Terminal differentiation opposes proliferation in the vast majority of tissue types. As a result, loss of lineage differentiation is a hallmark of aggressive cancers, including soft tissue sarcomas (STS). Consistent with these observations, undifferentiated pleomorphic sarcoma (UPS), an STS subtype devoid of lineage markers, is among the most lethal sarcomas in adults. Though tissue-specific features are lost in these mesenchymal tumors they are most commonly diagnosed in skeletal muscle, and are thought to develop from transformed muscle progenitor cells. We have found that a combination of HDAC (Vorinostat) and BET bromodomain (JQ1) inhibition partially restores differentiation to skeletal muscle UPS cells and tissues, enforcing a myoblast-like identity. Importantly, differentiation is partially contingent upon downregulation of the Hippo pathway transcriptional effector Yes-associated protein 1 (YAP1) and nuclear factor (NF)-κB. Previously, we observed that Vorinostat/JQ1 inactivates YAP1 and restores oscillation of NF-κB in differentiating myoblasts. These effects correlate with reduced tumorigenesis, and enhanced differentiation. However, the mechanisms by which the Hippo/NF-κB axis impact differentiation remained unknown. Here, we report that YAP1 and NF-κB activity suppress circadian clock function, inhibiting differentiation and promoting proliferation. In most tissues, clock activation is antagonized by the unfolded protein response (UPR). However, skeletal muscle differentiation requires both Clock and UPR activity, suggesting the molecular link between them is unique in muscle. In skeletal muscle-derived UPS, we observed that YAP1 suppresses PERK and ATF6-mediated UPR target expression as well as clock genes. These pathways govern metabolic processes, including autophagy, and their disruption shifts metabolism toward cancer cell-associated glycolysis and hyper-proliferation. Treatment with Vorinostat/JQ1 inhibited glycolysis/MTOR signaling, activated the clock, and upregulated the UPR and autophagy via inhibition of YAP1/NF-κB. These findings support the use of epigenetic modulators to treat human UPS. In addition, we identify specific autophagy, UPR, and muscle differentiation-associated genes as potential biomarkers of treatment efficacy and differentiation.

Highlights d Adipocyte EBF2 maintains BAT thermogenic character and function under basal conditions d EBF1 or EBF2 is required for chronic cold-induced BAT recruitment d EBF1 or EBF2 cooperate with ERRa and PGC1a to promote Ucp1 transcription d EBF activity controls basal and adaptive thermogenic gene programing in adipocytes

Highlights d In mouse brown fat, PPARa shares its genomic binding sites with PPARg d Common PPARa/g targets identify brown fat function better than PPARg alone d Candidate brown fat genes are induced by PPARa and PPARg agonists and by cold d CTSZ is necessary for full respiration in mouse and human brown adipocytes

Highlights d Hepatic AKT is activated in response to cold exposure and b 3 adrenergic stimulation d Lack of AKT in liver leads to cold sensitivity d Hepatic AKT signaling via FOXO1 induces FGF21 expression d FOXO1 cell-nonautonomously regulates adipose tissue thermogenesis