Search

Objectives: To investigate the effects and molecular mechanisms of asiatic acid on β-cell function in type 2 diabetes mellitus (T2DM)., Methods: The T2DM model was established by high fat diet and streptozotocin injection in ICR mice, and the effects of asiatic acid on glucose regulation were investigated in model mice. The islets were isolated from palmitic acid-treated diabetic mice. ELISA was used to detect the glucose-stimulated insulin secretion, tumor necrosis factor (TNF)-α and interleukin (IL)-6. ATP assay was applied to measure ATP production, and Western blotting was used to detect protein expression of mature β cell marker urocortin (Ucn) 3 and mitofusin (Mfn) 2. The regulatory effects of asiatic acid on glucose-stimulated insulin secretion (GSIS) and Ucn3 expression were also investigated after siRNA interference with Mfn2 or treatment with TNF-α., Results: Asiatic acid with the dose of 25 mg·kg －1 ·d －1 had the best glycemic control in T2DM mice and improved the homeostasis model assessment β index. Asiatic acid increased the expression of Mfn2 and Ucn3 protein and improved the GSIS function of diabetic β cells in vitro and in vivo (both P <0.05). Moreover, it improved the ATP production of islets of T2DM mice in vitro ( P <0.05). Interfering Mfn2 with siRNA blocked the up-regulation of Ucn3 and GSIS induced by asiatic acid. Asiatic acid inhibited islet TNF-α content and increased Mfn2 and Ucn3 protein expression inhibited by TNF-α., Conclusions: Asiatic acid improves β cell insulin secretion function in T2DM mice by maintaining the β cell maturity, which may be related to the TNF-α/Mfn2 pathway.

Objective: To investigate the effects of Bax inhibitor 1 (BI- 1) and optic atrophy protein 1 (OPA1) on vascular calcification (VC)., Methods: Mouse models of VC were established in ApoE-deficient (ApoE -/- ) diabetic mice by high-fat diet feeding for 12 weeks followed by intraperitoneal injections with N ε -carboxymethyl-lysine for 16 weeks. ApoE -/- mice (control group), ApoE -/- diabetic mice (VC group), ApoE -/- diabetic mice with BI-1 overexpression (VC + BI-1 TG group), and ApoE -/- diabetic mice with BI-1 overexpression and OPA1 knockout (VC+BI-1 TG +OPA1 -/- group) were obtained for examination of the degree of aortic calcification using von Kossa staining. The changes in calcium content in the aorta were analyzed using ELISA. The expressions of Runt-related transcription factor 2 (RUNX2) and bone morphogenetic protein 2 (BMP-2) were detected using immunohistochemistry, and the expression of cleaved caspase-3 was determined using Western blotting. Cultured mouse aortic smooth muscle cells were treated with 10 mmol/L β-glycerophosphate for 14 days to induce calcification, and the changes in BI-1 and OPA1 protein expressions were examined using Western blotting and cell apoptosis was detected using TUNEL staining., Results: ApoE -/- mice with VC showed significantly decreased expressions of BI-1 and OPA1 proteins in the aorta ( P =0.0044) with obviously increased calcium deposition and expressions of RUNX2, BMP-2 and cleaved caspase-3 ( P = 0.0041). Overexpression of BI-1 significantly promoted OPA1 protein expression and reduced calcium deposition and expressions of RUNX2, BMP-2 and cleaved caspase-3 ( P =0.0006). OPA1 knockdown significantly increased calcium deposition and expressions of RUNX2, BMP-2 and cleaved caspase-3 in the aorta ( P =0.0007)., Conclusion: BI-1 inhibits VC possibly by promoting the expression of OPA1, reducing calcium deposition and inhibiting osteogenic differentiation and apoptosis of the vascular smooth muscle cells.

