Virulence profile and genetic structure of a North Dakota population of Pyrenophora teres f. teres, the causal agent of net form net blotch of barley

A Pyrenophora teres f. teres population in North Dakota was analyzed for virulence variation and genetic diversity using 75 monospore isolates that were collected across a 4-year period (2004 to 2007) from two North Dakota State University agricultural experiment stations at Fargo and Langdon. Pathogenicity tests by inoculation onto 22 barley differential lines at seedling stage revealed 49 pathotypes, indicating a wide range of pathogenic diversity. Two-way analysis of variance of disease ratings revealed a significant difference in the virulence among isolates and in the resistance among barley lines, as well as in the interactions between the two. 'CI5791', 'Algerian', and 'Heartland' were three barley lines showing a high level of seedling resistance to all North Dakota isolates tested; however, many previously reported resistance genes have been overcome. Forty multilocus genotypes were identified from this set of isolates by genotyping at 13 simple-sequence repeat loci. High percentages of clonal cultures were detected in the samplings from 2005 and 2007 in Fargo and 2005 in Langdon. Using a clone-corrected sample set, the mean gene diversity (h) was estimated to be 0.58, approximately the same for both locations. The calculated Wright's F(ST) value is small (0.11) but was significantly >0, indicating a significant differentiation between the Fargo and Langdon populations. In the gametic disequilibrium test, only 3 of 78 possible pairwise comparisons over all isolates showed significant (P < 0.05) nonrandom association, suggesting a random mating mode. Our results suggest that the populations from the two locations are derived from a common source and undergo frequent recombination. This research provides important information for barley breeders regarding development and deployment of cultivars with resistance to net form net blotch in this region.

P5-13-14: Drug-Metabolizing Enzyme Polymorphisms and Clinical Outcome of Anthracycline-Based Chemotherapy in Chinese Han Breast Cancer Patients

Background

Anthracycline is one of the most effective drugs in the treatment of breast cancer and many of our most effective treatment regimens include anthracycline. Its efficacy can be influenced by cellular detoxification mechanisms involving drug metabolism and transport pathways. This study aimed to assess whether the functional polymorphisms in drug-metabolizing enzymes (MnSOD, CAT and GSTs) and transporter MDR1 may predict anthracycline treatment-related outcomes in Chinese Han breast cancer patients.

Material and methods: Genotyping was performed by allele-specific oligonucleotide ligation reaction (MnSOD T47C, CAT C-262T, GSTP1 A313G), multiplex PCR (GSTM1 null, GSTT1 null), and PCR-RFLP (MDR1 C3435T, G2677T/A and C1236T). Based on 153 evaluable patients received anthracycline-based neoadjuvant chemotherapy for breast cancer, the associations of these genotypes or their haplotypes with clinical response and recurrence-free survival (RFS) were analyzed.

Results: Of the 153 cases, the patients with GSTP1 313AA genotype had inferior response rates relative to those with AG or GG genotype (58.4% vs 77.8% or 100.0%; χ2=4.922, P=0.027). Moreover, the response rate of the combination of GSTP1 AA with both GSTT1 present and GSTM1 present was 44%, which was also lower comparing with the other groups (70.3%; χ2=6.454, P=0.011). A similar result was noticed for MDR1 3435 TT genotype, which had a significantly worse chemotherapy response compared with wild-type C allele carrier (33.3% vs 71.2%; χ2=11.586, P=0.001). Further, the response rate of the patients with 3435T-2677T, 3435T-1236T or 3435T-2677T-1236T haplotypes was lower than that of the patients with the other corresponding haplotypes (P=0.018, 0.011 and 0.019, respectively), too. Of note, the patients with both the adverse genotypes of GSTP1 314AA and MDR 3435TT shown the worst treatment efficacy in all (14.3%;χ2=26.33, P=0.000). Mean follow-up time of the 149 patients (4 patients lost) was 51 months. The recurrence rate in the patients with GSTP1 313AA or/and MDR 3435TT in the first three years was 39.0% (41/105), higher significantly than those with no adverse genotype [15.9% (7/44); OR=0.725, 95%Cl: 0.594−0.885, P=0.006]. Kaplan-Meier survival analysis showed that the patients with no adverse genotype were associated with reduced hazard of relapse (long-rank test, P&lt;0.01), compared to those with 1 or 2 adverse genotypes.

Conclusion: Polymorphisms in GSTs and MDR1 genes may help to predict clinical response and RFS of anthracycline-based chemotherapy in breast cancer, but further validation is required. These results provide support for a polygenic pathway approach for assessing the predictive potential of polymorphisms in treatment outcomes.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-13-14.

Complement inhibition enables renal allograft accommodation and long-term engraftment in presensitized nonhuman primates

Protection against humoral injury mediated by donor-specific antibodies (DSA), also known as accommodation, may allow for long-term allograft survival in presensitized recipients. In the present study, we determined the role of complement in renal allograft accommodation in donor skin-presensitized nonhuman primates under conventional immunosuppression. Donor skin allografts were transplanted to presensitized recipients 14 days prior to renal transplantation. Renal allografts not receiving any immunosuppressive treatment developed accelerated rejection with predominantly humoral injury, which was not prevented using conventional cyclosporine (CsA) triple therapy. Inhibition of complement activation with the Yunnan-cobra venom factor (Y-CVF) successfully prevented accelerated antibody-mediated rejection and resulted in successful accommodation and long-term renal allograft survival in most presensitized recipients. Accommodation in this model was associated with the prevention of the early antibody responses induced against donor antigens by complement inhibition. Some antiapoptotic proteins and complement regulatory proteins, including Bcl-2, CD59, CD46 and clusterin, were upregulated in the surviving renal allografts. These results suggest that the complement inhibition-based strategy may be valuable alternative in future clinical cross-match positive or ABO-incompatible transplantation.

Sequence variation and genetic diversity in the giant panda

About 336-444 bp mitochondrial D-loop region and tRNA gene were sequenced for 40 individuals of the giant panda which were collected from Mabian, Meigu, Yuexi, Baoxing, Pingwu, Qingchuan, Nanping and Baishuijiang, respectively. 9 haplotypes were found in 21 founders. The results showed that the giant panda has low genetic variations, and that there is no notable genetic isolation among geographical populations. The ancestor of the living giant panda population perhaps appeared in the late Pleistocene, and unfortunately, might have suffered bottleneck attacks. Afterwards, its genetic diversity seemed to recover to some extent.

Climatology of persistent deep stable layers in Utah's Salt Lake Valley, USA

Abstract. The characteristics of winter season persistent deep stable layers (PDSLs) over Utah's Salt Lake Valley are examined using 30-year twice daily rawinsonde soundings. The results highlight the basic climatological characteristics of the PDSLs, including the strengths of the inversion, the frequency of the occurrence, and the duration of the events. The data analyses also reveal linear trend, interannual variability, as well as the relationship between the interannual variability of PDSLs and the variability of large-scale circulations. Finally, the study investigates the large-scale atmosphere conditions accompanying the formation and destruction of the PDSL episodes.

