Claudin-1 expression decreases with increasing pathological grade in actinic keratosis and may be a marker of high-risk actinic keratosis

BACKGROUND

Actinic keratosis (AK) is a common sun-induced skin disorder that can progress to invasive squamous cell carcinoma. However, there is still no reliable method to predict high-risk AK.

AIM

To identify markers that reflect the biological behaviour of AK and to understand the pathogenesis of AK.

METHODS

In total, 52 patients with AK and 17 site-matched healthy controls (HCs) were enrolled. We evaluated solar elastosis and immunohistochemical features using antibodies to p53, vitamin D receptor (VDR), claudin-1 and Langerin (CD207). Comparisons between AK and HC skin were performed and analyses carried out according to the pathological grade of AK.

RESULTS

We found that in both patients and HCs, solar elastosis increased and Langerhans cell (LC) density decreased with ageing. Solar elastosis and p53 expression were higher and VDR expression was lower in patients than in HCs; however, there was no statistical difference between them in relation to the pathological grade of AK. Claudin-1 expression gradually decreased from HC skin to severe AK, and particularly decreased in areas with epidermal atypia. LC density in severe AK was significantly lower than in HC skin and mild AK, while there was no difference in LC density between HC skin, mild AK and moderate AK.

CONCLUSIONS

Claudin-1 could be a useful marker of the pathological severity of AK. In addition, p53 increases and VDR decreases in AK, not in a gradual manner but in the early steps of carcinogenesis. LC density is relatively maintained in AK until it reaches severe dysplasia.

The Reliability of Histoculture Drug Response Assay (HDRA) in Chemosensitivity Tests for Breast Cancer

PURPOSE

Cancers are highly individual in their response to chemotherapy, however attempts to predict tumor response to drugs using in vitro cell culture have largely failed. A new technology, the histoculture drug response assay (HDRA), appears to have solved many previous problems. The purpose of this study is to evaluate the reliability of HDRA in a chemosensitivity test for breast cancer.

MATERIALS AND METHODS

Tumor specimens from breast cancer patients were evaluated by HDRA using different chemotherapeutic agents. Each specimen was tested using a blind method in order to determine the reproducibility of HDRA results for the same tissue and with a triplicated assay in order to determine reproducibility by different examiners. The evaluative power of this assay and the chemosensitivity of drugs for each specimen was determined.

RESULTS

Specimens of 92.9% (65/70) were successfully cultured and evaluated for chemosensitivity. The reproducibility of HDRA for the same tissue was 75% (100% agreement) and 100% (over 70% agreement), respectively. And the reproducibility by different examiners was 78.9% (100% agreement) and 94.7% (over 70% agreement), respectively. Each specimen demonstrated a response to at least one agent.

CONCLUSION

The evaluative power and reproducibility of HDRA were high, therefore it might serve as a reliable clinical method for chemosensitivity testing. However, there is a need for clinical trial in which patients are initially randomized for treatment either by HDRA direction or by clinician's choice.

A case of perforating dermatofibroma with floret-like giant cells

Dermatofibromas are slow-growing solitary nodules, composed mostly of a dermal proliferation of spindle cells and epithelioid cells. Some dermatofibromas present with multinucleated giant cells, such as Touton, foreign body, and osteoclast-like cells. We report a case of dermatofibroma containing both Touton giant cells and floret-type cells. A 12-year-old boy presented with a 6-mm, firm, nontender, dusky-red to greyish dermal nodule on his left popliteal fossa. As suggested clinically by the central opening, perforation of the epidermis with partial extrusion of the dermal components, including macrophages and vertically oriented collagen bundles, via transepidermal elimination, were detected. In the upper dermis, collagen trapping and mostly epithelioid cells with many giant cells were seen, while the lower part contained mainly spindle cells in a storiform pattern. Multinucleated giant cells scattered in the upper dermis were mainly floret-type multinucleated giant cells with star-shaped cytoplasmic projections, associated with some Touton giant cells. To our knowledge, this is the first report of a perforating dermatofibroma with floret-type multinucleated giant cells.

Enhanced Anti-Cancer Effect of Snake Venom Activated NK Cells on Lung Cancer Cells by Inactivation of NF-κB

In the present study, we investigated anti-cancer effect of snake venom activated NK cells (NK-92MI) in lung cancer cell lines. We used snake venom (4 μg/ml) treated NK-92MI cells to co-culture with lung cancer cells. There was a further decrease in cancer cell growth up to 65% and 70% in A549 and NCI-H460 cell lines respectively, whereas 30–40% was decreased in cancer cell growth by snake venom or NK-92MI alone treatment. We further found that the expression of various apoptotic proteins such as that Bax, and cleaved caspase-3 as well as the expression of various death receptor proteins like DR3, DR4 and Fas was also further increased. Moreover, consistent with cancer cell growth inhibition, the DNA binding activity of NF-κB was also further inhibited after treatment of snake venom activated NK-92MI cells. Thus, the present data showed that activated NK cells could further inhibit lung cancer cell growth.

Modulation of the murine microbiome with a concomitant anti-obesity effect by Lactobacillus rhamnosus GG and Lactobacillus sakei NR28

The microbiota of the gastrointestinal tract (GIT) constitutes the major part of the total human microbiome and is considered to be an important regulator of human health and host metabolism. Numerous investigations in recent years have focused on the connection between the human microbiota and metabolic diseases such as obesity, type II diabetes and atherosclerosis. Yet, little is known about the impact of probiotic consumption on the GIT microbial population and the potential effect on chronic diseases. In this study, the modulation of the microbial community in the murine small intestine resulting from probiotic feeding was investigated and was found to be associated with an anti-obesity effect. Changes in the microbiota of the mouse faeces and small intestine were monitored using quantitative real-time PCR and by following the mRNA expression levels of various obesity-related biomarkers following probiotic feeding in a mouse model. Lactobacillus rhamnosus GG and Lactobacillus sakei NR28 (a putative probiotic strain isolated from kimchi) were administered at a daily level of approximately 1×10(8) viable bacteria per mouse (C57BL/6J mice) for up to three weeks. Feeding these strains resulted in a significant reduction of epididymal fat mass, as well as obesity-related biomarkers like acetyl-CoA carboxylase, fatty acid synthase, and stearoyl-CoA desaturase-1 in the liver. The total number and ratio of the microbial groups, i.e. Firmicutes, Bacteroidetes, Clostridium cluster I and XIVab, and Lactobacillus spp. were modulated in the small intestine, and the Firmicutes:Bacteroidetes ratio was decreased. In contrast, no noticeable effect of probiotic feeding could be detected on the faecal microbiota, neither quantitatively, nor with regard to the bacterial groups (Firmicutes, Bacteroidetes, Clostridium cluster I and XIVab, and Lactobacillus spp.) studied.

