分类： 生物学 >> 生物医药 提交时间： 2017-05-10
摘要： MicroRNAs (miRNAs) are one class of short, endogenous RNAs which can regulate gene expression at the post-transcriptional level. Previous analysis revealed that mammalian miRNAs tend to cluster on chromosomes. However, the functional consequences of this clustering and conservation property are largely unknown. In this study we present a method to identify signaling pathways targeted by clustered miRNAs. We performed a computational screen for mouse signaling pathways targeted by miRNA clusters. Here, we report that the target genes of 3 miRNA clusters are overrepresented in 15 signaling pathways. We provided experimental evidence that one miRNA cluster, mmu-mir-183–96–182 targets Irs1, Rasa1, and Grb2, all of which are located in the insulin signaling pathway. Theses results suggest that by targeting components with different roles along a signaling pathway, different members of one miRNA cluster can act as a whole to coordinately control the signal transduction process.
分类： 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间： 2016-05-15
Gao, Mingjing
Zhao, Zhen
Lv, Pengyu
Gao, Juntao
Zhang, Michael
Gao, Mingjing
Zhao, Zhen
Lv, Pengyu
Gao, Juntao
Zhang, Michael
Li, YuFang
Zhao, Baolu
Zhang, Michael
Gao, Mingjing
摘要： Insulin resistance and abdominal obesity are present in the majority of people with the metabolic syndrome. Antioxidant therapy might be a useful strategy for type 2 diabetes and other insulin-resistant states. The combination of vitamin C (Vc) and vitamin E has synthetic scavenging effect on free radicals and inhibition effect on lipid peroxidation. However, there are few studies about how to define the best combination of more than three anti-oxidants as it is difficult or impossible to test the anti-oxidant effect of the combination of every concentration of each ingredient experimentally. Here we present a math model, which is based on the classical Hill equation to determine the best combination, called Fixed Dose Combination (FDC), of several natural anti-oxidants, including Vc, green tea polyphenols (GTP) and grape seed extract proanthocyanidin (GSEP). Then we investigated the effects of FDC on oxidative stress, blood glucose and serum lipid levels in cultured 3T3-L1 adipocytes, high fat diet (HFD)-fed rats which serve as obesity model, and KK-ay mice as diabetic model. The level of serum malondialdehyde (MDA) in the treated rats was studied and Hematoxylin-Eosin (HE) staining or Oil red slices of liver and adipose tissue in the rats were examined as well. FDC shows excellent antioxidant and anti-glycation activity by attenuating lipid peroxidation. FDC determined in this investigation can become a potential solution to reduce obesity, to improve insulin sensitivity and be beneficial for the treatment of fat and diabetic patients. It is the first time to use the math model to determine the best ratio of three anti-oxidants, which can save much more time and chemical materials than traditional experimental method. This quantitative method represents a potentially new and useful strategy to screen all possible combinations of many natural anti-oxidants, therefore may help develop novel therapeutics with the potential to ameliorate the worldwide metabolic abnormalities. (C) 2015 The Authors. Published by Elsevier B.V.
分类： 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间： 2016-05-12
摘要： UBXD8 is a membrane protein that mediates endoplasmic reticulum-associated protein ubiquitination and degradation by interacting with p97NCP. Recently, lipid droplet proteomic studies show the lipid droplet localization of UBXD8. Besides, UBXD8 is also involved in triglyceride metabolism. However, the molecular mechanism by which UBXD8 regulates triglyceride metabolism is still obscure. Here we knocked out UBXD8 in mouse C2C12 myoblasts by CRISPR/Cas9. We selected 2 UBXD8 knockout (KO) clone cell lines from 26 possible KO clones. UBXD8 KO did not change the lipid droplet proteins expression pattern. However, UBXD8 KO led to the accumulation of neutral lipid. Furthermore, our data show that UBXD8 KO could alleviate palmitate-induced insulin resistance and rescue palmitate-induced apoptosis which was characterized by PARP splicing. In addition, the phenotype of palmitate-induced insulin resistance and apoptosis was reappeared after overexpressing UBXD8 in UBXD8 KO cells. These data suggested that UBXD8 plays an important role in lipid metabolism and its abnormity related insulin signal and apoptosis.
