GSK3 beta mediates suppression of cyclin D2 expression by tumor suppressor PTEN

PTEN, encoding a lipid phosphatase, is a tumor suppressor gene and is mutated in various types of cancers. It is reported to regulate G1 to S phase transition of the cell cycle by influencing the expression, protein stability and subcellular location of cyclin D1. Here, we provide evidence that PTEN modulates the transcription and protein stability of cyclin D2. Targeted deletion of Pten in mouse embryonic fibroblasts (MEFs) endowed cells with greater potential to overcome G1 arrest than wild-type MEFs and led to the elevated expression of cyclin D2, which was suppressed by the introduction of PTEN. We further defined a pathway involving GSK3beta and beta-catenin/TCF in PTEN-mediated suppression of cyclin D2 transcription. LiCl, an inhibitor of GSK3beta, abolished inhibitory effect of PTEN on cyclin D2 expression, and TCF members could directly bind to the promoter of cyclin D2 and regulate its transcription in a CREB-dependent manner. Our results indicate that the downregulation of cyclin D2 expression by PTEN is mediated by the GSK3beta/beta-catenin/TCF pathway in cooperation with CREB, and suggest a convergence from the PI-3 kinase/PTEN pathway and the Wnt pathway in modulation of cyclin D2 expression.

The genome of black cottonwood, Populus trichocarpa (Torr. & Gray)

We report the draft genome of the black cottonwood tree, Populus trichocarpa. Integration of shotgun sequence assembly with genetic mapping enabled chromosome-scale reconstruction of the genome. More than 45,000 putative protein-coding genes were identified. Analysis of the assembled genome revealed a whole-genome duplication event; about 8000 pairs of duplicated genes from that event survived in the Populus genome. A second, older duplication event is indistinguishably coincident with the divergence of the Populus and Arabidopsis lineages. Nucleotide substitution, tandem gene duplication, and gross chromosomal rearrangement appear to proceed substantially more slowly in Populus than in Arabidopsis. Populus has more protein-coding genes than Arabidopsis, ranging on average from 1.4 to 1.6 putative Populus homologs for each Arabidopsis gene. However, the relative frequency of protein domains in the two genomes is similar. Overrepresented exceptions in Populus include genes associated with lignocellulosic wall biosynthesis, meristem development, disease resistance, and metabolite transport.

Retrovirus molecular conjugates: a versatile and efficient gene transfer vector system for primitive human hematopoietic progenitor cells

In principle, transient nongenetic modification of a noninfectious gene transfer virus enabling a one time infection and transduction of human cells could eliminate the risk of formation of replication competent virus. Formation of a molecular conjugate vector by conjugation of noninfective ecotropic murine Moloney leukemia virus to polylysine (eMMLV-PL) enabled high-efficiency transduction of human HPC using in vitro and in vivo assays. Xenotransplanted NOD-SCID mice durably expressed the transgene in human leukocytes and human progenitor cells with eMMLV-PL achieving three-fold increased transduction efficiency when directly compared to optimized amphotropic MMLV (aMMLV) transduction. Both aMMLV and eMMLV assembled conjugate vectors showed similar transduction efficiency indicating predominant polylysine-mediated uptake. Integration of retroviral sequences was determined from individual human HPC recovered from eMMLV-PL-xenotransplanted animals. This simple and versatile concept of conjugate gene transfer vectors has the potential to enhance transduction efficiency as well as to improve certain safety aspects of human gene therapy. Moreover, because it permits effective cellular internalization of particles, this concept of molecular conjugates can be used as research tool to investigate the interactions of otherwise noninfectious viruses or modified viral particles at the genomic level.