Role of FK506 binding proteins in neurodegenerative disorders

Protein misfolding has been implicated in the pathophysiology of several neurodegenerative 'amyloidoses' that includes Alzheimer's, Parkinson's, Huntington's disease, frontotemporal dementia and amyotrophic lateral sclerosis. Accumulation of misfolded proteins into ordered fibrillar intra- or extracellular amyloids results in brain lesions that in turn lead to injury and neuronal loss. The appearance of protein aggregates in the diseased brain hints at an inability of cellular chaperones to properly assist folding of client proteins. Not surprisingly, studies involving cell-based and animal models of the neurodegenerative diseases have shown that overexpression of molecular chaperones can provide neuroprotection. Together with identification of new targets for symptomatic relief of motor and non-motor defects in neurodegenerative disorders, there is a critical unmet clinical need for the development of novel neuroprotective molecules. One such promising class of compounds are neuroimmunophilin ligands (NILs). Derived from FK506 (tacrolimus), NILs have been shown to be efficacious in a number of neurodegenerative disorders. The ability of these nonimmunosuppressive NILs to protect neurons is modulated, in part, by a large family of co-chaperone proteins called the FK506 binding proteins (FKBPs). This review focuses on the roles of FKBPs in neurodegenerative disorders with an emphasis on the cellular mechanisms responsible for their neuroprotective and neurotrophic activities. We discuss the structural features of FKBPs and the mode of action of NILs. For brevity, we limit our discussion to those FKBPs that are particularly enriched in the nervous system. We hope that such information will aid in the rational design of new and improved NILs for ameliorating neurodegenerative disorders.

A tunable 3D optofluidic waveguide dye laser via two centrifugal Dean flow streams

This paper presents a tunable optofluidic waveguide dye laser utilizing two centrifugal Dean flows. The centrifugal Dean flow increases the light confinement of the dye laser by shaping a three-dimensional (3D) liquid waveguide from curved microchannels. The active medium with the laser dye is dissolved in the liquid core and pumped with an external pump laser to produce stimulated emission. The laser's Fabry-Pérot microcavity is formed with a pair of aligned gold-coated fiber facets to amplify the fluorescent emission. The advantage of the 3D optofluidic waveguide dye laser is its higher efficiency, thus to obtain lasing at a reduced threshold (60%) with higher output energy. The demonstrated slope efficiency is at least 3-fold higher than its traditional two-dimensional equivalent. In addition, the laser output energy can be varied on demand by tuning the flow rates of the two flows. This technique provides a versatile platform for high potential applications microfluidic biosensor and bioanalysis.

Degradation of organic dye using zero-valent iron prepared from by-product of pickling line

In this study, zero-valent iron (ZVI) was produced using iron oxide that is a by-product of a pickling line at a steel works. The reaction activity of the produced ZVI was evaluated through a series of decomposition experiments of Orange II aqueous solution. The size of ZVI particles increased with reduction temperature due to coalescence. Correspondingly, the specific surface area of ZVI decreased with increasing reduction temperature. The decomposition efficiency of synthesized ZVI particles was higher at a lower pH. In particular, no significant decomposition reaction was observed at pH of 4 and higher. The rate of the ZVI-assisted decomposition of Orange II was increased by addition of H2O2 at pH of 3, whereas it was reduced by addition of H2O2 at a higher pH of 6. Nevertheless, simultaneous use of ZVI, UV and H2O2 led to a considerable increase in the decomposition rate even at a high pH condition (pH = 6).

Biochip array-based analysis of plasma cytokines in HIV patients with immunological and virological discordance

Assessment of cytokines in body fluids or cells provides important information in understanding the disease process and designing treatment strategies. Recent introduction of antibody-based protein arrays have provided investigators simultaneous and specific detection of multiple analytes in a single sample using minimum volumes. In this study, we used a biochip array system capable of measuring 12 cytokines and growth factors (IL-2, IL-4, IL-6, IL-8, IL-10, IL-1alpha, IL-1beta, IFN-gamma, TNF-alpha, monocyte chemoattractant protein-1 (MCP-1), vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF)) in HIV patients with immunological and virological discordance (discordant) to find out differences if any, in their plasma cytokine profiles when compared with concordant HIV-infected individuals. A sandwich chemiluminescent assay was performed with plasma specimens of 110 HIV patients (55 discordant, 55 concordant) and 22 normal healthy individuals followed by enzyme-linked immunosorbent assay (ELISA) to the confirm levels of cytokines and growth factors that showed significant differences in the two groups. The discordant HIV patients showed significantly higher levels of plasma VEGF (P = 0.001) and EGF (P = 0.034) levels when compared with concordant patients. Overall, the patients showed significantly higher levels of TNF-alpha, MCP-1 and VEGF when compared with the normal healthy controls (P < 0.05). ELISA for VEGF (P < 0.001) and EGF (P = 0.004) confirmed the comparison obtained with biochip array, between the discordant and concordant patients. The results of cytokine quantitation by biochip array and ELISA confirmed that this technology is not only comparable but also has a good potential in the future applications involving measurement of multiple cytokines with limiting specimens.

Novel electronic structure of inhomogeneous quantum wires on a Si surface

A one-dimensional system of Si(111)-(5 x 2)-Au is explored using scanning tunneling microscopy and spectroscopy. The chain of Si adatoms called bright protrusions (BP's) is found to be semiconducting with an evanescent state in the gap, which originates from adjoining metallic BP-free segments. A quantitative analysis shows that the evanescent state decays in inverse-Gaussian form, leading to an appearance of a parabolic BP chain, and scales to its chain length. Spatial decay of the state suggests a quadratic band bending and the existence of a Schottky-like potential barrier at the interface driven by charge transfer.

Metal-insulator transition in Au atomic chains on Si with two proximal bands

One-dimensional atomic chains on Au/Si(557) feature two proximal 1D bands near the Fermi level, which were controversially attributed as a spinon-holon pair of a Luttinger liquid. Angle-resolved photoemission shows that only one band is metallic with the neighboring one gapped at room temperature. Furthermore, even the metallic branch is found to undergo a metal-insulator transition upon cooling, which follows a mean-field-type behavior. Scanning tunneling microscopy observes two apparently unequivocal chains on the surface, one of which exhibits periodicity doubling accompanying the metal-insulator transition. The surface 1D structure is thus concluded to be insulating at low temperature with a Peierls-type instability.

Phylogeny of Alariaceae, Laminariaceae, and Lessoniaceae (Phaeophyceae) based on plastid-encoded RuBisCo spacer and nuclear-encoded ITS sequence comparisons

Concatenated sequences from the plastid-encoded RuBisCo spacer and nuclear-encoded rDNA ITS region of the Alariaceae, Laminariaceae, and Lessoniaceae as currently recognized were used to determine the phylogeny of kelps (Phaeophyceae). Our analyses indicate that all taxa in the Alariaceae, Laminariaceae, and Lessoniaceae form a monophyletic lineage (the Laminariales sensu stricto). The phylogenetic analyses show that the kelps form eight well-supported clades (represented by Egregia, Laminaria, Hedophyllum, Macrocystis, Alaria, Agarum, Ecklonia, and Lessonia) that conform to the tribes of the current morphological classification system of the "advanced" kelps. Our results suggest that the kelps should be classified into eight families rather than the three that are presently used. The interrelationships among the eight lineages were, however, unresolved in the phylogenetic analyses. In all trees, Egregia diverged first and is the sister to the other kelp taxa. Our phylogenetic analyses also indicate that Kjellmaniella and Laminaria do not form a monophyletic group. Taken together, the RuBisCo spacer and rDNA ITS prove useful for understanding the evolutionary history of the advanced kelps and provide a new framework for establishing the systematics of these commercially important brown algae.

