Recombinant erythropoietin protective and related effects on brain injury in premature infants

OBJECTIVE

The aim of this study was to investigate the protective effect of recombinant erythropoietin at different doses on brain injury in premature infants and the related effects on blood routine, liver function, intellectual development, mental development index (MDI), psychomotor development index (PDI), etc. PATIENTS AND METHODS: A total of 120 premature infants were divided into four groups, including experimental group A (n=30), experimental group B (n=30), experimental group C (n=30) and control group (n=30). The experimental group was treated with different doses of recombinant erythropoietin for brain injury protection of premature infants, while the control group with conventional methods.

RESULTS

There was no statistical significance in all test indicators of the four groups of patients before the intervention. After the intervention experiment, the S-100B index was p<0.05, and the erythropoietin (EPO) index was p<0.05. In the comparison of IL-6 indicators, the indicators of the experimental group were reduced after the comparison experiment, and there were significant differences, p<0.05. In neonatal behavior evaluation, there was a statistical difference between groups A and B and the control group (p<0.05), and no statistical significance was shown between group C and the control group (p>0.05). In the intelligence test comparison, the F value of the experimental group was 3.113 three months after treatment. After six months, the F value was 3.654. After nine months, the F value was 3.392 with p<0.05. In the comparison of blood routine indicators, the p-values of four indicators between groups were more than 0.05. In the comparison of liver function indexes, the indexes of groups A, B, and C were significantly changed before and after treatment, and the data after treatment were significantly different from those before treatment, p<0.05. In the comparison of development, there were no significant differences observed in the p-values of the two indicators of vigorous exercise and language in the experimental group.

CONCLUSIONS

Recombinant erythropoietin has a protective effect on infants with brain injury and can improve the intellectual development of premature infants, but has no significant effect on blood routine indicators. It can effectively improve the MDI, PDI, and related cytokines of premature infants, and has certain significance for the treatment of brain injury.

[Current status and challenges of anticoagulation management in extracorporeal membrane oxygenation]

The anticoagulant management of extracorporeal membrane oxygenation(ECMO) is facing great challenges. Complications related to the coagulation system such as bleeding or embolism are one of the main factors affecting the mortality of patients. How to control the dynamic balance between thrombosis and bleeding complications has become the top priority of ECMO management. This article reviews the coagulation changes during ECMO support, how to choose appropriate anticoagulant drugs and anticoagulation monitoring methods, aiming to explore the best anticoagulation strategy for ECMO patients.

POS1558-HPR INFLUENCING FACTORS ON WORK BURNOUT OF PRE-EXAMINATION AND TRIAGE NURSES UNDER THE NORMAL EPIDEMIC PREVENTION AND CONTROL

Background

Nurse is a high-risk groups work fatigue feeling, which seriously affects the quality of conventional work efficiency and bureden pressures for contradiction between nurses and patients especially during the COVID-19 pandemic.Normalized epidemic prevention and control during the preview triage nurse need to all patients to the hospital and the accompanying personnel carries on the preliminary screening.COVID-19 fixed point hospital preview triage nurse with an infected person contact, more prone to anxiety,depression, results in the decrease of efficiency, to treat the service object formulation work sense of fatigue performance, etc.

Objectives

To explore the influencing factors of work burnout of pre-test and triage nurses under normal epidemic prevention and control.

Methods

A total of 110 pre-test and triage nurses from 4 Grade-A hospitals in Shanxi Province were enrolled in this study. The general data questionnaire, Nurse Job Burnout Scale, Pittsburgh Sleep Quality Index Scale, Self-Rating Anxiety Scale and Self-Rating Depression Scale were investigated towork burnout of pre-examination and triage nurses. Comparison between groups using two Independent sample t-test and single factor variance analysis. Multiple regression were applied to analysis factors affecting nurse fatigue feeling dimensions by SPSS22.0. P values<0.05 were considered significant.

Results

As shown in Table 1, different professional title, department, and the sleep quality of preview triage nurses emotional exhaustion dimension comparison(P<0.001), different department nurses to personalized level dimension comparison(P<0.05), nurse personal accomplishment dimension comparison of different cultural levels(P<0.05). Professional title, working department, sleep quality and educational level were the influencing factors of job burnout of pre-test and triage nurses.

Table 1.

Univariate analysis of job burnout of pre-examination triage nurses from different dimensions.

ItemNumberJob BurnoutEmotional exhaustionDepersonalizationPersonal accomplishmentscoreF(t)PscoreF(t)PscoreF(t)Pgender0.0200.8880.1620.6890.3190.575 female10020.10±13.676.98±6.1528.40±13.41 male1021.00±12.088.20±9.5225.98±8.70age(year)5.5110.0074.1430.0210.7500.477 18~253020.33±12.408.40±7.3328.07±6.97 26~304013.60±11.624.00±3.5526.65±10.70 31~404027.00±13.489.20±6.9924.35±8.79marriage-0.9390.352-1.1550.2530.6150.541 unmarried5218.38±13.306.04±6.4027.00±9.99 married5821.79±13.578.03±6.4025.48±8.29job title5.7390.0062.3200.1080.6110.547 junior nurse5216.12±12.945.96±5.9827.26±8.33 senior nurse3819.68±12.536.63±6.1426.50±10.62 supervisor nurse2031.70±10.3810.90±7.2223.40±5.60work experience(year)1.2770.2920.9380.4290.6590.581 ＜12024.80±15.877.60±6.9827.90±5.67 1 ~32418.42±12.056.33±6.5124.25±13.00 4 ~93416.00±10.535.47±6.0324.69±9.16 10 ~203223.06±15.109.06±6.4328.00±7.46department-3.8750.000-2.3370.0230.4010.690 out-patient5413.81±10.505.11±4.3826.70±10.65 emergency5626.32±13.239.00±7.5025.71±7.42average working time per day(hour)0.7910.4591.1250.3322.1730.124 6~6.91815.33±7.925.11±5.2830.56±8.35 7~7.94420.26±13.616.43±7.2827.09±9.33 ≥84822.00±14.888.52±5.8123.61±8.62education degree-0.6430.523-1.0000.3222.4650.017 junior college1816.00±14.764.00±5.4836.50±8.43 college9220.51±13.427.33±6.4725.39±8.70SAS(score)2.0800.0421.6370.1080.4980.621 ≤503417.74±12.716.16±5.3327.12±8.74 >507625.65±13.759.18±8.1625.79±9.31SDS(score)0.2400.8110.8250.4130.4280.671 ≤507219.58±12.946.11±3.9626.58±9.66 >503820.50±13.857.61±7.4025.47±8.05PSQI(score)2.3790.0212.0290.047-0.5210.604 ≤74017.06±12.175.80±4.9826.69±9.33 >77025.65±14.089.35±8.0225.35±8.79

Conclusion

In the COVID-19 epidemic, managers should pay more attention to the main factors that affect the sense of exhaustion of pre-test and triage nurses, and take targeted intervention measures to alleviate the sense of exhaustion of nurses, so as to ensure the safety of nursing.

Acknowledgements

This work was supported by the National Natural Science Foundation of China (No. 82001740).