Characterization and expression of a cDNA encoding a tubuliform silk protein of the golden web spider Nephila antipodiana

Spider silks are renowned for their excellent mechanical properties. Although several spider fibroin genes, mainly from dragline and capture silks, have been identified, there are still many members in the spider fibroin gene family remain uncharacterized. In this study, a novel silk cDNA clone from the golden web spider Nephila antipodiana was isolated. It is serine rich and contains two almost identical fragments with one varied gap region and one conserved spider fibroin-like C-terminal domain. Both in situ hybridization and immunoblot analyses have shown that it is specifically expressed in the tubuliform gland. Thus, it likely encodes the silk fibroin from the tubuliform gland, which supplies the main component of the inner egg case. Unlike other silk proteins, the protein encoded by the novel cDNA in water solution exhibits the characteristic of an alpha-helical protein, which implies the distinct property of the egg case silk, though the fiber of tubuliform silk is mainly composed of beta-sheet structure. Its sequence information facilitates elucidation of the evolutionary history of the araneoid fibroin genes.

Gold-Labeled Nanoparticle-Based Immunoresonance Scattering Spectral Assay for Trace Apolipoprotein AI and Apolipoprotein B

Background: Apolipoprotein AI (ApoAI) and ApoB are risk indicators of cardiovascular disease. We describe the use of immunoresonance scattering to measure the ApoAI and ApoB in serum.

Methods: We used a trisodium citrate method to prepare 9.0-nm gold nanoparticles labeled with goat anti-human ApoAI and ApoB antibodies. The immune reaction between gold-labeled antibodies and antigens took place in Na2HPO4-NaH2PO4 buffer solution (pH 6.4 for ApoAI and pH 6.0 for ApoB) in the presence of 75 g/L polyethylene glycol (PEG). We used a transmission electron microscope to observe the shape of the gold nanoparticles. Results were compared with those obtained by immunoturbidimetric methods. Twenty-five human serum samples were assayed by the immunoresonance scattering assay preset with the data indicated and by an immunoturbidimetric assay.

Results: The presence of PEG greatly enhanced the intensity of resonance-scattering peaks at 560 nm. The intensity (ΔI) was proportional to concentration at 0.00833–0.3333 mg/L ApoAI and 0.00197–0.1972 mg/L ApoB. The detection limits were 2.04 and 0.96 μg/L for ApoAI and ApoB, respectively. The results for human serum samples were in agreement with those obtained with an immunoturbidimetric method. Linear regression analysis revealed a correlation coefficient, slope, and intercept of 0.915, 0.966, and 68.53 mg/L, respectively, for ApoAI and 0.919, 0.996, and 15.46 mg/L for ApoB.

Conclusion: This method showed high sensitivity and good selectivity for quantitative determination of ApoAI and ApoB in human serum, with satisfactory results.

P53 as a predictor of tumor burden in lymph nodes (LN) in colon cancer (Cca) patients (pts) undergoing sentinel lymph node (SLN) mapping (M)

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Background: p53 and LN status(S) are important prognostic markers in Cca. Our study was done to evaluate whether p53 S could predict tumor burden in LNs in Cca undergoing SLNM. Methods: Pts with Cca underwent SLNM to determine the LN S. A portion of tumor was used for detection of p53 S by IHC.p53 Histo Score (HS) was defined as (Intensity of stain in cells from 0–4 +1) × (% cells staining). HS of 180 was taken as cut off for significance based on previous studies on solid tumors. Metastatic foci in SLNs and nonSLNs were measured in greatest diameter by ocular micrometer. For overall tumor burden in SLNs and nonSLNs,all metastatic foci were added for each pt. Results: SLNM was successful in 100% of the 117 consecutive pts with Cca. Pts with distant metastasis (mets) (18) and skip mets (9) were excluded. Of the remaining 90 pts,39% were SLN positive (+ve) and 61% were SLN negative (-ve). HS of ≤ 180 was found in 66% and HS >180 was found in 34% of the pts. In 55 SLN -ve pts 76% had HS ≤ 180 while 24% had HS >180. In 35 SLN +ve pts, 49% had HS of ≤ 180 and 51% had HS >180. ( Table ) Of SLN +ve pts, size of metastatic tumor in LNs was available in 86% of pts. Average (av.) non SLN met size was 0.95 cms in pts with HS ≤ 180 and 3.4 cms in pts with HS > 180. Av. SLN met size was 0.63 cms in pts with HS ≤ 180 and 0.9 cms in pts with HS>180 ( Table ). No statistical significance was found among T stage of pts with HS >180 vs ≤ 180. Conclusion: Pts with p53 HS >180 showed significantly greater tumor burden in both SLNs and non SLNs as compared to pts with HS ≤ 180. Also probability of having SLN -ve disease is higher in pts with HS ≤ 180 as compared to pts with HS >180 in Cca. Thus,even in SLN -ve pts, high HS may indicate a worse prognosis. Hence,a high p53 HS might predict pts with Cca having higher tumor burden in LNs and thus identify an aggressive subgroup of pts.

