DHRS3

DHRS3 is an NADPH-dependent short-chain dehydrogenase/reductase that reduces all-trans-retinaldehyde to retinol, functioning as a critical negative-feedback regulator of retinoic acid biosynthesis during embryonic development and adult tissue homeostasis. The enzyme is an integral ER membrane protein with its C-terminus facing the cytosol; it is also enriched at ER–lipid droplet junctions where it cooperates with LRAT for retinol esterification and storage, and its depletion elevates cellular ROS and disrupts NADP⁺/NADPH balance (PMID:25451588, PMID:21659514, PMID:41579973). DHRS3 transcription is strongly induced by retinoic acid via RAR/RXR heterodimers, and independently by p53 and TAp63γ through defined promoter response elements, embedding the enzyme in both retinoid and DNA-damage signaling networks (PMID:39420244, PMID:20543567, PMID:22790594). Biallelic loss-of-function DHRS3 variants in humans cause a developmental syndrome featuring craniosynostosis, congenital heart disease, and scoliosis, mirroring the cardiac, skeletal, and craniofacial defects observed in Dhrs3-knockout mice due to excess retinoic acid accumulation (PMID:40519748, PMID:24005908).

1. 2002 Medium

   Establishing that DHRS3 generates retinol for storage: overexpression of DHRS3 in neuroblastoma cells caused retinyl ester accumulation, providing the first direct evidence that the enzyme acts as a retinaldehyde reductase and that it is retinoic acid–inducible, suggesting a feedback role.

   Evidence Retinyl ester quantification after DHRS3 overexpression in SK-N-AS neuroblastoma cells; RA-treatment expression analysis

   PMID:11861404

   Open questions at the time

   • Enzymatic activity not demonstrated with purified protein
   • In vivo significance unknown at this point
   • Substrate specificity beyond retinal not tested
2. 2010 High

   Linking DHRS3 transcription to the p53/p63 tumor-suppressor axis: identification of two functional p53/TAp63γ response elements in the DHRS3 promoter showed that DNA-damage pathways directly activate retinaldehyde reduction, connecting retinoid metabolism to stress signaling.

   Evidence Promoter-reporter assays, ChIP, in vitro DNA binding, response element mutagenesis, testing of tumor-derived p53 and EEC-syndrome p63 mutants

   PMID:20543567

   Open questions at the time

   • Physiological consequence of p53-driven DHRS3 induction on retinoid levels not measured
   • Relationship to cell-cycle arrest or apoptosis unclear
3. 2011 Medium

   Defining DHRS3 subcellular localization: demonstration that DHRS3 resides in the ER directed by an N-terminal signal and concentrates at ER–lipid droplet budding sites revealed the compartment where retinaldehyde reduction and retinol storage are spatially coupled.

   Evidence Subcellular fractionation, fluorescence microscopy co-localization, N-terminal signal analysis in cultured cells

   PMID:21659514

   Open questions at the time

   • ER–lipid droplet targeting mechanism not molecularly defined
   • Functional interaction with lipid droplet biogenesis machinery not characterized
4. 2012 Medium

   Identifying the retinoic acid receptor isoform responsible for DHRS3 induction: RAR α-selective agonist recapitulated the 30–40-fold RA-mediated DHRS3 mRNA induction in monocytes, and inflammation (LPS) suppressed DHRS3 by >90%, revealing that the feedback loop is receptor-specific and context-dependent.

   Evidence Microarray and RT-qPCR in THP-1 cells with receptor-selective retinoid panel; rat in vivo LPS/RA dosing

   PMID:22790594

   Open questions at the time

   • Direct RARα binding to DHRS3 cis-regulatory elements not shown in this study
   • Mechanism of LPS-mediated suppression not resolved
5. 2013 High

   Proving DHRS3 is essential for retinoid homeostasis in vivo: Dhrs3-knockout mouse embryos accumulated 40% more ATRA, lost 60% of retinol, and exhibited cardiac/skeletal/palatal defects; independently, Xenopus Dhrs3 morphants phenocopied excess RA, establishing DHRS3 as a non-redundant developmental retinaldehyde reductase.

