Affinage

HAS1

Hyaluronan synthase 1 · UniProt Q92839

Length
577 aa
Mass
64.7 kDa
Annotated
2026-06-10
35 papers in source corpus 15 papers cited in narrative 15 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 7/7 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

HAS1 is a plasma membrane-resident hyaluronan synthase that polymerizes hyaluronan from UDP-GlcNAc and UDP-GlcA, and is alone sufficient for synthesis: reconstituted FLAG-tagged enzyme builds HA in vitro and, with UDP-GlcNAc only, chito-oligosaccharides, with distinct cytoplasmic central-loop residues mediating each sugar-transfer step (PMID:10617644). Among the three HAS isoenzymes it has the highest substrate requirement, being nearly inactive at normal UDP-GlcNAc levels and rescued only when the UDP-GlcNAc pool is raised by glucosamine (PMID:23303191). HAS1 assembles into homo- and heteromeric complexes with HAS2 and HAS3 via an N-terminal domain, and HAS1-containing complexes have the lowest synthetic output, so HAS1 functionally suppresses overall HA synthesis (PMID:25795779). Its enzymatic output requires ER-Golgi-plasma membrane trafficking and produces a CD44-anchored pericellular HA coat that is induced by inflammatory cytokines and high glucose/glucosamine (PMID:24099991). HAS1 is an inducible rather than constitutive gene, transcriptionally activated by IL-1β through an NF-κB- and tyrosine-kinase-dependent route and by TGF-β through an NF-κB-independent, p38 MAPK-dependent route (PMID:13130151, PMID:16258173), and is also a direct STAT3 target (PMID:31930562). In cancer, somatic intronic mutations drive aberrant HAS1 splicing into variants that relocalize and stabilize full-length HAS1, synthesize intracellular HA, and are oncogenic (PMID:19451652, PMID:23301075). In vivo, Has1 loss causes chronic joint inflammation and intra-articular fibrosis without altering bulk ECM HA, indicating a specialized role in regulating inflammatory HA matrices (PMID:26521733).

Mechanistic history

Synthesis pass · year-by-year structured walk · 7 steps
  1. 2000 High

    Establishing whether HAS1 is itself the catalytic synthase resolved whether a single protein performs the full dual-sugar polymerization reaction.

    Evidence Purified recombinant FLAG-HAS1 in vitro enzymatic assay with UDP-sugars plus central-loop site-directed mutagenesis

    PMID:10617644

    Open questions at the time
    • No structure of the catalytic central loop
    • Mechanism of processive chain elongation and membrane translocation not resolved
  2. 2005 High

    Dissecting the upstream signaling inputs showed HAS1 is an inducible gene controlled by two independent transcriptional pathways rather than constitutive expression.

    Evidence Dominant-negative IKK/IκBα adenoviral epistasis, EMSA, RT-PCR, and tyrosine kinase inhibitor dissection in fibroblast-like synoviocytes (also #4, #6, #7, #8)

    PMID:13130151 PMID:15905585 PMID:16258173 PMID:16723203 PMID:18815290

    Open questions at the time
    • Direct NF-κB and TGF-β-responsive elements in the HAS1 promoter not mapped
    • How tyrosine kinase signaling converges on HAS1 transcription unresolved
  3. 2009 Medium

    Characterizing HAS1 splice variants explained how aberrant HAS1 becomes oncogenic by relocalizing and stabilizing the full-length enzyme and producing intracellular HA.

    Evidence Co-transfection imaging, co-IP, pulse-chase turnover, in vitro transformation, and xenograft assays (also #10 minigene splicing)

    PMID:19451652 PMID:23301075

    Open questions at the time
    • Splicing factors driving the intronic-mutation-dependent shift not identified
    • Mechanism by which intracellular HA promotes transformation unknown
  4. 2013 High

    Comparing isoenzyme kinetics and coat retention defined HAS1's distinctive low-activity, substrate-limited, CD44-dependent behavior relative to HAS2/HAS3.

