[Properties of gelatin-polyethylene glycol hydrogel loaded with silver nanoparticle Chlorella and its effects on healing of infected full-thickness skin defect wounds in mice]

Objective: To explore the properties of gelatin-polyethylene glycol hydrogel loaded with silver nanoparticle (AgNP) Chlorella (hereinafter referred to as the composite hydrogel) and its effects on healing of infected full-thickness skin defect wounds in mice. Methods: The research was an experimental research. The simple gelatin-polyethylene glycol hydrogel (hereinafter referred to as the simple hydrogel) and the composite hydrogel were prepared, and the appearance and injectability of the two hydrogels were observed at 55 and 37 ℃, and under the irradiation of 808 nm near-infrared light, respectively. An electronic universal testing machine was employed to assess the tensile and compressive stress-strain properties of both types of hydrogels at room temperature. Additionally, the cyclic compressive stress-strain properties of the composite hydrogel were examined at 80% of the maximum compressive stress. Staphylococcus aureus or Escherichia coli solution was added to phosphate buffer solution (PBS), simple hydrogel, and composite hydrogel, respectively. The part of composite hydrogel containing Staphylococcus aureus or Escherichia coli solution was irradiated with near-infrared light for 5 minutes. After each sample was incubated for 6 h, the dilution plating method was used to detect and calculate the mortality rates of the two bacteria at 24 h of culture (n=5). The discarded foreskin tissue was taken from a 6-year-old healthy boy admitted to the Department of Urology of the First Affiliated Hospital of Naval Medical University for circumcision. Primary human fibroblasts (HFbs) were isolated using the enzyme extraction method, routinely cultured to the 3rd to 6th passages for subsequent cellular experiments. Composite hydrogel extracts with final mass concentrations of 100.0, 50.0, 25.0, 12.5, and 0 mg/mL were respectively prepared and used to culture HFbs, and the cell proliferation after 24 h of culture was detected using a cell counting kit 8 (n=3). A total of twenty 6-8 weeks old C57BL/6J female mice were utilized, and a full-thickness skin defect was surgically created on the back of each mouse. The wounds were infected with Staphylococcus aureus solution. The infected mice were divided into blank control group, simple hydrogel group, composite hydrogel group, and combined treatment group according to the random number table, and the wounds were treated with PBS, simple hydrogel, composite hydrogel, and composite hydrogel+light irradiation (under the irradiation of 808 nm near-infrared light for 5 min), respectively, with 5 mice in each group. On post injury day (PID) 0 (immediately after the first wound treatment), 3, 7, and 14, an overall assessment of wound exudation and healing were conducted, and the wound healing rates on PID 7 and 14 were calculated (n=5). On PID 14, hematoxylin-eosin staining was performed to observe histopathological changes in the mouse wound. Results: Both simple hydrogel and composite hydrogel were in a solution state at 55 ℃ and transition to a gel state when cooling to 37 ℃. After the two hydrogels were irradiated by near-infrared light, only the composite hydrogel reheated up and returned to the solution state again with injectability. The maximum tensile stress of the composite hydrogel was up to 301.42 kPa, with a corresponding strain of 87.19%; the maximum compressive stress was up to 413.79 kPa, with a corresponding strain of 91.67%, which was similar to the tensile and compressive properties of the simple hydrogel. After 10 compression cycles, the maximum compressive stress of the composite hydrogel still reached 84.1% of the first compressive stress. After 24 h of culture, the mortality rate of Staphylococcus aureus treated with simple hydrogel was significantly higher than that treated with PBS (P<0.05); the mortality rates of Escherichia coli and Staphylococcus aureus treated with composite hydrogel alone were significantly higher than those treated with simple hydrogel (P<0.05); the mortality rates of Escherichia coli and Staphylococcus aureus treated with composite hydrogel+light irradiation were significantly higher than those treated with composite hydrogel alone (P<0.05). After 24 h of culture, compared with that cultured in composite hydrogel immersion solution with final mass concentration of 0 mg/mL, the proliferation activity of HFbs cultured in composite hydrogel immersion solution with final mass concentrations of 25.0 and 50.0 mg/mL was significantly enhanced (P<0.05), while the proliferation activity of HFbs cultured in composite hydrogel immersion solution with final mass concentration of 100 mg/mL was significantly decreased (P<0.05). On PID 0 and 3, more purulent secretions were seen in the wounds of mice in blank control group and simple hydrogel group, while only a small amount of exudate was observed in the wounds of mice in composite hydrogel group, and no obvious infection was observed in the wounds of mice in combined treatment group. On PID 7 and 14, the wound healing rates of mice in simple hydrogel group were significantly higher than those in blank control group (P<0.05); the wound healing rates of mice in composite hydrogel group were significantly higher than those in simple hydrogel group (P<0.05); the wound healing rates in combined treatment group were significantly higher than those in composite hydrogel group (P<0.05). On PID 14, the wounds of mice in blank control group exhibited a high infiltration of inflammatory cells with no new epithelial layer observed; the wounds of mice in simple hydrogel group displayed a short length of newly formed epithelium with a small amount of inflammatory cells; the wounds of mice in composite hydrogel group exhibited continuous formation of new epithelium and a large amount of immature granulation tissue; the wounds of mice in combined treatment group showed continuous epithelialization with less immature granulation tissue. Conclusions: The prepared composite hydrogel exhibits excellent thermosensitivity, photothermal properties, and injectability, as well as excellent mechanical properties, antibacterial properties, and biocompatibility, and can promote the healing of infected full-thickness skin defect wounds in mice.

The expression of squalene epoxidase in human gastric cancer and its clinical significance

Context

Squalene epoxidase (SQLE) is overexpressed in a variety of tumors, which may play an important role in their tumorigenesis, development, and prognosis.

Aims

The aim of this study is to investigate the expression of SQLE and explore its clinicopathological significance in gastric cancer.

Settings and Design

The correlation between its positive expression and the pathological characteristics of patients (such as sex, age, tumor size, survival, tumor differentiation, TNM staging, and lymph node metastasis) was analyzed.

Materials and Methods

Immunohistochemical method was used to detect its expression in 107 cases of gastric carcinoma and 34 cases of tumor-adjacent tissues.

Statistical Analysis Used

Counting data were analyzed by Chi-square test. Its overall survival was analyzed by Kaplan-Meier method and log-rank test. Its hazard factors were analyzed by Cox multivariate analysis.

Results

The positive rate of SQLE in gastric cancer is 67.3%, which is higher than that in tumor-adjacent tissues (17.6%), <0.001. Expression of SQLE is closely related to tumor differentiation, TNM staging and lymph node metastasis (P = 0.030, P = 0.009, and P = 0.011, respectively). Furthermore, compared with those low expression of SQLE, the patients of overexpression had worse overall survival by Kaplan-Meier analysis (P = 0.025). Cox multivariate analysis shows that lymph node metastasis, tumor differentiation, SQLE, and TNM staging are independent factors for prognosis of gastric cancer (P = 0.003, 0.020, 0.018, and P = 0.001 respectively).

Conclusions

SQLE is overexpressed in gastric cancer. It could be used for the diagnosis and prognosis of the gastric cancer patients.

