Structural foundation for the role of enterococcal PrgB in conjugation, biofilm formation, and virulence

Type 4 Secretion Systems are a main driver for the spread of antibiotic resistance genes and virulence factors in bacteria. In Gram-positives, these secretion systems often rely on surface adhesins to enhance cellular aggregation and mating-pair formation. One of the best studied adhesins is PrgB from the conjugative plasmid pCF10 of Enterococcus faecalis, which has been shown to play major roles in conjugation, biofilm formation, and importantly also in bacterial virulence. Since prgB orthologs exist on a large number of conjugative plasmids in various different species, this makes PrgB a model protein for this widespread virulence factor. After characterizing the polymer adhesin domain of PrgB previously, we here report the structure for almost the entire remainder of PrgB, which reveals that PrgB contains four immunoglobulin (Ig)-like domains. Based on this new insight, we re-evaluate previously studied variants and present new in vivo data where specific domains or conserved residues have been removed. For the first time, we can show a decoupling of cellular aggregation from biofilm formation and conjugation in prgB mutant phenotypes. Based on the presented data, we propose a new functional model to explain how PrgB mediates its different functions. We hypothesize that the Ig-like domains act as a rigid stalk that presents the polymer adhesin domain at the right distance from the cell wall.

Bacterial persisters are a stochastically formed subpopulation of low-energy cells

Persisters represent a small subpopulation of non- or slow-growing bacterial cells that are tolerant to killing by antibiotics. Despite their prominent role in the recalcitrance of chronic infections to antibiotic therapy, the mechanism of their formation has remained elusive. We show that sorted cells of Escherichia coli with low levels of energy-generating enzymes are better able to survive antibiotic killing. Using microfluidics time-lapse microscopy and a fluorescent reporter for in vivo ATP measurements, we find that a subpopulation of cells with a low level of ATP survives killing by ampicillin. We propose that these low ATP cells are formed stochastically as a result of fluctuations in the abundance of energy-generating components. These findings point to a general "low energy" mechanism of persister formation.

Enterococcal PrgA Extends Far Outside the Cell and Provides Surface Exclusion to Protect against Unwanted Conjugation

Horizontal gene transfer between Gram-positive bacteria leads to a rapid spread of virulence factors and antibiotic resistance. This transfer is often facilitated via type 4 secretion systems (T4SS), which frequently are encoded on conjugative plasmids. However, donor cells that already contain a particular conjugative plasmid resist acquisition of a second copy of said plasmid. They utilize different mechanisms, including surface exclusion for this purpose. Enterococcus faecalis PrgA, encoded by the conjugative plasmid pCF10, is a surface protein that has been implicated to play a role in both virulence and surface exclusion, but the mechanism by which this is achieved has not been fully explained. Here, we report the structure of full-length PrgA, which shows that PrgA protrudes far out from the cell wall (approximately 40 nm), where it presents a protease domain. In vivo experiments show that PrgA provides a physical barrier to cellular adhesion, thereby reducing cellular aggregation. This function of PrgA contributes to surface exclusion, reducing the uptake of its cognate plasmid by approximately one order of magnitude. Using variants of PrgA with mutations in the catalytic site we show that the surface exclusion effect is dependent on the activity of the protease domain of PrgA. In silico analysis suggests that PrgA can interact with another enterococcal adhesin, PrgB, and that these two proteins have co-evolved. PrgB is a strong virulence factor, and PrgA is involved in post-translational processing of PrgB. Finally, competition mating experiments show that PrgA provides a significant fitness advantage to plasmid-carrying cells.

Functional characterization of Trip10 in cancer cell growth and survival

Background

The Cdc42-interacting protein-4, Trip10 (also known as CIP4), is a multi-domain adaptor protein involved in diverse cellular processes, which functions in a tissue-specific and cell lineage-specific manner. We previously found that Trip10 is highly expressed in estrogen receptor-expressing (ER⁺) breast cancer cells. Estrogen receptor depletion reduced Trip10 expression by progressively increasing DNA methylation. We hypothesized that Trip10 functions as a tumor suppressor and may be involved in the malignancy of ER-negative (ER^-) breast cancer. To test this hypothesis and evaluate whether Trip10 is epigenetically regulated by DNA methylation in other cancers, we evaluated DNA methylation of Trip10 in liver cancer, brain tumor, ovarian cancer, and breast cancer.

