Showing papers by "Lei Wei published in 2013"

Distinct roles for ROCK1 and ROCK2 in the regulation of cell detachment

Abstract: This study, using mouse embryonic fibroblast (MEF) cells derived from ROCK1−/− and ROCK2−/− mice, is designed to dissect roles for ROCK1 and ROCK2 in regulating actin cytoskeleton reorganization induced by doxorubicin, a chemotherapeutic drug. ROCK1−/− MEFs exhibited improved actin cytoskeleton stability characterized by attenuated periphery actomyosin ring formation and preserved central stress fibers, associated with decreased myosin light chain 2 (MLC2) phosphorylation but preserved cofilin phosphorylation. These effects resulted in a significant reduction in cell shrinkage, detachment, and predetachment apoptosis. In contrast, ROCK2−/− MEFs showed increased periphery membrane folding and impaired cell adhesion, associated with reduced phosphorylation of both MLC2 and cofilin. Treatment with inhibitor of myosin (blebbistatin), inhibitor of actin polymerization (cytochalasin D), and ROCK pan-inhibitor (Y27632) confirmed the contributions of actomyosin contraction and stress fiber instability to stress-induced actin cytoskeleton reorganization. These results support a novel concept that ROCK1 is involved in destabilizing actin cytoskeleton through regulating MLC2 phosphorylation and peripheral actomyosin contraction, whereas ROCK2 is required for stabilizing actin cytoskeleton through regulating cofilin phosphorylation. Consequently, ROCK1 and ROCK2 can be functional different in regulating stress-induced stress fiber disassembly and cell detachment.

The Age-Related Changes in Cartilage and Osteoarthritis

Abstract: Osteoarthritis (OA) is closely associated with aging, but its underlying mechanism is unclear. Recent publications were reviewed to elucidate the connection between aging and OA. With increasing OA incidence, more senior people are facing heavy financial and social burdens. Age-related OA pathogenesis is not well understood. Recently, it has been realized that age-related changes in other tissues besides articular cartilage may also contribute to OA development. Many factors including senescence-related secretory phenotypes, chondrocytes' low reactivity to growth factors, mitochondrial dysfunction and oxidative stress, and abnormal accumulation of advanced glycation end products (AGEs) may all play key roles in the pathogenesis of age-related OA. Lately, epigenetic regulation of gene expression was recognized for its impact on age-related OA pathogenesis. Up to now, few studies have been reported about the role of miRNA and long-noncoding RNA (lncRNA) in age-related OA. Research focusing on this area may provide valuable insights into OA pathogenesis. OA-induced financial and social burdens have become an increasingly severe threat to older population. Age-related changes in noncartilage tissue should be incorporated in the understanding of OA development. Growing attention on oxidative stress and epigenetics will provide more important clues for the better understanding of the age-related OA.

Rho kinases in cardiovascular physiology and pathophysiology: the effect of fasudil.

Abstract: Rho kinase (ROCK) is a major downstream effector of the small GTPase RhoA. ROCK family, consisting of ROCK1 and ROCK2, plays central roles in the organization of actin cytoskeleton and is involved in a wide range of fundamental cellular functions, such as contraction, adhesion, migration, proliferation, and apoptosis. Due to the discovery of effective inhibitors, such as fasudil and Y27632, the biological roles of ROCK have been extensively explored with particular attention on the cardiovascular system. In many preclinical models of cardiovascular diseases, including vasospasm, arteriosclerosis, hypertension, pulmonary hypertension, stroke, ischemia-reperfusion injury, and heart failure, ROCK inhibitors have shown a remarkable efficacy in reducing vascular smooth muscle cell hypercontraction, endothelial dysfunction, inflammatory cell recruitment, vascular remodeling, and cardiac remodeling. Moreover, fasudil has been used in the clinical trials of several cardiovascular diseases. The continuing utilization of available pharmacological inhibitors and the development of more potent or isoform-selective inhibitors in ROCK signaling research and in treating human diseases are escalating. In this review, we discuss the recent molecular, cellular, animal, and clinical studies with a focus on the current understanding of ROCK signaling in cardiovascular physiology and diseases. We particularly note that emerging evidence suggests that selective targeting ROCK isoform based on the disease pathophysiology may represent a novel therapeutic approach for the disease treatment including cardiovascular diseases.

