ABHD17A

ABHD17A is a membrane-anchored serine hydrolase that acts as a protein depalmitoylase, accelerating the turnover of S-palmitoyl modifications on substrate proteins and thereby controlling their membrane association, subcellular localization, and downstream signaling (PMID:26701913). It was identified by activity-based serine-hydrolase profiling as a non-redundant depalmitoylase—distinct from APT1/APT2—that drives palmitate turnover on N-Ras and PSD-95, with its catalytic activity required to relocate N-Ras from the plasma membrane to internal membranes (PMID:26701913); in neurons it depalmitoylates PSD-95 from recycling endosomes and the synaptic compartment to regulate synaptic PSD-95 and AMPA receptor clustering (PMID:27307232). Its substrate range is broad, spanning cytoskeletal and signaling proteins such as MAP6 in axon maturation (PMID:28521134), TEAD transcription factors whose depalmitoylation promotes CHIP-mediated degradation in a density/Nf2-dependent manner (PMID:31043565), site-specific deacylation of the BK channel STREX domain (PMID:32913120), and CNAβ1 calcineurin (PMID:34663815). A recurring theme is direct antagonism of ZDHHC palmitoyltransferases at defined cysteines: ABHD17A counters ZDHHC5 on NLRP3, ZDHHC3 on SCAP, and ZDHHC24 on METTL3, thereby tuning inflammasome activity (PMID:38092000), cholesterol biosynthesis (PMID:39522165), and METTL3 condensate formation and stability (PMID:41719123). Through these activities it modulates innate immune signaling—NLRP3 and NOD2 deacylation linking it to Crohn's disease-associated variants (PMID:38092000, PMID:40054525)—as well as cancer cell migration via Rap2b (PMID:39277583). ABHD17A's own plasma-membrane targeting and catalytic activity are governed by a palmitoylation code in its N-terminal cysteine cluster and by YXXØ-dependent endosomal sorting (PMID:41155484), and it can paradoxically raise substrate palmitoylation indirectly by downregulating the competing depalmitoylase ABHD16A (PMID:40723864).

1. 2015 High

   Established that ABHD17 enzymes are a previously unrecognized class of protein depalmitoylase, resolving how palmitate turnover proceeds on N-Ras and PSD-95 independently of APT1/APT2.

   Evidence Dual pulse-chase of palmitate vs protein half-life, activity-based protein profiling, shRNA knockdown, Palmostatin B inhibition and localization imaging

   PMID:26701913

   Open questions at the time

   • Catalytic mechanism and structural basis of substrate selection not defined
   • Endogenous substrate repertoire beyond N-Ras/PSD-95 unknown at this stage
2. 2016 High

   Showed ABHD17A is a physiological PSD-95 depalmitoylase in neurons, linking its activity to synaptic receptor clustering and defining its endosomal/synaptic localization.

   Evidence Heterologous depalmitoylation assay, quantitative APEGS palmitoylation measurement, neuronal expression/knockdown, immunofluorescence and synaptic fractionation

   PMID:27307232

   Open questions at the time

   • Relative contribution of ABHD17A vs ABHD17B/C in vivo not separated
   • Mechanism targeting the enzyme to recycling endosomes not defined
3. 2017 Medium

   Extended substrate scope to cytoskeleton-associated MAP6, connecting depalmitoylation to microtubule stabilization and axon maturation.

   Evidence Live imaging, neuronal knockdown/overexpression, palmitoylation biochemistry, axonal localization assays

   PMID:28521134

   Open questions at the time

   • Direct enzyme-substrate interaction not biochemically isolated
   • ABHD17 isoform-specific roles not resolved
4. 2019 Medium

   Connected ABHD17A depalmitoylation to transcription-factor turnover, showing TEAD depalmitoylation routes it to CHIP-mediated proteasomal degradation under density/Nf2 control.

   Evidence ABHD17A overexpression, palmitoylation assays, cell-density manipulation, proteasome inhibition, Nf2/Merlin knockdown

   PMID:31043565

   Open questions at the time

   • Endogenous ABHD17A loss-of-function effect on TEAD not established
   • Shared role with APT2 not deconvolved
5. 2020 Medium

   Demonstrated site-specificity by showing ABHD17A deacylates only the STREX domain of BK channels (not S0-S1), establishing that distinct acylated domains of one protein are served by different thioesterases.

   Evidence Overexpression/knockdown, acyl-biotin exchange, electrophysiology, surface biotinylation

   PMID:32913120

   Open questions at the time

   • Structural basis for domain selectivity unknown
   • Single-lab finding
6. 2021 Medium

   Showed ABHD17A depalmitoylates CNAβ1 calcineurin to reverse its membrane/Golgi localization and alter its substrate specificity.

