Activated STING in a vascular and pulmonary syndrome

BACKGROUND

The study of autoinflammatory diseases has uncovered mechanisms underlying cytokine dysregulation and inflammation.

METHODS

We analyzed the DNA of an index patient with early-onset systemic inflammation, cutaneous vasculopathy, and pulmonary inflammation. We sequenced a candidate gene, TMEM173, encoding the stimulator of interferon genes (STING), in this patient and in five unrelated children with similar clinical phenotypes. Four children were evaluated clinically and immunologically. With the STING ligand cyclic guanosine monophosphate-adenosine monophosphate (cGAMP), we stimulated peripheral-blood mononuclear cells and fibroblasts from patients and controls, as well as commercially obtained endothelial cells, and then assayed transcription of IFNB1, the gene encoding interferon-β, in the stimulated cells. We analyzed IFNB1 reporter levels in HEK293T cells cotransfected with mutant or nonmutant STING constructs. Mutant STING leads to increased phosphorylation of signal transducer and activator of transcription 1 (STAT1), so we tested the effect of Janus kinase (JAK) inhibitors on STAT1 phosphorylation in lymphocytes from the affected children and controls.

RESULTS

We identified three mutations in exon 5 of TMEM173 in the six patients. Elevated transcription of IFNB1 and other gene targets of STING in peripheral-blood mononuclear cells from the patients indicated constitutive activation of the pathway that cannot be further up-regulated with stimulation. On stimulation with cGAMP, fibroblasts from the patients showed increased transcription of IFNB1 but not of the genes encoding interleukin-1 (IL1), interleukin-6 (IL6), or tumor necrosis factor (TNF). HEK293T cells transfected with mutant constructs show elevated IFNB1 reporter levels. STING is expressed in endothelial cells, and exposure of these cells to cGAMP resulted in endothelial activation and apoptosis. Constitutive up-regulation of phosphorylated STAT1 in patients' lymphocytes was reduced by JAK inhibitors.

CONCLUSIONS

STING-associated vasculopathy with onset in infancy (SAVI) is an autoinflammatory disease caused by gain-of-function mutations in TMEM173. (Funded by the Intramural Research Program of the National Institute of Arthritis and Musculoskeletal and Skin Diseases; ClinicalTrials.gov number, NCT00059748.).

Tumor microsatellite instability and clinical outcome in young patients with colorectal cancer

BACKGROUND

Colorectal cancer can arise through two distinct mutational pathways: microsatellite instability or chromosomal instability. We tested the hypothesis that colorectal cancers arising from the microsatellite-instability pathway have distinctive clinical attributes that affect clinical outcome.

METHODS

We tested specimens of colorectal cancer from a population-based series of 607 patients (50 years of age or younger at diagnosis) for microsatellite instability. We compared the clinical features and survival of patients who had colorectal cancer characterized by high-frequency microsatellite instability with these characteristics in patients who had colorectal cancers with microsatellite stability.

RESULT

We found high-frequency microsatellite instability in 17 percent of the colorectal cancers in 607 patients, and in a multivariate analysis, microsatellite instability was associated with a significant survival advantage independently of all standard prognostic factors, including tumor stage (hazard ratio, 0.42; 95 percent confidence interval, 0.27 to 0.67; P< 0.001). Furthermore, regardless of the depth of tumor invasion, colorectal cancers with high-frequency microsatellite instability had a decreased likelihood of metastasizing to regional lymph nodes (odds ratio, 0.33; 95 percent confidence interval, 0.21 to 0.53; P< 0.001) or distant organs (odds ratio, 0.49; 95 percent confidence interval, 0.27 to 0.89; P=0.02).

CONCLUSION

High-frequency microsatellite instability in colorectal cancer is independently predictive of a relatively favorable outcome and, in addition, reduces the likelihood of metastases.