CHARMM general force field: A force field for drug-like molecules compatible with the CHARMM all-atom additive biological force fields

The widely used CHARMM additive all-atom force field includes parameters for proteins, nucleic acids, lipids, and carbohydrates. In the present article, an extension of the CHARMM force field to drug-like molecules is presented. The resulting CHARMM General Force Field (CGenFF) covers a wide range of chemical groups present in biomolecules and drug-like molecules, including a large number of heterocyclic scaffolds. The parametrization philosophy behind the force field focuses on quality at the expense of transferability, with the implementation concentrating on an extensible force field. Statistics related to the quality of the parametrization with a focus on experimental validation are presented. Additionally, the parametrization procedure, described fully in the present article in the context of the model systems, pyrrolidine, and 3-phenoxymethylpyrrolidine will allow users to readily extend the force field to chemical groups that are not explicitly covered in the force field as well as add functional groups to and link together molecules already available in the force field. CGenFF thus makes it possible to perform "all-CHARMM" simulations on drug-target interactions thereby extending the utility of CHARMM force fields to medicinally relevant systems.

A one-year investigation of the relationship between serum GH levels and the growth of F(4) transgenic and non-transgenic common carp Cyprinus carpio

It has been demonstrated that growth hormone (GH) transgenic fish often posses a trait for fast growth. Here, we investigated the growth of F(4)'all-fish' GH transgenic carp Cyprinus carpio and their serum GH levels for a year. The results showed that F(4) all-fish GH transgenic carp were significantly larger in body mass (c. two-fold, P < 0.001) and body length (c. 1.3 fold, P < 0.001), compared with the non-transgenic group. The discrepancy of serum GH levels between the transgenic carp group and control group is 54 fold, when the water temperature was 12-34 degrees C. When the water temperature decreased to 3.5 degrees C in January, the discrepancy was 256 fold. The serum GH level of the transgenic group was relatively constant, while that of control varied greatly based on month and water temperature. The changes of growth rates between the transgenic group and the control group were similar for a year. Taken together, the results indicated that F(4) all-fish GH transgenic carp had not only higher and constant serum GH levels but also a significant fast-growing effect, compared with the control. To our knowledge, this is the first report on a one-year investigation of growth trait and serum growth hormone level in F(4) all-fish GH transgenic carp.

TS and MTHFR gene polymorphisms in patients (pts) with recurrent or metastatic squamous cell carcinoma of the head or neck (SCCHN) treated with pemetrexed (P) and bevacizumab (B)

e17011

Background: P inhibits multiple enzymes in folate metabolism. We examined polymorphisms in thymidylate synthase (TS) and methylenetetrahydrofolate reductase (MTHFR) in patients with SCCHN treated in a phase II clinical trial with P and B (ASCO 2008; A6069). Methods: All pts were treated with P 500 mg/m2 and B 15 mg/kg, given IV every 21 days until progression. Primary endpoint was time to progression (TTP). DNA was isolated from whole blood samples using commercially available kits. Polymorphisms examined were MTHFR (C677T, A1298C and G1793A) and TS (TS2R3R, TSG2RG and TSmut6). The MTHFR SNPs were detected using TaqMan based SNP genotyping kits from Applied Biosystems, run on the ABI Prism 7700 Sequence Detection systems v 1.7 (Foster City, CA). The TS promoter repeat and promoter SNP polymorphisms and the 3’ untranslated region 6 bp deletion polymorphism were determined using published methods to detect PCR product size and RFLP-PCR assays respectively. Results: 22 pts were genotyped from 34 enrolled. There was no significant difference in characteristics between pts with and without genotype data. For the MTHFR polymorphism C677T, there was a trend towards decreased disease control rate (DCR) (CR/PR/SD) (p = 0.058, Jonckheere-Terpstra trend test) and worse TTP (p = 0.04) transitioning from variant CC to CT to TT; comparing TT genotype versus CT and CC combined, pts with TT had inferior DCR (p = 0.03) and TTP (p = 0.0003); homozygotes with TT had a median TTP of 2.6 months (mo) 95% CI (1.4, NA) versus 5.6 mo (4.2, 11.4) for pts with CT or CC variants. For the MTHFR A1298C SNP, there was no significant difference in DCR between variants, median TTP for homozygotes pts with AA was 4.1 mo (2.6, NA) vs. 6.7 mo (5.1, NA) in pts with AC or CC variants (p = 0.084); median overall survival for AA was 10.2 mo (7.6, NA) and for AC or CC 17.6 mo (17, NA) (p = 0.045). The MTHFR G1793A and TS polymorphisms did not impact DCR, TTP or overall survival. There was no association between any polymorphism and the incidence of grade >2 toxicities. Conclusions: Polymorphisms in MTHFR are potentially associated with antitumor efficacy of P-based therapy in recurrent or metastatic SCCHN. These results warrant validation in larger studies with P in SCCHN.

No significant financial relationships to disclose.

Development and characterization of expressed sequence tag-derived microsatellite markers for the wheat stem rust fungus Puccinia graminis f. sp. tritici

Puccinia graminis f. sp. tritici is the causal agent of stem rust disease in wheat. The rust fungus has caused devastating disease epidemics throughout history and is still posing a potential threat to wheat production in some regions of the world due to the appearance of new races. To develop microsatellite or simple sequence repeat (SSR) markers for use in population genetics studies, a total of 60,579 expressed sequence tag (EST) sequences (reads) generated from P. graminis f. sp. tritici were screened for tandemly repeated di- and tri-nucleotide units using a bioinformatics approach and 708 unisequences containing putative SSR loci with six or more repeat units were identified. Flanking primers were designed for 384 unique SSR loci, which mapped to different locations of the draft genome sequence of the fungus. Of the 384 primer pairs tested, 72 EST-SSR markers were eventually developed, which showed polymorphism among 19 isolates of P. graminis f. sp. tritici and 4 isolates of P. graminis f. sp. secalis evaluated. Thirty-two of the SSR loci were also evaluated in three other rust fungi (P. triticina, P. hordei, and P. coronata f. sp. hordei) for cross-species transferability. These SSR markers derived from ESTs will be useful for characterization of population structures and for gene mapping in P. graminis.

