Affinage

DDHD2

Triacylglycerol hydrolase DDHD2 · UniProt O94830

Length
711 aa
Mass
81.0 kDa
Annotated
2026-04-28
26 papers in source corpus 14 papers cited in narrative 14 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

DDHD2 is a multifunctional serine hydrolase that serves as the principal brain triglyceride and diacylglycerol lipase and additionally possesses transacylase activity, controlling neuronal lipid droplet catabolism and supplying long-chain saturated free fatty acids for mitochondrial β-oxidation and ATP production (PMID:25267624, PMID:27198176, PMID:41264248, PMID:41028912). It localizes to the cytosol, cis-Golgi, and ERGIC where it mediates a COPI- and Rab6-independent retrograde Golgi-to-ER transport pathway, and is targeted to the plasma membrane through interaction with STXBP1 to generate saturated free fatty acids critical for synaptic plasticity and memory (PMID:19632984, PMID:38316990). DDHD2 also functions as a lipophagy cargo receptor through two LIR motifs that bind LC3/GABARAP family proteins, coupling direct lipase activity with autophagic lipid droplet clearance (PMID:38332048). Loss-of-function mutations cause hereditary spastic paraplegia SPG54, characterized by ectopic neuronal lipid droplet accumulation, reduced cardiolipin, mitochondrial dysfunction with excess ROS, motor neuron apoptosis, and impaired memory (PMID:23176823, PMID:30038238, PMID:38316990).

Mechanistic history

Synthesis pass · year-by-year structured walk · 11 steps
  1. 2009 High

    Before this work, DDHD2's subcellular site of action and membrane trafficking role were unknown; this study established that DDHD2 localizes to the cytosol, cis-Golgi, and ERGIC and mediates a specific COPI- and Rab6-independent retrograde Golgi-to-ER transport pathway.

    Evidence RNAi knockdown with BFA redistribution, cholera toxin B transport, and live-cell imaging assays in cultured cells

    PMID:19632984

    Open questions at the time
    • Molecular mechanism by which DDHD2 lipase activity drives membrane tubulation or carrier formation remains undefined
    • Whether this transport function operates in neurons was not tested
  2. 2012 High

    The genetic basis of SPG54 was unknown; exome sequencing revealed that loss-of-function mutations in the DDHD domain of DDHD2 cause hereditary spastic paraplegia, and Drosophila knockdown linked the gene to synaptic maintenance.

    Evidence Exome sequencing of multiple SPG54 families, domain analysis, Drosophila RNAi with active zone quantification

    PMID:23176823

    Open questions at the time
    • Enzymatic activity of patient-derived mutants was not directly measured in this study
    • Mechanism connecting lipase loss to motor neuron degeneration was not established
  3. 2014 High

    Whether DDHD2 was a physiologically relevant brain lipase was unknown; DDHD2-knockout mice and a selective inhibitor demonstrated that DDHD2 is the principal brain TAG hydrolase, and patient brain MRS confirmed lipid accumulation from reduced PLA1 activity.

    Evidence DDHD2−/− mouse model, selective in vivo inhibitor, lipidomics, recombinant TAG hydrolase assay, patient MR spectroscopy and PLA1 activity measurement

    PMID:25267624 PMID:25417924

    Open questions at the time
    • Whether DDHD2 acts primarily on TAG versus DAG in vivo was not resolved
    • The downstream metabolic fate of released fatty acids was not traced
  4. 2016 High

    DDHD2's substrate preference among neutral lipids was unclear; kinetic characterization showed it preferentially hydrolyzes DAG over TAG or PA, with selectivity for polyunsaturated sn-2 species, and generates 2-AG in cells.

    Evidence Purified recombinant rat DDHD2, LC-MS substrate specificity assays, GC-MS/MS quantification of 2-AG in CHO cells

    PMID:27198176

    Open questions at the time
    • Physiological relevance of 2-AG production by DDHD2 versus canonical DAGL pathway not established
    • Neuronal context not directly examined
  5. 2017 High

    How HSP-associated mutations impair DDHD2 function was unknown; this work showed that disease mutations abolish TAG hydrolase activity and lipid droplet clearance capacity, and proteomic analysis of brain LDs from KO mice revealed neurological disease-associated proteins.