分类： 生物学 >> 生物物理学 >> 细胞生物学 提交时间： 2016-05-12
Wei, Yan
Han, Chanshuai
Wang, Yujing
Wu, Beibei
Su, Tao
Liu, Ying
He, Rongqiao
Wang, Yujing
Wu, Beibei
Liu, Ying
He, Rongqiao
摘要： Type 2 diabetes mellitus (T2DM) is regarded as one of the serious risk factors for age-related cognitive impairment; however, a causal link between these two diseases has so far not been established. It was recently discovered that, apart from high D-glucose levels, T2DM patients also display abnormally high concentrations of uric D-ribose. Here, we show for the first time that the administration of D-ribose, the most active glycator among monosaccharides, produces high levels of advanced glycation end products (AGEs) and, importantly, triggers hyperphosphorylation of Tau in the brain of C57BL/6 mouse and neuroblastoma N2a cells. However, the administration of D-glucose showed no significant changes in Tau phosphorylation under the same experimental conditions. Crucially, suppression of AGE formation using an AGEs inhibitor (aminoguanidine) effectively prevents hyperphosphorylation of Tau protein. Further study shows AGEs resulted from ribosylation activate calcium-/calmodulin-dependent protein kinase type II (CaMKII), a key kinase responsible for Tau hyperphosphorylation. These data suggest that there is indeed a mechanistic link between ribosylation and Tau hyperphosphorylation. Targeting ribosylation by inhibiting AGE formation may be a promising therapeutic strategy to prevent Alzheimer's disease-like Tau hyperphosphorylation and diabetic encephalopathies.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-12
摘要： Total internal reflection fluorescence microscope has often been used to study the molecular mechanisms underlying vesicle exocytosis. However, the spatial occurrence of the fusion events within a single cell is not frequently explored due to the lack of sensitive and accurate computer-assisted programs to analyze large image data sets. Here, we have developed an image analysis platform for the nonbiased identification of different types of vesicle fusion events with high accuracy in different cell types. By performing spatiotemporal analysis of stimulus-evoked exocytosis in insulin-secreting INS-1 cells, we statistically prove that individual vesicle fusion events are clustered at hotspots. This spatial pattern disappears upon the disruption of either the actin or the microtubule network; this disruption also severely inhibits evoked exocytosis. By demonstrating that newcomer vesicles are delivered from the cell interior to the surface membrane for exocytosis, we highlight a previously unappreciated mechanism in which the cytoskeleton-dependent transportation of secretory vesicles organizes exocytosis hotspots in endocrine cells.
分类： 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间： 2016-05-12
摘要： The insulin-mimetic and anti-diabetic properties of vanadium and related compounds have been well documented both in vitro and in vivo. However, the molecular basis of the link between vanadium and the insulin signaling pathway in diabetes mellitus is not fully described. We investigated the effects of reactive oxygen species (ROS) induced by oxidovanadium(IV) sulfate (VOSO4) on glucose uptake and the insulin signaling pathway in human hepatoma cell line HepG2. Exposure of cells to VOSO4 (5-50 mu M) resulted in an increase in glucose uptake, insulin receptor (IR) and protein kinase B (Akt) phosphorylation and intracellular ROS generation. Using Western blot, we found that catalase and sodium formate, but not superoxide dismutase, prevented the increase of hydroxyl radical (center dot OH) generation and significantly decreased VOSO4-induced IR and Akt phosphorylation. These results suggest that VOSO4-induced center dot OH radical, which is a signaling species, promotes glucose uptake via the IR/Akt signaling pathway. (C) 2015 Elsevier Inc. All rights reserved.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-12
Xia, Pengyan
Wang, Shuo
Xiong, Zhen
Ye, Buqing
Fan, Zusen
Xiong, Zhen
Fan, Zusen
Huang, Li-Yu
Han, Ze-Guang
Huang, Li-Yu
Han, Ze-Guang
Huang, Li-Yu
Han, Ze-Guang
