Affinage

HGFAC

Hepatocyte growth factor activator serine protease · UniProt Q04756

Length
655 aa
Mass
70.7 kDa
Annotated
2026-06-10
35 papers in source corpus 12 papers cited in narrative 12 extracted findings
Cross-family judge vs UniProt: tie faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

HGFAC encodes hepatocyte growth factor activator (HGFA), a trypsin-like serine protease that couples tissue injury to growth-factor activation by proteolytically converting pro-HGF and pro-macrophage-stimulating protein (pro-MSP/RON ligand) into their active forms (PMID:20402763, PMID:25408834). Circulating pro-HGFA is cleaved to its active enzyme by the coagulation protease thrombin (PMID:20402763) and by the kallikrein-related peptidases KLK4 and KLK5, which cut at the physiological Arg407-Ile408 site to yield an enzyme that drives HGF-dependent cell scattering and invasion (PMID:18221492). Crystal structures show that HGFA's substrate-specificity loops (the 99-loop and 220-loop) rest in an enzymatically non-competent conformation in the unliganded state and are remodeled into a catalytically competent, substrate-binding geometry upon ligand engagement, with KD1 side chains occupying the S1/S2/S4 subsites in register with the pro-HGF cleavage sequence—a structural basis for HGFA's narrow substrate selectivity (PMID:15713485, PMID:20402765). On epithelial surfaces HGFA activity is captured and concentrated by membrane-bound HAI-1, which acts as both inhibitor and reservoir and releases active enzyme upon zinc-metalloproteinase-dependent shedding (PMID:11013244); in plasma HGFA is additionally inhibited by protein C inhibitor (SERPINA5/PCI), whose action limits pro-HGF activation and constrains liver regeneration (PMID:20402764). Functionally, injury-released HGFA is sufficient to drive tissue stem and progenitor cells into the GAlert state and to accelerate repair, and HGFA loss impairs mucosal regeneration and macrophage recruitment (PMID:20402763, PMID:28423312). HGFAC transcription is directly controlled by lineage-specific factors—HNF1α in pancreatic β-cells (PMID:22877752) and ChREBP in liver, where HGFAC modulates lipid and glucose homeostasis (PMID:36413406)—and is silenced by DNMT3A-mediated promoter methylation in hepatocellular carcinoma (PMID:38077422).

Mechanistic history

Synthesis pass · year-by-year structured walk · 12 steps
  1. 2000 High

    Established that active HGFA is not simply released free but is captured at the epithelial cell surface, explaining how its pericellular activity is concentrated and regulated.

    Evidence Co-IP and cell-surface binding in engineered CHO and epithelial cells, with metalloproteinase-dependent shedding triggered by phorbol ester/IL-1β

    PMID:11013244

    Open questions at the time
    • Identity of the shedding metalloproteinase not defined
    • Quantitative balance between inhibitory and reservoir roles of HAI-1 in vivo unresolved
  2. 2001 Low

    Linked HGFA-driven HGF activation to a disease context by showing enhanced two-chain HGF generation in colorectal carcinoma versus normal mucosa.

    Evidence Western blot of HGF activation state in tumor vs normal tissue plus cell-surface binding/shedding assays

    PMID:11436357

    Open questions at the time
    • Abstract-level description limits method detail
    • Largely confirms surface-reservoir findings in a new tissue context rather than adding mechanism
    • Causal role of HGFA in tumor progression not directly tested
  3. 2005 High

    Resolved why HGFA is selectively inhibited by HAI-1 and revealed that the enzyme is conformationally latent until ligand binding remodels its active site.

    Evidence X-ray structures of apo HGFA protease domain and the HAI-1B KD1 complex with an inhibition panel across multiple proteases

    PMID:15713485

    Open questions at the time
    • Does not capture the physiological pro-HGF substrate complex directly
    • Dynamics of the loop transition in solution not measured
  4. 2008 High

    Identified KLK4 and KLK5 as physiological activators of pro-HGFA, broadening the proteolytic inputs that switch on HGFA beyond coagulation.

    Evidence In vitro cleavage with N-terminal sequencing of the Arg407-Ile408 site, downstream cell scattering/invasion assays, and HAI-1 inhibition tests

    PMID:18221492

    Open questions at the time
    • Relative in vivo contribution of KLK4/KLK5 versus thrombin not quantified
    • Tissue contexts where each activator dominates unknown
  5. 2010 High

    Provided a structural rationale for HGFA's narrow specificity by superimposing KD1 subsite occupancy onto a pro-HGF-derived substrate mimic.