Objective: To investigate the effect of endoplasmic reticulum (ER)-mitochondria coupling and the expression of mitofusion 2 (Mfn2) in periodontal ligament stem cells (PDLSC), so as to provide a theoretical basis and therapeutic target for promoting periodontal regeneration in treatment of periodontitis. Methods: The periodontal ligament tissue was scraped from extracted intact human teeth and teeth with periodontitis collected in the Department of Oral and Maxillofacial Surgery, the Fourth Military Medical University. The health PDLSC (H-PDLSC) and inflammatory PDLSC (P-PDLSC) were obtained respectively from the primary culture of the human teeth and cloned using 1imited diluted method. The level of ER-mitochondrial coupling was observed by transmission electron microscopy and organelle-specific fluorescence staining. Quantitative real-time PCR (qPCR) was used to detect the expression of Mfn2 in H-PDLSC and P-PDLSC. Tumor necrosis factor alpha (TNF-α) was used to simulate the inflammatory microenvironment. H-PDLSC was cultured in normal medium and media containing 5 and 10 mg/L TNF-α, named as H-PDLSC group, H-PDLSC+TNF-α (5 mg/L) group and H-PDLSC+TNF-α (10 mg/L) group, respectively. At the 7th day, qPCR was applied to detect the mRNA level of Mfn2. The expression of Mfn2 in P-PDLSC was down-regulated by small interfering RNA siMfn2. The osteogenic differentiation of P-PDLSC and P-PDLSC+siMfn2 were examined by qPCR at the 7th day, and alizarin red staining and cetyl pyridine chloride quantitative analysis at the 28th day after osteogenic induction. Results: The level of ER-mitochondrial coupling in the P-PDLSC group (the length of the coupling structure/mitochondrial perimeter was 0.55±0.10, the length of the coupling structure/endoplasmic reticulum perimeter was 0.44±0.08) was significantly higher than that in the H-PDLSC group ( P< 0.01). The co-localization of endoplasmic reticulum and mitochondria of P-PDLSC group was 0.71±0.09, which was significantly higher than that of H-PDLSC group ( P< 0.01). The expression level of Mfn2 in P-PDLSC (1.46±0.10) was higher than that in H-PDLSC (0.99±0.08). The expression levels of Mfn2 in H-PDLSC+TNF-α (5 mg/L) and H-PDLSC+TNF-α (10 mg/L) groups were 1.28±0.19, 1.54±0.43, respectively, which were both significantly higher than that in H-PDLSC (0.82±0.14) ( P< 0.01). P-PDLSC transfected with siMfn2 down-regulated the expression of Mfn2, and the osteogenic differentiation ability of P-PDLSC was restored. The results showed that the expression of alkaline phosphatase, Runt-related transcription factor-2 (RUNX2) and osteocalcin mRNA in P-PDLSC+siMfn2 group were significantly higher than that of the control group ( P< 0.01). The alizarin red staining and quantitative results of cetyl pyridinium chloride were consistent with the qPCR results. Conclusions: In the microenvironment of inflammation, ER-mitochondrial coupling and the expression of Mfn2 of PDLSC increased, which might lead to a decrease in osteogenic differentiation of PDLSC. The specific mechanism needs to be further studied.

Objective: To compare the differences of mitochondrial functions between keloid fibroblasts and normal skin fibroblasts and explore its relationship with cell proliferation., Methods: Keloid fibroblasts (KFb) and normal skin fibroblasts (NFb) were isolated by explants culture method. KFb and NFb were cultured under normoxia or hypoxia (2％ O2).Differences of cell proliferation were detected by CCK-8.Flow cytometer was used to detect the content of mitochondria and reactive oxygen species (ROS) in KFb and NFb. Ultra-structures of mitochondria in KFb and NFb were observed by transmission electron microscope (TEM).Mitochondria fusion/fission related genes MFN1,MFN2 and FIS1 were detected by RT-PCR. Oxygen consumption rate, lactate production and ATP contents were determined by spectrophotometry., Results: KFb showed a higher proliferation rate compared with NFb, especially under hypoxia. The oxygen consumption rate, ATP content, lactate production and ROS of KFb were lower than NFb under normoxia. After incubated under hypoxia, there was a significant increase in oxygen consumption, ATP content, lactate production and ROS in KFb, while NFb showed less increase compared with KFb. KFb had 15.33％ more mitochondrion than NFb, and expressions of MFN1, MFN2, FIS1 in KFb were 33.27％,113.39％ and 20.34％ higher compared with NFb. Under TEM, KFb showed an increase of enlarged mitochondrion, with disrupted inner membrane and loss of cristae., Conclusions: KFb may have dysfunctions of mitochondrion which lead to changes of cell metabolism and continuous proliferation of KFb.