    Evidence In vitro TAG hydrolase assays with HSP mutant proteins, cell-based LD accumulation assays, LD proteomics from DDHD2−/− brain

    PMID:29278326

    Open questions at the time
    • Whether LD-associated disease proteins contribute to neurodegeneration in DDHD2 loss was not tested
    • Structure-function relationship of each HSP mutation was not fully resolved
  6. 2018 High

    The mechanism linking DDHD2 loss to motor neuron death was unknown; KO mice revealed age-dependent motor neuron apoptosis driven by reduced cardiolipin and elevated ROS, rescued only by catalytically active wild-type DDHD2.

    Evidence DDHD2−/− mice, spinal cord histology, ROS and cardiolipin quantification, rescue with WT vs. catalytic-dead and HSP mutant constructs

    PMID:30038238

    Open questions at the time
    • How DDHD2 lipase activity maintains cardiolipin levels is not mechanistically defined
    • Whether mitochondrial dysfunction precedes or follows LD accumulation was not resolved
  7. 2023 High

    The relationship between DDHD2 and ATGL in neuronal lipolysis was unclear; this study showed DDHD2 acts downstream of ATGL on sn-1,3-DAG isomers and has neuron-specific dual TAG/DAG hydrolase function that complements ATGL.

    Evidence Purified enzyme assays, neutral lipid hydrolase measurements in neuroblastoma cells and brain tissue, primary cortical neuron KO/KD experiments

    PMID:37832604

    Open questions at the time
    • Whether other lipases compensate for DDHD2 loss in specific neuronal subtypes is unknown
    • Regulation of DDHD2-ATGL cooperation not defined
  8. 2024 High

    How DDHD2 interfaces with autophagy to clear lipid droplets was unknown; discovery of two functional LIR motifs established DDHD2 as a lipophagy cargo receptor that bridges LDs to LC3/GABARAP-decorated autophagic membranes.

    Evidence AP-MS, LIR motif mutagenesis, LC3B-LD colocalization microscopy, KO cell assays, pharmacological rescue with LD·ATTEC

    PMID:38332048

    Open questions at the time
    • Relative contribution of direct lipase activity versus lipophagy receptor function to LD clearance in vivo is unquantified
    • Whether lipophagy receptor activity requires catalytic competence is not established
  9. 2024 High

    DDHD2's plasma membrane targeting mechanism and role in memory were unknown; identification of STXBP1 as a binding partner showed it controls DDHD2 PM targeting and saturated FFA generation, while DDHD2 KO mice displayed impaired reward-based and spatial memory.

    Evidence Pulldown-MS, STXBP1/2 KO neurosecretory cells, STXBP1+/− mice, brain lipidomics, behavioral testing in DDHD2−/− mice

    PMID:38316990

    Open questions at the time
    • Whether STXBP1-dependent PM targeting is required for the lipophagy function is untested
    • Specific synaptic mechanisms connecting FFA generation to memory formation are not defined
  10. 2025 High

    The metabolic consequence of DDHD2-released fatty acids in neurons was unknown; this work revealed that neurons depend on DDHD2-derived long-chain saturated FFAs for mitochondrial β-oxidation and ATP synthesis, overturning the assumption that neurons do not use significant fatty acid oxidation.

    Evidence DDHD2 KO neurons, Seahorse respiration assays, pharmacological FA import inhibition, saturated acyl-CoA supplementation rescue

    PMID:41028912

    Open questions at the time
    • Whether β-oxidation dependence is universal across neuronal subtypes or restricted to certain populations is not known
    • In vivo contribution of neuronal FA oxidation to total brain energy budget not quantified
  11. 2025 High

    Whether DDHD2 possesses activities beyond hydrolysis was unknown; reconstitution showed DDHD2 is also a transacylase that transfers acyl chains between neutral lipids, and identified a hydrophobic amphipathic helix essential for LD binding and enzymatic function.

    Evidence Recombinant human DDHD2 lipase and transacylase assays in vitro, amphipathic helix deletion/mutation, cell-based LD binding assays

    PMID:41264248

    Open questions at the time
    • Structural basis of transacylase mechanism at atomic resolution is lacking
    • Physiological significance of acyl-chain remodeling versus simple hydrolysis in neurons is not delineated

Open questions

Synthesis pass · forward-looking unresolved questions
  • Key unresolved questions include: (1) the structural basis for DDHD2's dual lipase/transacylase catalysis; (2) how its lipophagy receptor and direct lipase activities are coordinately regulated in vivo; and (3) the neuron subtype-specific requirements for DDHD2-dependent fatty acid β-oxidation in brain energy metabolism and disease.
  • No high-resolution structure of DDHD2
  • Relative in vivo contributions of lipase vs. transacylase vs. lipophagy receptor activities are unquantified
  • Therapeutic strategies targeting DDHD2 pathway for SPG54 have not been tested

