Loss of FAM60A disrupts Sin3/HDAC control of the Hippo signaling and promotes oncogenic YAP1 activation

FAM60A (also known as SINHCAF) is a subunit of the Sin3/HDAC histone deacetylase complex with established roles in chromatin remodeling, yet its broader cellular functions remain largely undefined. Using immunological, biochemical, CRISPR/Cas9, genomic, and proteomic approaches, we mapped the FAM60A interaction network and its functional impact. We reveal that FAM60A binds directly to HDAC1 to recruit Sin3/HDAC, while a dual-domain architecture mediates additional associations with RNA and DNA-binding proteins. CRISPR/Cas9-mediated HDAC1 knockout abolishes the FAM60A-SIN3A interaction, confirming this dependency. Loss of FAM60A triggers widespread transcriptional rewiring, including downregulation of WWC3-a scaffold for LATS1/2 activation. Consequently, YAP1 dephosphorylation and nuclear accumulation shifted cell-cycle dynamics toward G₁ enrichment and conferred resistance to metabolic stress. Restoration of FAM60A or exogenous WWC3 reactivated Hippo "off" signaling, normalized cell-cycle distribution, and reversed stress resistance. These findings establish FAM60A as a pivotal epigenetic tuner linking histone deacetylation to Hippo pathway regulation and nominate the FAM60A-HDAC1-WWC3 axis as a potential therapeutic target to restore growth control in YAP-driven cancers.