Decreased expression of haem oxygenase-1 by alveolar macrophages in idiopathic pulmonary fibrosis

Haem oxygenase (HO)-1 is an oxidative stress responsive protein that may be involved in the pathogenesis of interstitial lung disease. HO-1 expression in alveolar macrophages from bronchoalveolar lavage was investigated in 24 patients with idiopathic pulmonary fibrosis (IPF), 16 with sarcoidosis, 14 with hypersensitivity pneumonitis (HP) and 13 controls. Using immunocytochemistry, HO-1 expression in macrophages was scored semiquantitatively from 0-3 according to increasing intensity. The mean score of 100 macrophages was calculated. Macrophages were cultured and levels of interleukin (IL)-12 and IL-18 in the culture supernatants were measured by ELISA. The mean score of HO-1 was significantly lower in IPF (67) than in sarcoidosis (105), HP (106) or controls (106). There was no significant difference between sarcoidosis, HP and controls. The score of HO-1 correlated positively with the lymphocyte percentage in sarcoidosis and HP. Positive correlations were found between the score of HO-1 and the release of IL-12 and IL-18 by macrophages in IPF. The expression of haem oxygenase-1, a critical defender against oxidative stress, is decreased in macrophages of idiopathic pulmonary fibrosis patients compared with those with granulomatous lung disorders. This supports the hypothesis of an oxidant-antioxidant imbalance in the pathogenesis of idiopathic pulmonary fibrosis.

Ion pathways in the taste bud and their significance for transduction

Taste buds share a topology with ion-transporting epithelial and evidence now indicates that neural responses in rats to Na+ salts of differing anion are mediated by both transcellular and paracellular ion transport. Na+ exerts its effects mainly on the transcellular pathway. Neural responses to Na+ salts are enhanced by negative voltage clamp and suppressed by positive clamp in a manner indicating modulation of the apical membrane potential of receptor cells. Anion effects are mainly paracellular. Under zero current clamp increasing anion size reduces the neural response at constant Na+ concentration. Below about 50 mM this difference is entirely eliminated under voltage clamp. This suggests that paracellular transepithelial potentials normally create an anion difference. At higher concentrations the relatively high permeability of the paracellular shunt to Cl- permits sufficient electroneutral diffusion of NaCl below the tight junctions to stimulate cells that do not make direct contact with the oral cavity. In general, the sensitivity of a response to perturbations in the apical membrane potential indicates that some phase of Na+ salt taste transduction is accompanied by changes in an apical membrane channel conductance.

Antimicrobial resistance and serotypes of nasopharyngeal strains of Streptococcus pneumoniae in Chinese children with acute respiratory infections

This prospective, multicentre, nasal carriage study in Chinese children with upper respiratory infection was carried out over the period from 2000 to 2002. Overall, the prevalence of pneumococcal carriage was 24.9%. Antimicrobial susceptibility tests were performed for 887 isolates of Streptococcus pneumoniae of which 33.5% were intermediately susceptible to penicillin and 6.4% were resistant. Multidrug resistance was very common. Pneumococcal strains (n = 625) were serotyped, showing 72.2% were covered by the 23-valent pneumococcal polysaccharide vaccine and 57.6% by the seven-valent pneumococcal conjugate vaccine. Serogroups 19 and 23 were significantly associated with penicillin resistance, which is increasing in China. Erythromycin, tetracycline and sulphamethoxazole/trimethoprim cannot be recommended as first-line treatments for respiratory tract infection as in some other developing countries. These features of serotype distribution are of importance for surveillance in the era of the new conjugate vaccine. In particular, these features will allow for documentation of serotype replacement after the introduction of widespread vaccination.

Extracellular cleaved HER2 (p95) confers partial resistance to trastuzumab but not HSP90 inhibitors in models of HER2 amplified breast cancer

10515

Background: Breast cancers containing an amplified copy of the HER2 receptor tyrosine kinase represent 20–30% of all cases and antibody directed therapy targeting the extracellular domain of HER2 with trastuzumab has proven broadly efficacious. However, resistance to trastuzumab is a common phenomenon. Recent work has identified a cleaved, 95kD version of HER2 that lacks the extracellular epitope in which the trastuzumab binding site is found. Presence of this so called “p95” has been correlated with a worse clinical prognosis. We hypothesized that p95 may enable tumor resistance to trastuzumab. Methods/Results: We established models of p95 expressing breast cancer by transfecting p95 into preexisting models of HER2 amplified breast cancer. We find that cells expressing p95 display increased resistance to the growth inhibitory effects of trastuzumab. The PI3K-AKT pathway that is downregulated by Trastuzumab is less affected in the p95 expressing cells. Furthermore, p95 demonstrates an association with HER3 that is unaffected by trastuzumab treatment. Next, we evaluated the efficacy of therapies targeted against the intracellular domain of HER2 such as the HSP90 inhibitor, 17-AAG. HER2 requires HSP90 for its conformational stability and inhibitors of HSP90 result in growth inhibition of HER2+ breast cancer. We find that p95 displays a similar requirement for HSP90 as inhibitors of HSP90 result in the degradation of p95. Moreover, cells overexpressing p95 are equally susceptible to the antitumor effects of HSP90 inhibitors as those without high levels of p95. Finally, we utilized an empirically derived, in vivo model of trastuzumab resistance that displays high level expression of p95. As with the transfected models, these tumors retain their sensitivity to HSP90 inhibitors as treatment of mice bearing tumors results in both degradation of HER2 and p95 as well as robust tumor growth inhibition. Conclusions: Given the presence of p95 in human breast tumor samples, the data suggest that p95 may play an important role in mediating clinical resistance to trastuzumab. They further suggest that such tumors may retain their sensitivity to targeted therapy against the intracellular portion of HER2 such as with lapatinib or 17-AAG.