To observe the protective effect and mechanism of Sailuotong capsule in focal cerebral ischemia/reperfusion. The 90 min middle cerebral artery occlusion (MCAO) reperfusion model was established. The expressions of dynamin-related protein 1 ( Drp1) and optic atrophy 1 (Opa1) were tested by Western blot. The transmission electron microscope was used to observe the changes in the mitochondrial ultra-structure. The pathological morphological changes were observed through the HE staining. The immunohistochemical method was used to test Drp1 and Opa1 expressions. Sailuotong capsule (33, 16.5 mg x kg(-1), ig) can inhibit the abnormal mitochondrial fission and fusion in the cortical area on the ischemia side and the mitochondrial fission gene expression and promote the mitochondrial fusion gene Opa1 expression, so as to alleviate the energy metabolism disorder caused by ischemia/reperfusion. Sailuotong capsule can inhibit the abnormal mitochondrial dynamics in peri-ischemic regions and maintain the normal morphology of mitochondria, which may be the mechanism of Sailuotong capsule in promoting the self-recovery function in the ischemic brain region.

Objective: To determine the differential protein and mRNA expressions of mitochondria fusion protein-2 (Mfn2) in hepatic tissues in conditions of cirrhosis and acute on chronic liver failure using rat model systems,and to determine the correlative effects on production of adenosine triphosphate (ATP) and reactive oxygen species (ROS)., Methods: A liver cirrhotic rat model (LC rats) was established by intraperitoneal injection of carbon tetrachloride (CCl4,in vegetable oil),and these mice were subsequently used (10 weeks later) to establish the acute on chronic liver failure rat model (LF rats) by injecting lipopolysaccharide and D-amino-galactose.Control groups (normal controls,NC rats) were established for each model by intraperitoneal injection of vegetable oil only.Protein expression of Mfn2 in liver was quantified by western blotting with fluorescence densitometry and immunofluorescence staining,and mRNA expression was measured by real-time fluorescence quantitative PCR.ROS levels in liver were measured by fluorescence spectrophotometry,and ATP content was measured by bioluminescence assay.Significance of inter-group differences was assessed by one-way ANOVA,and correlations were determined using bivariate statistical modeling., Results: Mfn2 protein expression was significantly lower in the liver tissues from modeled rats than that from the control rats (LC:0.051+/-0.004 and LF:0.037+/-0.007 vs.NC:0.254+/-0.008;F=444.98,P less than 0.05).The mRNA expression followed the same trend of lower expression (LC:21.21+/-0.93 and LF:24.35+/-0.85 vs.NC:19.09+/-0.69; F=66.941,P less than 0.05).The ATP content in liver tissues was also significantly lower in the modeled rats (LC:2.07+/-0.05 mol/L and LF:1.81+/-0.11 mol/L vs.NC:3.24+/-0.08 mol/L; F =574.21,P less than 0.05).Lower Mfn2 expression was correlated with lower ATP content (r =0.982) and higher ROS content (r =0.803)., Conclusion: Reduced Mfn2 expression in liver tissue may cause a decrease in ATP synthesis and increase in ROS generation,thereby disrupting metabolism and increasing oxidative stress in the liver under conditions of cirrhosis and liver failure.