    Evidence X-ray crystallography of the short-form protease domain compared against a Lys-Gln-Leu-Arg chloromethyl ketone substrate mimic

    PMID:20402765

    Open questions at the time
    • No structure of a genuine pro-HGF/pro-MSP Michaelis complex
    • Determinants of pro-MSP versus pro-HGF preference not separated
  6. 2010 Medium

    Defined plasma protein C inhibitor as a negative regulator of HGFA whose action limits HGF activation and liver regeneration.

    Evidence In vitro complex formation, hPCI-transgenic mouse partial hepatectomy with anti-PCI antibody rescue, and patient plasma ELISA

    PMID:20402764

    Open questions at the time
    • Abstract-level detail limits assessment
    • Stoichiometry and kinetics of HGFA-PCI inhibition not defined
  7. 2010 Medium

    Placed HGFA downstream of the coagulation cascade and demonstrated its requirement for mucosal regeneration and macrophage recruitment in vivo.

    Evidence HGFA-knockout mouse tissue injury and regeneration assays

    PMID:20402763

    Open questions at the time
    • Review-style abstract limits mechanistic detail
    • Relative contributions of HGF versus MSP/RON activation to each phenotype unresolved
  8. 2012 Medium

    Showed that Hgfac is a direct transcriptional target of HNF1α in pancreatic β-cells, connecting its expression to islet transcriptional programs.

    Evidence shRNA knockdown, reporter assay, ChIP, and HNF1α heterozygous mouse islets

    PMID:22877752

    Open questions at the time
    • Functional consequence of β-cell HGFAC expression not established
    • Single lab
  9. 2014 Medium

    Demonstrated that small-molecule active-site inhibition of HGFA blocks pro-HGF/pro-MSP cleavage and dampens c-MET signaling, validating HGFA as a druggable node.

    Evidence Fluorogenic kinetic enzyme assay, native substrate cleavage, and c-MET phosphorylation in MDA-MB-231 cells

    PMID:25408834

    Open questions at the time
    • In vivo efficacy and selectivity not addressed
    • Single lab
  10. 2017 Medium

    Showed that systemic active HGFA is sufficient to drive stem/progenitor cells into the GAlert state and accelerate repair, establishing a systemic injury-to-regeneration signaling role.

    Evidence In vivo systemic HGFA administration to mice with MuSC/FAP activation and tissue repair readouts

    PMID:28423312

    Open questions at the time
    • Endogenous source and kinetics of injury-released HGFA not defined
    • Single lab
  11. 2023 Medium

    Identified ChREBP-driven hepatic HGFAC transcription and linked HGFAC to systemic lipid and glucose homeostasis, extending its biology beyond proteolytic regeneration into metabolism.

    Evidence ChREBP ChIP-Seq plus bidirectional HGFAC gain/loss-of-function mouse models with metabolic phenotyping and PPARγ activity assays

    PMID:36413406

    Open questions at the time
    • Mechanism connecting HGFA proteolysis to PPARγ activation incomplete
    • Whether metabolic effects require HGF/MSP activation untested
  12. 2023 Medium

    Defined an epigenetic silencing axis in which DNMT3A methylates the HGFAC promoter and miR-4270 relieves this silencing, framing HGFAC as a regulated growth-suppressive node in hepatocellular carcinoma.

    Evidence Dual-luciferase, Ago2-RIP, ChIP, methylation-specific PCR, rescue assays, and xenograft model

    PMID:38077422

    Open questions at the time
    • Whether tumor suppression depends on HGFA protease activity not tested
    • Single lab

Open questions

Synthesis pass · forward-looking unresolved questions
  • How the multiple proteolytic activators, surface reservoir, and serpin inhibitors are integrated to set HGFA activity in specific injured tissues in vivo remains unresolved.
  • No structure of a true pro-HGF/pro-MSP cleavage complex
  • Tissue-specific dominance of thrombin vs KLK4/KLK5 activation unknown
  • Mechanistic link between HGFAC and hepatic metabolic regulation incomplete

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140096 catalytic activity, acting on a protein 4 GO:0016787 hydrolase activity 3
Localization
GO:0005576 extracellular region 1 GO:0005886 plasma membrane 1
Pathway
R-HSA-1266738 Developmental Biology 2 R-HSA-109582 Hemostasis 1

