EID1 suppresses lipid accumulation by inhibiting the expression of GPDH in 3T3-L1 preadipocytes

Glycerol 3-phosphate dehydrogenases (1 and 2) in cancer and other diseases

The glycerol 3-phosphate shuttle (GPS) is composed of two different enzymes: cytosolic NAD+-linked glycerol 3-phosphate dehydrogenase 1 (GPD1) and mitochondrial FAD-linked glycerol 3-phosphate dehydrogenase 2 (GPD2). These two enzymes work together to act as an NADH shuttle for mitochondrial bioenergetics and function as an important bridge between glucose and lipid metabolism. Since these genes were discovered in the 1960s, their abnormal expression has been described in various metabolic diseases and tumors. Nevertheless, it took a long time until scientists could investigate the causal relationship of these enzymes in those pathophysiological conditions. To date, numerous studies have explored the involvement and mechanisms of GPD1 and GPD2 in cancer and other diseases, encompassing reports of controversial and non-conventional mechanisms. In this review, we summarize and update current knowledge regarding the functions and effects of GPS to provide an overview of how the enzymes influence disease conditions. The potential and challenges of developing therapeutic strategies targeting these enzymes are also discussed.

Endoplasmic reticulum stress and autophagy are involved in adipocyte-induced fibrosis in hepatic stellate cells

Liver fibrosis, with the characterization of progressive accumulation of extracellular matrix (ECM), is the common pathologic feature in the process of chronic liver disease. Hepatic stellate cells (HSCs) which are activated and differentiate into proliferative and contractile myofibroblasts are recognized as the main drivers of fibrosis. Obesity-related adipocytokine dysregulation is known to accelerate liver fibrosis progression, but the direct fibrogenic effect of mature adipocytes on HSCs has been rarely reported. Therefore, the purpose of this study was to explore the fibrogenic effect of adipocyte 3T3-L1 cells on hepatic stellate LX-2 cells. The results showed that incubating LX-2 cells with the supernatant of 3T3-L1 adipocytes triggered the expression of ECM related proteins, such as α-smooth muscle actin (α-SMA), type I collagen (CO-I), and activated TGF β/Smad2/3 signaling pathway in LX-2 cells. In addition, 3T3-L1 cells inhibited insulin sensitivity, activated endoplasmic reticulum stress and autophagy to promote the development of fibrosis. These results supported the notion that mature adipocytes can directly activate hepatic stellate cells, and the establishment of an in vitro model of adipocytes on HSCs provides an insight into screening of drugs for liver diseases, such as nonalcoholic fatty liver disease.

Control of Adipose Cell Browning and Its Therapeutic Potential

Adipose tissue is the largest endocrine organ in humans and has an important influence on many physiological processes throughout life. An increasing number of studies have described the different phenotypic characteristics of fat cells in adults. Perhaps one of the most important properties of fat cells is their ability to adapt to different environmental and nutritional conditions. Hypothalamic neural circuits receive peripheral signals from temperature, physical activity or nutrients and stimulate the metabolism of white fat cells. During this process, changes in lipid inclusion occur, and the number of mitochondria increases, giving these cells functional properties similar to those of brown fat cells. Recently, beige fat cells have been studied for their potential role in the regulation of obesity and insulin resistance. In this context, it is important to understand the embryonic origin of beige adipocytes, the response of adipocyte to environmental changes or modifications within the body and their ability to transdifferentiate to elucidate the roles of these cells for their potential use in therapeutic strategies for obesity and metabolic diseases. In this review, we discuss the origins of the different fat cells and the possible therapeutic properties of beige fat cells.