Human L1 retrotransposon encodes a conserved endonuclease required for retrotransposition

Human L1 elements are highly abundant poly(A) (non-LTR) retrotransposons whose second open reading frame (ORF2) encodes a reverse transcriptase (RT). We have identified an endonuclease (EN) domain at the L1 ORF2 N-terminus that is highly conserved among poly(A) retrotransposons and resembles the apurinic/apyrimidinic (AP) endonucleases. Purified L1 EN protein (L1 ENp) makes 5'-PO4, 3'-OH nicks in supercoiled plasmids, shows no preference for AP sites, and preferentially cleaves sequences resembling L1 in vivo target sequences. Mutations in conserved amino acid residues of L1 EN abolish its nicking activity and eliminate L1 retrotransposition. We propose that L1 EN cleaves the target site for L1 insertion and primes reverse transcription.

Methylation of histone H4 at arginine 3 facilitating transcriptional activation by nuclear hormone receptor

Acetylation of core histone tails plays a fundamental role in transcription regulation. In addition to acetylation, other posttranslational modifications, such as phosphorylation and methylation, occur in core histone tails. Here, we report the purification, molecular identification, and functional characterization of a histone H4-specific methyltransferase PRMT1, a protein arginine methyltransferase. PRMT1 specifically methylates arginine 3 (Arg 3) of H4 in vitro and in vivo. Methylation of Arg 3 by PRMT1 facilitates subsequent acetylation of H4 tails by p300. However, acetylation of H4 inhibits its methylation by PRMT1. Most important, a mutation in the S-adenosyl-l-methionine-binding site of PRMT1 substantially crippled its nuclear receptor coactivator activity. Our finding reveals Arg 3 of H4 as a novel methylation site by PRMT1 and indicates that Arg 3 methylation plays an important role in transcriptional regulation.

The clinical pharmacogenetics implementation consortium guideline for SLCO1B1 and simvastatin-induced myopathy: 2014 update

Simvastatin is among the most commonly used prescription medications for cholesterol reduction. A single coding single-nucleotide polymorphism, rs4149056T>C, in SLCO1B1 increases systemic exposure to simvastatin and the risk of muscle toxicity. We summarize evidence from the literature supporting this association and provide therapeutic recommendations for simvastatin based on SLCO1B1 genotype. This article is an update to the 2012 Clinical Pharmacogenetics Implementation Consortium guideline for SLCO1B1 and simvastatin-induced myopathy.

A Saccharomyces gene family involved in invasive growth, cell-cell adhesion, and mating

The cell wall of bakers' yeast contains a family of glycosyl-phosphatidylinositol (GPI)-linked glycoproteins of domain structure similar to the adhesins of pathogenic fungi. In wild-type cells each of these proteins has a unique function in different developmental processes (mating, invasive growth, cell-cell adhesion, or filamentation). What unifies these developmental events is adhesion, either to an inert substrate or to a cell. Although they differ in their specificities, many of these proteins can substitute for each other when overexpressed. For example, Flo11p is required during vegetative growth for haploid invasion and diploid filamentation, whereas Fig2p is required for mating. When overexpressed, Flo11p and Fig2p can function in mating, invasion, filamentation, and flocculation. The ability of Flo11p to supply Fig2p function in mating depends on its intracellular localization to the mating projection, where Fig2p normally functions in the adhesion of mating cells. Our data show that even distant family members retain the ability to carry out disparate functions if localized and expressed appropriately.

Ras signaling is required for serum-induced hyphal differentiation in Candida albicans

Serum induces Candida albicans to make a rapid morphological change from the yeast cell form to hyphae. Contrary to the previous reports, we found that serum albumin does not play a critical role in this morphological change. Instead, a filtrate (molecular mass, <1 kDa) devoid of serum albumin induces hyphae. To study genes controlling this response, we have isolated the RAS1 gene from C. albicans by complementation. The Candida Ras1 protein, like Ras1 and Ras2 of Saccharomyces cerevisiae, has a long C-terminal extension. Although RAS1 appears to be the only RAS gene present in the C. albicans genome, strains homozygous for a deletion of RAS1 (ras1-2/ras1-3) are viable. The Candida ras1-2/ras1-3 mutant fails to form germ tubes and hyphae in response to serum or to a serum filtrate but does form pseudohyphae. Moreover, strains expressing the dominant active RAS1(V13) allele manifest enhanced hyphal growth, whereas those expressing a dominant negative RAS1(A16) allele show reduced hyphal growth. These data show that low-molecular-weight molecules in serum induce hyphal differentiation in C. albicans through a Ras-mediated signal transduction pathway.