Allicin enhances the radiosensitivity of colorectal cancer cells via inhibition of NF-κB signaling pathway

Radioresistance is an important factor affecting the radiotherapy effect of colorectal cancer (CRC). Allicin is a versatile sulfur-containing organic compound extracted from garlic (Allium sativum L.), which has many pharmacological effects. However, the effect of allicin on the sensitivity of CRC radiotherapy has not been confirmed. The present study is to observe the radiosensitivity effects of allicin and to explore its mechanism in CRC radiotherapy. The proliferation inhibition effects of allicin combined with X-ray radiotherapy in HCT116 cells were measured by growth curve of cell and colony formation assays. The cell apoptosis was detected by Hoechst 33258 nucleus staining assay. The migration ability of cells was detected by Transwell chamber migration assay. The animal model of CRC was established in BALB/c mice via transplantation of CT26 cell, and the radiosensitization effect of allicin on CRC was detected in vivo. The mRNA expressions of NF-κB, IKKβ, and IκBα were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). The protein expressions of NF-κB, p-NF-κB, IKKβ, p-IKKβ, IκBα, and p-IκBα were detected by western blotting. Our results showed that allicin improves the sensitivity of X-ray radiotherapy in CRC, and its mechanism may be associated with inhibition of NF-κB signaling pathway. These findings suggest that allicin may be used as a potential sensitizer for tumor radiotherapy in the clinic.

[Current situation and related policies on the implementation and promotion of influenza vaccination among health care workers]

Health care workers have higher risk of influenza infection because of their occupational exposure to infected patients. Infection of the health care workers may not only result in the increasing risk of the nosocomial infection and family transmission, but also disrupt the health services due to absence from work. Health care workers were recommended as a priority group of influenza vaccinationin more than 40 countries and regions in the world. In recent years, domestic surveys show that the influenza vaccine coverage among health care workers was low. This paper outlines the current status and related policies of influenza vaccination among health care workers in China and global. Additionally, we analyzed and discussed the proper immunization strategy of influenza vaccine for medical staff in China.

Disodium Guanylate Alleviates Acute Hepatic Injury Induced by Carbon Tetrachloride Via Antioxidative Stress and Antiapoptosis In Vivo and In Vitro

Hepatic injury is one of the most common digestive system diseases worldwide in clinic. Guanylic acid or guanosine monophosphate (GMP) was an important component of nucleotides, which is mainly in the form of sodium salt (disodium guanylate, GMP-Na₂ ). However, its effect on hepatic injury has not yet been investigated. This study is to investigate the protective effects of GMP-Na₂ on acute hepatic injury induced by carbon tetrachloride (CCl₄ ), and to explore its mechanism. The hepatic injury models of mice and HL-7702 cells were induced by CCl₄ . The alanine transaminase (ALT), aspartate aminotransferase (AST), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), malondialdehyde (MDA), total antioxidant capacity (T-AOC) were determined by biochemical method. Hematoxylin-eosin staining were used to determine the morphological changes on liver tissue in mice. The mRNA and protein expressions of caspase-3, Bax, and Bcl-2 were detected by RT-PCR and Western blot analysis. Our results show that GMP-Na₂ treatment significantly decreased the activities of ALT and AST, and the levels of MDA as well as increased the levels of SOD, GSH-Px, and T-AOC. Importantly, GMP-Na₂ effectively enhanced the antiapoptosis function by upregulating Bcl-2 expression and downregulating caspase-3 and Bax expressions in vivo and in vitro. Moreover, the histopathological changes of liver tissue were obviously improved after GMP-Na₂ treatment. These findings suggest that GMP-Na₂ has protective effects on hepatic injury, and its mechanisms may be associated with antioxidative stress and antiapoptosis.

Prognostic and clinicopathologic significance of AEG-1/MTDH and E-cadherin expression in human gallbladder carcinoma

Astrocyte elevated gene-1 (AEG-1) and E-cadherin are associated with tumorigenesis and progression. The aim of this study is to investigate the expression of AEG-1 and E-cadherin in human gallbladder cancer (GBC) and explore their clinical and pathological significance. The expression of AEG-1 and E-cadherin protein were detected in 71 cases of human GBC and 22 cases of tumor-adjacent tissue by the immunohistochemical method. Our results demonstrate that the positive expression (high expression) rate of AEG-1 was 62.0% in human GBC which was higher than that in tumor-adjacent tissues (13.6%), P<0.001. The positive expression of AEG-1 protein was correlated with tumor TNM classification, histologic grade, and lymph node metastasis (P=0.037, P=0.033 and P=0.020, respectively). The positive expression rate of E-cadherin was 40.8% in GBC, which was lower than that in tumor-adjacent tissues (77.3%), P=0.003. Negative expression (Low expression) of E-Cadherin was significantly related with tumor TNM classification, histologic grade and lymphatic metastasis (P=0.028, P=0.003 and P=0.040, respectively). The expression of AEG-1 was negatively correlated with the expression of E-Cadherin (r=0.530, P<0.001). The log-rank test statistical analysis suggested that patients with positive expression of AEG-1 or negative expression of E-Cadherin protein had shorter overall survival time. Cox multivariate analysis showed that tumor TNM classification, histologic grade and lymphatic metastasis, AEG-1 and E-cadherin expression were independent factors for prognosis of GBC (P=0.013, P=0.019, P=0.001, P=0.011 and P=0.025 respectively). In conclusion, positive expression of AEG-1 and negative expression of E-Cadherin are markedly correlated with tumor TNM classification, histologic grade and lymphatic metastasis. The expression of AEG-1 was negatively correlated with the expression of E-Cadherin. Cox multivariate analysis showed that tumor TNM classification, histologic grade and lymphatic metastasis, positive expression of AEG-1 and negative expression of E-Cadherin were risk factors for prognosis of GBC. Detection of AEG-1 and E-Cadherin may be helpful to evaluate prognosis and infiltrative capability of gallbladder carcinoma.

[DS2, a newly synthetic ent-kaurane diterpenoid analog, inhibits proliferation and migration of human gastric cancer cell]

Objective: To investigate the effects and the underlying mechanism of DS2, a newly synthetic analog of natural ent-kaurane diterpenoid, on the proliferation and migration capabilities of human gastric cancer cells. Methods: MTT assay, colony formation assay and flow cytometry were used to measure the effects of DS2 on growth, apoptosis and cell cycle of several human gastric cancer cell lines. The function of DS2 in the migration was further detected by wound healing and transwell assays. The expression of migration related proteins were determined by western blot. Results: DS2 inhibited the growth of MGC-803, SGC-7901 and HGC-27 cells in a dose dependent manner. After treatment of DS2 at a concentration of 6.25 μmol/L for 24 h, the survival rates of MGC-803, SGC-7901 and HGC-27 cells were 53.87±3.05%, 55.91±6.97% and 32.41±2.64%, respectively. However, for the normal gastric epithelial cell GES-1, no obvious growth inhibition was observed. In addition, DS2 caused significant G(2)/M arrest and induced apoptosis in MGC-803 cells. Furthermore, compared with the negative control, the colony formation, wound healing rate as well as the number of migrating cells of MGC-803 were significantly decreased in a dose dependent manner after DS2 treatment. DS2 induced the expression of E-cadherin, whereas β-catenin and N-cadherin levels were downregulated in MGC-803. Conclusion: The new compound DS2 has a strong anti-cancer activity, and this study will help us to design and synthesize better diterpenoids derivatives.

