circBIRC6 contributes to the development of non-small cell lung cancer via regulating microRNA-217/amyloid beta precursor protein binding protein 2 axis / 中华医学杂志(英文版)

BACKGROUND@#Circular RNAs (circRNAs) are considered to be important regulators in cancer biology. In this study, we focused on the effect of circRNA baculoviral inhibitor of apoptosis protein (IAP) repeat containing 6 (circBIRC6) on non-small cell lung cancer (NSCLC) progression.@*METHODS@#The NSCLC and adjacent non-tumor tissues were collected at Shanghai Ninth People's Hospital. Quantitative real-time polymerase chain reaction was conducted for assessing the levels of circBIRC6, amyloid beta precursor protein binding protein 2 (APPBP2) messenger RNA (mRNA), baculoviral IAP repeat containing 6 mRNA (BIRC6), and microRNA-217 (miR-217). Western blot assay was adopted for measuring the protein levels of APPBP2, E-cadherin, N-cadherin, and vimentin. Colony formation assay, transwell assay, and flow cytometry analysis were utilized for evaluating cell colony formation, metastasis, and apoptosis. Dualluciferase reporter assay and RNA immunoprecipitation assay were carried out to determine the interaction between miR-217 and circBIRC6 and APPBP2 in NSCLC tissues. The murine xenograft model assay was used to investigate the function of circBIRC6 in tumor formation in vivo. Differences were analyzed via Student's t test or one-way analysis of variance. Pearson's correlation coefficient analysis was used to analyze linear correlation.@*RESULTS@#CircBIRC6 was overexpressed in NSCLC tissues and cells. Knockdown of circBIRC6 repressed the colony formation and metastasis and facilitated apoptosis of NSCLC cells in vitro and restrained tumorigenesis in vivo. Mechanically, circBIRC6 functioned as miR-217 sponge to promote APPBP2 expression in NSCLC cells. MiR-217 inhibition rescued circBIRC6 knockdown-mediated effects on NSCLC cell colony formation, metastasis, and apoptosis. Overexpression of miR-217 inhibited the malignant phenotypes of NSCLC cells, while the effects were abrogated by elevating APPBP2.@*CONCLUSIONS@#CircBIRC6 aggravated NSCLC cell progression by elevating APPBP2 via sponging miR-217, which might provide a fresh perspective on NSCLC therapy.

A novel prognostic model for angioimmunoblastic T-cell lymphoma: A retrospective study of 55 cases.

OBJECTIVE: To explore prognostic factors and develop an accurate prognostic prediction model for angioimmunoblastic T-cell lymphoma (AITL). METHODS: Clinical data from Chinese patients with newly diagnosed AITL were retrospectively analysed. Overall survival (OS) and progression-free survival (PFS) were estimated using Kaplan-Meier method survival curves; prognostic factors were determined using a Cox proportional hazards model. The sensitivity and specificity of the predicted survival rates were compared using area under the curve (AUC) of receiver operating characteristic (ROC) curves. RESULTS: The estimated 5-year OS and PFS of 55 eligible patients with AITL were 22% and 3%, respectively. Multivariate analysis showed that the presence of pneumonia, and serous cavity effusions at initial diagnosis were significant prognostic factors for OS. Based on AUC ROC values, our novel prognostic model was superior to IPI and PIT based models and suggested better diagnostic accuracy. CONCLUSIONS: Our prognostic model based on pneumonia, and serous cavity effusions at initial diagnosis enabled a balanced classification of AITL patients into different risk groups.

Caspase-3 over-expression is associated with poor overall survival and clinicopathological parameters in breast cancer: a meta-analysis of 3091 cases.