Even distribution of BK polyomavirus subtypes and subgroups in the Japanese Archipelago

BK polyomavirus (BKV) is ubiquitous among humans, infecting children asymptomatically and then persisting in renal tissue. BKV has four subtypes (I-IV) that can be identified by serological and genotyping methods. Subtypes I and IV are most prevalent in all countries examined to date. Based on nucleotide sequence variation, subtype I is further classified into four subgroups (Ia, Ib-1, Ib-2 and Ic), each of which have a close relationship to a particular human population. To clarify the relationships between BKV and human populations, we investigated the distribution patterns of BKV subtypes and subgroups in the modern Japanese population, which was formed from two distinct ethnic groups. Urine samples were collected from immunocompetent elderly patients in six regions along the Japanese Archipelago. The 287-bp VP1 region of the viral genome from these samples was amplified using the polymerase chain reaction. The amplified VP1 regions were sequenced and a neighbor-joining phylogenetic tree was reconstructed to classify the BKV isolates. We observed a similar pattern of subtype distribution throughout the Japanese Archipelago, with subtype I always detected at high rates (67-75%), followed by subtype IV (19-31%), with rare or no detection of subtypes II and III. Based on phylogenetic and single nucleotide polymorphism analyses, the subtype I isolates were divided into subgroups; the percentage of the Ic subgroup was high in all geographic regions (88-100%). These results suggest that BKV subtypes and subgroups are evenly distributed in the Japanese Archipelago. We discuss the implications of these findings for the relationships between BKV and human populations.

Pharmacologic inhibition of epigenetic modifications, coupled with gene expression profiling, reveals novel targets of aberrant DNA methylation and histone deacetylation in lung cancer

Lung cancer is the leading cause of cancer-related deaths in the United States due, in large part, to the lack of early detection methods. Lung cancer arises from a complex series of genetic and epigenetic changes leading to uncontrolled cell growth and metastasis. Unlike genetic changes, epigenetic changes, such as DNA methylation and histone acetylation, are reversible with currently available pharmaceuticals and are early events in lung tumorigenesis detectable by non-invasive methods. In order to better understand how epigenetic changes contribute to lung cancer, and to identify new disease biomarkers, we combined pharmacologic inhibition of DNA methylation and histone deacetylation in non-small cell lung cancer (NSCLC) cell lines, with genome-wide expression profiling. Of the more than 200 genes upregulated by these treatments, three of these, neuronatin, metallothionein 3 and cystatin E/M, were frequently hypermethylated and transcriptionally downregulated in NSCLC cell lines and tumors. Interestingly, four other genes, cylindromatosis, CD9, activating transcription factor 3 and oxytocin receptor, were dominantly regulated by histone deacetylation and were also frequently downregulated in lung tumors. The majority of these genes also suppressed NSCLC growth in culture when ectopically expressed. This study therefore reveals new putative NSCLC growth regulatory genes and epigenetic disease biomarkers that may enhance early detection strategies and serve as therapeutic targets.

Subtype IV of the BK polyomavirus is prevalent in East Asia

BK polyomavirus (BKV) is ubiquitous in human populations, infecting children asymptomatically and then persisting in the kidney. Using either serological or genotyping methods, BKV isolates have been classified into four subtypes (I-IV), with subtype I mainly detected in all countries studied so far. To elucidate the subtype of BKV prevalent in East Asia, we examined BKV-positive urine samples collected from immunocompetent elderly patients in Mongolia, Northeast China, Northwest China, Southeast China, Southwest China, Vietnam and Japan. The 287-bp typing region of the viral genome in each of these samples was PCR-amplified and sequenced, and a phylogenetic tree was constructed. According to the tree, BKV isolates in East Asia were unambiguously classified into subtype I or IV (subtypes II and III were not detected). In Japan, subtype I was mainly detected and subtype IV was rare, whereas in the other regions subtype IV was detected frequently, at rates ranging from 24 to 100%. Thus, East Asia (excluding Japan) is a region in which subtype-IV BKV is prevalent, a finding that requires the view of the geographic distribution of BKV subtypes to be revised. Furthermore, we present evidence that the immunological states of urine donors do not affect the pattern of BKV subtypes.

First Report of a Rust Disease on Ohia Caused by Puccinia psidii in Hawaii

Several species of Metrosideros (Myrtaceae), referred to as ohia in Hawaii, are endemic trees that comprise as much as 80% of the native Hawaiian forests. For centuries, these trees have provided niches for many indigenous and endangered plants and animals and are treasured by Hawaiians for their beauty and role in folklore and legends. During April 2005, a cultivated ohia plant was diagnosed by the Agricultural Diagnostic Service Center at the University of Hawaii at Manoa as infected by a rust fungus. Rust pustules containing abundant urediniospores were observed on leaves, stems, and sepals, causing discolored spots and severe deformity of young leaves and growing tips. By July 2005, a similar rust disease was observed on other plants in the family Myrtaceae; namely Syzygium jambos (L.) Alston, Eugenia koolauensis Degener, E. reinwardtiana (Blume) DC, and Psidium guajava L. Microscopic examination of the uredinia and urediniospores showed that the rust was morphologically similar to Puccinia psidii, which is reported as the guava or eucalyptus rust in Florida and Central and South America (1,2). To confirm the identity of this fungus, DNA was extracted from urediniospores of two isolates collected from ohia plants, and their nuclear ribosomal internal transcribed spacer (ITS) was amplified with two universal primers, ITS4 and ITS5 (3). Sequences of the ITS region of these isolates from ohia were identical to the P. psidii isolates provided by A. Alfenas in Brazil and M. Rayachhetry in Florida. Koch's postulate of the isolates, obtained from ohia, was performed using 1 × 10⁸ spores/ml of urediniospores suspension in distilled water. The suspension was sprayed onto 6-month-old ohia seedlings. These inoculated seedlings were placed in clear plastic chambers maintained at 100% relative humidity and 22°C with a combination of 10-h fluorescent light period and a 14-h dark period. After 48 h of incubation, the seedlings were removed from the chambers and transferred to a greenhouse where the ambient temperature ranged from 20 to 24°C. Rust pustules appeared after 1 to 2 weeks of incubation. Symptoms first appeared as tiny, bright yellow, powdery eruptions that developed into circular, uredinial pustules on the stem and foliage. These pustules later expanded, coalesced, and became necrotic, spreading over the entire leaf and stem surfaces, and then leaves and stems were deformed and tip dieback ensued. These symptoms were the same as those observed on the naturally infected cultivated ohia plant mentioned above. P. psidii is reported to be native to South and Central America that later spread to some Myrtaceous plants in the Caribbean countries (1). It has a very wide host range within the family Myrtaceae (2). To our knowledge, this is the first report of P. psidii in Hawaii. This rust disease may pose a formidable threat to Myrtaceous species that make up the native Hawaiian forests and are grown as ornamental plants or for the production of wood chips. References: (1) T. A. Coutinho et al. Plant Dis. 82:819. 1998. (2) M. B. Rayachhetry et al. Biol. Control 22:38. 2001. (3) T. J. White et al. Page 315 in: PCR Protocols. M. A. Innis et al., eds. 1990.