Sirt3 protects dopaminergic neurons from mitochondrial oxidative stress

Age-dependent elevation in mitochondrial oxidative stress is widely posited to be a major factor underlying the loss of substantia nigra pars compacta (SNc) dopaminergic neurons in Parkinson's disease (PD). However, mechanistic links between aging and oxidative stress are not well understood. Sirtuin-3 (Sirt3) is a mitochondrial deacetylase that could mediate this connection. Indeed, genetic deletion of Sirt3 increased oxidative stress and decreased the membrane potential of mitochondria in SNc dopaminergic neurons. This change was attributable to increased acetylation and decreased activity of manganese superoxide dismutase (MnSOD). Site directed mutagenesis of lysine 68 to glutamine (K68Q), mimicking acetylation, decreased MnSOD activity in SNc dopaminergic neurons, whereas mutagenesis of lysine 68 to arginine (K68R), mimicking deacetylation, increased activity. Introduction of K68R MnSOD rescued mitochondrial redox status and membrane potential of SNc dopaminergic neurons from Sirt3 knockouts. Moreover, deletion of DJ-1, which helps orchestrate nuclear oxidant defenses and Sirt3 in mice led to a clear age-related loss of SNc dopaminergic neurons. Lastly, K68 acetylation of MnSOD was significantly increased in the SNc of PD patients. Taken together, our studies suggest that an age-related decline in Sirt3 protective function is a major factor underlying increasing mitochondrial oxidative stress and loss of SNc dopaminergic neurons in PD.

Dual Inhibition of Topoisomerase II and Tyrosine Kinases by the Novel Bis-Fluoroquinolone Chalcone-Like Derivative HMNE3 in Human Pancreatic Cancer Cells

Both tyrosine kinase and topoisomerase II (TopII) are important anticancer targets, and their respective inhibitors are widely used in cancer therapy. However, some combinations of anticancer drugs could exhibit mutually antagonistic actions and drug resistance, which further limit their therapeutic efficacy. Here, we report that HMNE3, a novel bis-fluoroquinolone chalcone-like derivative that targets both tyrosine kinase and TopII, induces tumor cell proliferation and growth inhibition. The viabilities of 6 different cancer cell lines treated with a range of HMNE3 doses were detected using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cellular apoptosis was determined using Hoechst 33258 fluorescence staining and the terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling (TUNEL) assay. The expression of activated Caspase-3 was examined by immunocytochemistry. The tyrosine kinase activity was measured with a human receptor tyrosine kinase (RTK) detection kit using a horseradish peroxidase (HRP)-conjugated phosphotyrosine (pY20) antibody as the substrate. The topoisomerase II activity was measured using agarose gel electrophoresis with the DNA plasmid pBR322 as the substrate. The expression levels of the P53, Bax, Bcl-2, Caspase-3, -8, -9, p-cSrc, c-Src and topoisomerase II proteins were detected by western blot analysis. The proliferation of five of the six cancer cell lines was significantly inhibited by HMNE3 at 0.312 to 10 μmol/L in a time- and dose-dependent manner. Treatment of the Capan-1 and Panc-1 cells with 1.6 to 3.2 μM HMNE3 for 48 h significantly increased the percentage of apoptotic cells (P<0.05), and this effect was accompanied by a decrease in tyrosine kinase activity. HMNE3 potentially inhibited tyrosine kinase activity in vitro with an IC50 value of 0.64±0.34 μmol/L in Capan-1 cells and 3.1±0.86 μmol/L in Panc-1 cells. The activity of c-Src was significantly inhibited by HMNE3 in a dose- and time-dependent manner in different cellular contexts. Compared with the control group, HMNE3 induced increased expression of cellular apoptosis-related proteins. Consistent with cellular apoptosis data, a significant decrease in topoisomerase IIβ activity was noted following treatment with HMNE3 for 24 h. Our data suggest that HMNE3 induced apoptosis in Capan-1 and Panc-1 cells by inhibiting the activity of both tyrosine kinases and topoisomerase II.

Motor neuron mitochondrial dysfunction in spinal muscular atrophy

Spinal muscular atrophy (SMA), the leading genetic cause of infant mortality, predominantly affects high metabolic tissues including motor neurons, skeletal muscles and the heart. Although the genetic cause of SMA has been identified, mechanisms underlying tissue-specific vulnerability are not well understood. To study these mechanisms, we carried out a deep sequencing analysis of the transcriptome of spinal motor neurons in an SMA mouse model, in which we unexpectedly found changes in many genes associated with mitochondrial bioenergetics. Importantly, functional measurement of mitochondrial activities showed decreased basal and maximal mitochondrial respiration in motor neurons from SMA mice. Using a reduction-oxidation sensitive GFP and fluorescence sensors specifically targeted to mitochondria, we found increased oxidative stress level and impaired mitochondrial membrane potential in motor neurons affected by SMA. In addition, mitochondrial mobility was impaired in SMA disease conditions, with decreased retrograde transport but no effect on anterograde transport. We also found significantly increased fragmentation of the mitochondrial network in primary motor neurons from SMA mice, with no change in mitochondria density. Electron microscopy study of SMA mouse spinal cord revealed mitochondria fragmentation, edema and concentric lamellar inclusions in motor neurons affected by the disease. Intriguingly, these functional and structural deficiencies in the SMA mouse model occur during the presymptomatic stage of disease, suggesting a role in initiating SMA. Altogether, our findings reveal a critical role for mitochondrial defects in SMA pathogenesis and suggest a novel target for improving tissue health in the disease.

Numb directs the subcellular localization of EAAT3 through binding the YxNxxF motif

Excitatory amino acid transporter type 3 (EAAT3, also known as SLC1A1) is a high-affinity, Na(+)-dependent glutamate carrier that localizes primarily within the cell and at the apical plasma membrane. Although previous studies have reported proteins and sequence regions involved in EAAT3 trafficking, the detailed molecular mechanism by which EAAT3 is distributed to the correct location still remains elusive. Here, we identify that the YVNGGF sequence in the C-terminus of EAAT3 is responsible for its intracellular localization and apical sorting in rat hepatoma cells CRL1601 and Madin-Darby canine kidney (MDCK) cells, respectively. We further demonstrate that Numb, a clathrin adaptor protein, directly binds the YVNGGF motif and regulates the localization of EAAT3. Mutation of Y503, N505 and F508 within the YVNGGF motif to alanine residues or silencing Numb by use of small interfering RNA (siRNA) results in the aberrant localization of EAAT3. Moreover, both Numb and the YVNGGF motif mediate EAAT3 endocytosis in CRL1601 cells. In summary, our study suggests that Numb is a pivotal adaptor protein that mediates the subcellular localization of EAAT3 through binding the YxNxxF (where x stands for any amino acid) motif.

[Jaridonin, a new diterpenoid from Isodon rubescens, induces cell cycle arrest in gastric cancer cells through activating ataxia telangiectasia mutated kinase]

OBJECTIVE

To study the effects of Jaridonin, a novel diterpenoid from isodon rubescens, on the cell cycle of human gastric cancer cells and its molecular mechanism of action.

METHODS

Flow cytometry was used to analyze the cell cycle distribution and expression of ataxia telangiectasia mutated kinase (ATM) after Jaridonin treatment. Western blot was performed to detect the expression of cell cycle-related proteins.

RESULTS

The results of flow cytometry showed that the percentages of MGC-803 cells in G(2)/M phase at 6 hours after 0, 10, 20 μmol/L Jaridonin-treatment were (10.8±2.2)%, (18.2±2.5)%, (27.3±3.2)%, respectively; those at 12 hours after Jaridonin-treatment were (12.0±1.5)%, (24.1±2.0)% and (39.7±5.2)%, respectively, indicating a G2/M phase arrest of MGC-803 cells was resulted in a time- and dose-dependent manner. The expressions of ATM, Chk1, Chk2, phosphorylated Cdc2 and CDK2 were up-regulated in the MGC-803 cells after Jaridonin treatment, while the levels of Cdc2 and CDK2 were decreased. KU-55933, an inhibitor of ATM, reversed the expression of relevant proteins and G(2)/M phase arrest induced by Jaridonin.