Disclosure of Interests

None declared

[Validity and reliability of physical activity questionnaires in children and adolescents: a Meta-analysis]

Objective: This review is to systematically summarize the studies examining physical activity questionnaires in children and adolescents and assess the overall validity and reliability, providing evidence on epidemiology research of physical activity in youth. Methods: A meta-analysis was performed using Stata 14.0 software. PubMed/Medline and EMBASE databases using the following terms:'Physical Activity'AND (' Questionnaire'OR'Self-report'OR'Recall') AND'Valid*'AND (' Reliab*'OR'Reproducib*'OR'Sensitiv*'OR'Responsiv*') AND (' Child*' OR'Adolescen*'OR'Youth') were searched from January 2008 to December 2018. Articles meeting the inclusion criteria were screened and adopting 'COnsensusbased Standards for the selection of health status Measurement Instruments' to evaluate the quality of the included studies. Results: This review yielded 17 articles on 20 different physical activity questionnaires, the total number of 2 778 participants for validity study and 2 137 participants for reliability study. The combined values of correlation coefficients in validity study were 0.27 (95%CI: 0.23-0.31) for moderate-to-vigorous intensity physical activity, 0.24 (95%CI: 0.18-0.30) for moderate intensity physical activity, 0.33 (95%CI: 0.24-0.42) for vigorous intensity physical activity. The combined values of intraclass correlation coefficients in reliability study were 0.75 (95%CI: 0.68-0.83) for moderate-to-vigorous intensity physical activity, 0.56 (95%CI: 0.46-0.65) for moderate intensity physical activity, 0.68 (95%CI: 0.61-0.75) for vigorous intensity physical activity. Conclusion: Until now, no questionnaires were identified for good validity and reliability to assess the physical activity level in young population.

[Assessment on the capacity for prevention and control programs for chronic non-communicable diseases in China, in 2014]

Objective: To assess the capacity of prevention and control on chronic non- communicable diseases (NCDs) in China. Methods: On-line questionnaire survey was adopted by 3 395 CDCs at provincial, municipal and county (district) levels and 3 000 primary health care units, and assess on capacity of policy, infrastructure, capacity of training and guidance, cooperation, surveillance, intervention and management, assessment and scientific research from September 2014 to March 2015. Results: (1) Capacity of policy: 23 (71.9%) provincial, 139 (40.6%) municipal and 919 (31.2%) county (district) governments or health administrative departments had existing plans for prevention and control of NCDs. (2) Capacity of infrastructure: 25 (78.1%) provincial, 136 (39.8%) municipal and 529 (18.0%) county (district) CDCs had set up departments dedicated to the prevention and control of NCDs, with 9 787 staff members, accounting for 5.0% of the total CDC personnel, working on NCDs prevention and control programs. 68.1% of the CDCs had special funding set for NCDs prevention and control. (3) Capacity of training and guidance: 2 485 CDCs (74.9%) held all kinds of training on prevention and control of NCDs. 2 571 (87.3%) CDCs at the county (district) level provided technical guidance for primary health care units. (4) Capacity of cooperation: 42.0% of the CDCs had experiences collaborating with the mass media. (5) Capacity of surveillance: 73.8% of the CDCs had set up programs for death registration while less than 50.0% of the CDCs had implemented surveillance programs on major NCDs and related risk factors. In terms of primary health care units, 32.4% of them had set up reporting system for newly developed stroke case and 29.9% of them having programs on myocardial infarction case reporting. (6) Capacity of intervention and management: 69.1% and 68.2% of the CDCs conducted individualized intervention programs on hypertension and diabetes, while less than 40.0% CDCs conducting intervention programs on other NCDs and risk factors. More than 90.0% of the primary health care units carried out follow-up surveys on hypertension and diabetes. However, only 17.4% and 13.7% of the CDCs working on hypertension and diabetes patient management programs while 83.7% and 80.4%, of them following the standardized guidelines for management, with successful rates of control as 59.2% and 55.2%, respectively. (7) Capacity of assessment: 32.4% of the CDCs or health administrations carried out evaluation programs related to the responses on NCDs. (8) Capacity of scientific research: the capacity on scientific research among provincial CDCs was apparently higher than that at the municipal or county (district) CDCs. Conclusions: Compared with the results of previous two surveys, the capacity on policies set for the prevention and control programs improved continuously, at all level NCDs, but remained relatively weak, especially at both county (district) and primary health care units.

[Technical specification for clinical application of critical ultrasonography]

Critical ultrasonography(CUS) is different from the traditional diagnostic ultrasound, the examiner and interpreter of the image are critical care medicine physicians. The core content of CUS is to evaluate the pathophysiological changes of organs and systems and etiology changes. With the idea of critical care medicine as the soul, it can integrate the above information and clinical information, bedside real-time diagnosis and titration treatment, and evaluate the therapeutic effect so as to improve the outcome. CUS is a traditional technique which is applied as a new application method. The consensus of experts on critical ultrasonography in China released in 2016 put forward consensus suggestions on the concept, implementation and application of CUS. It should be further emphasized that the accurate and objective assessment and implementation of CUS requires the standardization of ultrasound image acquisition and the need to establish a CUS procedure. At the same time, the standardized training for CUS accepted by critical care medicine physicians requires the application of technical specifications, and the establishment of technical specifications is the basis for the quality control and continuous improvement of CUS. Chinese Critical Ultrasound Study Group and Critical Hemodynamic Therapy Collabration Group, based on the rich experience of clinical practice in critical care and research, combined with the essence of CUS, to learn the traditional ultrasonic essence, established the clinical application technical specifications of CUS, including in five parts: basic view and relevant indicators to obtain in CUS; basic norms for viscera organ assessment and special assessment; standardized processes and systematic inspection programs; examples of CUS applications; CUS training and the application of qualification certification. The establishment of applied technology standard is helpful for standardized training and clinical correct implementation. It is helpful for clinical evaluation and correct guidance treatment, and is also helpful for quality control and continuous improvement of CUS application.

Abstract P3-03-14: ERα propelled drug-resistance-facilitating global DNA hypermethylation by promoting the DNMT1 gene expression

This abstract was not presented at the symposium.

Protease 2A induces stress granule formation during coxsackievirus B3 and enterovirus 71 infections

Background

Stress granules (SGs) are granular aggregates in the cytoplasm that are formed under a variety of stress situations including viral infection. Previous studies indicate that poliovirus, a member of Picornaviridae, can induce SG formation. However, the exact mechanism by which the picornaviruses induce SG formation is unknown.

Method

The localization of SG markers in cells infected with coxsackievirus B3 (CVB3) or enterovirus 71 (EV71) and in cells expressing each viral protein was determined via immunofluorescence assays or plasmid transfection. Eight plasmids expressing mutants of the 2A protease (2A^pro) of CVB3 were generated using a site-directed mutagenesis strategy. The cleavage efficiencies of eIF4G by CVB3 2A^pro and its mutants were determined via western blotting assays.

Results

In this study, we found that CVB3 infection induced SG formation, as evidenced by the co-localization of some accepted SG markers in viral infection-induced granules. Furthermore, we identified that 2A^pro of CVB3 was the key viral component that triggered SG formation. A 2A^pro mutant with the G122E mutation, which exhibited very low cleavage efficiency toward eIF4G, significantly attenuated its capacity for SG induction, indicating that the protease activity was required for 2A^pro to initiate SG formation. Finally, we observed that SGs also formed in EV71-infected cells. Expression of EV71 2A^pro alone was also sufficient to cause SG formation.

Conclusion

Both CVB3 and EV71 infections can induce SG formation, and 2A^pro plays a crucial role in the induction of SG formation during these infections. This finding may help us to better understand how picornaviruses initiate the SG response.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-014-0192-1) contains supplementary material, which is available to authorized users.