Caspase-3 is a vital executioner molecule during the apoptotic process. Numerous studies have revealed the close association of caspase-3 expression and breast cancer. Nevertheless, the prognostic value of caspase-3 expression for patients with breast cancer remains uncertain. To thoroughly analyze the prognostic effect of caspase-3 expression on the clinicopathological features and survival of breast cancer, we conducted this meta-analysis. With various search strategies, electronic databases were comprehensively searched. A total of 3091 patients from 21 studies were ultimately obtained. The analysis results indicated that increased expression of caspase-3 had a negative influence on the overall survival (OS) of breast cancer (HR = 1.73, 95%CI 1.12-2.67, P = 0.014). Subgroup analyses based on race revealed that the value of caspase-3 for evaluating patients' OS was more useful in Asian patients (HR = 3.16, 95%CI 1.20-8.15, P = 0.020), and subgroup analyses based on study analytical methods revealed that caspase-3 was a risk factor for breast cancer patients in multivariate overall survival analyses (HR = 1.67, 95%CI 1.02-2.75, P = 0.044). As for the relationship between caspase-3 expression and breast cancer subtype as well as progression, caspase-3 might serve as a risk factor for the progestogen receptor (PR) and human epidermal growth factor receptor-2 (HER-2) subtypes (OR = 1.44, 95%CI 1.09-1.89, P = 0.010; OR = 1.76, 95%CI 1.18-2.62, P = 0.050, respectively) of breast cancer. However, no evidence showed that increased expression of caspase-3 was statistically correlated with tumor differentiation state (low/moderate or high), tumor TNM stage (I-II/III-IV) or lymph node metastasis (-/+). In conclusion, this meta-analysis revealed that increased caspase-3 expression was significantly associated with worse prognosis and two subtypes of breast cancer. More prospective studies are urgently needed to define the prognostic value of caspase-3 expression in patients with breast cancer.

High expression of long non­coding HOTAIR correlated with hepatocarcinogenesis and metastasis.

HOX transcript antisense RNA (HOTAIR), a newly discovered long noncoding RNA (lncRNA), has been reported to be a poor prognostic marker in many types of cancers. The current study attempted to investigate the biological roles and clinicopathlogical implications of HOTAIR in hepatocellular carcinoma (HCC), as well as understand the molecular mechanisms of HOTAIR in HCC progression. HOTAIR expression in 95 HCC patients with paired HCC tissues and adjacent non­cancer tissues were investigated using quantitative reverse transcription­polymerase chain reaction. The association between HOTAIR expression and clinicopathological features was assessed. The effects of HOTAIR were examined in vitro assays by silencing the lncRNA. Pathway analyses were performed to illustrate the biological functions of the HOTAIR and coexpression genes. The expression level of HOTAIR was observed significantly higher in the HCC tissue than the adjacent non­tumor tissue. HOTAIR expression levels were significantly higher in tumor samples from patients with distant metastasis, advanced stage, portal vein tumor embolus, vasoinvasion, tumor capsular infiltration or positive nm23 expression than those from patients without these conditions, correspondingly. The silencing of HOTAIR in liver cancer cells induced the inhibition of cell proliferation and promotion of apoptosis. Several pathways such as extracellular matrix­receptor interaction, focal adhesion, pathways in cancer were annotated with the HOTAIR and coexpression genes. In summary, the present analysis indicates that HOTAIR might be an oncogene in HCC. It functions though promoting tumor cell growth and inhibiting apoptosis. HOTAIR may potentially be involved in HCC metastatic progression by several pathways correlated to cell adhesion, and may be a therapeutic target in future.

Comparative study on biomechanical properties of 3 kinds of rib internal fixators / 医用生物力学

Objective To study and compare biomechanical properties of a newly developed magnesium AZ31B alloy intramedullary nail (AZ31B) with that of imported Poly-L-lactic acid intramedullary nail (PLLA) and pure titanium rib plate (TPRP), so as to provide scientific evidences for better internal fixation in clinical operation. Methods Forty fresh adult ribs were used and divided into 4 groups randomly. Three groups were made lateral rib fracture in midaxillary line and fixed by AZ31B, PLLA and TPRP, respectively, while the group with normal ribs was used as control. Biomechanical properties of specimens in each group were measured and tested using experimental stress analysis. Results (1) Three-point bending strength of internal fixation with AZ31B was close to that of control group (P>0.05), but significantly different to that of TPRP group and PTRP group (P0.05), and the torsional strength of both AZ31B and PTRP was superior to that of PLLA (P<0.05). Conclusions The internal fixation with AZ31B is an ideal mode for treating rib fracture since AZ31B has larger flexural strength than PLLA and TPRP, and its torsional strength was close to PTRP and normal ribs. This study provides some support for future research on biomechanical properties of AZ31B.

Effects of miR-19b overexpression on proliferation, differentiation, apoptosis and Wnt/ß-catenin signaling pathway in P19 cell model of cardiac differentiation in vitro.

