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PKD1L1

Polycystin-1-like protein 1 · UniProt Q8TDX9

Length
2849 aa
Mass
315.4 kDa
Annotated
2026-06-10
12 papers in source corpus 9 papers cited in narrative 9 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 5/5 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

PKD1L1 encodes a large polycystin-1-like transmembrane protein, with two Ig-like PKD domains, a REJ domain, a GPS motif, a LH2/PLAT domain, a coiled-coil domain, and multiple putative transmembrane segments, expressed in testis and heart (PMID:11863367). Its central characterized function is in establishing vertebrate left-right asymmetry: PKD1L1 physically interacts with and co-localizes with PKD2 (polycystin-2) in node/Kupffer's vesicle cilia, where the PKD1L1-PKD2 complex acts downstream of nodal flow to trigger asymmetric gene expression, and loss of PKD1L1 phenocopies loss of PKD2 (PMID:21307093, PMID:21307098). This sensory function operates within motile cilia that carry the complex, rather than a separate immotile population (PMID:21307098), with PKD1L1 loss producing laterality defects without the motile-cilia comorbidities seen in classic ciliopathies (PMID:20080492). Beyond laterality, PKD1L1 supports primary ciliogenesis on cholangiocytes and acts upstream of ciliary Hedgehog/GLI1 signalling in bile duct homeostasis; its loss reduces cholangiocyte cilia and Hedgehog-pathway gene expression while driving fibrosis and abnormal duct morphogenesis, a phenotype recapitulated by GLI1 inhibition (PMID:38460793, PMID:36645229, PMID:37675454). Bi-allelic loss-of-function PKD1L1 mutations in humans cause laterality defects with complex congenital heart malformation, and a missense substitution disrupting a conserved GPS-motif cysteine establishes the GPS motif as critical for protein function (PMID:27616478).

Mechanistic history

Synthesis pass · year-by-year structured walk · 7 steps
  1. 2002 Medium

    Established the molecular identity of PKD1L1 as a polycystin-1-like multidomain transmembrane protein, defining the domain architecture that frames all later mechanistic work.

    Evidence Full-length cDNA sequencing from human testis with expression mapping and FISH chromosomal localization

    PMID:11863367

    Open questions at the time
    • Domain architecture inferred from sequence homology, not structurally resolved
    • No functional assay for any domain
    • Cellular and ciliary localization not yet examined
  2. 2010 Medium

    Showed that PKD1L1 loss causes laterality defects via sensory (immotile) cilium dysfunction rather than motile-cilia failure, distinguishing it from classic motile ciliopathies.

    Evidence Constitutive Pkd1l1-knockout mouse with phenotype battery and comparative pathology against motile-cilia mutants

    PMID:20080492

    Open questions at the time
    • Molecular partner mediating the sensory function not identified here
    • Single lab
    • Direct demonstration of ciliary localization not provided
  3. 2011 High

    Defined the core mechanism: PKD1L1 forms a ciliary complex with PKD2 that acts downstream of nodal flow as the left-right symmetry-breaking sensor, resolving how the protein transduces flow into asymmetric gene expression.

    Evidence Co-immunoprecipitation, ciliary co-localization, and genetic epistasis via matched Pkd1l1/Pkd2 mutant phenocopying in mouse, plus positional cloning of the medaka abc mutant with interaction and motility analysis

    PMID:21307093 PMID:21307098

    Open questions at the time
    • Whether the complex senses mechanical flow versus a chemical signal not resolved
    • Channel activity / ion conductance of the complex not directly measured
    • Stoichiometry and structure of the PKD1L1-PKD2 complex unknown
  4. 2016 Medium

    Connected PKD1L1 to human disease and pinpointed the GPS motif as functionally essential, showing that bi-allelic loss of function causes heterotaxy and congenital heart disease.

    Evidence Whole-exome sequencing of two families with molecular modelling of a GPS-motif disulfide bridge

    PMID:27616478

    Open questions at the time
    • GPS disruption not reconstituted in vitro
    • Effect of GPS mutation on PKD2 interaction not tested
    • Mechanism linking GPS folding to ciliary function inferred from modelling
  5. 2023 Medium

    Extended PKD1L1 function beyond laterality to biliary tree development, establishing a cell-autonomous role in cholangiocyte ciliogenesis and duct morphogenesis conserved across species.