Methods

We applied methylation-specific polymerase chain reaction and bisulfite sequencing to determine the DNA methylation of Trip10 in various cancer cell lines and tumor specimens. We also overexpressed Trip10 to observe its effect on colony formation and in vivo tumorigenesis.

Results

We found that Trip10 is hypermethylated in brain tumor and breast cancer, but hypomethylated in liver cancer. Overexpressed Trip10 was associated with endogenous Cdc42 and huntingtin in IMR-32 brain tumor cells and CP70 ovarian cancer cells. However, overexpression of Trip10 promoted colony formation in IMR-32 cells and tumorigenesis in mice inoculated with IMR-32 cells, whereas overexpressed Trip10 substantially suppressed colony formation in CP70 cells and tumorigenesis in mice inoculated with CP70 cells.

Conclusions

Trip10 regulates cancer cell growth and death in a cancer type-specific manner. Differential DNA methylation of Trip10 can either promote cell survival or cell death in a cell type-dependent manner.

DNA methylation of the Trip10 promoter accelerates mesenchymal stem cell lineage determination

Epigenetic regulation of gene expression by DNA methylation and histone modification controls cell fate during development and homeostasis in adulthood. Aberrant epigenetic modifications may lead to abnormal development, even diseases. We have found that Trip10 (thyroid hormone receptor interactor 10), an adaptor protein involved in diverse functions, is epigenetically regulated during lineage-specific induction of human bone marrow-derived mesenchymal stem cells (MSCs). To determine whether DNA methylation-induced gene silencing is sufficient to restrict cell fate changes, we applied an invitro method to specifically methylate the promoter of Trip10. Our hypothesis was that the methylation status of the Trip10 promoter in MSCs alters the differentiation preference of MSCs. Transfection of in vitro-methylated Trip10 promoter DNA into MSCs resulted in progressive accumulation of cytosine methylation at the endogenous Trip10 promoter, reduced Trip10 expression, and accelerated MSC-to-neuron and MSC-to-osteocyte differentiation. A two-component EGFP reporter gene system was established to confirm the level of transcriptional silencing and visualize the targeted DNA methylation. EGFP expression induced in the reporter system by targeted Trip10 methylation was reversed by adding 5-aza-2'-deoxycytidine, a DNA methyltransferase inhibitor, confirming that the suppressed Trip10 expression and disrupted MSC differentiation resulted from the in vitro-introduced methylations in the Trip10 promoter. With this targeted DNA methylation and reporter system, we are able to monitor the progression of locus-specific DNA methylation in vivo and correlate such changes with potential functional changes. Using this approach, we have established a new role for Trip10, showing that the level of Trip10 expression is associated with the maintenance and differentiation of MSCs.

Clinical implications of coexpression of growth arrest-specific gene 6 and receptor tyrosine kinases Axl and Sky in human uterine leiomyoma

The expression of Gas6, the protein product of the growth arrest-specific gene 6 (gas6), a member of the vitamin K-dependent protein family, and the receptor tyrosine kinases Axl and Sky and their mRNAs in uterine leiomyoma and normal uterine myometrium tissues were investigated by competitive RT-PCR-Southern blot analysis using recombinant RNA and immuno histochemical analysis respectively. There was no significant difference between the histoscores and levels of Sky mRNA in uterine leiomyoma and normal uterine myometrium, although the levels of Gas6 and Axl mRNAs in uterine leiomyoma were significantly higher than in normal uterine myometrium in each case. It is suggested that Gas6 and Axl signal transduction is aberrantly stimulated in uterine leiomyoma, possibly related to its growth.