MicroRNA (miR)-19b is part of the miR-17-92 cluster associated with cardiac development. Here, we investigated the effects of overexpressing miR-19b on proliferation, differentiation, apoptosis, and regulation of the Wnt/ß-catenin signaling pathway in the multipotent murine P19 cell line that can be induced to undergo cardiogenesis. P19 cells were transfected with the miR-19b plasmid or empty vector, and miR-19b overexpression was verified by Quantitative Real-Time PCR (qPCR). The miR-19b or vector control stable cell lines were selected using Blasticidin S HCl, and their proliferation, cell cycle, and apoptosis levels were analyzed using the Cell Counting Kit-8 and flow cytometry. P19 cell differentiation markers, apoptosis-related genes (bax, bcl-2), and Wnt/ß-catenin signaling pathway-related genes were detected by qPCR, the corresponding proteins by Western blot. Expression of the Wnt pathway and differentiation marker proteins was also verified by immunofluorescence. Morphological changes associated with apoptosis were observed by electron microscopy and Hoechst staining. On the basis of these results, we demonstrated that miR-19b overexpression promoted proliferation and differentiation but inhibited apoptosis in P19 cells; Wnt and ß-catenin expressions were decreased, while that of GSK3ß was increased with miR-19b overexpression. Overexpression of miR-19b inhibited activation of the Wnt/ß-catenin signaling pathway in P19 cells, which may regulate cardiomyocyte differentiation. Our findings may bring new insights into the mechanisms underlying cardiac diseases and suggest that miR-19b is a potential new therapeutic target for cardiovascular diseases.

Association between CYP2C8 (rs1934951) polymorphism and bisphosphonate-related osteonecrosis of the jaws in patients on bisphosphonate therapy: a meta-analysis.

AIMS: Bisphosphonate-related osteonecrosis of the jaws (BONJ) is a severe complication in patients on bisphosphonate therapy. The study was conducted to verify the association between CYP2C8 (rs1934951) polymorphism and BONJ predisposition. METHODS: The relative epidemiologic studies were identified in PubMed and Embase to conduct a meta-analysis using STATA. RESULTS: In the pooled analysis with multiple cancer types, patients carrying the CYP2C8 rs1934951 AA or AG genotype showed no significantly increased BONJ susceptibility compared with those carrying the wild GG genotype [dominant: odds ratio (OR) = 2.05, 95% confidence interval (CI) = 0.67-6.29, p = 0.209; recessive: OR = 1.88, 95% CI = 0.23-15.6, p = 0.560; AG vs. GG: OR = 2.07, 95% CI = 0.80-5.32, p = 0.133, and AA vs. GG: OR = 1.34, 95% CI = 0.48-3.74, p = 0.578]. A significant association between AA and AG genotypes of CYP2C8 (rs1934951) and BONJ risk was found in the subgroup analysis of multiple myeloma (dominant: OR = 5.77, 95% CI = 1.21-27.63, p = 0.028; AG vs. GG: OR = 5.02, 95% CI = 2.06-12.23, p = 0.001, and AA vs. GG: OR = 16.23, 95% CI = 1.72-78.7, p = 0.015). CONCLUSION: The results indicated that AA and AG genotypes of CYP2C8 (rs1934951) might be predictors for multiple myeloma patients at high risk to develop BONJ.

Biomechanical properties of a magnesium alloy absorbable rib intramedullary nail / 中国组织工程研究