   Evidence Depalmitoylase overexpression, palmitoylation assays, localization imaging, HDX-MS substrate analysis

   PMID:34663815

   Open questions at the time

   • Physiological setting and endogenous regulation not established
7. 2023 High

   Defined ABHD17A as a direct ZDHHC5 antagonist on NLRP3 and tied it to inflammasome control and a Crohn's disease-associated NLRP3 variant with defective ABHD17A binding.

   Evidence Silencing/overexpression, palmitoylation assays, co-immunoprecipitation, inflammasome readouts (caspase-1, IL-1β, GSDMD), mutagenesis, in vivo mouse data

   PMID:38092000

   Open questions at the time

   • Determinants of NLRP3-ABHD17A binding interface not mapped
   • Causal disease contribution beyond association not established
8. 2024 Medium

   Identified ABHD17A as the Rap2b depalmitoylase regulated by PI3K-mediated phosphorylation, linking its activity to colorectal cancer cell migration and invasion.

   Evidence Overexpression/knockdown, palmitoylation assays, fractionation/localization, migration/invasion assays, PI3K inhibition

   PMID:39277583

   Open questions at the time

   • Phosphosite(s) on ABHD17A controlling activity not mapped
   • In vivo tumor relevance not established
9. 2024 Medium

   Showed ABHD17A antagonizes ZDHHC3 acylation of SCAP at C264 to modulate SCAP ubiquitination and cholesterol biosynthesis.

   Evidence Overexpression/knockdown, palmitoylation assays, ubiquitination assays, cholesterol measurement in hepatocellular carcinoma cells

   PMID:39522165

   Open questions at the time

   • Direct vs indirect effect on SCAP ubiquitination not fully separated
   • Single-lab, single-cell-context finding
10. 2025 Medium

    Established ABHD17 enzymes as the NOD2 deacylases controlling its membrane localization and NF-κB output, including for Crohn's-associated poorly-acylated variants.

    Evidence RNAi, small-molecule ABHD17 inhibitors, acyl-resin-assisted capture, confocal microscopy, cytokine multiplex assays

    PMID:40054525

    Open questions at the time

    • ABHD17A-specific contribution vs ABHD17B/C not isolated
    • Direct NOD2 binding not demonstrated
11. 2025 Medium

    Revealed an indirect, non-catalytic mode in which ABHD17A increases IFITM1 palmitoylation by downregulating the competing depalmitoylase ABHD16A, enhancing antiviral activity.

    Evidence Co-immunoprecipitation, palmitoylation assays, overexpression/knockdown of ABHD17A and ABHD16A, antiviral functional assays

    PMID:40723864

    Open questions at the time

    • Mechanism by which ABHD17A downregulates ABHD16A unknown
    • Direct vs indirect IFITM1 effect not fully resolved
12. 2025 Medium

    Defined the regulatory logic of ABHD17A itself: an N-terminal cysteine palmitoylation code and YXXØ endosomal sorting motif govern its PM targeting, catalytic activity, and trafficking.

    Evidence Alanine-scanning mutagenesis, confocal microscopy, acylation assays, substrate depalmitoylation assays

    PMID:41155484

    Open questions at the time

    • Enzymes writing/erasing the ABHD17A code not identified
    • Dynamics of the code under physiological signaling unknown
13. 2025 Low

    Implicated ABHD17A among the deacylases regulating GSDMA fatty-acylation cycling and pyroptosis.

    Evidence Biochemical deacylation assay and pyroptosis functional readout

    PMID:41972293

    Open questions at the time

    • Limited mechanistic detail on ABHD17A's specific role
    • ABHD17A-specific loss-of-function not isolated
14. 2026 Medium

    Showed ABHD17A depalmitoylates METTL3 at C376 to disrupt its condensates and promote chaperone-mediated autophagy, with a small molecule blocking the interaction alleviating osteoarthritis.

    Evidence Palmitoylation assays, co-IP, condensate imaging, KO/OE in cells and mice, OA models, AI-guided small-molecule screening

    PMID:41719123

    Open questions at the time

    • Structural basis of METTL3-ABHD17A binding not defined
    • Generalizability beyond osteoarthritis context unknown

• How ABHD17A achieves its broad yet site-specific substrate selectivity, and how its activity is dynamically regulated across tissues by phosphorylation and its own palmitoylation code, remains unresolved.
• No structure of ABHD17A or enzyme-substrate complex
• Determinants distinguishing direct depalmitoylation from indirect ABHD16A-mediated effects not generalized
• Isoform-specific (A vs B vs C) division of labor not systematically defined