Affinage

THEM4

Acyl-coenzyme A thioesterase THEM4 · UniProt Q5T1C6

Length
240 aa
Mass
27.1 kDa
Annotated
2026-06-10
25 papers in source corpus 19 papers cited in narrative 19 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

THEM4 (CTMP) is a mitochondrial protein that acts as an endogenous negative regulator of PKB/Akt signaling by binding the carboxyl-terminal regulatory domain of Akt and suppressing its phosphorylation at both Ser473 and Thr308, thereby reverting Akt-driven transformation (PMID:11598301). It resides in the mitochondrial inter-membrane space as both membrane-bound and free pools, and upon apoptotic stimulation is released to the cytosol where it amplifies mitochondrial depolarization and caspase-3/PARP cleavage; a mitochondrially retained mutant loses this pro-apoptotic activity, coupling its subcellular release to cell-death sensitization (PMID:19168129). Independent of apoptosis, THEM4 governs mitochondrial morphology, promoting fission-like clustering when present and yielding swollen, interconnected mitochondria when depleted, a phenotype confirmed in knockout mouse liver (PMID:19421406). Through its Akt-inhibitory function THEM4 shapes injury and disease responses: it is induced in vulnerable neurons during cerebral ischemia and traumatic brain injury, where its depletion restores Akt activity and rescues neurons or improves recovery (PMID:19349976, PMID:24670215, PMID:27161366), and it regulates Akt-dependent protein synthesis versus ubiquitin-ligase catabolism in skeletal muscle, with its loss mitigating denervation-induced atrophy (PMID:36652767). THEM4 expression and protein levels are controlled by an ATF3/NF-κB transcriptional axis (PMID:24771044), by miR-183-5p (PMID:34249713), and by PRAME-directed Cul2 E3 ligase ubiquitination and proteasomal degradation (PMID:39071619), while its interaction with LETM1 modulates its Akt-suppressing output (PMID:24333006, PMID:23392203). A high-affinity interaction with REV7 extends THEM4 function beyond Akt, driving CDK1-dependent G2/M progression and suppressing HLA-B/MHC-I antigen presentation, positioning it at a nexus linking Akt activity, mitochondrial homeostasis, cell cycle, and immune evasion (PMID:42143164).

Mechanistic history

Synthesis pass · year-by-year structured walk · 10 steps
  1. 2001 High

    Established THEM4/CTMP as a direct, physiological negative regulator of Akt, defining its founding molecular function.

    Evidence Binding assays, kinase and phosphorylation assays, and reversion of v-Akt transformation

    PMID:11598301

    Open questions at the time
    • Did not resolve where in the cell the inhibitory interaction predominates
    • Structural basis of binding to the Akt C-terminal domain not defined
  2. 2009 High

    Resolved THEM4's mitochondrial localization and showed its apoptotic release from the inter-membrane space is required for pro-apoptotic activity, linking compartmentalization to function.

    Evidence Subcellular fractionation, live-cell imaging, mitochondrial membrane potential and caspase assays, retention mutant, RNAi

    PMID:19168129

    Open questions at the time
    • Mechanism of release from mitochondria not defined
    • Relationship between mitochondrial pool and plasma-membrane Akt inhibition unclear
  3. 2009 High

    Demonstrated a distinct role for THEM4 in controlling mitochondrial fission/morphology, separating this from its apoptotic function.

    Evidence Fluorescence microscopy of mitochondrial morphology, RNAi, cleavage-resistant mutant overexpression, CTMP-KO mouse liver

    PMID:19421406

    Open questions at the time
    • Molecular fission machinery engaged by THEM4 not identified
    • Whether morphology control requires Akt inhibition is unresolved
  4. 2009 High

    Showed THEM4 inhibition of Akt is functionally consequential in vivo, where its induction kills ischemic neurons and its depletion is protective.