BACKGROUND: At present, the materials that are successful y applied in rib fracture internal fixation mainly include titanium, nitinol rib encircling bone bonding plate, imported poly-L-lactic acid absorbable rib nails and anatomical plate. OBJECTIVE: To study the biomechanical characteristics of new magnesium al oy absorbable rib intramedul ary nail in the rib fracture fixation, and to compare with imported poly-L-lactic acid absorbable rib intramedul ary nail in order to provide scientific basis for clinical application. METHODS: Thirty fresh adult fifth rib specimens were col ected, and the specimens were used to make models for the middle rib fractures. The specimens were fixed with AZ31B magnesium al oy absorbable rib intramedul ary nail (magnesium al oy group) and poly-L-lactic acid absorbable rib intramedul ary nail (poly-L-lactic acid group), and the normal rib specimen group was set as control. The biomechanical characteristics of the nails in each group were tested with stress analysis. RESULTS AND CONCLUSION: Three-point bending strength measurement results showed that the bending strength in the magnesium alloy group was close to the normal value of the specimen (P > 0.05), and there was significant difference in the bending strength between magnesium alloy group and the poly-L-lactic acid group (P < 0.05). Torsional strength measurement showed that there was no significant difference in torsional strength between magnesium alloy group and the normal specimens, and the results showed that the magnesium alloy was better than poly-L-lactic acid in fixation (P < 0.05). Tensile tests showed that the tensile strength and anti-pulling force of the magnesium alloy fixation were better than those of poly-L-lactic acid fixation (P < 0.05). The results indicate that the magnesium alloy absorbable rib intramedullary nail is better than poly-L-lactic acid absorbable rib intramedullary nail in strength and tensile strength, which is the ideal fixation material for rib fixation.

Comparative proteomic profiles indicating genetic factors may involve in hepatocellular carcinoma familial aggregation.

Familial aggregation of hepatocellular carcinoma (HCC), the third leading cause of cancer death worldwide, has shown to be a common phenomenon. We investigated the association between the genetic background and HCC familial aggregation. Serum samples were collected from HCC family members and normal control family members for screening the differentially expressed protein peaks with the approach of surface-enhanced laser desorption ionization time-of-flight mass spectrometry. Potential genetically associated protein peaks were selected and further identified by matrix assisted laser desorption ionization-time of flight mass spectrometry. A panel of six protein peaks (m/z 6432.94, 8478.35, 9381.91, 17284.67, 17418.34, and 18111.04) were speculated to reflect the genetic susceptibility of HCC familial aggregation. Three of them (m/z 6432.94, 8478.35, and 9381.91) were selected to identify as the candidate proteins. Nine identified proteins, including mostly apolipoprotein family (ApoA1, ApoA2, ApoC3, ApoE) and serum amyloid A protein (SAA), were found overexpressed in the multiple HCC cases family members. The comparative proteomic profiles have suggested that genetic factors ought to be taken into account for familial aggregation of HCC.

Differential DNA methylation status between human preadipocytes and mature adipocytes.

Obesity is a multifactorial disease resulting from interactions between susceptibility genes, psychosocial, and environmental factors. However, it is becoming evident that interindividual differences in obesity susceptibility depend also on epigenetic factors, although the mechanisms have not been fully elucidated. We have undertaken a genome-wide analysis of DNA methylation of human preadipocytes and mature adipocytes to examine the differences in methylation between them. We found hypomethylation occurring in 2,701 genes and hypermethylation in 1,070 genes after differentiation. Meanwhile, Gene Ontology analysis and Ingenuity Pathway Analysis showed many significant gene functions and pathways with altered methylation status after adipocyte differentiation. In addition, Signal-Net analysis showed that tumor necrosis factor-α, mitogen-activated protein kinase, and interleukin-8 were important to the formation of this network. Our results suggest that DNA methylation mechanisms may be involved in regulating the differentiation process of human preadipocytes.

Effects of embryonic exposure to polychlorinated biphenyls on zebrafish (Danio rerio) retinal development.

Polychlorinated biphenyls (PCBs) are persistent environmental pollutants that affect embryonic development. The purpose of this study was to examine the effects of embryonic exposure to PCBs on early retinal development in zebrafish, Danio rerio. Zebrafish embryos were immediately exposed to different concentrations (0, 0.125, 0.25, 0.5, 1.0 and 2.0 mg) of PCBs per liter of medium at 28.5 °C. Embryos were assessed at 30, 48, 72 and 96 h post-fertilization (hpf) for changes in embryonic survival rate, development, larval retinal morphology and ultrastructure of the retina. The results show that PCB exposure decreased the survival rate of embryos in a time- and dose-dependent manner. Embryos exposed to the higher concentrations of PCBs (0.5, 1.0 and 2.0 mg l(-1) ) displayed obvious gross morphological deformities. At 72 hpf, the retinal layer development of zebrafish was delayed at higher PCB concentrations (1.0 mg l(-1) ). At 96 hpf, irregularity of photoreceptor cells arrangement and thickening of photoreceptor and ganglionic layers were observed in PCB-treated larvae at concentrations of 0.25-1 mg l(-1) . Ultrastructural examination showed signs of growth inhibition of the photoreceptor outer segment at 0.25-1 mg l(-1) PCB exposure at 72 hpf, as well as the appearance of massive vacuoles and holes inside the outer segments in the PCB exposure group at 96 hpf. These results suggest that embryonic exposure to moderate and high levels of PCBs induced developmental deficits in zebrafish retinas, particularly in photoreceptor cells.