The clinical pharmacogenomics implementation consortium: CPIC guideline for SLCO1B1 and simvastatin-induced myopathy

Cholesterol reduction from statin therapy has been one of the greatest public health successes in modern medicine. Simvastatin is among the most commonly used prescription medications. A non-synonymous coding single-nucleotide polymorphism (SNP), rs4149056, in SLCO1B1 markedly increases systemic exposure to simvastatin and the risk of muscle toxicity. This guideline explores the relationship between rs4149056 (c.521T>C, p.V174A) and clinical outcome for all statins. The strength of the evidence is high for myopathy with simvastatin. We limit our recommendations accordingly.

Increased inducible nitric oxide synthase expression contributes to myocardial dysfunction and higher mortality after myocardial infarction in mice

BACKGROUND

Inducible nitric oxide synthase (iNOS) is expressed in the myocardium after myocardial infarction (MI) and in heart failure. Its pathophysiological role in these conditions, however, is not clear. We hypothesized that increased NO production from iNOS expression causes myocardial dysfunction and results in higher mortality after MI.

METHODS AND RESULTS

MI was induced by left coronary artery ligation in iNOS(-/-) mutant and wild-type mice. Mortality was followed up for 30 days. MI resulted in a significant increase in mortality in both iNOS(-/-) and wild-type mice compared with sham operation (P<0.01). Mortality was significantly decreased and LV myocardial contractility was increased, however, in iNOS(-/-) mice compared with the wild-type mice (P<0.05). Five days after MI, myocardial iNOS mRNA expression, plasma nitrate and nitrite concentrations, and myocardial and plasma nitrotyrosine levels were significantly increased in wild-type compared with iNOS(-/-) mutant mice (P<0.05). Both basal LV +dP/dt and its response to dobutamine were significantly increased in iNOS(-/-) compared with the wild-type mice (P<0.05).

CONCLUSIONS

Increased NO production from iNOS expression contributes to myocardial dysfunction and mortality after MI in mice.

Methylation of the protein phosphatase 2A catalytic subunit is essential for association of Balpha regulatory subunit but not SG2NA, striatin, or polyomavirus middle tumor antigen

Binding of different regulatory subunits and methylation of the catalytic (C) subunit carboxy-terminal leucine 309 are two important mechanisms by which protein phosphatase 2A (PP2A) can be regulated. In this study, both genetic and biochemical approaches were used to investigate regulation of regulatory subunit binding by C subunit methylation. Monoclonal antibodies selectively recognizing unmethylated C subunit were used to quantitate the methylation status of wild-type and mutant C subunits. Analysis of 13 C subunit mutants showed that both carboxy-terminal and active site residues are important for maintaining methylation in vivo. Severe impairment of methylation invariably led to a dramatic decrease in Balpha subunit binding but not of striatin, SG2NA, or polyomavirus middle tumor antigen (MT) binding. In fact, most unmethylated C subunit mutants showed enhanced binding to striatin and SG2NA. Certain carboxy-terminal mutations decreased Balpha subunit binding without greatly affecting methylation, indicating that Balpha subunit binding is not required for a high steady-state level of C subunit methylation. Demethylation of PP2A in cell lysates with recombinant PP2A methylesterase greatly decreased the amount of C subunit that could be coimmunoprecipitated via the Balpha subunit but not the amount that could be coimmunoprecipitated with Aalpha subunit or MT. When C subunit methylation levels were greatly reduced in vivo, Balpha subunits were found complexed exclusively to methylated C subunits, whereas striatin and SG2NA in the same cells bound both methylated and unmethylated C subunits. Thus, C subunit methylation is critical for assembly of PP2A heterotrimers containing Balpha subunit but not for formation of heterotrimers containing MT, striatin, or SG2NA. These findings suggest that methylation may be able to selectively regulate the association of certain regulatory subunits with the A/C heterodimer.