Comprehensive analysis of risk factors associating with Hepatitis B virus (HBV) reactivation in cancer patients undergoing cytotoxic chemotherapy

For cancer patients with chronic hepatitis B virus (HBV) infection, who receive cytotoxic chemotherapy, HBV reactivation is a well-described complication, which may result in varying degrees of liver damage. Several clinical features and the pre-chemotherapy HBV viral load have been suggested to be associated with an increased risk of developing the condition: (1) to assess the clinical and virological factors in a comprehensive manner and thereby identify those that are associated with the development of HBV reactivation; (2) to develop a predictive model to quantify the risk of HBV reactivation. In all, 138 consecutive cancer patients who were HBV carriers and undergoing chemotherapy were studied, of which 128 patients had sera available for real-time PCR HBV DNA measurement. They were followed up throughout their course of chemotherapy and the HBV reactivation rate was determined. The clinical and virological features between those who did and did not develop viral reactivation were compared. These included age, sex, baseline liver function tests, HBeAg status and viral load (HBV DNA) prior to the chemotherapy, and the use of specific cytotoxic agents. In all, 36 (26%) developed HBV reactivation. Multivariate analysis revealed pre-chemotherapy HBV DNA level, the use of steroids and a diagnosis of lymphoma or breast cancer to be significant factors. Based on real-time HBV DNA PCR assay, detectable baseline HBV DNA prior to the administration of cytotoxic chemotherapy, the use of steroids and a diagnosis of lymphoma or breast cancer are predictive factors for the development of HBV reactivation. A predictive model was developed from the current data, based on a logistic regression method.

High hepatitis B virus (HBV) DNA viral load is an important risk factor for HBV reactivation in breast cancer patients undergoing cytotoxic chemotherapy

Hepatitis B virus (HBV) reactivation during cytotoxic chemotherapy for cancer may complicate treatment and cause liver damage. The complication has been reported to occur in 10% to over 50% of HBV carriers, but the factors that determine which patients will develop reactivation remain unclear. The objective of the study is to test the hypothesis that the prechemotherapy HBV DNA level is a risk factor for the development of HBV reactivation. We studied 41 women undergoing cytotoxic chemotherapy for breast cancer, 17 of whom developed reactivation and 24 who did not. We developed a novel, ultra-sensitive, real-time polymerase chain reaction assay for the measurement of HBV DNA. The sera of 37 patients (16 who developed reactivation and 21 who did not) were available for measurement of HBV DNA using this technique. The results showed that patients in the reactivation group had a significantly higher median HBV DNA load (1.03 x 10(6) copies/mL; range <2.9 x 10(3) to 8.723 x 10(7)) than did the nonreactivation group (<2.9 x 10(3) copies/ml; range <2.9 x 10(3) to 6.331 x 10(7)) (P < 0.001). The optimal cut-off between the two groups was found to be at serum HBV DNA level of 3 x 10(5), which gave a sensitivity of 81.0% and a specificity of 85.0%. In conclusion, for breast cancer patients receiving standard cytotoxic chemotherapy, a high HBV viral load prior to the administration of cytotoxic chemotherapy is a significant predictive factor for the development of HBV reactivation. Such information may be useful in determining which patients would benefit most from prophylactic antiviral therapy during cytotoxic chemotherapy.

The biological response of MCF7 breast cancer cells to proteosome inhibition or gamma-radiation is unrelated to the level of p53 induction

The p53 tumour suppressor is stabilised following exposure to genotoxic agents, such as gamma-radiation. Cell responses to p53 stabilisation include induction of apoptosis and/or cell cycle arrest. Several studies have suggested that gamma-radiation stabilises p53 by blocking ubiquitin mediated proteolysis. Here we have compared the biological activities of p53 stabilized following exposure to gamma-radiation or treatment with the proteosome inhibitor N-acetyl-leucinyl-leucinyl-norleucinal (ALLN) in MCF7 cells with wild type p53. Stabilisation of p53 by ALLN was reversible and was not blocked by caffeine. Although ALLN was a more effective p53 stabilising agent than gamma-radiation, ALLN was not as effective at inducing cell cycle arrest/apoptosis as gamma-radiation. Although p53 stabilised by ALLN and gamma-radiation were both able to bind DNA and activate transcription, ALLN did not increase expression of BAX, which is involved in p53-induced apoptosis. Therefore, p53 stabilised by different agents is not always biologically active to the same extent and additional alterations triggered by gamma-radiation may enable p53 to activate a subset of critical target genes, such as BAX, which are required for p53 responses.

Fabrication and properties of spray-dried nanofeatured spherical Ni(OH)2 materials

Spherical agglomerates of nanostructured beta-phase Ni(OH)2 with the general formula Ni1-xCox(OH)2 (x = 0, 0.1, 0.3) for use as cathode materials were produced by a modified method including coprecipitation of Ni or Ni composite hydroxide and further spray drying of the precipitated and washed slurry. This process leads to the formation of spherical agglomerate particles with a narrow Gaussian-type distribution range. The method permits faster and cheaper production of cathode materials with a higher specific surface area and similar or better capacity and cycle life compared with the materials prepared via conventional technology.

Identification and characterization of DNA markers associated with a locus conferring virulence on barley in the plant pathogenic fungus Cochliobolus sativus

Cochliobolus sativus is a plant pathogenic fungus that causes spot blotch on barley and wheat. Virulence of a pathotype-2 isolate (ND90Pr) on barley cultivar Bowman was previously determined to be controlled by a single locus. To identify DNA markers associated with this virulence locus, amplified fragment length polymorphism (AFLP) analysis was conducted on 104 progeny isolates derived from a cross between isolates ND90Pr (exhibiting high virulence on Bowman) and ND93-1 (exhibiting low virulence on Bowman). Among 115 AFLP markers identified, 14 were linked to the virulence locus VHv1 in isolate ND90Pr, six of which co-segregated with VHv1. Two (E-AG/M-CA-207 and E-AG/M-CG-121) of the six co-segregating AFLP markers were cloned and used to probe genomic DNAs from the fungal parents and progeny. Both markers hybridized only with DNAs from ND90Pr and the virulent progeny. These two cloned markers were also used as probes to survey field isolates of C. sativus collected from different regions of the world and again only hybridized to DNAs from isolates that had the same virulence phenotype as ND90Pr. The results of this study indicate that E-AG/M-CA-207 and E-AG/M-CG-121 are closely linked to VHv1 and are unique to isolates carrying the virulence locus. Development of a linkage group, coupled with the identification of closely linked molecular markers, will facilitate the cloning of the virulence gene VHv1 in C. sativus by map-based cloning.