Set up drug lymphocyte stimulation test (3H-TdR) and observe its application in drug-induced liver injury / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To set up the drug lymphocyte stimulation test (DLST), as a diagnosis means for DILI which was immunity idiosyncrasy, improve the Diagnosis, level of DILI.</p><p><b>METHOD</b>For the 59 patients who diagnosed as DILI, we separated their PBMC, exploring to the suspicious drug which caused DILI, then use the methods 3H-TdR to test, according to the mixed degree to clear the PBMC count which specific activated by drug.We also set up drug group, negative control and Positive control at the same time. Preliminary experiments was including the best dose of PHA and the best concentration of the drug. We set up 40 healthy group in our experiments as a control, and explore them on the same drug every time. We test the two groups at the same time. We handled the results use t-test.</p><p><b>RESULTS</b>The methods 3H-TdR could be exactly reflect the PBMC's proliferation degree nearly the same when they were be stimulation by PHA or the sensitive drug. When the DILI patients were explore to the suspicious drug, their stimulation index (SI) Obviously higher than 1.8. Form this test, there were 28 in 59 patients of DILI's group were positive (47.46%), SI was from 1.9 to 43.08, the average was 22.49, the healthy group SI was lower than 1.8, the SI of DILI's group was significantly higher than healthy group (5.78+/-0.75/1.16+/-0.25, P less than 0.05). Our test suggested DLST has Higher specificity (94.92%) and sensitivity (47.46%).</p><p><b>CONCLUSION</b>DLST was significance for the patients who diagnosed as immunity idiosyncrasy's DILI, it's reflected these patients' Proliferation of PBMC when explored to the suspicious drug for the second time.</p>

Monoclonal antibody to six transmembrane epithelial antigen of prostate-4 influences insulin sensitivity by attenuating phosphorylation of P13K (P85) and Akt: possible mitochondrial mechanism.

We examined the effects of anti-six-transmembrane epithelial antigen of the prostate-4 (STEAP4) antibodies on glucose transport in mature adipocytes and determined the mechanism of insulin resistance in obesity. Western blotting was performed to determine STEAP4 expression, to assess translocation of insulin-sensitive glucose transporter 4 (GLUT4), and to measure phosphorylation and total protein content of insulin-signaling proteins. Confocal laser microscopy and flow cytometry were used to detect intracellular reactive oxygen species (ROS) and fluctuations in mitochondrial membrane potential (ΔΨ). ATP production was measured by using a luciferase-based luminescence assay kit. After the application of anti-STEAP4 antibodies at 0.002 mg/mL, adipocytes exhibited reduced insulin-stimulated glucose transport by attenuating the phosphorylation of IRS-1, PI3K (p85), and Akt. The antibodies also potentially increase the level of ROS and decrease cellular ATP production and ΔΨ. In conclusion, (i) STEAP4 regulates the function of IRS-1, PI3K, and Akt and decreases insulin-induced GLUT4 translocation and glucose uptake; (ii) ROS-related mitochondrial dysfunction may be related to a reduced IRS-1 correlation with the PI3K signaling pathway, leading to insulin resistance. These observations highlight the potential role of STEAP4 in glucose homeostasis and possibly in the pathophysiology of type 2 diabetes related to obesity and may provide new insights into the mechanisms of insulin resistance in obesity.

UCP4 overexpression improves fatty acid oxidation and insulin sensitivity in L6 myocytes.