Phosphatidylinositol 3-kinase regulates proliferation of RAW 264.7 macrophages

Phosphatidylinositol 3-kinase (P13-kinase) is an enzyme that acts as a direct biochemical link between a novel phosphatidylinositol pathway and a number of proteins containing intrinsic or associated kinase activities. Here we demonstrate that wortmannin, P13-kinase inhibitor, decreases the proliferation of RAW 264.7 macrophages and that another structurally unrelated inhibitor of P13-kinase, LY294002. also inhibits the proliferation. These results indicate a possible involvement of P13-kinase in RAW 264.7 macrophages growth regulation. Wortmannin stimulation of RAW 264.7 macrophages is followed by sustained expression of the mRNA of c-fos and a transient expression of the mRNA of c-jun. We also show that the wortmannin and LY294002 induce a cell cycle arrest in asynchronously growing cells leading to an inhibition of cell proliferation after 12 h of treatment. In addition, wortmannin or LY294002 inhibited the phorbol 12-myristate 13-acetate-induced macrophages proliferation potently. These results suggest that P13-kinase plays an important role in growth regulation of RAW 264.7 macrophages and that protein kinase C is a down stream effector of P13-kinase.

Compaction in preimplantation mouse embryos is regulated by a cytoplasmic regulatory factor that alters between 1- and 2-cell stages in a concentration-dependent manner

Present studies were performed to investigate what factors affect the morphogenesis of preimplantation mouse embryos, and to find the action mechanism of that factor by using cytoplasm removal and its reconstitution from a different developmental stage embryo. Half (HP group) or one-third of cytoplasm (TP group) was removed from 1-cell mouse embryos by micromanipulation, and their morphogenesis and genome expression were compared with sham-operated embryos (SP group). The compaction and blastocoel formation of embryos in both the HP and TP groups were accelerated in time and cell stage when compared with those of the SP group. However, the total activity and time of RNA synthesis, and gene expression of ZO-1alpha+ isoform were not different. To change the cytoplasm composition without altering the nucleus/cytoplasmic ratio, half a 1-cell embryo with both pronuclei was reconstituted with the half enucleated cytoplasm of 1-cell embryo (P + P group), 2-cell (P + 2 group) or 4-cell (P + 4 group) by electrofusion. Embryonic compaction, timing of RNA synthesis, and stage-specific gene expression of the ZO-1alpha(+) isoform in the P + 2 and P + 4 groups were accelerated in time and cell stage than that in the P + P group, but not different between the P + 2 and P + 4 groups. In addition, a blastomere of 2-cell embryo was reconstituted with the enucleated cytoplasm of 1-cell embryo (2 + P group) or 2-cell (2 + 2 group) in equal volume by electrofusion. Also, the karyoplast of 2-cell was fused with the enucleated 1-cell embryo (2 + PP group). Embryonic development, total activity of RNA synthesis, and gene expression of the ZO-1alpha(+) isoform of embryos in the 2 + P and 2 + PP groups were delayed when compared with those of the 2 + 2 group. Also, the phenomena of compaction and blastocoel formation were delayed in the development time and cell stage. From these results, the nucleus/cytoplasm ratio was found to have no direct effect on the regulation of embryonic morphogenesis, although it accelerated compaction and blastocoel formation. However, cytoplasmic factors that altered between 1- and 2-cell stages regulate embryonic morphogenesis, especially compaction, of preimplantation mouse embryos in concentration-dependent manner.

Ovarian expression of melatonin Mel(1a) receptor mRNA during mouse development

Melatonin, secreted by the pineal gland, is involved in the regulation of many physiological functions of various species of animals. In the present study, the expression of gene for melatonin Mel(1a) receptor (MelR) was evaluated in the ovary, hypothalamus, and pituitary according to the developmental stages in female mice. Semiquantitative reverse-transcription polymerase chain reaction (RT-PCR) and in situ PCR techniques were applied. According to the developmental stages, gene for MelR was differently expressed on ovary, hypothalamus, and pituitary. MelR gene was first expressed on pituitary prior to the expression in hypothalamus and ovary. Ovarian MelR gene started to express at birth. Unlike hypothalamic expression of MelR gene which was identified after birth, in pituitary, it was expressed at 16 days post coitum. In the ovary, the expression signal of MelR gene was identified on granulosa cells. However, the signal was not detected in the theca cells. It was weak in the primordial and atretic follicles. Taken together, it can be considered that melatonin has a pivotal role in the folliculogenesis.

Synthetic bile acid derivatives induce nonapoptotic death of human retinal pigment epithelial cells

PURPOSE

To study whether the synthetic ursodeoxycholic acid (UDCA) and chenodeoxycholic acid (CDCA) derivatives, which we have synthesized and have reported their apoptosis-inducing effect, have the effect on the proliferation of retinal pigment epithelial cells.

METHODS

UDCA, CDCA, and their synthetic derivatives were administered in culture to the human retinal pigment cell line, ARPE-19. The effect on cell viability and growth was assessed by trypan blue dye exclusion. In order to evaluate the type of cell death, mitochondrial membrane potential assay, DNA electrophoresis, TUNEL assay, nuclear staining and Western blotting for caspase-3 and poly(ADP-ribose) polymerase (PARP) activities were conducted.

RESULTS

Unlike UDCA and CDCA, which did not exhibit a significant effect on viability, their synthetic derivatives decreased the viability of ARPE-19 cells in a concentration-dependent manner. The cells treated with the synthetic derivatives did not demonstrate the characteristic findings of apoptosis, such as DNA ladder, DNA fragmentation, nuclear condensation or fragmentation, and caspase-3 and PARP activation. The reduction of mitochondrial membrane potential was shown. In electron microscopical study nuclear condensation was not shown.

CONCLUSIONS

The synthetic UDCA and CDCA derivatives induced nonapoptotic death of ARPE-19 cells.

