id: F1Q837 gene_symbol: lhfpl5a product_type: PROTEIN status: COMPLETE taxon: id: NCBITaxon:7955 label: Danio rerio description: lhfpl5a (LHFPL tetraspan subfamily member 5a) is one of two zebrafish co-orthologs of vertebrate LHFPL5 (TMHS), retained from the teleost-specific genome duplication; its paralog is lhfpl5b. It encodes a small four-pass membrane protein of the tetraspan junctional protein superfamily that acts as an accessory subunit of the hair-cell mechanoelectrical transduction (MET) complex. GFP-Lhfpl5a sits at the tips of stereocilia and is enriched at the tallest stereocilia next to the kinocilium; its bundle localization depends on Pcdh15a, Cdh23 and Myo7aa, and Lhfpl5a in turn is needed to bring the tip-link protein Pcdh15a to the hair bundle. It is not needed for bundle targeting of Tmc1 or Tmc2b. lhfpl5a is expressed only in hair cells of the inner ear (maculae and cristae), from 1 dpf into adulthood, and not in the lateral line. The astronaut (tm290d) nonsense mutant has no transduction in any inner-ear sensory patch and is deaf and balance-defective, with splayed hair bundles, while lateral-line hair cells, which use lhfpl5b, work normally. existing_annotations: - term: id: GO:0005886 label: plasma membrane evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: is_active_in supporting_entities: - MGI:MGI:1915382 - MGI:MGI:3057108 - PANTHER:PTN000968268 - RGD:727967 review: summary: Plasma membrane location propagated across the LHFPL family. action: ACCEPT reason: Lhfpl5a is a four-pass membrane protein and GFP-Lhfpl5a is found at stereocilia tips, in the plasma membrane of the hair bundle. Correct but general; the stereocilium tip is proposed as a NEW, more informative location. supported_by: - &id004 reference_id: PMID:32009898 supporting_text: GFP-Lhfpl5a is present at the tips of stereocilia, similar to the localization observed for mouse LHFPL5 (Xiong et al., 2012; Mahendrasingam et al., 2017). - term: id: GO:0007605 label: sensory perception of sound evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: involved_in supporting_entities: - FB:FBgn0262624 - MGI:MGI:1915382 - PANTHER:PTN000968268 review: summary: Sensory perception of sound, from the PANTHER LHFPL5 node (mouse and fly donors). action: ACCEPT reason: lhfpl5a is the copy expressed in the inner ear, and lhfpl5a mutants are profoundly deaf; the GFP-Lhfpl5a transgene rescues the acoustic startle reflex. Lhfpl5a contributes through transduction, captured more specifically by GO:0050974. supported_by: - reference_id: PMID:32009898 supporting_text: Results confirm that lhfpl5atm290d mutants are profoundly deaf, displaying little to no response to acoustic stimuli (p < 0.001 compared to all other genotypes). - &id001 reference_id: PMID:32009898 supporting_text: From these results we conclude that the hair bundle-localized GFP-Lhfpl5a protein is functional and can rescue the behavioral and MET channel defects in lhfpl5atm290d mutants. - term: id: GO:0016020 label: membrane evidence_type: IEA original_reference_id: GO_REF:0000044 qualifier: located_in supporting_entities: - UniProtKB-SubCell:SL-0162 review: summary: Membrane, from UniProt subcellular location (multi-pass membrane protein). action: ACCEPT reason: Correct; less specific than the plasma membrane and stereocilium tip locations. - term: id: GO:0050974 label: detection of mechanical stimulus involved in sensory perception evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: involved_in supporting_entities: - MGI:MGI:1915382 - PANTHER:PTN002647973 - ZFIN:ZDB-GENE-110131-8 review: summary: Detection of mechanical stimulus involved in sensory perception, from the PANTHER LHFPL5 node. action: ACCEPT reason: Core process. lhfpl5a mutants lose transduction in all sensory patches of the ear, and the tagged protein rescues it. The WITH list includes lhfpl5a itself; that is expected, because its own experimental data are among the descendant evidence for the node. supported_by: - &id002 reference_id: PMID:32009898 supporting_text: These three tests confirmed that all sensory patches in the otic capsule are inactive in lhfpl5atm290d mutants. - *id001 - term: id: GO:0050974 label: detection of mechanical stimulus involved in sensory perception evidence_type: IMP original_reference_id: PMID:9491988 qualifier: acts_upstream_of_or_within review: summary: From the original characterization of the astronaut (lhfpl5a) circler mutant, which is defective in balance and hearing. action: ACCEPT reason: 'The 