Obesity, which is caused by energy uptake being greater than energy expenditure, is widely prevalent today. Currently, only a limited number of efficient interventional strategies are available for the prevention of obesity. Previous studies have shown that UCP4 transcription occurs at a considerable level in mouse skeletal muscle; however, the exact functions of UCP4 remain unclear. In this study, we investigated the effect of UCP4 on mitochondrial function and insulin sensitivity in mature L6 myocytes. UCP4 overexpression in L6 myocytes induced increased mitochondrial carnitine palmitoyltransferase 1A (CPT1A) and decreased citrate synthase (CS) mRNA in the basal condition (i.e., in the absence of insulin). UCP4 overexpression significantly improved insulin sensitivity, increased tyrosine phosphorylation of IRS-1 in the presence of insulin, and significantly reduced intracellular triglyceride (TG). Additionally, intracellular ATP content and mitochondrial membrane potential were downregulated. We also observed that intracellular ROS, mitochondrial morphology, and mitochondrial mtDNA copy number were maintained upon UCP4 expression, with no change in mitochondrial fusion and fission. In summary, our findings provide evidence to show that UCP4 overexpression reduced the insulin sensitivity and mitochondrial fatty acid oxidation of L6 myocytes. These findings support the notion that UCPs are ideal targets for treatment of insulin resistance.

Knockdown of STEAP4 inhibits insulin-stimulated glucose transport and GLUT4 translocation via attenuated phosphorylation of Akt, independent of the effects of EEA1.

The aim of this study was to investigate whether the early endosome antigen 1 (EEA1) and/or PI3K pathway is involved in the molecular mechanisms underlying the effects of the six-transmembrane protein of prostate 4 (STEAP4; also called STAMP2 and TIARP) on the insulin sensitivity of human adipocytes. Our data demonstrated that siRNA-mediated STEAP4 deficiency significantly decreased insulin-stimulated glucose transport in mature human adipocytes by decreasing GLUT4 translocation to the plasma membrane through attenuated Akt phosphorylation. We further found that EEA1 may not be involved in the mechanisms underlying the effects of STEAP4 on insulin-stimulated glucose uptake and GLUT4 translocation, as indicated by the results that i) STEAP4 does not alter the effects of EEA1 on insulin-stimulated glucose uptake and GLUT4 translocation; ii) STEAP4 does not modify the expression of EEA1 protein; and iii) STEAP4 does not interact with EEA1 according to FRET analysis. In conclusion, this study revealed that the knockdown of STEAP4 inhibits insulin-stimulated glucose transport and GLUT4 translocation via the attenuated phosphorylation of Akt, independent of the effects of EEA1.

Left ventricular longitudinal rotation changes in patients with dilated cardiomyopathy detected by two-dimensional speckle tracking imaging / 中华心血管病杂志

<p><b>OBJECTIVE</b>To assess the left ventricular longitudinal rotation (LR) in patients with dilated cardiomyopathy (DCM).</p><p><b>METHODS</b>Conventional echocardiography (GE-Vivid7) was performed in 35 healthy subjects and 42 DCM patients. Left atrial diameter was measured by M-mode echocardiography, left ventricular end-systolic, end-diastolic volume and left ventricular ejection fraction (LVEF) were calculated by bi-plane simpson's method. The peak velocity during early diastole (Ve) and late diastole (Va) of anterior mitral valve were measured by pulse-waved doppler, and the ratio Ve/Va was calculated. The peak radial systolic strain, strain rate in systolic, early and late diastolic periods were measured. Segmental LR and global LR were assessed using two-dimensional speckle tracking imaging (2D-STI).</p><p><b>RESULTS</b>The peak radial systolic strain, strain rate in systolic, early and late diastolic periods in DCM group were significantly lower than in healthy subjects, the rotation degrees of the middle and base lateral, the apex and the base septum walls were significantly lower than those of the healthy subjects. A prominent counterclockwise LR (0.76° ± 2.63°) was shown in healthy subjects while prominent clockwise LR (-1.58° ± 3.42°) was present in DCM patients. The time delay between the left ventricular lateral wall and the base septum wall in DCM patients significantly correlated with the peak LR of the left ventricular (r = 0.409, P < 0.01; r = 0.396, P < 0.01).</p><p><b>CONCLUSIONS</b>2D-STI can be used to assess the LR in DCM patients and a clockwise LR is present in DCM patients which might be caused by the time delay between the left ventricular lateral wall and the base-septum wall.</p>

Monoclonal antibody to the six-transmembrane epithelial antigen of prostate 4 promotes apoptosis and inhibits proliferation and glucose uptake in human adipocytes.