Transformation of kidney epithelial cells by a quinol thioether via inactivation of the tuberous sclerosis-2 tumor suppressor gene

Although hydroquinone (HQ) is a rodent carcinogen, because of its lack of mutagenicity in standard bacterial mutagenicity assays it is generally considered a nongenotoxic carcinogen. 2,3,5-Tris-(glutathion-S-yl)HQ (TGHQ) is a potent nephrotoxic metabolite of HQ that may play an important role in HQ-mediated nephrocarcinogenicity. TGHQ mediates cell injury by generating reactive oxygen species and covalently binding to tissue macromolecules. We determined the ability of HQ and TGHQ to induce cell transformation in primary renal epithelial cells derived from the Eker rat. Eker rats possess a germline inactivation of one allele of the tuberous sclerosis-2 (Tsc-2) tumor suppressor gene that predisposes the animals to renal cell carcinoma. Treatment of primary Eker rat renal epithelial cells with HQ (25 and 50 microM) or TGHQ (100 and 300 microM) induced 2- to 4-fold and 6- to 20-fold increases in cell transformation, respectively. Subsequently, three cell lines (The QT-RRE 1, 2, and 3) were established from TGHQ-induced transformed colonies. The QT-RRE cell lines exhibited a broad range of numerical cytogenetic alterations, loss of heterozygosity at the Tsc-2 gene locus, and loss of expression of tuberin, the protein encoded by the Tsc-2 gene. Only heterozygous (Tsc-2(EK/+)) kidney epithelial cells were susceptible to transformation by HQ and TGHQ, as wild-type cells (Tsc-2(+/+)) showed no increase in transformation frequency over background levels following chemical exposure. These data indicate that TGHQ and HQ are capable of directly transforming rat renal epithelial cells and that the Tsc-2 tumor suppressor gene is an important target of TGHQ-mediated renal epithelial cell transformation.

PatS and products of nitrogen fixation control heterocyst pattern

The filamentous cyanobacterium Anabaena sp. strain PCC 7120 forms a developmental pattern of single heterocysts separated by approximately 10 vegetative cells. Heterocysts differentiate from vegetative cells and are specialized for nitrogen fixation. The patS gene, which encodes a small peptide that inhibits heterocyst differentiation, is expressed in proheterocysts and plays a critical role in establishing the heterocyst pattern. Here we present further analysis of patS expression and heterocyst pattern formation. A patS-gfp reporter strain revealed clusters of patS-expressing cells during the early stage of heterocyst differentiation. PatS signaling is likely to be involved in the resolution of these clusters. Differentiating cells were inhibited by PatS during the time period 6 to 12 h after heterocyst induction, when groups of differentiating cells were being resolved to a single proheterocyst. Increased transcription of patS during development coincided with expression from a new transcription start site. In vegetative cells grown on nitrate, the 5' end of a transcript for patS was localized 314 bases upstream from the first translation initiation codon. After heterocyst induction, a new transcript with a 5' end at -39 bases replaced the vegetative cell transcript. A patS mutant grown for several days under nitrogen-fixing conditions showed partial restoration of the normal heterocyst pattern, presumably because of a gradient of nitrogen compounds supplied by the heterocysts. The patS mutant formed heterocysts when grown in the presence of nitrate but showed no nitrogenase activity and no obvious heterocyst pattern. We conclude that PatS and products of nitrogen fixation are the main signals determining the heterocyst pattern.

Solution structure of the antiapoptotic protein bcl-2

The structures of two isoforms of Bcl-2 that differ by two amino acids have been determined by NMR spectroscopy. Because wild-type Bcl-2 behaved poorly in solution, the structures were determined by using Bcl-2/Bcl-x(L) chimeras in which part of the putative unstructured loop of Bcl-2 was replaced with a shortened loop from Bcl-x(L). These chimeric proteins have a low pI compared with the wild-type protein and are soluble. The structures of the two Bcl-2 isoforms consist of 6 alpha-helices with a hydrophobic groove on the surface similar to that observed for the homologous protein, Bcl-x(L). Comparison of the Bcl-2 structures to that of Bcl-x(L) shows that although the overall fold is the same, there are differences in the structural topology and electrostatic potential of the binding groove. Although the structures of the two isoforms of Bcl-2 are virtually identical, differences were observed in the ability of the proteins to bind to a 25-residue peptide from the proapoptotic Bad protein and a 16-residue peptide from the proapoptotic Bak protein. These results suggest that there are subtle differences in the hydrophobic binding groove in Bcl-2 that may translate into differences in antiapoptotic activity for the two isoforms.

The effects of particle size distribution on the settleability of CSOs pollutants

Over the past decades, flocculation and/or sedimentation processes have been adopted to remove pollutants from CSOs. It has been learned that major factors affecting settlement of pollutants are the particle size distribution, their settling velocities and their specific gravity. It is, therefore, a good idea to analyze the particle size distribution and settleability of CSOs pollutants in order to develop details in designing a process. Discussed in this study are pollutant characteristics of CSOs such as particle size distribution and settleability of pollutants. The power law function is applied and is found to be an effective and reliable index for expressing the particle size distribution of pollutants in CSOs. Based on the particle size spectrum analysis, the tendency toward settling and simultaneous flocculation-settling phenomenon of CSOs pollutants is described. Based on the regression analysis it is observed that the derived constants of curves representing settling velocity profile are proportional to the initial concentration of particles and to the beta-values of power law distributions. It is also revealed that the simultaneous flocculation-settling processes are effectively described by the changes of the average particle diameter and of the beta-values of power law distributions.

Genistein induces apoptosis of RPE-J cells by opening mitochondrial PTP

Although previous studies demonstrated that genistein-induced apoptosis of various cell types including RPE-J cells, the involvement of mitochondrial events in such types of apoptosis has not been demonstrated to date. In this investigation of genistein-induced apoptosis of RPE-J cells, genistein induced the reduction of the mitochondrial membrane potential and the release of cytochrome c to cytosol. A mitochondrial permeability transition pore (PTP) blocker bongkrekic acid prevented the reduction of the mitochondrial membrane potential and cytochrome c release, and consequently abolished caspase-3 activation, nuclear condensation, and DNA fragmentation. On the other hand, zVAD-fmk did not inhibit the mitochondrial event such as the reduction of the mitochondrial membrane potential and cytochrome c release although it prevented caspase-3 activation, nuclear condensation, and DNA fragmentation. Taken together, genistein induces apoptosis of RPE-J cells by opening the mitochondrial PTP, and the mitochondrial event in this type of apoptosis is caused independently of caspase.

Genistein produces reduction in growth and induces apoptosis of rat RPE-J cells

PURPOSE

To investigate the effect of the tyrosine kinase inhibitor, genistein, on the growth of the retinal pigment epithelial (RPE) cell.

METHODS

The tyrosine kinase inhibitor, genistein, was administered in culture to the rat retinal pigment epithelial cell line, RPE-J. The effect on cell viability and growth was assessed by trypan blue dye exclusion. Induction of apoptosis was confirmed morphologically by light and electron microscopy and oligonucleosomal fragmentation was assessed by TUNEL and DNA ladder. Quantitation was undertaken by propidium iodide staining and photometric enzyme immunoassay. Western blot was performed to study poly-(ADP-ribose)-polymerase cleavage (PARP). To confirm the involvement of caspase, the caspase inhibitor z-VAD-fmk was employed. In addition, cell cycle phase was determined by flow cytometry.

