MED8 is a subunit of the Mediator complex, a multi-subunit coactivator essential for RNA polymerase II-dependent transcription. MED8 functions as a target recruitment subunit that facilitates transcription factor binding to promoters. In Schizosaccharomyces pombe, MED8 specifically promotes Ace2-dependent transcriptional initiation by enhancing transcription factor recruitment to target promoters through direct physical interaction with Ace2, distinct from other Mediator subunits that maintain complex integrity 1. Beyond canonical transcription regulation, MED8 participates in mitochondrial-cytosolic communication through the Med8/Tfb4-mtSSB/PolG2/mtDNA-helicase axis, mediating extramitochondrial mtDNA replication and activation of immune-like pathways in response to mitochondrial defects 2. MED8 also mediates crosstalk between mitochondrial and lysosomal homeostasis through E(z)/pho signaling 3. In disease contexts, MED8 overexpression correlates with poor prognosis in hepatocellular carcinoma and gastric cancer, where it promotes cell proliferation through G1/S phase transition via Cdk4/CyclinD1 upregulation and enhances sorafenib resistance through stabilization of TRIP4 protein 45. Pathogenic MED8 variants represent part of the emerging MEDopathies spectrum, characterized by neurodevelopmental and neurodegenerative phenotypes including developmental delay and neurological features 6.