[Table: see text]

No significant financial relationships to disclose.

In vitro drug resistance profiles correlate with DNA ploidy and p53 expression in 3,106 endometrioid and papillary serous adenocarcinomas of the uterus

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Background: Although chemotherapy is widely used to treat advanced and recurrent endometrial cancer, no patient-tailored protocols were developed, resulting in intermittent and incomplete clinical response. The utility of the Extreme Drug Resistance (EDR) assay to predict clinical resistance to chemotherapy was proven in several cancer types, including ovarian cancer. This study is the first attempt to evaluate the efficacy of the EDR assay in endometrioid (E) and papillary serous (PS) tumors and correlate it with the expression of two major biomarkers, DNA ploidy and p53. Methods: 2520 E and 586_PS adenocarcinomas were tested in the EDR assay using in vitro incubation in suprapharmacologic exposures of 4-HC (the active species of cyclophosphamide), cisplatin, carboplatin, and doxorubicin. The results were defined as EDR (one standard deviation more resistant than the database median), intermediate drug resistance (IDR - between the median and EDR), and low drug resistance (LDR - lower than the median). DNA ploidy was assessed in flow cytometry; p53 expression was quantitated on paraffin sections by immunohistochemistry. Results: Compared to E, the more clinically aggressive PS tumors were significantly associated with high (IDR + EDR) in vitro resistance to all EDR-tested drugs: 4-HC (p = 0.0010; χ2 statistics), cisplatin (p = 0.0064), carboplatin (p = 0480), doxorubicin (p = 0.0001). PS tumors showed significantly higher non-diploid status (p < 0.0001) and p53-positivity (p < 0.0001). For all EDR-tested drugs, increased in vitro resistance closely correlated with the non-diploid and high p53 status. Conclusions: These data document close correlation between the EDR assay results and biological behavior of endometrial tumors in terms of their clinical aggressiveness and biomarker expression and justify further studies on combined EDR and biomarker testing in assay-guided chemotherapy.

[Table: see text]

No significant financial relationships to disclose.

Genetic heterogeneity in acrokeratosis verruciformis of Hopf

BACKGROUND

Acrokeratosis verruciformis of Hopf (AKV) is a rare genodermatosis characterized by multiple flat-topped, flesh-coloured papules on the dorsa of hands and feet, and punctuate keratoses on the palms and soles. A mutation in the ATP2A2 gene has been shown to be associated with AKV and with Darier's disease (DD).

OBJECTIVES

To explore the molecular aetiology of AKV and DD.

METHODS

We investigated the clinical and histological information in two families and a sporadic case with AKV and one family and a sporadic case with DD in China. Mutation analysis of ATP2A2 was performed by PCR and direct sequencing, and genotyping and linkage analysis performed using six polymorphic microsatellite markers spanning the locus at 12q23-12q24 containing ATP2A2.

RESULTS

Mutational analysis showed no mutation in ATP2A2 among the AKV patients, but we found two novel mutations (p.C318F and p.M719fs) in the DD patients. The genotyping and linkage analysis results revealed no linkage evidence of the locus at 12q23-12q24 in a large AKV family.

CONCLUSIONS

Our findings provide evidence for the genetic heterogeneity of AKV and demonstrate that mutations in genes other than ATP2A2 are responsible for AKV in a proportion of the Chinese population.