    Evidence Rat global ischemia model, co-IP, kinase assays, downstream GSK-3β/FOXO3A readouts, lentiviral RNAi rescue; cell-permeable TAT-CTMP peptide in pancreatic cancer xenografts

    PMID:19349976 PMID:19405118

    Open questions at the time
    • Upstream signal triggering THEM4 induction in ischemia not fully defined
    • Peptide tumor-selectivity mechanism not dissected
  5. 2014 High

    Identified the transcriptional control of THEM4 through competing ATF3 repression and NF-κB activation at its promoter, explaining its injury-induced expression.

    Evidence Reporter and ChIP assays, ATF3-VP16 and degradation-resistant IκBα constructs, siRNA, p-Akt readouts; TBI knockdown model with functional scoring

    PMID:24670215 PMID:24771044

    Open questions at the time
    • Signals selecting ATF3 versus NF-κB occupancy not defined
    • Generality of this axis beyond neural injury untested
  6. 2013 Medium

    Placed THEM4 in a metabolic/oncogenic Akt context and identified LETM1 as a binding partner that modulates THEM4's Akt-suppressing output.

    Evidence Overexpression in HEK293 and obese mouse adipose tissue; co-IP and co-delivery of LETM1/CTMP in an HCC mouse model with phosphorylation and apoptosis readouts

    PMID:23392203 PMID:24333006

    Open questions at the time
    • Mechanism by which LETM1 antagonizes or directs THEM4 not defined
    • Direct versus indirect LETM1–THEM4 binding not fully characterized
  7. 2016 Medium

    Extended THEM4 regulation to diabetic and excitotoxic injury and raised the possibility of phosphorylation-dependent biphasic control of its activity.

    Evidence db/db focal ischemia model with siRNA rescue and infarct measurement; kainic acid model and primary astrocyte LPS/IFN-γ stimulation tracking p-CTMP/p-Akt/p-CREB

    PMID:27161366 PMID:28243164

    Open questions at the time
    • The p-CTMP phosphosite and responsible kinase were not directly manipulated
    • Astrocyte data are correlative without mechanistic perturbation
  8. 2022 Medium

    Documented post-transcriptional and proteostatic control of THEM4 abundance and embedded it in cancer signaling networks.

    Evidence miR-183-5p target validation with rescue in colon cancer; LETM1-silencing epistasis in endometrial cancer; PRAME/Cul2 co-IP and ubiquitination assays in myeloma

    PMID:34249713 PMID:35324530 PMID:39071619

    Open questions at the time
    • Context-dependence of these regulators across tissues unresolved
    • Whether THEM4 degradation kinetics directly set Akt output not quantified
  9. 2023 Medium

    Defined THEM4 as a physiological brake on Akt-dependent anabolism and catabolism in skeletal muscle using genetic knockout.

    Evidence CTMP-KO mice with sciatic nerve denervation, Western blot of Akt/GSK3β/S6/4E-BP1 and MuRF-1/myostatin, muscle weight

    PMID:36652767

    Open questions at the time
    • Whether muscle phenotype is cell-autonomous to myofibers not established
    • Mitochondrial contribution in muscle not examined
  10. 2026 Medium

    Discovered a high-affinity THEM4–REV7 interaction that couples THEM4 to CDK1-driven cell cycle progression and MHC-I/antigen-presentation control, expanding its role into immune evasion.

    Evidence IP-mass spectrometry, co-IP, GST pulldown with truncation/point mutants, AlphaFold Multimer, CTMP KD/OE in vitro and syngeneic mouse model, cell cycle and CD8+ T cell flow cytometry, HLA-B/AKT/PD-L1 readouts

    PMID:42143164

    Open questions at the time
    • Whether REV7 binding is mechanistically separable from Akt regulation unclear
    • cGAS-dependent HLA-B restoration pathway not fully dissected
    • Single lab; reciprocal validation in other tumor types pending