Celastrol prevents atherosclerosis via inhibiting LOX-1 and oxidative stress.

Abstract: Celastrol is a triterpenoid compound extracted from the Chinese herb Tripterygium wilfordii Hook F. Previous research has revealed its anti-oxidant, anti-inflammatory, anti-cancer and immunosuppressive properties. Here, we investigated whether celastrol inhibits oxidized low-density lipoprotein (oxLDL) induced oxidative stress in RAW 264.7 cells. In addition, the effect of celastrol on atherosclerosis in vivo was assessed in apolipoprotein E knockout (apoE−/−) mouse fed a high-fat/high-cholesterol diet (HFC). We found that celastrol significantly attenuated oxLDL-induced excessive expression of lectin-like oxidized low density lipoprotein receptor-1(LOX-1) and generation of reactive oxygen species (ROS) in cultured RAW264.7 macrophages. Celastrol also decreased IκB phosphorylation and degradation and reduced production of inducible nitric oxide synthase (iNOS), nitric oxide (NO) and proinflammatory cytokines such as tumor necrosis factor (TNF)-α and IL-6. Celastrol reduced atherosclerotic plaque size in apoE−/− mice. The expression of LOX-1 within the atherosclerotic lesions and generation of superoxide in mouse aorta were also significantly reduced by celastrol while the lipid profile was not improved. In conclusion, our results show that celastrol inhibits atherosclerotic plaque developing in apoE−/− mice via inhibiting LOX-1 and oxidative stress.

Activation of Wnt/β-catenin Pathway by Exogenous Wnt1 Protects SH-SY5Y Cells Against 6-Hydroxydopamine Toxicity

Abstract: Wnt1, initially described as a modulator of embryonic development, has recently been discovered to exert cytoprotective effects in cellular models of several diseases, including Parkinson's disease (PD). We, therefore, examined the neuroprotective effects of exogenous Wnt1 on dopaminergic SH-SY5Y cells treated with 6-hydroxydopamine (6-OHDA). Here, we show that 10–500 μM 6-OHDA treatment decreased cell viability and increased lactate dehydrogenase (LDH) leakage. SH-SY5Y cells treated with 100 μM 6-OHDA for 24 h showed reduced Wnt/β-catenin activity, decreased mitochondrial transmembrane potential, elevated levels of reactive oxidative species (ROS) and phosphatidylserine (PS) extraversion, increased levels of Chop and Bip/GRP78 and reduced level of p-Akt (Ser473). In contrast, exogenous Wnt1 attenuated 6-OHDA-induced changes. These results suggest that activation of the Wnt/β-catenin pathway by exogenous Wnt1 protects against 6-OHDA-induced changes by restoring mitochondria and endoplasmic reticulum (ER) function.

CXCR4-targeted therapy inhibits VEGF expression and chondrosarcoma angiogenesis and metastasis

Abstract: Chondrosarcoma is notable for its lack of response to conventional cytotoxic chemotherapy, propensity for developing lung metastases, and poor survival. Therefore, a better understanding of angiogenic and metastatic pathways is needed. Multiple pathways regulate angiogenesis and metastasis, including chemokines and their receptors. In this study, we investigated chemokine (C-X-C motif) receptor 4 (CXCR4) signaling in chondrosarcoma and tested the hypotheses that CXCR4 inhibition suppresses tumor angiogenesis and metastasis. CXCR4 expression, analyzed by real-time PCR and Western blot, was increased in human chondrosarcoma cell line JJ compared with normal chondrocytes and was further increased in JJ by hypoxia (2% O2), vascular endothelial growth factor A (VEGFA; 10 ng/mL), and in xenograft tumors in nude mice. The CXCR4 ligand CXCL12 (10 ng/mL) doubled secreted VEGFA, measured with ELISA, under hypoxic conditions and this conditioned media increased human umbilical vein endothelial cell tube formation. These effects were inhibited by CXCR4 siRNA or AMD3100 (5 μg/mL). In a xenograft mouse model, four weeks of AMD3100 treatment (1.25 mg/kg, intraperitoneally twice daily) inhibited tumor angiogenesis, tumor growth, and metastasis. VEGFA content in tumor extracts was decreased (7.19 ± 0.52 ng/mL control vs. 3.96 ± 0.66 treatment) and bioimaging of angiogenesis was decreased by 56%. Tumor volumes averaged 4.44 ± 0.68 cm(3) in control compared with 2.48 ± 0.61 cm(3) in the treatment group. The number of lung metastatic nodules was 23 ± 9 in control compared with 10 ± 6 in the treatment group (N = 8/group). Therefore, CXCR4-targeted therapy may be a treatment strategy for chondrosarcoma.