Dye efflux studies suggest that hematopoietic stem cells expressing low or undetectable levels of CD34 antigen exist in multiple species

We previously described a method for isolating murine hematopoietic stem cells capable of reconstituting lethally irradiated recipients, which depends solely on dual-wavelength flow cytometric analysis of murine bone marrow cells stained with the fluorescent DNA-binding dye Hoechst 33342. This method, which appears to rely on the differential ability of stem cells to efflux the Hoechst dye, defines an extremely small and homogeneous population of cells (termed SP cells). We show here that dual-wavelength analysis of Hoechst dye-stained human, rhesus and miniature swine bone marrow cells reveals a small, distinct population of cells that efflux the dye in a manner identical to murine SP cells. Like the murine SP cells, both human and rhesus SP cells are primarily CD34-negative and lineage marker-negative. In vitro culture studies demonstrated that rhesus SP cells are highly enriched for long-term culture-initiating cells (LTC-ICs), an indicator of primitive hematopoietic cells, and have the capacity for differentiation into T cells. Although rhesus SP cells do not initially possess any hematopoietic colony-forming capability, they acquire the ability to form colonies after long-term culture on bone marrow stroma, coincident with their conversion to a CD34-positive phenotype. These studies suggest the existence of a hitherto unrecognized population of hematopoietic stem cells that lack the CD34 surface marker classically associated with primitive hematopoietic cells.

Crystal structure of the cytochrome bc1 complex from bovine heart mitochondria

On the basis of x-ray diffraction data to a resolution of 2.9 angstroms, atomic models of most protein components of the bovine cytochrome bc1 complex were built, including core 1, core 2, cytochrome b, subunit 6, subunit 7, a carboxyl-terminal fragment of cytochrome c1, and an amino-terminal fragment of the iron-sulfur protein. The positions of the four iron centers within the bc1 complex and the binding sites of the two specific respiratory inhibitors antimycin A and myxothiazol were identified. The membrane-spanning region of each bc1 complex monomer consists of 13 transmembrane helices, eight of which belong to cytochrome b. Closely interacting monomers are arranged as symmetric dimers and form cavities through which the inhibitor binding pockets can be accessed. The proteins core 1 and core 2 are structurally similar to each other and consist of two domains of roughly equal size and identical folding topology.

Histochemical and ultrastructural demonstration of gamma-glutamyl transpeptidase activity

A simultaneous coupling azo dye method for the histochemical demonstration of γ-glutamyl transpeptidase activity using the new substrate γ-glutamyl-4-methoxy-2-naphthylamide has been described. The method appears superior to previously reported methods for γ-glutamyl transpeptidase activity and can easily be modified for the electron microscopic localization of the enzyme by bridging osmium to the copper chelate of the azo dye via thiocarbohydrazide. The optimum conditions for the histochemical reaction were developed and the distribution of enzymatic activity in the tissues of the rat is described for light microscopy and with rat pancreas for electron microscopy. The electron-opaque deposits were seen in the endoplasmic reticulum in the vicinity of the zymogen granules in the apical portion of the acinar cell.

MADR2 maps to 18q21 and encodes a TGFbeta-regulated MAD-related protein that is functionally mutated in colorectal carcinoma

The MAD-related (MADR) family of proteins are essential components in the signaling pathways of serine/threonine kinase receptors for the transforming growth factor beta (TGFbeta) superfamily. We demonstrate that MADR2 is specifically regulated by TGFbeta and not bone morphogenetic proteins. The gene for MADR2 was found to reside on chromosome 18q21, near DPC4, another MADR protein implicated in pancreatic cancer. Mutational analysis of MADR2 in sporadic tumors identified four missense mutations in colorectal carcinomas, two of which display a loss of heterozygosity. Biochemical and functional analysis of three of these demonstrates that the mutations are inactivating. These findings suggest that MADR2 is a tumor suppressor and that mutations acquired in colorectal carcinomas may function to disrupt TGFbeta signaling.

The full-length leptin receptor has signaling capabilities of interleukin 6-type cytokine receptors

The leptin receptor (OB-R) is a single membrane-spanning protein that mediates the weight regulatory effects of leptin (OB protein). The mutant allele (db) of the OB-R gene encodes a protein with a truncated cytoplasmic domain that is predicted to be functionally inactive. Several mRNA splice variants encoding OB-Rs with different length cytoplasmic domains have been detected in various tissues. Here we demonstrate that the full-length OB-R (predominantly expressed in the hypothalamus), but not a major naturally occurring truncated form or a mutant from found in db/db mice, can mediate activation of signal transducer and activator of transcription (STAT) proteins and stimulate transcription through interleukin 6 responsive gene elements. Reconstitution experiments suggest that, although OB-R mediates intracellular signals with a specificity similar to interleukin 6-type cytokine receptors, signaling appears to be independent of the gp130 signal transducing component of the interleukin 6-type cytokine receptors.