摘要： RNA virus infection is recognized by the RIG-I family of receptors that activate the mitochondrial adaptor MAVS, leading to the clearance of viruses. Antiviral signalling activation requires strict modulation to avoid damage to the host from exacerbated inflammation. Insulin receptor tyrosine kinase substrate (IRTKS) participates in actin bundling and insulin signalling and its deficiency causes insulin resistance. However, whether IRTKS is involved in the regulation of innate immunity remains elusive. Here we show that IRTKS deficiency causes enhanced innate immune responses against RNA viruses. IRTKS-mediated suppression of antiviral responses depends on the RIG-I-MAVS signalling pathway. IRTKS recruits the E2 ligase Ubc9 to sumoylate PCBP2 in the nucleus, which causes its cytoplasmic translocation during viral infection. The sumoylated PCBP2 associates with MAVS to initiate its degradation, leading to downregulation of antiviral responses. Thus, IRTKS functions as a negative modulator of excessive inflammation.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-12
Du, Yipeng
Zhou, Bo
He, Xiaolong
Wei, Peng
Liu, Pingsheng
Wei, Taotao
Cai, Tanxi
Xue, Peng
Yang, Fuquan
Cai, Tanxi
Xue, Peng
Yang, Fuquan
Li, Tingting
Cai, Tanxi
Zhou, Bo
He, Xiaolong
Wei, Peng
摘要： Protein lysine malonylation, a newly identified protein post-translational modification (PTM), has been proved to be evolutionarily conserved and is present in both eukaryotic and prokaryotic cells. However, its potential roles associated with human diseases remain largely unknown. In the present study, we observed an elevated lysine malonylation in a screening of seven lysine acylations in liver tissues of db/db mice, which is a typical model of type 2 diabetes. We also detected an elevated lysine malonylation in ob/ob mice, which is another model of type 2 diabetes. We then performed affinity enrichment coupled with proteomic analysis on liver tissues of both wild-type (wt) and db/db mice and identified a total of 573 malonylated lysine sites from 268 proteins. There were more malonylated lysine sites and proteins in db/db than in wt mice. Five proteins with elevated malonylation were verified by immunoprecipitation coupled with Western blot analysis. Bioinformatic analysis of the proteomic results revealed the enrichment of malonylated proteins in metabolic pathways, especially those involved in glucose and fatty acid metabolism. In addition, the biological role of lysine malonylation was validated in an enzyme of the glycolysis pathway. Together, our findings support a potential role of protein lysine malonylation in type 2 diabetes with possible implications for its therapy in the future.
分类： 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间： 2016-05-12
Yin, Ruiying
Fang, Li
Li, Yingjia
Wang, Nanping
Yin, Ruiying
Fang, Li
Li, Yingjia
Wang, Nanping
Xue, Peng
Li, Yazi
Chen, Chang
Guan, Youfei
Wang, Nanping
Chang, Yongsheng
Chang, Yongsheng
摘要： Peroxisome proliferator-activated receptor-gamma (PPAR gamma) is a ligand-activated nuclear receptor and plays an essential role in insulin signaling. Macrophage infiltration into adipose tissue is a character of metabolic inflammation and closely related to insulin resistance in type 2 diabetes. The mechanism by which pro-inflammatory macrophages cause insulin resistance remains to be elucidated. Here we showed that coculture with macrophages significantly suppressed the transcriptional activity of PPAR gamma on its target genes in 3T3-L1 preadipocytes and diabetic primary adipocytes, depending on inducible nitric oxide synthase (iNOS). We further showed that PPAR gamma underwent S-nitrosylation in response to nitrosative stress. Mass-spectrometry and site-directed mutagenesis revealed that S-nitrosylation at cysteine 168 was responsible for the impairment of PPAR gamma function. Extended exposure to NO instigated the proteasome-dependent degradation of PPAR gamma. Consistently, in vivo evidence revealed an association of the decreased PPAR gamma protein level with increased macrophage infiltration in visceral adipose tissue (VAT) of obese diabetic db/db mice. Together, our results demonstrated that pro-inflammatory macrophages suppressed PPAR gamma activity in adipocytes via S-nitrosylation, suggesting a novel mechanism linking metabolic inflammation with insulin resistance. (C) 2015 Elsevier Inc. All rights reserved.
