Taejun Seol

Adipocyte differentiation from mesenchymal stem cells is governed by tightly regulated transcriptional and epigenetic programs. The Hippo pathway effectors YAP and TAZ impede this process, yet the underlying molecular mechanisms remain unclear. Here, we demonstrate how YAP/TAZ regulate transcription of the adipocyte lineage specification factor PPARγ and its target genes at the chromatin level. TAZ represses PPARγ-bound target enhancers as evidenced by a markedly reduced histone H3 acetylated at lysine-27 occupancy, resulting in the transcriptional repression of adipogenic genes, including Pparg2 . Single-nucleus genomic analyses of mouse adipose tissue further revealed that YAP/TAZ activation drives extensive epigenetic modulation. Notably, the repressive effect of TAZ on adipogenic enhancers requires TEAD-dependent transcriptional activity, but not a direct interaction with PPARγ through the WW domain as previously reported. Last, we identified Vestigial-like 3 ( Vgll3 ) as a transcriptional target of TAZ critical for repressing adipogenic enhancers. These findings reveal that the YAP/TAZ-VGLL3 axis regulates adipocyte fate by repressing the PPARγ program at its target enhancers.

Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ) play fundamental roles in stem/progenitor cell expansion during homeostasis, and their dysregulation often leads to tissue overgrowth. Here, we show that YAP activation is sufficient to overcome the restriction of global protein synthesis induced by serum starvation, enabling cells to sustain proliferation and survival despite an unfavorable environment. Mechanistically, YAP/TAZ selectively promoted the mTORC1-dependent translation of mRNAs containing 5′ terminal oligopyrimidine (5′TOP) motifs, ultimately increasing the cellular polysome content. Interestingly, DNA damage-inducible transcript 4 (DDIT4), a negative regulator of mTORC1, was upregulated by serum starvation but repressed by YAP/TAZ. DDIT4 was sufficient to suppress the translation and transformative potential of uveal melanoma cells, which are often serum unresponsive due to G protein mutations. Our findings reveal a vital role for protein synthesis as a key modality of YAP/TAZ-induced oncogenic transformation and indicate the potential for targeting mTORC1 or translation to treat YAP/TAZ-driven malignancies.

Adipose tissues serve as an energy reservoir and endocrine organ, yet the mechanisms that coordinate these functions remain elusive. Here, we show that the transcriptional coregulators, YAP and TAZ, uncouple fat mass from leptin levels and regulate adipocyte plasticity to maintain metabolic homeostasis. Activating YAP/TAZ signalling in adipocytes by deletion of the upstream regulators Lats1 and Lats2 results in a profound reduction in fat mass by converting mature adipocytes into delipidated progenitor-like cells, but does not cause lipodystrophy-related metabolic dysfunction, due to a paradoxical increase in circulating leptin levels. Mechanistically, we demonstrate that YAP/TAZ–TEAD signalling upregulates leptin expression by directly binding to an upstream enhancer site of the leptin gene. We further show that YAP/TAZ activity is associated with, and functionally required for, leptin regulation during fasting and refeeding. These results suggest that adipocyte Hippo–YAP/TAZ signalling constitutes a nexus for coordinating adipose tissue lipid storage capacity and systemic energy balance through the regulation of adipocyte plasticity and leptin gene transcription.