Activation of the STAT6 transcription factor in Jurkat T-cells by the herpesvirus saimiri Tip protein

Herpesvirus saimiri (HVS), a T-lymphotropic monkey herpesvirus, induces fulminant T-cell lymphoma in non-natural primate hosts. In addition, it can immortalize human T-cells in vitro. HVS tyrosine kinase-interacting protein (Tip) is an essential viral gene required for T-cell transformation both in vitro and in vivo. In this study, we found that Tip interacts with the STAT6 transcription factor and induces phosphorylation of STAT6 in T-cells. The interaction with STAT6 requires the Tyr(127) residue and Lck-binding domain of Tip, which are indispensable for interleukin (IL)-2-independent T-cell transformation by HVS. It was also demonstrated that Tip induces nuclear translocation of STAT6, as well as activation of STAT6-dependent transcription in Jurkat T-cells. Interestingly, the phosphorylated STAT6 mainly colocalized with vesicles containing Tip within T-cells, but was barely detectable in the nucleus. However, nuclear translocation of phospho-STAT6 and transcriptional activation of STAT6 by IL-4 stimulation were not affected significantly in T-cells expressing Tip. Collectively, these findings suggest that the constitutive activation of STAT6 by Tip in T-cells may contribute to IL-2-independent T-cell transformation by HVS.

Systems biology and epigenetic gene regulation

Epigenetics is the study of regulatory mechanisms that are not accompanied by the action of genetic elements. Recently, a system-wide extension of epigenetics has been driven by the rapid evolution of genomics technology. This means not simply profiling multiple genes together as gene expression microarrays, but also factoring in the crosstalk among various epigenetic components and extending our focus to relatively uncharted genomic areas, including intergenic and intragenic regions. Although this exciting extension provides many interesting research topics as described in this review, the future expansion of epigenomics to cover multiple samples will offer an even more profound opportunity for systems biology research.

Caudal epidural block in children: comparison of needle insertion parallel with caudal canal versus conventional two-step technique

This study compared the technique of inserting the needle for caudal epidural blockade in a single pass parallel to the caudal canal versus the conventional technique of approaching the caudal canal with the needle at a steeper angle. Seventy-five patients, aged 0 to 72 months, scheduled for urological surgery were prospectively enrolled in this study. Patients were randomly divided into two groups: a conventional method group (caudal block performed with conventional needle insertion, n=40) and a new method group (needle inserted into the skin at an angle of 200 and into the caudal space without redirection, n=35). Two anaesthetists (A, B) performed the caudal blocks. For anaesthetist A, the mean time required (standard deviation) to perform needle insertion in the conventional method group was 2.2 (0.8) minutes and in the new method group 1.1 (0.7) minutes (P = 0.03). For anaesthetist B the mean time (standard deviation) to perform needle insertion in the conventional method group was 2.1 (1.1) minutes and in the new method group 1.3 (0.8) minutes (P = 0.04). Successful block was considered as first pass placement of the needle in the caudal canal confirmed (after placement) by ultrasound imaging, and the absence of a bloody tap. Subcutaneous placement of the needle after the first attempt occurred in two cases in the conventional method group and three cases in the new method group. Bloody tap occurred in four cases, all in the conventional method group and none in the new method group. When required, the second pass was successful in all cases.

Direct interaction of cellular hnRNP-F and NS1 of influenza A virus accelerates viral replication by modulation of viral transcriptional activity and host gene expression

To investigate novel NS1-interacting proteins, we conducted a yeast two-hybrid analysis, followed by co-immunoprecipitation assays. We identified heterogeneous nuclear ribonucleoprotein F (hnRNP-F) as a cellular protein interacting with NS1 during influenza A virus infection. Co-precipitation assays suggest that interaction between hnRNP-F and NS1 is a common and direct event among human or avian influenza viruses. NS1 and hnRNP-F co-localize in the nucleus of host cells, and the RNA-binding domain of NS1 directly interacts with the GY-rich region of hnRNP-F determined by GST pull-down assays with truncated proteins. Importantly, hnRNP-F expression levels in host cells indicate regulatory role on virus replication. hnRNP-F depletion by small interfering RNA (siRNA) shows 10- to 100-fold increases in virus titers corresponding to enhanced viral RNA polymerase activity. Our results delineate novel mechanism of action by which NS1 accelerates influenza virus replication by modulating normal cellular mRNA processes through direct interaction with cellular hnRNP-F protein.