RESULTS

We here demonstrate that genistein treatment of RPE-J cells produces a dose- and time-dependent growth inhibition. Genistein in higher concentration induces apoptosis of rat RPE-J cell. z-VAD-fmk inhibited this type of apoptosis and cleavage of PARP enzyme was demonstrated. Ten micromolar genistein inhibited cell proliferation by G(0)/G(1) arrest without inducing apoptosis of the major population. Whereas 50 microM genistein caused growth inhibition of RPE-J cells by G(2)/M arrest and subsequent apoptotic death.

CONCLUSIONS

Genistein inhibits RPE cell growth and induces apoptosis. The ability of genistein to inhibit the proliferation and to induce apoptosis of RPE cells could be potentially therapeutic for proliferative vitreoretinopathy.

Expression of protein kinase C genes in normal (+/+) and W mutant alleles (Wsh/Wsh, W/Wv) mice testes

In the present study, we investigated the expression of mRNA of protein kinase C (PKC) isoenzymes (alpha, beta, gamma, delta, epsilon, zeta, eta, and theta) in normal (+/+) and W mutant alleles mice testes. In +/+ mice testes, abundant expression of PKCdelta and PKCtheta was observed, while other PKCs (alpha, beta, gamma, epsilon, zeta, and eta) generally were not detected by Northern blotting. The PKCdelta and PKCtheta isoenzymes demonstrated a distinctive cellular distribution when evaluated by in situ hybridization. We have previously shown that PKCdelta gene was selectively expressed in spermatid of +/+ testes. Here we show that PKCdelta gene is also present in spermatid of Wsh/Wsh mice testes and PKCtheta gene was present in interstitial cells of +/+, Wsh/Wsh, and W/Wv mice testes. These studies provide the evidence of selective cell distributions of the PKC isoenzymes and suggest that PKC has the functional significance in testes.

Heterocyst formation in Anabaena

Heterocystous cyanobacteria grow as multicellular organisms with a distinct one-dimensional developmental pattern of single nitrogen-fixing heterocysts separated by approximately ten vegetative cells. Several genes have been identified that are required for heterocyst development and pattern formation. A key regulator, HetR, has been recently shown to be aserine-type protease.

Heterocyst pattern formation controlled by a diffusible peptide

Many filamentous cyanobacteria grow as multicellular organisms that show a developmental pattern of single nitrogen-fixing heterocysts separated by approximately 10 vegetative cells. Overexpression of a 54-base-pair gene, patS, blocked heterocyst differentiation in Anabaena sp. strain PCC 7120. A patS null mutant showed an increased frequency of heterocysts and an abnormal pattern. Expression of a patS-gfp reporter was localized in developing proheterocysts. The addition of a synthetic peptide corresponding to the last five amino acids of PatS inhibited heterocyst development. PatS appears to control heterocyst pattern formation through intercellular signaling mechanisms.

Expression of DAZ (deleted in azoospermia), DAZL1 (DAZ-like) and protamine-2 in testis and its application for diagnosis of spermatogenesis in non-obstructive azoospermia

Spermatogenesis is regulated by hormones, local regulatory factors in the testes and specific gene expression of spermatogenic cells in humans. In this study, we have detected the expression of the deleted in azoospermia (DAZ), the DAZ-like autosome (DAZL1), and the protamine-2 genes in spermatogenic cells. Spermatogenesis in 38 male infertility patients was evaluated by the semen analysis and histological examination. Patients were diagnosed as Sertoli cell-only syndrome (n = 20), maturation arrest (n = 6), hypospermatogenesis (n = 6), and obstructive azoospermic patients with normal spermatogenesis (n = 6). After microscopic observation of the wet preparation of the testis tissues, seminiferous tubule contents were used for reverse transcription-polymerase chain reaction (RT-PCR) analysis of DAZ, DAZL1 and protamine-2. In cases with Sertoli-cell only syndrome, we found spermatogenic cells in 30% of patients (6/20) by the wet preparation method. There was no difference between the histology and the wet preparation results in maturation arrest and obstructive azoospermia; however, in one case of hypospermatogenesis, spermatozoa were not detectable by the wet preparation method. Using in-situ hybridization with DAZ and protamine-2 ribonuclear probes, we confirmed spermatogenic cell-specific expression of DAZ (spermatogonia/early spermatocyte) and protamine-2 (spermatid/spermatozoon). DAZ and protamine-2 expression can therefore be considered spermatogenic cell markers and could be useful in molecular diagnosis of spermatogenesis. In 13 patients with spermatozoa under the wet preparation, the expression of DAZ, DAZL1 and protamine-2 was detected in all the preparations. In one wet preparation showing only spermatogonia/spermatocyte, only DAZ and DAZL1 RNA were detected. In 14 wet preparations showing no spermatogenic cells, DAZ, DAZL1 and protamine-2 were not detected except in one preparation where DAZL1 expression was detected. In 10 wet preparations representing spermatogonia/spermatocyte to spermatids, but showing no spermaozoa, DAZ and DAZL1 were detected in eight and nine preparations respectively, and protamine-2 was detected in six preparations. These results of gene expression were similar to the wet preparation results. RT-PCR for DAZ, DAZL1 and protamine-2 was informative for the existence of germ cells, germ cell physiology and differentiation. From these results, we suggest that the analysis of DAZ, DAZL1 and protamine-2 expression by RT-PCR and wet preparation might offer a better method for finding the spermatogenic cells compared to the histological method.

Determination of encephalomyocarditis viral diabetogenicity by a putative binding site of the viral capsid protein

The molecular mechanism by which some, but not all, variants of encephalomyocarditis (EMC) virus selectively infect pancreatic beta-cells in mice and induce IDDM has been an enigma for more than a decade. We report here that the binding site of the EMC viral capsid protein VP1 determines viral diabetogenicity. Recombinant chimeric EMC viruses containing threonine, serine, proline, aspartic acid, or valine at position 152 of the major capsid protein VP1 bind poorly to beta-cells. In contrast, recombinant chimeric EMC viruses containing alanine or glycine at position 152 of the VP1 bind efficiently to and infect beta-cells, resulting in the development of diabetes. Three-dimensional molecular modeling reveals that the van der Waals interactions are greater and the residues surrounding position 152 of the VP1 are more closely packed in recombinant chimeric viruses containing threonine, serine, proline, aspartic acid, or valine at position 152 than in recombinant chimeric viruses containing alanine or glycine at the same position. Our studies reveal that the surface areas surrounding alanine or glycine at position 152 of the VP1 are more accessible, thus increasing the availability of the binding sites for attachment to beta-cell receptors and resulting in viral infection and the development of diabetes.