CONCLUSIONS

Jaridonin can significantly induce G(2)/M arrest in gastric cancer MGC-803 cells. Its mechanism may be related to the activation of ATM and Chk1/2, and inactivation of Cdc2 and CDK2 phosphorylation.

Role of PHLPP1 in inflammation response: Its loss contributes to gliomas development and progression

PH domain leucine-rich repeats protein phosphatase 1(PHLPP1) belongs to a novel family of Ser/Thr protein phosphatases: PHLPP serves as tumor suppressor in several cancers. However, little knowledge about the expression of PHLPP1 in human glioma tumor tissue and its role in inflammation response in glioma cells was known. Glioma samples were obtained from a total of 37 patients including 16 males and 21 females with surgical removal of the brain tumor. PHLPP1 protein and inflammatory cytokines were measured by Western blot analysis and immunohistochemistry while mRNA was determined by RT-PCR. The levels of inflammatory cytokines including TNF-α, IL-17, IL-1β in U251 glioma cells were evaluated by siRNA PHLPP1 and PHLPP1 addition. The loss of PHLPP1 expression occurs at high frequency in human gliomas. The highest mean values of PHLPP1 mRNA and protein were found in non-glioma brain tissues whereas the lowest mean values were found in those in glioblastoma with an increase of TNF-α, IL-17, IL-1β (p<0.05). PHLPP1 expression in human glioma was associated negatively with the severity of the tumor and inflammatory cytokines. siRNA PHLPP1 could increase the levels of inflammatory cytokines in U251 glioma cells while PHLPP1 addition could inhibit significantly inflammatory cytokines. We concluded that PHLPP1 played a suppression role in inflammatory response of glioma. The present study indicated that PHLPP1 could be used as a predictor for the prediction of the patients or as a therapeutic target for the treatment of human glioma.

Impaired Autophagy and Defective Mitochondrial Function: Converging Paths on the Road to Motor Neuron Degeneration

Selective motor neuron degeneration is a hallmark of amyotrophic lateral sclerosis (ALS). Around 10% of all cases present as familial ALS (FALS), while sporadic ALS (SALS) accounts for the remaining 90%. Diverse genetic mutations leading to FALS have been identified, but the underlying causes of SALS remain largely unknown. Despite the heterogeneous and incompletely understood etiology, different types of ALS exhibit overlapping pathology and common phenotypes, including protein aggregation and mitochondrial deficiencies. Here, we review the current understanding of mechanisms leading to motor neuron degeneration in ALS as they pertain to disrupted cellular clearance pathways, ATP biogenesis, calcium buffering and mitochondrial dynamics. Through focusing on impaired autophagic and mitochondrial functions, we highlight how the convergence of diverse cellular processes and pathways contributes to common pathology in motor neuron degeneration.

The survival motor neuron gene smn-1 interacts with the U2AF large subunit gene uaf-1 to regulate Caenorhabditis elegans lifespan and motor functions

Spinal muscular atrophy (SMA), the most frequent human congenital motor neuron degenerative disease, is caused by loss-of-function mutations in the highly conserved survival motor neuron gene SMN1. Mutations in SMN could affect several molecular processes, among which aberrant pre-mRNA splicing caused by defective snRNP biogenesis is hypothesized as a major cause of SMA. To date little is known about the interactions of SMN with other splicing factor genes and how SMN affects splicing in vivo. The nematode Caenorhabditis elegans carries a single ortholog of SMN, smn-1, and has been used as a model for studying the molecular functions of SMN. We analyzed RNA splicing of reporter genes in an smn-1 deletion mutant and found that smn-1 is required for efficient splicing at weak 3' splice sites. Genetic studies indicate that the defective lifespan and motor functions of the smn-1 deletion mutants could be significantly improved by mutations of the splicing factor U2AF large subunit gene uaf-1. In smn-1 mutants we detected a reduced expression of U1 and U5 snRNAs and an increased expression of U2, U4 and U6 snRNAs. Our study verifies an essential role of smn-1 for RNA splicing in vivo, identifies the uaf-1 gene as a potential genetic modifier of smn-1 mutants, and suggests that SMN-1 has multifaceted effects on the expression of spliceosomal snRNAs.

Excessive Wnt/beta-catenin signaling promotes midbrain floor plate neurogenesis, but results in vacillating dopamine progenitors

The floor plate (FP), a ventral midline structure of the developing neural tube, has differential neurogenic capabilities along the anterior-posterior axis. The midbrain FP, unlike the hindbrain and spinal cord floor plate, is highly neurogenic and produces midbrain dopaminergic (mDA) neurons. Canonical Wnt/beta-catenin signaling, at least in part, is thought to account for the difference in neurogenic capability. Removal of beta-catenin results in mDA progenitor specification defects as well as a profound reduction of neurogenesis. To examine the effects of excessive Wnt/beta-catenin signaling on mDA specification and neurogenesis, we have analyzed a model wherein beta-catenin is conditionally stabilized in the Shh+domain. Here, we show that the Foxa2+/Lmx1a+ domain is extended rostrally in mutant embryos, suggesting that canonical Wnt/beta-catenin signaling can drive FP expansion along the rostrocaudal axis. Although excess canonical Wnt/beta-catenin signaling generally promotes neurogenesis at midbrain levels, less tyrosine hydroxylase (Th)+, mDA neurons are generated, particularly impacting the Substantia Nigra pars compacta. This is likely because of improper progenitor specification. Excess canonical Wnt/beta-catenin signaling causes downregulation of net Lmx1b, Shh and Foxa2 levels in mDA progenitors. Moreover, these progenitors assume a mixed identity to that of Lmx1a+/Lmx1b+/Nkx6-1+/Neurog1+ progenitors. We also show by lineage tracing analysis that normally, Neurog1+ progenitors predominantly give rise to Pou4f1+ neurons, but not Th+ neurons. Accordingly, in the mutant embryos, Neurog1+ progenitors at the midline generate ectopic Pou4f1+ neurons at the expense of Th+ mDA neurons. Our study suggests that an optimal dose of Wnt/beta-catenin signaling is critical for proper establishment of the mDA progenitor character. Our findings will impact embryonic stem cell protocols that utilize Wnt pathway reagents to derive mDA neuron models and therapeutics for Parkinson's disease.