Open questions

Synthesis pass · forward-looking unresolved questions
  • How THEM4's mitochondrial residence, its release to the cytosol, and its direct Akt and REV7 interactions are mechanistically integrated into a single regulatory logic remains unresolved.
  • No structure of the THEM4–Akt complex
  • Trigger and machinery for mitochondrial release not defined
  • Whether Akt-inhibitory and REV7/cell-cycle functions are independent or coupled is unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0098772 molecular function regulator activity 3 GO:0140096 catalytic activity, acting on a protein 1
Localization
GO:0005739 mitochondrion 2 GO:0005829 cytosol 1 GO:0005886 plasma membrane 1
Pathway
R-HSA-162582 Signal Transduction 2 R-HSA-5357801 Programmed Cell Death 2 R-HSA-1640170 Cell Cycle 1
Partners
AKT1CAMK2ACARD9LETM1PRAMEREV7

Evidence

Reading pass · 19 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2001 CTMP (THEM4) binds specifically to the carboxyl-terminal regulatory domain of PKBα/Akt at the plasma membrane, reducing PKBα activity by inhibiting phosphorylation on both Ser473 and Thr308. CTMP expression also reverts the transformed phenotype of v-Akt-transformed cells. Protein binding assays (pull-down/co-IP), kinase activity assays, phosphorylation analysis, cell morphology/growth/tumorigenesis assays Science High 11598301
2009 CTMP (THEM4) localizes to mitochondria with a dual sub-mitochondrial distribution (membrane-bound pool and free pool in the inter-membrane space), is released into the cytosol early upon apoptosis induction, and overexpression sensitizes cells to apoptosis by increasing mitochondrial membrane depolarization and caspase-3/PARP cleavage. A CTMP mutant retained in mitochondria loses pro-apoptotic function. CTMP knockdown reduces mitochondrial membrane potential loss and caspase-3/PARP activation. CTMP also delays PKB phosphorylation following cell death induction. Subcellular fractionation, live-cell imaging, mitochondrial membrane potential assays, caspase-3/PARP cleavage assays, RNAi knockdown, CTMP retention mutant Cellular signalling High 19168129
2009 CTMP (THEM4) overexpression or depletion regulates mitochondrial dynamics: both full-length CTMP and a cleavage-resistant mutant promote clustering of spherical mitochondria (consistent with increased fission), while CTMP depletion leads to accumulation of swollen, interconnected mitochondria without affecting fusion. CTMP knockout mouse liver mitochondria phenocopy the depletion phenotype. Fluorescence microscopy (mitochondrial morphology), RNAi knockdown, CTMP mutant overexpression, CTMP knockout mouse liver analysis PloS one High 19421406
2009 In global cerebral ischemia, CTMP (THEM4) expression and activation is induced in vulnerable hippocampal neurons; CTMP binds Akt and extinguishes its activity despite nuclear translocation and phosphorylation of Akt. RNAi-mediated depletion of CTMP in a stroke model restored Akt activity (assessed by kinase assays and phosphorylation of GSK-3β and FOXO3A) and rescued hippocampal neurons from ischemia-induced death. In vivo rat ischemia model, co-immunoprecipitation, kinase assays, phosphorylation of downstream targets (GSK-3β, FOXO3A), lentiviral RNAi, histological neuronal survival assessment Nature neuroscience High 19349976
2009 A cell-permeable peptide from the N-terminal domain of CTMP (TAT-CTMP4) induces dose-dependent apoptosis (caspase-3 activation) selectively in pancreatic adenocarcinoma cell lines and xenografts, and augments gemcitabine and radiation therapy in vivo, placing CTMP-mediated Akt inhibition upstream of caspase-3-dependent apoptosis. Cell-permeable peptide treatment, TUNEL assay, active caspase-3 measurement, xenograft and allograft tumor models International journal of cancer Medium 19405118