The supplementation of culture medium with protease improves the hatching rate of mouse embryos

Mammalian embryos are known to exhibit delayed development and have lower hatching rates in vitro than in vivo because of inadequate culture condition. These discrepancies may be due to a deficiency of the paracrine factors and proteolytic enzymes which exist in the oviduct and uterus. In order to evaluate the effects of proteases on embryonic development and hatching, 2-cell mouse embryos were cultured for 72 h with or without proteases. The addition of 1.0 microg/ml pronase (PE) and/or 0.1 microg/ml proteinase K (PK) did not affect embryonic development up to the blastocyst stage (94.1% versus 88.2%; 92.2% versus 90.2%, respectively) but significantly increased the hatching rate (60.4% versus 39.2%, 71.8% versus 35.3%, respectively). However, the addition of alpha-chymotrypsin (Chymo) was detrimental to embryonic development and hatching. Changes in the structure of the zona pellucida (ZP) structure of embryos which had been cultured in human tubal fluid (HTF) medium with PE and PK were assessed by fluorescein isothiocyanate-conjugated (FITC)-casein. Embryos cultured in HTF-PE and PK were not stained with FITC-casein. When these embryos were cultured within oviducts, their perivitelline space (PVS) became strongly stained with FITC-casein which was easily removed by phosphate-buffered saline washing. This suggests that PE and PK altered the structure of the ZP. We suggest that the addition of PE and PK to culture media may accelerate the hatching of embryo, by structurally altering the ZP and PVS. This may provide a valuable and effective assisted hatching technique for human in-vitro fertilization-embryo transfer.

[Histological characterization and classification of surgically excised choroid neovascular membranes]

PURPOSE

This study was undertaken in order to histologically characterize surgically-excised choroidal neovascular membranes and to correlate theses histologic findings with the fundus and fluorescein angiographic appearance.

MATERIAL AND METHODS

Surgically-excised subfoveal choroidal neovascular membranes submitted in the time period from November 1994 to July 1996 were included in this study. The membranes were processed and evaluated by light and transmission electron microscopy. Some membranes were oriented by the surgeon and marked on their inner surface with India ink and the configurations of these membranes were recorded and correlated with the fundus and fluorescein angiographic features.

RESULTS

Sixty-two choroidal neovascular membranes were available for this study. In 74% age-related macular degeneration was the underlying disease. Retinal pigment epithelium and endothelial lined vascular channels were present in over 87.5% of cases. Basal laminar (linear) deposit was only present in membranes excised from patients with age-related macular degeneration. In six cases with Gass Type II choroidal neovascular membranes the histologic-clinical-fluorescein angiographic correlation showed well-defined (classic) neovascular membranes according to the criteria of the Macular Photocoagulation Study. Two membranes were not surrounded by retinal pigment epithelium and were classified as Type IIa membranes. Four membranes were surrounded by retinal pigment epithelium and classified as Type IIb membranes.

CONCLUSIONS

Choroidal neovascular membranes represent a stereotypic, non-specific wound repair response to a specific stimulus. Retinal pigment epithelium may proliferate around and attempt to wall off choroidal neovascular membranes. We propose a new classification of surgically-excised choroidal neovascular membranes as Types I, IIa, and IIb.

Analysis of the conformational change of recombinant human papilloma virus type 18 E7 protein induced by metal binding

Human papillomavirus (HPV) type 18 E7 gene was isolated by polymerase chain reaction (PCR) amplification from tissues of Korean cervical cancer patients and cloned into a plasmid vector, pET-3a, for the expression of recombinant E7 protein (rE7) in Escherichia coli. The rE7 protein was purified to the homogeneity and its purity was confirmed by HPLC. The purified protein was analyzed for the metal-binding properties by UV spectroscopy and it was shown that two Cd2+ or Zn2+ ions bind to one E7 protein by the metal-sulfur ligand formation via two Cys-X-X-Cys motifs in E7 protein. When the change of intrinsic fluorescence of tryptophan residue was analyzed for rE7-Zn complex, the blue shift of emission wavelength and the decrease in maximum intensity of emission were observed compared with rE7. These results suggest that Zn(2+)-bound rE7 has undergone conformational change, in which a tryptophan residue located in the second Cys-X-X-Cys motif was moved into solvent-inaccessible or hydrophobic environment. The rE7-Zn complex was found to be resistant to chymotrypic digestion by comparing the digestion patterns of rE7. Therefore, we showed the folding status of HPV 18 E7 could be changed by metal binding resulting in a different conformation in which a tryptophan residue was driven into more hydrophobic environment and the resistancy to chymotryptic digestion was conferred.

Effect of a novel saponin adjuvant derived from Quillaja saponaria on the immune response to recombinant hepatitis B surface antigen

Adjuvant activity of saponins extracted from the South American tree Quillaja saponaria has been demonstrated with many antigens. Recently, four saponin fractions (designated as QS-7, QS-17, QS-18, and QS-21) with adjuvant activity were purified by reverse phase chromatography. In particular, efficacy of the less toxic QS-21 fraction has been demonstrated with several recombinant viral antigens including HIV gp120. Here, we report a novel saponin fraction (designated as QS-L1) derived from Quillaja saponaria. Unlike previously identified saponins, QS-L1 had a different chemical structure and showed adjuvant activity only when administered in the presence of alum-precipitated antigen. Interestingly, the QS-L1 greatly increased not only a humoral immune response but also cellular immune response to recombinant hepatitis B virus surface antigen (HBsAg). Furthermore, QS-L1 showed lower toxicity in vivo and in vitro than the previously identified saponin fraction, QS-21. Finally, we examined the chemical structure of the QS-L1 using mass spectroscopic analysis, carbohydrate composition analysis and NMR spectroscopic analysis. Thus, our results indicated that this novel QS-L1 saponin fraction had several desirable properties required for an effective adjuvant.

Structure of Bcl-xL-Bak peptide complex: recognition between regulators of apoptosis

Heterodimerization between members of the Bcl-2 family of proteins is a key event in the regulation of programmed cell death. The molecular basis for heterodimer formation was investigated by determination of the solution structure of a complex between the survival protein Bcl-xL and the death-promoting region of the Bcl-2-related protein Bak. The structure and binding affinities of mutant Bak peptides indicate that the Bak peptide adopts an amphipathic alpha helix that interacts with Bcl-xL through hydrophobic and electrostatic interactions. Mutations in full-length Bak that disrupt either type of interaction inhibit the ability of Bak to heterodimerize with Bcl-xL.

Induction of acrosome reaction in human spermatozoa accelerates the time of pronucleus formation of hamster oocytes after intracytoplasmic sperm injection

OBJECTIVE

To assess the relationship between the incidence of acrosome reaction (AR) and the timing of pronucleus (PN) formation after intracytoplasmic sperm injection (ICSI).

DESIGN

Prospective study.

SETTING

Infertility Research Center, Jeil Women's Hospital.

