Adipocytes are the defining cell type of adipose tissue. Once considered a passive participant in energy storage, adipose tissue is now recognized as a dynamic organ that contributes to several important physiological processes, such as lipid metabolism, systemic energy homeostasis, and whole-body insulin sensitivity. Therefore, understanding the mechanisms involved in its development and function is of great importance. Adipocyte differentiation is a highly orchestrated process which can vary between different fat depots as well as between the sexes. While hormones, miRNAs, cytoskeletal proteins, and many other effectors can modulate adipocyte development, the best understood regulators of adipogenesis are the transcription factors that inhibit or promote this process. Ectopic expression and knockdown approaches in cultured cells have been widely used to understand the contribution of transcription factors to adipocyte development, providing a basis for more sophisticated in vivo strategies to examine adipogenesis. To date, over two dozen transcription factors have been shown to play important roles in adipocyte development. These transcription factors belong to several families with many different DNA-binding domains. While peroxisome proliferator-activated receptor gamma (PPARγ) is undoubtedly the most important transcriptional modulator of adipocyte development in all types of adipose tissue, members of the CCAAT/enhancer-binding protein, Krüppel-like transcription factor, signal transducer and activator of transcription, GATA, early B cell factor, and interferon-regulatory factor families also regulate adipogenesis. The importance of PPARγ activity is underscored by several covalent modifications that modulate its activity and its ability to modulate adipocyte development. This review will primarily focus on the transcriptional control of adipogenesis in white fat cells and on the mechanisms involved in this fine-tuned developmental process. © 2017 American Physiological Society. Compr Physiol 7:635-674, 2017.

Adipocytes play important roles in lipid storage, energy homeostasis and whole body insulin sensitivity. The JAK-STAT pathway mediates a variety of physiological processes including development, hematopoiesis, and inflammation. Although the JAK-STAT signaling pathway occurs in all cells, this pathway can mediate cell specific responses. Studies in the last two decades have identified hormones and cytokines that activate the JAK-STAT signaling pathway. These cytokines and hormones have profound effects on adipocytes. The content of this review will introduce the types of adipocytes and immune cells that make up adipose tissue, the impact of obesity on adipose cellular composition and function, and the general constituents of the JAK-STAT pathway and how its activators regulate adipose tissue development and physiology. A summary of the identification of STAT target genes in adipocytes reveals how these transcription factors impact various areas of adipocyte metabolism including insulin action, modulation of lipid stores, and glucose homeostasis. Lastly, we will evaluate exciting new data linking the JAK-STAT pathway and brown adipose tissue and consider the future outlook in this area of investigation.

Scope Moringa oleifera (moringa) is tropical plant traditionally used as an antidiabetic food. It produces structurally unique and chemically stable moringa isothiocyanates (MICs) that were evaluated for their therapeutic use in vivo. Methods and results C57BL/6L mice fed very high fat diet (VHFD) supplemented with 5% moringa concentrate (MC, delivering 66 mg/kg/d of MICs) accumulated fat mass, had improved glucose tolerance and insulin signaling, and did not develop fatty liver disease compared to VHFD-fed mice. MC-fed group also had reduced plasma insulin, leptin, resistin, cholesterol, IL-1β, TNFα, and lower hepatic glucose-6-phosphatase (G6P) expression. In hepatoma cells, MC and MICs at low micromolar concentrations inhibited gluconeogenesis and G6P expression. MICs and MC effects on lipolysis in vitro and on thermogenic and lipolytic genes in adipose tissue in vivo argued these are not likely primary targets for the anti-obesity and anti- diabetic effects observed. Conclusion Data suggest that MICs are the main anti-obesity and anti-diabetic bioactives of MC, and that they exert their effects by inhibiting rate-limiting steps in liver gluconeogenesis resulting in direct or indirect increase in insulin signaling and sensitivity. These conclusions suggest that MC may be an effective dietary food for the prevention and treatment of obesity and type 2 diabetes.

Twenty years ago, adipocytes were largely considered inert energy storage depots. Today, we know that fat cells are highly insulin sensitive with significant endocrine functions. Alterations in adipocyte development or function can contribute to metabolic disease, in particular Type 2 diabetes. The current obesity epidemic that plagues many nations provides a strong rationale for understanding basic adipocyte biology. The JAK–STAT signaling pathway mediates the action of a variety of hormones that have profound effects on adipocyte development and function. In addition, adipocytes secrete hormones that utilize this signaling pathway. This review summarizes research on the expression and function of JAKs and STATs in adipocytes and highlights the roles of JAK–STAT-activating cytokines in adipose tissue.