Influenza virus assembly requires the completion of viral protein and vRNP transport to the assembly site at the plasma membrane. Therefore, efficient regulation of intracellular transport of the viral proteins and vRNPs to the surface of the host cell is especially important for virus morphogenesis. Influenza A virus uses the machineries of host cells to transport its own components including ribonucleoproteins (vRNPs) and three transmembrane proteins hemagglutinin (HA), neuraminidase (NA) and matrix 2 protein (M2). It has been shown that newly synthesized vRNPs are associated with active form of Rab11 and accumulate at recycling endosomes adjacent to the microtubule organizing center (MTOC) following nuclear export. Subsequently, they are transported along the microtubule network toward the plasma membranes in cargo vesicles. The viral transmembrane proteins are translated on the rough endoplasmic reticulum and transported to the virus assembly site at the plasma membrane. It has been found that several host factors such as ARHGAP21 and GTPase Cdc42 are involved in regulation of intracellular trafficking of influenza A virus transmembrane proteins including NA. In this review, we will highlight the current knowledge about anterograde transport and its regulation of the influenza A virus transmembrane proteins and genome in the host cytoplasm.

Objective: To investigate the effects of hydrodynamics-mediated RNAi for Mfn2 gene expression in liver and the levels of blood sugar and fat in mice., Methods: Fifty-six male BALB/c mice were randomly divided into normal control group (NC, n = 8), negative control group (HK, n = 24) and transfection group (Mfn2, n = 24) according to random digits table. 1.5 ml plasmid (negative control or Mfn2 shRNA, 75mug for each mouse) diluted into phosphate buffered solution (PBS) was injected into the HK and Mfn2 groups mice via hydrodynamic intravascular injection. Mfn2 mRNA and protein expression in hepatic tissue was detected by RT-PCR and Western-blot 24 hours, 72 hours and 120 hours respectively after injection. At the same time, the levels of fasted blood sugar (FBS) and triglyceride (TG) were measured., Results: Compared with HK mice, the expressions of Mfn2 mRNA (1.00+/-0.03 vs 1.14+/-0.07, t = 4.027, P = 0.007; 1.01+/-0.053 vs 1.18+/-0.07, t = 4.234, P = 0.006) and protein (7.81+/-0.80 vs 8.01+/-0.08, t = 2.941, P = 0.042; 8.05+/-0.15 vs 8.56+/-0.014, t = 4.883, P = 0.039) decreased markedly in Mfn2 mice in 72 and 120 hours after injection. In the fasting state, in 24 hours after injection, FBS in Mfn2 group was significantly lower than that in HK group [(2.65+/-0.70 vs 5.28+/-0.82) mmol/L, t = 6.879, P value less than 0.01] and TG was also significantly higher than that in HK group [(1.96+/-0.32 vs 1.12+/-0.16) mmol/L, t = -6.711, P value less than 0.01]. No statistical differences found between the NC and HK groups for FBS and TG (F = 1.412, P = 0.26; F = 2.711, P = 0.14). The plasma glucose level in Mfn2 mice was significantly higher than that in HK mice [(7.23+/-0.82 vs 5.18+/-0.69) mmol/L, t = 2.050, P value less than 0.01; (7.00+/-0.67 vs 6.05+/-0.76) mmol/L, t = 3.57, P = 0.023] in 72 and 120 hours after injection. However, no differences found between the two groups for blood TG [(1.53+/-0.27 vs 1.37+/-0.18) mmol/L, t = 0.160, P = 0.23; (1.84+/-0.30 vs 1.52+/-0.37) mmol/L, t = 0.330, P = 0.503]., Conclusion: The data indicate that hydrodynamics- mediated RNAi for Mfn2 gene can effectively inhibit the expression of target gene in mice liver in 72 and 120 hours after shRNA administration, and the inhibition of hepatic Mfn2 can induce glycometabolic and fat metabolic disorder.

