VTechWorks staff will be away for the Thanksgiving holiday beginning at noon on Wednesday, November 27, through Friday, November 29. We will resume normal operations on Monday, December 2. Thank you for your patience.

Browsing by Author "Luo, Jing"

Now showing 1 - 10 of 10
  • Thumbnail Image
    Deletion of GPR30 Drives the Activation of Mitochondrial Uncoupling Respiration to Induce Adipose Thermogenesis in Female Mice
    Luo, Jing; Wang, Yao; Gilbert, Elizabeth R.; Liu, Dongmin (Frontiers, 2022-05-03)
    Thermogenic adipocytes possess a promising approach to combat obesity with its capability promoting energy metabolism. We previously discovered that deletion of GPR30 (GPRKO), a presumably membrane-associated estrogen receptor, protected female mice from developing obesity, glucose intolerance, and insulin resistance when challenged with a high-fat diet (HFD). In vivo, the metabolic phenotype of wild type (WT) and GPRKO female mice were measured weekly. Acute cold tolerance test was performed. Ex vivo, mitochondrial respiration of brown adipose tissue (BAT) was analyzed from diet-induced obese female mice of both genotypes. In vitro, stromal vascular fractions (SVF) were isolated for beige adipocyte differentiation to investigate the role of GPR30 in thermogenic adipocyte. Deletion of GPR30 protects female mice from hypothermia and the mitochondria in BAT are highly energetic in GPRKO animals while the WT mitochondria remain in a relatively quiescent stage. Consistently, GPR30 deficiency enhances beige adipocyte differentiation in white adipose tissue (WAT) and activates the thermogenic browning of subcutaneous WAT due to up-regulation of UCP-1, which thereby protects female mice from HFD-induced obesity. GPR30 is a negative regulator of thermogenesis, which at least partially contributes to the reduced adiposity in the GPRKO female mice. Our findings provide insight into the mechanism by which GPR30 regulates fat metabolism and adiposity in female mice exposed to excess calories, which may be instrumental in the development of new therapeutic strategies for obesity.
  • Thumbnail Image
    Dietary Anti-Aging Polyphenols and Potential Mechanisms
    Luo, Jing; Si, Hongwei; Jia, Zhenquan; Liu, Dongmin (MDPI, 2021-02-13)
    For years, the consumption of a diet rich in fruits and vegetables has been considered healthy, increasing longevity, and decreasing morbidities. With the assistance of basic research investigating the potential mechanisms, it has become clear that the beneficial effects of plant-based foods are mainly due to the large amount of bioactive phenolic compounds contained. Indeed, substantial dietary intervention studies in humans have supported that the supplementation of polyphenols have various health-promoting effects, especially in the elderly population. In vitro examinations on the anti-aging mechanisms of polyphenols have been widely performed, using different types of natural and synthetic phenolic compounds. The aim of this review is to critically evaluate the experimental evidence demonstrating the beneficial effects of polyphenols on aging-related diseases. We highlight the potential anti-aging mechanisms of polyphenols, including antioxidant signaling, preventing cellular senescence, targeting microRNA, influencing NO bioavailability, and promoting mitochondrial function. While the trends on utilizing polyphenols in preventing aging-related disorders are getting growing attention, we suggest the exploration of the beneficial effects of the combination of multiple polyphenols or polyphenol-rich foods, as this would be more physiologically relevant to daily life.