Evidence

Reading pass · 12 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2000 Active HGFA forms a specific complex with membrane-bound HAI-1 (but not HAI-2) on the surface of epithelial cells, requiring HGFA enzymatic activity for binding. HAI-1 acts as both an inhibitor and a cell-surface reservoir of active HGFA. The HGFA·HAI-1 complex is released from the cell surface by phorbol ester or IL-1β treatment via a zinc-metalloproteinase-dependent shedding mechanism, generating 58-kDa HAI-1 fragments with reduced inhibitory potency and restoring HGFA activity in the supernatant. Co-immunoprecipitation, CHO cell engineered expression system, cell-surface binding assays, phorbol ester/IL-1β treatment with metalloproteinase inhibitor BB3103 The Journal of biological chemistry High 11013244
2005 Crystal structure of the HGFA protease domain at 2.7 Å revealed an unconventional, non-enzymatically competent conformation of active-site residues in the unliganded state. Co-crystal structure with the first Kunitz domain (KD1) of HAI-1B at 2.6 Å showed that inhibitor binding rearranges the 220-loop and 99-loop into a substrate-binding-competent conformation. KD1 occupies subsites S1, S2, and S4 in a substrate-like manner and is solely responsible for the inhibitory specificity of the HAI-1B extracellular region. HGFA, matriptase, hepsin, plasma kallikrein, and trypsin are potently inhibited by KD1. X-ray crystallography (2.7 Å apo, 2.6 Å complex), serine protease inhibition panel assay Journal of molecular biology High 15713485
2008 Kallikrein-related peptidases KLK4 and KLK5 cleave pro-HGFA at the normal processing site Arg407-Ile408, activating the zymogen. KLK5 required a negatively charged substance (dextran sulfate) for efficient processing whereas KLK4 did not. HGFA activated by these KLKs efficiently converted pro-HGF/SF into active form, leading to cellular scattering and invasion in vitro. Both KLK4 and KLK5 activity on pro-HGFA was strongly inhibited by HAI-1. In vitro protease cleavage assay, N-terminal sequencing of cleavage site, cell scattering/invasion assay, inhibitor (HAI-1) functional assay The FEBS journal High 18221492
2010 Crystal structures of the HGFA short-form (34 kDa protease domain) reveal two conformational states of substrate-specificity-determining loops (220-loop and 99-loop): enzymatically competent and non-competent. In the KD1-HGFA complex structure, KD1 side chains occupying S1, S2, and S4 subsites are virtually superimposable on the P1, P2, and P4 residues of a pro-HGF-derived substrate mimic (Lys-Gln-Leu-Arg chloromethyl ketone), rationalizing HGFA's narrow substrate specificity for pro-HGF and pro-macrophage-stimulating protein. X-ray crystallography, substrate mimic chloromethyl ketone co-crystal comparison The FEBS journal High 20402765
2010 Protein C inhibitor (PCI/SERPINA5) forms a complex with active HGFA and inhibits HGFA-catalyzed activation of pro-HGF. In hPCI-transgenic mice, liver regeneration after partial hepatectomy was significantly impaired compared to wild-type, and this impairment was rescued by anti-human PCI antibody. Plasma HGFA-PCI complex levels were elevated in patients after hepatectomy. In vitro complex formation assay, hPCI-transgenic mouse partial hepatectomy model, antibody rescue experiment, patient plasma ELISA The FEBS journal Medium 20402764