[Long distance-PCR for detection of factor VIII gene inversion in patients with severe hemophilia A]

The aim of current study was to detect intron 22 inversion of factor VIII gene in severe hemophilia A (HA) patients and screen the carriers of the gene inversion. Fifty-five cases of severe HA were involved and factor VIII gene inversion was detected and identified by long distance-PCR (LD-PCR) and 0.6% agarose gel electrophoresis. The 11 kb and 12 kb bands indicate the factor VIII gene inversion and non-inversion, respectively. Occurring of both 11 kb and 12 kb bands indicates a carrier of the inversion. The results showed that factor VIII gene inversion existed in 22 out of 55 cases, which accounted for about 40% of total detected patients. Five carriers of factor VIII gene inversion were diagnosed from the members in 15 families. In conclusion, LD-PCR assay is a simple, rapid and accurate method for detection of factor VIII gene inversion, and this approach is helpful in screening, carrier testing, and prenatal diagnosis of severe hemophilia A.

Coexpression of growth arrest-specific gene 6 and receptor tyrosine kinases Axl and Sky in human uterine endometrial cancers

BACKGROUND

Gas6, the protein product of the growth arrest-specific gene 6 (gas6), a member of the vitamin K-dependent protein family, was identified as a ligand for the Axl/Sky family of receptor tyrosine kinases. Gas6 acts as a growth-potentiating factor for thrombin-induced proliferation of vascular smooth muscle cells. The aim of the present study was to test for the presence of Gas6 and its receptors Axl and Sky, related to specific growth in uterine endometrial cancers, and to evaluate their plausible growth potential and mechanism.

MATERIALS AND METHODS

Sixty patients underwent curative resection for uterine endometrial cancers. In uterine endometrial cancers, the mRNA levels and histoscores of Gas6, Axl and Sky were determined by competitive RT-PCR using recombinant RNA and immunohistochemical studies, respectively. The rate of proliferation by immunochemistry for Ki67 and the rate of apoptosis by TUNEL were determined.

RESULTS

The mRNA levels and the histoscores of Gas6 and Axl in well-differentiated endometrial cancers (G1 EC) were significantly higher than in normal uterine endometrium (NE) and in moderately and poorly differentiated endometrial cancers (G2 + G3 EC). The rate of apoptosis in G1 EC was significantly lower than that in NE and in G2 + G3 EC.

CONCLUSIONS

Gas6 and Axl signal transduction is aberrantly stimulated in well-differentiated endometrial cancers, plausibly related to tumor progression due to protection from apoptosis in cancers cells.

Dopamine D2 receptors internalize in their low-affinity state

The present study was done in order to determine whether dopamine internalizes D2 receptors in CHO cells and whether the high-affinity or the low-affinity state of the dopamine D2 receptor is associated with dopamine-induced internalization of dopamine D2 receptors. Using [3H]sulpiride to label D2Long receptors in CHO cells, it was found that dopamine lowered the binding of [3H]sulpiride by 20%. Although the high-affinity states of D2 were converted to low-affinity states by guanine nucleotide, the latter had no effect in blocking the dopamine-induced reduction in [3H]sulpiride binding, indicating that the dopamine-induced internalization of D2 receptors occurred with D2 in the low-affinity state.

Coexpression of growth arrest-specific gene 6 and receptor tyrosine kinases, Axl and Sky, in human uterine endometrium and ovarian endometriosis

We demonstrated the expression of Gas6, the protein product of the growth arrest-specific gene 6 (gas6) and a member of the vitamin K-dependent protein family, and its receptor tyrosine kinases, Axl and Sky, in human uterine and ovarian endometriotic endometria using RT-PCR-Southern blot analysis and immunohistochemistry. Gas6, Axl and Sky mRNA were detected in all samples analysed. There was no significant difference between the levels of Sky mRNA in normal uterine and endometriotic endometria; however, the levels of Gas6 and Axl mRNA in endometriotic endometria were significantly higher than in normal endometria. These mRNA levels showed no significant alteration during the menstrual cycle. In the immunohistochemical study, Gas6, Axl and Sky were found in endometrial glandular cells and stromal cells in all samples analysed. This study demonstrates the coexpression of receptor tyrosine kinases and their ligand, Gas6, in normal uterine and ovarian endometriotic endometria, and the overexpression of Axl and Gas6 in endometriotic endometria. It is suggested that Gas6 and Axl signal transduction is aberrantly stimulated in endometriotic endometria, and is plausibly related to its growth potential.