Acetylcholinesterase expression mediated by c-Jun-NH2-terminal kinase pathway during anticancer drug-induced apoptosis

It has been shown that acetylcholinesterase (AChE) expression was induced during apoptosis and the anti-sense oligonucleotides and siRNA of AChE may prevent apoptosis in various cell types. However, the mechanisms underlying AChE upregulation remain elusive. We demonstrated here that c-Jun NH2-terminal kinase (JNK) could mediate AChE expression. In this study, both etoposide and excisanin A, two anticancer agents, induced apoptosis in colon cancer cell line SW620 as determined by Annexin V staining, the cleavage of caspase-3 and the proteolytic degradation of poly (ADP-ribose) polymerase (PARP). The results showed that both the agents upregulated AChE in SW620 cells. In the meantime, JNK was also activated and the expression and phosphorylation of c-Jun increased in SW620 cells exposed to the two agents. The induced AChE mRNA and protein expression could be blocked by SP600125, a specific inhibitor of SAPK/JNK, and small interfering RNA directed against JNK1/2. Transfection with adenovirus-mediated dominant negative c-Jun also blocked the upregulation of AChE expression. Together, these results suggest that AChE expression may be mediated by the activation of JNK pathway during apoptosis through a c-Jun-dependent mechanism.

Mechanisms responsible for surfactant changes in sepsis-induced lung injury

Pulmonary surfactant is altered in sepsis, and these changes contribute to the predisposition of septic lungs to subsequent insults, ultimately leading to acute lung injury. Specifically, the total amount of surfactant is lower in sepsis, mainly due to decreased small aggregate (SA) surfactant pools. The amount of large aggregate (LA) surfactant is not altered. To evaluate the mechanisms responsible for these alterations, trace doses of tritium-labelled dipalmitoylphosphatidylcholine (3H-DPPC)-labelled LA were instilled intratracheally into adult rats 20 hrs after caecal ligation and perforation (CLP) or sham surgery. Animals were sacrificed at 0, 1 and 4 h after instillation and recovery of 3H-DPPC in alveolar macrophages (AM), LA and SA was measured. In separate in vitro experiments, AM isolated from CLP/sham rats were incubated with LA or SA isolated from normal animals to evaluate the uptake of these aggregates into the AM. Results showed increased surfactant radioactivity associated with AM of CLP animals compared with sham animals both in vivo and in vitro. In addition, more 3H-DPPC label remained in LA forms in the CLP animals in vivo compared with sham. These findings indicate that differences in surfactant aggregate uptake and large aggregate conversion occur in septic lungs, resulting in changes in surfactant pools.

Longitudinal MR spectroscopic imaging of pediatric diffuse pontine tumors to assess tumor aggression and progression

Two pediatric patients with diffuse pontine tumors underwent MR spectroscopic imaging pre- and postradiation. Choline/creatine (Cho/Cr) and Cho/N-acetylaspartate (NAA) ratios were elevated before treatment, with no MR imaging contrast enhancement. These ratios were further elevated at 2 posttreatment follow-up studies, despite signs of excellent clinical improvement at initial follow-up. This study suggests that MR spectroscopic imaging is more specific in assessing the aggressiveness of diffuse pontine tumors than conventional MR imaging and can serve as a valuable tool in early prognostication.

Methionine Requirements of Male White Peking Ducks from Twenty-One to Forty-Nine Days of Age

A dose-response experiment with 6 dietary methionine levels (0.20, 0.275, 0.35, 0.425, 0.50, and 0.575%) was conducted with male White Peking ducklings to estimate the methionine requirement of growing ducks from 21 to 49 d of age. One-day-old male White Peking ducklings were fed common starter diets from hatching to 21 d of age and then fed the experimental diets from 21 to 49 d of age. Three hundred thirty-six 21-d-old birds were allotted to 24 pens with 14 birds per pen according to similar pen weight. There were 6 dietary treatments, each containing 4 replicate pens. At 49 d of age, weight gain, feed intake, and feed/gain of ducks from each pen were measured, and 2 ducks selected randomly from each pen were slaughtered to evaluate the yields of abdominal fat, breast meat (including pectoralis major and pectoralis minor), and leg meat (including thigh and drum stick). Significant effects of dietary methionine on weight gain, breast meat, and abdominal fat were observed. Both weight gain and breast meat yield showed significant quadratic response to increasing dietary methionine, and abdominal fat decreased linearly (P < 0.05). According to the quadratic model, the optimal methionine requirement of male White Peking ducks from 21 to 49 d of age for maximum weight gain and breast meat yield were 0.377 and 0.379%, respectively.

