HSD17B11

HSD17B11 is an endoplasmic reticulum-anchored short-chain dehydrogenase/reductase that oxidizes 17β-hydroxysteroids and contributes to cellular lipid homeostasis (PMID:12697717, PMID:26472732). Functioning as a NAD+-dependent enzyme, it converts 5α-androstane-3α,17β-diol to androsterone and oxidizes β-estradiol, testosterone, and additional steroid and retinoid substrates with defined kinetics, acting on 17β-hydroxysteroids but not glucocorticoids (PMID:12697717, PMID:26472732). The protein is an integral ER membrane protein of cytosolic orientation and also localizes to lipid droplets in steroidogenic cells, positioning these organelles as sites of steroid metabolism (PMID:26472732, PMID:30358111). On lipid droplets, HSD17B11 physically interacts with the anti-ferroptotic protein FSP1 and is required to maintain FSP1 lipid droplet association and total FSP1 abundance, such that its loss increases sensitivity to lipid oxidative stress (PMID:42239065). Independently, HSD17B11 bioactivates lipidic alkynylcarbinol prodrugs by oxidizing the carbinol center to reactive ynone electrophiles that covalently modify proteins, triggering ER stress, unfolded protein response, proteasome inhibition, and apoptosis, a property exploited for selective cytotoxicity in cancer cells expressing the enzyme (PMID:35535493, PMID:37816126, PMID:33021790). Its expression is controlled at the transcriptional level by Sp1 and C/EBPα binding the proximal promoter (PMID:21549806) and post-transcriptionally by m6A modification through FTO and the reader YTHDF1 (PMID:35568876).

1. 1998 Medium

   Established HSD17B11 as a distinct member of the short-chain alcohol dehydrogenase superfamily acting on 17β-hydroxysteroids, defining its enzyme class and substrate selectivity.

   Evidence Heterologous expression in CHO cells with a substrate metabolism panel and Northern blot

   PMID:9888557

   Open questions at the time

   • Endogenous oxidoreductase activity confounded substrate assignment
   • No kinetic parameters or product identification
   • Physiological substrate not established
2. 2003 High

   Defined a specific androgen-metabolizing reaction and its hormonal regulation, anchoring HSD17B11 in steroidogenesis.

   Evidence Enzyme activity assay in transfected cells with defined substrate/product, Northern blot, immunohistochemistry, and promoter analysis

   PMID:12697717

   Open questions at the time

   • Direction of catalysis in vivo (oxidative vs reductive) not resolved
   • Tissue-specific physiological role not defined
3. 2010 Medium

   Linked HSD17B11 expression to C/EBP transcription factors but showed the induction is not mediated by proximal CCAAT boxes, refining the regulatory model.

   Evidence Ectopic C/EBP isoform expression with gene reporter and promoter analysis in HepG2 cells

   PMID:20638476

   Open questions at the time

   • Actual cis-element mediating C/EBP induction not identified
   • Single hepatocarcinoma cell context
4. 2011 High

   Mapped direct transcription-factor occupancy of the HSD17B11 promoter, establishing Sp1 and C/EBPα as drivers of its expression in prostate cancer.

   Evidence Promoter-reporter constructs with site-directed mutagenesis, DAPA, and ChIP

   PMID:21549806

   Open questions at the time

   • Upstream signals controlling Sp1/C/EBPα recruitment unknown
   • Relevance to non-prostate tissues not tested
5. 2015 High

   Reconstituted catalysis with recombinant enzyme and defined membrane topology, establishing HSD17B11 as a cytosolically oriented ER enzyme with measured substrate kinetics.

   Evidence Recombinant protein expression, in vitro enzyme kinetics, and membrane topology determination

   PMID:26472732

   Open questions at the time

   • High Km for testosterone questions physiological substrate
   • Cofactor preference in vivo not addressed
6. 2018 Medium

   Localized HSD17B11 to lipid droplets across multiple species, implicating these organelles as steroid metabolism sites and expanding its subcellular context beyond the ER.

   Evidence Lipid droplet proteomics by mass spectrometry, Western blot of fractionated LDs, and subcellular imaging

   PMID:30358111

   Open questions at the time

   • Mechanism of LD targeting not defined
   • Functional consequence of LD localization not tested in this study
7. 2020 Medium

   Identified HSD17B11 in an unbiased screen as the determinant of dehydrofalcarinol cytotoxicity, revealing a prodrug-bioactivation function.

   Evidence Genome-wide CRISPR-Cas9 knockout screen with cytotoxicity readout in TNBC cells

   PMID:33021790

   Open questions at the time

   • Bioactivation mechanism not resolved in this study
   • Limited mechanistic follow-up
8. 2022 High

   Established the chemical mechanism of prodrug bioactivation, showing HSD17B11 oxidizes alkynylcarbinols to protein-reactive ynones that trigger ER stress and apoptosis.

   Evidence Haploid genetic screen, in vitro enzymatic oxidation, mass spectrometry of adducts, and ER stress/UPS functional assays

   PMID:35535493

   Open questions at the time

   • Endogenous physiological substrate distinct from prodrugs not identified
   • Range of modified protein targets incompletely defined
9. 2022 Medium

   Revealed post-transcriptional control of HSD17B11 by m6A, with FTO promoting and YTHDF1 repressing its expression, and linked elevated HSD17B11 to lipid droplet formation.

   Evidence meRIP-seq, siRNA knockdown, overexpression, and lipid droplet staining in esophageal cancer cells

   PMID:35568876

   Open questions at the time

   • Mechanistic basis for LD induction by HSD17B11 not defined
   • Single cancer context
10. 2023 Medium

    Refined prodrug bioactivation with enantiospecific ynone generation and distinguished HSD17B11 from its paralogue HSD17B13, providing a structural rationale for substrate recognition.

    Evidence Activity-based protein profiling, cell viability assays, AlphaFold model docking, and enantioselective synthesis

    PMID:37816126

    Open questions at the time

    • Docking is computational without experimental structure
    • Active-site residues governing selectivity not mutationally validated
11. 2024 Low

    Proposed a non-catalytic interaction role in which HSD17B11 binds GCKIII kinases to control hepatocellular lipid homeostasis.

    Evidence Genome-wide yeast two-hybrid screen of a hepatocyte library and lipid content assays following knockdown

    PMID:39395791

    Open questions at the time

    • Interaction from yeast two-hybrid not validated by reciprocal co-IP in mammalian cells
    • Conformational change mechanism not directly demonstrated
12. 2026 Medium

    Connected HSD17B11 to ferroptosis defense by showing it scaffolds FSP1 on lipid droplets and sustains FSP1 abundance, protecting against lipid oxidative stress.

    Evidence Lipid droplet protein purification with MS, immunoblotting, imaging, mutational analysis, and lipid oxidative stress assays

    PMID:42239065

    Open questions at the time

    • Preprint not yet peer-reviewed
    • Whether enzymatic activity is required for FSP1 maintenance unresolved
    • Structural basis of the HSD17B11-FSP1 interface not determined

• The endogenous physiological substrate and the direction of catalysis in vivo remain unresolved, as does whether HSD17B11's catalytic activity is required for its lipid-droplet scaffolding roles.
• No knockout-phenotype linking enzymatic activity to organismal steroid or lipid metabolism
• Mechanism coupling LD localization to FSP1 stability undefined
• No experimentally determined structure