MAIN OUTCOME MEASURE(S)

Human semen obtained from fertile donors was prepared by one of the following methods: washing only (washed control); Percoll gradient; pentoxifylline; human follicular fluid (FF); pentoxifylline + FF; or platelet-activating factor (PAF) treatment. The AR of each group was assessed by fluorescein isothiocyanate-conjugated Pisum sativum agglutinin or Arachis hypogea agglutinin. Spermatozoa of washed control, pentoxifylline + FF, and PAF treated groups, with significantly higher AR rate than others, were injected into mature hamster oocytes. Spermatozoon-injected oocytes were cultured for 6, 9, 12, or 15 hours. Then they were stained with Toluidine blue for PN formation examination under a light microscope.

RESULT(S)

Acrosome reaction rates of washed control, Percoll gradient, pentoxifylline, FF, pentoxifylline + FF, and PAF treated groups were 10.5% +/- 2.6%, 10.3% +/- 1.7%, 16.4% +/- 1.8%, 24.8% +/- 5.6%, 28.4% +/- 3.8%, and 33.3% +/- 5.2%, respectively. Pronuclear formation rate in washed control, pentoxifylline + FF, and PAF treated groups were 5.6% (3/54), 19.0% (11/58), and 18.9% (10/53) at 6 hours; 32.7% (18/55), 51.8% (29/56), and 57.4% (31/54) at 9 hours; 36.1% (22/61), 53.6% (30/56), and 50.0% (27/54) at 12 hours; and 47.2% (25/53), 64.8% (35/54), 53.6% (30/56) at 15 hours after ICSI. Pronuclear formation rate was significantly higher in pentoxifylline + FF, and PAF treated groups than that in the washed control group at 6 and 9 hours after ICSI.

CONCLUSION(S)

Pronuclear formation of oocytes takes place faster on those that were injected with acrosome-reacted spermatozoon than those injected with acrosome-intact spermatozoon. It could be concluded that induction of the AR of spermatozoa accelerates the time of PN formation and early development of the embryo in ICSI.

X-ray and NMR structure of human Bcl-xL, an inhibitor of programmed cell death

THE Bcl-2 family of proteins regulate programmed cell death by an unknown mechanism. Here we describe the crystal and solution structures of a Bcl-2 family member, Bcl-xL (ref. 2). The structures consist of two central, primarily hydrophobic alpha-helices, which are surrounded by amphipathic helices. A 60-residue loop connecting helices alpha1 and alpha2 was found to be flexible and non-essential for anti-apoptotic activity. The three functionally important Bcl-2 homology regions (BH1, BH2 and BH3) are in close spatial proximity and form an elongated hydrophobic cleft that may represent the binding site for other Bcl-2 family members. The arrangement of the alpha-helices in Bcl-xL is reminiscent of the membrane translocation domain of bacterial toxins, in particular diphtheria toxin and the colicins. The structural similarity may provide a clue to the mechanism of action of the Bcl-2 family of proteins.

Solution structure of the DNA-binding domain of a human papillomavirus E2 protein: evidence for flexible DNA-binding regions

The three-dimensional structure of the DNA-binding domain of the E2 protein from human papillomavirus-31 was determined by using multidimensional heteronuclear nuclear magnetic resonance (NMR) spectroscopy. A total of 1429 NMR-derived distance and dihedral angle restraints were obtained for each of the 83-residue subunits of this symmetric dimer. The average root mean square deviations of 20 structures calculated using a distance geometry-simulated annealing protocol are 0.59 and 0.90 angstroms for the backbone and all heavy atoms, respectively, for residues 2-83. The structure of the human virus protein free in solution consists of an eight-stranded beta-barrel and two pairs of alpha-helices. Although the overall fold of the protein is similar to the crystal structure of the bovine papillomavirus-1 E2 protein when complexed to DNA, several small but interesting differences were observed between these two structures at the subunit interface. In addition, a beta-hairpin that contacts DNA in the crystal structure of the protein-DNA complex is disordered in the NMR structures, and steady-state 1H-15N heteronuclear NOE measurements indicate that this region is highly mobile in the absence of DNA. The recognition helix also appears to be flexible, as evidenced by fast amide exchange rates. This phenomenon has also been observed for a number of other DNA-binding proteins and may constitute a common theme in protein/DNA recognition.

Antibodies prevalence against HPV-6b and -16 recombinant fusion proteins in Korean patients with cervical neoplasia

OBJECTIVES

This study was to investigate the adjunctive diagnostic utility of HPV fusion proteins from the sera in the patients with cervical neoplasia. Immunologic researches on host factors in HPV infection could contribute to better understanding of patho-physiologic mechanisms of cervical carcinogenesis, and provide valuable information for HPV vaccine development.

METHODS

Prevalence of antibodies against human papillomavirus (HPV) in sera of the patients with carcinoma (n = 81), precancers (n = 25) of uterine cervix and normal controls (n = 40) in Korean women were investigated by Western blot immunoassay using partially purified TrpE fusion recombinant proteins for HPV-6b and HPV-16.

RESULTS

In 81 patients with cervical cancer, 15 (19%) and 54 (67%) patients were positive for antibodies to at least one of the tested recombinant proteins related to HPV-6b or HPV-16, respectively. And in 25 patients with HPV-related squamous intraepithelial lesion (SIL) of cervix, 10 were positive for at least one of the tested antibodies for HPV-6b gene products (40%) and 11 were positive for HPV-16 related antibodies (44%). The prevalence rates of antibodies for HPV-6b in the sera of SIL patients were significantly higher than those from the sera of cervical cancer patients (p < 0.05). There was an inverse correlation between increasing the positivity against HPV-16 E6 protein and progression of cervical lesions, but there was no significant correlation between the positivities of the other antibodies to HPV-16 and the severity of disease.

CONCLUSION

These results suggest that the recombinant proteins related to HPV-6b and HPV-16 could be useful in evaluation of the patients with HPV-related cervical lesions and these might play an adjunctive role in diagnosis and management of cervical neoplasia.

Solution structure of the Shc SH2 domain complexed with a tyrosine-phosphorylated peptide from the T-cell receptor

She is a widely expressed adapter protein that plays an important role in signaling via a variety of cell surface receptors and has been implicated in coupling the stimulation of growth factor, cytokine, and antigen receptors to the Ras signaling pathway. She interacts with several tyrosine-phosphorylated receptors through its C-terminal SH2 domain, and one of the mechanisms of T-cell receptor-mediated Ras activation involves the interaction of the Shc SH2 domain with the tyrosine-phosphorylated zeta chain of the T-cell receptor. Here we describe a high-resolution NMR structure of the Shc SH2 domain complexed to a phosphopeptide (GHDGLpYQGLSTATK) corresponding to a portion of the zeta chain of the T-cell receptor. Although the overall architecture of the protein is similar to other SH2 domains, distinct structural differences were observed in the smaller beta-sheet, BG loop, (pY + 3) phosphopeptide-binding site, and relative position of the bound phosphopeptide.