No significant financial relationships to disclose.

SAR studies on a novel series of human cytomegalovirus primase inhibitors

A novel series of imidazolylpyrimidines were found to possess inhibitory activity against the human CMV UL70 primase. Extensive SAR studies on an HTS lead led to potent, orally bioavailable compounds with anti-CMV IC(50) values of 150 nM in both viral yield and viral DNA replication assays and with a much reduced cytotoxicity compared to marketed treatments ganciclovir and cidofovir.

Tissue type-specific modulation of ER transcriptional activity by NFAT3

NFAT3 belongs to the NFAT family of transcription factors playing important roles in the development of several organ systems and was found to act as a transcriptional coactivator of estrogen receptors (ERalpha and ERbeta) in breast cancer cells. Since some cofactors of transcription factors show cell or tissue type-specific effects on transcriptional regulation, we investigated the effect of NFAT3 on the transcriptional activity of ERs in different cell lines originated from kidney. Surprisingly, overexpression of NFAT3 in these cell types decreased dose-dependently both ERalpha and ERbeta transcriptional activities in a ligand-independent manner. Knockdown of endogenous NFAT3 using NFAT3 small interfering RNA (siRNA) increased ER transcriptional activities. NFAT3 deletion mutants lacking the ER-binding sites completely abolished the NFAT3 repression of ERalpha and ERbeta transcriptional activities. Replacement of Ser168 and Ser170, the amino acid residues on which NFAT3 can be phosphorylated, with Ala did not change the ability of NFAT3 to inhibit the transcriptional activity of ERalpha and ERbeta. Taken together, these results demonstrate that NFAT3 is a new kind of cofactor that displays dual transcription modulation mode dependent on tissue types.

Potentiation of Smad-mediated transcriptional activation by the RNA-binding protein RBPMS

Smad2, Smad3 and Smad4 proteins are considered to be key mediators of transforming growth factor-beta (TGF-beta) signaling. However, the identities of the Smad partners mediating TGF-beta signaling are not fully understood. Here, we show that RNA-binding protein with multiple splicing (RBPMS), a member of the RNA-binding protein family, physically interacts with Smad2, Smad3 and Smad4 both in vitro and in vivo. The presence of TGF-beta increases the binding of RBPMS with these Smad proteins. Consistent with the binding results, overexpression of RBPMS enhances Smad-dependent transcriptional activity in a TGF-beta-dependent manner, whereas knockdown of RBPMS decreases this activity. RBPMS interacts with TGF-beta receptor type I (TbetaR-I), increases phosphorylation of C-terminal SSXS regions in Smad2 and Smad3, and promotes the nuclear accumulation of the Smad proteins. Moreover, RBPMS fails to enhance the transcriptional activity of Smad2 and Smad3 that lack the C-terminal phosphorylation sites. Our data provide the first evidence for an RNA-binding protein playing a role in regulation of Smad-mediated transcriptional activity and suggest that RBPMS stimulates Smad-mediated transactivation possibly through enhanced phosphorylation of Smad2 and Smad3 at the C-terminus and promotion of the nuclear accumulation of the Smad proteins.

Effects of Ischemia-Reperfusion Injury on Apolipoprotein M Expression in the Liver

The present study investigated the expression pattern of apolipoprotein M (apoM) mRNA in a rat model of hepatic ischemia-reperfusion injury (IRI). Animals were ischemic for 1 hour followed by various reperfusion times. As expected, serum alanine aminotransferase levels were significantly increased under IRI, which indicated the severity of liver injury. Hepatic mRNA levels of HSP70, which is the most common characterized protein within the family of heat-shock proteins (HSP), were significantly increased after 0.5 to 3 hours of IRI. Plasma C-reactive protein, high-density lipoprotein-cholesterol, and lipoprotein (a) levels were significantly increased after 1-hour ischemia followed by 0.5 to 3 hours of reperfusion. Interestingly, similar to HSP70, apoM mRNA levels in the liver were gradually increased after 0.5 to 3 hours of IRI, whereas it returned to a lower level after 6 or 24 hours of IRI, which indicated that hepatic apoM expression was significantly influenced by the acute phase of IRI. However, plasma apoM levels were not increased in parallel, even slightly decreasing after 0.5 or 1 hour of IRI. We concluded that apoM mRNA expression pattern, like HSP70, in the liver showed rapid, significant changes during hepatic local IRI.

Discovery of a novel series of inhibitors of human cytomegalovirus primase

Infection by human cytomegalovirus (hCMV) remains a potent threat to susceptible people throughout the world. We have discovered a series of imidazolyl-pyrimidine compounds, which were found to be irreversible inhibitors of the hCMV UL70 primase based on results from radiolabeling and SAR studies. Two promising analogs are described that rival ganciclovir and cidofovir in antiviral potency and possess improved cytotoxicity profiles.