    Evidence Isoenzyme transfection into COS-1 cells with UDP-sugar manipulation, HA ELISA, and CD44-antibody coat displacement (also #2 complex formation)

    PMID:23303191 PMID:24099991 PMID:25795779

    Open questions at the time
    • Physiological conditions under which HAS1 reaches active UDP-GlcNAc thresholds in vivo unclear
    • Structural basis for the suppressive effect of HAS1 heteromers not defined
  5. 2015 Medium

    Genetic ablation in mice separated HAS1's role in inflammatory HA matrices from bulk HA production.

    Evidence Has1-/- mice with cartilage injury, histology, and gene-expression profiling

    PMID:26521733

    Open questions at the time
    • Cellular source of the inflammatory HA matrix not pinpointed
    • Link to IL-17/IL-6 signaling correlative, not mechanistic
  6. 2024 Low

    An Alzheimer's-context study proposed a non-canonical nuclear function for HAS1 regulated by p-tau-dependent monoubiquitination.

    Evidence AβPP/PS1 mouse validation, immunofluorescence, nuclear speckle co-localization, ubiquitination-mutant analysis, and HA ELISA

    PMID:38518923

    Open questions at the time
    • Mechanistic chain (p-tau → ubiquitination → nuclear translocation) requires independent validation
    • Direct transcriptional targets of nuclear HAS1 not established
    • Ubiquitin ligase responsible unidentified
  7. 2026 Medium

    Identification of an AMPK/HAS1 complex implicated HAS1 in hepatic lipid metabolism and metabolic liver disease.

    Evidence Reciprocal Co-IP, SPR, CETSA, and liver-specific Has1 loss-of-function in an HFHC MASH mouse model

    PMID:41695466

    Open questions at the time
    • How AMPK binding modulates HAS1 catalysis or vice versa unresolved
    • Single lab; reciprocal in-cell consequence of complex disruption needs broader validation

Open questions

Synthesis pass · forward-looking unresolved questions
  • How HAS1's enzymatic activity, its suppressive heteromerization, and its non-canonical nuclear/metabolic functions are coordinated in a single cell remains unresolved.
  • No structural model integrating catalysis, complex formation, and trafficking
  • Physiological switch between membrane synthase and nuclear/regulatory roles unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0016740 transferase activity 2 GO:0016787 hydrolase activity 1
Localization
GO:0005794 Golgi apparatus 2 GO:0005886 plasma membrane 2 GO:0005634 nucleus 1 GO:0005829 cytosol 1
Pathway
GO:0140098 catalytic activity, acting on RNA 1
Partners
AMPKCD44HAS2HAS3