Non-aggregating tau phosphorylation by cyclin-dependent kinase 5 contributes to motor neuron degeneration in spinal muscular atrophy

Mechanisms underlying motor neuron degeneration in spinal muscular atrophy (SMA), the leading inherited cause of infant mortality, remain largely unknown. Many studies have established the importance of hyperphosphorylation of the microtubule-associated protein tau in various neurodegenerative disorders, including Alzheimer's and Parkinson's diseases. However, tau phosphorylation in SMA pathogenesis has yet to be investigated. Here we show that tau phosphorylation on serine 202 (S202) and threonine 205 (T205) is increased significantly in SMA motor neurons using two SMA mouse models and human SMA patient spinal cord samples. Interestingly, phosphorylated tau does not form aggregates in motor neurons or neuromuscular junctions (NMJs), even at late stages of SMA disease, distinguishing it from other tauopathies. Hyperphosphorylation of tau on S202 and T205 is mediated by cyclin-dependent kinase 5 (Cdk5) in SMA disease condition, because tau phosphorylation at these sites is significantly reduced in Cdk5 knock-out mice; genetic knock-out of Cdk5 activating subunit p35 in an SMA mouse model also leads to reduced tau phosphorylation on S202 and T205 in the SMA;p35(-/-) compound mutant mice. In addition, expression of the phosphorylation-deficient tauS202A,T205A mutant alleviates motor neuron defects in a zebrafish SMA model in vivo and mouse motor neuron degeneration in culture, whereas expression of phosphorylation-mimetic tauS202E,T205E promotes motor neuron defects. More importantly, genetic knock-out of tau in SMA mice rescues synapse stripping on motor neurons, NMJ denervation, and motor neuron degeneration in vivo. Altogether, our findings suggest a novel mechanism for SMA pathogenesis in which hyperphosphorylation of non-aggregating tau by Cdk5 contributes to motor neuron degeneration.

Molecular mechanisms and animal models of spinal muscular atrophy

Spinal muscular atrophy (SMA), the leading genetic cause of infant mortality, is characterized by the degeneration of spinal motor neurons and muscle atrophy. Although the genetic cause of SMA has been mapped to the Survival Motor Neuron1 (SMN1) gene, mechanisms underlying selective motor neuron degeneration in SMA remain largely unknown. Here we review the latest developments and our current understanding of the molecular mechanisms underlying SMA pathogenesis, focusing on the animal model systems that have been developed, as well as new diagnostic and treatment strategies that have been identified using these model systems. This article is part of a special issue entitled: Neuromuscular Diseases: Pathology and Molecular Pathogenesis.

Role of osteopontin in the regulation of human bladder cancer proliferation and migration in T24 cells

Osteopontin (OPN), a secreted acid glycoprotein with a variety of functions, promotes tumor proliferation, differentiation, invasion and metastasis. The aim of the current study was to investigate whether OPN may serve as a potential therapeutic target for human bladder cancer. RNA interference (RNAi) was performed to downregulate the expression of the OPN gene in T24 human bladder cancer cells. The mRNA and protein expression levels of OPN following RNAi were determined using reverse transcription‑quantitative polymerase chain reaction and western blot analysis, respectively. In addition, the cell cycle progression, apoptosis and proliferation were investigated using by flow cytometric analysis and MTT assay. The cell invasion ability was measured using a Matrigel transwell assay. The mRNA and protein expression levels of OPN were found to be significantly downregulated following RNAi. The proliferation and invasion of T24 cells were significantly inhibited in vitro. In conclusion, RNAi‑targeting OPN may inhibit the proliferation, invasion and tumorigenicity of human bladder cancer cells. Therefore, OPN may serve as a potential therapeutic target for human bladder cancer.

HAP1 gene expression is associated with radiosensitivity in breast cancer cells

OBJECTIVES

The purpose of this study was to investigate the relationship between huntingtin-associated protein1 (HAP1) gene and radiation therapy of breast cancer cells.

METHODS

HAP1 gene was transfected into breast cancer MCF-7 cells, which was confirmed by quantitative reverse transcription-polymerase chain reaction analysis (qRT-PCR) and Western blot in vitro. The changes of cell radiosensitivity were assessed by colony formation assay. Apoptosis were examined by flow cytometry. The expressions of two radiation-induced genes were evaluated by Western blot. Tumor growth was investigated in nude mice xenograft models in vivo.

RESULTS

Our data showed that HAP1 gene expression was significantly increased in HAP1-transfected MCF-7 cells in comparison with the parental cells or negative control cells. The survival rate in MCF-7/HAP1 cells was significantly decreased after irradiation (0, 2, 4, 6, 8Gy), compared to cells in MCF-7 and MCF-7/Pb groups in vitro. HAP1 gene increased apoptosis in MCF-7 cells after irradiation. Additionally, the tumor volume and weight in MCF-7/HAP1+RT group were observably lower than in MCF-7/HAP1 group and MCF-7/Pb+RT group.

CONCLUSION

The present study indicated that HAP1 gene expression was related to the radiosensitivity of breast cancer cells and may play an important role in the regulation of cellular radiosensitivity.

Effect of Furin inhibitor on lung adenocarcinoma cell growth and metastasis

Background

To investigate the mechanisms of lung adenocarcinoma cell metastasis and provide a theoretical basis for the in-depth study of lung adenocarcinoma.

Methods

A549 cells are incubated with different concentrations of Furin inhibitor for indicated times. The proliferation and migration were confirmed with MTT, colony formation, wound Healing and Transwell assayes. Hochest 33342 / PI double staining was used to detect apoptosis. Cell migration and apoptosis associated proteins were analysed by enzyme-linked immunosorbent assay (ELISA) and western blot.

Results

We have found that Furin inhibitor play a significant role in inhibition A549 cell growth. And we also found cell migration was inhibited significantly upon Furin inhibitor treatment.

Conclusion

The proliferration and migration of A549 cell were inhibited by Furin inbitor through down-regulation the expression of migration and apoptosis related proteins.

Immunosenescence and age-related viral diseases

Immunosenescence is described as a decline in the normal functioning of the immune system associated with physiologic ageing. Immunosenescence contributes to reduced efficacy to vaccination and increased susceptibility to infectious diseases in the elderly. Extensive studies of laboratory animal models of ageing or donor lymphocyte analysis have identified changes in immunity caused by the ageing process. Most of these studies have identified phenotypic and functional changes in innate and adaptive immunity. However, it is unclear which of these defects are critical for impaired immune defense against infection. This review describes the changes that occur in innate and adaptive immunity with ageing and some age-related viral diseases where defects in a key component of immunity contribute to the high mortality rate in mouse models of ageing.

In ovo electroporation in chick midbrain for studying gene function in dopaminergic neuron development

Dopaminergic neurons located in the ventral midbrain control movement, emotional behavior, and reward mechanisms. The dysfunction of ventral midbrain dopaminergic neurons is implicated in Parkinson's disease, Schizophrenia, depression, and dementia. Thus, studying the regulation of midbrain dopaminergic neuron differentiation could not only provide important insight into mechanisms regulating midbrain development and neural progenitor fate specification, but also help develop new therapeutic strategies for treating a variety of human neurological disorders. Dopaminergic neurons differentiate from neural progenitors lining the ventricular zone of embryonic ventral midbrain. The development of neural progenitors is controlled by gene expression programs. Here we report techniques utilizing electroporation to express genes specifically in the midbrain of Hamburger Hamilton (HH) stage 11 (thirteen somites, 42 hours) chick embryos. The external development of chick embryos allows for convenient experimental manipulations at specific embryonic stages, with the effects determined at later developmental time points. Chick embryonic neural tubes earlier than HH stage 13 (nineteen somites, 48 hours) consist of multipotent neural progenitors that are capable of differentiating into distinct cell types of the nervous system. The pCAG vector, which contains both a CMV promoter and a chick β-actin enhancer, allows for robust expression of Flag or other epitope-tagged constructs in embryonic chick neural tubes. In this report, we emphasize special measures to achieve regionally restricted gene expression in embryonic midbrain dopaminergic neuron progenitors, including how to inject DNA constructs specifically into the embryonic midbrain region and how to pinpoint electroporation with small custom-made electrodes. Analyzing chick midbrain at later stages provides an excellent in vivo system for plasmid vector-mediated gain-of-function and loss-of-function studies of midbrain development. Modification of the experimental system may extend the assay to other parts of the nervous system for performing fate mapping analysis and for investigating the regulation of gene expression.