Effects of long-term enalapril and losartan therapy of hypertension on cardiovascular aldosterone

BACKGROUND

Plasma aldosterone escape is found during long-term angiotensin-converting enzyme inhibitor therapy. Evidence for aldosterone production in cardiovascular tissues raised the question of whether or not aldosterone escape occurs in these tissues.

METHOD

Spontaneously hypertensive rats were treated with enalapril (20 mg/kg/day) and losartan (50 mg/kg/day) for 20 weeks; untreated spontaneously hypertensive and Wistar rats were used as positive and normal controls, respectively. Ex vivo mesenteric artery and heart perfusion, high-performance liquid chromatography, and radioimmunoassay for aldosterone were performed.

RESULTS

The results showed that enalapril failed to significantly inhibit aldosterone production in mesenteric artery, myocardium and plasma. Losartan significantly inhibited aldosterone production to that of Wistar rats in the mesenteric artery, myocardium and plasma.

CONCLUSION

This study provides the first evidence that long-term angiotensin-converting enzyme inhibition therapy induces aldosterone escape in hypertensive cardiovascular tissues, and angiotensin II subtype 1 receptor antagonist does not induce aldosterone escape in mesenteric artery, myocardium and plasma of spontaneously hypertensive rats.

Optical tomographic imaging of dynamic features of dense-scattering media

Methods used in optical tomography have thus far proven to produce images of complex target media (e.g., tissue) having, at best, relatively modest spatial resolution. This presents a challenge in differentiating artifact from true features. Further complicating such efforts is the expectation that the optical properties of tissue for any individual are largely unknown and are likely to be quite variable due to the occurrence of natural vascular rhythms whose amplitudes are sensitive to a host of autonomic stimuli that are easily induced. We recognize, however, that rather than frustrating efforts to validate the accuracy of image features, the time-varying properties of the vasculature can be exploited to aid in such efforts, owing to the known structure-dependent frequency response of the vasculature and to the fact that hemoglobin is a principal contrast feature of the vasculature at near-infrared wavelengths. To accomplish this, it is necessary to generate a time series of image data. In this report we have tested the hypothesis that through analysis of time-series data, independent contrast features can be derived that serve to validate, at least qualitatively, the accuracy of imaging data, in effect establishing a self-referencing scheme. A significant finding is the observation that analysis of such data can produce high-contrast images that reveal features that are mainly obscured in individual image frames or in time-averaged image data. Given the central role of hemoglobin in tissue function, this finding suggests that a wealth of new features associated with vascular dynamics can be identified from the analysis of time-series image data.

PML-RARalpha alleviates the transcriptional repression mediated by tumor suppressor Rb

A fusion between the promyelocytic leukemia (PML) protein and the retinoic acid receptor-alpha (RARalpha) results in the transforming protein of acute promyelocytic leukemia, PML-RARalpha. PML has growth-suppressive properties and is localized within distinct nuclear structures referred to as nuclear bodies. PML participates in numerous cellular functions, including transcriptional activation, apoptosis, and transcriptional repression, whereas PML-RARalpha blocks these functions. However, the role played by PML-RARalpha in leukemogenesis remains unclear. Here we report that PML is required for transcriptional repression mediated by the tumor suppressor Rb. Rb interacts with the histone decaetylase (HDAC) complex containing co-repressors and represses the transcription of the E2F target genes. Overexpression of PML enhanced Rb-mediated repression. The degree of Rb-mediated repression was weakened by injecting anti-PML antibodies and was lower in Pml-deficient mouse embryonic fibroblasts. PML-RARalpha inhibited Rb-mediated repression, and two co-repressor-interacting sites on the PML-RARalpha molecule were required for this activity. Furthermore, PML-RARalpha blocked the interaction between Rb and HDAC. Thus, aberrant binding of PML-RARalpha to co-repressor-HDAC complexes may inhibit their association with Rb, resulting in the abrogation of Rb activity. Thus, the disruption of Rb-mediated repression may be a contributory factor in leukemogenesis.

Histone deacetylase inhibitors induce remission in transgenic models of therapy-resistant acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is associated with chromosomal translocations, invariably involving the retinoic acid receptor alpha (RAR alpha) gene fused to one of several distinct loci, including the PML or PLZF genes, involved in t(15;17) or t(11;17), respectively. Patients with t(15;17) APL respond well to retinoic acid (RA) and other treatments, whereas those with t(11;17) APL do not. The PML-RAR alpha and PLZF-RAR alpha fusion oncoproteins function as aberrant transcriptional repressors, in part by recruiting nuclear receptor-transcriptional corepressors and histone deacetylases (HDACs). Transgenic mice harboring the RAR alpha fusion genes develop forms of leukemia that faithfully recapitulate both the clinical features and the response to RA observed in humans with the corresponding translocations. Here, we investigated the effects of HDAC inhibitors (HDACIs) in vitro and in these animal models. In cells from PLZF-RAR alpha/RAR alpha-PLZF transgenic mice and cells harboring t(15;17), HDACIs induced apoptosis and dramatic growth inhibition, effects that could be potentiated by RA. HDACIs also increased RA-induced differentiation. HDACIs, but not RA, induced accumulation of acetylated histones. Using microarray analysis, we identified genes induced by RA, HDACIs, or both together. In combination with RA, all HDACIs tested overcame the transcriptional repression exerted by the RAR alpha fusion oncoproteins. In vivo, HDACIs induced accumulation of acetylated histones in target organs. Strikingly, this combination of agents induced leukemia remission and prolonged survival, without apparent toxic side effects.

ASPP proteins specifically stimulate the apoptotic function of p53

We identified a family of proteins termed ASPP. ASPP1 is a protein homologous to 53BP2, the C-terminal half of ASPP2. ASPP proteins interact with p53 and specifically enhance p53-induced apoptosis but not cell cycle arrest. Inhibition of endogenous ASPP function suppresses the apoptotic function of endogenous p53 in response to apoptotic stimuli. ASPP enhance the DNA binding and transactivation function of p53 on the promoters of proapoptotic genes in vivo. Two tumor-derived p53 mutants with reduced apoptotic function were defective in cooperating with ASPP in apoptosis induction. The expression of ASPP is frequently downregulated in human breast carcinomas expressing wild-type p53 but not mutant p53. Therefore, ASPP regulate the tumor suppression function of p53 in vivo.

