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

Deciphering the mechanisms that govern lineage commitment of human pluripotent stem cells (hPSCs) is essential for optimizing differentiation strategies. Here, we uncover the role of the mitochondrial protein OCIAD2 in hPSC fate decisions. We show that OCIAD2 is transiently upregulated during mesendoderm differentiation in response to TGFβ/Activin A signaling. OCIAD2 depletion disrupted TGFβ and WNT signaling, impaired mesendoderm specification, and resulted in an incomplete epithelial-to-mesenchymal transition (EMT). Furthermore, OCIAD2 loss reduced mitochondrial dynamics and fatty acid oxidation, indicating dysregulated lipid metabolism. Transcriptome and biochemical analysis of OCIAD2-knockout (KO) and -overexpressing (OV) hESCs identified OCIAD2 as a positive regulator of TGFβ signaling. Supplementation with acetate alongside Wnt3a increased SMAD2/3 acetylation and restored mesendoderm differentiation in KO. We propose that OCIAD2 integrates metabolic cues with TGFβ signaling to regulate EMT. This study provides new insight into how mitochondrial proteins influence lineage commitment, highlighting broader implications for developmental biology and tumor progression.