ABSTRACT
Chronic kidney disease is the main cause of mortality in patients with tuberous sclerosis complex (TSC) disease. The mechanisms underlying TSC cystic kidney disease remain unclear, with no available interventions to prevent cyst formation. Using targeted deletion of TSC1 in nephron progenitor cells, we showed that cysts in TSC1-null embryonic kidneys originate from injured proximal tubular cells with high mTOR complex 1 activity. Injection of rapamycin to pregnant mice inhibited the mTOR pathway and tubular cell proliferation in kidneys of TSC1-null offspring. Rapamycin also prevented renal cystogenesis and prolonged the life span of TSC newborns. Gene expression analysis of proximal tubule cells identified sets of genes and pathways that were modified secondary to TSC1 deletion and rescued by rapamycin administration during nephrogenesis. Inflammation with mononuclear infiltration was observed in the cystic areas of TSC1-null kidneys. Dexamethasone administration during pregnancy decreased cyst formation by not only inhibiting the inflammatory response, but also interfering with the mTORC1 pathway. These results reveal mechanisms of cystogenesis in TSC disease and suggest interventions before birth to ameliorate cystic disease in offspring.
Subject(s)
Dexamethasone/pharmacology , Kidney Diseases, Cystic/prevention & control , Sirolimus/pharmacology , Tuberous Sclerosis/prevention & control , Animals , Female , Kidney/metabolism , Kidney Diseases, Cystic/drug therapy , Mechanistic Target of Rapamycin Complex 1/drug effects , Mice, Transgenic , Pregnancy , Tuberous Sclerosis/genetics , Tuberous Sclerosis Complex 1 Protein/drug effects , Tuberous Sclerosis Complex 1 Protein/genetics , Tumor Suppressor Proteins/geneticsABSTRACT
INTRODUCTION AND OBJECTIVES: The incidence of non-alcoholic fatty liver disease (NAFLD) is increasing. Previous studies indicated that Liraglutide, glucagon-like peptide-1 analogue, could regulate glucose homeostasis as a valuable treatment for Type 2 Diabetes. However, the precise effect of Liraglutide on NAFLD model in rats and the mechanism remains unknown. In this study, we investigated the molecular mechanism by which Liraglutide ameliorates hepatic steatosis in a high-fat diet (HFD)-induced rat model of NAFLD in vivo and in vitro. MATERIALS AND METHODS: NALFD rat models and hepatocyte steatosis in HepG2 cells were induced by HFD and palmitate fatty acid treatment, respectively. AMPK inhibitor, Compound C was added in HepG2 cells. Autophagy-related proteins LC3, Beclin1 and Atg7, and AMPK pathway-associated proteins were evaluated by Western blot and RT-PCR. RESULTS: Liraglutide enhanced autophagy as showed by the increased expression of the autophagy markers LC3, Beclin1 and Atg7 in HFD rats and HepG2 cells treated with palmitate fatty acid. In vitro, The AMPK inhibitor exhibited an inhibitory effect on Liraglutide-induced autophagy enhancement with the deceased expression of LC3, Beclin1 and Atg7. Additionally, Liraglutide treatment elevated AMPK levels and TSC1, decreased p-mTOR expression. CONCLUSIONS: Liraglutide could upregulate autophagy to decrease lipid over-accumulation via the AMPK/mTOR pathway.
Subject(s)
Autophagy/drug effects , Liraglutide/pharmacology , Liver/drug effects , Non-alcoholic Fatty Liver Disease/metabolism , Adenylate Kinase/drug effects , Adenylate Kinase/metabolism , Animals , Autophagy/genetics , Autophagy-Related Protein 7/drug effects , Autophagy-Related Protein 7/genetics , Autophagy-Related Protein 7/metabolism , Beclin-1/drug effects , Beclin-1/genetics , Beclin-1/metabolism , Diet, High-Fat , Hep G2 Cells , Humans , In Vitro Techniques , Liver/metabolism , Microtubule-Associated Proteins/drug effects , Microtubule-Associated Proteins/genetics , Microtubule-Associated Proteins/metabolism , Palmitates/pharmacology , Rats , TOR Serine-Threonine Kinases/drug effects , TOR Serine-Threonine Kinases/metabolism , Tuberous Sclerosis Complex 1 Protein/drug effects , Tuberous Sclerosis Complex 1 Protein/metabolismABSTRACT
OBJECTIVE: To explore the mechanism of electropuncture (EA) for reducing diet-induced obesity (DIO) rat weight through tuberous sclerosis complex 1 (TSC1 )-mammalian target of rapa- mycin (mTOR) signal pathway in hypothalamus. METHODS: Forty male SD rats were randomly divided into the model group (n =30) and the normal control group (n =10). DIO rat model was prepared by high fat forage for 12 successive weeks. Successfully modeled 19 rats were further randomly divided into the model group (n =9) and the EA group (n =10). EA at Tianshu (ST25) , Sanyinjiao (SP6) , Zhongwan ( RN12) , Zusanli (ST36) was performed in the EA group, 5 successive days per week with a 2-day rest, 4 weeks in total. No intervention was given to rats in the model group and the normal control group. Body weight was observed in all rats. Methylation of TSC1 promotor was detected by bisulfite sequencing method. mRNA expression of mTOR in hypothalamus was detected by RT-PCR. RESULTS: After EA treatment body weight in the EA group were obviously reduced (P <0. 05). Compared with the normal control group, body weight was not statistically different between the model group and the EA group after treatment (P> 0. 05). Methylation rate of TSC1 promotor was higher in model group (94. 0% ±4. 5%) than in the normal control group (87. 0% ±3. 6%) and the EA group (87. 4% ±3. 9%) (P <0. 05). Expression of mTOR in the model group (1. 84 ±0. 51) was higher than that in the normal control group (1. 02 ±0. 22) and the EA group (1. 46 ±0. 29) (P <0. 05). CONCLUSION: EA could lower DIO rats' body weight by down-regulating methylation rate of TSC1 promotor and regulating expression of mTOR in hypothalamus.