Thalidomide reduces IL-18, IL-8 and TNF-alpha release from alveolar macrophages in interstitial lung disease

Thalidomide exhibits diverse actions of anti-inflammation, immunomodulation and anti-angiogenesis. The efficacy of thalidomide treatment in sarcoidosis with lupus pernio is thought to be due to inhibition of tumour necrosis factor (TNF)-alpha. The mechanisms that underlie the properties of thalidomide are still unclear in interstitial lung disease. The current authors investigated the potential inhibitory effects of thalidomide at concentrations of 0.1, 0.01 and 0.001 mM on the production of transforming growth factor-beta, TNF-alpha, interleukin (IL)-1beta, IL-6, IL-8, IL-10, IL-12p70, IL-12p40 and IL-18 by alveolar macrophages from bronchoalveolar lavage in patients with sarcoidosis (n = 8), hypersensitivity pneumonitis (HP; n = 8) and idiopathic pulmonary fibrosis (IPF; n = 12). In sarcoidosis and HP patients, thalidomide induced a dose-dependent, partial suppression of lipopolysacchride (LPS)-stimulated TNF-alpha, IL-12p40 and IL-18 release. At the highest thalidomide concentration (0.1 mM), LPS-stimulated IL-8 production was also suppressed. In IPF patients, although spontaneous production of TNF-alpha, IL-12p40, IL-18 and IL-8 was lower than in sarcoidosis and HP patients, with LPS stimulation the cytokines were significantly elevated and also partially inhibited by thalidomide. In conclusion, thalidomide has the potential to improve the therapeutic regimens for sarcoidosis, hypersensitivity pneumonitis and idiopathic pulmonary fibrosis by reducing tumour necrosis factor-alpha, interleukin-12p40, interleukin-18 and interleukin-8 production.

Hepatitis B virus X protein and the estrogen receptor variant lacking exon 5 inhibit estrogen receptor signaling in hepatoma cells

Hepatitis B virus (HBV) X protein (HBx) is considered to play a role in the development of hepatocellular carcinoma (HCC) during HBV infection. HCC was shown to be more prevalent in men than in women. Estrogen, which exerts its biological function through estrogen receptor (ER), can inhibit HBV replication. ERDelta5, an ERalpha variant lacking exon 5, was found to be preferentially expressed in patients with HCC compared with patients with normal livers. Here, we report the biological role of ERDelta5 and a novel link between HBx and ERalpha signaling in hepatoma cells. ERDelta5 interacts with ERalpha in vitro and in vivo and functions as a dominant negative receptor. Both ERalpha and ERDelta5 associate with HBx. HBx decreases ERalpha-dependent transcriptional activity, and HBx and ERDelta5 have additive effect on suppression of ERalpha transactivation. The HBx deletion mutant that lacks the ERalpha-binding site abolishes the HBx repression of ERalpha. HBx, ERalpha and histone deacetylase 1 (HDAC1) form a ternary complex. Trichostatin A, a specific inhibitor of HDAC enzyme, can restore the transcriptional activity of ERalpha inhibited by HBx. Our data suggest that HBx and ERDelta5 may play a negative role in ERalpha signaling and that ERalpha agonists may be developed for HCC therapy.

V600E B-Raf requires the Hsp90 chaperone for stability and is degraded in response to Hsp90 inhibitors

The Raf family includes three members, of which B-Raf is frequently mutated in melanoma and other tumors. We show that Raf-1 and A-Raf require Hsp90 for stability, whereas B-Raf does not. In contrast, mutated, activated B-Raf binds to an Hsp90-cdc37 complex, which is required for its stability and function. Exposure of melanoma cells and tumors to the Hsp90 inhibitor 17-allylamino-17-demethoxygeldanamycin results in the degradation of mutant B-Raf, inhibition of mitogen-activated protein kinase activation and cell proliferation, induction of apoptosis, and antitumor activity. These data suggest that activated mutated B-Raf proteins are incompetent for folding in the absence of Hsp90, thus suggesting that the chaperone is required for the clonal evolution of melanomas and other tumors that depend on this mutation. Hsp90 inhibition represents a therapeutic strategy for the treatment of melanoma.

Stimulatory Cross-talk between NFAT3 and Estrogen Receptor in Breast Cancer Cells

Estrogen receptors (ERalpha and ERbeta) are ligand-regulated transcription factors that play critical roles in the development and progression of breast cancer by regulating target genes involved in cellular proliferation. The transcriptional activity of ERalpha and ERbeta is known to be modulated by cofactor proteins. We used a yeast two-hybrid system and identified NFAT3 as a novel ERbeta-binding protein. NFAT3 interacted with ERalpha and ERbeta both in vitro and in mammalian cells in a ligand-independent fashion. NFAT3 bound specifically to the ERbeta region containing the activation function-1 domain, a ligand-independent transactivation domain. Overexpression of NFAT3 enhanced both ERalpha and ERbeta transcriptional activities in a ligand-independent manner and up-regulated downstream estrogen-responsive genes including pS2 and cathepsin D. Reduction of endogenous NFAT3 with NFAT3 small interfering RNA or overexpression of NFAT3 deletion mutants that lack the ER-binding sites reduced the NFAT3 coactivation of ERalpha and ERbeta. NFAT3 increased binding of ERalpha to the estrogen-responsive element and was recruited to endogenous estrogen-responsive promoters. NFAT3 was expressed differentially in many breast cancer cell lines and overexpressed in a subset of breast cancer patients. Knockdown of endogenous NFAT3 reduced the growth of human breast cancer ZR75-1 cells in a ligand-independent manner. Taken together, these results suggest that NFAT3 may play important roles in ER signaling and represent a novel target for breast cancer therapy.

Human pescadillo induces large-scale chromatin unfolding

The human pescadillo gene encodes a protein with a BRCT domain. Pescadillo plays an important role in DNA synthesis, cell proliferation and transformation. Since BRCT domains have been shown to induce chromatin large-scale unfolding, we tested the role of Pescadillo in regulation of large-scale chromatin unfolding. To this end, we isolated the coding region of Pescadillo from human mammary MCF10A cells. Compared with the reported sequence, the isolated Pescadillo contains in-frame deletion from amino acid 580 to 582. Targeting the Pescadillo to an amplified, lac operator-containing chromosome region in the mammalian genome results in large-scale chromatin decondensation. This unfolding activity maps to the BRCT domain of Pescadillo. These data provide a new clue to understanding the vital role of Pescadillo.