2013 CTMP (THEM4) overexpression suppresses insulin-induced PKB/Akt phosphorylation in HEK293 cells, and in obese mouse adipose tissue CTMP levels are elevated while phospho-PKB is reduced. Co-overexpression of LETM1 abrogates the CTMP-mediated suppression of PKB phosphorylation, suggesting LETM1 acts downstream of PKB activation to antagonize CTMP. Transient transfection, adenovirus-mediated overexpression, Western blot in HEK293 cells, Western blot/immunohistochemistry in HFD and ob/ob mouse models Metabolism: clinical and experimental Medium 24333006
2013 In a hepatocellular carcinoma mouse model, CTMP (THEM4) acts as a direct binding partner of Akt1, and LETM1 acts as a binding partner of CTMP. Co-delivery of LETM1 and CTMP downregulated Akt1 pathway phosphorylation at both Ser473 and Thr308, induced mitochondrial morphological changes (swelling, loss of cristae), and triggered mitochondria-mediated apoptosis, reducing tumor incidence. Co-immunoprecipitation (binding partners), Western blot (Akt phosphorylation), in vivo HCC model (H-ras12V mice), gross/microscopic tumor evaluation Cancer gene therapy Medium 23392203
2014 ATF3 transcriptionally represses CTMP expression in hypoxic neurons by binding to the ATF/CREB site in the CTMP promoter and blocking NF-κB binding, which otherwise activates CTMP transcription. This ATF3→CTMP cascade regulates neuronal apoptosis via Akt pathway modulation. Reporter assays, ChIP assays, gain- and loss-of-function experiments, ATF3-VP16 fusion (converted to activator), degradation-resistant IκBα, siRNA knockdown, p-Akt (Ser473) measurement Molecular neurobiology High 24771044
2014 In a mouse traumatic brain injury (TBI) model, CTMP expression increases significantly after injury and correlates with inhibition of Akt phosphorylation. siRNA-mediated knockdown of CTMP augments Akt phosphorylation and significantly improves neurological recovery over 28 days post-TBI. Controlled cortical impact TBI model, immunohistochemistry, Western blot (phospho-Akt/CTMP), intracranial siRNA injection, neurological functional scoring Neurological research Medium 24670215
2016 In excitotoxic kainic acid-induced neurodegeneration, CTMP is markedly upregulated in hippocampal astrocytes. LPS/IFN-γ treatment of primary astrocytes induces early phosphorylation of CTMP (p-CTMP) followed by Akt and CREB phosphorylation, with later CTMP upregulation inhibiting Akt activity, suggesting a biphasic regulatory role of CTMP phosphorylation in Akt/CREB signaling in astrocytes. In vivo kainic acid mouse model, immunohistochemistry, Western blot (p-CTMP, p-Akt, p-CREB, CTMP), primary astrocyte culture with LPS/IFN-γ treatment Experimental neurobiology Low 28243164
2016 In diabetic db/db mice with focal cerebral ischemia, CTMP expression is constitutively elevated, leading to decreased Akt kinase activity and worse neurological outcomes compared to non-diabetic controls. RNAi-mediated depletion of CTMP in db/db mice restores Akt activity, improves neurological scores, and reduces infarct volume. db/db mouse model, Western blot (CTMP, Akt activity), siRNA injection, PI3K inhibitor (LY294002) treatment, neurological scoring, infarct volume measurement Neurochemical research Medium 27161366
2021 miR-183-5p directly targets THEM4, inhibiting its mRNA and protein expression. Overexpression of THEM4 abrogates miR-183-5p-mediated oncogenic effects and inactivates Akt and NF-κB pathways in colon cancer cells, placing THEM4 as an upstream negative regulator of both Akt and NF-κB in this context. Luciferase/target validation of miR-183-5p→THEM4, Western blot (Akt, NF-κB), THEM4 overexpression rescue, CCK-8, colony formation, Transwell, xenograft assays Frontiers in oncology Medium 34249713
