Affinage

LSS

Lanosterol synthase · UniProt P48449

Length
732 aa
Mass
83.3 kDa
Annotated
2026-06-10
52 papers in source corpus 9 papers cited in narrative 9 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 4/4 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

LSS (lanosterol synthase) is an endoplasmic reticulum-resident enzyme that catalyzes the cyclization of (S)-2,3-oxidosqualene into lanosterol, the committed cyclization step of the cholesterol biosynthesis pathway (PMID:30723320, PMID:32101538). Tissue-specific loss of LSS enzymatic function is causative for human disease: epidermis-specific Lss knockout in mice produces neonatal lethality from skin barrier failure and adult hypotrichosis, while lens-specific knockout produces cataracts, establishing tissue-autonomous requirements for LSS catalysis (PMID:32101538). A cataract-equivalent G589S knock-in mouse showed that loss of LSS impairs lens secondary fiber differentiation with downregulation of cholesterol synthesis pathways before opacity develops (PMID:34926465), and pharmacological inhibition of oxidosqualene cyclase in hamster and dog reproduced lens, skin, testis, and bone pathology consistent with disrupted local sterol biosynthesis (PMID:16089317). Disease-causing variants act through multiple molecular routes — complete or partial abolition of catalytic activity (PMID:35413293, PMID:36811447), reduced protein expression (PMID:36811447), partial mislocalization out of the ER (PMID:30401459), N-terminal truncation via alternative translation initiation (PMID:35413293), and aberrant splicing from missense or synonymous variants (PMID:39436000) — yet systemic cholesterol levels remain normal in biallelic patients, implicating a tissue-local rather than global sterol deficit (PMID:30723320). Beyond its catalytic role in cholesterol biosynthesis and the genotype-phenotype relationships captured here, no further mechanistic detail has been characterized in the available corpus.

Mechanistic history

Synthesis pass · year-by-year structured walk · 9 steps
  1. 2005 Medium

    Established that inhibiting LSS enzymatic activity in vivo causes tissue-specific pathology, linking the enzyme's catalytic function to organ-level consequences before human disease genetics implicated it.

    Evidence Pharmacological OSC inhibition with three inhibitors in hamster and dog, with histopathology

    PMID:16089317

    Open questions at the time
    • Inhibitor pharmacology does not isolate genetic loss of LSS specifically
    • Did not define which downstream sterol(s) drive each tissue phenotype
  2. 2007 Medium

    Showed that natural Lss alleles range from hypomorphic to null and that strains differ in cholesterol-responsive Lss transcriptional regulation, framing LSS as a tunable node in cholesterol homeostasis.

    Evidence Multi-strain rat genetic screening with allele characterization and transcript analysis

    PMID:17460354

    Open questions at the time
    • Regulatory mechanism of cholesterol-responsive transcription not resolved
    • Rat strain findings not directly translated to human tissue phenotypes
  3. 2018 Medium

    Addressed whether disease variants affect protein localization, showing wild-type LSS is ER-resident while mutants partially mislocalize, identifying mislocalization as one mechanism of loss of function.

    Evidence Immunofluorescence and immunoblotting of wild-type vs. patient-derived mutant LSS in keratinocytes

    PMID:30401459

    Open questions at the time
    • No functional rescue tying mislocalization to loss of catalytic output
    • Single lab; quantitative extent of mislocalization not established
  4. 2019 Medium

    Tested whether LSS disease reflects global cholesterol deficiency and found systemic sterol levels normal in biallelic patients, redirecting the model toward a tissue-local sterol pathway impact.

    Evidence Biochemical sterol profiling in patient blood plus sequencing and minigene splicing assays across families

    PMID:30723320

    Open questions at the time
    • Did not identify the tissue-local metabolite or alternative pathway responsible
    • Blood sterol levels may not reflect tissue-compartment sterol pools
  5. 2020 High

    Demonstrated tissue-autonomous requirements for LSS catalysis by showing distinct phenotypes from epidermis- and lens-specific knockout, and validated the enzymatic block directly in patients via a sebum metabolite biomarker.