Expression of tumour necrosis factor receptors by bronchoalveolar cells in hypersensitivity pneumonitis

Tumour necrosis factor receptors (TNFR) and the Fas receptor (FasR) have been implicated in the pathogenesis of interstitial lung diseases. The current authors examined the expression of TNFR-1, TNFR-2 and FasR by bronchoalveolar cells in hypersensitivity pneumonitis (HP). Cell surface receptor expression on bronchoalveolar lavage cells was analysed by immunocytochemistry in 11 HP patients, 11 idiopathic pulmonary fibrosis (IPF) patients and 10 controls. TNFR-1, TNFR-2 and FasR were expressed on a higher percentage of alveolar macrophages (AM) in HP compared with controls and IPF patients. TNFR-2 and FasR expression on lymphocytes was also higher in HP than in controls and in IPF. TNFR-1, TNFR-2 and FasR expression correlated positively with the percentage of lymphocytes, and negatively with the percentage of AM in HP. Expression of TNFR-1 on AM and TNFR-2 on lymphocytes correlated with the percentage of neutrophils in HP. In conclusion, this study shows evidence of altered expression of tumour necrosis factor superfamily receptors in hypersensitivity pneumonitis.

COBRA1 inhibits AP-1 transcriptional activity in transfected cells

Mutations in the breast cancer susceptibility gene (BRCA1) account for a significant proportion of hereditary breast and ovarian cancers. Cofactor of BRCA1 (COBRA1) was isolated as a BRCA1-interacting protein and exhibited a similar chromatin reorganizing activity to that of BRCA1. However, the biological role of COBRA1 remains largely unexplored. Here, we report that ectopic expression of COBRA1 inhibited activator protein 1 (AP-1) transcriptional activity in transfected cells in a dose-dependent manner, whereas reduction of endogenous COBRA1 with a small interfering RNA significantly enhanced AP-1-mediated transcriptional activation. COBRA1 physically interacted with the AP-1 family members, c-Jun and c-Fos, and the middle region of COBRA1 bound to c-Fos. Lack of c-Fos binding site in the COBRA1 completely abolished the COBRA1 inhibition of AP-1 trans-activation. These findings suggest that COBRA1 may directly modulate AP-1 pathway and, therefore, may play important roles in cell proliferation, differentiation, apoptosis, and oncogenesis.

Characterization of COBRA1 in human breast cancer cell lines using a new polyclonal antibody against COBRA1

Mutations in the breast cancer susceptibility gene BRCA1 predispose individuals to breast and ovarian cancers. Cofactor of BRCA1 (COBRA1), a novel protein, was isolated as a BRCA1-interacting protein. However, the role of COBRA1 in breast cancer is poorly understood. In this study, we demonstrate that COBRA1 mRNA was differentially expressed in breast cancer cell lines by semi-quantitative reverse transcription-polymerase chain PCR (RT-PCR). We developed a highly specific rabbit polyclonal anti-COBRA1 antibody using GST-COBRA1 fusion protein. In most cases, the levels of COBRA1 protein in breast cancer cell lines detected by Western blotting with the anti-COBRA1 antibody correlated with those of COBRA1 mRNA. Immunofluorescence analysis indicated that COBRA1 was a nuclear protein. Endogenously expressed COBRA1 interacted with the nuclear protein BRCA1 in human breast cancer cells. These data suggest that the COBRA1 antibody may be a useful tool to investigate functions of COBRA1 in cancers and that, like BRCA1, COBRA1 may regulate various nuclear events in breast cancer cells.

Prospective study of relationship between cytomegalovirus pneumonia and viral load in renal transplant recipients

The present study prospectively examined the relationship between cytomegalovirus interstitial pneumonia (CMV-IP) and viral load among 56 renal transplant recipients. We sought to identify the cutoff of viral load to predict CMV-IP. Blood samples were obtained weekly within the first 2 months and every second week during 2 to 6 months after kidney transplantations. A commercial real-time polymerase chain reaction (PCR)-method was applied to quantify CMV-DNA in plasma or in leukocytes. Among 54 renal transplant recipients who were analyzed for CMV-DNA in the blood (96.4%), 8 experienced CMV-IP (14.3%) and 2 died (3.6%). After kidney transplantation, CMV-DNA loads were near 0 in plasma before the week 4 and before the week 3 in leukocytes among both groups. From week 5 (week 4, in leukocytes), plasma CMV-DNA loads in the CMV-IP group increased, the peak value reached at week 8 in plasma and the week 9 in leukocytes. Whereas, the CMV-DNA loads both in plasma and in leukocytes in the non-CMV-IP group fluctuated at lower levels, those in plasma were significantly different between the 2 groups at the weeks 5, 7, and 9. For CMV-DNA in leukocytes, there were significant differences between 2 groups from week 6 to week 11. The present study demonstrated that dynamic determination of CMV-DNA may predict the occurrence of CMV-IP. Viral loads over 10(4) copies/mL plasma continuing for 3 weeks may serve as a cutoff to predict CMV-IP.

