ZDHHC4

ZDHHC4 is an ER/membrane-localized palmitoyl acyltransferase that catalyzes S-palmitoylation of a structurally diverse set of substrates to control their stability, subcellular trafficking, and downstream signaling across innate immunity, pain, metabolism, and cancer (PMID:38016475, PMID:39528731, PMID:40357580). A recurrent mechanistic theme is that ZDHHC4-mediated palmitoylation governs substrate fate through two routes: directing membrane or nuclear localization, and modulating ubiquitin-dependent stability. In innate immunity, ZDHHC4 is recruited by CPT1A to palmitoylate MAVS at Cys79, blocking K48-linked ubiquitination while favoring K63-linked ubiquitination to stabilize MAVS and sustain the type I interferon response (PMID:38016475); an analogous stabilization mechanism operates on ZEB-2 (palmitoylation at C478 promoting deubiquitination) to drive EMT in melanoma (PMID:41603995). ZDHHC4 also controls trafficking-dependent activity: it palmitoylates KAI1/CD82 and the D2 dopamine receptor to direct their plasma-membrane localization and stability (PMID:34530889, PMID:26535572), drives nuclear translocation of NFATC4 (PMID:35150145), and—in metabolic tissues—S-acylates CD36 to promote its sarcolemmal/plasma-membrane localization, fatty-acid uptake and oxidation, with ZDHHC4 expression itself transcriptionally upregulated by FoxO1 in the diabetic heart (PMID:40357580, PMID:39047111, PMID:41306774). Conversely, ZDHHC4 palmitoylation of TRPV1 at C157/C362/C390/C715 targets the channel for lysosomal degradation, a modification opposed by the depalmitoylase APT1 and tuning inflammatory pain (PMID:39528731). Through palmitoylation of GSK3β at Cys14 it activates the EZH2-STAT3 axis in glioblastoma stem cells (PMID:35606353), and palmitoylation of CCDC50 links it to selective autophagy of MAP2K4 and suppression of MAPK/JNK signaling (PMID:41566717). Its enzymatic activity is regulated at the residue level, being boosted by the small molecule lactucopicrin binding His72 (PMID:41566717).

1. 2015 Medium

   Established ZDHHC4 as a bona fide acyltransferase acting on a membrane receptor, addressing whether it physically engages and modifies substrates to control their surface expression.

   Evidence Membrane yeast two-hybrid screen, Co-IP and click-chemistry palmitoylation assay with D2R cysteine mutagenesis

   PMID:26535572

   Open questions at the time

   • Single lab without reciprocal in vitro reconstitution of ZDHHC4 enzymatic activity
   • Did not define ZDHHC4 catalytic residues
   • Trafficking mechanism downstream of palmitoylation not resolved
2. 2021 Medium

   Extended ZDHHC4 substrate repertoire to a tetraspanin and a viral glycoprotein, showing palmitoylation controls membrane localization and downstream signaling versus viral fusion.

   Evidence KAI1 knockout mice with palmitoylation and angiogenesis assays; Co-IP and pseudovirus/syncytia assays for SARS-CoV-2 S protein

   PMID:34528721 PMID:34530889

   Open questions at the time

   • No ZDHHC4-specific site mutagenesis for the S protein
   • Direct catalytic role not separated from family redundancy in the viral study
3. 2022 Medium

   Showed ZDHHC4 palmitoylation can both activate a kinase and license a transcription factor's nuclear entry, broadening its role to oncogenic and Ca2+-homeostasis signaling.

   Evidence Site-directed mutagenesis (GSK3β Cys14) with EZH2-STAT3 readouts in GBM stem cells; NFATC4 palmitoylation and fractionation in Ppt1-/- mice with IP3R1 rescue

   PMID:35150145 PMID:35606353

   Open questions at the time

   • NFATC4 modification shared with ZDHHC8 and not individually resolved
   • Direct enzyme-substrate kinetics not established
4. 2023 High

   Defined the highest-confidence mechanism: CPT1A-recruited ZDHHC4 palmitoylates MAVS at Cys79 to redirect ubiquitin signals (suppressing K48, favoring K63) and sustain interferon responses.

   Evidence Reciprocal Co-IP, Cys79 mutagenesis, palmitoylation and K48/K63 ubiquitination assays, in vivo IFN-I readouts

   PMID:38016475

   Open questions at the time

   • Structural basis of CPT1A-ZDHHC4 recruitment not solved
   • Whether MAVS palmitoylation is reversed by a specific depalmitoylase unaddressed
5. 2024 High

   Connected ZDHHC4 to substrate degradation rather than stabilization, and to physiological metabolism, establishing context-dependent outcomes of palmitoylation.

   Evidence TRPV1 four-site mutagenesis with lysosomal degradation, electrophysiology and pain behavior plus APT1 opposition; ATF3-driven CD36 palmitoylation with fractionation in a MASH model

   PMID:39047111 PMID:39528731

   Open questions at the time

   • CD36 study did not individually resolve ZDHHC4 from ZDHHC5
   • How substrate identity dictates lysosomal versus stabilizing fate is unexplained
6. 2025 High

   Placed ZDHHC4 within transcriptional regulatory circuits controlling cardiac and hepatic lipid handling via CD36 palmitoylation.

   Evidence FoxO1 ChIP-seq/luciferase and cardiomyocyte FoxO1 KO with cross-species S-acylation assays; hepatocyte Eva1a KO with ZDHHC4/5 and APT1 transcriptional analysis

   PMID:40357580 PMID:41306774

   Open questions at the time

   • EVA1A study did not resolve ZDHHC4 from ZDHHC5
   • Direct ZDHHC4 enzymatic specificity for CD36 cysteines not isolated from family members
7. 2026 Medium

   Identified a stabilizing substrate (ZEB-2) and a pharmacological activation handle (His72), advancing ZDHHC4 as a druggable enzyme with defined regulatory residues.

   Evidence Mass spectrometry, Co-IP and C478 mutagenesis for ZEB-2; DARTS binding to His72 by lactucopicrin with CCDC50 palmitoylation and autophagy/MAPK readouts

   PMID:41566717 PMID:41603995

   Open questions at the time

   • No crystal/cryo-EM structure confirming His72 as an activation site
   • ZEB-2 deubiquitinase linking palmitoylation to stability not identified

• How ZDHHC4 selects among its many substrates and whether outcomes (membrane targeting, nuclear import, stabilization, or lysosomal degradation) are dictated by adaptor recruitment, localization, or substrate context remains unresolved.
• No structural model of ZDHHC4 substrate engagement
• Catalytic and regulatory residues largely uncharacterized beyond His72
• Redundancy with ZDHHC5/ZDHHC8 not systematically dissected