    Evidence Tissue-specific conditional Lss knockout mice with distinct phenotypic readouts; sebum (S)-2,3-epoxysqualene/lanosterol ratio in patients

    PMID:32101538

    Open questions at the time
    • Downstream sterol mediators of each tissue phenotype not pinpointed
    • Does not explain why some tissues tolerate loss while others fail
  6. 2021 Medium

    Resolved the developmental timing of LSS-dependent cataract, showing impaired lens fiber differentiation and cholesterol-pathway downregulation precede opacity formation.

    Evidence Homozygous G589S knock-in mouse with histological staging and lens RNA-seq

    PMID:34926465

    Open questions at the time
    • Causal link between differentiation defect and sterol loss not mechanistically proven
    • Single lab; transcriptomic changes are correlative
  7. 2022 Medium

    Confirmed that PPK-congenital alopecia missense variants directly abolish enzymatic activity and identified alternative translation initiation (Met81) producing a truncated protein as a distinct loss-of-function route.

    Evidence In vitro lanosterol-production enzymatic assay across variants; immunoblotting; minigene assay

    PMID:35413293

    Open questions at the time
    • Structural basis of activity loss for each missense residue not defined
    • Single lab biochemical characterization
  8. 2023 Medium

    Distinguished complete from partial loss of function among variants, showing Arg260His abolishes activity with reduced expression while Thr228Ile retains partial activity, refining genotype-to-residual-function relationships.

    Evidence Thin-layer chromatography enzymatic assay and immunoblotting of patient-derived variants in cells

    PMID:36811447

    Open questions at the time
    • Residual-activity thresholds for phenotype severity not quantified
    • Two variants only; single lab
  9. 2024 Medium

    Extended the spectrum of LSS loss-of-function mechanisms by showing a synonymous variant disrupts splicing, demonstrating that non-coding-level changes can cause LSS deficiency.

    Evidence Minigene splicing assay of c.1011G>A

    PMID:39436000

    Open questions at the time
    • Single method (minigene); endogenous splicing in patient tissue not assayed
    • Frameshift product stability and protein consequence not measured

Open questions

Synthesis pass · forward-looking unresolved questions
  • The tissue-local sterol intermediate or signaling consequence that links LSS catalytic loss to lens, hair, and skin barrier failure despite normal systemic cholesterol remains unidentified.
  • No specific downstream metabolite tied to each tissue phenotype
  • No structural model linking variant residues to catalytic mechanism
  • Mechanism of cholesterol-responsive LSS regulation in human tissue unresolved

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0016853 isomerase activity 4
Localization
GO:0005783 endoplasmic reticulum 1
Pathway
R-HSA-1430728 Metabolism 2