Jab1/CSN5 induces the cytoplasmic localization and degradation of RUNX3

Runt-related (RUNX) transcription factors play pivotal roles in neoplastic development and have tissue-specific developmental roles in hematopoiesis (RUNX1), osteogenesis (RUNX2), as well as neurogenesis and thymopoiesis (RUNX3). RUNX3 is a tumor suppressor in gastric carcinoma, and its expression is frequently inactivated by DNA methylation or its protein mislocalized in many cancer types, including gastric and breast cancer. Jun-activation domain-binding protein 1 (Jab1/CSN5), a component of the COP9 signalosome (CSN), is critical for nuclear export and the degradation of several tumor suppressor proteins, including p53, p27(Kip1), and Smad4. Here, we find that Jab1 facilitates nuclear export of RUNX3 that is controlled by CSN-associated kinases. RUNX3 sequestered in the cytoplasm is rapidly degraded through a proteasome-mediated pathway. Our results identify a novel mechanism of regulating nuclear export and protein stability of RUNX3 by the CSN complex.

Enhanced cytotoxicity of 5-FU by bFGF through up-regulation of uridine phosphorylase 1

Anti cancer agent 5-FU (Fluoro Uracil) is a prodrug that can be metabolized and then activated to interfere with RNA and DNA homeostasis. However, the majority of administered 5-FU is known to be catabolized in vivo in the liver where Dihydropyrimidine dehydrogenase (DPD) is abundantly expressed to degrade 5-FU. The biological factors that correlate with the response to 5-FU-based chemotherapy have been proposed to include uridine phosphorylase (UPP), thymidine phosphorylase (TPP), p53 and microsatellite instability. Among these, the expression of UPP is known to be controlled by cytokines such as TNF-alpha, IL1 and IFN-gamma. Our preliminary study using a DNA microarray technique showed that basic fibroblast growth factor (bFGF) markedly induced the expression of UPP1 at the transcription level. In the present study, we investigated whether bFGF could modulate the expression of UPP1 in osteo-lineage cells and examined the sensitivity of these cells to 5-FU mediated apoptosis.

A robust xenotransplantation model for acute myeloid leukemia

Xenotransplantation of human acute myeloid leukemia (AML) in immunocompromised animals has been critical for defining leukemic stem cells. However, existing immunodeficient strains of mice have short life spans and low levels of AML cell engraftment, hindering long-term evaluation of primary human AML biology. A recent study suggested that NOD/LtSz-scid IL2Rgammac null (NSG) mice have enhanced AML cell engraftment, but this relied on technically challenging neonatal injections. Here, we performed extensive analysis of AML engraftment in adult NSG mice using tail vein injection. Of the 35 AML samples analyzed, 66% showed bone marrow engraftment over 0.1%. Further, 37% showed high levels of engraftment (>10%), with some as high as 95%. A 2-44-fold expansion of AML cells was often seen. Secondary and tertiary recipients showed consistent engraftment, with most showing further AML cell expansion. Engraftment did not correlate with French-American-British subtype or cytogenetic abnormalities. However, samples with FLT3 mutations showed a higher probability of engraftment than FLT3 wild type. Importantly, animals developed organomegaly and a wasting illness consistent with advanced leukemia. We conclude that the NSG xenotransplantation model is a robust model for human AML cell engraftment, which will allow better characterization of AML biology and testing of new therapies.