Nutrition and degeneration of articular cartilage

Abstract: Purpose To determine the importance of synovial fluid (SF) or subchondral bone marrow (BM) as nutrition sources in cartilage degeneration.

Astragalus Polysaccharide Suppresses Skeletal Muscle Myostatin Expression in Diabetes: Involvement of ROS-ERK and NF-κB Pathways

Abstract: Objective. The antidiabetes drug astragalus polysaccharide (APS) is capable of increasing insulin sensitivity in skeletal muscle and improving whole-body glucose homeostasis. Recent studies suggest that skeletal muscle secreted growth factor myostatin plays an important role in regulating insulin signaling and insulin resistance. We hypothesized that regulation of skeletal muscle myostatin expression may be involved in the improvement of insulin sensitivity by APS. Methods. APS was administered to 13-week-old diabetic KKAy and nondiabetic C57BL/6J mice for 8 weeks. Complementary studies examined APS effects on the saturated acid palmitate-induced insulin resistance and myostatin expression in C2C12 cells. Results. APS treatment ameliorated hyperglycemia, hyperlipidemia, and insulin resistance and decreased the elevation of myostatin expression and malondialdehyde production in skeletal muscle of noninsulin-dependent diabetic KKAy mice. In C2C12 cells in vitro, saturated acid palmitate-induced impaired glucose uptake, overproduction of ROS, activation of extracellular regulated protein kinases (ERK), and NF-κB were partially restored by APS treatment. The protective effects of APS were mimicked by ERK and NF-κB inhibitors, respectively. Conclusion. Our study demonstrates elevated myostatin expression in skeletal muscle of type 2 diabetic KKAy mice and in cultured C2C12 cells exposed to palmitate. APS is capable of improving insulin sensitivity and decreasing myostatin expression in skeletal muscle through downregulating ROS-ERK-NF-κB pathway.

An integrated proteomic and metabolomic study on the chronic effects of mercury in Suaeda salsa under an environmentally relevant salinity.

Abstract: As an environmental contaminant, mercury is of great concern due to its high risk to environmental and human health. The halophyte Suaeda salsa is the dominant plant in the intertidal zones of the Yellow River Delta (YRD) where has been contaminated by mercury in some places. This study aimed at evaluating the chronic effects of mercury (Hg2+, 20 mu g L-1) and the influence of an environmentally relevant salinity (NaCl, 500 mM) on mercury-induced effects in S. salsa. A total of 43 protein spots with significant changes were identified in response to Hg2+, salinity and combined Hg2+ and salinity. These proteins can be categorized into diverse functional classes, related to metabolic processes, photosynthesis, stress response, protein fate, energy metabolism, signaling pathways and immunosuppression. Metabolic responses demonstrated that Hg2+ could disturb protein and energy metabolisms in S. salsa co-exposed with or without salinity. In addition, both antagonistic and synergistic effects between Hg2+ and salinity were confirmed by differential levels of proteins (magnesium-chelatase and ribulose-l,5-bisphosphate carboxylase/oxygenase) and metabolites (valine, malonate, asparagine, glycine, fructose and glucose) in S. salsa. These findings suggest that a combination of proteomics and metabolomics can provide insightful information of environmental contaminant-induced effects in plants at molecular levels.