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0016787 hydrolase activity 5 GO:0008289 lipid binding 1 GO:0016740 transferase activity 1 GO:0038024 cargo receptor activity 1
Localization
GO:0005811 lipid droplet 3 GO:0005783 endoplasmic reticulum 1 GO:0005794 Golgi apparatus 1 GO:0005829 cytosol 1 GO:0005886 plasma membrane 1
Pathway
R-HSA-1430728 Metabolism 5 R-HSA-1643685 Disease 3 R-HSA-112316 Neuronal System 2 R-HSA-5653656 Vesicle-mediated transport 1 R-HSA-9612973 Autophagy 1
Partners
ATGLGABARAPLC3BSTXBP1

Evidence

Reading pass · 14 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2012 DDHD2 encodes an intracellular phospholipase A1 (iPLA1); mutations affecting the DDHD domain, which is vital for phospholipase activity, cause hereditary spastic paraplegia (SPG54). Knockdown of the Drosophila ortholog reduced active zones at synaptic terminals, linking DDHD2 to synaptic function. Human genetics (exome sequencing), domain analysis, Drosophila RNAi knockdown with morphological readout at synaptic terminals American journal of human genetics High 23176823
2009 iPLA1gamma (DDHD2/KIAA0725p) localizes to the cytosol, cis-Golgi, and ERGIC; it mediates a specific COPI- and Rab6-independent retrograde membrane transport pathway from the Golgi to the ER. Knockdown delays brefeldin A-induced Golgi-to-ER membrane transfer and cholera toxin B retrograde transport but not ERGIC-53 recycling or Shiga toxin delivery. RNAi knockdown, live-cell time-lapse microscopy, immunofluorescence localization, transport assays (BFA redistribution, cholera toxin B, VSVGts045, ERGIC-53, Shiga toxin) The Journal of biological chemistry High 19632984
2014 DDHD2 is the principal triglyceride (triacylglycerol, TAG) hydrolase in the brain. DDHD2-/- mice show age-dependent TAG elevation specifically in the CNS, with large lipid droplets accumulating in neuronal intracellular compartments. Recombinant DDHD2 displays TAG hydrolase activity in vitro, and a selective DDHD2 inhibitor recapitulates TAG accumulation in wild-type mice. DDHD2-/- mouse model, selective in vivo-active inhibitor, mass spectrometry-based lipidomics, recombinant protein in vitro TAG hydrolase assay, electron microscopy Proceedings of the National Academy of Sciences of the United States of America High 25267624
2014 A homozygous missense mutation in DDHD2 causes a marked reduction of phospholipase A1 activity, and brain MRS reveals an abnormal lipid peak, confirming that loss of DDHD2 enzymatic activity underlies lipid accumulation in SPG54 patients. Exome sequencing, phospholipase A1 activity assay on patient-derived material, MR spectroscopy Scientific reports Medium 25417924
2016 Recombinant rat DDHD2 preferentially hydrolyzes diacylglycerol (DG) over triacylglycerol (TG) or phosphatidic acid (PA), with highest activity toward DG species bearing a polyunsaturated fatty acid at the sn-2 position. DDHD2 overexpression in CHO cells raises 2-arachidonoylglycerol (2-AG) levels under MAGL inhibition, indicating DDHD2 functions as a DG lipase producing 2-AG in vivo. In vitro enzyme kinetics with purified recombinant protein, LC-MS substrate specificity assays, GC-MS/MS quantification of 2-AG in cells Journal of biochemistry High 27198176
2017 HSP-related mutations in DDHD2 disrupt triglyceride hydrolase activity in vitro and impair the capacity of DDHD2 to protect cells from lipid droplet (LD) accumulation upon free fatty acid exposure. LDs isolated from DDHD2-/- mouse brains contain established LD-associated proteins and CNS-enriched proteins, including those with genetic links to neurological disease. In vitro TAG hydrolase assay with HSP mutant proteins, cell-based LD accumulation assay with fatty acid loading, LD isolation and proteomic characterization from DDHD2-/- mouse brain Biochemistry High 29278326
2018 DDHD2 ablation in mice induces age-dependent apoptosis of spinal cord motor neurons. DDHD2 KO cells show decreased cardiolipin content and increased reactive oxygen species (ROS). Restoration of wild-type DDHD2, but not an active-site mutant or HSP-related DDHD2 mutants or the paralog DDHD1, reverses ROS production, demonstrating that DDHD2 phospholipase/lipase activity is required for mitochondrial integrity. DDHD2-/- mouse model, histology of spinal cord, chemical and probe-based ROS analysis, cardiolipin quantification, rescue with WT vs. catalytic mutant DDHD2 constructs Cell death & disease High 30038238