Efficacy of low-calorie, partial meal replacement diet plans on weight and abdominal fat in obese subjects with metabolic syndrome: a double-blind, randomised controlled trial of two diet plans - one high in protein and one nutritionally balanced

BACKGROUND

Little is known about the relative efficacy of high-protein vs. conventional diet plans that include partial meal replacements on body fat loss in obese subjects with metabolic syndrome.

OBJECTIVE

We aimed to evaluate the efficacy of two low-calorie diets with partial meal replacement plans-a high-protein plan (HP) and a nutritionally balanced conventional (C) plan-on reducing obesity in obese subjects with metabolic syndrome.

DESIGN

In a 12-week, double-blind study, we randomised 75 participants to either the HP- or the C-plan group. We recorded key metrics at 0 and 12 weeks.

RESULTS

The overall mean weight loss was 5 kg in the HP-plan group and 4.9 kg in the C-plan group (p = 0.72). Truncal fat mass decreased 1.6 kg in the HP-plan group (p < 0.05) and 1.5 kg in the C-plan group (p < 0.05), while whole body fat mass decreased 2.5 kg in the HP-plan group (p < 0.05) and 2.3 kg in the C-plan group (p < 0.05). Between-group losses did not differ significantly for truncal (p = 0.52) or whole body (p = 0.77) fat mass. Among subjects with > or = 70% dietary compliance, however, truncal and whole body fat mass decreased more in the HP-plan group (Delta 2.2 kg and Delta 3.5 kg respectively) than in the C-plan group (Delta 1.3 kg and Delta 2.3 [corrected] kg respectively) (p < 0.05).

CONCLUSION

The HP- and C-plans had a similar effect on weight and abdominal fat reduction, but the HP-plan was more effective in reducing body fat among compliant subjects.

Multi-transmembrane protein K15 of Kaposi's sarcoma-associated herpesvirus targets Lyn kinase in the membrane raft and induces NFAT/AP1 activities

Viral proteins of gamma-2 herpesviruses, such as LMP2A of Epstein Barr virus (EBV) and Tip of herpesvirus saimiri (HVS) dysregulate lymphocyte signaling by interacting with Src family kinases. K15 open reading frame of Kaposi's sarcoma associated herpesvirus (KSHV), located at the right end of the viral genome, encodes several splicing variants differing in numbers of transmembrane domains. Previously, we demonstrated that the cytoplasmic tail of the K15 protein interfered with B cell receptor signal transduction to cellular tyrosine phosphorylation and calcium mobilization. However, the detailed mechanism underlying this phenomenon was not understood. In the C-terminal cytoplasmic region of K15, putative binding domains for Src-SH2 and -SH3 were identified. In this study, we attempted to characterize these modular elements and cellular binding protein(s) by GST pull down and co-immunoprecipitation assays. These studies revealed that K15 interacted with the major B cell tyrosine kinase Lyn. In vitro kinase and transient co-expression assays showed that the expression of K15 protein resulted in activation of Lyn kinase activity. In addition, GST pull down assay suggested that the SH2 domain of Lyn alone was necessary for interaction with the C-terminal SH2B (YEEV) of K15, but the addition of Lyn SH3 to the SH2 domain increases the binding affinity to K15 protein. The data from luciferase assays indicate that K15 expression in BJAB cells induced NFAT and AP1 activities. The tyrosine residue in the C-terminal end of K15 required for the Lyn interaction appeared to be essential for NFAT/AP1 activation, highlighting the significance of the C-terminal SH2B of K15 as a modular element in interfering with B lymphocyte signaling through interaction with Lyn kinase.

Identification of osteogenic purmorphamine derivatives

During embryonic and cancer development, the Hedgehog family of proteins, including Sonic Hedgehog, play an important role by relieving the inhibition of Smo by Ptc, thus activating the Smo signaling cascade. Recently, a purine compound, purmorphamine, has been reported to target the Hedgehog signaling pathway by interacting with Smo. Interestingly, both Sonic Hedgehog and purmorphamine were found to promote the osteogenic differentiation of mouse chondroprogenitor cells. However, there is insufficient information as to how the activation of this seemingly unrelated signaling pathway, either by Sonic Hedgehog or purmorphamine, contributes to osteogenesis. Using alkaline phosphatase assays, we screened 125 purmorphamine derivatives from the Korea Chemical Bank for effects on the differentiation of preosteoblast C2C12 cells. Here, we report that two purine derivatives modulate ALP activity as well as the expression of genes whose expression is known or suggested to be involved in osteogenesis.