1998 abstract placed astronaut downstream of transduction because lateral-line microphonics were normal. Later work explains this: lateral-line hair cells use lhfpl5b, whereas all inner-ear sensory patches of lhfpl5a mutants lack transduction. The annotated process is therefore correct for lhfpl5a, and the curator''s call is upheld by the later data.' supported_by: - reference_id: PMID:9491988 supporting_text: Mutant astronaut and cosmonaut hair cells have relatively normal microphonics and thus appear to affect events downstream of mechanotransduction. - reference_id: PMID:32009898 supporting_text: lhfpl5atm290d (astronaut/asn) mutants were initially characterized by balance defects, an absence of the acoustic startle reflex, and a lack of brainstem Ca2+ signals after acoustic startle. However, neuromast microphonic potentials were normal (Nicolson et al., 1998). - *id002 - term: id: GO:0060122 label: inner ear receptor cell stereocilium organization evidence_type: IMP original_reference_id: PMID:32009898 qualifier: acts_upstream_of_or_within supporting_entities: - ZFIN:ZDB-GENO-170817-4 review: summary: 'Inner ear receptor cell stereocilium organization: lhfpl5a mutant inner-ear hair bundles are splayed.' action: KEEP_AS_NON_CORE reason: The phenotype is real. The most direct reading is that it follows from the failure to bring Pcdh15a, and so tip links, to the bundle; Lhfpl5a is not known to organize stereocilia by itself. Kept as a correct but non-core consequence of its role in the MET/tip-link complex. supported_by: - reference_id: PMID:32009898 supporting_text: lhfpl5atm290d mutants exhibit splayed hair bundles, with low levels of Pcdh15a staining restricted to the tip of each stereocilium - &id003 reference_id: PMID:28219986 supporting_text: In contrast, EGFP-tagged Pcdh15a remained in the hair cell body of lhfpl5a mutants at all developmental stages, implying that Lhfpl5a is required for transport to the hair bundle. - term: id: GO:0061512 label: protein localization to cilium evidence_type: IMP original_reference_id: PMID:28219986 qualifier: acts_upstream_of_or_within supporting_entities: - ZFIN:ZDB-GENO-171005-7 review: summary: 'Protein localization to cilium: Pcdh15a fails to reach the hair bundle in lhfpl5a mutants.' action: MODIFY reason: 'The observation is sound: tagged and endogenous Pcdh15a stay in the cell body of lhfpl5a mutant hair cells, and the authors infer that Lhfpl5a is needed for transport to the hair bundle. But the destination is the stereocilia, which are actin-based microvillar projections and not cilia; GO:0032420 stereocilium is not a descendant of cilium. GO has no protein-localization-to-stereocilium term, so the nearest correct term is protein localization to plasma membrane (Pcdh15a is a transmembrane tip-link protein that must reach the stereocilia membrane).' proposed_replacement_terms: - id: GO:0072659 label: protein localization to plasma membrane supported_by: - reference_id: PMID:28219986 supporting_text: We next examined the localization pattern of stably expressed Pcdh15a-CD3-GFP in lhfpl5a tm290d mutants and found that Pcdh15a-CD3-EGFP was largely absent in both mature and immature hair bundles, but detectable in hair cell somas - *id003 - term: id: GO:0032426 label: stereocilium tip evidence_type: IDA original_reference_id: PMID:32009898 review: summary: A functional GFP-Lhfpl5a transgene localizes to the tips of stereocilia in inner-ear hair cells. action: NEW reason: Direct localization of a tagged protein shown to rescue the mutant, matching mouse LHFPL5. This is the site of action and is more informative than the plasma membrane rows. supported_by: - *id004 - *id001 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:28219986 title: Functional Analysis of the Transmembrane and Cytoplasmic Domains of Pcdh15a in Zebrafish Hair Cells. findings: [] reference_review: relevance: HIGH correctness: VERIFIED review_notes: Full text. Pcdh15a stays in the cell body in lhfpl5a tm290d mutants. - id: PMID:32009898 title: The lhfpl5 Ohnologs lhfpl5a and lhfpl5b Are Required for Mechanotransduction in Distinct Populations of Sensory Hair Cells in Zebrafish. findings: [] reference_review: relevance: HIGH correctness: VERIFIED review_notes: Full text. Defines the lhfpl5a/lhfpl5b expression split (ear vs lateral line), mutant phenotypes, GFP-Lhfpl5a rescue of lhfpl5b mutants, phylogeny with gar. - id: PMID:9491988 title: 'Genetic analysis of vertebrate sensory hair cell mechanosensation: the zebrafish