Evidence

Reading pass · 15 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2000 HAS1 protein alone is sufficient to synthesize hyaluronan in vitro from UDP-GlcNAc and UDP-GlcA substrates, and when incubated with UDP-GlcNAc alone synthesizes chito-oligosaccharides. Site-directed mutagenesis of the cytoplasmic central loop domain identified specific amino acid residues essential for hyaluronan synthesis (both GlcNAc and GlcA transfer steps) and separate residues exclusively required for GlcA transfer but dispensable for chito-oligosaccharide synthesis, demonstrating that distinct residues mediate each sugar transfer reaction. Recombinant FLAG-tagged HAS1 purification from COS-1 membranes by anti-FLAG affinity chromatography; in vitro enzymatic assay with UDP-sugars; site-directed mutagenesis of cytoplasmic central loop domain; reconstitutive assay conditions The Journal of biological chemistry High 10617644
2013 HAS1 requires substantially higher cellular UDP-GlcNAc concentrations than HAS2 or HAS3 to synthesize hyaluronan. In COS-1 cells with normal UDP-sugar levels, HAS1 is nearly inactive; supplementing with glucosamine (~10-fold increase in UDP-GlcNAc) rescues HAS1-driven hyaluronan synthesis and pericellular coat formation. HAS3 can produce hyaluronan at high speed even at minimal substrate concentrations. Transfection of human HAS1-3 isoenzymes into COS-1 cells; glucosamine and glucose manipulation to alter UDP-sugar pools; measurement of secreted hyaluronan by ELISA; pericellular coat detection by fluorescent hyaluronan-binding probe; HPLC quantification of UDP-sugars The Journal of biological chemistry High 23303191
2015 HAS1, HAS2, and HAS3 form homomeric and heteromeric complexes with each other in live cells, detectable in both the Golgi apparatus and plasma membrane. Interactions occur primarily via an N-terminal ~86 amino acid domain, with additional C-terminal binding sites. HAS1 homomeric complexes have the lowest synthetic activity of all HAS complexes. HAS1 transfection reduces hyaluronan synthesis driven by HAS2 and HAS3, indicating that HAS1-containing heteromers functionally suppress overall HA synthesis. FRET with flow cytometric quantification in live cells; FRET microscopy with acceptor photobleaching; proximity ligation assay (PLA) with endogenous HAS antibodies; C-terminal deletion constructs to map interaction domains The Journal of biological chemistry High 25795779
2013 HAS1-produced hyaluronan coat on MCF-7 cells depends on CD44 for retention at the cell surface (unlike HAS3, whose coat remains attached to HAS3 itself). HAS1 enzymatic activity requires ER-Golgi-plasma membrane trafficking. The HAS1-dependent coat is induced by inflammatory cytokines (IL-1β, TNF-α, TGF-β) and high glucose/glucosamine, revealing context-dependent activation. Immunocytochemistry; transfection of fluorescently tagged HAS1; fluorescent hyaluronan-binding probe for coat detection; displacement with HA hexasaccharides and Hermes1 (anti-CD44) antibody; cytokine and glucose/glucosamine treatments Experimental cell research Medium 24099991
2003 HAS1 mRNA transcription in fibroblast-like synoviocytes is not constitutively active but is specifically induced by TGF-β and IL-1β. Hydrocortisone suppresses IL-1β-induced HAS1 activation by blocking TGF-β-induced phosphorylation of p38 MAPK, a kinase essential for HAS1 induction. HAS2 and HAS3 are constitutively expressed and are also suppressed by glucocorticoids, but via p38-independent mechanisms. RT-PCR for HAS mRNA levels in fibroblast-like synoviocytes; Western blot for p38 MAPK phosphorylation; glucocorticoid (hydrocortisone and dexamethasone) dose-response experiments Rheumatology (Oxford, England) Medium 13130151
2005 IL-1β induces HAS1 transcription via the NF-κB pathway (IκBα degradation and phosphorylation, NF-κB translocation), while TGF-β1 induces HAS1 transcription independently of NF-κB and IKK (TGF-β1 neither caused IκBα degradation nor NF-κB translocation). Overexpression of dominant-negative IKK or IκBα completely abolished IL-1β-induced HAS1 activation but did not affect TGF-β1-induced HAS1 or affect HAS2/HAS3 levels, demonstrating that HAS1 can be activated by two distinct upstream pathways. Adenovirus-mediated gene transfer of mutated IKK and IκBα constructs; RT-PCR for HAS mRNA; Western blot for IκBα phosphorylation/degradation; EMSA for NF-κB translocation The Journal of biological chemistry High 16258173
2005 IL-1β-induced HAS1 transcription in fibroblast-like synoviocytes depends on tyrosine kinase activity (not NF-κB alone): leflunomide specifically blocked IL-1β-induced HAS1 induction and HA synthase activity without affecting constitutive HAS2/HAS3 expression, and two tyrosine kinase inhibitors replicated this selective HAS1 blockade. NF-κB inhibition by leflunomide was ruled out as the mechanism at concentrations that block HAS1. RT-PCR for HAS mRNAs; 14C-glucuronic acid incorporation assay for HAS enzymatic activity; EMSA for NF-κB translocation; tyrosine kinase inhibitor treatment; pyrimidine rescue experiments Journal of immunology Medium 15905585
