that Hbs is required for Psn maturation.
GO:0007520 myoblast fusion	IGI PMID:19270174 The immunoglobulin superfamily member Hbs functions redundan...	ACCEPT	Summary: Hbs participates in myoblast fusion redundantly with Sns. Reason: Hbs is expressed in fusion-competent myoblasts, acts redundantly with Sns in muscle precursor formation, and can partially substitute for Sns; core process. Supporting Evidence: PMID:11684661 Embryos that lack or overexpress hbs show a partial block of myoblast fusion, followed by abnormal muscle morphogenesis. PMID:19270174 demonstrating that sns and hbs function redundantly in the formation of several muscle precursors
GO:0008407 chaeta morphogenesis	IGI PMID:26053791 The Cell Adhesion Molecules Roughest, Hibris, Kin of Irre an...	KEEP AS NON CORE	Summary: Hbs contributes to the regular spacing of sensory bristles in the wing disc/notum. Reason: All four IRM proteins act partially redundantly in sensory organ spacing, likely via cell sorting; a developmental outcome of IRM adhesion, retained as non-core. Supporting Evidence: PMID:26053791 The proteins secure the regular spacing of sensory organs showing partial redundancy and may function in early lateral inhibition events as well as in cell sorting processes.
GO:0009653 anatomical structure morphogenesis	IEA GO_REF:0000117	MODIFY	Summary: Anatomical structure morphogenesis (ARBA). Reason: Very general but true for an adhesion molecule required in eye and bristle morphogenesis (and, through myoblast fusion, muscle formation, captured by separate rows); MODIFY to the specific morphogenesis terms hbs already carries that descend from this term, compound eye morphogenesis (IMP) and chaeta morphogenesis (IGI). Proposed replacements: compound eye morphogenesis chaeta morphogenesis
GO:0016020 membrane	IEA GO_REF:0000044	MODIFY	Summary: Membrane (UniProt subcellular location). Reason: Correct but general for a single-pass type I membrane protein; MODIFY to plasma membrane, which hbs already carries (IBA). Proposed replacements: plasma membrane
GO:0016202 regulation of striated muscle tissue development	IGI PMID:11684661 The immunoglobulin-like protein Hibris functions as a dose-d...	KEEP AS NON CORE	Summary: Regulation of striated muscle tissue development. Reason: Hbs loss or overexpression disrupts myoblast fusion and subsequent muscle morphogenesis; the direct process is myoblast fusion, so this regulation term is a downstream, non-core description. Supporting Evidence: PMID:11684661 Embryos that lack or overexpress hbs show a partial block of myoblast fusion, followed by abnormal muscle morphogenesis.
GO:0016202 regulation of striated muscle tissue development	IMP PMID:11684661 The immunoglobulin-like protein Hibris functions as a dose-d...	KEEP AS NON CORE	Summary: Regulation of striated muscle tissue development. Reason: Hbs loss or overexpression disrupts myoblast fusion and subsequent muscle morphogenesis; the direct process is myoblast fusion, so this regulation term is a downstream, non-core description. Supporting Evidence: PMID:11684661 Embryos that lack or overexpress hbs show a partial block of myoblast fusion, followed by abnormal muscle morphogenesis.
GO:0016202 regulation of striated muscle tissue development	IMP PMID:11684662 Characterization of Drosophila hibris, a gene related to hum...	KEEP AS NON CORE	Summary: Regulation of striated muscle tissue development. Reason: Hbs loss or overexpression disrupts myoblast fusion and subsequent muscle morphogenesis; the direct process is myoblast fusion, so this regulation term is a downstream, non-core description. Supporting Evidence: PMID:11684661 Embryos that lack or overexpress hbs show a partial block of myoblast fusion, followed by abnormal muscle morphogenesis.
GO:0016318 ommatidial rotation	IMP PMID:21441778 Mtl interacts with members of Egfr signaling and cell adhesi...	KEEP AS NON CORE	Summary: Hbs genetically interacts with Mtl in ommatidial rotation. Reason: Based on genetic interaction and phenotypic analysis suggesting a possible role in PCP; tentative and non-core. Supporting Evidence: PMID:21441778 Phenotypic analyses and genetic interaction assays suggest that it may have a role during PCP establishment
GO:0016324 apical plasma membrane	IDA PMID:22814602 Hibris, a Drosophila nephrin homolog, is required for presen...	ACCEPT	Summary: Hbs is localised apically in the adhesive belt of epithelial cells. Reason: Directly observed in the wing disc sensory organ study and the pupal eye; consistent with action at apical cell-cell contacts. Supporting Evidence: PMID:26053791 these proteins are apically expressed in the adhesive belt of epithelial cells participating in sense organ development
GO:0016324 apical plasma membrane	IDA PMID:26053791 The Cell Adhesion Molecules Roughest, Hibris, Kin of Irre an...	ACCEPT	Summary: Hbs is localised apically in the adhesive belt of epithelial cells. Reason: Directly observed in the wing disc sensory organ study and the pupal eye; consistent with action at apical cell-cell contacts. Supporting Evidence: PMID:26053791 these proteins are apically expressed in the adhesive belt of epithelial cells participating in sense organ development