Predictive action in infancy: tracking and reaching for moving objects

Because action plans must anticipate the states of the world which will be obtained when the actions take place, effective actions depend on predictions. The present experiments begin to explore the principles underlying early-developing predictions of object motion, by focusing on 6-month-old infants' head tracking and reaching for moving objects. Infants were presented with an object that moved into reaching space on four trajectories: two linear trajectories that intersected at the center of a display and two trajectories containing a sudden turn at the point of intersection. In two studies, infants' tracking and reaching provided evidence for an extrapolation of the object motion on linear paths, in accord with the principle of inertia. This tendency was remarkably resistant to counter-evidence, for it was observed even after repeated presentations of an object that violated the principle of inertia by spontaneously stopping and then moving in a new direction. In contrast to the present findings, infants fail to extrapolate linear object motion in preferential looking experiments, suggesting that early-developing knowledge of object motion, like mature knowledge, is embedded in multiple systems of representation.

Etoposide and cisplatin versus paclitaxel and carboplatin with concurrent thoracic radiotherapy in unresectable stage III non-small cell lung cancer: a multicenter randomized phase III trial

Background

The optimal chemotherapy regimen administered currently with radiation in patients with stage III non-small cell lung cancer (NSCLC) remains unclear. A multicenter phase III trial was conducted to compare the efficacy of concurrent thoracic radiation therapy with either etoposide/cisplatin (EP) or carboplatin/paclitaxel (PC) in patients with stage III NSCLC.

Patients and methods

Patients were randomly received 60-66 Gy of thoracic radiation therapy concurrent with either etoposide 50 mg/m2 on days 1-5 and cisplatin 50 mg/m2 on days 1 and 8 every 4 weeks for two cycles (EP arm), or paclitaxel 45 mg/m2 and carboplatin (AUC 2) on day 1 weekly (PC arm). The primary end point was overall survival (OS). The study was designed with 80% power to detect a 17% superiority in 3-year OS with a type I error rate of 0.05.

Results

A total of 200 patients were randomized and 191 patients were treated (95 in the EP arm and 96 in the PC arm). With a median follow-up time of 73 months, the 3-year OS was significantly higher in the EP arm than that of the PC arm. The estimated difference was 15.0% (95% CI 2.0%-28.0%) and P value of 0.024. Median survival times were 23.3 months in the EP arm and 20.7 months in the PC arm (log-rank test P = 0.095, HR 0.76, 95%CI 0.55-1.05). The incidence of Grade ≥2 radiation pneumonitis was higher in the PC arm (33.3% versus 18.9%, P = 0.036), while the incidence of Grade ≥3 esophagitis was higher in the EP arm (20.0% versus 6.3%, P = 0.009).

Conclusion

EP might be superior to weekly PC in terms of OS in the setting of concurrent chemoradiation for unresectable stage III NSCLC.

Trial registration ID

NCT01494558.

Tembusu virus in human, China

SUMMARY

Tembusu virus (TMUV) infection in ducks, geese and house sparrows was reported in China. To confirm the emergence of TMUV in humans, we investigated TMUV as a possible infection in duck industry workers in Shandong, China. Of 132 serum samples tested, 95 (71.9%) had TMUV antibodies. In oral swabs detection, 63 (47.7%) samples were positive for TMUV RNA. Nucleotide sequences of 277 bp coding the partial NS3 protein showed more than 99.5% identity with other duck TMUV strains, which can cause severe egg drop in ducks. These findings contribute to the realization that TMUV may be overlooked as a zoonotic transmission in China.

Tumor necrosis factor-alpha induces apoptosis via inducible nitric oxide synthase in neonatal mouse cardiomyocytes

OBJECTIVE

It has been demonstrated that tumor necrosis factor-alpha (TNF alpha) induces apoptosis in cardiac myocytes. However, its mechanism of action is still not well understood. In the present study, we hypothesized that TNF alpha induces myocardial apoptosis by induction of inducible nitric oxide synthase (iNOS).