Pyrrolidine dithiocarbamate inhibits enterovirus 71 replication by down-regulating ubiquitin-proteasome system

Enterovirus 71 (EV71) is the main causative pathogen of hand, foot, and mouth disease (HFMD). The severe neurological complications caused by EV71 infection and the lack of effective therapeutic medicine underline the importance of searching for antiviral substances. Pyrrolidine dithiocarbamate (PDTC), an antioxidant, has been reported to inhibit the replication of coxsackievirus B (CVB) through dysregulating ubiquitin-proteasome system (UPS). In this study, we demonstrated that PDTC exerted potent antiviral effect on EV71. Viral RNA synthesis, viral protein expression, and the production of viral progeny were significantly reduced by the treatment of PDTC in Vero cells infected with EV71. Similar to the previous report about the inhibitory effect of PDTC on UPS, we found that PDTC treatment led to decreased levels of polyubiquitinated proteins in EV71-infected cells. The inhibitory effect of PDTC on UPS was further confirmed by the increased accumulation of cell cycle regulatory proteins p21 and p53, which are normally degraded through UPS, while the expression levels of both proteins remained unchanged. We also showed that PDTC had no impact on the activity of proteasome. Thus, we demonstrated that the down-regulation of PDTC on UPS was the result of its inhibition on ubiquitination. More importantly, this study provides evidence that the inhibition on UPS was required for the antiviral activity of PDTC, since MG132, a potent proteasome inhibitor, significantly inhibited the cytopathic effect and viral protein synthesis in EV71-infected cells. We also found that the antioxidant property of PDTC did not contribute to its antiviral effect, since N-acetyl-l-cysteine, a potent antioxidant, could not inhibit viral replication. In addition, CPE and viral protein synthesis were not inhibited in the cells pretreated with PDTC 2h before viral infection and then cultured in the media with no PDTC supplement, while the antioxidant effect of PDTC was retained. PDTC also showed significant inhibition on apoptosis induced by EV71 infection when it was applied at the early stage of viral infection. Our results collectively suggest that PDTC could be a potential anti-EV71 compound which possesses both antiviral and anti-apoptotic capacity.

AUF1 is recruited to the stress granules induced by coxsackievirus B3

Stress granules (SGs) are cytoplasmic granules that are formed in cells when stress occurs. In this study, we found that SGs formed in cells infected with coxsackievirus B3 (CVB3), evidenced with the co-localization of some accepted SG markers in the viral infection-induced granules. We further discovered that adenosine-uridine (AU)-rich element RNA binding factor 1 (AUF1), which can bind to mRNAs and regulate their translation, was recruited to the SGs in response to high dose of CVB3 by detecting the co-localization of AUF1 with SG markers. Similar results were also observed in the enterovirus 71 (EV71)-infected cells. Finally, we demonstrated that AUF1 was also recruited to arsenite-induced SGs, suggesting that the recruitment of AUF1 to SG is not a specific response to viral infection. In summary, our data indicate that both CVB3 and EV71 infections can induce SG formation, and AUF1 is a novel SG component upon the viral infections. Our findings may shed light on understanding the picornavirus-host interaction.

Curcumin inhibits the replication of enterovirus 71 in vitro

Human enterovirus 71 (EV71) is the main causative pathogen of hand, foot, and mouth disease (HFMD) in children. The epidemic of HFMD has been a public health problem in Asia-Pacific region for decades, and no vaccine and effective antiviral medicine are available. Curcumin has been used as a traditional medicine for centuries to treat a diversity of disorders including viral infections. In this study, we demonstrated that curcumin showed potent antiviral effect again EV71. In Vero cells infected with EV71, the addition of curcumin significantly suppressed the synthesis of viral RNA, the expression of viral protein, and the overall production of viral progeny. Similar with the previous reports, curcumin reduced the production of ROS induced by viral infection. However, the antioxidant property of curcumin did not contribute to its antiviral activity, since N-acetyl-l-cysteine, the potent antioxidant failed to suppress viral replication. This study also showed that extracellular signal-regulated kinase (ERK) was activated by either viral infection or curcumin treatment, but the activated ERK did not interfere with the antiviral effect of curcumin, indicating ERK is not involved in the antiviral mechanism of curcumin. Unlike the previous reports that curcumin inhibited protein degradation through ubiquitin–proteasome system (UPS), we found that curcumin had no impact on UPS in control cells. However, curcumin did reduce the activity of proteasomes which was increased by viral infection. In addition, the accumulation of the short-lived proteins, p53 and p21, was increased by the treatment of curcumin in EV71-infected cells. We further probed the antiviral mechanism of curcumin by examining the expression of GBF1 and PI4KB, both of which are required for the formation of viral replication complex. We found that curcumin significantly reduced the level of both proteins. Moreover, the decreased expression of either GBF1 or PI4KB by the application of siRNAs was sufficient to suppress viral replication. We also demonstrated that curcumin showed anti-apoptotic activity at the early stage of viral infection. The results of this study provide solid evidence that curcumin has potent anti-EV71 activity. Whether or not the down-regulated GBF1 and PI4KB by curcumin contribute to its antiviral effect needs further studies.

A 3C(pro)-dependent bioluminescence imaging assay for in vivo evaluation of anti-enterovirus 71 agents

Enterovirus 71 (EV71), a member of Picornaviridae, is one of the major pathogens of human hand, foot and mouth disease. EV71 mainly infects children and causes severe neurological complications and even death. The pathogenesis of EV71 infection is largely unknown, and no clinically approved vaccine or effective treatment is available to date. Here we described a novel bioluminescence imaging approach for EV71 detection. In this approach, a plasmid-based reporter was constructed to express the fusion protein AmN(Q/G)BC, a split firefly luciferase mutant, which can be specifically cleaved by EV71 protease 3C(pro). Upon cleavage, the splitting fusion protein restores luciferase activity. Our test confirmed that AmN(Q/G)BC was specifically cleaved by 3C(pro) and EV71 and restored the luciferase activity to a degree that corresponds to the 3C(pro) and virus doses in cells and mice. The anti-EV71 effect of GW5074 and U0126, two mitogen-activated protein kinase (MAPK) inhibitors, was evaluated using this approach to validate its application of screening anti-EV71 agents. We found that the AmN(Q/G)BC reporter efficiently monitored the inhibitory effect of GW5074 and U0126 on EV71 infection under in vitro and in vivo conditions. The data from AmN(Q/G)BC reporter were consistent with Western blotting and histopathology examination. Taken together, this real-time imaging approach can quantitatively monitor the efficacy of anti-EV71 agents and is valuable for anti-EV71 drug screening and evaluation, especially, under in vivo conditions.

Cytoplasmic redistribution and cleavage of AUF1 during coxsackievirus infection enhance the stability of its viral genome

Coxsackievirus B3 (CVB3) is a causative agent of viral myocarditis, hepatitis, pancreatitis, and meningitis in humans. The adenosine-uridine (AU)-rich element RNA binding factor 1 (AUF1) is an integral component in the regulation of gene expression. AUF1 destabilizes mRNAs and targets them for degradation by binding to AU-rich elements in the 3' untranslated region (UTR) of mRNAs. The 3'-UTR of the CVB3 genome contains canonical AU-rich sequences, raising the possibility that CVB3 RNA may also be subjected to AUF1-mediated degradation. Here, we reported that CVB3 infection led to cytoplasmic redistribution and cleavage of AUF1. These events are independent of CVB3-induced caspase activation but require viral protein production. Overexpression of viral protease 2A reproduced CVB3-induced cytoplasmic redistribution of AUF1, while in vitro cleavage assay revealed that viral protease 3C contributed to AUF1 cleavage. Furthermore, we showed that knockdown of AUF1 facilitated viral RNA, protein, and progeny production, suggesting an antiviral property for AUF1 against CVB3 infection. Finally, an immunoprecipitation study demonstrated the physical interaction between AUF1 and the 3'-UTR of CVB3, potentially targeting CVB3 genome toward degradation. Together, our results suggest that cleavage of AUF1 may be a strategy employed by CVB3 to enhance the stability of its viral genome.