XBP-1 increases ERalpha transcriptional activity through regulation of large-scale chromatin unfolding

Human X box binding protein 1 (XBP-1) is a transcription factor essential for hepatocyte growth, the differentiation of plasma cells, and the unfolded protein response. Recently, we have demonstrated that two forms of XBP-1, XBP-1S, and XBP-1U, enhance estrogen receptor alpha (ERalpha)-dependent transcriptional activity in a ligand-independent manner. However, how XBP-1S and XBP-1U regulate ERalpha transcriptional activity remains unknown. Here, we report that XBP-1S and XBP-1U induce large-scale chromatin unfolding by targeting the XBP-1 proteins to an amplified, lac operator-containing chromosome region in mammalian cells. This unfolding activity maps to the transactivation domains of XBP-1S and XBP-1U. Wild-type XBP-1S and XBP-1U, but not the mutants that completely abolished the ERalpha transcriptional activation, increased the chromatin unfolding activity of ERalpha. These data identify a novel function of XBP-1 and suggest that regulation of large-scale chromatin unfolding by XBP-1 may be responsible for the enhancement of ERalpha transcriptional activity.

Expression of constitutively active Notch4 (Int-3) modulates myeloid proliferation and differentiation and promotes expansion of hematopoietic progenitors

The Notch family of transmembrane receptors has been implicated in the regulation of many developmental processes. In this study, we evaluated the role of Notch4 in immature hematopoietic progenitors by inducing, with retroviral transduction, enforced expression of Int-3, the oncogenic and constitutively active form of mouse Notch4. Int-3-transduced human myeloid leukemia (HL-60) cells demonstrated significantly delayed expression of differentiation markers following retinoic acid and 12-0-tetradecanoylphorbol 13-acetate treatment. Furthermore, HL-60 cells expressing Int-3 displayed a slower growth rate than cells infected with void virus, and accumulation in the G0/G1 phases of cell cycle. Transduction with deletion mutants of Int-3 defined the importance of individual domains of the protein (in particular, the ANK domain and the C-terminal domain) in the inhibition of differentiation and growth arrest of HL-60 cells. When mouse bone marrow enriched for stem cells (5-fluorouracil-resistant, lineage negative) was transduced and cultured for two weeks, the Int-3-transduced population displayed a lower expression of differentiation markers and a three- to five-fold higher frequency of colony-forming cells (CFU-GM/BFU-E) than control cultures. These results strongly support the notion that Notch signaling inhibits differentiation and promotes expansion of hematopoietic stem/progenitor cells.

Regulation of large-scale chromatin unfolding by Smad4

The tumor suppressor Smad4 plays a critical role in the transforming growth factor-beta (TGF-beta signaling pathway. Smad4 is an essential component of transcriptional complexes mediating the activation of Smad-dependent target genes. However, how Smad4 regulates various chromosomal events remains unknown. Here, we report that Smad4 induces large-scale chromatin unfolding by targeting Smad4 to an amplified, lac operator-containing chromosome region in mammalian cells. This unfolding activity maps to the subdomains within the transactivation domain of Smad4. Both the N-terminal missense and the C-terminal truncated tumor-derived mutations increased the chromatin unfolding activity of Smad4. These data identify a novel function of Smad4 and suggest that regulation of large-scale chromatin unfolding by Smad4 may be responsible for cancer development.

Construction of two BAC libraries from the wild Mexican diploid potato, Solanum pinnatisectum, and the identification of clones near the late blight and Colorado potato beetle resistance loci

To facilitate isolation and characterization of disease and insect resistance genes important to potato, two bacterial artificial chromosome (BAC) libraries were constructed from genomic DNA of the Mexican wild diploid species, Solanum pinnatisectum, which carries high levels of resistance to the most important potato pathogen and pest, the late blight and the Colorado potato beetle (CPB). One of the libraries was constructed from the DNA, partially digested with BamHI, and it consists of 40328 clones with an average insert size of 125 kb. The other library was constructed from the DNA partially digested with EcoRI, and it consists of 17280 clones with an average insert size of 135 kb. The two libraries, together, represent approximately six equivalents of the wild potato haploid genome. Both libraries were evaluated for contamination with organellar DNA sequences and were shown to have a very low percentage (0.65-0.91%) of clones derived from the chloroplast genome. High-density filters, prepared from the two libraries, were screened with ten restriction fragment length polymorphism (RFLP) markers linked to the resistance genes for late blight, CPB, Verticillium wilt and potato cyst nematodes, and the gene Sr1 for the self-incompatibility S-locus. Thirty nine positive clones were identified and at least two positive BAC clones were detected for each RFLP marker. Four markers that are linked to the late blight resistance gene Rpi1 hybridized to 14 BAC clones. Fifteen BAC clones were shown to harbor the PPO (polyphenol oxidase) locus for the CPB resistance by three RFLP probes. Two RFLP markers detected five BAC clones that were linked to the Sr1 gene for self-incompatibility. These results agree with the library's predicted extent of coverage of the potato genome, and indicated that the libraries are useful resources for the molecular isolation of disease and insect resistance genes, as well as other economically important genes in the wild potato species. The development of the two potato BAC libraries provides a starting point, and landmarks for BAC contig construction and chromosome walking towards the map-based cloning of agronomically important target genes in the species.

Retinoic acid fails to reverse emphysema in adult mouse models

BACKGROUND

Previous work has shown that all-trans-retinoic acid reverses elastase induced emphysema in rats. Since there is currently no effective treatment for pulmonary emphysema, the effect of retinoic acid should be further investigated in other adult species. A study was undertaken using two murine models of emphysema to evaluate the effect of retinoic acid.

METHODS

The models used were an elastase induced emphysema model for acute alveolar destruction and a tumour necrosis factor (TNF)-alpha transgenic mouse which exhibits chronic air space enlargement, loss of elastic recoil, increased lung volume, and pulmonary hypertension comparable to human pulmonary emphysema. All-trans-retinoic acid (2 mg/kg) was injected for 12 successive days after the establishment of emphysema. The effects of treatment were evaluated using physiological and morphometric analyses.