Gross elevation of TT virus genome load in the peripheral blood mononuclear cells of cancer patients

TT virus (TTV) is a recently described circular DNA virus of about 3.8 kb, which is related to the circoviridae viruses. It is commonly detected in healthy subjects and no association with any specific disease has been established. TTV was initially thought to be hepatotropic, but subsequent reports have shown that it is detectable in other tissues, including kidney, prostate, mammary gland, brain, bone marrow, and peripheral blood mononuclear cells. Plasma samples from cancer patients and healthy subjects were tested for the presence or absence of TTV by heminested polymerase chain reaction (PCR). We also developed a quantitative competitive PCR (QC-PCR) assay for TTV that permits accurate measurement of TTV DNA load. Using this assay, the TTV genome load in peripheral blood mononuclear cells (PBMCs) of healthy control subjects (n = 50) and patients with various types of cancer (n = 148), including breast cancer, non-Hodgkin's lymphoma, colon cancer, hepatocellular carcinoma, nasopharyngeal carcinoma, and other cancers, was measured. TTV DNA was detected in 69 of 100 plasma samples (69%) of cancer patients tested and in 39 of 100 plasma samples (39%) randomly selected from 1000 plasma samples of blood donors (p < 0.05). TTV DNA was detectable in the PBMCs of 99% of the cancer patients and 86% of the controls. However, the median virus load was more than 100-fold higher in the cancer patients (3599 copies/100,000 cells) than among the controls (30 copies/100,000 cells; p < 0.0001). There was no significant difference in TTV load among the different cancer types. Using a cutoff value of >250 copies per 100,000 PBMCs, 93.2% of cancer patients were "positive" compared to only 4% of healthy control subjects. Almost all the cancer patients have TTV infection and their TTV genome load in PBMCs is significantly higher than that in control subjects. It remains to be elucidated whether such findings are specific to cancer patients or occur in all seriously ill subjects.

Ultraviolet B-induced phosphorylation of histone H3 at serine 28 is mediated by MSK1

N-terminal tail phosphorylation of histone H3 plays an important role in gene expression, chromatin remodeling, and chromosome condensation. Phosphorylation of histone H3 at serine 10 was shown to be mediated by RSK2, mitogen- and stress-activated protein kinase-1 (MSK1), and mitogen-activated protein kinases depending on the specific stimulation or stress. Our previous study showed that mitogen-activated protein kinases MAP kinases are involved in ultraviolet B-induced phosphorylation of histone H3 at serine 28 (Zhong, S., Zhong, Z., Jansen, J., Goto, H., Inagaki, M., and Dong, Z., J. Biol. Chem. 276, 12932-12937). However, downstream effectors of MAP kinases remain to be identified. Here, we report that H89, a selective inhibitor of the nucleosomal response, totally inhibits ultraviolet B-induced phosphorylation of histone H3 at serine 28. H89 blocks MSK1 activity but does not inhibit ultraviolet B-induced activation of MAP kinases p70/85(S6K), p90(RSK), Akt, and protein kinase A. Furthermore, MSK1 markedly phosphorylated serine 28 of histone H3 and chromatin in vitro. Transfection experiments showed that an N-terminal mutant MSK1 or a C-terminal mutant MSK1 markedly blocked MSK1 activity. Compared with wild-type MSK1, cells transfected with N-terminal or C-terminal mutant MSK1 strongly blocked ultraviolet B-induced phosphorylation of histone H3 at serine 28 in vivo. These data illustrate that MSK1 mediates ultraviolet B-induced phosphorylation of histone H3 at serine 28.

Host marrow stem cell potential and engraftability at varying times after low-dose whole-body irradiation

High levels of chimerism in syngeneic BALB/c transplants were reported when hosts were exposed to 1 Gy (100 cGy) whole body irradiation (WBI) and infused with 40 x 10(6) marrow cells. The recovery of host stem cells and alterations of enhanced host engraftability at varying times after 1 Gy WBI have now been evaluated in this study. Male BALB/c marrow (40 x 10(6) cells) was infused into female BALB/c hosts immediately or at 6, 12, and 24 weeks after 1 Gy WBI of host female BALB/c mice; engraftment percentages 8 weeks after cell injection at week 0, 6, 12, or 24 were 68% +/- 12%, 45% +/- 15%, 51% +/- 12%, or 20% +/- 8%, respectively. Eight-week engraftment levels in nonirradiated hosts average 7.7%. Conversely, engraftable stem cells measured at 8 weeks postengraftment in 1 Gy--exposed hosts were reduced to 8.6% +/- 3% of nonirradiated mice at time 0, 35% +/- 12% 6 weeks later, 49% +/- 10% at 3 months, and 21% +/- 7% at 6 months. Engraftment was still increased and stem cell decreased 1 year after 1 Gy. Furthermore, the primary cells transplanted into 1 Gy hosts can be serially transplanted, and the predominant effect of 1 Gy is directly on engrafting stem cells and not through accessory cells. These data show that transplantation in 1 Gy mice may be delayed until recovery of hematopoiesis, suggesting strategies in allogeneic transplantation to avoid the adverse effects of cytokine storm. The incomplete recovery of engraftable stem cells out to 12 months indicates that stem cell expansion, especially in patients previously treated with radiomimetic drugs, may not be feasible. (Blood. 2001;98:1246-1251)

[Significance of vascular endothelial growth factor expression in colorectal cancer]

OBJECTIVE

To investigate the expression of vascular endothelial growth factor (VEGF) mRNA in colorectal cancer (CRC) and its relation with the clinicopathologic features and explore new approaches to prevent and inhibit recurrence and metastasis of CRC.

METHODS

Surgical samples of 68 patients with CRC were studied using reverse transcription-polymerase chain reaction (RT-PCR). The relative level of VEGF mRNA expression was measured by determining a ratio of PCR products of VEGF to that of beta-actin gene.

RESULTS

(1) Expression of VEGF mRNA in tumor tissue was found in 67.6% (46/68) of the sample, whereas it was seen in 32.4% (22/68) of the surrounding nontumorous colorectal tissue. (2) The level of VEGF mRNA expression in tumors with serosal invasion, lymph node metastasis, distant metastasis or Dukes' D stage was higher than that without serosal invasion, lymph node metastasis, distant metastasis or Dukes' A and B and C stage (P < 0.01). (3) There was no significant difference in the expression of VEGF mRNA between large CRC (diameter > 5 cm) and small CRC (diameter < or = 5 cm) (P > 0.05) or histologic types (P > 0.05).

CONCLUSION

VEGF may play an important role in the invasion and metastasis of CRC. It is thus show that angiogenesis in tumor correlates with the progression of CRC.

Quantitative and genotypic analysis of TT virus infection in Chinese blood donors

BACKGROUND

The TT virus (TTV) is a member of a newly described family of human viruses related to the C ircoviridae viruses. Its association with specific diseases has not been established, and screening of blood donors has not been implemented. To date, 16 genotypes have been identified.

STUDY DESIGN AND METHODS

Sera from 471 healthy blood donors (aged 11-58 years) were randomly selected and tested for TTV by the use of two sets of primers: NG59d/NG61d/NG63d primers and T801/T935 primers. Quantitative competitive PCR (QC-PCR) was developed to measure the TTV DNA concentration among the blood donors. Sequencing of a part of the genome was performed to identify the various genotypes. Several samples showed a mixed genotype infection.