Phylogenetic affiliation of the pseudomonads based on 16S rRNA sequence

The broad and vague phenotypic definition allowed the genus Pseudomonas to become a dumping ground for incompletely characterized polarly flagellated, gram-negative, rod-shaped, aerobic bacteria, and a large number of species have been accommodated in the genus Pseudomonas. The 16S rRNA sequences of 128 valid and invalid Pseudomonas species, which included almost valid species of the genus Pseudomonas listed in the Approved Lists of Bacterial Names, were obtained: sequences of 59 species were determined and those of 69 species were obtained from the GenBank/EMBL/DDBJ databases. These sequences were compared with the sequences of other species of the Proteobacteria. Fifty-seven valid or invalid species including Pseudomonas aeruginosa (type species of the genus Pseudomonas Migula 1894) belonged to the genus Pseudomonas (sensu stricto). Seven subclusters were formed in the cluster of the genus Pseudomonas (sensu stricto), and the resulting clusters conformed well to the rRNA-DNA hybridization study by Palleroni (1984). The other species did not belong to the genus Pseudomonas (sensu stricto) and were related to other genera, which were placed in four subclasses of the Proteobacteria (alpha, beta, gamma and gamma-beta subclasses). Twenty-six examined species, which were not included in the cluster of the Pseudomonas (sensu stricto) and have not been transferred to other genera as yet, are listed alphabetically: 'Pseudomonas abikonensis', Pseudomonas antimicrobica, Pseudomonas beijerinckii, Pseudomonas beteli, Pseudomonas boreopolis, 'Pseudomonas butanovora', Pseudomonas carboxydohydrogena, Pseudomonas cissicola, Pseudomonas doudoroffii, Pseudomonas echinoides, Pseudomonas elongata, Pseudomonas flectens, Pseudomonas geniculata, Pseudomonas halophila, Pseudomonas hibiscicola, Pseudomonas huttiensis, Pseudomonas iners, Pseudomonas lanceolata, Pseudomonas lemoignei, Pseudomonas mephitica, Pseudomonas pictorum, Pseudomonas saccharophila, Pseudomonas spinosa, Pseudomonas stanier, Pseudomonas syzygii and Pseudomonas woodsii. The phylogenetic affiliations of these 26 pseudomonads species are shown.

Allelic loss of chromosome 18q and prognosis in colorectal cancer

BACKGROUND

Colorectal cancer occurs in approximately 150,000 people each year in the United States. Prognostic assessment influences the treatment of patients with colorectal cancer, including decisions about adjuvant therapy. We evaluated chromosome 18q allelic loss, a genetic event associated with tumor progression, as a prognostic marker for this disease.

METHODS

We developed procedures to examine the status of chromosome 18q with microsatellite markers and DNA from formalin-fixed, paraffin-embedded tumors. Allelic loss of chromosome 18q was assessed in 145 consecutively resected stage II or III colorectal carcinomas.

RESULTS

Among patients with stage II disease, the five-year survival rate was 93 percent in those whose tumor had no evidence of allelic loss of chromosome 18q and 54 percent in those with allelic loss; among patients with stage III disease, survival was 52 and 38 percent, respectively. The overall estimated hazard ratio for death in patients whose tumor had chromosome 18q allelic loss was 2.83 (P = 0.008) according to univariate analysis. Furthermore, chromosome 18q allelic loss remained a strong predictive factor (hazard ratio for death, 2.46; 95 percent confidence interval, 1.06 to 5.71; P = 0.036) after adjustment for all other evaluated factors, including tumor differentiation, vein invasion, and TNM stage.

CONCLUSIONS

The status of chromosome 18q has strong prognostic value in patients with stage II colorectal cancer. The prognosis in patients with stage II cancer and chromosome 18q allelic loss is similar to that in patients with stage III cancer, who are thought to benefit from adjuvant therapy. In contrast, patients with stage II disease who do not have chromosome 18q allelic loss in their tumor have a survival rate similar to that of patients with stage I disease and may not require additional therapy.

