ABSTRACT
Stem cell activity and cell differentiation is robustly influenced by the nutrient availability in the gonads. The signal that connects nutrient availability to gonadal stem cell activity remains largely unknown. In this study, we show that tumor necrosis factor Eiger (Egr) is upregulated in testicular smooth muscles as a response to prolonged protein starvation in Drosophila testis. While Egr is not essential for starvation-induced changes in germline and somatic stem cell numbers, Egr and its receptor Grindelwald influence the recovery dynamics of somatic cyst stem cells (CySCs) upon protein refeeding. Moreover, Egr is also involved in the refeeding-induced, ectopic expression of the CySC self-renewal protein and the accumulation of early germ cells. Egr primarily acts through the Jun N-terminal kinase (JNK) signaling in Drosophila. We show that inhibition of JNK signaling in cyst cells suppresses the refeeding-induced abnormality in both somatic and germ cells. In conclusion, our study reveals both beneficial and detrimental effects of Egr upregulation in the recovery of stem cells and spermatogenesis from prolonged protein starvation.
Subject(s)
Dietary Proteins/metabolism , Drosophila Proteins/genetics , Drosophila melanogaster/genetics , JNK Mitogen-Activated Protein Kinases/genetics , Membrane Proteins/genetics , Spermatozoa/metabolism , Stem Cells/metabolism , Animals , Cell Differentiation , Dietary Proteins/administration & dosage , Drosophila Proteins/agonists , Drosophila Proteins/metabolism , Drosophila melanogaster/cytology , Drosophila melanogaster/growth & development , Drosophila melanogaster/metabolism , Eating/physiology , Gene Expression Regulation, Developmental , Homeostasis/genetics , JNK Mitogen-Activated Protein Kinases/metabolism , MAP Kinase Signaling System , Male , Membrane Proteins/agonists , Membrane Proteins/metabolism , Spermatogenesis/drug effects , Spermatogenesis/genetics , Spermatozoa/cytology , Spermatozoa/drug effects , Starvation/genetics , Starvation/metabolism , Stem Cell Niche/genetics , Stem Cells/cytology , Stem Cells/drug effects , Testis/cytology , Testis/drug effects , Testis/growth & development , Testis/metabolismABSTRACT
BACKGROUND: Obesity is a chronic metabolic disorder associated with an increase in adipogenesis and often accompanied with fatty liver disease. OBJECTIVE: In this study, we investigated the anti-obesity effects of Hibiscus sabdariffa water extract (HSE) in vivo. METHOD: Eight-weeks-old male mice were divided into six groups (n=8 per group) and were fed either normal feed, a high fat diet (HFD), HFD supplemented with different concentrations of HSE, or HFD supplemented with anthocyanin. After 10 weeks of feeding, all the blood and livers were collected for further analysis. RESULTS: Mesocricetus auratus hamster fed with a high-fat diet developed symptoms of obesity, as determined from their body weight change and from their plasma lipid levels. Meanwhile, HSE treatment reduced fat accumulation in the livers of hamsters fed with HFD in a concentration-dependent manner. Administration of HSE reduced the levels of liver cholesterol and triglycerides, which were elevated by HFD. Analysis of the effect of HSE on paraoxonase 1, an antioxidant liver enzyme, revealed that HSE potentially regulates lipid peroxides and protects organs from oxidation-associated damage. The markers of liver damage such as serum alanine aminotransferase and aspartate aminotransferase levels that were elevated by HFD were also reduced on HSE treatment. The effects of HSE were as effective as treatment with anthocyanin; therefore the anthocyanins present in the HSE may play a crucial role in the protection established against HFD-induced obesity. CONCLUSIONS: In conclusion HSE administration constitutes an effective and viable treatment strategy against the development and consequences of obesity.