GO:0030154 cell differentiation	IEA GO_REF:0000117	MODIFY	Summary: Cell differentiation (ARBA). Reason: Very general developmental term. hbs carries three specific descendants of it, each with experimental support. They are compound eye photoreceptor cell differentiation (IMP), where Hbs acts indirectly via adhesion and Notch signaling; Malpighian tubule stellate cell differentiation (IMP, IEP); and myoblast fusion (IGI), its defining role. MODIFY to all three. Proposed replacements: compound eye photoreceptor cell differentiation Malpighian tubule stellate cell differentiation myoblast fusion
GO:0042067 establishment of ommatidial planar polarity	IMP PMID:22814602 Hibris, a Drosophila nephrin homolog, is required for presen...	KEEP AS NON CORE	Summary: Establishment of ommatidial planar polarity. Reason: hbs mutants show eye patterning defects associated with Notch signaling; planar polarity effects are indirect. Supporting Evidence: PMID:22814602 Loss of hbs results in classical N-signaling-associated phenotypes in Drosophila, including eye patterning, wing margin, and sensory organ specification defects.
GO:0045747 positive regulation of Notch signaling pathway	IMP PMID:22814602 Hibris, a Drosophila nephrin homolog, is required for presen...	KEEP AS NON CORE	Summary: Hbs promotes Notch signaling. Reason: Supported by Notch-like phenotypes and reduced Notch processing in hbs mutants; mechanism (Presenilin maturation) is indirect relative to its adhesion function. Supporting Evidence: PMID:22814602 Loss of hbs results in classical N-signaling-associated phenotypes in Drosophila, including eye patterning, wing margin, and sensory organ specification defects. PMID:22814602 Our data suggest that Hbs is required for Psn maturation.
GO:0050839 cell adhesion molecule binding	IBA GO_REF:0000033	ACCEPT	Summary: Hbs binds other IRM cell adhesion molecules. Reason: Heterophilic binding between Neph-like (Kirre, Rst) and Nephrin-like (Sns, Hbs) IRM proteins is shown in vivo, in vitro and in the extracellular interactome; this is the core MF of the family and the IBA is sound. Supporting Evidence: PMID:20599904 Kirre binds Hbs and Sns in vivo and in vitro.
GO:0061330 Malpighian tubule stellate cell differentiation	IEP PMID:9927461 Identification of genes controlling malpighian tubule and ot...	UNDECIDED	Summary: Malpighian tubule stellate cell differentiation. Reason: The cited screen paper abstract describes other genes (barr, fas, flb, raw, thr, walrus, drumstick) and does not mention hbs; the full text is not available to verify the IEP/IMP evidence.
GO:0061330 Malpighian tubule stellate cell differentiation	IMP PMID:9927461 Identification of genes controlling malpighian tubule and ot...	UNDECIDED	Summary: Malpighian tubule stellate cell differentiation. Reason: The cited screen paper abstract describes other genes (barr, fas, flb, raw, thr, walrus, drumstick) and does not mention hbs; the full text is not available to verify the IEP/IMP evidence.
GO:0098609 cell-cell adhesion	IBA GO_REF:0000033	ACCEPT	Summary: Hbs mediates cell-cell adhesion. Reason: Core process of the IRM family; the IBA reflects conserved Neph/Nephrin/SYG family function. Supporting Evidence: PMID:20599904 Our results indicate mutual preferential adhesion between ommatidia and IOCs mediated by four IRM proteins is both necessary and sufficient to maintain separation of ommatidia.
GO:0098631 cell adhesion mediator activity	IPI PMID:19270174 The immunoglobulin superfamily member Hbs functions redundan...	ACCEPT	Summary: Hbs has cell adhesion mediator activity, binding Kirre/Duf heterophilically. Reason: The interactor on this IPI row is Sns (FBgn0024189), and the abstract describes a physical association between Hbs and Sns in cis, so this row does not by itself show adhesion between apposed cells and is not specialised to the cell-cell child term. Cell adhesion mediator activity is nonetheless the core MF of Hbs, which acts redundantly with Sns as the fusion-competent myoblast ligand for Kirre/Rst and aggregates heterotypically with Duf-expressing cells; the trans-specific GO:0098632 is kept in core_functions only, as for kirre and rst. Supporting Evidence: PMID:11684662 Our S2 cell aggregation assays have revealed a heterotypic interaction between Hibris and Dumbfounded, but not between Hibris and Irregular Chiasm-Roughest. PMID:20599904 Kirre binds Hbs and Sns in vivo and in vitro.
GO:0160108 animal gross anatomical part developmental process	IEA GO_REF:0000117	MODIFY	Summary: Animal gross anatomical part developmental process (ARBA). Reason: Very general, uninformative grouping term. hbs is pleiotropic, so MODIFY to the specific descendants it already carries with experimental support. They are myoblast fusion (IGI), its defining role in muscle formation; compound eye morphogenesis (IMP); chaeta morphogenesis (IGI); and Malpighian tubule stellate cell differentiation (IMP, IEP). Proposed replacements: myoblast fusion compound eye morphogenesis chaeta morphogenesis Malpighian tubule stellate cell differentiation

Gene Description

Existing Annotations Review

Core Functions

Hbs, displayed on fusion-competent myoblasts and primary pigment cells, binds the Neph-like IRM proteins Kirre and Rst in trans, mediating heterophilic cell-cell adhesion that drives myoblast fusion (redundantly with Sns) and preferential adhesion-based cell sorting in the pupal eye.

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FlyBase

FlyBase gene description for hbs (DROME)

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