Evidence

Reading pass · 9 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2018 Wild-type LSS (lanosterol synthase) protein localizes to the endoplasmic reticulum in keratinocytes, whereas disease-causing mutant LSS proteins show partial mislocalization outside the ER, as demonstrated by immunofluorescence in cells expressing patient-derived mutations. Immunofluorescence and immunoblotting in keratinocytes expressing wild-type vs. mutant LSS American journal of human genetics Medium 30401459
2020 LSS enzymatic activity (conversion of (S)-2,3-epoxysqualene to lanosterol) was confirmed to be blocked in patients with biallelic LSS mutations by measuring the (S)-2,3-epoxysqualene/lanosterol ratio in forehead sebum as a biomarker. Epidermis-specific Lss knockout in mice caused neonatal lethality due to dehydration (skin barrier failure), and tamoxifen-induced adult epidermal knockout caused hypotrichosis. Lens-specific Lss knockout mice developed cataracts, demonstrating tissue-autonomous requirements for LSS enzymatic function. Tissue-specific conditional knockout mouse models (epidermis-specific and lens-specific Lss KO); metabolite ratio measurement in patient sebum PLoS genetics High 32101538
2021 LSS is required for lens development; a mouse model homozygous for the cataract-equivalent Lss G589S mutation showed impaired lens secondary fiber differentiation at E14.5, prior to lens opacity formation at E17.5, with RNA-seq revealing significant downregulation of cholesterol synthesis signaling pathways. Homozygous knock-in mouse model (LssG589S/G589S); histological and RNA-seq analysis of lens development Frontiers in cell and developmental biology Medium 34926465
2022 Three LSS missense variants associated with palmoplantar keratoderma-congenital alopecia (LSS-ΔN80, p.Ile342Ser, p.Gly508Trp) showed markedly decreased lanosterol production in vitro, confirming loss of enzymatic activity. The c.3G>A variant was shown by immunoblotting to produce an N-terminal truncated protein (LSS-ΔN80) via alternative translation initiation at Met81. In vitro enzymatic activity assay (lanosterol quantification); immunoblotting; minigene assay for splice variant The Journal of investigative dermatology Medium 35413293
2023 The LSS Arg260His mutation abolished catalytic activity entirely, while Thr228Ile retained partial enzymatic activity, as assessed by thin layer chromatography of lanosterol production in cells expressing each variant. Immunoblotting showed the Arg260His mutant had markedly reduced expression level compared to wild-type. Thin layer chromatography enzymatic activity assay; immunoblotting in cells expressing patient-derived variants Experimental dermatology Medium 36811447
2007 Functional polymorphisms in the rat Lss gene were identified: Lss(S) is a hypomorphic allele with missense substitutions, Lss(l) is a null allele with deletion/insertion mutations causing loss of function. Different rat strains carrying these alleles show differential ability to regulate Lss transcription in response to cholesterol levels, indicating strain-dependent polymorphisms affect cholesterol homeostasis. Genetic screening across rat strains; characterization of Lss alleles; transcript expression analysis Experimental animals Medium 17460354
2005 Treatment of hamsters and dogs with oxidosqualene cyclase (LSS) inhibitors produced histopathologic lesions in the lens (cataract/lens fiber cell degeneration), skin (hyperkeratosis), testis (atrophy, germ cell depletion), and bone (enchondral ossification failure), demonstrating that inhibition of LSS enzymatic activity in vivo leads to tissue-specific pathology consistent with disrupted sterol biosynthesis. In vivo pharmacological inhibition with three different OSC (LSS) inhibitors in hamster and dog subchronic toxicity studies; histopathological analysis Experimental and toxicologic pathology Medium 16089317
2019 LSS catalyzes the cyclization of (S)-2,3-oxidosqualene into lanosterol in the cholesterol biosynthesis pathway. Quantification of cholesterol and its precursors in patients with biallelic LSS variants showed no noticeable imbalance in systemic cholesterol levels, suggesting an alternative or tissue-local pathway impact rather than global cholesterol deficiency. Biochemical quantification of cholesterol and sterol precursors in patient blood samples; exome/Sanger sequencing; minigene splicing assay Genetics in medicine Medium 30723320
2024 A synonymous LSS variant (c.1011G>A, p.Pro337=) at the edge of exon 9 was confirmed by minigene assay to create a novel splice site, leading to a 46-bp intronic insertion and frameshift, demonstrating that this variant causes loss of LSS function through aberrant splicing rather than amino acid change. Minigene splicing assay The Journal of dermatology Medium 39436000