2010 HGFA is a serine protease activated downstream of the blood coagulation cascade (thrombin cleaves pro-HGFA), linking tissue injury to proteolytic activation of pro-HGF. HGFA also activates macrophage-stimulating protein (MSP), the ligand for RON receptor. HGFA-knockout mice show impaired regeneration of severely damaged mucosal epithelium and impaired initial macrophage recruitment in injured tissue in vivo. HGFA-knockout mouse model, in vivo tissue injury/regeneration assays The FEBS journal Medium 20402763
2017 Systemic active HGFA, released in response to injury, is sufficient to induce transition of skeletal muscle stem cells (MuSCs) and fibro-adipogenic progenitors (FAPs) into GAlert state via proteolytic processing/activation of HGF. Administration of active HGFA to animals accelerated stem cell activation and tissue repair. In vivo systemic HGFA administration to mice, stem cell functional activation assays, tissue repair readouts Cell reports Medium 28423312
2012 HNF1α directly regulates transcription of the Hgfac gene in pancreatic β-cells. HNF1α knockdown in MIN6 cells decreased Hgfac expression, and Hgfac expression was also reduced in islets of HNF1α(+/-) mice. Reporter gene analysis and chromatin immunoprecipitation (ChIP) confirmed direct HNF1α binding to the Hgfac promoter. shRNA knockdown, reporter gene assay, chromatin immunoprecipitation (ChIP), HNF1α heterozygous mouse model Biochemical and biophysical research communications Medium 22877752
2023 ChREBP directly regulates HGFAC transcription in liver (identified by ChREBP ChIP-Seq). HGFAC-KO mice exhibited metabolic phenotypes concordant with human loss-of-function variants. In gain- and loss-of-function mouse models, HGFAC enhanced lipid and glucose homeostasis, potentially mediated through activation of hepatic PPARγ activity. ChREBP ChIP-Seq, HGFAC knockout mouse, gain-of-function genetic mouse models, metabolic phenotyping, PPARγ activity assay JCI insight Medium 36413406
2023 DNMT3A methylates the HGFAC promoter, silencing HGFAC expression in hepatocellular carcinoma. miR-4270 targets the 3'UTR of DNMT3A (confirmed by dual-luciferase and Ago2-RIP assays), reducing DNMT3A-mediated methylation of the HGFAC promoter (confirmed by ChIP and methylation-specific PCR), thereby restoring HGFAC expression. HGFAC overexpression counteracted HCC cell growth promoted by miR-4270 inhibition. Dual-luciferase reporter assay, Ago2-RIP, Co-IP, ChIP, methylation-specific PCR, rescue functional assays, xenograft mouse model PeerJ Medium 38077422
2014 Substrate-based ketothiazole inhibitors (e.g., Ac-KRLR-kt) inhibit HGFA enzymatic activity at nM Ki values (as low as 12 nM), block HGFA-mediated conversion of native pro-HGF and pro-MSP, and cause dose-dependent decrease of c-MET signaling in MDA-MB-231 breast cancer cells. Kinetic fluorogenic enzyme assay, native pro-HGF/pro-MSP cleavage assay, c-MET phosphorylation in cancer cells ACS medicinal chemistry letters Medium 25408834
2001 HGFA (factor XII-like serine protease) critically mediates the enhanced activation of HGF/SF observed in colorectal carcinoma tissues compared with normal mucosa, as assessed by the ratio of two-chain (active) to single-chain (latent) HGF. HAI-1 functions both as a cell-surface specific inhibitor of active HGFA and as a reservoir/acceptor on the cell surface, concentrating pericellular HGFA activity. Western blot analysis of HGF activation state in tumor vs. normal tissue, cell-surface binding assays, IL-1β-induced shedding assay Human cell Low 11436357