Growth mechanism of tubular ZnO formed in aqueous solution

Tubular ZnO microstructural arrays were fabricated by a hydrothermal decomposition method. The dependence of the morphologies on the growth time and temperature was investigated in detail. An experiment was carried out to determine the mechanism of tubular ZnO formation. Our results showed that ZnO microtubes originated from an ageing process from ZnO microrods at a lower temperature (compared to the temperature when hydrothermal deposition of ZnO microrods was dominant) due to the preferential chemical dissolution of the metastable Zn-rich (0001) polar surfaces. A growth model was proposed based on the coexistence of hydrothermal deposition and dissolution of ZnO in the fabrication process.

Effects of Anti-Bursin Monoclonal Antibody on Immunosuppression in the Duck (Cherry Valley Duck)

To study the immunologic function of bursin, we analyzed the effects of anti-bursin monoclonal antibody (mAb) on the immunosuppression in ducks (Cherry Valley duck) by injecting various doses of the anti-bursin mAb into 13-d duck embryos. After hatch, cell-mediated immune activity and humoral responses were studied using lymphocyte proliferation test, tube agglutination test, and indirect enzyme-linked immunosorbent assay to detect anti-Escherichia coli antibodies and antibodies to Riemerella anatipestifer, respectively. Simultaneously, relative weights (BW-adjusted) of bursa of Fabricius (BF), spleen, and thymus were determined. Additionally, the morphology of BF, spleen, and thymus was examined at various ages using conventional histology. Follicle morphology of BF was analyzed by image analysis. The results indicated that anti-bursin mAb markedly decreased duck lymphocyte proliferation, the antibody-producing ability to bacteria, as well as the relative BF weight. Moreover, the anti-bursin mAb hindered the development of BF follicles.

trans-Stilbene oxide induces expression of genes involved in metabolism and transport in mouse liver via CAR and Nrf2 transcription factors

trans-Stilbene oxide (TSO) induces drug metabolizing enzymes in rat and mouse liver. TSO is considered a phenobarbital-like compound because it induces Cyp2B mRNA expression in liver. Phenobarbital increases Cyp2B expression in liver via activation of the constitutive androstane receptor (CAR). The purpose of this study was to determine whether TSO induces gene expression in mouse liver via CAR activation. TSO increased CAR nuclear localization in mouse liver, activated the human Cyp2B6 promoter in liver in vivo, and activated a reporter plasmid that contains five nuclear receptor 1 (NR1) binding sites in HepG2 cells. TSO administration increased expression of Cyp2b10, NAD(P)H:quinone oxidoreductase (Nqo1), epoxide hydrolase, heme oxygenase-1, UDP-glucuronosyl-transferase (Ugt) 1a6 and 2b5, and multidrug resistance-associated proteins (Mrp) 2 and 3 mRNA in livers from male mice. Cyp2b10 and epoxide hydrolase induction by TSO was decreased in livers from CAR-null mice, compared with wild-type mice, suggesting CAR involvement. In contrast, TSO administration induced Nqo1 and Mrp3 mRNA expression equally in livers from wild-type and CAR-null mice, suggesting that TSO induces expression of some genes through a mechanism independent of CAR. TSO increased nuclear staining of the transcription factor Nrf2 in liver, and activated an antioxidant/electrophile response element luciferase reporter construct that was transfected into HepG2 cells. In summary, in mice, TSO increases Cyp2b10 and epoxide hydrolase expression in mice via CAR, and potentially induces Nqo1 and Mrp3 expression via Nrf2. Moreover, our data demonstrate that a single compound can activate both CAR and Nrf2 transcription factors in liver.