The tyrosine kinase c-Src directly mediates growth factor-induced Notch-1 and Furin interaction and Notch-1 activation in pancreatic cancer cells

The proteolytic activity of Furin responsible for processing full length Notch-1 (p300) plays a critical role in Notch signaling. The amplitude and duration of Notch activity can be regulated at various points in the pathway, but there has been no report regarding regulation of the Notch-1-Furin interaction, despite its importance. In the present study, we found that the Notch-1-Furin interaction is regulated by the non-receptor tyrosine kinase, c-Src. c-Src and Notch-1 are physically associated, and this association is responsible for Notch-1 processing and activation. We also found that growth factor TGF-α, an EGFR ligand, and PDGF-BB, a PDGFR ligand, induce the Notch-1-Furin interaction mediated by c-Src. Our results support three new and provocative conclusions: (1) The association between Notch-1 and Furin is a well-regulated process; (2) Extracellular growth factor signals regulate this interaction, which is mediated by c-Src; (3) There is cross-talk between the plasma growth factor receptor-c-Src and Notch pathways. Co-localization of Notch-1 and c-Src was confirmed in xenograft tumor tissues and in the tissues of pancreatic cancer patients. Our findings have implications for the mechanism by which the Notch and growth factor receptor-c-Src signaling pathways regulate carcinogenesis and cancer cell growth.

Regulation of motor neuron specification by phosphorylation of neurogenin 2

The mechanisms by which proneural basic helix-loop-helix (bHLH) factors control neurogenesis have been characterized, but it is not known how they specify neuronal cell-type identity. Here, we provide evidence that two conserved serine residues on the bHLH factor neurogenin 2 (Ngn2), S231 and S234, are phosphorylated during motor neuron differentiation. In knockin mice in which S231 and S234 of Ngn2 were mutated to alanines, neurogenesis occurs normally, but motor neuron specification is impaired. The phosphorylation of Ngn2 at S231 and S234 facilitates the interaction of Ngn2 with LIM homeodomain transcription factors to specify motor neuron identity. The phosphorylation-dependent cooperativity between Ngn2 and homeodomain transcription factors may be a general mechanism by which the activities of bHLH and homeodomain proteins are temporally and spatially integrated to generate the wide diversity of cell types that are a hallmark of the nervous system.

Out-of-plane temperature-dependent resistivity studies on Tl-based superconductors

Temperature-dependent resistivities in the ab-plane and c-axis of Tl-based cuprates have been measured. Unlike the ab-plane properties, which are metallic, c-axis transport is semiconductor-like in the normal state for Tl(2)Ba(2)Ca(2)Cu(3)O(x) (Tl-2223) and Tl(2)Ba(2)CaCu(2)O(x) (Tl-2212). In contrast, for Tl(2)Ba(2)CuO(x) (Tl-2201), transport is metal-like in both the in-plane and the c-axis. For multi-layered cuprates, transport properties along the c-axis could be described by a tunnelling model, whereas for single-layered compound Tl-2201 it would be easier for the out-of-plane transport behaviour to be coherent since the there are no insulating Ca layers in its structure. Moreover, combining the studies on Bi-2201, which has an insulating behaviour for the out-of-plane resistivity, we suggest that the Tl-O layers in Tl-based superconductors could be conducting, unlike the weakly correlated Bi-O layers in Bi-based cuprates.

Requirement of SRC-family tyrosine kinases in fat accumulation

Src-family tyrosine kinases mediate many receptor signals to various biological responses. Here we investigate the requirement of Src-family tyrosine kinases in adipogenesis. The biochemical mechanism by which insulin induces adipogenesis, converting fibroblast cells to adipocytes, is not clear. We show that fibroblast cells deficient of three ubiquitously expressed Src-family members (Src, Yes, and Fyn), SYF cells, are refractory to hormonally induced fat accumulation. The defect is rescued by reintroduction of c-Src into SYF cells. Furthermore, Src-family tyrosine kinases are required in the early steps of insulin signaling; it is responsible for the tyrosine phosphorylation of adaptor protein c-Cbl. Deficiency of c-Cbl blocked adipogenesis. These genetic and biochemical data clearly demonstrate that Src-family tyrosine kinases serve as a critical signal relay, via phosphorylation of c-Cbl, for fat accumulation, and provide potential new strategies for treating obesity.

Infrared probe of the electronic structure and charge dynamics of Na0.7CoO2

We present measurements of the optical spectra on Na(0.7)CoO(2) single crystals. The optical conductivity shows two broad interband transition peaks at 1.6 eV and 3.1 eV, and a weak midinfrared peak at 0.4 eV. The intraband response of conducting carriers is different from that of a simple Drude metal. A peak at low but finite frequency is observed, which shifts to higher frequencies with increasing temperature, even though the dc resistivity is metallic. The origin of the interband transitions and the low-frequency charge dynamics have been discussed and compared with other experiments.

Low-dose alemtuzumab (Campath®) in myeloablative allogeneic stem cell transplantation for CD52-positive malignancies: decreased incidence of acute graft-versus-host-disease with unique pharmacokinetics

Alemtuzumab is effective in reducing the risk of acute graft-versus-host disease (GVHD) after allogeneic stem cell transplantation (ASCT). Alemtuzumab may also delay immune reconstitution and reduce graft-versus-leukemia effects. The optimal dose has not been established. We investigated engraftment, acute GVHD incidence and severity, and pharmacokinetics of alemtuzumab associated with the use of low-dose alemtuzumab/cyclophosphamide/total body irradiation and ASCT for patients with aggressive CD52-positive hematologic malignancies. In all, 12 patients were treated. Alemtuzumab 10 mg daily on days -7 to -3 was given intravenously. Tacrolimus and methotrexate were used for GVHD prophylaxis. Alemtuzemab was not detected in any of the 36 sequential serum samples tested between days -1 and +21 of transplant. All patients engrafted rapidly; the median time to an absolute neutrophil count >0.5 x 10(9)/l was 14 days (range 11-17 days), and the median time to a platelet count >20 x 10(9)/l was 16 days (range 6-30 days). By 1 month after transplant, nine patients had 100% donor chimerism, while three had mixed donor chimerism. At 3 months, 11 had achieved 100% donor chimerism. No cases of grade III/IV acute GVHD occurred. At a median follow-up interval of 14.7 months (range 4-24), seven patients remained alive, and five remained free of disease.

Src-mediated RGS16 tyrosine phosphorylation promotes RGS16 stability

The amplitude of signaling evoked by stimulation of G protein-coupled receptors may be controlled in part by the GTPase accelerating activity of the regulator of G protein signaling (RGS) proteins. In turn, subcellular targeting, protein-protein interactions, or post-translational modifications such as phosphorylation may shape RGS activity and specificity. We found previously that RGS16 undergoes tyrosine phosphorylation on conserved tyrosine residues in the RGS box. Phosphorylation on Tyr(168) was mediated by the epidermal growth factor receptor (EGFR). We show here that endogenous RGS16 is phosphorylated after epidermal growth factor stimulation of MCF-7 cells. In addition, p60-Src or Lyn kinase phosphorylated recombinant RGS16 in vitro, and RGS16 underwent phosphorylation in the presence of constitutively active Src (Y529F) in EGFR(-) CHO-K1 cells. Blockade of endogenous Src activity by selective inhibitors attenuated RGS16 phosphorylation induced by pervanadate or receptor stimulation. Furthermore, the rate of RGS16 degradation was reduced in cells expressing active Src or treated with pervanadate or a G protein-coupled receptor ligand (CXCL12). Induction of RGS16 tyrosine phosphorylation was associated with increased RGS16 protein levels and enhanced GAP activity in cell membranes. These results suggest that Src mediates RGS16 tyrosine phosphorylation, which may promote RGS16 stability.