METHODS

Neonatal cardiac myocytes were isolated from iNOS (-/-) mutant and C57BL6 wild type mice. Cells were cultured for 3 days before treatment with an NO donor or TNF alpha. Following treatment with S-nitroso-N-acetyl-penicillamine (SNAP) or TNF-alpha, cells were tested for apoptosis by terminal deoxynucleotidyl transfer-mediated end labeling (TUNEL) staining and cell death detection ELISA. NO production was measured by nitrite concentration in the culture medium. Cardiomyocyte expression of iNOS and TNF type 1 receptor (TNFR1) mRNA was determined by reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

SNAP (0.01-100 microM) induced apoptosis of cardiac myocytes in a concentration-dependent manner in the wild type mice (n = 5, P < 0.01). TNFR1 mRNA was expressed in neonatal cardiomyocytes from both wild type and iNOS (-/-) mutant mice. TNF alpha induced a concentration-dependent increase in iNOS mRNA expression and nitrite production as well as significant apoptosis of cardiomyocytes in the wild type mice (n = 4, P < 0.01). However, without iNOS expression, the apoptotic effects of TNF-alpha were significantly attenuated in cardiomyocytes from iNOS (-/-) mutant mice (n = 4, P < 0.05).

CONCLUSION

TNF alpha induces apoptosis via iNOS expression and NO production in neonatal mouse cardiomyocytes.

Human ovarian cancer and cisplatin resistance: possible role of inhibitor of apoptosis proteins

The inhibitor of apoptosis proteins (IAPs) constitutes a family of highly conserved apoptosis suppressor proteins that were originally identified in baculoviruses. Although IAP homologs have recently been demonstrated to suppress apoptosis in mammalian cells, their expression and role in human ovarian epithelial cancer and chemotherapy resistance are unknown. In the present study we used cisplatin-sensitive and -resistant human ovarian surface epithelial (hOSE) cancer cell lines and adenoviral antisense and sense complementary DNA expression to examine the role of IAP in the regulation of apoptosis in human ovarian cancer cells and chemoresistance. Antisense down-regulation of X-linked inhibitor of apoptosis protein (Xiap), but not human inhibitor of apoptosis protein-2 (Hiap-2), induced apoptosis in cisplatin-sensitive and, to a lesser extent, in -resistant cells. Cisplatin consistently decreased Xiap content and induced apoptosis in the cisplatin-sensitive, but not cisplatin-resistant, cells. Hiap-2 expression was either unaffected or inhibited to a lesser extent. The inhibition of IAP protein expression and induction of apoptosis by cisplatin was time and concentration dependent. Infection of cisplatin-sensitive cells with adenoviral sense Xiap complementary DNA resulted in overexpression of Xiap and markedly attenuated the ability of cisplatin to induce apoptosis. Immunohistochemical localization of the IAPs in hOSE tumors demonstrated the presence of Xiap and Hiap-2, with their levels being highest in proliferative, but not apoptotic, epithelial cells. These studies indicate that Xiap is an important element in the control of ovarian tumor growth and may be a point of regulation for cisplatin in the induction of apoptosis. These results suggest that the ability of cisplatin to down-regulate Xiap content may be an important determinant of chemosensitivity in hOSE cancer.

Competition, cooperation, and mutation: improving a synthetic replicator by light irradiation

Replication and mutation are necessary elements of evolution, and some properties of self-replicating molecules (replicators) can be explored with synthetic structures. Selection and evolution at the molecular level require systems capable of competition and inheritable change. These phenomena have now been observed with synthetic molecules. Two such molecules were prepared having sufficient structural similarity that they catalyzed each other's formation as well as their own. One of the replicators bears a photochemically active function that is cleaved on irradiation. The resulting species is more effective at replication than the original and rapidly takes over the system's resources.

Elevation of an endogenous inhibitor of nitric oxide synthesis in experimental congestive heart failure

OBJECTIVE

NG,NG-dimethylarginine (asymmetric dimethylarginine, ADMA) is an important endogenous substance with potent inhibitory actions on nitric oxide (NO) synthesis. The present study was designed to determine circulating ADMA levels and endothelium-dependent, NO mediated vasodilation in a rat model of congestive heart failure (CHF).

METHODS

CHF was induced in rats by coronary artery ligation. Sham-operated rats served as normal controls. Plasma ADMA was determined by high performance liquid chromatography with fluorescence detection. Glomerular filtration rate (GFR) and renal blood flow (RBF) were measured by the clearance of inulin and p-aminohippuric acid, respectively. Endothelial function of the aorta was assessed in an organ bath.