2006 NF-κB is required for IL-1β-induced HAS1 transcription in type-B synoviocytes: the NF-κB inhibitor PDTC completely abolished IL-1β-induced HAS1 mRNA accumulation and simultaneously blocked IκBα degradation and NF-κB translocation. This confirms HAS1 as an NF-κB-dependent gene in this cell type. RT-PCR for HAS1 mRNA; Western blot for IκBα; EMSA for NF-κB DNA binding; PDTC dose-response treatment in type-B synoviocytes Experimental gerontology Medium 16723203
2008 Epstein-Barr virus and homopolymeric polycytidylic RNA analogs selectively induce HAS1 mRNA expression and HA release in fibroblast-like synoviocytes, while HAS2 and HAS3 remain unchanged. Virus-induced HAS1 activation requires both the p38 MAPK pathway and NF-κB: chemical MAPK inhibitors and overexpression of mutated IKK/IκBα each blocked virus-induced HAS1 transcription. Real-time RT-PCR; HA ELISA; chemical inhibitors of MAPK; adenovirus-mediated overexpression of mutated IKK and IκBα; treatment with live EBV and synthetic RNA polynucleotides The Journal of biological chemistry Medium 18815290
2009 HAS1 splice variants (Va, Vb, Vc) are concentrated in the cytoplasm and Golgi, unlike full-length HAS1 (FL) which is diffusely distributed. HAS1 splice variants synthesize hyaluronan intracellularly. When co-expressed, HAS1 variants physically interact with HAS1-FL (and with each other) to form heteromeric multiprotein assemblies, relocalize HAS1-FL from diffuse cytoskeletal locations to deeper cytoplasmic compartments, and protect HAS1-FL from its otherwise rapid turnover. HAS1-Vc alone is transforming in vitro and tumorigenic in vivo. Co-transfection with fluorescently tagged constructs; immunofluorescence/confocal microscopy for localization; co-immunoprecipitation for protein–protein interactions; pulse-chase for protein turnover; in vitro transformation assay; in vivo xenograft tumor formation The Journal of biological chemistry Medium 19451652
2013 Genetic variations introduced into introns 3 and 4 of a HAS1 minigene promote aberrant pre-mRNA splicing (intron retention and exon skipping) mimicking the pattern seen in multiple myeloma patients. Combining intron 4 deletion with intron 3 mutations shifts splicing from HAS1Vd to HAS1Vb, the clinically significant variant. Most MM patients harbor genetic variations in intron 4, and ~half in intron 3, confirming that intronic mutations drive aberrant HAS1 splicing. HAS1 minigene constructs with introduced deletions/mutations; in vitro splicing assay; sequencing comparison of transfectants vs. MM patient samples PloS one Medium 23301075
2015 Genetic deletion of Has1 in mice leads to chronic joint inflammation and widespread intra-articular fibrosis after cartilage injury, with persistent elevation of genes linked to ECM turnover, IL-17/IL-6 cytokine signaling, and apoptosis at 4 weeks post-injury (when wild-type mice show resolution). Notably, Has1 ablation does not alter gross HA content in ECM, indicating HAS1 has a unique function in regulating inflammatory HA matrices that is distinct from bulk HA production. Has1-/- mouse model; femoral groove cartilage debridement; histology, macroscopic imaging, and gene expression analysis at multiple timepoints; comparison with WT mice Osteoarthritis and cartilage Medium 26521733
2024 Phosphorylated tau (p-tau) mediates AβPP-induced cytosolic-to-nuclear translocation of HAS1. p-tau negatively regulates HAS1 stability, monoubiquitination, and oligomerization, thereby reducing HA synthesis and release. Non-ubiquitinated HAS1 loses enzymatic activity and translocates into the nucleus where it forms nuclear speckles, suggesting a non-canonical nuclear function in gene transcription regulation. Transcriptomic database screening; AβPP/PS1 mouse model validation; immunofluorescence for HAS1 localization; co-localization with nuclear speckle markers (SRRM2); HAS1 ubiquitination mutant analysis; HA ELISA; transcriptomic analysis of DEGs related to non-ubiquitinated HAS1 Matrix biology : journal of the International Society for Matrix Biology Low 38518923
2020 STAT3 binds to the HAS1 promoter and positively regulates HAS1 expression; miR-125a suppresses STAT3 (a direct miR-125a target confirmed by dual-luciferase reporter), thereby reducing HAS1 mRNA and protein levels and suppressing NSCLC cell invasion and migration. Dual-luciferase reporter assay for miR-125a/STAT3 targeting; chromatin immunoprecipitation (ChIP) for STAT3 binding to HAS1 promoter; RT-qPCR and Western blot for STAT3 and HAS1; STAT3 overexpression; functional invasion/migration assays Journal of cellular biochemistry Medium 31930562
2026 HAS1 physically interacts with AMPK to form a complex, and disruption of this AMPK/HAS1 complex by elemicin ameliorates MASH. Loss-of-function of Has1 in liver reduces hepatic steatosis, inflammation, and fibrosis. Has1-mediated lipid metabolism is correlated with MASH severity. Co-immunoprecipitation (Co-IP); surface plasmon resonance (SPR); CETSA (cellular thermal shift assay); liver-specific Has1 inhibition in HFHC diet MASH mouse model; transcriptomic and lipidomic analyses; Western blotting Theranostics Medium 41695466