RESULTS

In contrast to the rat, administration of all-trans-retinoic acid in these murine models did not improve the emphysema. Moreover, worsening of emphysema was observed in TNF-alpha transgenic mice treated with all-trans-retinoic acid. The level of keratinocyte chemoattractant (KC), a CXC chemokine, in bronchoalveolar lavage fluid was increased in TNF-alpha transgenic mice following retinoic acid treatment. These data raise the possibility that retinoic acid causes deterioration of emphysema by promoting inflammation in this model.

CONCLUSIONS

In these models, retinoic acid did not show positive effects on emphysema. The effect of retinoic acid in the treatment of pulmonary emphysema remains controversial, and further studies are required to determine its physiological effects under a variety of experimental conditions.

Restoration of dystrophin expression in mdx mice by intravascular injection of naked DNA containing full-length dystrophin cDNA

Duchenne muscular dystrophy (DMD) is a lethal, X-linked, recessive disease caused by a defect in the dystrophin gene. No effective therapy is available. Dystrophin gene transfer to skeletal muscle has been proposed as a treatment for DMD. However, successful treatment for DMD requires restoration of dystrophin in the affected muscle fibers to at least 20% of the normal level. Current gene transfer methods such as intramuscular injection of viral vector or naked DNA can only transfect a small area of muscle, and therefore is of little clinical utility. We have developed a semisystemic method for gene transfer into skeletal muscle of mdx mice, an animal model for DMD. Naked DNA was injected through the tail artery or vein of mice, in which the aorta and the vena cava were clamped at the location just below the kidneys. The DNA solution was thus forced into the blood vessels of both legs. Luciferase gene expression was detected in all muscle groups in both legs. The effects of injection speed, injection volume, and ischemia time on gene expression were also optimized. LacZ staining was used to check the spread of gene expression in muscle. Although the percentage of transfected fibers was modest (approximately 10%), beta-galactosidase was found in all muscle groups of both legs. Finally, plasmid DNA encoding full-length dystrophin gene was injected into mdx mice and widespread restoration of dystrophin protein was observed in all muscles of both hind limbs. In conclusion, these results demonstrate that the semisystemic delivery of naked DNA is a potential approach towards the long-term goal of gene therapy for DMD.

BRCA1 interacts with FHL2 and enhances FHL2 transactivation function

Germ-line mutations in BRCA1 are associated with an increased lifetime risk of developing breast and/or ovarian tumors. The BRCA1 gene product is a 220-kDa protein that contains a tandem of two BRCA1 C-terminal (BRCT) domains required for transcription. In an attempt to understand how BRCA1 exerts its function through BRCT domains, we search for partners of the BRCT domains of BRCA1. Using the yeast two-hybrid system, we identified the four and a half LIM-only protein 2 (FHL2) as a novel BRCA1 interacting protein. We demonstrate that BRCA1 and FHL2 can physically associate in vitro, in yeast, and in human cells. BRCA1 interacted with FHL2 through its second BRCT domain and the interaction of FHL2 with BRCA1 requires the last three LIM domains of FHL2. BRCA1 enhanced FHL2-mediated transcriptional activity in transient transfections. Tumor-derived transactivation-deficient BRCA1 mutants showed a reduced ability to enhance transactivation by FHL2. Lack of BRCA1 binding sites in the FHL2 completely abolished the FHL2 transactivation function. Reverse transcription polymerase chain reaction analysis showed that FHL2 mRNA levels may be downregulated in many breast cancer cell lines. These results suggest that the BRCA1-FHL2 interaction may be involved in transcriptional regulation and play a significant role in cancer cell growth.

Ligand-independent activation of estrogen receptor alpha by XBP-1

The estrogen receptor (ER) is a member of a large superfamily of nuclear receptors that regulates the transcription of estrogen-responsive genes. Several recent studies have demonstrated that XBP-1 mRNA expression is associated with ERalpha status in breast tumors. However, the role of XBP-1 in ERalpha signaling remains to be elucidated. More recently, two forms of XBP-1 were identified due to its unconventional splicing. We refer to the spliced and unspliced forms of XBP-1 as XBP-1S and XBP-1U, respectively. Here, we report that XBP-1S and XBP-1U enhanced ERalpha-dependent transcriptional activity in a ligand-independent manner. XBP-1S had stronger activity than XBP-1U. The maximal effects of XBP-1S and XBP-1U on ERalpha transactivation were observed when they were co-expressed with full-length ERalpha. SRC-1, the p160 steroid receptor coactivator family member, synergized with XBP-1S or XBP-1U to potentiate ERalpha activity. XBP-1S and XBP-1U bound to the ERalpha both in vitro and in vivo in a ligand-independent fashion. XBP-1S and XBP-1U interacted with the ERalpha region containing the DNA-binding domain. The ERalpha-interacting regions on XBP-1S and XBP-1U have been mapped to two regions, including the N-terminal basic region leucine zipper domain (bZIP) and the C-terminal activation domain. The bZIP-deleted mutants of XBP-1S and XBP-1U completely abolished ERalpha transactivation by XBP-1S and XBP-1U. These findings suggest that XBP-1S and XBP-1U may directly modulate ERalpha signaling in both the absence and presence of estrogen and, therefore, may play important roles in the proliferation of normal and malignant estrogen-regulated tissues.

Deficiency of the cysteine protease cathepsin S impairs microvessel growth

During angiogenesis, microvascular endothelial cells (ECs) secrete proteinases that permit penetration of the vascular basement membrane as well as the interstitial extracellular matrix. This study tested the hypothesis that cathepsin S (Cat S) contributes to angiogenesis. Treatment of cultured ECs with inflammatory cytokines or angiogenic factors stimulated the expression of Cat S, whereas inhibition of Cat S activity reduced microtubule formation by impairing cell invasion. ECs from Cat S-deficient mice showed reduced collagenolytic activity and impaired invasion of collagens type I and IV. Cat S-deficient mice displayed defective microvessel development during wound repair. This abnormal angiogenesis occurred despite normal vascular endothelial growth factor and basic fibroblast growth factor levels, implying an essential role for extracellular matrix degradation by Cat S during microvessel formation. These results demonstrate a novel function of endothelium-derived Cat S in angiogenesis.

