Induction of Yin Yang 1 (YY1) overexpression in mature adipocytes promotes dysfunctional adipose tissue and systemic insulin resistance in mice

The ubiquitous transcription factor Ying Yang 1 (YY1) plays a fundamental role in multiple biological processes and is believed to regulate up to 10 % of all human genes. In thermogenic brown adipose tissue, YY1 has been linked to controlling mitochondrial gene expression and regulating cellular oxidative respiration, protecting against diet-induced obesity and alterations in energy balance. The role of YY1 in non-thermogenic, white adipose tissue, on the other hand, remains largely unknown. Here, we show that adipocyte-specific induction of YY1 promotes dysfunctional adipose tissue and systemic insulin resistance in mice. Long-term YY1 induction in mature adipocytes leads to reduced weight gain, systemic insulin resistance, and increased liver steatosis in comparison to control littermates. In contrast, brown adipose tissue-specific YY1 overexpression has little effect on mice fed a high-fat diet. In an obesogenic environment, acute ectopic adiponectin promoter-driven YY1 expression promotes weight loss, cell death, and adipose tissue inflammation. Underlying the observed reduction in adipose tissue mass, we find that YY1 controls gene networks related to adipose tissue expansion, lipid anabolic pathways (hypertrophy), and hyperplasia (adipogenesis). Taken together, our results demonstrate novel roles of Yy1 in white adipose tissue. This versatile transcription factor regulates central aspects of white adipose tissue biology that are essential for maintaining whole-body physiology.