Dissecting the roles of ROCK isoforms in stress-induced cell detachment

Abstract: The homologous Rho kinases, ROCK1 and ROCK2, are involved in stress fiber assembly and cell adhesion and are assumed to be functionally redundant. Using mouse embryonic fibroblasts (MEFs) derived from ROCK1−/− and ROCK2−/− mice, we have recently reported that they play different roles in regulating doxorubicin-induced stress fiber disassembly and cell detachment: ROCK1 is involved in destabilizing the actin cytoskeleton and cell detachment, whereas ROCK2 is required for stabilizing the actin cytoskeleton and cell adhesion. Here, we present additional insights into the roles of ROCK1 and ROCK2 in regulating stress-induced impairment of cell-matrix and cell-cell adhesion. In response to doxorubicin, ROCK1−/− MEFs showed significant preservation of both focal adhesions and adherens junctions, while ROCK2−/− MEFs exhibited impaired focal adhesions but preserved adherens junctions compared with the wild-type MEFs. Additionally, inhibition of focal adhesion or adherens junction formations by chemical inhibitors abolished the anti-detachment effects of ROCK1 deletion. Finally, ROCK1−/− MEFs, but not ROCK2−/− MEFs, also exhibited preserved central stress fibers and reduced cell detachment in response to serum starvation. These results add new insights into a novel mechanism underlying the anti-detachment effects of ROCK1 deletion mediated by reduced peripheral actomyosin contraction and increased actin stabilization to promote cell-cell and cell-matrix adhesion. Our studies further support the differential roles of ROCK isoforms in regulating stress-induced loss of central stress fibers and focal adhesions as well as cell detachment.

Matrine inhibits the adhesion and migration of BCG823 gastric cancer cells by affecting the structure and function of the vasodilator-stimulated phosphoprotein (VASP)

Abstract: Matrine inhibits the adhesion and migration of BCG823 gastric cancer cells by affecting the structure and function of the vasodilator-stimulated phosphoprotein (VASP)

Gate length related transfer characteristics of GaN-based high electron mobility transistors

Abstract: The measured drain current of GaN high electron mobility transistor (HEMT) shows a saturated characteristic as gate bias increases. HEMTs with short gate length have drain currents saturate more readily as compared to long gate length. In this paper, the relationship between drain currents saturation and gate bias was analyzed by using a simple series resistance model and was also validated by two-dimensional device simulation. The effects of these saturated transfer characteristics on electron mobility extraction of GaN HEMT were evaluated. Furthermore, the possible extension of GaN HEMT to logic inverter by utilizing the feature of saturation was also discussed.

Type II collagen fragment HELIX-II is a marker for early cartilage lesions but does not predict the progression of cartilage destruction in human knee joint synovial fluid.

Abstract: To determine whether there is a direct correlation between the concentration of type II collagen fragment HELIX-II in synovial fluid and the severity of cartilage damage at the knee joint, 83 patients who had undergone knee arthroscopy or total knee replacement were enrolled in this study (49% women, mean ± SD age 49.5 ± 19). The content of HELIX-II in the synovial fluid samples was measured by enzyme-linked immunosorbent assay (ELISA). Cartilage damage at the knee joint was classified during arthroscopy or direct surgical observation, using the Outerbridge cartilage damage scoring system. The maximum damage score was defined as the highest score among the six areas of the knee joint, and the cumulative score was defined as the sum of the scores of the six areas of the knee joint. The intra-assay and inter-assay variations of the HELIX-II ELISA were lower than 13 and 15%, respectively. The level of HELIX-II in the severely damaged cartilage groups (cumulative scores = 11–24 or maximum score = 2–4) was much higher than in the slightly damaged cartilage groups (cumulative scores = 0–10 or maximum score = 0–1). The level of HELIX-II in cartilage from severely damaged cartilage groups was significantly higher than in the slightly damaged groups, but no significant difference was detected in the level of HELIX-II among the severely damaged cartilage sub-groups. There was a significant correlation between the HELIX-II concentration in the synovial fluid and the cumulative (r = 0.807) and maximum scores (r = 0.794). Thus, elevated HELIX-II level is correlated with early cartilage lesions, but does not have the sensitivity to predict the progression of severity of cartilage damage in the knee joint.

Correction: Attenuation of osteoarthritis via blockade of the SDF-1/CXCR4 signaling pathway

Abstract: CorrectionAfter publication of our recent article [1], we noticed that this study was initiated in Qian Chens lab and that we had inadvertently omitted Qian Chen as a co-author. e study was also supported by other grants from NIH. Revised acknowledgment and authors contribution para-graphs appear below. e author list is now complete and the competing interests section modi“ ed accordingly.