Gamma c-signaling cytokines induce a regulatory T cell phenotype in malignant CD4+ T lymphocytes

In this study, we demonstrate that malignant mature CD4(+) T lymphocytes derived from cutaneous T cell lymphomas (CTCL) variably display some aspects of the T regulatory phenotype. Whereas seven cell lines representing a spectrum of primary cutaneous T cell lymphoproliferative disorders expressed CD25 and TGF-beta, the expression of FOXP3 and, to a lesser degree, IL-10 was restricted to two CTCL cell lines that are dependent on exogenous IL-2. IL-2, IL-15, and IL-21, all of which signals through receptors containing the common gamma chain, induced expression of IL-10 in the IL-2-dependent cell lines as well as primary leukemic CTCL cells. However, only IL-2 and IL-15, but not IL-21, induced expression of FOXP3. The IL-2-triggered induction of IL-10 and FOXP3 expression occurred by signaling through STAT3 and STAT5, respectively. Immunohistochemical analysis of the CTCL tissues revealed that FOXP3-expressing cells were common among the CD7-negative enlarged atypical and small lymphocytes at the early skin patch and plaque stages. Their frequency was profoundly diminished at the tumor stage and in the CTCL lymph node lesions with or without large cell transformation. These results indicate that the T regulatory cell features are induced in CTCL T cells by common gamma chain signaling cytokines such as IL-2 and do not represent a fully predetermined, constitutive phenotype independent of the local environmental stimuli to which these malignant mature CD4(+) T cells become exposed.

Infection of soybean by cucumber mosaic virus as determined by viral movement protein

To characterize the host range determinant of the soybean strain of Cucumber mosaic virus (CMV) we analyzed a series of pseudorecombinants and chimeric viruses between infectious transcripts from two soybean strains (CMV-SC and CMV-SD) and an ordinary strain (CMV-Y). CMV-Y could not infect soybeans, even locally. Systemic infection of the two soybean-adapted soybean isolates on soybean plants mapped to RNA3. Chimeric RNA3s from between CMV-SC and CMV-Y, and chimeric RNA3s from between CMV-SC and CMV-SD, were made and inoculated onto wild soybean Iwate and soybean cv. Tsurunoko. The 3a region determined the viral systemic movement in the plants. In the wild soybean ecotype Hyougo, cell-to-cell movement of two different CMV soybean strains, one of which infects systemically while the other does not, in the inoculated leaves were almost the same, suggesting that the resistance of soybean operates at the level of long-distance movement. Our results clearly suggest that movement protein is a host determinant of CMV soybean strains.

Isolation and characterization of novel H3N1 swine influenza viruses from pigs with respiratory diseases in Korea

Pigs can play an important role in the genetic reassortment of influenza viruses and as a reservoir for another lineage of influenza viruses that have the ability to reassort and be transmitted between species. In March and April 2006, novel H3N1 influenza A viruses were isolated from pigs with respiratory diseases at two different commercial swine farms in Korea. Genetic and phylogenetic analyses of the sequences of all eight viral RNA segments showed that the novel H3N1 swine influenza viruses were reassortants that acquired the hemagglutinin gene from an H3 human-like virus and other genes from swine influenza viruses that are currently circulating in Korea. Serologic and virologic tests in the infected farms suggested that pig-to-pig and farm-to-farm transmissions occurred. Clinical signs in pigs and experimentally infected mice suggest the potential to transmit the virus between swine and other mammalian hosts. To our knowledge, this is the first report of the isolation of the swine H3N1 subtype from domestic pigs under field conditions in Korea. Further surveillance will be needed to determine whether this novel subtype will continue to circulate in the swine population.