Survival factor-mediated BAD phosphorylation raises the mitochondrial threshold for apoptosis

Growth factor suppression of apoptosis correlates with the phosphorylation and inactivation of multiple proapoptotic proteins, including the BCL-2 family member BAD. However, the physiological events required for growth factors to block cell death are not well characterized. To assess the contribution of BAD inactivation to cell survival, we generated mice with point mutations in the BAD gene that abolish BAD phosphorylation at specific sites. We show that BAD phosphorylation protects cells from the deleterious effects of apoptotic stimuli and attenuates death pathway signaling by raising the threshold at which mitochondria release cytochrome c to induce cell death. These findings establish a function for endogenous BAD phosphorylation, and elucidate a mechanism by which survival kinases block apoptosis in vivo.

Csk, a critical link of g protein signals to actin cytoskeletal reorganization

Heterotrimeric G proteins can signal to reorganize the actin cytoskeleton, but the mechanism is unclear. Here we report that, in tyrosine kinase Csk-deficient mouse embryonic fibroblast cells, G protein (Gbetagamma, Galpha(12), Galpha(13), and Galpha(q))-induced, and G protein-coupled receptor-induced, actin stress fiber formation was completely blocked. Reintroduction of Csk into Csk-deficent cells restored the G protein-induced actin stress fiber formation. Chemical rescue experiments with catalytic mutants of Csk demonstrated that the catalytic activity of Csk was required for this process. Furthermore, we uncovered that Gbetagamma can both translocate Csk to the plasma membrane and directly increase Csk kinase activity. Our genetic and biochemical studies demonstrate that Csk plays a critical role in mediating G protein signals to actin cytoskeletal reorganization.

Novel regulation and function of Src tyrosine kinase

Src tyrosine kinase is a critical signal transducer that modulates a wide variety of cellular functions. Misregulation of Src leads to cell transformation and cancer. Heterotrimeric guanine-nucleotide-binding proteins (G proteins) are another group of signaling molecules that transduce signals from cell-surface receptors to generate physiological responses. Recently, it was discovered that G alpha s and G alpha i could directly stimulate Src family tyrosine kinase activity. This novel regulation of Src tyrosine kinase by G proteins provides insights into the adenylyl cyclase-independent signaling mechanisms involved in ligand-induced receptor desensitization, internalization and other physiological processes.

RGS-PX1, a GAP for GalphaS and sorting nexin in vesicular trafficking

Heterotrimeric GTP-binding proteins (G proteins) control cellular functions by transducing signals from the outside to the inside of cells. Regulator of G protein signaling (RGS) proteins are key modulators of the amplitude and duration of G protein-mediated signaling through their ability to serve as guanosine triphosphatase-activating proteins (GAPs). We have identified RGS-PX1, a Galpha(s)-specific GAP. The RGS domain of RGS-PX1 specifically interacted with Galpha(s), accelerated its GTP hydrolysis, and attenuated Galpha(s)-mediated signaling. RGS-PX1 also contains a Phox (PX) domain that resembles those in sorting nexin (SNX) proteins. Expression of RGS-PX1 delayed lysosomal degradation of the EGF receptor. Because of its bifunctional role as both a GAP and a SNX, RGS-PX1 may link heterotrimeric G protein signaling and vesicular trafficking.

Urinary thiodiglycolic acid levels for vinyl chloride monomer-exposed polyvinyl chloride workers

Thiodiglycolic acid (TdGA) is the major metabolite of vinyl chloride monomer (VCM) detected in human urine. Although urinary TdGA has been reported to be associated with ambient VCM exposure, the relationship between urinary TdGA and a low level of air VCM is not clear. Questionnaires were administered to 16 polyvinyl chloride manufacturing workers to obtain a detailed history of occupation and lifestyle. For each worker, personal air monitoring for VCM was performed and a time-weighted average for VCM exposure was calculated. The urinary TdGA levels at the end of a work shift, and at the commencement of the next shift, were also assessed for each worker. Urine analysis revealed that TdGA levels at the beginning of the next shift were higher than those at the end of that shift. Workers experiencing a VCM exposure greater than 5 ppm in air revealed a urinary TdGA level significantly greater than those experiencing a VCM exposure of less than 5 ppm (P < 0.05). The best fit of regression for urinary TdGA on air VCM was Y = 1.06 + 0.57X for urine collected at the commencement of the following work shift, where X is the air VCM concentration and Y is the urinary TdGA concentration (r2 = 0.65, P < 0.01). We conclude that the urinary TdGA level is best detected at the commencement of the next shift and that it can be used as an exposure marker for polyvinyl chloride workers when the air VCM level to which they are exposed is greater than 5 ppm.

Src tyrosine kinase is a novel direct effector of G proteins

Heterotrimeric G proteins transduce signals from cell surface receptors to modulate the activity of cellular effectors. Src, the product of the first characterized proto-oncogene and the first identified protein tyrosine kinase, plays a critical role in the signal transduction of G protein-coupled receptors. However, the mechanism of biochemical regulation of Src by G proteins is not known. Here we demonstrate that Galphas and Galphai, but neither Galphaq, Galpha12 nor Gbetay, directly stimulate the kinase activity of downregulated c-Src. Galphas and Galphai similarly modulate Hck, another member of Src-family tyrosine kinases. Galphas and Galphai bind to the catalytic domain and change the conformation of Src, leading to increased accessibility of the active site to substrates. These data demonstrate that the Src family tyrosine kinases are direct effectors of G proteins.

Apoptotic signaling through the beta -adrenergic receptor. A new Gs effector pathway

Stimulation of beta-adrenergic receptor normally results in signaling by the heterotrimeric G protein G(s), leading to the activation of adenylyl cyclase, production of cAMP, and activation of cAMP-dependent protein kinase (PKA). Here we report that cell death of thymocytes can be induced after stimulation of beta-adrenergic receptor, or by addition of exogenous cAMP. Apoptotic cell death in both cases was observed with the appearance of terminal deoxynucleotidyl transferase-mediated UTP end labeling reactivity and the activation of caspase-3 in S49 T cells. Using thymocytes deficient in either Galpha(s) or PKA, we find that engagement of beta-adrenergic receptors initiated a Galpha(s)-dependent, PKA-independent pathway leading to apoptosis. This alternative pathway involves Src family tyrosine kinase Lck. Furthermore, we show that Lck protein kinase activity can be directly stimulated by purified Galpha(s). Our data reveal a new signaling pathway for Galpha(s), distinct from the classical PKA pathway, that accounts for the apoptotic action of beta-adrenergic receptors.