RESULTS

TTV was detected in 251 (53.3%) of 471 healthy Hong Kong blood donors by the use of NG59d/NG61d/NG63d primers. The prevalence of the virus increased steadily with age (p = 0.03). TTV DNA was detected in 90 percent (90 of a randomly selected 100) of samples by the use of T801/T935 primers. TTV DNA concentration was also measured by QC-PCR in the blood donors who were positive for TTV DNA in the first round of the heminested PCR. TTV titers ranged from 4.8 x 10(2) copies per mL to 6 x 10(4) copies per mL, with a median value of 1.2 x 10(4) copies per mL. Sequencing and phylogenetic analysis of a 223-bp fragment from open reading frame 1 showed three main genotypes (G1 [60.7%], G2 [24.3%], and G3 [14%]) and a new genotype 17 (G17), with the latter bearing 60-percent nucleotide homology with other genotypes deposited at GenBank. In addition, a new TTV subtype, G2f, was found.

CONCLUSION

The prevalence of TTV is high in healthy Chinese blood donors. Three main genotypes (G1, G2, and G3) were detected. In addition, a new TTV genotype, tentatively designated as G17, and a new subtype, G2f, were identified.

Signal transduction pathways involved in phosphorylation and activation of p70S6K following exposure to UVA irradiation

Ultraviolet light A (UVA) plays an important role in the etiology of human skin cancer, and UVA-induced signal transduction has a critical role in UVA-induced skin carcinogenesis. The upstream signaling pathways leading to p70(S6K) phosphorylation and activation are not well understood. Here, we observed that UVA induces phosphorylation and activation of p70(S6K). Further, UVA-stimulated p70(S6K) activity and phosphorylation at Thr(389) were blocked by wortmannin, rapamycin, PD98059, SB202190, and dominant negative mutants of phosphatidylinositol (PI) 3-kinase p85 subunit (DNM-Deltap85), ERK2 (DNM-ERK2), p38 kinase (DNM-p38), and JNK1 (DNM-JNK1) and were absent in Jnk1-/- or Jnk2-/- knockout cells. The p70(S6K) phosphorylation at Ser(411) and Thr(421)/Ser(424) was inhibited by rapamycin, PD98059, or DNM-ERK2 but not by wortmannin, SB202190, DNM-Deltap85, or DNM-p38. However, Ser(411), but not Thr(421)/Ser(424) phosphorylation, was suppressed in DNM-JNK1 and abrogated in Jnk1-/- or Jnk2-/- cells. In vitro assays indicated that Ser(411) on immunoprecipitated p70(S6K) proteins is phosphorylated by active JNKs and ERKs, but not p38 kinase, and Thr(421)/Ser(424) is phosphorylated by ERK1, but not ERK2, JNKs, or p38 kinase. Moreover, p70(S6K) co-immunoprecipitated with PI 3-kinase and possibly PDK1. The complex possibly possessed a partial basal level of phosphorylation, but not at MAPK sites, which was available for its activation by MAPKs in vitro. Thus, these results suggest that activation of MAPKs, like PI 3-kinase/mTOR, may be involved in UVA-induced phosphorylation and activation of p70(S6K).

Sympathetic nerve and cardiovascular responses to chemical activation of the midbrain defense region

The changes in mean arterial pressure (MAP), renal (RBF) and femoral (FBF) blood flows, and inferior cardiac (CN) and vertebral nerve (VN) sympathetic nerve discharges (SND) produced by chemical activation (d,l-homocysteic acid) of the midbrain periaqueductal gray (PAG) were compared in baroreceptor-denervated and -innervated cats anesthetized with urethan. Defenselike cardiovascular responses in both states were similar in magnitude and consisted of increased MAP and FBF and decreased RBF; however, the nerve responses differed. In baroreceptor-denervated cats, PAG activation increased CN 10-Hz activity, decreased VN 10-Hz activity, and lengthened the CN-VN phase angle. In baroreceptor-innervated cats in which the rhythm in SND was cardiac related, PAG activation increased CN activity, but VN activity and the CN-VN phase angle were unchanged. These results demonstrate that chemical activation of PAG neurons induces differential patterns of sympathetic outflow generally consistent with accompanying defenselike cardiovascular responses. However, the mechanisms responsible for the changes in 10-Hz and cardiac-related SND appear to be different.

Stem cell engraftment strategies

The donor stem cell phenotype and host microenvironment determine the outcome of a stem cell transplant. In a series of transplant studies in syngeneic male to female or congenic Ly5.1/Ly5.2 models in which hosts have received no or minimal irradiation (100 cGy), evidence overwhelmingly supports the concept that syngeneic engraftment is determined by stem cell competition. These approaches can be extended to H-2 mismatched allogeneic mouse combination when antigen pre-exposure and CD40-CD40 ligand antibody blockage are employed. A human trial in patients with resistant neoplasia infusing pheresed blood with 10(8) CD3 cells/kg showed that tumor responses and complete chimerism occur with very low levels of CD34+ cells/kg and that the extent of previous treatment is a critical factor in determining chimerism. A major feature of transplants is the phenotype of the donor stem cell. This phenotype shows dramatic reversible plasticity involving differentiation, adhesion protein expression, and engraftment with cytokine-induced cell-cycle transit. Homing is probably also plastic. Marked fluctuations in engraftment capacity are also seen at different points in marrow circadian rhythm.

Role of PML and PML-RARalpha in Mad-mediated transcriptional repression

Fusion of the promyelocytic leukemia (PML) protein to the retinoic acid receptor-alpha (RARalpha) generates the transforming protein of acute promyelocytic leukemias. PML appears to be involved in multiple functions, including apoptosis and transcriptional activation by RAR, whereas PML-RARalpha blocks these functions of PML. However, the mechanisms of leukemogenesis by PML-RARalpha remain elusive. Here we show that PML interacts with multiple corepressors (c-Ski, N-CoR, and mSin3A) and histone deacetylase 1, and that this interaction is required for transcriptional repression mediated by the tumor suppressor Mad. PML-RARalpha has the two corepressor-interacting sites and inhibits Mad-mediated repression, suggesting that aberrant binding of PML-RARalpha to the corepressor complexes may lead to abrogation of the corepressor function. These mechanisms may contribute to events leading to leukemogenesis.

[Inhibition of HBV gene expression by antisense oligonucleotides using galactosylated poly (L-lysine) as a hepatotropic carrier]

OBJECTIVE

To study the specific inhibition of HBV gene expression by antisense oligonucleotide (ASON) targeted by galactosylated poly (L-lysine) (Gal-PLL).

METHODS

According to the results of direct sequencing of PCR amplified products, a 16 mer phosphorthioate analogue of the antisense oligonucleotide (PS-ASON) directed against the HBV U5-like region was synthesized and then linked with one liver-targeting ligand, the Gal-PLL. Using the 2.2.15 cells compared the effect of them on the expression of HBV gene.