Structure of protein tyrosine phosphatase 1B in complex with inhibitors bearing two phosphotyrosine mimetics

Protein tyrosine phosphatases (PTPases) are signal-transducing enzymes that dephosphorylate intracellular proteins that have phosphorylated tyrosine residues. It has been demonstrated that protein tyrosine phosphatase 1B (PTP1B) is an attractive therapeutic target because of its involvement in regulating insulin sensitivity (Elcheby et al. Science 1999, 283, 1544-1548). The identification of a second binding site in PTP1B (Puius et al., Proc. Natl. Acad. Sci. U.S.A.1997, 94, 13420-13425) suggests a new strategy for inhibitor design, where appropriate compounds may be made to simultaneously occupy both binding sites to gain much higher affinity and selectivity. To test this hypothesis and gain further insights into the structural basis of inhibitor binding, we have determined the crystal structure of PTP1B complexed with two non-peptidyl inhibitors, 4 and 5, both of which contain two aryl difluoromethylenephosphonic acid groups, a nonhydrolyzable phosphate mimetic. The structures were determined and refined to 2.35 and 2.50 A resolution, respectively. Although one of the inhibitors seems to have satisfied the perceived requirement for dual binding, it did not bind both the active site and the adjacent noncatalytic binding site as expected. The second or distal phosphonate group instead extends into the solvent and makes water-mediated interactions with Arg-47. The selectivity of the more potent of these two inhibitors, as well as four other inhibitors bearing two such phosphate mimetics for PTP1B versus seven other PTPases, was examined. In general, selectivity was modest to good when compared to PTPases Cdc25a, PTPmeg-1, PTPbeta, and CD45. However, selectivity was generally poor when compared to other PTPases such as SHP-1, SHP-2, and especially TCPTP, for which almost no selectivity was found. The implications these results have concerning the utility of dual-binding inhibitors are discussed.

BRCA1-induced large-scale chromatin unfolding and allele-specific effects of cancer-predisposing mutations

The breast cancer susceptibility gene BRCA1 encodes a protein that has been implicated in multiple nuclear functions, including transcription and DNA repair. The multifunctional nature of BRCA1 has raised the possibility that the polypeptide may regulate various nuclear processes via a common underlying mechanism such as chromatin remodeling. However, to date, no direct evidence exists in mammalian cells for BRCA1-mediated changes in either local or large-scale chromatin structure. Here we show that targeting BRCA1 to an amplified, lac operator-containing chromosome region in the mammalian genome results in large-scale chromatin decondensation. This unfolding activity is independently conferred by three subdomains within the transactivation domain of BRCA1, namely activation domain 1, and the two BRCA1 COOH terminus (BRCT) repeats. In addition, we demonstrate a similar chromatin unfolding activity associated with the transactivation domains of E2F1 and tumor suppressor p53. However, unlike E2F1 and p53, BRCT-mediated chromatin unfolding is not accompanied by histone hyperacetylation. Cancer-predisposing mutations of BRCA1 display an allele-specific effect on chromatin unfolding: 5' mutations that result in gross truncation of the protein abolish the chromatin unfolding activity, whereas those in the 3' region of the gene markedly enhance this activity. A novel cofactor of BRCA1 (COBRA1) is recruited to the chromosome site by the first BRCT repeat of BRCA1, and is itself sufficient to induce chromatin unfolding. BRCA1 mutations that enhance chromatin unfolding also increase its affinity for, and recruitment of, COBRA1. These results indicate that reorganization of higher levels of chromatin structure is an important regulated step in BRCA1-mediated nuclear functions.

[Production of vitamin C precursor--2-keto-L-gulonic acid from D-sorbitol by mixed culture of microorganisms]

Gluconobacter oxydans SCB329 only produce a little amount of 2-Keto-L-gulonic acid(2-KLG) from D-Sorbitol when growing alone; while Gluconobacter sp. SCB110 can transform D-Sorbitol to L-Sorbose and can not produce 2-KLG. 2-Keto-L-gulonic acid, the precursor of L-Ascorbic acid (Vitamin C) synthesis, was prepared directly with a high efficiency from D-Sorbitol by mixed culture of microorganism, which comprised Gluconobacter sp. SCB110 and Gluconobacter oxydans SCB329. The fermentation product from the mixed culture broth in the D-Sorbotol-containing medium was identified as 2-Keto-L-gulonic acid by HPLC, elementary analysis and infra-red adsorption spectrum.

[Clinical evaluation on second stage reconstruction for laryngostenosis after partial laryngectomy for laryngeal cancer patients]

OBJECTIVE

To present a new method of decannulation for laryngostenosis patients after partial laryngectomy and extended partial laryngectomy, and restoration of the essential functions of larynx and normal neck appearance.

METHODS

Nineteen cases of laryngostenosis after partial laryngectomy and extended partial laryngectomy were treated with second stage reconstruction. The patients had been treated by vertical laryngectomy (6/19) using extended vertical laryngectomy (11/19) and frontolateral laryngectomy (2/19). Among these patients, second stage reconstruction of larynx was performed by using rotary door myocutaneous flap (17/19). Stemohyoideus flap (1/19) and sternocleidomastoid flap (1/19).