Structural characterization of the interaction between a pleckstrin homology domain and phosphatidylinositol 4,5-bisphosphate

The pleckstrin homology (PH) domain is a protein module of approximately 100 amino acids that is found in several proteins involved in signal transduction [for a recent review, see Gibson et al. (1994) Trends Biochem. Sci. 19, 349-353]. Although the specific function of the PH domain has not yet been elucidated, many of the proteins which contain this domain associate with phospholipid membranes, and PH domains have been shown to bind to phosphatidylinositol 4,5-bisphosphate (PIP2) [Harlan et al. (1994) Nature 371, 168-170] and the beta gamma subunits of G-proteins [Touhara et al. (1994) J. Biol. Chem. 269, 10217-10220]. We have postulated that pleckstrin homology domains may be important for the translocation of proteins to the membrane by an interaction with the negatively charged head group of phospholipids. Here we show the importance of three conserved lysine residues for binding to PIP2 by site-directed mutagenesis. These results should aid future site-directed mutagenesis studies in probing the function of PIP2-PH domain interactions in the various proteins containing this module. In addition, we examine the specificity of this binding and illustrate the importance of charge--charge interactions in PIP2-PH domain complex formation from binding experiments involving PIP2 analogs.

Partial annular plication for atrioventricular valve regurgitation

Various annuloplasty techniques are used to correct tricuspid or mitral valve regurgitation. We performed a partial annular plication procedure, a modification of the annuloplasty introduced by Davila, in 23 consecutive patients with moderate to severe tricuspid regurgitation or moderate mitral regurgitation. A slender plastic tube was used to tighten snugly the suture during intraoperative saline flushing test for assessment of the valve competency. This technique enabled us to add one stitch or two for more plication before the suture was tied if necessary. During a mean follow-up period of 13.8 months postoperatively, 10 patients (43.5%) had no valve regurgitation, 12 patients (52.2%) had grade 1+ regurgitation, and 1 patient (4.3%) grade 2+ on color Doppler echocardiography. The regurgitation grade remained unchanged or improved after the initial postoperative study. Our surgical experience indicates that the adjustable procedure of partial annular plication is a simple, exact, and durable procedure in patients of all ages with moderate to severe functional atrioventricular regurgitation.

Intestinal transit and opaque enema study in chagasic mice

The report concerns as experimental study utilizing thirty-three mice inoculated subcutaneously with 1000 blood forms of Trypanosoma cruzi. Intestinal transit and morphology of colon were studies by means of X-rays. In subacute stage intestinal transit was normal. In chronic stages the mice displayed a delay in evacuation time. In one out of 12 animals the opaque enema documented the existence of megacolon.

Pleckstrin homology domains bind to phosphatidylinositol-4,5-bisphosphate

The pleckstrin homology (PH) domain is a new protein module of around 100 amino acids found in several proteins involved in signal transduction. Although its specific function has yet to be elucidated, the carboxy-terminal regions of many PH domains bind to the beta gamma subunits of G proteins. On the basis of structural similarities between PH domains and lipid-binding proteins, we have proposed that PH domains may be binding to lipophilic molecules. Indeed, many of the proteins that contain this domain associate with phospholipid membranes, and disruption of this domain can interfere with membrane association. Here we report that PH domains bind to phosphatidylinositol-4,5-bisphosphate and show that the lipid-binding site is located at the lip of the beta-barrel. This suggests that PH domains may be important for membrane localization of proteins through interactions with phosphatidylinositol-4,5-bisphosphate.

Solution structure of a pleckstrin-homology domain

Pleckstrin, the major protein kinase C substrate of platelets, contains domains of about 100 amino acids at the amino and carboxy termini that have been found in a number of proteins, including serine/threonine kinases, GTPase-activating proteins, phospholipases and cytoskeletal proteins. These conserved sequences, termed pleckstrin-homology (PH) domains, are thought to be involved in signal transduction. But the details of the function and binding partners of the PH domains have not been characterized. Here we report the solution structure of the N-terminal pleckstrin-homology domain of pleckstrin determined using heteronuclear three-dimensional nuclear magnetic resonance spectroscopy. The structure consists of an up-and-down beta-barrel of seven antiparallel beta-strands and a C-terminal amphiphilic alpha-helix that caps one end of the barrel. The overall topology of the domain is similar to that of the retinol-binding protein family of structures.

The pattern of spontaneous germ-line mutation: relative rates of mutation at or near CpG dinucleotides in the factor IX gene

Mutations at CpG dinucleotides were delineated in the factor IX gene of 38 hemophilia B patients. When transitions at CpG were considered with those previously reported by us and those compiled in the factor IX mutation database, the following patterns emerged. Many CpG sites were mutated with high frequency, while two CpG sites were infrequently mutated (R29-->Q and R116-->TGA). Of the 6 possible nonsense mutations and the 14 missense mutations that would produce a nonconservative change at conserved amino acids, all have been observed to cause hemophilia B except A-10-->T and R338-->Q. By contrast, none of the 6 missense changes at nonconserved amino acids have been observed to cause hemophilia B. At those CpG sites that are frequently mutated, the rate of transitions is estimated to be 20-fold higher than transitions at non-CpG sites. Point mutations in close proximity to CpG dinucleotides did not seem elevated.

Germline mutations in the factor IX gene: a comparison of the pattern in Caucasians and non-Caucasians

DNA samples of patients from around the world have been sequenced to precisely define the mutations in the factor IX gene resulting in hemophilia B. This study compares the patterns of independent mutation between 127 Caucasian and 44 non-Caucasian patients with hemophilia B. Caucasians and non-Caucasians are found to have similar patterns of transitions and transversions (both at CpG and at non-CpG sites) as well as insertions, deletions, microdeletions, and complex changes (chi 2 = 2.71, p = 0.922). An analysis of subgroups of transitions and transversions shows similar patterns among Caucasians and non-Caucasians (chi 2 = 2.98, p = 0.83). If the subset of non-Caucasian samples (24) in which the mutation is known to have occurred outside of the United States, Canada, and Europe (UCE) is compared to the Caucasian subset, the above conclusions are unchanged. The invariant nature of this pattern of mutation is most simply compatible with a predominance of endogenous processes or common mutagen exposure rather than mutagen exposure specifically associated with non-Caucasian status or non-Western lifestyle.

Dideoxy fingerprinting (ddE): a rapid and efficient screen for the presence of mutations

We describe dideoxy fingerprinting (ddF), a hybrid between dideoxy sequencing and SSCP that can detect the presence of single base and other sequence changes in PCR-amplified segments. As implemented herein, ddF involves a Sanger sequencing reaction with one dideoxynucleotide followed by nondenaturing gel electrophoresis. When ddF was used to examine segments of the human factor IX gene, 84 of 84 different mutations were detected with a very low rate of false positive signals. The approximate locations of the sequence changes could be determined from the ddF pattern and samples with different sequence changes had different fingerprints. In addition, large segments could be amplified and rapidly screened by ddF in multiple smaller subsegments. The patterns observed with ddF are instructive in that they suggest an inherent limitation in the detection of certain mutations by SSCP.