Identification of the binding site for Gqalpha on its effector Bruton's tyrosine kinase

Heterotrimeric G proteins and tyrosine kinases are two major cellular signal transducers. Although G proteins are known to activate tyrosine kinases, the activation mechanism is not clear. Here, we demonstrate that G protein Gqalpha binds directly to the nonreceptor Bruton's tyrosine kinase (Btk) to a region composed of a Tec-homology (TH) domain and a sarcoma virus tyrosine kinase (Src)-homology 3 (SH3) domain both in vitro and in vivo. Only active GTP-bound Gqalpha, not inactive GDP-bound Gqalpha, can bind to Btk. Mutations of Btk that disrupt its ability to bind Gqalpha also eliminate Btk stimulation by Gqalpha, suggesting that this interaction is important for Btk activation. Remarkably, the structure of this TH (including a proline-rich sequence) -SH3 fragment of the Btk family of tyrosine kinases shows an intramolecular interaction. Furthermore, the crystal structure of the Src family of tyrosine kinases reveals that the intramolecular interaction of SH3 and its ligand is the major determining factor keeping the kinase inactive. Thus, we propose an activation model that entails binding of Gqalpha to the TH-SH3 region, thereby disrupting the TH-SH3 intramolecular interaction and activating Btk.

Effect of docosahexaenoic acid on the synthesis of phosphatidylserine in rat brain in microsomes and C6 glioma cells

Docosahexaenoic acid (22:6n-3) is the major polyunsaturated fatty acid (PUFA) in the CNS and accumulates particularly in phosphatidylserine (PS). We have investigated the effect of the 22:6n-3 compositional status on the synthesis of PS. The fatty acid composition of brain microsomes from offspring of rats artificially reared on an n-3-deficient diet showed a dramatic reduction of 22:6n-3 content (1.7 +/- 0.1%) when compared with control animals (15.0 +/- 0.2%). The decrease was accompanied by an increase in docosapentaenoic acid (22:5n-6) content, which replaced the 22:6n-3 phospholipids with 22:5n-6 molecular species, as demonstrated using HPLC/electrospray mass spectrometry. The n-3 deficiency did not affect the total amount of polyunsaturated phospholipids in brain microsomes; however, it was associated with a decrease in the total polyunsaturated PS content and with increased levels of 1-stearoyl-2-docosapentanoyl (18:0/22:5n-6) species, particularly in phosphatidylcholine. Incorporation of [3H]serine into PS in rat brain microsomes from n-3-deficient animals was slightly but significantly less than that of the control animals. Similarly, C6 glioma cells cultured for 24 h in 22:6n-3-supplemented media (10-40 microM) showed a significant increase in the synthesis of [3H]PS when compared with unsupplemented cells. Our data show that neuronal and glial PS synthesis is sensitive to changes in the docosahexaenoate levels of phospholipids and suggest that 22:6n-3 may be a modulator of PS synthesis.

[Effect of norepinephrine on the thermosensitive neurons in preoptic area of hypothalamus tissue slices in cold acclimatized rats]

In this work, single unit firing activities were recorded in the preoptic anterior hypothalamus (POAH) brain slices of cold acclimatized and room-temperature housed rats (CR and RR) and the effects of NE on the neuronal discharges were observed. The neurons of POAH in CR became much more sensitive to NE than that in RR (the threshold concentration of NE of CR became significantly lowered). In comparison with RR, the percentage of warm sensitive neurons that could be excited by NE was decreased and some of them even showed inhibitory responses. On the other hand, the percentage of cold sensitive neurons that could be inhibited by NE was decreased and some of them even showed excitatory responses. The percentage of thermo-insensitive neurons that could be either excited or inhibited by NE were increased.

[Adaptive changes of preoptic thermosensitive neurons in hypothalamic tissue slices of rats after long-term exposure to cold environmental temperature]

In the present work, thermosensitivity and spontaneous firing rate of 86 preoptic neurons in hypothalamic tissue slices from 20 cold acclimated rats (CR, at 5 +/- 1 degrees C for more than 3 weeks) and 127 neurons from 35 warm acclimated rats (WR, at 20 +/- 3 degrees C for the same period) were recorded and compared. The results showed that: (1) The percentage of cold-sensitive neurons in CR were higher than that in WR, the critical temperature and the lowest temperature of the spontaneous firing activity of cold-sensitive neurons in CR were also lower than that in WR. (2) Thermosensitivity and critical temperature of the warm-sensitive neurons in CR were remarkably decreased, and spontaneous firing rate under 37 degrees C was increased. (3) Spontaneous firing rate (37 degrees C) of temperature insensitive neurons in CR were conspicuously increased and the lowest temperature extended downward. These profound changes in response to long-term cold exposure suggested that plasticity of preoptic neurons was involved in the thermoregulation in cold adaptation.

Spontaneous rectus sheath hematoma during treatment of pulmonary embolism with warfarin: report of a case

We present a case of a patient suffering from acute abdomen with a palpable mass on the left lower quadrant of the abdominal wall. The clinical manifestations and plain abdomen gave the misleading diagnosis of a ventral hernia. A review of the patient history revealed the use of anticoagulants for pulmonary embolism, and as a result computed tomography (CT) was performed which provided an accurate diagnosis of rectus sheath hematoma. The probable pathogenesis is discussed.

Cloning of a cDNA encoding the small subunit of cytochrome b558 (cybS) of mitochondrial fumarate reductase (complex II) from adult Ascaris suum

Complex II in the mitochondria of the adult parasitic nematode, Ascaris suum, exhibits high fumarate reductase activity in addition to succinate dehydrogenase activity and plays a key role in the anaerobic energy metabolism of the worm. In this study, the amino acid sequence of the small subunit of cytochrome b558 (cybS) in adult complex II was deduced from the cDNA isolated by immunoscreening an A. suum muscle cDNA library. Histidine residues, which are possible heme axial ligands in cytochrome b558, were found in the second transmembrane segment of the subunit. This is the first report of the primary structure of the small subunit in the two-subunit cytochrome b in mitochondrial complex II from a multicellular eukaryote.

Specificity of polyunsaturated fatty acid release from rat brain synaptosomes

Release of specific polyunsaturated fatty acids for cell membranes may have a significant implication in biological function, considering the involvement of various fatty acids in cell signal transduction. In the present study, release of polyunsaturated fatty acids from rat brain synaptosomes by endogenous synaptosomal lipase activity was examined in comparison to that by cobra venom phospholipase A2 (Naja naja naja). Cobra venom phospholipase A2 (Naja naja naja) preferentially hydrolyzed docosahexaenoic acid (22:6n-3) from both synaptosomes and lipid mixtures containing similar classes of lipids commonly found in the brain. Arachidonic acid (20:4n-6) and oleic acid (18:1n-9) were also hydrolyzed; however, monoene species was hydrolyzed slower than were polyenoic species in synaptosomes. Phosphatidylethanolamine was the most preferred phospholipid class for release of 22:6n-3 fatty acid from both lipid mixtures and synaptosomes. In contrast to hydrolysis by cobra venom phospholipase A2, endogenous synaptosomal lipase activity preferentially hydrolyzed 20:4n-6 from rat brain synaptosomes, despite the high abundance of 22:6n-3 in synaptosomal membranes. Preferential release of 20:4n-6 was observed over a wide range of pH values and calcium concentrations. Synaptosomal 22:6 species appeared to be resistant to hydrolysis even after stimulation with various agents such as phorbolmyristate, suggesting that physiological importance of 22:6n-3 in neuronal membranes may not be as the release fatty acid.

Retroperitoneal lipoblastoma: report of one case

A one-year-old boy presented with progressive distension of the abdomen occurring over a few months. Computed tomography (CT) scan demonstrated a large, well-defined retroperitoneal mass with heterogeneous attenuation appearance and areas of low density showing as fatty substance. Slight enhancement of the soft tissue components was also noted. Reviewing of the literature indicates an accurate preoperative diagnosis of such fatty tumor is allowed by analysis of patient's age, tumor location, and characteristic CT pictures.