  • Thumbnail Image
    Dietary Supplementation of Chinese Ginseng Prevents Obesity and Metabolic Syndrome in High-Fat Diet-Fed Mice
    Li, Xiaoxiao; Luo, Jing; Babu, Pon Velayutham Anandh; Zhang, Wei; Gilbert, Elizabeth R.; Cline, Mark A.; McMillan, Ryan P.; Hulver, Matthew W.; Alkhalidy, Hana; Zhen, Wei; Zhang, Haiyan; Liu, Dongmin (Mary Ann Liebert, 2014-12-01)
    Obesity and diabetes are growing health problems worldwide. In this study, dietary provision of Chinese ginseng (0.5 g/kg diet) prevented body weight gain in high-fat (HF) diet-fed mice. Dietary ginseng supplementation reduced body fat mass gain, improved glucose tolerance and whole body insulin sensitivity, and prevented hypertension in HF diet-induced obese mice. Ginseng consumption led to reduced concentrations of plasma insulin and leptin, but had no effect on plasma adiponectin levels in HF diet-fed mice. Body temperature was higher in mice fed the ginseng-supplemented diet but energy expenditure, respiration rate, and locomotive activity were not significantly altered. Dietary intake of ginseng increased fatty acid oxidation in the liver but not in skeletal muscle. Expression of several transcription factors associated with adipogenesis (C/EBP alpha and PPAR gamma) were decreased in the adipose tissue of HF diet-fed mice, effects that were mitigated in mice that consumed the HF diet supplemented with ginseng. Abundance of fatty acid synthase (FASN) mRNA was greater in the adipose tissue of mice that consumed the ginseng-supplemented HF diet as compared with control or un-supplemented HF diet-fed mice. Ginseng treatment had no effect on the expression of genes involved in the regulation of food intake in the hypothalamus. These data suggest that Chinese ginseng can potently prevent the development of obesity and insulin resistance in HF diet-fed mice.
  • Thumbnail Image
    Does GPER Really Function as a G Protein-Coupled Estrogen Receptor in vivo?
    Luo, Jing; Liu, Dongmin (2020-03-31)
    Estrogen can elicit pleiotropic cellular responses via a diversity of estrogen receptors (ERs)-mediated genomic and rapid non-genomic mechanisms. Unlike the genomic responses, where the classical nuclear ER alpha and ER beta act as transcriptional factors following estrogen binding to regulate gene transcription in estrogen target tissues, the non-genomic cellular responses to estrogen are believed to start at the plasma membrane, leading to rapid activation of second messengers-triggered cytoplasmic signal transduction cascades. The recently acknowledged ER, GPR30 or GPER, was discovered in human breast cancer cells two decades ago and subsequently in many other cells. Since its discovery, it has been claimed that estrogen, ER antagonist fulvestrant, as well as some estrogenic compounds can directly bind to GPER, and therefore initiate the non-genomic cellular responses. Various recently developed genetic tools as well as chemical ligands greatly facilitated research aimed at determining the physiological roles of GPER in different tissues. However, there is still lack of evidence that GPER plays a significant role in mediating endogenous estrogen action in vivo. This review summarizes current knowledge about GPER, including its tissue expression and cellular localization, with emphasis on the research findings elucidating its role in health and disease. Understanding the role of GPER in estrogen signaling will provide opportunities for the development of new therapeutic strategies to strengthen the benefits of estrogen while limiting the potential side effects.
  • Thumbnail Image
    Estradiol signaling mediates gender difference in visceral adiposity via autophagy
    Tao, Zhipeng; Zheng, Louise D.; Smith, Cayleen; Luo, Jing; Robinson, Alex; Almeida, Fabio A.; Wang, Zongwei; Olumi, Aria F.; Liu, Dongmin; Cheng, Zhiyong (Springer Nature, 2018)
    Excessive adiposity (particularly visceral fat mass) increases the risks of developing metabolic syndrome. Women have lower deposit of visceral fat than men, and this pattern becomes diminished postmenopausally, but the underlying mechanism remains largely unknown. Here, we show that the gender difference in visceral fat distribution is controlled by an estradiol–autophagy axis. In C57BL/6J and wild-type control mice, a higher visceral fat mass was detected in the males than in the females, which was associated with lower expression of estrogen receptor α (ERα) and more active autophagy in males vs. females. However, deletion of ERα normalized autophagy activity and abolished the gender difference in visceral adiposity. In line with the adiposity-reducing effect of the ERα–autophagy axis, we found that downregulation of ERα and increased autophagy activity were required for adipogenesis, while induction of estradiol signaling dampened autophagy and drastically prevented adipogenesis. Mechanistically, the estradiol-ERα signaling activated mTOR, which phosphorylated and inhibited ULK1, thereby suppressing autophagy and adipogenesis. Together, our study suggests that the lower visceral adiposity in the females (vs. the males) arises from a more active estradiol-ERα signaling, which tunes down autophagy and adipogenesis.