Source papers

Stage 0 corpus · 35 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2001 hGFAP-cre transgenic mice for manipulation of glial and neuronal function in vivo. Genesis (New York, N.Y. : 2000) 556 11668683
2017 HGFA Is an Injury-Regulated Systemic Factor that Induces the Transition of Stem Cells into GAlert. Cell reports 127 28423312
2005 Synaptic transmission onto hippocampal glial cells with hGFAP promoter activity. Journal of cell science 119 16076898
2000 Hepatocyte growth factor activator inhibitor type 1 is a specific cell surface binding protein of hepatocyte growth factor activator (HGFA) and regulates HGFA activity in the pericellular microenvironment. The Journal of biological chemistry 110 11013244
2010 Hepatocyte growth factor activator (HGFA): pathophysiological functions in vivo. The FEBS journal 65 20402763
2005 Conformational lability in serine protease active sites: structures of hepatocyte growth factor activator (HGFA) alone and with the inhibitory domain from HGFA inhibitor-1B. Journal of molecular biology 61 15713485
2010 Hepatocyte growth factor activator (HGFA): a serine protease that links tissue injury to activation of hepatocyte growth factor. The FEBS journal 60 20402766
2008 Activation of hepatocyte growth factor activator zymogen (pro-HGFA) by human kallikrein 1-related peptidases. The FEBS journal 53 18221492
2016 The hGFAP-driven conditional TSPO knockout is protective in a mouse model of multiple sclerosis. Scientific reports 34 26925573
2014 Inhibitors of HGFA, Matriptase, and Hepsin Serine Proteases: A Nonkinase Strategy to Block Cell Signaling in Cancer. ACS medicinal chemistry letters 34 25408834
2013 Germ-line recombination activity of the widely used hGFAP-Cre and nestin-Cre transgenes. PloS one 30 24349371
2018 Astrocyte Specificity and Coverage of hGFAP-CreERT2 [Tg(GFAP-Cre/ERT2)13Kdmc] Mouse Line in Various Brain Regions. Experimental neurobiology 28 30636902
2015 Structure-based discovery of small molecule hepsin and HGFA protease inhibitors: Evaluation of potency and selectivity derived from distinct binding pockets. Bioorganic & medicinal chemistry 27 25882520
2005 Serum hepatocyte growth factor activator (HGFA) in benign prostatic hyperplasia and prostate cancer. European urology 25 16005141
2023 HGFAC is a ChREBP-regulated hepatokine that enhances glucose and lipid homeostasis. JCI insight 23 36413406
2016 Characterization of pancreatic glucagon-producing tumors and pituitary gland tumors in transgenic mice overexpressing MYCN in hGFAP-positive cells. Oncotarget 21 27769070
2010 Hepatocyte growth factor activator (HGFA): molecular structure and interactions with HGFA inhibitor-1 (HAI-1). The FEBS journal 21 20402765
2001 Pericellular activation of hepatocyte growth factor/scatter factor (HGF/SF) in colorectal carcinomas: roles of HGF activator (HGFA) and HGFA inhibitor type 1 (HAI-1). Human cell 17 11436357
2012 Regional difference of reactive astrogliosis following traumatic brain injury revealed by hGFAP-GFP transgenic mice. Neuroscience letters 16 22343312
2018 Circulating healing (CH) cells expressing BST2 are functionally activated by the injury-regulated systemic factor HGFA. Stem cell research & therapy 15 30409222
2010 Hepatocyte growth factor activator (HGFA): its regulation by protein C inhibitor. The FEBS journal 15 20402764
2002 Roles of hepatocyte growth factor activator (HGFA) and its inhibitor HAI-1 in the regeneration of injured gastrointestinal mucosa. Journal of gastroenterology 12 12572861
2020 hGFAP-Positive Stem Cells Depend on Brg1 for Proper Formation of Cerebral and Cerebellar Structures. Cerebral cortex (New York, N.Y. : 1991) 11 31504276
2019 Piperidine carbamate peptidomimetic inhibitors of the serine proteases HGFA, matriptase and hepsin. MedChemComm 10 31803403
2024 Use of protease substrate specificity screening in the rational design of selective protease inhibitors with unnatural amino acids: Application to HGFA, matriptase, and hepsin. Protein science : a publication of the Protein Society 8 39073183
2012 Identification of hepatocyte growth factor activator (Hgfac) gene as a target of HNF1α in mouse β-cells. Biochemical and biophysical research communications 8 22877752
2000 Hepatocyte growth factor activator (HGF-A) and its zymogen in human placenta. Placenta 8 10985963
2022 Comparison of the Spatiotemporal Expression Patterns of Three Cre Lines, Emx1IRES-Cre, D6-Cre and hGFAP-Cre, Commonly Used in Neocortical Development Research. Cerebral cortex (New York, N.Y. : 1991) 7 34550336
2022 Role of hypoxia on microRNA-dependant regulation of HGFA - HGF - c-Met signalling pathway in human progenitor and mature endothelial cells. The international journal of biochemistry & cell biology 5 36182093
2003 Immunohistochemical localization of hepatocyte growth factor activator (HGFA) in developing mouse liver tissues. Heterogeneous distribution of HGFA protein. The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society 5 12923239
2023 miR-4270 suppresses hepatocellular carcinoma progression by inhibiting DNMT3A-mediated methylation of HGFAC promoter. PeerJ 4 38077422
2024 Serum proteome profiling reveals HGFA as a candidate biomarker for pulmonary arterial hypertension. Respiratory research 3 39609799
2015 Production of hGFAP-DsRed transgenic Guangxi Bama mini-pigs via somatic cell nuclear transfer. Genetics and molecular research : GMR 2 26662422
2025 Properdin, transcortin and HGFAC are novel plasma biomarkers in canine chronic inflammatory enteropathies from active disease to remission. Scientific reports 1 40659816
2018 [Expression and Clinical Significances of HGFA, Matriptase, HAI-1 and HAI-2 in Acute Myeloid Leukemia]. Zhongguo shi yan xue ye xue za zhi 1 30111395

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