RESULTS

Three and five year-survival rates were 91.7% (11/12) and 3/5, respectively. Over-all decannulation rate was 84.2% (16/19), but 94.1% (16/17) in patients with rotary door myocutaneous flap and 0% (0/2) in both patients with sternohyoideus flap and sternocleidomastoid flap. There were 3 decannulation failures (15.8%). All patients resumed acceptable voice, 94.7% (18/19) enjoyed satisfactory phonation, but 5.3% (1/19) showed severe hoarseness. All except 2 patients returned normal swallow function. The latter 2 patients experienced mild abnormal swallow during eating fluid food in early stage of surgery, but had normal swallow function after 1-2 weeks.

CONCLUSION

Functional laryngectomy is a radical operation in selected cases with advanced laryngeal cancer. The second stage reconstruction with bi-pedical rotary door myocutaneous flaps can help decannulation in patients who developed laryngostenosis after partial laryngectomy and extended partial laryngectomy, and restore the essential function of larynx and normal neck appearance.

Inhibition of growth and cell cycle arrest of ARCaP human prostate cancer cells by ectopic expression of ER-alpha

The estrogen receptor-alpha (ER-alpha) is a ligand-dependent transcription factor that regulates the growth, differentiation, and development of hormone-responsive target organs. While ER-alpha has been reported to play critical role in the pathogenesis and prognosis of breast and prostate cancers, its possible functional role in regulating prostate cancer cell growth in a ligand-dependent or -independent manner is poorly understood. We addressed this question by stably transfecting wild type (wt) ER-alpha cDNA into an invasive estrogen receptor-negative human prostate cancer cell line ARCaP. We isolated several clonal lines of transfected cells expressing varying levels of ER-alpha. The ectopic expression of wt ER-a markedly inhibited the growth of ARCaP cells in vitro in an ER-a dose-dependent but ligand-independent manner. Flow cytometric analysis of the wt ER-alpha-transfected ARCaP cells revealed that wt ER-alpha expression arrested cell growth in G1 phase. Our results suggest that ER-alpha may regulate prostate cell growth and participate in the pathogenesis of prostate cancer. ER-alpha may be delivered and expressed ectopically to target prostate cancer progression.

USPIO-enhanced dynamic MRI: evaluation of normal and transplanted rat kidneys

To evaluate first-pass renal perfusion with ultrasmall superparamagnetic iron oxide (USPIO) particles by MRI, 40 normal rats (20 Dark Agouti (DA) rats and 20 Brown Norway (BN) rats) and 16 transplanted rats (12 allografts and four isografts) were studied on day 4 post-transplantation with different USPIO doses (3.0-18.1 mg Fe/kg/body weight). All animals underwent 128 consecutive snapshot fast low-angle shot (FLASH) coronal dynamic studies in 43 s. In the normal rats, a larger maximum signal decrease (MSD) in the cortex and the outer medulla is observed with an increasing dose of USPIO particles (P < 0.01). No significant differences were observed between the right and left kidneys at all doses studied. Higher MSD, time of occurrence of MSD (tMSD), and wash-in slope appear with higher doses of USPIO particles. The dynamic curves for DA rats show similar shapes when compared to those for BN rats. In the transplanted rats, allograft kidneys show lower MSD, longer tMSD, and lower wash-in slope compared to those in the normal kidneys. Isograft kidneys show perfusion patterns similar to those of normal kidneys in the cortex and the outer medulla. Histopathology indicates acute vascular rejection in all allografts and normal kidney architecture in all isografts. The results clearly show good agreement between the renal graft perfusion measurements and histopathological changes associated with rejection. This work also introduces a new signal analysis methodology for the automatic detection of transplanted organ rejection. This method compares the dynamics of the intrarenal signal intensities for native and transplanted kidneys. A quantitative measurement to detect significant differences between these signals was developed, and showed that this technique exhibits good performance in identifying renal rejection.

[Clinical application of TRAFIX internal fixation system in correction of scoliosis]

OBJECTIVE

To evaluate the results of TRAFIX internal fixation system in correction of adolescent scoliosis.

METHODS

From October 1997 to June 1999, 27 patients with idiopathic scoliosis received spinal instrumentation with TRAFIX system. Their average age was 14.2 years (from 11 to 21). Four patients of the 27 underwent anterior release, while 1 patient accepted revision approach. The average follow up time was 26 months (13-37 months).

RESULTS

The measurements for primary coronal deformity before and after surgery were 65 degrees (42 degrees-110 degrees) and 29.2 degrees (3 degrees-64 degrees) respectively. The average curve correction was 55.4%. The average fused segments were 11.5 vertebrae. The distance between the center of apex and C7 plumb line was 52.1 mm before operation (25-94 mm) and 28.5 mm after surgery (4-62 mm).

CONCLUSION

The TRAFIX internal fixation system provides three-dimensional correction with refinement, convenient and reliable fixation.

[Study of calcium buffer in SH-SY5Y cells]

AIM

To study the calcium buffer in SH-SY5Y cells.

METHODS

By using patch clamp technique, measure voltage-gated calcium currents in undifferentiated SH-SY5Y cell line. Then, by using microfluorometric technique, detect the intracellular [Ca2+]i and the dynamic recovery course after high-K+ induced [Ca2+]i elevation.

RESULTS

There are voltage-gated calcium currents in undifferentiated SH-SYSY cell line. When the time intervals between the stimulus are < 150s, the recovery course will be much more deferred because of the saturation of the intracellular calcium buffer; and when the intervals between the stimulus are > 150 s, the buffer will recruit so as to lead to the steadiness state of the recover course.

CONCLUSION

Calcium buffer proteins have an important effect in the course of cellular calcium signal transduction.