2023 DDHD2 cooperates with ATGL in neuronal lipolysis. In neuroblastoma cells, DDHD2 acts downstream of ATGL, hydrolyzing sn-1,3-diacylglycerol (DAG) isomers. In primary cortical neurons, DDHD2 has dual control over both TAG and DAG hydrolysis and complements ATGL-dependent TAG hydrolysis, revealing neuron-specific lipolysome configurations. In vitro lipase assays with purified enzymes, neutral lipid hydrolase activity measurements in neuroblastoma cells and brain tissue, primary cortical neuron experiments, DDHD2/ATGL knockdown/KO Journal of lipid research High 37832604
2024 DDHD2 interacts with multiple ATG8 family proteins (LC3s and GABARAPs) via two authentic LIR motifs, promoting lipophagy. DDHD2 enhances colocalization of LC3B with lipid droplets. Both the LC3/GABARAP-binding capacity and canonical autophagy pathway contribute to DDHD2's LD-eliminating activity. Affinity purification-mass spectrometry (AP-MS), mutational analysis of LIR motifs, colocalization microscopy, DDHD2 overexpression/KO cell assays, pharmacological rescue with LD·ATTEC Cell death and differentiation High 38332048
2024 DDHD2 binds the key synaptic protein STXBP1. STXBP1 controls targeting of DDHD2 to the plasma membrane and generation of saturated free fatty acids (particularly myristic acid, C14:0) in the brain. Genetic ablation of DDHD2 dramatically reduces saturated FFA responses to memory acquisition and impairs reward-based and spatial memory performance. Pulldown-mass spectrometry, STXBP1/2 KO neurosecretory cells, haploinsufficient STXBP1+/- mice, lipidomics, behavioral testing in DDHD2-/- mice The EMBO journal High 38316990
2025 DDHD2 possesses both lipase and transacylase activities. Recombinant human DDHD2 preferentially hydrolyzes DAG over phospholipids, and transfers acyl chains from TAGs to DAGs and monoacylglycerols, remodeling TAG acyl chain composition. A hydrophobic amphipathic helix on DDHD2 is essential for lipid droplet binding in vitro and in cells; its deletion reduces enzymatic activity and TAG acyl chain remodeling. In vitro assays with recombinant human DDHD2, lipase and transacylase activity measurements, domain deletion/mutation analysis, cell-based lipid droplet binding assays Proceedings of the National Academy of Sciences of the United States of America High 41264248
2025 Genetic ablation of DDHD2 impairs mitochondrial respiration and ATP synthesis in cultured neurons despite increased glycolysis, due to reduced long-chain saturated free fatty acids (myristic, palmitic, stearic acids). Inhibition of mitochondrial fatty acid import in wild-type neurons similarly reduces mitochondrial respiration and ATP. Saturated fatty acyl-CoA treatment restores mitochondrial energy production in DDHD2 KO neurons, revealing that neurons use β-oxidation of DDHD2-released fatty acids for energy. DDHD2 KO neurons, Seahorse mitochondrial respiration assay, glycolysis measurement, pharmacological inhibition of mitochondrial FA import, fatty acyl-CoA supplementation rescue Nature metabolism High 41028912
2024 DDHD2 interacts with Nrf2; DDHD2 knockdown in human artery endothelial cells decreases Nrf2 and GPX4 protein levels, increases lipid peroxidation, and promotes ferroptosis, suggesting DDHD2 regulates the Nrf2/GPX4 anti-ferroptosis pathway. Co-immunoprecipitation, DDHD2 siRNA knockdown, GPX4/Nrf2 western blotting, lipid peroxidation assays in HAECs Biomolecules Low 39062593
2025 Acute DDHD2 inhibition-induced lipid droplet accumulation in primary rat cortical neurons does not affect total levels, phosphoserine-129 status, or solubility of endogenous α-synuclein, and no colocalization between LDs and α-synuclein is observed, indicating DDHD2-regulated lipid homeostasis is not sufficient to directly alter α-synuclein biochemistry. Pharmacological DDHD2 inhibitor (KLH45) in primary neurons, western blotting, immunofluorescence colocalization Metabolic brain disease Medium 39853540