Source papers

Stage 0 corpus · 35 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2013 Hyaluronan synthases (HAS1-3) in stromal and malignant cells correlate with breast cancer grade and predict patient survival. Breast cancer research and treatment 115 24337597
2000 In vitro synthesis of hyaluronan by a single protein derived from mouse HAS1 gene and characterization of amino acid residues essential for the activity. The Journal of biological chemistry 101 10617644
2013 Hyaluronan synthase 1 (HAS1) requires higher cellular UDP-GlcNAc concentration than HAS2 and HAS3. The Journal of biological chemistry 97 23303191
2012 Hyaluronic acid, HAS1, and HAS2 are significantly upregulated during muscle hypertrophy. American journal of physiology. Cell physiology 63 22785117
2010 Hyaluronan synthases (HAS1-3) and hyaluronidases (HYAL1-2) in the accumulation of hyaluronan in endometrioid endometrial carcinoma. BMC cancer 55 20875124
2005 Intronic splicing of hyaluronan synthase 1 (HAS1): a biologically relevant indicator of poor outcome in multiple myeloma. Blood 54 15731173
2002 Characterization of hyaluronan synthase expression and hyaluronan synthesis in bone marrow mesenchymal progenitor cells: predominant expression of HAS1 mRNA and up-regulated hyaluronan synthesis in bone marrow cells derived from multiple myeloma patients. Blood 53 12239172
2013 Has1 regulates consecutive maturation and processing steps for assembly of 60S ribosomal subunits. Nucleic acids research 51 23788678
2014 Extensive CD44-dependent hyaluronan coats on human bone marrow-derived mesenchymal stem cells produced by hyaluronan synthases HAS1, HAS2 and HAS3. The international journal of biochemistry & cell biology 50 24406795
2009 Expression of hyaluronan synthases (HAS1-3) and hyaluronidases (HYAL1-2) in serous ovarian carcinomas: inverse correlation between HYAL1 and hyaluronan content. BMC cancer 49 19435493
2015 Deficiency of hyaluronan synthase 1 (Has1) results in chronic joint inflammation and widespread intra-articular fibrosis in a murine model of knee joint cartilage damage. Osteoarthritis and cartilage 42 26521733
2007 HAS1 expression in bladder cancer and its relation to urinary HA test. International journal of cancer 41 17230515
2013 Low dose ultraviolet B irradiation increases hyaluronan synthesis in epidermal keratinocytes via sequential induction of hyaluronan synthases Has1-3 mediated by p38 and Ca2+/calmodulin-dependent protein kinase II (CaMKII) signaling. The Journal of biological chemistry 38 23645665
2015 Fluorescence resonance energy transfer (FRET) and proximity ligation assays reveal functionally relevant homo- and heteromeric complexes among hyaluronan synthases HAS1, HAS2, and HAS3. The Journal of biological chemistry 36 25795779
2013 Hyaluronan synthase 1 (HAS1) produces a cytokine-and glucose-inducible, CD44-dependent cell surface coat. Experimental cell research 31 24099991
2004 Light and metabolic regulation of HAS1, HAS1.1 and HAS2, three asparagine synthetase genes in Helianthus annuus. Plant physiology and biochemistry : PPB 30 15246064
2003 Glucocorticoids inhibit induced and non-induced mRNA accumulation of genes encoding hyaluronan synthases (HAS): hydrocortisone inhibits HAS1 activation by blocking the p38 mitogen-activated protein kinase signalling pathway. Rheumatology (Oxford, England) 26 13130151
2009 Aberrant splice variants of HAS1 (Hyaluronan Synthase 1) multimerize with and modulate normally spliced HAS1 protein: a potential mechanism promoting human cancer. The Journal of biological chemistry 24 19451652