RESULTS

We identified that HBV DNA in the 2.2.15 cells was from HBV with surface antigen subtype ayw2 by sequencing. The fluorescent histochemistry test indicted that Gal-PLL had a selective affinity to the rat liver tissues. A 2:1 molar ratio of the Gal-PLL to DNA optimized the complex formation. In the same experimental conditions, the inhibitory effects of HBsAg and HBeAg by PS-ASON were 70% and 58%, respectively at a concentration of 10 mumol/L, while by ligand-PS-ASON were 96% and 82%, respectively, and the amount of HBV DNA in culture supernatant and cells was depressed significantly. An unrelated sequence oligonucleotide showed no effectiveness. All the oligonucleotide had no cytotoxicity.

CONCLUSION

Antisense oligonucleotides complex with the liver-targeting ligand can be targeted to cells via asialoglycoprotein receptors resulting in specific inhibition of HBV gene expression and replication.

Organ-specific activation of activator protein-1 in transgenic mice by 12-o-tetradecanoylphorbol-13-acetate with different administration methods

12-O-Tetradecanoylphorbol-13-acetate (TPA) is widely used as a tumor promoter with organotropy in skin and esophagus. TPA-induced, organ-specific tumor promotion is not correlated with the distribution of its receptor, protein kinase C (PKC). Using five administration methods (painting, drinking, gavage feeding, i.p. injection, and i.v. injection), we analyzed TPA-stimulated activator protein-1 (AP-1) activity in various organs (liver, kidney, brain, lung, spleen, heart, stomach, colon, esophagus, and skin) from transgenic mice expressing the AP-1 luciferase reporter gene. Topical application of TPA by painting the skin on the back of mice raised AP-1 activity 122.6-fold, and the highest peak of AP-1 activity was at 12 h after administration of TPA. Drinking water containing TPA caused a 25.8-fold induction of AP-1 activity in the skin, whereas gavage feeding with TPA caused a 34.2-fold induction of AP-1 in the skin. Intraperitoneal or i.v. injection of TPA induced a 49.56-fold or 20.4-fold increase in AP-1 activity in the skin, respectively. The highest peaks of AP-1 activity in the skin were at 12 h after drinking, feeding, or injection of TPA. More interesting, in the esophagus, i.p. injection of TPA raised AP-1 activity 13.9-fold, drinking TPA raised AP-1 activity 8.4-fold, and painting with TPA caused a 2.4-fold induction of AP-1 activity. In the colon, i.p. injection of TPA raised AP-1 activity 3.9-fold, drinking TPA induced a 1.2-fold increase in AP-1 activity, but painting with TPA had no effect. AP-1 activity in other organs was not detectable after administration of TPA by painting, drinking, or injection. Phosphorylation of extracellular signal-regulated kinases in the skin increased at 12 h after painting, drinking, or i.p. injection of TPA. In addition, phosphorylation of p38 kinase was raised slightly after TPA administration, but phosphorylation of c-Jun NH(2)-terminal kinases was not detected at any time point after TPA administration. Similar changes in MAP kinases were also seen in the esophagus after TPA administration. These results indicate that the skin is the most sensitive organ to TPA induction of AP-1 activity. The data suggest that the organ-specific, tumor-promoting effect of TPA may be through AP-1 activation and phosphorylation of ERKs and p38 kinase.

Mitogen- and stress-activated protein kinase 1 mediates activation of Akt by ultraviolet B irradiation

In this study, we investigated the mechanism by which UVB irradiation activates Akt (also known as protein kinase B (PKB)) in mouse epidermal JB6 cells. Treatment with a phosphatidylinositol 3-kinase inhibitor, LY 294002, or expression of a dominant negative mutant of p85 (regulatory component of phosphatidylinositol 3-kinase) inhibited UVB-induced Akt activation. Interestingly, Akt activation by UVB was attenuated by treatment with PD 98059, a specific mitogen-activated protein kinase/extracellular signal-regulated protein kinase (Erk) kinase 1 inhibitor, or SB 202190, a specific p38 kinase inhibitor. Furthermore, the expression of a dominant negative mutant of Erk2 or p38 kinase, but not that of c-Jun N-terminal kinase 1 (JNK1), blocked UVB-induced Akt activation. The expression of a dominant negative mutant of p85 or treatment with LY 294002 also inhibited UVB-induced Erk phosphorylation. The UVB-activated mitogen-activated protein kinase members, which were immunoprecipitated from cells exposed to UVB, did not phosphorylate Akt. Instead, Akt was phosphorylated at both threonine 308 and serine 473 and activated by UVB-activated mitogen- and stress-activated protein kinase 1 (Msk1). The expression of a Msk1 C-terminal kinase-dead mutant inhibited UVB-induced phosphorylation and activation of Akt. These data thus suggested that UVB-induced Akt activation was mediated through Msk1, which is a downstream kinase of the Erk and p38 kinase signaling pathways.

UVA induces Ser381 phosphorylation of p90RSK/MAPKAP-K1 via ERK and JNK pathways

UVA exposure plays an important role in the etiology of skin cancer. The family of p90-kDa ribosomal S6 kinases (p90(RSK)/MAPKAP-K1) are activated via phosphorylation. In this study, results show that UVA-induced phosphorylation of p90(RSK) at Ser(381) through ERKs and JNKs, but not p38 kinase pathways. We provide evidence that UVA-induced p90(RSK) phosphorylation and kinase activity were time- and dose-dependent. Both PD98059 and a dominant negative mutant of ERK2 blocked ERKs and p90(RSK) Ser(381) phosphorylation, as well as p90(RSK) activity. A dominant negative mutant of p38 kinase blocked UVA-induced phosphorylation of p38 kinase, but had no effect on UVA-induced Ser(381) phosphorylation of p90(RSK) or kinase activity. UVA-induced p90(RSK) phosphorylation and kinase activity were markedly attenuated in JnK1(-/-) and JnK2(-/-) cells. A dominant negative mutant of JNK1 inhibited UVA-induced JNKs and p90(RSK) phosphorylation and kinase activity, but had no effect on ERKs phosphorylation. PD169316, a novel inhibitor of JNKs and p38 kinase, inhibited phosphorylation of p90(RSK), JNKs, and p38 kinase, but not ERKs. However, SB202190, a selective inhibitor of p38 kinase, had no effect on p90(RSK) or JNKs phosphorylation. Significantly, ERKs and JNKs, but not p38 kinase, immunoprecipitated with p90(RSK) when stimulated by UVA and p90(RSK) was a substrate for ERK2 and JNK2, but not p38 kinase. These data indicate clearly that p90(RSK) Ser(381) may be phosphorylated by activation of JNKs or ERKs, but not p38 kinase.