A functional nuclear localization sequence in the VP1 capsid protein of coxsackievirus B3

The capsid proteins of some RNA viruses can translocate to the nucleus and interfere with cellular phenotypes. In this study we found that the VP1 capsid protein of coxsackievirus B3 (CVB3) was dominantly localized in the nucleus of the cells transfected with VP1-expressing plasmid. The VP1 nuclear localization also occurred in the cells infected with CVB3. Truncation analysis indicated that the VP1 nuclear localization sequence located near the C-terminal. The substitution of His220 with threonine completely abolished its translocation. The VP1 proteins of other CVB types might have the nuclear localization potential because this region was highly conserved. Moreover, the VP1 nuclear localization induced cell cycle deregulation, including a prolonged S phase and shortened G2-M phase. Besides these findings, we also found a domain between Ala72 and Phe106 that caused the VP1 truncates dotted distributed in the cytoplasm. Our results suggest a new pathogenic mechanism of CVB.

Gemcitabine in combination with intraperitoneal cisplatin in advanced hepatobiliary cancers

e15666

Background: Standard chemotherapy for advanced hepatobiliary cancers remains undefined. This study was to observe the therapeutic effect of gemcitabine combined with intraperitoneal cisplatin for the treatment of advanced hepatobiliary cancers and analyze their toxicities. Methods: Patients with measurable hepatobiliary cancers were unrandomized into gemcitabine (GEM) + cisplatin (DDP) (GEM group) and epirubicin (EPI) + DDP (EPI group). GEM was used intravenously by infusion for 30 min with the dose to 1,000 mg/m2 on day 1 and 8; cisplatin was infused intraperitoneal with a dose of 25mg/m2 on day1, 3 and 5. Twenty-one days counted as one cycle. After 2 cycles, treatment efficacy and adverse events were evaluated according to WHO criteria. Results: A total of 76 patients were enrolled from May 2004 to May 2006, with 30 patients for EPI group and 46 patients for GEM group, and all the patients were eligible for effectiveness analysis. Among GEM group patients, there was no complete response. The partial response rate was 32.61% and clinical benefit response (CR+ PR +SD) was 67.39%. All those data mentioned above were significantly higher than that of EPI group. The main adverse re-ction was hematologic toxicity, while nonhematologic toxicity was mild. Conclusions: This study demonstrated that combination gemcitabine with intraperitoneal infusion of cisplatin was an effective and safety treatment for the patients with advanced hepatobiliary cancers.

No significant financial relationships to disclose.

ERK MAP kinase-activated Arf6 trafficking directs coxsackievirus type B3 into an unproductive compartment during virus host-cell entry

Clathrin- and caveolae-mediated endocytosis have been implicated in the productive entry of many viruses into host cells. ADP-ribosylation factor 6 (Arf6)-dependent endocytosis is another endocytosis pathway that traffics from the cell surface and it is the only Arf that traffics at the plasma membrane. However, little is known about Arf6-dependent trafficking during virus entry. This study showed that coxsackievirus type B3 (CVB3) associated with decay-accelerating factor in non-polarized HeLa cells can be redirected into non-productive compartments by Arf6-dependent internalization, thus restricting infection. Overexpression of wild-type (WT) and constitutively active (CA) Arf6 in HeLa cells resulted in a 2.3- and 3.6-fold decrease in infection, respectively. A dominant-negative inhibitor of Arf6 recovered restriction of infection by WT-Arf6 and CA-Arf6. RNA interference of endogenous Arf6 resulted in a 3.3-fold increase in CVB3 titre in HeLa cells. It was shown that coxsackie-adenovirus receptor (CAR) ligation by virus or CAR-specific antibody could activate extracellular signal-regulated kinase (ERK) of the mitogen-activated protein kinase family and lead to Arf6-mediated viral restriction. In the absence of ERK activation, CVB3 internalization into early endosomes was inhibited and subsequent infection was reduced, but Arf6-mediated restriction was also abolished. In conclusion, receptor-mediated signalling enhances CVB3 entry whilst also activating non-productive pathways of virus entry; thus, virus infection is an equilibrium of productive and non-productive pathways of entry.

Autophagosome supports coxsackievirus B3 replication in host cells

Recent studies suggest a possible takeover of host antimicrobial autophagy machinery by positive-stranded RNA viruses to facilitate their own replication. In the present study, we investigated the role of autophagy in coxsackievirus replication. Coxsackievirus B3 (CVB3), a picornavirus associated with viral myocarditis, causes pronounced intracellular membrane reorganization after infection. We demonstrate that CVB3 infection induces an increased number of double-membrane vesicles, accompanied by an increase of the LC3-II/LC3-I ratio and an accumulation of punctate GFP-LC3-expressing cells, two hallmarks of cellular autophagosome formation. However, protein expression analysis of p62, a marker for autophagy-mediated protein degradation, showed no apparent changes after CVB3 infection. These results suggest that CVB3 infection triggers autophagosome formation without promoting protein degradation by the lysosome. We further examined the role of the autophagosome in CVB3 replication. We demonstrated that inhibition of autophagosome formation by 3-methyladenine or small interfering RNAs targeting the genes critical for autophagosome formation (ATG7, Beclin-1, and VPS34 genes) significantly reduced viral replication. Conversely, induction of autophagy by rapamycin or nutrient deprivation resulted in increased viral replication. Finally, we examined the role of autophagosome-lysosome fusion in viral replication. We showed that blockage of the fusion by gene silencing of the lysosomal protein LAMP2 significantly promoted viral replication. Taken together, our results suggest that the host's autophagy machinery is activated during CVB3 infection to enhance the efficiency of viral replication.

Ubiquitination is required for effective replication of coxsackievirus B3

BACKGROUND

Protein ubiquitination and/or degradation by the ubiquitin/proteasome system (UPS) have been recognized as critical mechanisms in the regulation of numerous essential cellular functions. The importance of the UPS in viral pathogenesis has become increasingly apparent. Using murine cardiomyocytes, we have previously demonstrated that the UPS plays a key role in the replication of coxsackievirus B3 (CVB3), an important human pathogen associated with various diseases. To further elucidate the underlying mechanisms, we examined the interplay between the UPS and CVB3, focusing on the role of ubiquitination in viral lifecycle.

METHODOLOGY/PRINCIPAL FINDINGS

As assessed by in situ hybridization, Western blot, and plaque assay, we showed that proteasome inhibition decreased CVB3 RNA replication, protein synthesis, and viral titers in HeLa cells. There were no apparent changes in 20S proteasome activities following CVB3 infection. However, we found viral infection led to an accumulation of protein-ubiquitin conjugates, accompanied by a decreased protein expression of free ubiquitin, implicating an important role of ubiquitination in the UPS-mediated viral replication. Using small-interfering RNA, we demonstrated that gene-silencing of ubiquitin significantly reduced viral titers, possibly through downregulation of protein ubiquitination and subsequent alteration of protein function and/or degradation. Inhibition of deubiquitinating enzymes apparently enhances the inhibitory effects of proteasome inhibitors on CVB3 replication. Finally, by immunoprecipitation, we showed that coxsackieviral polymerase 3D was post-translationally modified by ubiquitination and such modification might be a prerequisite for its function in transcriptional regulation of viral genome.

CONCLUSION

Coxsackievirus infection promotes protein ubiquitination, contributing to effective viral replication, probably through ubiquitin modification of viral polymerase.

