ABSTRACT
The treatment of obese patients is a topic investigated by an increasing number of researchers. This study aimed to elucidate the possible inhibitory effect of tangeritin on the development and function of fat cells. 3T3-L1 fat cells were grown to confluence and subjected to different concentrations of tangeritin. The most effective tangeritin inhibition concentration was determined by the MTT assay. The treated cells were subjected to real-time reverse transcriptase PCR and western blot analysis, to detect changes in the CCAAT/enhancer binding protein (C/EBP)α, C/EBPß, and peroxisome proliferator activated receptor (PPAR)γ expression levels. The MTT assay revealed that the fat cell growth was inhibited at a 20 ng/mL concentration of tangeritin. The results of real-time PCR revealed a significant decrease in the expression of C/EBPα, C/EBPß, and PPARγ mRNA, following the treatment with tangeritin. Western blot analysis also presented similar results at a protein level. Therefore, we concluded that tangeritin inhibits adipogenesis via the down-regulation of C/EBPα, C/EBPß, and PPARγ mRNA and protein expression in 3T3-L1 cells.
Subject(s)
Adipogenesis/drug effects , Adipogenesis/genetics , CCAAT-Enhancer-Binding Protein-alpha/genetics , CCAAT-Enhancer-Binding Protein-beta/genetics , Flavones/pharmacology , Gene Expression Regulation/drug effects , PPAR gamma/genetics , 3T3-L1 Cells , Adipocytes/drug effects , Adipocytes/metabolism , Animals , Cell Proliferation/drug effects , Mice , RNA, Messenger/geneticsABSTRACT
To explore the role of metalloproteinase-1 (TIMP-1) tissue inhibitor in the mechanisms of kidney aging, we observed the effects of sense and antisense transfection of TIMP-1 and of metalloproteinase (MMP) inhibitors on phosphatase and tensin homolog (PTEN), vascular endothelial growth factor (VEGF), and Flk-1 expression in TIMP-1 transgenic human proximal tubular epithelial cells (HKCs). Transfected HKCs were co-incubated with 100 µM MMP-2 and MMP-9 inhibitor III for 24 h to affect enzyme inhibition. TIMP-1, MMP-2, MMP-9, PTEN, VEGF, and Flk-1 mRNA expression was detected by reverse transcription-polymerase chain reaction. PTEN, VEGF, and Flk-1 protein expression in cells of each experimental group was measured by indirect immunofluorescence. We found that PTEN expression was up-regulated (P < 0.05) in the sense TIMP-1-transfected group (P < 0.05) compared with the non-transfected and empty vector groups, and that expression of VEGF and Flk-1 was down-regulated (P < 0.05). In contrast, the antisense TIMP-1 transgenic group showed the opposite results (P < 0.05). No significant differences in expression of PTEN, VEGF, or Flk-1 were observed among the MMP- 2/MMP-9 inhibitor III, non-transfected, and empty vector groups (P > 0.05). These results suggest that in the progression of renal aging, high expression of TIMP-1 up-regulates PTEN expression through an MMP-independent pathway, and subsequently down-regulates the expression of VEGF and Flk-1, indicating that PTEN and TIMP-1 are involved in the aging-associated impairment of renal angiogenesis. Our study provides a theoretical basis for further exploration of the mechanism underlying TIMP- 1 participation in renal aging progression.
Subject(s)
Aging/genetics , Kidney Tubules, Proximal/metabolism , Neovascularization, Pathologic/genetics , PTEN Phosphohydrolase/biosynthesis , Aging/metabolism , Aging/pathology , Gene Expression Regulation , Humans , Kidney Tubules, Proximal/pathology , Matrix Metalloproteinase 2/biosynthesis , Matrix Metalloproteinase 2/genetics , Matrix Metalloproteinase 9/biosynthesis , Matrix Metalloproteinase 9/genetics , Neovascularization, Pathologic/pathology , PTEN Phosphohydrolase/genetics , RNA, Messenger/biosynthesis , Tissue Inhibitor of Metalloproteinase-1/biosynthesis , Tissue Inhibitor of Metalloproteinase-1/genetics , Transfection , Vascular Endothelial Growth Factor A/biosynthesis , Vascular Endothelial Growth Factor A/genetics , Vascular Endothelial Growth Factor Receptor-2/biosynthesis , Vascular Endothelial Growth Factor Receptor-2/geneticsABSTRACT
High-altitude pulmonary edema (HAPE) is a life-threatening condition caused by acute exposure to high altitude. Accumulating evidence suggests that genetic factors play an important role in the etiology of HAPE. However, conclusions from association studies have been hindered by limited sample size due to the rareness of this disease. It is known that mitochondria are critical for hypoxic adaptation, and mitochondrial malfunction can be an important factor in HAPE development. Therefore, we tested the hypothesis that mitochondrial DNA haplotypes and polymorphisms affect HAPE susceptibility. We recruited 204 HAPE patients and 174 healthy controls in Tibet (3658 m above sea level), all Han Chinese, constituting the largest sample size of all HAPE vulnerability studies. Among mtDNA haplogroups, we found that haplogroup D4 is associated with resistance to HAPE, while haplogroup B is a genetic risk factor for this condition. Haplogroup D4 (tagged by 3010A) may enhance the stability of 16S rRNA, resulting in reduced oxidative stress and protection against HAPE. Within haplogroup B, subhaplogroup B4c (tagged by 15436A and 1119C) was associated with increased risk for HAPE, while subhaplogroup B4b may protect against HAPE. We indicate that there are differences in HAPE susceptibility among mtDNA haplogroups. We conclude that mitochondria are involved in adverse reactions to acute hypoxic exposure; our finding of differences in susceptibility as a function of mitochondrial DNA haplotype may shed light on the pathogenesis of other disorders associated with hypoxia, such as chronic obstructive pulmonary disease.