2008 Inherited and acquired variations in the hyaluronan synthase 1 (HAS1) gene may contribute to disease progression in multiple myeloma and Waldenstrom macroglobulinemia. Blood 21 18815290
2021 Hyaluronic acid (HA) stimulates the in vitro expression of CD44 proteins but not HAS1 proteins in normal human epidermal keratinocytes (NHEKs) and is HA molecular weight dependent. Journal of cosmetic dermatology 19 33908161
2005 Effects of leflunomide on hyaluronan synthases (HAS): NF-kappa B-independent suppression of IL-1-induced HAS1 transcription by leflunomide. Journal of immunology (Baltimore, Md. : 1950) 19 15905585
2012 Lentiviral-mediated over-expression of hyaluronan synthase-1 (HAS-1) decreases the cellular inflammatory response and results in regenerative wound repair. Cell and tissue research 18 23149717
2006 The NF-kappaB inhibitor pyrrolidine dithiocarbamate blocks IL-1beta induced hyaluronan synthase 1 (HAS1) mRNA transcription, pointing at NF-kappaB dependence of the gene HAS1. Experimental gerontology 17 16723203
2006 The anti-rheumatic gold salt aurothiomalate suppresses interleukin-1beta-induced hyaluronan accumulation by blocking HAS1 transcription and by acting as a COX-2 transcriptional repressor. The Journal of biological chemistry 16 17085450
2005 Adenovirus-mediated gene transfer of mutated IkappaB kinase and IkappaBalpha reveal NF-kappaB-dependent as well as NF-kappaB-independent pathways of HAS1 activation. The Journal of biological chemistry 16 16258173
2020 miR-125a regulates HAS1 and inhibits the proliferation, invasion and metastasis by targeting STAT3 in non-small cell lung cancer cells. Journal of cellular biochemistry 13 31930562
2019 At least two molecules of the RNA helicase Has1 are simultaneously present in pre-ribosomes during ribosome biogenesis. Nucleic acids research 10 31511893
2013 Alteration of introns in a hyaluronan synthase 1 (HAS1) minigene convert Pre-mRNA [corrected] splicing to the aberrant pattern in multiple myeloma (MM): MM patients harbor similar changes. PloS one 8 23301075
2008 Hyaluronan production in synoviocytes as a consequence of viral infections: HAS1 activation by Epstein-Barr virus and synthetic double- and single-stranded viral RNA analogs. The Journal of biological chemistry 7 18400745
2024 AβPP-tau-HAS1 axis trigger HAS1-related nuclear speckles and gene transcription in Alzheimer's disease. Matrix biology : journal of the International Society for Matrix Biology 6 38518923
2014 Altered expression of hyaluronan, HAS1-2, and HYAL1-2 in oral lichen planus. Journal of oral pathology & medicine : official publication of the International Association of Oral Pathologists and the American Academy of Oral Pathology 5 25421996
2025 HAS1high cancer associated fibroblasts located at the tumor invasion front zone promote oral squamous cell carcinoma invasion via ECM remodeling. Journal of experimental & clinical cancer research : CR 4 40813707
2024 Whole-genome sequencing identifies variants in ANK1, LRRN1, HAS1, and other genes and regulatory regions for stroke in type 1 diabetes. Scientific reports 3 38862513
2009 HAS-1 genetic polymorphism in sporadic abdominal aortic aneurysm. Heart international 1 21977277
2026 Therapeutic targeting of the AMPK-Has1 complex formation ameliorates metabolic dysfunction-associated steatohepatitis in mice. Theranostics 0 41695466

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