Mitochondria are dynamic organelles and maintain their structure through two opposing processes of fusion and fission. In mammals, there are many factors which influence the equilibrium between mitochondrial fusion and fission. It has been known that mitochondrial fusion is controlled by mitochondria-shaping proteins, including the large GTPase mitofusins (Mfn1/2) and optic atrophy protein 1 (OPA1), whereas the protein Fis1 and dynamin-related protein 1 (Drp1) are the key mediators of mitochondrial fission. Recent data revealed the relationship between mitochondrial fusion/fission and Ca2+ signaling. Ca2+ handling is controlled by the change of mitochondrial fission-fusion balance. On the other hand, intra- and near-mitochondrial Ca2+ signals can modify mitochondrial morphology and cellular distribution.

Mitofusin 2 (Mfn2) is a mitochondrial dynamin-related protein involved in the mitochondrial fusion reaction and is also connected to an altered mitochondrial energy supply. Mfn2 is a signaling molecule, plays an important role in cell proliferation, differentiation and apoptosis, which participates in the pathophysiology of several cardiovascular diseases, such as hypertension, restenosis after angioplasty, atherosclerosis, cardiac hypertrophy, and cardiac oxidative stress injury. Regulating the mitochondria-related metabolism, Mfn2 affects diabetes and insulin resistance pathogenesis. In addition, Mfn2 could be an important biomarker and therapeutic target molecule for cardiovascular diseases.

Peptide signals play very important roles in the process of plant development, growth and defense to various stresses. Apoplast calmodulin, putative extracellular peptide signal, not only existed in extracellular space, but also had biological functions. So it is important to provide evidences for extracellular calmodulin binding sites and mechanism of signaling. In this paper, exogenous FITC-ACaM2 was observed only in the outside of cell using Laser scanning confocal microscope (Fig. 2), and (35)S-ACaM2 binding to suspension-cultured Arabidopsis cells at 25 degrees C was equal to that at 4 degrees C (Fig. 3), provided direct evidences that exogenous calmodulin was not endocytosed into cytoplasm. SDS-PAGE and radiography showed (35)S-ACaM2 intactly existed in extracellular space of suspension-cultured Arabidopsis cells (Fig. 4). Exogenous ACaM2 could specifically promote activity of GTPase(Fig. 5) and [Ca(2+)](cyt) (Fig. 6). These results indicated exogenous calmodulin could bind to the surface sites of the suspension-cultured Arabidopsis cells, and then the extracellular signal was transferred into cytoplasm signal by transmembrane signaling to regulate the biological functions.

Objective: To investigate the molecular characteristic of interferon-gamma mediating protective immunity against schistosomiasis japonica in mice., Methods: CD4+ T cells were isolated from spleens of mice infected with Schistosoma japonicum at different time-points. The cDNA microarray technique combined with RT-PCR was used to explore IFN-gamma inducible GTPase family gene expression profile of CD4+ T cell. IGTP, a representative IFN-gamma, inducible GTPase having vital anti-infection activity, was amplified from spleen of BALB/c mice using RT-PCR, then cloned into pGEM(r)-T easy vector for sequencing., Results: IFN-gamma inducible GTPase family had the similar characteristic over the course of S. japonicum infection. The gene expression of these members were up-regulated or had little change at 3 wk post-infection, then down-modulated from 6 wk to 13 wk post-infection, which was also confirmed by RT-PCR. As for IGTP, two inserts were identified after sequencing. One was 142 bp shorter than another, but the fragment was lost due to low annealing temperature., Conclusion: There is a dramatic inhibition of IFN-gamma pathway and IFN-gamma-dependent anti-infective immunity during the infection of S. japonicum.

Regulators of G-protein signaling (RGSs) are recently identified negative regulator of G-protein signaling, most of the RGSs act as GTPase activating proteins (GAPs). RGSs can selectively act on Gas and their effects are scrupulously regulated in vivo. It is believed that we can learn more about regulation of signal transduction from the development of research on RGSs.