分类： 生物学 >> 生物物理学 >> 肿瘤学 提交时间： 2016-05-11
Wu, Beibei
Wei, Yan
Wang, Yujing
Su, Tao
Liu, Ying
He, Rongqiao
He, Rongqiao
He, Rongqiao
Wu, Beibei
Wang, Yujing
Zhou, Lei
摘要： In addition to D-Glucose, D-Ribose is also abnormally elevated in the urine of type 2 diabetic patients, establishing a positive correlation between the concentration of uric D-Ribose and the severity of diabetes. Intraperitoneal injection of D-Ribose causes memory loss and brain inflammation in mice. To simulate a chronic progression of age-related cognitive impairment, we orally administered D-Ribose by gavage at both a low and high dose to 8 week-old male C57BL/6J mice daily for a total of 6 months, followed by behavioral, histological and biochemical analysis. We found that long-term oral administration of D-Ribose impairs spatial learning and memory, accompanied by anxiety-like behavior. Tau was hyperphosphorylated at AT8, S396, S214 and T181 in the brain. A beta-like deposition was also found in the hippocampus for the high dose group. D-Glucose-gavaged mice did not show significant memory loss and anxiety-like behavior under the same experimental conditions. These results demonstrate that a long-term oral administration of D-Ribose not only induces memory loss with anxiety-like behavior, but also elevates A beta-like deposition and Tau hyperphosphorylation, presenting D-Ribose-gavaged mouse as a model for agerelated cognitive impairment and diabetic encephalopathy.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-11
Chen, Jizheng
Guo, Min
Tang, Hong
Chen, Xinwen
Wang, Ning
Dong, Mei
Li, Zhong
Han, Xiao
Wang, Qian
Zhao, Yang
Zhuo, Zhiyong
Zhang, Chao
Chi, Xiumei
Pan, Yu
Jiang, Jing
Niu, Junqi
Yang, Dongliang
摘要： Class Ila histone deacetylases (HDACs), such as HDAC4, HDAC5, and HDAC7, provide critical mechanisms for regulating glucose homeostasis. Here we report that HDAC9, another class Ila HDAC, regulates hepatic gluconeogenesis via deacetylation of a Forkhead box 0 (FoxO) family transcription factor, FoxO1, together with HDAC3. Specifically, HDAC9 expression can be strongly induced upon hepatitis C virus (HCV) infection. HCV-induced HDAC9 upregulation enhances gluconeogenesis by promoting the expression of gluconeogenic genes, including phosphoenolpyruvate carboxykinase and glucose-6-phosphatase, indicating a major role for HDAC9 in the development of HCV-associated exaggerated gluconeogenic responses. Moreover, HDAC9 expression levels and gluconeogenic activities were elevated in livers from HCV-infected patients and persistent HCV-infected mice, emphasizing the clinical relevance of these results. Our results suggest HDAC9 is involved in glucose metabolism, HCV-induced abnormal glucose homeostasis, and type 2 diabetes.
分类： 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间： 2016-05-11
摘要： Background: Phosphatidylinositides in the plasma membrane (PM) are pivotal for cellular functions. Results: Superresolution imaging reveals homogeneous distribution of PI(4,5)P-2, PI4P, and PI(3,4,5)P-3 in the major area of the PM. Conclusion: Phosphatidylinositides detected by PH domains are uniformly distributed in the major regions of the PM, with limited concentration gradients. Significance: This result may imply a new working model of phosphatidylinositides at nanometer scale. Both phosphatidylinositol 4-phosphate (PI4P) and phosphatidylinositol 4,5-bisphosphate (PI(4,5)P-2) are independent plasma membrane (PM) determinant lipids that are essential for multiple cellular functions. However, their nanoscale spatial organization in the PM remains elusive. Using single-molecule superresolution microscopy and new photoactivatable fluorescence probes on the basis of pleckstrin homology domains that specifically recognize phosphatidylinositides in insulin-secreting INS-1 cells, we report that the PI(4,5)P-2 probes exhibited a remarkably uniform distribution in the major regions of the PM, with some sparse PI(4,5)P-2-enriched membrane patches/domains of diverse sizes (383 +/- 14 nm on average). Quantitative analysis revealed a modest concentration gradient that was much less steep than previously thought, and no densely packed PI(4,5)P-2 nanodomains were observed. Live-cell superresolution imaging further demonstrated the dynamic structural changes of those domains in the flat PM and membrane protrusions. PI4P and phosphatidylinositol (3,4,5)-trisphosphate (PI(3,4,5)P-3) showed similar spatial distributions as PI(4,5)P-2. These data reveal the nanoscale landscape of key inositol phospholipids in the native PM and imply a framework for local cellular signaling and lipid-protein interactions at a nanometer scale.
点击量
待评议
点击量
下载量
评论
