HSD17B11

HSD17B11 is a short-chain dehydrogenase/reductase (SDR) that functions in androgen inactivation, lipid droplet biology, and xenobiotic bioactivation. It catalyzes the NAD⁺-dependent oxidation of 5α-androstane-3α,17β-diol to androsterone and acts on 17β-hydroxysteroids but not glucocorticoids, localizing to the endoplasmic reticulum and lipid droplets of steroidogenic tissues including adrenal cortex, Leydig cells, and syncytiotrophoblasts (PMID:12697717, PMID:9888557, PMID:30358111). HSD17B11 also bioactivates alkynylcarbinol prodrugs by oxidizing their carbinol center to generate protein-reactive electrophilic ketones that covalently modify proteostasis machinery, triggering ER stress, unfolded protein response activation, and apoptosis (PMID:35535493, PMID:37816126). Beyond steroid metabolism, HSD17B11 promotes lipid droplet formation downstream of FTO/m6A-mediated mRNA regulation in cancer cells and interacts with GCKIII kinases (MST3, STK25, MST4) to regulate hepatocellular lipid homeostasis (PMID:35568876, PMID:39395791).

1. 1998 Medium

   Establishing that HSD17B11 (Pan1b) possesses dehydrogenase activity toward 17β-hydroxysteroids but not glucocorticoids resolved its substrate class specificity and distinguished it from the 11β-HSD family.

   Evidence Substrate metabolism assays in CHO cells expressing recombinant protein

   PMID:9888557

   Open questions at the time

   • Endogenous oxidoreductase activity in CHO cells could confound substrate specificity determination
   • Preferred physiological substrate not defined
   • Kinetic parameters not reported
2. 2003 High

   Identification of the specific reaction — oxidation of 5α-androstane-3α,17β-diol to androsterone — and localization to steroidogenic cells (Leydig, granulosa, syncytiotrophoblast, adrenal cortex) established HSD17B11 as an androgen-inactivating enzyme in reproductive and endocrine tissues.

   Evidence Enzymatic activity assays in transfected cells, immunohistochemistry across multiple tissues, Northern blot, cAMP regulation in mouse Y1 adrenal cells

   PMID:12697717

   Open questions at the time

   • Crystal structure not available to explain substrate selectivity
   • Relevance of the 5′ UTR poly-A polymorphism to disease phenotypes unknown
   • In vivo contribution to circulating androgen levels not tested
3. 2010 High

   Demonstrating that C/EBPα and C/EBPβ induce HSD17B11 expression — but not through the proximal CCAAT boxes — revealed indirect or distal transcriptional regulation, complemented in 2011 by showing that Sp1 and C/EBPα directly bind and activate the proximal promoter in prostate cancer cells.

   Evidence Reporter assays, promoter mutagenesis, DAPA, ChIP in prostate cancer cells (2011); ectopic C/EBP expression in HepG2 cells (2010)

   PMID:20638476 PMID:21549806

   Open questions at the time

   • Chromatin context and epigenetic regulation of the HSD17B11 locus not explored
   • Whether Sp1/C/EBP regulation operates in non-cancerous steroidogenic tissues is untested
4. 2018 Medium

   Proteomic identification of HSD17B11 on adrenal lipid droplets established a second subcellular compartment (beyond ER) where steroid-metabolizing SDR activity resides.

   Evidence LD proteomics from human, macaque, and rodent adrenal glands with Western blot fractionation validation

   PMID:30358111

   Open questions at the time

   • Whether LD-localized HSD17B11 is enzymatically active on steroids at the droplet surface is not demonstrated
   • Targeting signal directing HSD17B11 to LDs not identified
5. 2019 Medium

   Knockdown of HSD17B11 in goat IVF embryos decreased developmental rates, revealing a non-steroidogenic role during embryonic genome activation.

   Evidence RNA knockdown in goat IVF embryos with developmental rate quantification

   PMID:30407918

   Open questions at the time

   • Mechanism by which HSD17B11 supports embryonic development is unknown
   • Not confirmed in mammalian species other than goat
   • Whether the effect is steroid-dependent or lipid-metabolism-dependent is unclear
6. 2020 Medium

   A genome-wide CRISPR screen identified HSD17B11 as required for the selective cytotoxicity of the alkynylcarbinol dehydrofalcarinol, linking its SDR activity to xenobiotic bioactivation for the first time.

   Evidence CRISPR-Cas9 knockout screen in MDA-MB-231 triple-negative breast cancer cells

   PMID:33021790

   Open questions at the time

   • Enzymatic mechanism of bioactivation not yet characterized at this point
   • Whether other SDR family members contribute to alkynylcarbinol metabolism not addressed
7. 2022 High

   Biochemical characterization showed HSD17B11 oxidizes alkynylcarbinols to protein-reactive electrophilic ketones that covalently modify proteostasis machinery (via Michael addition on Cys/Lys residues), causing ER stress, UPR activation, proteasome inhibition, and apoptosis — defining a complete prodrug bioactivation mechanism.

   Evidence In vitro enzymatic assay, mass spectrometry of protein adducts, clickable probes, ER stress and cell death assays in haploid human cells

   PMID:35535493

   Open questions at the time

   • No co-crystal structure of HSD17B11 with alkynylcarbinol substrate
   • Full spectrum of covalently modified protein targets not catalogued
   • In vivo bioactivation pharmacokinetics not established
8. 2022 Medium

   Discovery that FTO demethylates m6A on HSD17B11 mRNA to increase its expression — with YTHDF1 acting as a negative translational regulator — and that elevated HSD17B11 drives lipid droplet formation established an epitranscriptomic–lipid metabolism axis in esophageal cancer.

   Evidence meRIP-seq, FTO knockdown/overexpression, YTHDF1 depletion, and lipid droplet quantification in esophageal cancer cells

   PMID:35568876

   Open questions at the time

   • Whether the lipid droplet phenotype requires HSD17B11 enzymatic activity or a non-catalytic scaffolding role is unknown
   • Single cancer cell line study; generalizability to normal tissues untested
9. 2023 Medium

   Enantiospecific bioactivation of phenyl-dialkynylcarbinols by HSD17B11 and molecular docking to its AlphaFold model provided a structural rationale for substrate selectivity over its paralogue HSD17B13.

   Evidence Clickable probe experiments, cytotoxicity assays, molecular docking to AlphaFold-predicted structure

   PMID:37816126

   Open questions at the time

   • Structural model is computational (AlphaFold), not experimentally determined
   • Selectivity determinants not validated by site-directed mutagenesis
10. 2024 Medium

    Identification of GCKIII kinases (MST3, STK25, MST4) as HSD17B11 interaction partners in hepatocytes placed HSD17B11 in a kinase-regulatory circuit controlling lipid homeostasis, expanding its role beyond steroid metabolism.

    Evidence Genome-wide yeast two-hybrid screen of human hepatocyte library with functional lipid content assays

    PMID:39395791

    Open questions at the time

    • Interaction not confirmed by reciprocal co-immunoprecipitation or in vivo methods
    • Conformational change mechanism claimed but not biochemically demonstrated
    • Direct vs. indirect effect on hepatocellular lipid content not resolved

• The in vivo physiological significance of HSD17B11 in androgen metabolism, lipid homeostasis, and embryonic development remains unresolved, as no knockout animal model or human genetic disease association has been reported.
• No animal knockout phenotype reported
• No human Mendelian disease linked to HSD17B11 mutations
• Relative contribution of HSD17B11 versus other 17β-HSDs to systemic androgen inactivation unknown
• Experimental crystal structure unavailable