    Evidence Liver-specific conditional Pkd1l1 knockout mice (EM, RNA-seq, ligation challenge) and CRISPR pkd1l1 null zebrafish with biliary functional assay

    PMID:36645229 PMID:37675454

    Open questions at the time
    • Molecular signalling pathway downstream of biliary cilia not yet identified in these studies
    • Whether PKD2 partnership operates in cholangiocytes untested
    • Single lab per model
  6. 2024 Medium

    Placed PKD1L1 upstream of ciliary Hedgehog/GLI1 signalling in bile duct homeostasis, providing a pathway mechanism for the biliary phenotype.

    Evidence Constitutive and conditional Pkd1l1 knockout mice with cholangiography, gene expression profiling, and GLI1-inhibitor (Gant61) pharmacological epistasis

    PMID:38460793

    Open questions at the time
    • Direct molecular link between PKD1L1 and Hedgehog component activation not defined
    • Whether the effect is solely via cilium loss or a direct signalling role unresolved
    • Single lab
  7. 2024 Low

    Implicated PKD1L1 in lymphatic vessel development, broadening its physiological roles, with variant-specific effects on protein localization.

    Evidence Exome sequencing of congenital chylothorax cases with PKD1L1 localization assays and lymphatic-vessel immunofluorescence in mutant mouse embryos

    PMID:38247840

    Open questions at the time
    • No functional reconstitution or pathway placement for the lymphatic role
    • Mechanism connecting PKD1L1 to lymphatic morphogenesis unknown
    • Single lab, descriptive phenotyping

Open questions

Synthesis pass · forward-looking unresolved questions
  • How the PKD1L1-PKD2 complex physically transduces nodal flow into intracellular signalling, and whether its biliary and lymphatic roles depend on the same complex and channel mechanism, remains unresolved.
  • No structure of the PKD1L1-PKD2 complex
  • Ion-conductance / mechanosensory activity not directly measured
  • Tissue-specific partners for biliary and lymphatic functions unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140299 molecular sensor activity 2
Localization
GO:0005929 cilium 4
Pathway
R-HSA-1266738 Developmental Biology 4 R-HSA-162582 Signal Transduction 1
Partners
Complex memberships
PKD1L1-PKD2 polycystin complex