The complete genome sequence of pepper severe mosaic virus and comparison with other potyviruses

The complete nucleotide sequence of pepper severe mosaic virus (PepSMV) was determined. The viral genome consisted of 9890 nucleotides, excluding a poly (A) tract at the 3' end of the genome. The PepSMV RNA genome encoded a single polyprotein of 3085 amino acid residues, resulting in ten functionally distinct potyviral proteins. The lengths of the 5' nontranslated region (NTR) and the 3' NTR were 164 and 468 nucleotides, respectively. The genome organization of the virus was typical for members of the genus Potyvirus in the family Potyviridae. The coat protein amino acid sequence identity between PepSMV and the other 45 potyviruses ranged from 53.4 to 79.7%. Sequence alignments and phylogenetic analyses of the potyviral polyprotein sequences revealed that PepSMV was the closest to potato virus Y (PVY) and closely related to members of the PVY subgroup. Our genome sequence data clearly confirmed that PepSMV belongs to a separate species in the genus Potyvirus.

Degradation kinetics and mechanism of RDX and HMX in TiO2 photocatalysis

This study was undertaken to examine the photocatalytic degradation of explosives hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) with a circular photocatalytic reactor, using a UV lamp as a light source and TiO2 as a photocatalyst. The effects of various parameters, such as the RDX or HMX concentration, the amount of TiO, and the initial pH, on the photocatalytic degradation rates of explosives were examined. In the presence of both UV light and TiO2 RDX and HMX were more effectively degraded than with either UV or TiO2 alone. The degradation rates were found to obey pseudo-first-order kinetics represented by the Langmuir-Hinshelwood model. Increases in the RDX and HMX degradation rates were obtained with decreasing initial concentrations of the explosives. The RDX and HMX degradation rates were higher at pH 7 than at either pH 3 or pH 11. A dose of approximately 0.7 g l(-1) of TiO2 degraded HMX more rapidly than did higher or lower TiO2 doses. RDX (20 mg l(-1)) photocatalysis resulted in an approximately 20% decrease in TOC, and HMX (5 mg l(-1)) photocatalysis resulted in a 60%, decrease in TOC within 150 minutes. A trace amount of formate was produced as an intermediate that was further mineralized by RDX or HMX photocatalysis. The nitrogen byproducts from the photocatalysis of RDX and HMX were mainly NO3- with NO2-, and NH4+. The total nitrogen recovery was about 60% from RDX (20 mg l(-1)), and 70% from HMX (5 mg l(-1)), respectively. Finally, a mechanism for RDX/HMX photocatalysis was proposed, along with supporting qualitative and quantitative evidence.

Protein kinase A phosphorylates and regulates dimerization of 14-3-3 epsilon

Recognition of phosphorylated serine/threonine-containing motifs by 14-3-3 depends on the dimerization of 14-3-3. However, the molecular cues that control 14-3-3 dimerization are not well understood. In order to identify proteins that control 14-3-3 dimerization, we analyzed proteins that have effects on 14-3-3 dimerization and report that protein kinase A (PKA) phosphorylates 14-3-3zeta at a specific residue (Ser58). Phosphorylation by PKA leads to modulation of 14-3-3zeta dimerization and affect its interaction with partner proteins. Substitution of Ser58 to Ala completely abolished phosphorylation of 14-3-3zeta by PKA. A phospho-mimic mutant of 14-3-3zeta, Ser58 to Glu substitution, failed to form homodimers, showed reduced interaction with 14-3-3epsilon and p53, and could not enhance transcriptional activity of p53. Moreover, activation of PKA decreases and inhibition of PKA increases the dimerization of 14-3-3zeta and the functional interaction of 14-3-3zeta with p53. Therefore, our results suggest that PKA is a new member of protein kinases that can phosphorylate and impair the function of 14-3-3.