YUA001, a novel aldose reductase inhibitor isolated from alkalophilic Corynebacterium sp. YUA25. II. Chemical modification and biological activity

A series of novel N-substituted tyramine (2-p-hydroxyphenylethylamine) derivatives (1 to approximately 11) were synthesized and evaluated for their inhibitory activity against pig kidney aldose reductase (EC 1, 1, 1, 21). Of these compounds, N-2-p-hydroxyphenylethyl maleamic acid (10) exhibits the strongest aldose reductase inhibitory activity, which is 22 times more potent than that of YUA001.

Synthesis of 2',3'-dideoxyisoguanosine from guanosine

2,3'-Dideoxyisoguanosine was synthesized from guanosine via intermediate 6-[(4-methylphenyl)thio]-2-oxo-9-(2',3',5'-tri-O-acetyl-beta-D-ribofuran osyl)-2,3-dihydropurine (4). The 2-oxo, 6-amino and 5'-hydroxy triprotected isoguanosine derivative was utilized to reduce high polarity and promote poor solubility of intermediates. The protecting groups for oxo and 6-amino were easily removed in reduction of olefin in ribose without additional reaction steps. 2',3'-Vicinal diol in ribose sugar moiety was transformed to olefin with Bu3SnH by radical reaction via bisxanthate. Removing 5'-O-TBDMS protecting group gave final product, 2',3'-dideoxyisoguanosine (12) in a 10% overall yield.

Evidence for the synthesis of corticosteroid-binding globulin in human placenta

We demonstrated the expression of corticosteroid-binding globulin (CBG) in human placenta using reverse transcription-polymerase chain reaction-Southern blot analysis and immunohistochemical and immunoblotting studies. In the RT-PCR-Southern blot analysis, only one predicted PCR product was detected without nonspecific products in all samples of human placenta and 3A (tPA-30-1) human placental cells. In Western blot analysis, polyclonal anti-CBG antibodies recognized a protein of approximately 55 kD in the protein extracts prepared from 3A (tPA-30-1) cells. Additionally, CBG mRNA expression was demonstrated by in situ hybridization in the syncytiotrophoblasts. Immunohistochemical studies performed on the placenta demonstrated the presence of specific immunoreactivity in the syncytiotrophoblast layer surrounding the chorionic villi. These findings suggest that CBG is synthesized in human placenta during pregnancy in addition to its synthesis in the liver.

Levels of corticosteroid-binding globulin mRNA in human ovarian cancers

To understand the role of corticosteroid-binding globulin (CBG) in the intracellular steroidal actions in human ovarian cancers, the level of CBG mRNA expression was evaluated in normal ovarian tissues and in ovarian cancers using competitive reverse transcription-polymerase chain reaction-Southern blot analysis. The expression of CBG mRNA was detected in all normal ovaries and ovarian cancers analyzed. There were no significant differences in the mean CBG mRNA levels between normal ovaries and ovarian cancers. The expression in normal ovaries was significantly higher (p < 0.01) in the premenopause than in the postmenopause. A high expression of CBG mRNA was observed in 11 out of 29 cases (38%) of ovarian cancer in comparison with normal ovaries. There was no difference in the expression among the histological classifications or clinical stages of ovarian cancers. These data suggest that human normal ovaries and ovarian cancers might synthesize CBG intracellularly, ovarian cancers might conserve a progesterone-associated property via CBG, and the regulation of intracelluar CBG expression might be changed in some cancers.