Proteasome inhibition attenuates coxsackievirus-induced myocardial damage in mice

Coxsackievirus B3 (CVB3) is one of the most prevalent pathogens of viral myocarditis, which may persist chronically and progress to dilated cardiomyopathy. We previously demonstrated a critical role of the ubiquitin-proteasome system (UPS) in the regulation of coxsackievirus replication in mouse cardiomyocytes. In the present study, we extend our interest to an in vivo animal model to examine the regulation and role of the UPS in CVB3-induced murine myocarditis. Male myocarditis-susceptible A/J mice at age 4-5 wk were randomized to four groups: sham infection + vehicle (n = 10), sham infection + proteasome inhibitor (n = 10), virus + vehicle (n = 20), and virus + proteasome inhibitor (n = 20). Proteasome inhibitor was administered subcutaneously once a day for 3 days. Mice were killed on day 9 after infection, and infected hearts were harvested for Western blot analysis, plaque assay, immunostaining, and histological examination. We showed that CVB3 infection led to an accumulation of ubiquitin conjugates at 9 days after infection. Protein levels of ubiquitin-activating enzyme E1A/E1B, ubiquitin-conjugating enzyme UBCH7, as well as deubiquitinating enzyme UCHL1 were markedly increased in CVB3-infected mice compared with sham infection. However, there was no significant alteration in proteasome activities at 9 days after infection. Immunohistochemical staining revealed that increased expression of E1A/E1B was mainly localized to virus-damaged cells. Finally, we showed that application of a proteasome inhibitor significantly reduced CVB3-induced myocardial damage. This observation reveals a novel mechanism of coxsackieviral pathogenesis, and suggests that the UPS may be an attractive therapeutic target against coxsackievirus-induced myocarditis.

The impact of CVB3 infection on host cell biology

CVB3 myocarditis can lead to dilated cardiomyopath (DCM). DCM is one of the leading causes of the need for heart transplantation, so it is important to understand the life cycle of CVB3 and its interactions with the host cell. Infection causes rapid death of host cardiomyocytes by altering normal cellular homeostasis for the efficient release of progeny virion. In this chapter, we will examine the impact that CVB3 replication has on host cell biology, from events that take place at receptor ligation to progeny virus release. The primary focus will be on the myriad of signalling pathways that are activated at all stages of virus replication and their downstream effects. We will also discuss some of the extracellular effects of infection as well as immune and matrixmetalloprotease activation. Interactions of host cell proteins with the 5' untranslated region (UTR) are required for translation and replication of CVB3. These interactions do not always benefit the virus since the interactions of a 28-kDa host protein with the 5' UTR are thought to be responsible for inhibitory activity against CVB3. Finally, we will discuss how the elucidation of the different stages of replication has provided the opportunity to develop novel strategies for combating CVB3 infection.

Coxsackievirus B3 activates nuclear factor kappa B transcription factor via a phosphatidylinositol-3 kinase/protein kinase B-dependent pathway to improve host cell viability

Coxsackievirus B3 (CVB3) is the most common viral infectant of heart muscle. CVB3 directly injures cardiomyocytes. We have previously reported on a regulatory role for the phosphatidylinositol-3 kinase (PI3K)/protein kinase B (Akt) pathway during CVB3 infection. Yet, the mechanism underlying this regulatory role has not been elucidated. The PI3K/Akt pathway is involved in various cellular processes and exerts its function through the activation of several downstream effectors. Among them, nuclear factor kappa B (NFkappaB) transcription factor is involved in inflammation, survival and apoptosis. In this study, we investigated the role of NFkappaB as a potential downstream mediator of signals through the PI3K/Akt cascade, in regulating CVB3-induced cellular injury. We report that CVB3 infection induces the translocation of NFkappaB into the nucleus of infected cells. Inhibition of the PI3K/Akt pathway markedly decreases virus-induced NFkappaB activation. Further, NFkappaB inhibition significantly suppresses host viability, suggesting a pro-survival role for NFkappaB. Short-term treatment of cells with tumour necrosis factor-alpha (TNF-alpha), a potent activator of NFkappaB, promotes host cell viability without affecting virus replication. However, a prolonged treatment has a detrimental effect on cells, indicating the existence of a delicate balance between the anti- and pro-apoptotic roles of TNF-alpha in the setting of CVB3 infection.

Inhibition of the extracellular signal-regulated kinase signaling pathway is correlated with proteasome inhibitor suppression of coxsackievirus replication

The ubiquitin/proteasome system (UPS), a major intracellular protein degradation pathway, plays a critical role in coxsackieviral replication. To elucidate the mechanisms by which the UPS regulates viral replication, we studied the influence of proteasome inhibition on signaling through the extracellular signal-regulated kinase (ERK) pathway, a pathway which has been previously demonstrated to be necessary for coxsackieviral replication and contribute to virus-mediated pathogenesis. We found that proteasome inhibition reduced coxsackievirus-induced ERK phosphorylation in a dose-dependent manner, which is correlated with an induction of the mitogen-activated protein kinase phosphatase-1 (MKP-1). Blockade of MKP induction by short-interfering RNA attenuated the loss of ERK phosphorylation, and subsequently restored viral replication. Our results suggest that inhibition of the ERK signaling pathway contributes, as least in part, to proteasome inhibitor-mediated reduction of coxsackievirus replication, demonstrating a converging function of major intracellular signaling and protein degradation pathways in the regulation of viral replication.

Apoptosis repressor with caspase recruitment domain (ARC) inhibits myogenic differentiation

Apoptosis repressor with caspase recruitment domain (ARC), an anti-apoptotic protein, is highly expressed in differentiated heart and skeletal muscle. Apoptosis and differentiation share numerous common pathways; therefore, we examined the impact of ARC on H9c2-myoblast differentiation. We demonstrate that ARC expression levels increase and stabilize upon differentiation. ARC-overexpression in pre-differentiated H9c2-cells suppresses differentiation; indicated by increased myotube formation, nuclear fusion and expression of the differentiation markers myogenin and troponin-T. ARC-overexpression inhibited myoblast differentiation associated caspase-3 activation, suggesting ARC inhibits myogenic differentiation through caspase inhibition. In summary, we show a novel role for ARC in the regulation of muscle differentiation.

Dysregulation of the ubiquitin-proteasome system by curcumin suppresses coxsackievirus B3 replication

Curcumin (diferuloylmethane), a natural polyphenolic compound extracted from the spice turmeric, has been reported to have anti-inflammatory, antioxidant, and antiproliferative properties by modulating multiple cellular machineries. It inhibits several intracellular signaling pathways, including the mitogen-activated protein kinases (MAPKs), casein kinase II (CKII), and the COP9 signalosome (CSN), in various cell types. It has also been recently demonstrated that exposure to curcumin leads to the dysregulation of the ubiquitin-proteasome system (UPS). Coxsackievirus infection is associated with various diseases, including myocarditis and dilated cardiomyopathy. In searching for new antiviral agents against coxsackievirus, we found that treatment with curcumin significantly reduced viral RNA expression, protein synthesis, and virus titer and protected cells from virus-induced cytopathic effect and apoptosis. We further demonstrated that reduction of viral infection by curcumin was unlikely due to inhibition of CVB3 binding to its receptors or CVB3-induced activation of MAPKs. Moreover, gene silencing of CKII and Jab1, a component of CSN, by small interfering RNAs did not inhibit the replication of coxsackievirus, suggesting that the antiviral action of curcumin is independent of these pathways. Finally, we showed that curcumin treatment reduced both the 20S proteasome proteolytic activities and the cellular deubiquitinating activities, leading to increased accumulation of ubiquitinated proteins and decreased protein levels of free ubiquitin. We have recently demonstrated that the UPS-mediated protein degradation and/or modification plays a critical role in the regulation of coxsackievirus replication. Thus, our results suggest an important antiviral effect of curcumin wherein it potently inhibits coxsackievirus replication through dysregulation of the UPS.