2022 LETM1 silencing downregulates CTMP in endometrial cancer cells (KLE), and CTMP overexpression rescues the suppressed malignant phenotype (viability, migration, invasion) caused by LETM1 silencing, placing CTMP downstream of LETM1 in endometrial cancer progression. siRNA knockdown of LETM1 and CTMP, CTMP overexpression rescue, Western blot, CCK-8, colony formation, wound healing, Transwell, xenograft model Anti-cancer drugs Medium 35324530
2023 CTMP (THEM4) deficiency in CTMP-KO mice mitigates denervation-induced skeletal muscle atrophy after sciatic nerve injury: CTMP-KO gastrocnemius shows higher Akt, GSK3β, S6, and 4E-BP1 phosphorylation and lower MuRF-1 and myostatin levels compared to wild-type, establishing CTMP as a regulator of Akt-dependent protein synthesis and ubiquitin-ligase-mediated catabolism in muscle. CTMP knockout mice, sciatic nerve injury model, Western blot (Akt, GSK3β, S6, 4E-BP1, MuRF-1, myostatin phosphorylation/expression), muscle weight measurement Biochemical and biophysical research communications Medium 36652767
2024 PRAME, acting as a substrate-recognizing subunit of a Cul2-dependent E3 ubiquitin ligase, interacts with CTMP and p21, mediating their ubiquitination and proteasomal degradation. This leads to accumulation of phospho-Akt and CCND3, promoting proliferation in multiple myeloma cells. Co-immunoprecipitation (PRAME–CTMP interaction), ubiquitination assays, PRAME knockdown/overexpression, Western blot (p-Akt, CTMP, p21, CCND3), proliferation assays Heliyon Medium 39071619
2024 CARD9 interacts with THEM4 in cholangiocarcinoma cells, and this interaction facilitates AKT and mTOR phosphorylation, promoting CCA cell proliferation and invasion. Co-immunoprecipitation or interaction assay (CARD9–THEM4), Western blot (AKT, mTOR phosphorylation), gain/loss-of-function in CCA cell lines and nude mouse models International immunopharmacology Low 39418733
2025 CAMK2A facilitates THEM4 release from mitochondria in pancreatic ductal adenocarcinoma cells. Released THEM4 inhibits AKT phosphorylation and suppresses PDAC tumor growth; THEM4 knockdown accelerates in vivo tumor growth. Functional experiments (mitochondrial membrane potential, ATP, ROS assays), THEM4 KD and xenograft tumor growth, AKT phosphorylation Western blot, immunohistochemical microarray Journal of translational medicine Low 41353164
2025 CTMP knockdown enhances sensitivity of endometrial cancer cells to medroxyprogesterone acetate (MPA) by suppressing the PI3K/AKT signaling pathway, as assessed by cell proliferation assays and Western blot of PI3K/AKT pathway proteins. siRNA knockdown of CTMP, Western blot (PI3K/AKT pathway proteins), CCK-8, EDU incorporation assay, immunohistochemistry in clinical samples Reproductive sciences Low 41201690
2026 In MSI-L/MSS colorectal cancer, CTMP interacts with REV7 (a novel high-affinity interaction identified by immunoprecipitation-mass spectrometry and validated by co-IP, GST pulldown with truncation/point mutants, and AlphaFold Multimer structural modeling). This CTMP–REV7 interaction facilitates CDK1-mediated G2/M progression and suppresses HLA-B/MHC-I expression. CTMP also sustains AKT/PD-L1 signaling and promotes fatty acid metabolism. CTMP knockdown diminishes CDK1 activity, induces G2/M arrest, restores HLA-B expression via cGAS signaling, enhances CD8+ T cell infiltration, and synergizes with REV7 overexpression and IFN-γ. Immunoprecipitation-mass spectrometry, co-IP, GST pulldown with truncation/point mutants, AlphaFold Multimer, CTMP KD/OE (in vitro and syngeneic mouse model), cell cycle analysis, flow cytometry (CD8+ T cells), HLA-B/MHC-I expression assays, AKT/PD-L1 Western blot Cellular oncology Medium 42143164