circler mutants.' findings: [] reference_review: relevance: MEDIUM correctness: VERIFIED review_notes: Abstract only. Original circler screen; astronaut = lhfpl5a tm290d. Its interpretation (downstream of transduction) rested on lateral-line microphonics and is superseded by PMID:32009898. - id: PMID:39484049 title: Molecular specializations underlying phenotypic differences in inner ear hair cells of zebrafish and mice. findings: [] reference_review: relevance: MEDIUM correctness: VERIFIED review_notes: Full text. Adult zebrafish inner-ear hair cells express lhfpl5a but not lhfpl5b. - id: PMID:38194445 title: LHFPL5 is a key element in force transmission from the tip link to the hair cell mechanotransducer channel. findings: [] reference_review: relevance: MEDIUM correctness: VERIFIED review_notes: Full text. Mouse Lhfpl5 knockout; LHFPL5 is a principal component of the gating spring. - id: PMID:40825768 title: prdm1a drives a fate switch between hair cells of different mechanosensory organs. findings: [] reference_review: relevance: LOW correctness: VERIFIED review_notes: Full text. lhfpl5a is among ear genes derepressed in prdm1a mutant lateral-line hair cells. - id: PMID:36598134 title: Single-cell transcriptomic profiling of the zebrafish inner ear reveals molecularly distinct hair cell and supporting cell subtypes. findings: [] reference_review: relevance: LOW correctness: VERIFIED review_notes: Full text. lhfpl5a used as an inner-ear hair-cell marker; lhfpl5b as a lateral-line marker. - id: file:DANRE/lhfpl5a/lhfpl5a-bioinformatics/RESULTS.md title: lhfpl5a / lhfpl5b identity, conserved synteny and expression records reference_review: relevance: HIGH correctness: VERIFIED review_notes: Manual audit verified the sidecar supports a teleost-duplication origin and the reported ear/lateral-line expression split; it notes that the public curated expression mirrors the publications rather than providing an independent functional test. findings: [] core_functions: - description: 'Accessory transmembrane subunit of the inner-ear hair-cell MET complex at stereocilia tips: transmits tip-link tension to the channel (mouse LHFPL5) and is needed to bring Pcdh15a to the hair bundle; required for transduction in all inner-ear sensory patches. Recorded as a contribution to the channel complex''s activity.' contributes_to_molecular_function: id: GO:0140135 label: mechanosensitive monoatomic cation channel activity directly_involved_in: - id: GO:0050974 label: detection of mechanical stimulus involved in sensory perception - id: GO:0007605 label: sensory perception of sound locations: - id: GO:0032426 label: stereocilium tip supported_by: - reference_id: PMID:32009898 supporting_text: 'Here we show that the zebrafish lhfpl5 genes are expressed in discrete populations of hair cells: lhfpl5a expression is restricted to auditory and vestibular hair cells in the inner ear, while lhfpl5b expression is specific to hair cells of the lateral line organ.' - *id002 - *id004 - *id003 - reference_id: PMID:38194445 supporting_text: We conclude that tip-link tension is transmitted to the channel primarily via LHFPL5; residual activation without LHFPL5 may occur by direct interaction between PCDH15 and TMC1. suggested_questions: - question: Does Lhfpl5b rescue lhfpl5a mutant inner-ear hair cells when expressed there? The reverse rescue (Lhfpl5a in lhfpl5b mutant neuromasts) works; the reciprocal would complete the evidence that the two proteins are interchangeable. - question: Is lhfpl5b ever expressed in adult inner-ear hair cells, or is the ear/lateral-line split maintained for life? - question: What protein links Lhfpl5a to Cdh23 and Myo7aa for its localization at kinocilial links, given that no direct LHFPL5-CDH23 interaction has been detected? suggested_experiments: - hypothesis: The lhfpl5a/lhfpl5b split is purely regulatory. description: Express GFP-Lhfpl5b from a pan-hair-cell (myo6b) or lhfpl5a promoter in lhfpl5a tm290d mutants and score acoustic startle, inner-ear microphonics and FM dye uptake. experiment_type: cross-rescue - hypothesis: The cis-regulatory elements that restrict lhfpl5a to the ear and lhfpl5b to the lateral line are ancestral elements partitioned between the copies. description: Test gar lhfpl5 upstream sequences in zebrafish reporter assays for activity in both inner-ear and lateral-line hair cells; compare with the lhfpl5b 2 kb promoter that already drives lateral-line-specific expression. experiment_type: enhancer reporter assay