Novel role for integrin-linked kinase in modulation of coxsackievirus B3 replication and virus-induced cardiomyocyte injury

Viral myocarditis is a major cause of sudden cardiac death in children and young adults. Among viruses, coxsackievirus B3 (CVB3) is the most common agent for myocarditis. Recently, more consideration has been given to the role of signaling pathways in pathogenesis of enteroviral myocarditis, providing new platform for identifying a new potential therapeutic target for this, so far, incurable disease. Previously, we reported on the role of the protein kinase-B/Akt in CVB3 replication and virus-induced cell injury. Here, we report on regulation of virus-induced Akt activation by the integrin-linked kinase in infected mouse cardiomyocytes and HeLa cells. This study also presents the first observation that inhibition of ILK in CVB3-infected cells significantly improves the viability of infected cells, while blocking viral replication and virus release. Complementary experiments using a constitutively active form of Akt1 revealed that the observed protective effect of ILK inhibition is dependent on the associated downregulation of virus-induced Akt activation. To our knowledge, this is the first report of such beneficial effects of ILK inhibition in a viral infection model and conveys new insights in our efforts to characterize a novel therapeutic target for treatment of enteroviral myocarditis.

Stress-activated protein kinases are involved in coxsackievirus B3 viral progeny release

Stress-activated protein kinases (SAPKs), consisting of c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38 MAPK), are activated upon various environmental stimuli, including viral infections. Cellular survival and death signaling events following coxsackievirus B3 (CVB3) infection have been studied in relationship to viral replication, but the role of SAPKs has not been scrutinized. In this study, we found that the phosphorylation of JNK1/2 and p38 MAPK was increased during active replication of CVB3 and that their phosphorylation was independent of CVB3-induced caspase activation or production of reactive oxygen species. The roles of these kinases in CVB3 infection were further evaluated using specific inhibitors: SP600125 for JNK1/2 and SB203580 for p38 MAPK. JNK1/2 inhibitors reduced CVB3-induced phosphorylation of activating transcription factor 2, and the p38 MAPK inhibitor reduced CVB3-induced phosphorylation of heat shock protein 27. Although inhibition of these kinases by specific inhibitors did not affect CVB3 viral protein synthesis, inhibition of p38 MAPK but not of JNK1/2 resulted in significant reduction of viral progeny release, suppression of CVB3-induced cell death, and blockage of CVB3-induced caspase-3 activation in infected cells. We conclude that SAPK pathways play critical roles in the life cycle of CVB3, particularly in viral progeny release.

Liposome-mediated transient transfection reduces cholesterol-dependent coxsackievirus infectivity

Liposome-mediated gene delivery provides a powerful strategy for the study of gene function and for gene therapy. Coxsackievirus B3 is an important human pathogen associated with various diseases. Here we reported that liposome-mediated transient transfection of plasmid cDNA inhibited coxsackieviral replication at the levels of RNA, protein and viral progeny release. These inhibitory effects were observed in various cell types and by using different liposome reagents. We further showed that the inhibition was likely due to the lack of virus attachment. Moreover, we showed that addition of cholesterol restored, at least in part, the viral infectivity. Interestingly, we found that membrane cholesterol levels were unchanged during transfection, indicating that disruption rather than depletion of membrane cholesterol contributes to the inhibitory effects of transfection. Our data suggest that liposome-mediated cDNA transient transfection inhibits coxsackievirus infectivity via inhibition of viral attachment, which is likely occurring through the changes of membrane cholesterol integrity.

Inhibition of glycogen synthase kinase 3beta suppresses coxsackievirus-induced cytopathic effect and apoptosis via stabilization of beta-catenin

Coxsackievirus B3 (CVB3), a common human pathogen for viral myocarditis, induces a direct cytopathic effect (CPE) and apoptosis on infected cells. To elucidate the mechanisms that contribute to these processes, we studied the role of glycogen synthase kinase 3beta (GSK3beta). GSK3beta activity was significantly increased after CVB3 infection and addition of tyrosine kinase inhibitors blocked CVB3-triggered GSK3beta activation. Inhibition of caspase activity had no inhibitory effect on CVB3-induced CPE; however, blockage of GSK3beta activation attenuated both CVB3-induced CPE and apoptosis. We further showed that CVB3 infection resulted in reduced beta-catenin protein expression, and GSK3beta inhibition led to the accumulation and nuclear translocation of beta-catenin. Finally, we found that CVB3-induced CPE and apoptosis were significantly reduced in cells stably overexpressing beta-catenin. Taken together, our results demonstrate that CVB3 infection stimulates GSK3beta activity via a tyrosine kinase-dependent mechanism, which contributes to CVB3-induced CPE and apoptosis through dysregulation of beta-catenin.

Pyrrolidine dithiocarbamate reduces coxsackievirus B3 replication through inhibition of the ubiquitin-proteasome pathway

Coxsackievirus B3 (CVB3) is one of the most common pathogens for viral myocarditis. The lack of effective therapeutics for CVB3-caused viral diseases underscores the importance of searching for antiviral compounds. Pyrrolidine dithiocarbamate (PDTC) is an antioxidant and is recently reported to inhibit ubiquitin-proteasome-mediated proteolysis. Previous studies have shown that PDTC inhibits replication of rhinovirus, influenza virus, and poliovirus. In the present study, we report that PDTC is a potent inhibitor of CVB3. Coxsackievirus-infected HeLa cells treated with PDTC showed a significant reduction of CVB3 viral RNA synthesis, viral protein VP1 expression, and viral progeny release. Similar to previous observation that divalent ions mediate the function of PDTC, we further report that serum-containing copper and zinc are required for its antiviral activity. CVB3 infection resulted in massive generation of reactive oxygen species (ROS). Although PDTC alleviated ROS generation, the antiviral activity was unlikely dependent on its antioxidant effect because the potent antioxidant, N-acetyl-L-cysteine, failed to inhibit CVB3 replication. Consistent with previous reports that PDTC inhibits ubiquitin-proteasome-mediated protein degradation, we found that PDTC treatment led to the accumulation of several short-lived proteins in infected cells. We further provide evidence that the inhibitory effect of PDTC on protein degradation was not due to inhibition of proteasome activity but likely modulation of ubiquitination. Together with our previous findings that proteasome inhibition reduces CVB3 replication (H. Luo, J. Zhang, C. Cheung, A. Suarez, B. M. McManus, and D. Yang, Am. J. Pathol. 163:381-385, 2003), results in this study suggest a strong antiviral effect of PDTC on coxsackievirus, likely through inhibition of the ubiquitin-proteasome pathway.

Detection of cardiac signaling in the injured and hypertrophied heart

Cardiac hypertrophy is a compensatory response to a variety of physiological or pathological stimuli. However, prolonged hypertrophic responses may eventually lead to heart failure, arrhythmia, and sudden death. A number of intracellular signaling pathways have been implicated to play a critical role in the regulation of cardiac hypertrophy. In this chapter, the mitogen-activated protein kinase signaling pathway is used to illustrate conventional assays to detect the expression, phosphorylation, and activation of signaling proteins during cardiac hypertrophy, including Western blot, immunohistochemical staining, and immune complex kinase assays. Newly emerging techniques for analyzing cell signaling are also discussed in this chapter. Identifying and characterizing the expression and activation of these signaling proteins will provide important insights into the mechanisms that regulate hypertrophic cell growth and assist in development of new therapeutic approaches to limit cardiac hypertrophy.