RESULTS

Plasma levels of ADMA in rats with CHF (0.94 +/- 0.05 mumol/l) were significantly increased compared with sham-operated controls (0.75 +/- 0.06 mumol/l, p < 0.05). Plasma levels of ADMA was negatively correlated with GFR (r = -0.65, p < 0.05). Decreased endothelium-dependent relaxation to acetylcholine in the aorta of CHF was completely restored by L-arginine (300 microM) (p < 0.01) while endothelium-independent relaxation to nitroprusside was not altered. ADMA potently inhibited endothelium-dependent relaxation in thoracic aorta of normal and CHF rats. The effect of ADMA was completely antagonized by L-arginine in both groups (p < 0.01). Moreover, L-arginine improved endothelium-dependent relaxation in CHF rats in the presence of ADMA.

CONCLUSIONS

An endogenous NO synthesis inhibitor ADMA is increased in the circulation of rats with CHF. The increased plasma levels of ADMA may contribute to the decreased endothelium-dependent relaxation in CHF, which is restored by L-arginine, possibly by competitive antagonism of ADMA.

Selective CD28 blockade attenuates acute and chronic rejection of murine cardiac allografts in a CTLA-4-dependent manner

Selective blockade of CD28 is a promising therapy to inhibit pathogenic alloimmunity. However, evaluation of this approach in transplantation has been very limited. Using a novel nonactivating single-chain Fv-based reagent (α28scFv), we have investigated the role of CD28 and cytotoxic T lymphocyte antigen 4 (CTLA-4) in a murine cardiac transplant model. Blockade of CD28 for 2 weeks after engraftment promoted allograft survival, and significantly attenuated chronic rejection when combined with transient CD154-blockade or calcineurin inhibition. Graft acceptance was associated with decreased alloantibody production, increased proportion of early graft infiltration by regulatory T cells and increased expression of regulatory dendritic cell genes. Blockade of CTLA-4 during α28scFv-based treatments led to prompt rejection in all animals and inhibited expression of forkhead box P3 (Foxp3), programmed death (PD)-1 and 2,3-indoleamine dioxygenase (IDO) in the graft. These results show that CD28 signaling during the first weeks after transplant is a pivotal mediator of pathogenic alloimmunity, and that selective CD28 blockade prolongs graft acceptance by at least two immunomodulatory mechanisms. Selective CD28 inhibition while sparing CTLA-4 is thus a promising approach to inhibit pathogenic alloimmunity.

Retrotransposon R1Bm endonuclease cleaves the target sequence

The R1Bm element, found in the silkworm Bombyx mori, is a member of a group of widely distributed retrotransposons that lack long terminal repeats. Some of these elements are highly sequence-specific and others, like the human L1 sequence, are less so. The majority of R1Bm elements are associated with ribosomal DNA (rDNA). R1Bm inserts into 28S rDNA at a specific sequence; after insertion it is flanked by a specific 14-bp target site duplication of the 28S rDNA. The basis for this sequence specificity is unknown. We show that R1Bm encodes an enzyme related to the endonuclease found in the human L1 retrotransposon and also to the apurinic/apyrimidinic endonucleases. We expressed and purified the enzyme from bacteria and showed that it cleaves in vitro precisely at the positions in rDNA corresponding to the boundaries of the 14-bp target site duplication. We conclude that the function of the retrotransposon endonucleases is to define and cleave target site DNA.

Laparoscopy-assisted vs. open total gastrectomy for advanced gastric cancer: long-term outcomes and technical aspects of a case-control study

BACKGROUND AND OBJECTIVES

An increasing number of studies comparing laparoscopy-assisted distal gastrectomy and conventional open distal gastrectomy have been reported; the technical feasibility and clinical efficacy have been confirmed. However, few data are available to compare laparoscopy-assisted total gastrectomy (LATG) and open techniques for the treatment of advanced gastric cancer (AGC). The aim of this study is to compare the oncologic efficacy and long-term outcomes of LATG vs. open total gastrectomy (OTG) for AGC and to provide our experiences regarding these surgical difficulties as well.