Expression of sex hormone-binding globulin exon 7 splicing variant mRNA in secondary spreading lesions of gynecological cancers

This study was designed to determine the clinical implications of intracellular expression of sex hormone-binding globulin (SHBG) wild-type and exon 7 splicing variant mRNAs in secondary spreading lesions of gynecologic cancers using the reverse transcription-polymerase chain reaction-Southern blot and DNA sequencing analyses. Compared with primary cancers, a relative increase in SHBG variant mRNA to wild-type mRNA expression was observed (4/10 cases of uterine endometrial cancers, 5/10 cases of uterine cervical cancers, 6/10 cases of ovarian cancers) or the expression of SHBG wild-type and variant mRNAs could not be detected (5/10 cases of uterine endometrial cancers, 3/10 cases of uterine cervical cancers, 4/10 cases of ovarian cancers). On the other hand, alteration to a relative increase in SHBG wild-type mRNA expression in the metastatic lesions occurred in only 3 cases (1/10 cases of uterine endometrial cancers and 2/10 cases of uterine cervical cancers) analyzed. These results suggest that the transcription of SHBG mRNA and the regulation of its splicing might be altered with metastatic potential, and this status might be involved in a change in steroidal dependency of metastatic lesions.

Expression of oestrogen receptor alpha and beta mRNA in corpus luteum of human subjects

To investigate the role of oestrogen receptor beta (ERbeta) in the function of human ovarian corpus luteum, the levels of luteal ERalpha and ERbeta mRNA were determined using competitive reverse transcription-polymerase chain reaction-Southern blot analysis. The expression of ERalpha and ERbeta mRNA was detected in all luteal samples analysed. Luteal ERalpha and ERbeta mRNA levels were significantly lower (P<0.01 and P<0.05 respectively) at the late secretory phase than those at the early and mid-secretory phases of the endometrium. The ratio of ERalpha to ERbeta mRNA levels showed no change during the secretory phase of the endometrium. This study demonstrates that ERbeta is co-expressed with ERalpha in human corpus luteum and is likely to play a biological role in the regulation of steroidal action of the corpus luteum with ERalpha.

Identification of various exon-deleted progesterone receptor mRNAs in human endometrium and ovarian endometriosis

We demonstrated the expression of various exon-deleted progesterone receptor (PR) variant mRNAs in human uterine endometrium and ovarian endometriosis using the reverse transcription-polymerase chain reaction-DNA sequencing analyses. In addition to PR wild-type mRNA, various exon-deleted PR variant mRNAs were identified in all samples analyzed. The sequence of these variants showed a perfect junction between exons surrouding the deletion area. PR wild-type, exon 6-deleted, exon 4-deleted, exon 5, 6-deleted and exon 4, 5, 6-deleted PR variant mRNAs were observed in all samples analyzed. Exon 4, 6-deleted PR mRNA was observed only in ovarian endometriosis. This is the first study to demonstrate the coexpression of various PR exon-deleted variant mRNAs with the wild-type in uterine endometrium and ovarian endometriosis. All resulting variant proteins might indicate functional diversity and modify the progestational action of wild-type PR, and thus be involved in the pathophysiology of ovarian endometriosis.

Maladaptive neural compensatory mechanisms in Bell's palsy-induced blepharospasm

We described four patients with Bell's palsy and blepharospasm and evaluated potential mechanisms that may be responsible for an apparent association between the two disorders. Eyelid movements in spontaneous blinks were studied by the search coil technique in patients with this novel disorder. Kinematic analyses documented bilateral eyelid spasm subsequent to unilateral Bell's palsy. The temporal interval between the onset of palsy and onset of blepharospasm was highly variable (weeks to > 20 years). Changes in the relationship between spontaneous blink peak velocity and amplitude, the main sequence, shared features previously found in uncomplicated Bell's palsy and blepharospasm patients. Furthermore, as in patients with typical Bell's palsy and idiopathic blepharospasm, both normal blinks and spasms were conjugate in spite of interocular differences in blink amplitude/peak velocity. We suggest that there is a correlation between the eyelid palsy and subsequent blepharospasm, and have designated this potentially new disease entity as Bell's palsy-induced blepharospasm. We propose a two-stage model for Bell's palsy-induced blepharospasm in which blink adaptive systems may produce the maladaptive consequence of eyelid spasms.

The role of blink adaptation in the pathophysiology of benign essential blepharospasm

OBJECTIVE

To investigate eyelid movements in patients with benign essential blepharospasm (BEB), with an emphasis on the characterization of the kinematics of normal and spastic blinks, assessment of interocular differences, and further delineation of the role of adaptive blink mechanisms in eyelid movement disorders.