Effect of combined treatment with nandrolone and cocaine on the NMDA receptor gene expression in the rat nucleus accumbens and periaqueductal gray

OBJECTIVE

Anabolic androgenic steroids (AAS) have been suggested to sensitize mechanisms involved in drug dependency and aggressive behaviour. Nucleus accumbens and periaqueductal gray (PAG) are believed to be critical in the functional anatomy of these two phenomena, which are partly mediated by the NMDA receptor. This study was undertaken in order to determine the relationship between the effect of AAS and cocaine (given alone or in combination) on the gene expression of the NMDA receptor subtype NR1 in the rat nucleus accumbens and PAG.

METHOD

Male rats were subjected to 2 weeks of daily doses of cocaine and the anabolic-androgenic steroid nandrolone, administrated separately or in combination, and the effect on the mRNA expression for the NMDA receptor NR1 subunit was studied by Northern blot analysis.

RESULTS

In the nucleus accumbens, injection of cocaine alone and the combination of cocaine and nandrolone caused a significant decrease in the NR1 mRNA level compared with that of control rats. The combined treatment significantly down-regulated the transcript in the PAG compared with the groups injected with vehicle, nandrolone or cocaine alone.

CONCLUSION

It was concluded that AAS combined with cocaine may induce additive increases in glutamatergic activity in these brain areas, supporting the notion that these steroids can sensitize mechanisms involved in the reward and the expression of aggression.

Refined localization of a punctate palmoplantar keratoderma gene to a 5.06-cM region at 15q22.2-15q22.31

BACKGROUND

Punctate palmoplantar keratoderma (PPK) is a rare autosomal dominant cutaneous disorder characterized by numerous hyperkeratotic papules distributed on the palms and soles. Two loci for punctate PPK were recently found to be located on 8q24.13-8q24.21 and 15q22-15q24. However, no genes for this disease have been identified to date. Objectives To refine the previously mapped regions and to identify the disease gene locus in a four-generation Chinese family with punctate PPK.

METHODS

Genetic linkage analysis was carried out in this family using microsatellite markers on chromosomes 8q and 15q. Two-point linkage analysis was performed using Linkage programs version 5.10 and the haplotype was constructed using Cyrillic version 2.02 software.

RESULTS

We failed to confirm our previous locus at 8q24.13-8q24.21, but significant evidence for linkage was observed in the region of 15q with a maximum two-point LOD score of 5.38 at D15S153 (theta = 0.00). Haplotype analysis localized the punctate PPK locus within the region defined by D15S651 and D15S988. This region overlaps by 5.06 cM with the previously reported punctate PPK region.

CONCLUSIONS

This study refines a disease gene causing punctate PPK to a 5.06-cM interval at 15q22.2-15q22.31.

Antisense inhibition of xylitol dehydrogenase gene, xdh1 from Trichoderma reesei

AIMS

To inhibit xylitol dehydrogenase (XDH) in Trichoderma reesei by antisense inhibition strategy and construct novel strains capable of accumulating xylitol.

METHODS AND RESULTS

The xdh1 antisense expression plasmid pGTA-xdh was constructed by inserting xdh1 DNA fragment inversely between the gpdA promoter and the trpC terminator from Aspergillus nidulans into a pUC19 plasmid backbone. Trichoderma reesei protoplasts were co-transformated with pGTA-xdh and hygromycin B resistance plasmid pAN7-1. Of 20 transformants screened from the selective medium, one transformant with the highest xylitol accumulation, designated ZY15, showed a distinct reduction (c. 52%) in XDH activity compared with the original strain Rut-C30. The results of Southern hybridization and PCR assay showed that the antisense expression cassette of xdh1 was integrated into the genome of T. reesei. The RT-PCR analysis proved that antisense RNA effectively inhibited XDH expression (c. 65%). Xylitol accumulation (2.37 mg ml(-1)) of ZY15 was five times higher than that (0.46 mg ml(-1)) of the original strain Rut-C30.

CONCLUSIONS

Strain ZY15 successfully downregulated XDH production and exhibited xylitol accumulation in xylose liquid medium.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study contributed to the budding field of fungal genetics in two points. First, it confirmed that antisense RNA strategy could be used as a means of reducing gene expression in the filamentous fungus T. reesei. Secondly, it verified that the strategy appears most promising for creating novel filamentous fungi strains capable of accumulating intermediary metabolites.