Source papers

Stage 0 corpus · 52 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2018 Bi-allelic Mutations in LSS, Encoding Lanosterol Synthase, Cause Autosomal-Recessive Hypotrichosis Simplex. American journal of human genetics 61 30401459
2019 Biallelic pathogenic variants in the lanosterol synthase gene LSS involved in the cholesterol biosynthesis cause alopecia with intellectual disability, a rare recessive neuroectodermal syndrome. Genetics in medicine : official journal of the American College of Medical Genetics 51 30723320
2010 The lss supernodulation mutant of Medicago truncatula reduces expression of the SUNN gene. Plant physiology 37 20861425
2020 Metabolic and pathologic profiles of human LSS deficiency recapitulated in mice. PLoS genetics 32 32101538
2017 Congenital cataract with LSS gene mutations: a new case report. Journal of pediatric endocrinology & metabolism : JPEM 32 29016354
2016 The role of HYAL2 in LSS-induced glycocalyx impairment and the PKA-mediated decrease in eNOS-Ser-633 phosphorylation and nitric oxide production. Molecular biology of the cell 30 27798230
2016 Synchronous Bioimaging of Intracellular pH and Chloride Based on LSS Fluorescent Protein. ACS chemical biology 29 27031242
2022 The interaction between polyphyllin I and SQLE protein induces hepatotoxicity through SREBP-2/HMGCR/SQLE/LSS pathway. Journal of pharmaceutical analysis 25 36820075
2015 Investigation into the mechanism of action of the antimicrobial peptides Os and Os-C derived from a tick defensin. Peptides 21 26215047
2022 Biallelic Variants in Lanosterol Synthase (LSS) Cause Palmoplantar Keratoderma-Congenital Alopecia Syndrome Type 2. The Journal of investigative dermatology 20 35413293
2017 The Novel Triazolonaphthalimide Derivative LSS-11 Synergizes the Anti-Proliferative Effect of Paclitaxel via STAT3-Dependent MDR1 and MRP1 Downregulation in Chemoresistant Lung Cancer Cells. Molecules (Basel, Switzerland) 18 29072615
2020 Novel mutations in Chinese hypotrichosis simplex patients associated with LSS gene. The Journal of dermatology 16 33222230
2021 Defect of LSS Disrupts Lens Development in Cataractogenesis. Frontiers in cell and developmental biology 15 34926465
2020 Two cases of severe congenital hypotrichosis caused by compound heterozygous mutations in the LSS gene. The Journal of dermatology 15 33155697
2011 Distribution and expression characteristics of triterpenoids and OSC genes in white birch (Betula platyphylla suk.). Molecular biology reports 14 21647548
2013 Molecular characterization and differential expression studies of an oxidosqualene cyclase (OSC) gene of Brahmi (Bacopa monniera). Physiology and molecular biology of plants : an international journal of functional plant biology 11 24431524
2012 Advantage of Applying OSC to (1)H NMR-Based Metabonomic Data of Celiac Disease. International journal of endocrinology and metabolism 11 23843818
2021 Genome-Wide Identification of OSC Gene Family and Potential Function in the Synthesis of Ursane- and Oleanane-Type Triterpene in Momordica charantia. International journal of molecular sciences 10 35008620
2016 Oxidative Stress Correlates (OSC) in Diabetes Mellitus Patients. Current diabetes reviews 10 25989845
2023 A case of LSS-associated congenital nuclear cataract with hypotrichosis and literature review. American journal of medical genetics. Part A 9 37455568
2020 The Polymorphism rs2968 of LSS Gene Confers Susceptibility to Age-Related Cataract. DNA and cell biology 9 32877255
2019 The dual functionality of antimicrobial peptides Os and Os-C in human leukocytes. Journal of peptide science : an official publication of the European Peptide Society 9 30740816
2022 Expanding the Phenotypic Spectrum of APMR4 Syndrome Caused by a Novel Variant in LSS Gene and Review of Literature. Journal of molecular neuroscience : MN 8 36251212
2005 Histopathologic findings after treatment with different oxidosqualene cyclase (OSC) inhibitors in hamsters and dogs. Experimental and toxicologic pathology : official journal of the Gesellschaft fur Toxikologische Pathologie 8 16089317
2023 Biallelic mutations in LSS in autosomal-recessive mutilating palmoplantar keratoderma. Experimental dermatology 7 36811447
2023 The Identification of SQS/SQE/OSC Gene Families in Regulating the Biosynthesis of Triterpenes in Potentilla anserina. Molecules (Basel, Switzerland) 7 36985754