PATIENTS AND METHODS

The electromagnetic search coil technique was used to record the metrics of blinks bilaterally in 5 patients with untreated BEB. Eyelid kinematics and the main-sequence (peak velocity vs amplitude) relationships were analyzed.

RESULTS

Patients with BEB exhibited a decrease in blink amplitude and peak velocity. Moreover, the main-sequence slope was decreased bilaterally. Spasms were bilateral and relatively conjugate. There was no change in the coordination of normal blinking across the 2 eyelids.

CONCLUSIONS

These data demonstrate the operation of the adaptive regulation of blinking in an eyelid movement disorder. The findings suggest that the adaptive regulation of blink is a bilateral event. Blink-adaptive control systems can act on the blink reflex excitability and main-sequence relationships, changing these either together or independently. The hyperexcitable blink reflex of BEB is met by what is believed to be an adaptive decrease in the main-sequence slope that would decrease the strength of debilitating spasms. Collectively, these data extend the knowledge of the pathophysiology of BEB and, perhaps more important, establish the role of blink system plasticity in eyelid movement disorders.

Age-related changes in human blinks. Passive and active changes in eyelid kinematics

PURPOSE

The authors analyzed eyelid kinematics in normal aging subjects to test the hypothesis that eyelid movements exhibit age-related changes and that blink disorders prevalent among the elderly, in turn, represent an outcome of normal aging processes.

METHODS

The electromagnetic search coil technique was used to study blinks in normal human subjects for each decade from 40 to 89 years. Blink metrics (amplitude, peak velocity, and duration), main sequence relationships, and conjugacy were assessed.

RESULTS

Mean amplitude and peak velocity of blinks decreased with age for spontaneous blinks and, to a lesser extent, for voluntary blinks. Some but not all, of this decline could be attributed to a peripheral phenomenon, narrowed palpebral fissure width. The spontaneous blink down phase main sequence slope also declined with age. By contrast, blink rate and the coordination of movements of the two eyelids--blink conjugacy--exhibited no change.

CONCLUSIONS

These data demonstrate that disorders of blink systems typically seen in persons 50 years of age or older occur on a background of normal age-dependent changes in eyelid kinematics. Alterations in main sequence slope imply the operation of central adaptive systems during aging. Reduction in main sequence slope is interpreted as a reduction in aggregate orbicularis oculi motoneuron activity. Such a central neurologic adjustment in the motor output of blink systems may serve to compensate for an age-related increase in blink reflex excitability. Compensatory reduction in the main sequence relationship may offset a potentially hyperexcitable blink reflex, thereby reducing the likelihood of disorders such as blepharospasm. The authors conclude that although there are changes in the kinematics of blinking with age, such changes do not necessarily predispose an aging population to eyelid motility disorders.

Effects of gonadotropin-releasing hormone agonist (GnRHa) and ovariectomy on leukocyte subpopulations in rats with autotransplanted endometrium

PROBLEM

To determine the effect of estrogen deficiency on populations of immune cells in rats with autotransplanted endometrium.

METHOD OF STUDY

Autologous endometrial segments were implanted in the peritoneum of rats. Leukocyte subsets in the peripheral blood (PB) and peritoneal fluid (PF) of autotransplanted rats treated with gonadotropin-releasing hormone agonist (GnRHa) or ovariectomy were analyzed by flow cytometry.

RESULTS

Endometrial growth was suppressed in association with increases in natural killer (NK) cells and macrophages in rats treated surgically or medically after endometrial implantation compared with autotransplanted-only rats. Normal rats treated with GnRHa showed no significant alterations in PB and PF leukocyte subsets, even in NK cells and macrophages, compared with untreated normal rats.

CONCLUSIONS

Data suggest that GnRHa itself did not have an immunomodulating effect when rats were treated for 3 weeks, but that a hypoestrogenic state reduced the size of the ectopic endometrium in association with increases in NK cells and macrophages. Our findings support the hypothesis that ectopic endometrial cells may release immunosuppressive factors.