METHODS

Using data from a clinical database of all operations performed in our department by a special surgical team, we retrospectively analysed data from 117 cases of LATG and matched OTG performed between January 2004 and December 2010. This analysis was a case-control study in which patients in the two groups were matched according to tumour location, age, gender, BMI and TNM stage via a propensity score matching method. Patient clinical characteristics, lymph node retrieval, early postoperative complications, recurrence and long-term outcomes were compared.

RESULTS

The demographics, preoperative data and characteristics of the tumour were similar in both groups. No significant differences were found in the LATG group compared with the OTG group with regard to the number of retrieved lymph nodes or distance from the proximal margin. Operating time was longer in the LATG group than in the OTG group (292.8 ± 49.5 vs. 242.1 ± 47.4, p < 0.05). Significant differences were found between LATG and OTG with regard to blood loss, postoperative hospitalisation and times of analgesic injection. The early postoperative complication rates in the LATG group were significantly lower than in the OTG group (11.1 vs. 16.3 %, p < 0.05). Operative mortality was zero in both groups. During a median follow-up of 61.2 (range, 6-84) months, the overall 5-year survival rates in the LATG group and OTG group were 49.3 and 46.5 %, respectively; there was no significant difference between the two groups (p = 0.756).

CONCLUSION

Our results suggest that LATG is technically feasible for advanced gastric cancer patients and can yield good short- and long-term oncologic outcomes as compared with conventional OTG.

Crossover reactions between synthetic replicators yield active and inactive recombinants

Self-replicating molecules can be synthesized through the covalent linkage of two complementary subunits to give a self-complementary structure. Complementarity refers to sizes, shapes, and the weak intermolecular forces involved in molecular recognition between the two subunits. In order to provide a model system for evolution at the molecular level, "crossover" or recombination experiments were staged with synthetic replicators. These reactions gave rise to new structural types. The ability (or inability) of the new recombinants to catalyze their own formation is shown to be a consequence of their molecular shapes.

Comparison of laparoscopically assisted and open radical distal gastrectomy with extended lymphadenectomy for gastric cancer management

BACKGROUND

The feasibility and safety of laparoscopically assisted gastrectomy with extended lymphadenectomy for advanced gastric cancer has rarely been studied. This study aimed to investigate the feasibility, safety, and cancer clearance of laparoscopically assisted distal gastrectomy with D2 lymphadenectomy.

METHODS

Of the 44 patients with distal gastric cancer who underwent radical distal gastrectomy from March 2004 to May 2005, 35 were treated with D2/D2(+) lymphadenectomy. These patients were compared with 58 patients who, during the same period, underwent a conventional open radical distal gastrectomy.

RESULTS

The mean total number of retrieved lymph nodes (30.11 +/- 16.97) and the mean tumor margin were comparable with those in the open group. The mean operative time for laparoscopically assisted distal gastrectomy was significantly longer than for open surgery (282.84 +/- 32.81 min vs 223.75 +/- 23.25 min). The patients in the laparoscopic surgery group had less blood loss, shorter times of analgesic injection, and a faster recovery. The rates of complications were comparable between two groups.

CONCLUSIONS

Although laparoscopically assisted radical gastrectomy with D2 lymphadenectomy is more time consuming than open surgery, it is a safe, feasible procedure that achieves cancer clearance similar to open surgery and leads to a quick postoperative recovery.

Anticarcinogenic antioxidants as inhibitors against intracellular oxidative stress

Oxidative stress has been implicated in the pathogenesis of numerous diseases, including cancer. In the present study, the protective effect of natural antioxidants, such as quercetin and tea polyphenols, on intracellular oxidative stress was studied. Here we report a novel function of quercetin and tea polyphenols, as potential inhibitors of 4-hydroxy-2-nonenal (HNE)-induced intracellular oxidative stress and cytotoxicity. In rat liver epithelial RL34 cells, a potent electrophile HNE dramatically induced the productions of reactive oxygen species (ROS), which correlated well with the reduction in cell viability. We found that quercetin and tea polyphenols, such as epigallocatechin gallate and theaflavins and their gallate esters, significantly inhibited the HNE-induced ROS production and cytotoxicity. In addition, HNE induced a transient decrease in the mitochondrial membrane potential (delta psi), which was also retarded by the antioxidants. These data suggest that the antioxidants, such as quercetin and tea polyphenols, are inhibitors against mitochondrial ROS production.