   Evidence Dhrs3-KO mouse with quantitative retinoid profiling and developmental phenotyping; Xenopus morpholino knockdown with epistasis analysis against Aldh1a2/Rdh10

   PMID:24005908 PMID:24045938

   Open questions at the time

   • Redundancy with other retinaldehyde reductases (e.g., RDH10 reverse activity) not fully quantified
   • Tissue-specific contributions during organogenesis not mapped
6. 2014 High

   Biochemical characterization of purified human DHRS3: reconstituted enzyme demonstrated NADPH preference, integral-membrane topology with cytosolic C-terminus, and activity toward steroids (androstenedione, estrone) and xenobiotics beyond retinal, establishing DHRS3 as a multi-substrate reductase.

   Evidence Recombinant expression, membrane fractionation, topology analysis, cofactor preference assay, in vitro activity assays with purified enzyme

   PMID:25451588

   Open questions at the time

   • Kinetic parameters for non-retinoid substrates not compared to retinal to assess physiological relevance
   • No structural model available
7. 2018 Medium

   Revealing post-transcriptional regulation of DHRS3: miR-223 directly targets the DHRS3 3ʹ UTR, and modulation of miR-223 levels controls osteogenic differentiation of mesenchymal stem cells through DHRS3-dependent retinoid signaling.

   Evidence Dual luciferase reporter assay, miR-223 mimic/inhibitor transfection with DHRS3 rescue, osteogenic marker analysis in hBMSCs

   PMID:29794437

   Open questions at the time

   • In vivo relevance of miR-223–DHRS3 axis in bone formation not tested
   • Retinoid metabolite levels not directly measured
8. 2024 Medium

   Closing the negative-feedback loop at the chromatin level: RAR/RXR heterodimers were shown to bind cis-regulatory elements within the Dhrs3 locus, and DHRS3 was found enriched in lipid droplets of undifferentiated melanoma cells where its overexpression drives cell-state transitions via RA pathway modulation.

   Evidence Vitamin A manipulation in mice with RAR/RXR binding assays; melanoma lipid droplet proteomics and DHRS3 overexpression with cell-state markers

   PMID:39420244 PMID:39479752

   Open questions at the time

   • Exact cis-regulatory element sequences and their necessity not dissected by deletion
   • Causality in melanoma phenotype switching needs in vivo validation
9. 2025 High

   Establishing human disease causation: biallelic DHRS3 hypomorphic variants (including Val171Met) cause a Mendelian syndrome of craniosynostosis, congenital heart disease, and scoliosis; patient plasma showed reduced retinol and elevated RA, and the variant enzyme had diminished retinaldehyde reductase activity, confirming the mouse-predicted essentiality in humans.

   Evidence Multi-family patient cohort, in vitro enzymatic assay of DHRS3-V171M, plasma retinoid metabolite quantification

   PMID:40519748

   Open questions at the time

   • Genotype–phenotype correlation across different variant classes not yet established
   • Rescue experiments in patient-derived cells not reported
10. 2026 Medium

    Uncovering two new regulatory axes: DHRS3 protein directly interacts with Nrf2 (forming a mutual negative-feedback loop), and YTHDF2 maintains DHRS3 expression through m6A modification of its 3ʹ UTR; LRAT co-localizes DHRS3 to ER–lipid droplet–mitochondria contact sites where its loss elevates ROS and disrupts NADP⁺/NADPH balance.

    Evidence Co-IP, GST pull-down, SPR, CETSA for Nrf2 interaction; MeRIP-seq/qPCR and reporter assays for m6A-YTHDF2 axis; spatial imaging, DHRS3/LRAT knockdown with ROS/NADPH measurements

    PMID:41579973 PMID:41993611

    Open questions at the time

    • DHRS3–Nrf2 interaction domain and stoichiometry not mapped
    • Whether DHRS3's redox role at mitochondria-adjacent sites is retinoid-dependent or independent not resolved
    • Single-lab findings for each axis await independent replication

• Key unresolved questions include: the three-dimensional structure of DHRS3, the relative physiological importance of its non-retinoid substrates, the molecular basis of tissue-specific regulation during organogenesis, and whether the Nrf2 interaction and m6A regulation are relevant in developmental contexts.
• No crystal or cryo-EM structure solved
• Physiological relevance of steroid/xenobiotic reduction versus retinaldehyde reduction not delineated
• Conditional tissue-specific knockout studies not reported