  • Thumbnail Image
    Exploring the metabolic role of GPR30 in mice
    Luo, Jing (Virginia Tech, 2019-06-21)
    Recent studies showed that GPR30, a seven-transmembrane G protein-coupled receptor, is a novel estrogen receptor (ER) that mediates some biological events elicited by estrogen in several types of cancer cells. However, its physiological or pathological role in vivo is unclear. For the first project of my dissertation, I investigated the physiological role(s) of GPR30 in energy metabolism by using transgenic mouse model as well as immortalized cell lines and primary stromal cells. We discovered for the first time that GPR30 knockout (GPRKO) female mice were protected from high-fat diet (HFD)-induced obesity, glucose intolerance, and insulin resistance. The decreased body weight gain in GPRKO female mice is due to the reduction in body fat mass. These effects occurred in the absence of significant changes in food intake, intestinal fat absorption, or triglyceride metabolism. However, GPR30 had no significant metabolic effects in male mice fed the HFD and both sexes of mice fed a chow diet. Further, GPR30 expression levels in fat tissues of WT obese female mice greatly increased, whereas ERα/β expression was not altered. Deletion of GPR30 reduced adipogenic differentiation of adipose tissue-derived stromal cells. Conversely, activation of GPR30 enhanced adipogenic differentiation of 3T3-L1 preadipocytes. For the second project, I explored whether estrogen acts through GPR30 to affect adiposity in female mice. For this study, I generated and examined three independent transgenic mouse models, aromatase (Ar) knockout (ArKO) mice, GPRKO, and GPR30 and Ar double knockout (DKO) mice. We discovered that GPR30 deficiency had limited effects on energy metabolism in mice fed a standard chow diet (STD). However, deletion of GPR30 promoted metabolic flexibility in both genders fed a HFD regardless of the presence of estrogen, suggesting that GPR30 may not solely act as an ER. Consistent with our previous findings, GPRKO mice had higher body temperature, indicating that GPR30 deficiency may promote thermogenesis and energy metabolism, resulting in the reduced fat depots and enhanced metabolic flexibility. For the third project, I further explored whether GPR30 is involved in regulating browning of adipose tissue and thermogenesis in mice. The results show that the expression of UCP-1, the key regulator of thermogenic browning, was higher in the adipose tissue of HFD-fed GPRKO female mice as compared with that of WT mice. Consistently, deletion of GPR30 enhanced mitochondrial respiration in brown adipose tissue (BAT), suggesting that GPR30 deficiency at least partially suppressed the fat accumulation by promoting thermogenesis and dissipating energy. Ex vivo, the expression of thermogenic genes and UCP-1 protein level were upregulated in beige adipocytes differentiated from GPR30-deficient stromal vascular fraction (SVF) cells. These findings provide evidence for the first time that deletion of GPR30 reduces adiposity, promotes white adipose beigeing and thermogenesis, therefore preventing the development of obesity in female mice exposed to excess energy. Further investigations elucidating the underlying mechanism by which GPR30 promotes obesity in females could provide a novel therapeutic target to fight obesity in females.
  • Thumbnail Image
    The Flavonoid Kaempferol Ameliorates Streptozotocin-Induced Diabetes by Suppressing Hepatic Glucose Production
    Alkhalidy, Hana; Moore, Will; Wang, Yao; Luo, Jing; McMillan, Ryan P.; Zhen, Wei; Zhou, Kequan; Liu, Dongmin (MDPI, 2018-09-13)
    In diabetes mellitus, the excessive rate of glucose production from the liver is considered a primary contributor for the development of hyperglycemia, in particular, fasting hyperglycemia. In this study, we investigated whether kaempferol, a flavonol present in several medicinal herbs and foods, can be used to ameliorate diabetes in an animal model of insulin deficiency and further explored the mechanism underlying the anti-diabetic effect of this flavonol. We demonstrate that oral administration of kaempferol (50 mg/kg/day) to streptozotocin-induced diabetic mice significantly improved hyperglycemia and reduced the incidence of overt diabetes from 100% to 77.8%. This outcome was accompanied by a reduction in hepatic glucose production and an increase in glucose oxidation in the muscle of the diabetic mice, whereas body weight, calorie intake, body composition, and plasma insulin and glucagon levels were not altered. Consistently, treatment with kaempferol restored hexokinase activity in the liver and skeletal muscle of diabetic mice while suppressed hepatic pyruvate carboxylase activity and gluconeogenesis. These results suggest that kaempferol may exert antidiabetic action via promoting glucose metabolism in skeletal muscle and inhibiting gluconeogenesis in the liver.