We previously identified the six-transmembrane epithelial antigen of prostate (STEAP) 4 as a novel plasma membrane protein that is up-regulated in obese patients and may play a significant role in the development of human obesity. In this study, a STEAP4-specific antibody was used to characterize the biological functions of the STEAP4 protein in human adipocytes. Cell viability assays (Trypan Blue exclusion), CCK-8 assays and cell cycle analysis showed that the STEAP4 antibody inhibited pre-adipocyte proliferation. Morphological observations by electron microscopy and confocal laser microscopy, annexin V-FITC labeling, caspase-3 and caspase-8 activity assays as well as data from quantitative real-time RT-PCR (qPCR) further determined that the STEAP4 antibody could promote apoptosis in pre-adipocytes. Based on quantitative Oil Red O staining and the expression profiles of specific markers, we demonstrated that the STEAP4 antibody did not affect adipogenesis, but the 2-deoxy-d-[3H]-glucose uptake tests showed that it induced the insulin-stimulated glucose uptake in mature human adipocytes. In conclusion, our results demonstrated that the STEAP4 antibody does not influence human adipocyte differentiation, but it is likely that the STEAP4 protein regulates proliferation and apoptosis and plays an important role in modulating the insulin sensitivity of human adipocytes.

Overexpression of LYRM1 induces mitochondrial impairment in 3T3-L1 adipocytes.

Homo sapiens LYR motif containing 1 (LYRM1) is a recently discovered gene involved in adipose tissue homeostasis and obesity-associated insulin resistance. The exact mechanism by which LYRM1 induces insulin resistance has not yet been fully elucidated. In this study, we demonstrated that the overexpression of LYRM1 in 3T3-L1 adipocytes resulted in reduced insulin-stimulated glucose uptake, an abnormal mitochondrial morphology, and a decrease in intracellular ATP synthesis and mitochondrial membrane potential. In addition, LYRM1 overexpression led to excessive production of intracellular of reactive oxygen species. Collectively, our results indicated that the overexpression of LYRM1 caused mitochondrial dysfunction in adipocytes, which might be responsible for the development of LYRM1-induced insulin resistance.

TNF-alpha induces mitochondrial dysfunction in 3T3-L1 adipocytes.

TNF-alpha was the first proinflammatory cytokine identified linking obesity, insulin resistance and chronic inflammation. However, the mechanism of TNF-alpha in the etiology of insulin resistance is still far from clear. Because the mitochondria play an important role in energy metabolism, we investigated whether mitochondrial dysfunction is involved in pathogenesis of TNF-alpha-mediated insulin resistance. First, a fully differentiated insulin-resistant 3T3-L1 adipocyte model was established by incubating with 4 ng/ml TNF-alpha for 4 d, and then the mitochondrial morphology and functions were observed. TNF-alpha treatment induced pronounced morphological changes in the mitochondria, which became smaller and condensed, and some appeared hollow and absent of cristae. Mitochondrial dynamics changes were observed as increased mitofusion protein mfn1 and mitofission protein Drp1 levels compared with controls. No obvious effects on mitochondrial biogenesis were found. PGC-1alpha levels decreased, but no significant changes were found in mtTFA mRNA expression, NRF1mRNA expression and mitochondrial DNA (mtDNA). TNFalpha treatment also led to decreased mitochondrial membrane potential and reduced production of intracellular ATP, as well as accumulation of significant amounts of reactive oxygen species (ROS). Further research is required to determine if mitochondrial dysfunction is involved in the inflammatory mechanism of insulin resistance and may be a potential target for the treatment of insulin resistance.

Short report: Tissue-specific expression profiles of the uncoupling protein family in normal control mice and genetically ob/ob mice.

Uncoupling proteins (UCPs) located in the inner mitochondrial membrane are involved in the regulation of energy balance. Thus far, 5 UCP isoforms have been identified, but controversies exist in the research focused on the function of the UCPs (except UCP1) in the pathogenesis of obesity. Because of the known cross-reactivity of the antibodies presently available for the detection of UCP proteins, this study systematically analyzed the differential tissue expression profiles of the 5 UCP isoforms in lean control mice and ob/ob mice by using real-time polymerase chain reaction (PCR) analysis. The results show that the tissue-specific expression patterns of individual isoforms in normal and ob/ob mice are considerably different; this will provide new insights into the functions of UCPs in the pathogenesis of genetic obesity.