Source papers

Stage 0 corpus · 26 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2012 Mutations in DDHD2, encoding an intracellular phospholipase A(1), cause a recessive form of complex hereditary spastic paraplegia. American journal of human genetics 149 23176823
2014 The hereditary spastic paraplegia-related enzyme DDHD2 is a principal brain triglyceride lipase. Proceedings of the National Academy of Sciences of the United States of America 145 25267624
2020 Common genetic risk variants identified in the SPARK cohort support DDHD2 as a candidate risk gene for autism. Translational psychiatry 69 32747698
2013 Mutations in phospholipase DDHD2 cause autosomal recessive hereditary spastic paraplegia (SPG54). European journal of human genetics : EJHG 61 23486545
2013 Mutations in CYP2U1, DDHD2 and GBA2 genes are rare causes of complicated forms of hereditary spastic paraparesis. Journal of neurology 60 24337409
2017 Functional Contribution of the Spastic Paraplegia-Related Triglyceride Hydrolase DDHD2 to the Formation and Content of Lipid Droplets. Biochemistry 46 29278326
2009 Intracellular phospholipase A1gamma (iPLA1gamma) is a novel factor involved in coat protein complex I- and Rab6-independent retrograde transport between the endoplasmic reticulum and the Golgi complex. The Journal of biological chemistry 42 19632984
2021 Circular RNA circRUNX1 promotes papillary thyroid cancer progression and metastasis by sponging MiR-296-3p and regulating DDHD2 expression. Cell death & disease 39 33479208
2018 Loss of DDHD2, whose mutation causes spastic paraplegia, promotes reactive oxygen species generation and apoptosis. Cell death & disease 29 30038238
2014 Late-onset spastic ataxia phenotype in a patient with a homozygous DDHD2 mutation. Scientific reports 28 25417924
2024 The DDHD2-STXBP1 interaction mediates long-term memory via generation of saturated free fatty acids. The EMBO journal 22 38316990
2015 miR-503 represses human cell proliferation and directly targets the oncogene DDHD2 by non-canonical target pairing. BMC genomics 20 25653011
2015 Truncating mutation in intracellular phospholipase A₁ gene (DDHD2) in hereditary spastic paraplegia with intellectual disability (SPG54). BMC research notes 19 26113134
2016 Enzymatic characterization of recombinant rat DDHD2: a soluble diacylglycerol lipase. Journal of biochemistry 16 27198176
2025 DDHD2 provides a flux of saturated fatty acids for neuronal energy and function. Nature metabolism 15 41028912
2024 DDHD2, whose mutations cause spastic paraplegia type 54, enhances lipophagy via engaging ATG8 family proteins. Cell death and differentiation 15 38332048
2023 Cooperative lipolytic control of neuronal triacylglycerol by spastic paraplegia-associated enzyme DDHD2 and ATGL. Journal of lipid research 13 37832604
2024 Radiation-Induced Endothelial Ferroptosis Accelerates Atherosclerosis via the DDHD2-Mediated Nrf2/GPX4 Pathway. Biomolecules 7 39062593
2023 Biallelic DDHD2 mutations in patients with adult-onset complex hereditary spastic paraplegia. Annals of clinical and translational neurology 6 37420318
2020 DDHD1, but Not DDHD2, Suppresses Neurite Outgrowth in SH-SY5Y and PC12 Cells by Regulating Protein Transport From Recycling Endosomes. Frontiers in cell and developmental biology 5 32850804
2024 DDHD2 promotes lipid droplet catabolism by acting as a TAG lipase and a cargo receptor for lipophagy. Autophagy 4 38909316
2025 DDHD2 possesses both lipase and transacylase capacities that remodel triglyceride acyl chains. Proceedings of the National Academy of Sciences of the United States of America 3 41264248
2022 Case report: Novel compound heterozygous missense mutations in the DDHD2 gene in a Chinese patient associated with spastic paraplegia type 54. Frontiers in pediatrics 3 36090575
2020 Coinheritance of novel mutations in NAGLU causing mucopolysaccharidosis type IIIB and in DDHD2 causing spastic paraplegia54 in a Turkish family. Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia 2 33246910
2025 Acute lipid droplet accumulation induced by the inhibition of the phospholipase DDHD2 does not affect the level, solubility, or phosphoserine-129 status of α-synuclein. Metabolic brain disease 0 39853540
2025 DDHD2 possesses both lipase and transacylase capacities that remodel triglyceride acyl chains. bioRxiv : the preprint server for biology 0 41040251