Deubiquitinating enzyme USP36 contains the PEST motif and is polyubiquitinated

The ubiquitin-mediated protein degradation pathway has been emphasized for the regulation of numerous cellular mechanisms and the significance of deubiquitination, mediated by deubiquitinating (DUB) enzymes, has been emerging as an essential regulatory step to control these cellular mechanisms. Previously, we demonstrated a human DUB enzyme, HeLa DUB-1, expressed in human ovarian cancer cells. Here, we report human USP36, which has the extension of the C-terminal region of HeLa DUB-1 and has conserved amino acid domains as previously shown in other DUBs. Human USP36, encoding a DUB enzyme, was isolated from ovarian cancer cells using RT-PCR and characterized. We identified DUB enzyme activity of USP36 by analyzing its capability to cleave the ubiquitin. Interestingly, structural and immunoprecipitation analyses revealed for the first time that USP36 contains the PEST motif and is polyubiquitinated.

Expression of p50 C-terminal Src kinase (Csk) in mouse testis

C-terminal Src Kinase (Csk) is a cytoplasmic tyrosine kinase that phosphorylates a critical tyrosine residue in each of the Src family kinases to inhibit their activities. To investigate the possible regulation of spermatogenesis by Src-Csk loop, the postnatal changes in the expression of Csk were examined in mouse testes. Semiquantitative RT-PCR analysis revealed that Csk mRNA increased during neonatal development and peaked at 2 weeks of age. Following the decrease during pubertal development, Csk expression re-increased in adult testes. In Western blot, immature testes showed higher expression of Csk protein than the pubertal or adult testes. In immature testis, Csk immunoreactivity was largely found in the Sertoli cell and there was no visible difference in the Csk immunoreactivity among the seminiferous tubules. In adult testis, however, a differential Csk immunoreactivity was found among the seminiferous tubules. Intense signal was found in the adluminal cytoplasm of the Sertoli cells bearing the post-meiotic differentiating germ cells, suggesting that Csk may participate in the remodeling of seminiferous tubule during late phase of spermatogenesis. Csk immunoreactivity was also found in the Leydig cells, suggesting the possible regulation of Leydig cell function. Src-Csk loop may participate in the differentiation of the seminiferous epithelia and Leydig cells in mouse testis.

Transforming Growth Factor-β Stimulates p300-dependent RUNX3 Acetylation, Which Inhibits Ubiquitination-mediated Degradation

The Runt domain transcription factors (RUNXs) play essential roles in normal development and neoplasias. Genetic analyses of animals and humans have revealed the involvement of RUNX1 in hematopoiesis and leukemia, RUNX2 in osteogenesis and cleidocranial dysplasia, and RUNX3 in the development of T-cells and dorsal root ganglion neurons and in the genesis of gastric cancer. Here we report that RUNX3 is a target of the acetyltransferase activity of p300. The p300-dependent acetylation of three lysine residues protects RUNX3 from ubiquitin ligase Smurf-mediated degradation. The extent of the acetylation is up-regulated by the transforming growth factor-beta signaling pathway and down-regulated by histone deacetylase activities. Our findings demonstrate that the level of RUNX3 protein is controlled by the competitive acetylation and deacetylation of the three lysine residues, revealing a new mechanism for the posttranslational regulation of RUNX3 expression.

Tumor suppressor activity of RUNX3

Recent analyses have revealed that RUNX family members play important roles in both normal developmental processes and carcinogenesis. Of the three known RUNX family members, RUNX3 has been shown to be involved in neurogenesis of the dorsal root ganglia, T-cell differentiation and tumorigenesis of gastric epithelium. Deletion of the Runx3 locus in mice resulted in hyperplasia of the gastric epithelium due to the stimulation of proliferation and suppression of apoptosis that was accompanied by a reduced sensitivity to TGF-beta1. In primary human gastric cancer specimens, RUNX3 is frequently inactivated by allele loss or gene silencing due to promoter hypermethylation. The tumorigenicity of human gastric cancer cell lines in nude mice decreased as the level of RUNX3 expression increased, which indicates that RUNX3 is a bona fide tumor suppressor of gastric cancers.