TGFβ-dependent upregulation of OCIAD2 is essential for epithelial-to-mesenchymal transition during mesendoderm differentiation

Deciphering mechanisms that govern lineage commitment of human pluripotent stem cells (hPSCs) is essential for optimizing differentiation strategies. Here, we investigated the role of the mitochondrial protein OCIAD2 in hPSC differentiation. We show that OCIAD2 is transiently upregulated during mesendoderm differentiation, in a TGF{beta}/Activin A-dependent manner. OCIAD2 depletion impairs mesendoderm induction and specification, resulting in an incomplete epithelial-to-mesenchymal transition (EMT). Through transcriptome analysis, immunoblotting and localization studies on OCIAD2-depleted (KO) or overexpressing (OV) human embryonic stem cells (hESCs), we identified OCIAD2 as a positive regulator of TGF{beta} signalling. Additionally, KO hESCs exhibited downregulated fatty acid oxidation (FAO) genes, indicating dysregulated lipid metabolism. Pharmacological restoration of FAO improved mesendoderm differentiation capacity in KO, suggesting a key role for OCIAD2 in coordinating metabolism and TGF{beta} signalling. We propose that OCIAD2 regulates EMT by integrating metabolic cues with TGF{beta} pathway activation. Our findings provide insight into how mitochondrial proteins regulate lineage commitment and EMT, with broader implications for both developmental biology and tumor progression. HighlightsO_LIOCIAD2 expression peaks during mesendoderm specification of hESCs C_LIO_LIOCIAD2 depletion transcriptionally represses TGF{beta} signalling and impedes EMT C_LIO_LILoss of OCIAD2 leads to hyperfused mitochondria and downregulation of FAO genes C_LIO_LIPharmacologic supplementation with acetate enhances mesendoderm specification C_LI