Evidence

Reading pass · 9 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2011 Pkd1l1 physically interacts with Pkd2 (co-immunoprecipitation), co-localises with Pkd2 in the cilium of mouse node cells, and both proteins act downstream of nodal flow to establish left-right asymmetry; loss of Pkd1l1 phenocopies loss of Pkd2, with failure to activate asymmetric gene expression at the node and in the lateral plate mesoderm, and right isomerism of the lungs, despite normal node/cilia morphology and motility. Biochemical co-immunoprecipitation, cell biological co-localisation in cilia, phenotypic comparison of Pkd1l1 and Pkd2 point mutants (mouse genetics) Development (Cambridge, England) High 21307093
2011 In medaka (zebrafish-related model), pkd1l1 is expressed exclusively in Kupffer's vesicle (KV); Pkd1l1 and Pkd2 interact and interdependently co-localise at motile KV cilia; all KV cilia contain Pkd1l1, Pkd2, and left-right dynein and are motile, indicating Pkd1l1-Pkd2 complexes function as the nodal flow sensor within motile cilia rather than in a separate immotile sensory population. Genetic mapping of medaka left-right mutant abecobe (abc) to pkd1l1; immunofluorescence co-localisation; interaction assay; ciliary motility analysis Development (Cambridge, England) High 21307098
2010 Pkd1l1-knockout mice develop situs inversus without hydrocephalus, sinusitis, or male infertility, indicating that Pkd1l1 loss causes laterality defects through dysfunction of mechanosensory (immotile) cilia rather than motile cilia, consistent with a sensory role analogous to Pkd1 in renal primary cilia. Constitutive Pkd1l1 knockout mouse; phenotype battery screening; comparative pathology with Dpcd/Poll and Nme7 knockouts that have motile-cilia defects Veterinary pathology Medium 20080492
2002 PKD1L1 encodes a 2849-amino-acid polycystin-1-like protein with two Ig-like PKD domains, a REJ domain, a GPS motif, a LH2/PLAT domain, a coiled-coil domain, and 11 putative transmembrane domains; it is expressed in human testis, fetal and adult heart, and in mouse Leydig cells of the testis. Full-length cDNA sequencing from human testis; dot-blot and RT-PCR expression analysis; in situ hybridization; FISH chromosomal mapping Genomics Medium 11863367
2016 Bi-allelic loss-of-function mutations in human PKD1L1 cause laterality defects (situs inversus totalis and heterotaxy with complex congenital heart malformations); a missense mutation p.Cys1691Ser disrupts a conserved cysteine in the GPS motif predicted to be required for a disulfide bridge essential for proper GPS-motif folding, establishing the GPS motif as functionally critical. Whole-exome sequencing of two unrelated families; molecular modelling of GPS motif disulfide bridge; splice-site mutation prediction American journal of human genetics Medium 27616478
2024 Pkd1l1 deficiency in biliary epithelial cells reduces primary cilia on cholangiocytes, decreases expression of ciliary Hedgehog-pathway signalling genes (Gli1, Gli2, Ptch1, Ptch2), and increases fibrosis/ECM-remodelling genes (Tgfα, Cdkn1a, Hb-egf, Fgfr3, Pdgfc, Mmp12, Mmp15), leading to bile duct hypertrophy, fibrosis, and delayed biliary drainage; pharmacological inhibition of GLI1 with Gant61 recapitulates the Pkd1l1-deficient biliary phenotype, placing Pkd1l1 upstream of ciliary Hedgehog/GLI1 signalling in bile duct homeostasis. Constitutive and conditional Pkd1l1 knockout mice; cholangiography; DDC dietary challenge; immunofluorescence for primary cilia; gene expression analysis; GLI1 inhibitor (Gant61) pharmacological epistasis Journal of hepatology Medium 38460793
2023 Liver-specific (hepatoblast) deletion of Pkd1l1 causes reduced primary cilia on cholangiocytes, delayed biliary maturation, progressive cholangiocyte proliferation, peribiliary fibroinflammation, and arterial hypertrophy, demonstrating a cell-autonomous role for Pkd1l1 in intrahepatic biliary ciliogenesis and duct morphogenesis. CRISPR-based conditional loxP Pkd1l1 allele crossed with AFP-Cre for liver-specific knockout; immunofluorescence; electron microscopy; RNA sequencing; bile duct ligation challenge Hepatology (Baltimore, Md.) Medium 36645229
2023 Loss of pkd1l1 in zebrafish causes left-right patterning defects and reduces biliary epithelial cell number and intrahepatic biliary network density, demonstrating a conserved role for Pkd1l1 in biliary tree development beyond laterality. CRISPR/Cas9-generated pkd1l1hsc117 zebrafish allele; fluorescent biliary functional assay (PED6 accumulation); immunofluorescence quantification of biliary epithelial cells Disease models & mechanisms Medium 37675454
2024 PKD1L1 missense variants implicated in congenital chylothorax cause protein dysfunction without mislocalization, whereas a loss-of-function frameshift variant causes protein mislocalization; Pkd1l1 mutant mouse embryos display pleural effusion and altered lymphatic vessel morphology at E14.5, identifying a role for PKD1L1 in lymphatic vessel development. Exome sequencing; immunofluorescence assessment of PKD1L1 protein localization for identified variants; immunofluorescence staining of lymphatic vessels in Pkd1l1 mutant mouse embryos at E14.5 Cells Low 38247840

Source papers

Stage 0 corpus · 12 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2011 Pkd1l1 establishes left-right asymmetry and physically interacts with Pkd2. Development (Cambridge, England) 145 21307093
2011 Pkd1l1 complexes with Pkd2 on motile cilia and functions to establish the left-right axis. Development (Cambridge, England) 105 21307098
2010 Situs inversus in Dpcd/Poll-/-, Nme7-/- , and Pkd1l1-/- mice. Veterinary pathology 73 20080492
2016 Bi-allelic Mutations in PKD1L1 Are Associated with Laterality Defects in Humans. American journal of human genetics 61 27616478
2002 The sequence, expression, and chromosomal localization of a novel polycystic kidney disease 1-like gene, PKD1L1, in human. Genomics 40 11863367
2024 Pkd1l1-deficiency drives biliary atresia through ciliary dysfunction in biliary epithelial cells. Journal of hepatology 20 38460793
2023 Liver-restricted deletion of the biliary atresia candidate gene Pkd1l1 causes bile duct dysmorphogenesis and ciliopathy. Hepatology (Baltimore, Md.) 20 36645229
2019 Compound heterozygous Pkd1l1 variants in a family with two fetuses affected by heterotaxy and complex Chd. European journal of medical genetics 12 31026592
2021 Hydrops fetalis in PKD1L1-related heterotaxy: Report of two foetuses and expanding the phenotypic and molecular spectrum. Annals of human genetics 6 33655537
2023 Loss of zebrafish pkd1l1 causes biliary defects that have implications for biliary atresia splenic malformation. Disease models & mechanisms 5 37675454
2023 Traveling to the left: A story of PKD1L1-containing vesicles. Developmental cell 1 37607472
2024 PKD1L1 Is Involved in Congenital Chylothorax. Cells 0 38247840

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