Source papers

Stage 0 corpus · 25 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2001 Carboxyl-terminal modulator protein (CTMP), a negative regulator of PKB/Akt and v-Akt at the plasma membrane. Science (New York, N.Y.) 205 11598301
2009 The endogenous inhibitor of Akt, CTMP, is critical to ischemia-induced neuronal death. Nature neuroscience 97 19349976
2006 Activation of Akt independent of PTEN and CTMP tumor-suppressor gene mutations in epilepsy-associated Taylor-type focal cortical dysplasias. Acta neuropathologica 48 17013611
2021 Exosomal miR-183-5p Shuttled by M2 Polarized Tumor-Associated Macrophage Promotes the Development of Colon Cancer via Targeting THEM4 Mediated PI3K/AKT and NF-κB Pathways. Frontiers in oncology 47 34249713
2009 Targeting AKT with the proapoptotic peptide, TAT-CTMP: a novel strategy for the treatment of human pancreatic adenocarcinoma. International journal of cancer 44 19405118
2009 Carboxy-Terminal Modulator Protein (CTMP) is a mitochondrial protein that sensitizes cells to apoptosis. Cellular signalling 34 19168129
2014 Novel link of anti-apoptotic ATF3 with pro-apoptotic CTMP in the ischemic brain. Molecular neurobiology 27 24771044
2013 New players in high fat diet-induced obesity: LETM1 and CTMP. Metabolism: clinical and experimental 20 24333006
2017 CTMP, a predictive biomarker for trastuzumab resistance in HER2-enriched breast cancer patient. Oncotarget 19 27447863
2021 Abiotic Synthesis of Nucleoside 5'-Triphosphates with Nickel Borate and Cyclic Trimetaphosphate (CTMP). Astrobiology 18 33533695
2009 The Carboxy-Terminal Modulator Protein (CTMP) regulates mitochondrial dynamics. PloS one 17 19421406
2013 Co-delivery of LETM1 and CTMP synergistically inhibits tumor growth in H-ras12V liver cancer model mice. Cancer gene therapy 16 23392203
2022 Effect of different iodine levels on the DNA methylation of PRKAA2, ITGA6, THEM4 and PRL genes in PI3K-AKT signaling pathway and population-based validation from autoimmune thyroiditis patients. European journal of nutrition 15 35622138
2014 Small interfering RNA directed against CTMP reduces acute traumatic brain injury in a mouse model by activating Akt. Neurological research 11 24670215
2016 Elevated Expression of Carboxy-Terminal Modulator Protein (CTMP) Aggravates Brain Ischemic Injury in Diabetic db/db Mice. Neurochemical research 6 27161366
2016 Astrocytic Expression of CTMP Following an Excitotoxic Lesion in the Mouse Hippocampus. Experimental neurobiology 6 28243164
2023 Carboxyl-terminal modulator protein (CTMP) deficiency mitigates denervation-induced skeletal muscle atrophy. Biochemical and biophysical research communications 5 36652767
2022 Mitochondrial protein LETM1 and its-mediated CTMP are potential therapeutic targets for endometrial cancer. Anti-cancer drugs 5 35324530
2018 In Vitro Neurochemical Assessment of Methylphenidate and Its "Legal High" Analogs 3,4-CTMP and Ethylphenidate in Rat Nucleus Accumbens and Bed Nucleus of the Stria Terminalis. Frontiers in psychiatry 5 29892233
2024 Roles of THEM4 in the Akt pathway: a double-edged sword. Journal of Zhejiang University. Science. B 3 39011675
2024 PRAME promotes proliferation of multiple myeloma cells through CTMP/Akt/p21/CCND3 axis by ubiquitinating CTMP and p21. Heliyon 2 39071619
2024 CARD9 promotes cholangiocarcinoma by regulating the IL-17A/Hedgehog and the THEM4/AKT/mTOR signaling pathways. International immunopharmacology 2 39418733
2026 CTMP-REV7 axis modulates MHC-I antigen presentation via CDK1-AKT crosstalk in MSI-L/MSS colorectal cancer. Cellular oncology (Dordrecht, Netherlands) 0 42143164
2025 Knockdown of CTMP Enhances Progesterone Sensitivity in Endometrial Cancer by Inhibiting the PI3K/AKT Signaling Pathway. Reproductive sciences (Thousand Oaks, Calif.) 0 41201690
2025 A mitochondria-related gene-based signature predicts pancreatic ductal adenocarcinoma clinical outcome and revealed CAMK2A/THEM4 regulates progression phenotypes and mitophagy in vivo and in vitro. Journal of translational medicine 0 41353164

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