2023 A case of congenital cataracts with hypotrichosis caused by compound heterozygous variants in the LSS gene. Molecular genetics & genomic medicine 7 37947113
2022 Systematic Identification and Analysis of OSC Gene Family of Rosa rugosa Thunb. International journal of molecular sciences 7 36430363
2019 Unravelling triterpene biosynthesis through functional characterization of an oxidosqualene cyclase (OSC) from Cleome arabica L. Plant physiology and biochemistry : PPB 7 31561200
2007 Functional polymorphisms of the Lss and Fdft1 genes in laboratory rats. Experimental animals 6 17460354
2005 Influence of high concentrations of mineral salts on production process and NaCl accumulation by Salicornia europaea plants as a constituent of the LSS phototroph link. Advances in space research : the official journal of the Committee on Space Research (COSPAR) 6 16175688
2022 Oxidative stress coping capacity (OSC) value: Development and validation of an in vitro measurement method for blood plasma using electron paramagnetic resonance spectroscopy (EPR) and vitamin C. Free radical biology & medicine 5 36442587
2021 High Expression of Lysophosphatidic Acid Induces Nerve Injury in LSS Patients via AKT Mediated NF-κB p65 Pathway. Frontiers in pharmacology 5 33815123
2011 A simple method for extracting DNA from Cryptosporidium oocysts using the anionic surfactant LSS. New biotechnology 5 21924387
2023 A novel homozygous mutation in LSS gene possibly causes hypotrichosis simplex in two siblings of a Tibetan family from the western Sichuan province of China. Frontiers in physiology 4 36685177
2024 Clinical and genetic analyses of APMR4 syndrome caused by novel biallelic LSS variants. Frontiers in neuroscience 3 38800572
2023 Non-syndromic hypotrichosis: A report of two novel variants in the LSS gene. Pediatric dermatology 2 37029088
2023 Secondary Metabolites from Dendrobium nobile and Their Activities Induce Metabolites Apoptosis in OSC-19 Cells. Molecules (Basel, Switzerland) 2 37110660
2024 Genome-wide identification and expression analysis of the OSC gene family in Platycodon grandiflorus. PeerJ 1 39677956
2024 Genome-Wide Identification and Characterization of OSC Gene Family in Gynostemma pentaphyllum (Cucurbitaceae). Life (Basel, Switzerland) 1 39768308
2023 Crystal structure of Leptospira LSS_01692 reveals a dimeric structure and induces inflammatory responses through Toll-like receptor 2-dependent NF-κB and MAPK signal transduction pathways. The FEBS journal 1 37243454
2020 Whole genome bisulfite sequencing of Medicago truncatula A17 wild type and lss mutants. BMC research notes 1 32234059
2009 [Study of quantitative analysis of protein in barley using OSC-PLS algorithm]. Guang pu xue yu guang pu fen xi = Guang pu 1 19798953
2026 [Effect of Trifolium repens extract on OSC-4 cell proliferation, apoptosis and NLRP3/PRKD3 protein level]. Shanghai kou qiang yi xue = Shanghai journal of stomatology 0 41928531
2025 A novel LSS variant leading to hypotrichosis with pseudoainhum. The Journal of dermatology 0 40237410
2025 Congenital hypotrichosis caused by compound heterozygous variants in the LSS gene in a Chinese patient with strabismus: case report. Frontiers in pediatrics 0 40364812
2025 Hypotrichosis 14: novel variants of the LSS gene in five Chinese families and insights from literature review. Human genomics 0 40696433
2024 Minor Hydroxylated Triterpenoids Produced in Engineered Yeast by the Enzymes OSC and CYP716s from the Plant Enkianthus chinensis and Their Anti-Inflammatory and Hepatoprotective Activities. Journal of natural products 0 38600636
2024 ABD-3, the confluence of powerful antibacterial modalities: ABDs delivering and expressing lss, the gene encoding lysostaphin. Antimicrobial agents and chemotherapy 0 39072634
2024 [Method of Inducible Knockdown of Essential Genes in OSC Cell Culture of Drosophila melanogaster]. Molekuliarnaia biologiia 0 39355887
2024 Biallelic pathogenic variants in the LSS gene cause congenital alopecia-cataract syndrome. The Journal of dermatology 0 39436000
2004 [Malignant transformation of a human oral squamous cell carcinoma cell strain OSC-19 by EBV encoded small RNAs]. Lin chuang er bi yan hou ke za zhi = Journal of clinical otorhinolaryngology 0 15715415

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