  • Thumbnail Image
    GPR30 regulates diet-induced adiposity in female mice and adipogenesis in vitro
    Wang, Aihua; Luo, Jing; Moore, William; Alkhalidy, Hana; Wu, Ling; Zhang, Jinhua; Zhen, Wei; Wang, Yao; Clegg, Deborah J.; Xu, Bin; Cheng, Zhiyong; McMillan, Ryan P.; Hulver, Matthew W.; Liu, Dongmin (Nature Publishing Group, 2016-10-04)
  • Thumbnail Image
    Investigating the potential anti-diabetic effect of sulforaphane
    Luo, Jing (Virginia Tech, 2014-07-01)
    Type 2 diabetes (T2D) is a major public health issue worldwide and it currently affects nearly 26 million people in the United States. It is estimated that one third of Americans will have diabetes by 2050. T2D is a result of chronic insulin resistance and loss of beta-cell mass and function. Both in experimental animals and people, obesity is a leading pathogenic factor for developing insulin resistance, which is always associated with the impairment in energy metabolism, causing increased intracellular fat content in skeletal muscle, liver, fat, as well as pancreatic islets. Constant insulin resistance will progress to T2D when beta-cells are unable to secret adequate amount of insulin to compensate for decreased insulin sensitivity. In the present study, I investigated whether sulforaphane, a natural compound derived from cruciferous vegetables, can prevent high-fat (HF) diet-induced obesity and diabetes in C57BL/6 mice. Dietary intake of sulforaphane (250 mg/kg diet) prevented hyperglycemia and increased insulin sensitivity in HF diet-induced obese mice. Mice treated with sulforaphane had significant lower serum insulin levels (1.93±0.11 μg/dl) as compared to those without treatment (3.09±0.27 μg/dl, P<0.05). In second study, administration of sulforaphane (40 mg/kg body weight daily via gavage) in obese mice enhanced body weight loss and improved insulin sensitivity. Moreover, sulforaphane increased pyruvate oxidation by 28.85% (P<0.05) and enhanced fatty acid oxidation efficiency by 2.2 fold (P<0.05) in primary human muscle cells. These results suggest that sulforaphane may be a naturally occurring insulin-sensitizing agent that is capable of preventing T2D.
  • Thumbnail Image
    Sulforaphane Ameliorates High-Fat-Diet-Induced Metabolic Abnormalities in Young and Middle-Aged Obese Male Mice
    Luo, Jing; Alkhalidy, Hana; Jia, Zhenquan; Liu, Dongmin (MDPI, 2024-03-29)
    Type 2 diabetes (T2D) is still a fast-growing health problem globally. It is evident that chronic insulin resistance (IR) and progressive loss of β-cell mass and function are key features of T2D etiology. Obesity is a leading pathogenic factor for developing IR. The aim of the present study was to determine whether sulforaphane (SFN), a natural compound derived from cruciferous vegetables, can prevent (prevention approach) or treat (treatment approach) obesity and IR in mouse models. We show that dietary intake of SFN (0.5 g/kg of HFD) for 20 weeks suppressed high-fat diet (HFD)-induced fat accumulation by 6.04% and improved insulin sensitivity by 23.66% in young male mice. Similarly, dietary provision of SFN (0.25 g/kg) significantly improved blood lipid profile, glucose tolerance, and insulin sensitivity of the middle-aged male mice while it had little effects on body composition as compared with the HFD group. In the treatment study, oral administration of SFN (40 mg/kg) induced weight loss and improved insulin sensitivity and plasma lipid profile in the diet-induced-obesity (DIO) male mice. In all three studies, the metabolic effects of SFN administration were not associated with changes in food intake. In vitro, SFN increased glucose uptake in C2C12 myotubes and increased fatty acid and pyruvate oxidation in primary human skeletal muscle cells. Our results suggest that SFN may be a naturally occurring insulin-sensitizing agent that is capable of improving the metabolic processes in HFD-induced obesity and IR and thereby may be a promising compound for T2D prevention.