Regulation of the versican promoter by the beta-catenin-T-cell factor complex in vascular smooth muscle cells

The proteoglycan versican is pro-atherogenic and central to vascular injury and repair events. We identified the signaling pathways and promoter elements involved in regulation of versican expression in vascular smooth muscle cells. Phosphatidylinositol 3-kinase inhibitor, LY294002, significantly decreased versican-luciferase (Luc) promoter activity and endogenous mRNA levels. We further examined the roles of protein kinase B and glycogen synthase kinase (GSK)-3beta, downstream effectors of phosphatidylinositol 3-kinase, in the regulation of versican transcription. Co-transfection of dominant negative and constitutively active protein kinase B constructs with a versican-Luc construct decreased and increased promoter activity, respectively. Inhibition of GSK-3beta activity by LiCl augmented accumulation of beta-catenin and caused induction of versican-Luc activity as well as versican mRNA levels. Beta-catenin has no DNA binding domain, therefore it cannot directly induce transcription of the versican promoter. Software analysis of the versican promoter revealed two potential binding sites for T-cell factors (TCFs), proteins that confer transcriptional activation of beta-catenin. Electrophoretic mobility shift and supershift assays revealed specific binding of human TCF-4 and beta-catenin to oligonucleotides corresponding to a potential TCF binding site in the versican promoter. In addition to binding assays, we directly assessed the dependence of versican promoter activity on TCF binding sites. Site-directed mutagenesis of the TCF site located -492 bp relative to the transcription start site markedly diminished versican-Luc activity. Co-transfection of TCF-4 with versican-Luc did not increase promoter activity, but addition of beta-catenin and TCF-4 significantly stimulated basal versican promoter activity. Our findings suggest that versican transcription is predominantly mediated by the GSK-3beta pathway via the beta-catenin-TCF transcription factor complex in smooth muscle cells, wherein such regulation contributes to the normal or aberrant formation of provisional matrix in vascular injury and repair events.

PTP alpha regulates integrin-stimulated FAK autophosphorylation and cytoskeletal rearrangement in cell spreading and migration

We investigated the molecular and cellular actions of receptor protein tyrosine phosphatase (PTP) alpha in integrin signaling using immortalized fibroblasts derived from wild-type and PTP alpha-deficient mouse embryos. Defects in PTP alpha-/- migration in a wound healing assay were associated with altered cell shape and focal adhesion kinase (FAK) phosphorylation. The reduced haptotaxis to fibronectin (FN) of PTP alpha-/- cells was increased by expression of active (but not inactive) PTP alpha. Integrin-mediated formation of src-FAK and fyn-FAK complexes was reduced or abolished in PTP alpha-/- cells on FN, concomitant with markedly reduced phosphorylation of FAK at Tyr397. Reintroduction of active (but not inactive) PTP alpha restored FAK Tyr-397 phosphorylation. FN-induced cytoskeletal rearrangement was retarded in PTP alpha-/- cells, with delayed filamentous actin stress fiber assembly and focal adhesion formation. This mimicked the effects of treating wild-type fibroblasts with the src family protein tyrosine kinase (Src-PTK) inhibitor PP2. These results, together with the reduced src/fyn tyrosine kinase activity in PTP alpha-/- fibroblasts (Ponniah et al., 1999; Su et al., 1999), suggest that PTP alpha functions in integrin signaling and cell migration as an Src-PTK activator. Our paper establishes that PTP alpha is required for early integrin-proximal events, acting upstream of FAK to affect the timely and efficient phosphorylation of FAK Tyr-397.

Interaction of farnesylated PRL-2, a protein-tyrosine phosphatase, with the beta-subunit of geranylgeranyltransferase II

Protein of regenerating liver (PRL)-1, -2, and -3 comprise a subgroup of closely related protein-tyrosine phosphatases featuring a C-terminal prenylation motif conforming to either the consensus sequence for farnesylation, CAAX, or geranylgeranylation, CCXX. Yeast two-hybrid screening for PRL-2-interacting proteins identified the beta-subunit of Rab geranylgeranyltransferase II (betaGGT II). The specific interaction of betaGGT II with PRL-2 but not with PRL-1 or -3 occurred in yeast and HeLa cells. Chimeric PRL-1/-2 molecules were tested for their interaction with betaGGT II, and revealed that the C-terminal region of PRL-2 is required for interaction, possibly the PRL variable region immediately preceeding the CAAX box. Additionally, PRL-2 prenylation is prequisite for betaGGT II binding. As prenylated PRL-2 is localized to the early endosome, we propose that this is where the interaction occurs. PRL-2 is not a substrate for betaGGT II, as isoprenoid analysis showed that PRL-2 was solely farnesylated in vivo. Co-expression of the alpha-subunit (alpha) of GGT II, betaGGT II, and PRL-2 resulted in alpha/betaGGT II heterodimer formation and prevented PRL-2 binding. Expression of PRL-2 alone inhibited the endogenous alpha/betaGGT II activity in HeLa cells. Together, these results indicate that the binding of alphaGGT II and PRL-2 to betaGGT II is mutually exclusive, and suggest that PRL-2 may function as a regulator of GGT II activity.

Expression and significance of cell cycle-related proteins Cyclin Dl, CDK4, p27, E2F-l and Ets-1 in chondrosarcoma of the jaws

To elucidate the expression and significance of cell cycle-associated proteins in chondrosarcoma of the jaws, Cyclin Dl, CDK4, p27, E2F-l and Ets-l expressions were examined in chondrosarcoma and osteochondroma of the jaws by immunohistochemical ABC method. The results demonstrated that Cyclin Dl, CDK4, p27, E2F-1 and Ets-1 were positive 75% (15 of 20), 60% (12 of 20), 25% (5 of 20), 65% (13 of 20) and 60% (12 of 20) in chondrosarcoma of the jaws, respectively. There was no remarkable difference in the expression of these proteins among histological grades of the chondrosarcoma (P>0.05). In osteochondroma of the jaws, CDK4 and E2F with an equal positivity of 12.5% (1 of 8), whereas p27 was positive 75% (6 of 8). None of the osteochondroma cases was immunohistochemically positive for Cycin Dl and Ets-1. In addition, the positive rate of Cyclin Dl, CDK4, E2F-l and Ets-1 proteins was significantly higher, whereas p27 was lower in chondrosarcoma than in osteochondroma of the jaws (P<0.05). These data show that the expression of cell cycle regulatory proteins is altered in chondrosarcoma of the jaws: cyclin Dl, CDK4, E2F-1 and Ets-1 are over-expressed and p27 is low-expressed.

[The ultrastructure of bone morphogenetic protein 2 gene transfected human periodontal ligament fibroblasts]

OBJECTIVE

To observe the ultrastructure of bone morphogenetic protein 2 (BMP-2) gene transfected human periodontal ligament fibroblasts (HPDLFs).

METHODS

An expression vector for BMP-2 was transfected into HPDLFs by using Lipofect AMINE. The stable expression of BMP-2 was determined by in situ hybridization and immunohistochemistry. The ultrastructure of the transfected cells was examined by transmission electron microscope.

RESULTS

The results showed that the BMP-2 gene transfected cells showed expansive endoplasmic reticulum, incremental myelin sheath-like figures and matrix vesicles. The collagenous fibrillae was distributed widely intercellular.

CONCLUSIONS

The results suggests that BMP-2 gene transfection tends to accelerate HPDLFs into osteoblast-like cells.

[The biological effects of transforming growth factor-beta on human periodontal ligament fibroblasts]

OBJECTIVE

To evaluate the biological effects of transforming growth factor-beta (TGF-beta) on human periodontal ligament fibroblasts (HPDLFs).

METHODS

HPDLFs were primary cultured and examined for the effects of TGF-beta on its proliferation, alkaline phosphatase (ALP) activity, osteocalcin (OC) synthesis and formation of the mineralized nodules.

