ECHDC2

ECHDC2 is a mitochondrial protein linked to branched-chain amino acid and fatty acid metabolism that modulates cellular survival and proliferation across cardiac and cancer contexts (PMID:24108764, PMID:31437751). In cardiomyocytes, ECHDC2 localizes to mitochondria, and its level sets susceptibility to ischemia/reperfusion injury—overexpression sensitizes cells while knockdown confers resistance—accompanied by elevated branched-chain amino acids leucine and valine without measurable changes in oxygen consumption or ATP production (PMID:24108764). In gastric cancer, ECHDC2 binds the E3 ubiquitin ligase NEDD4 and promotes ubiquitination and proteasomal degradation of MCCC2, thereby suppressing P38 MAPK signaling, aerobic glycolysis, and tumor cell proliferation in vitro and in xenografts (PMID:38783226). ECHDC2 is also required for anoikis escape and suspension growth of high-grade serous ovarian cancer cells, consistent with a role downstream of fatty acid metabolism (PMID:31437751). Beyond these contexts and the NEDD4–MCCC2 axis, no enzymatic substrate or structural mechanism for ECHDC2 has been characterized in the available corpus.

1. 2013 Medium

   Established ECHDC2 as a mitochondrial protein whose abundance bidirectionally controls cardiomyocyte vulnerability to ischemia/reperfusion injury and influences branched-chain amino acid levels.

   Evidence Subcellular fractionation/IHC localization, gain- and loss-of-function with I/R injury assay, and GC-MS metabolomics in cardiomyocytes

   PMID:24108764

   Open questions at the time

   • The enzymatic activity of ECHDC2 on BCAA or fatty acid intermediates was not directly demonstrated
   • Mechanism linking ECHDC2 to I/R susceptibility unresolved despite no change in O2 consumption or ATP
   • No in vivo cardiac model beyond cellular assays
2. 2019 Medium

   Identified ECHDC2 as a fatty-acid-metabolism effector required for anoikis escape, extending its role from cardiac biology to cancer cell survival in suspension.

   Evidence Genome-wide CRISPR/Cas9 screen with siRNA validation, suspension growth assay, and non-targeted metabolomics in ovarian cancer cells

   PMID:31437751

   Open questions at the time

   • The metabolic substrate of ECHDC2 driving suspension survival was not defined
   • No reciprocal rescue or overexpression to confirm specificity
   • Connection to a defined signaling pathway not established
3. 2024 Medium

   Defined a molecular mechanism for ECHDC2's tumor-suppressive action: recruitment of NEDD4 to drive MCCC2 degradation, dampening P38 MAPK signaling and aerobic glycolysis.

   Evidence Reciprocal co-immunoprecipitation, ubiquitination and Western assays, glucose/lactate measurements, and subcutaneous xenografts in gastric cancer

   PMID:38783226

   Open questions at the time

   • Whether ECHDC2 directly recruits NEDD4 or acts as an adaptor versus enzyme is not resolved
   • Single lab without independent replication
   • Reconciliation with pro-survival roles in ovarian/glioblastoma contexts not addressed
4. 2026 Low

   Showed that, in contrast to its gastric tumor-suppressive role, ECHDC2 promotes proliferation and migration of glioblastoma cells, associating it with PI3K/Akt signaling.

   Evidence siRNA knockdown and overexpression with proliferation/migration assays and GSEA/KEGG enrichment in GBM cell lines

   PMID:41732157

   Open questions at the time

   • PI3K/Akt placement rests on bioinformatic enrichment without direct pathway validation
   • Context-dependent opposing roles across cancers mechanistically unexplained
   • No in vivo confirmation
5. 2025 Low

   Provided correlative in vivo evidence linking ECHDC2 abundance to mitochondrial β-oxidation by showing high-dose vitamin D3 downregulates hepatic ECHDC2.

   Evidence Integrative transcriptomic and quantitative proteomic analysis of pig liver tissue

   PMID:40680899

   Open questions at the time

   • Protein-level change observed without any direct functional test of ECHDC2
   • Causal relationship between vitamin D3 and ECHDC2 not established
   • β-oxidation role inferred, not measured

• The direct biochemical activity of ECHDC2 and how it produces opposing proliferative outcomes across tissues remain unknown.
• No defined catalytic substrate or reaction for ECHDC2
• Mechanism reconciling tumor-suppressor (gastric) versus pro-tumor (GBM) roles unresolved
• No structural model or domain-level mechanism of NEDD4/MCCC2 engagement