RESULTS

TGF-beta(0.0050-0.1000 mg/L) significantly stimulated the proliferation of HPDLFs. The ALP activity of HPDLFs was elevated evidently by 0.0050 mg/L TGF-beta. TGF-beta (0.0005-0.1000 mg/L) had no effects on OC synthesis and formation of the mineralized nodules of HPDLFs.

CONCLUSIONS

The effects of TGF-beta on HPDLFs are dose-dependent. TGF-beta can stimulate HPDLFs to express some of osteoblastic phenotype, and it lacks the abilility to promote maturation of the osteogenic phenotype.

Prenylation-dependent association of protein-tyrosine phosphatases PRL-1, -2, and -3 with the plasma membrane and the early endosome

PRL-1, -2, and -3 represent a novel class of protein-tyrosine phosphatase with a C-terminal prenylation motif. Although PRL-1 has been suggested to be associated with the nucleus, the presence of three highly homologous members and the existence of a prenylation motif call for a more detailed examination of their subcellular localization. In the present study, we first demonstrate that mouse PRL-1, -2, and -3 are indeed prenylated. Examination of N-terminal epitope-tagged PRL-1, -2, and -3 expressed in transiently transfected cells suggests that PRL-1, -2, and -3 are present on the plasma membrane and intracellular punctate structures. Stable Chinese hamster ovary cells expressing PRL-1 and -3 in an inducible manner were established. When cells were treated with brefeldin A, PRL-1 and -3 accumulated in a collapsed compact structure around the microtubule-organizing center. Furthermore, PRL-1 and -3 redistributed into swollen vacuole-like structures when cells were treated with wortmannin. These characteristics of PRL-1 and -3 are typical for endosomal proteins. Electron microscope immunogold labeling reveals that PRL-1 and -3 are indeed associated with the plasma membrane and the early endosomal compartment. Expression of PRL-3 is detected in the epithelial cells of the small intestine, where PRL-3 is present in punctate structures in the cytoplasm. When cells are treated with FTI-277, a selective farnesyltransferase inhibitor, PRL-1, -2, and -3 shifted into the nucleus. Furthermore, a mutant form of PRL-2 lacking the C-terminal prenylation signal is associated with the nucleus. These results establish that the primary association of PRL-1, -2, and -3 with the membrane of the cell surface and the early endosome is dependent on their prenylation and that nuclear localization of these proteins may be triggered by a regulatory event that inhibits their prenylation.

[Effects of TGF beta on BMP-2 gene transfection cells in vitro]

OBJECTIVE

To elucidate the mechanism of bone morphogenetic protein-2(BMP-2) and transforming growth factor beta(TGF beta) on cell differentiation.

METHODS

A phagemid expression vector for human BMP-2 (pBK-B2) was constructed and transfected into the NIH3T3 cells by using lipofectamine. Positive cell clones were selected with G418. The stable transfection and expression of BMP-2 were determined by using in situ hybridization and immunohistochemistry methods. The proliferativity of the transfected cells treated with TGF beta were assayed by MTT method. Alkaline phosphatase (ALP) and osteocalcin (OC) production were also measured.

RESULTS

The proliferation of the transfected cells was stimulated after being treated with TGF beta (50 ng/ml). But the ALP activity and OC production were inhibited.

CONCLUSION

The effects of TGF beta are closely related to many factors, and BMP and TGF beta may be synergistic in cell proliferation and differentiation.

Bezafibrate, an anti-hypertriglyceridemic drug, attenuates vascular hyperresponsiveness and elevated blood pressure in fructose-induced hypertensive rats

A high fructose diet induces hypertension, hyperinsulinemia - insulin resistance, and hypertriglyceridemia (syndrome X). In this study, we investigated the role of an abnormal lipid profile in mediating fructose-induced hypertension. We hypothesized that bezafibrate, a lipid-lowering drug, would reduce elevated blood pressure and inhibit increased vascular reactivity in fructose-fed rats. Male rats were placed on four different diets: group 1 was fed standard chow (n = 6); group 2 was fed 60% fructose (n = 5); group 3 was fed fructose plus bezafibrate (30 mg x kg(-1) x day(-1); drinking water; n = 5); and group 4 was fed standard chow plus bezafibrate (n = 6). In addition, the direct effects of very low density lipoprotein (VLDL) on vascular reactivity were examined. Bezafibrate treatment lowered blood pressure, free fatty acids, and triglycerides in the fructose-fed group, suggesting that lipid abnormalities play a role in the elevation of blood pressure in the fructose-induced hypertensive rat. Aortae from fructose-fed rats were hyperresponsive to the calcium channel agonist Bay K 8644, which was normalized with bezafibrate treatment. Incubation of aortae in a VLDL medium resulted in increased responsiveness to Bay K 8644, lending further support to lipid abnormalities altering vascular reactivity. An altered lipid profile evidenced by elevated triglycerides and free fatty acids is causally related to the development of high blood pressure and increased vascular reactivity in the fructose-induced hypertensive rat.

Effect of amiloride analogs on DOCA-salt-induced hypertension in rats

Intracerebroventricular infusions of an amiloride analog, benzamil, reduce blood pressure in several rat models of hypertension. This effect has been attributed to an inhibition of amiloride-sensitive Na+ channels in the brain. This study examines whether intracerebroventricular benzamil would prevent the onset of deoxycorticosterone acetate (DOCA)-salt-induced hypertension in rats and whether this effect correlates with an inhibition of ion transport through the known amiloride-sensitive cation channels at the blood-brain barrier. We also examine whether the effects of benzamil on blood pressure are mediated by a Na+ channel by comparing the effects of different amiloride analogs. Benzamil (0.15 and 0.5 microgram/h icv) did significantly attenuate the increase in blood pressure induced by DOCA treatment. This antihypertensive effect, however, was not associated with an alteration in a blood-brain barrier ion transport as assessed by measurements of blood-to-brain 22Na transport and cerebral spinal fluid Na+ and K+ concentrations. Indeed, intracerebroventricular infusion of dimethyl amiloride, an amiloride analog with low affinity for Na+ channels, also attenuated the increase in blood pressure induced by DOCA-salt treatment. Comparisons of the effects of benzamil, dimethyl amiloride, and 3,4-dichlorobenzamil, another amiloride analog, suggest that these antihypertensive effects are mediated by an inhibition of Na+/Ca2+ exchange in the brain.

Endothelium dependent and independent relaxations induced by ceramide in vascular smooth muscles

The second messenger of sphingomyelin signaling, ceramide, acts as an intracellular signal via phosphatase activation and protein kinase C (PKC) inhibition. We tested the hypothesis that ceramide may have an regulatory role in determining vascular tone. Natural ceramide was applied to phenylephrine precontracted aortic rings from Sprague-Dawley rats in an organ bath. In endothelium-intact aortic rings, concentrations of ceramide at 10(-6) and 10(-5) mole/L induced 24 +/- 6 and 52 +/- 7% relaxation, respectively. Removal of the endothelium significantly inhibited ceramide-induced relaxation to 13 +/- 5% (10(-6) mole/L) and 29 +/- 5% (10(-5) mole/L). Similar inhibition was observed in endothelium-intact aortic rings pretreated with N omega-nitro-L-arginine (10(-4) mole/L) or methylene blue (10(-5) mole/L), suggesting that endothelium-derived nitric oxide is involved in ceramide-induced relaxation. N-acetylsphingosine (C2-ceramide), N-hexanoylsphingosine (C6-ceramide), N-palmitoylsphingosine (C16-ceramide) and D-sphingosine all demonstrated dose-dependent relaxation responses in endothelium-intact vessels. Sphingomyelin signaling through the nitric oxide-dependent mechanism may have an important role in regulating vascular tone.