The periodic association of MAP2 with brain microtubules in vitro

Several high molecular weight polypeptides have been shown to quantitatively copurify with brain tubulin during cycles of in vitro assembly-disassembly. These microtubule-associated proteins (MAPs) have been shown to influence the rate and extent of microtubule assembly in vitro. We report here that a heat-stable fraction highly enriched for one of the MAPs, MAP2 (mol wt approximately 300,000 daltons), devoid of MAP1 (mol wt approximately 350,000 daltons), has been purified from calf neurotubules. This MAP2 fraction stoichiometrically promotes microtubule assembly, lowering the critical concentration for tubulin assembly to 0.05 mg/ml. Microtubules saturated with MAP2 contain MAP2 and tubulin in a molar ratio of approximately 1 mole of MAP2 to 9 moles of tubulin dimer. Electron microscopy of thin sections of the MAP2-saturated microtubules fixed in the presence of tannic acid demonstrates a striking axial periodicity of 32 +/- 8 nm.

The landscape and therapeutic relevance of cancer-associated transcript fusions

Transcript fusions as a result of chromosomal rearrangements have been a focus of attention in cancer as they provide attractive therapeutic targets. To identify novel fusion transcripts with the potential to be exploited therapeutically, we analyzed RNA sequencing, DNA copy number and gene mutation data from 4,366 primary tumor samples. To avoid false positives, we implemented stringent quality criteria that included filtering of fusions detected in RNAseq data from 364 normal tissue samples. Our analysis identified 7,887 high confidence fusion transcripts across 13 tumor types. Our fusion prediction was validated by evidence of a genomic rearrangement for 78 of 79 fusions in 48 glioma samples where whole genome sequencing data was available. Cancers with higher levels of genomic instability showed a corresponding increase in fusion transcript frequency, whereas tumor samples harboring fusions contained statistically significantly fewer driver gene mutations, suggesting an important role for tumorigenesis. We identified at least one in-frame protein kinase fusion in 324 of 4,366 samples (7.4%). Potentially druggable kinase fusions involving ALK, ROS, RET, NTRK, and FGFR gene families were detected in bladder carcinoma (3.3%), glioblastoma (4.4%), head and neck cancer (1.0%), low grade glioma (1.5%), lung adenocarcinoma (1.6%), lung squamous cell carcinoma (2.3%), and thyroid carcinoma (8.7%), suggesting a potential for application of kinase inhibitors across tumor types. In-frame fusion transcripts involving histone methyltransferase or histone demethylase genes were detected in 111 samples (2.5%) and may additionally be considered as therapeutic targets. In summary, we described the landscape of transcript fusions detected across a large number of tumor samples and revealed fusion events with clinical relevance that have not been previously recognized. Our results support the concept of basket clinical trials where patients are matched with experimental therapies based on their genomic profile rather than the tissue where the tumor originated.

Malignant lymphoma, lymphoblastic

Among the malignant lymphomas of the diffuse, poorly differentiated lymphocytic type, a cytologically distinctive form can be recognized. It is composed of immature lymphoid cells that are indistinguishable from the cells of acute lymphoblastic leukemia (ALL). Although these neoplasms usually have been classified as malignant lymphoma, lymphoblastic type, they contain, in addition to lymphoblasts, prolymphocytes in varying proportions. On the basis of the nuclear morphology, malignant lymphoma of the lymphoblastic type, (MLLB) can be further divided into those with and those without convoluted nuclei. In our series both groups had the following clinical features in common: 1) frequent occurrence in children and adolescents; 2) clinical presentation with mediastinal masses in 50% of cases; 3) a high incidence of bone marrow and perpheral blood involvement during the course of the disease; and 4) rapid progression of the disease with a median survival of 8 months. Our observations indicate that nuclear convolutions are helpful but not essential for the recognition of a clinicopathologic entity which is histologically and cytologically characterized by 1) the immaturity of the lymphoid cells indistinguishable from the lymphoblasts and prolymphocytes of ALL and 2) a high mitotic index. Because of the frequency with which MLLB progresses into ALL, systemic therapy may be indicated even before this progression is hematologically evident. This indicates the need for morphologic recognition of this malignant lymphoma regardless of the presence of nuclear convolution, age of the patient, and site of presentation.

Nasal obstruction as a risk factor for sleep-disordered breathing. The University of Wisconsin Sleep and Respiratory Research Group

Nasal obstruction frequently has been associated with sleep-disordered breathing as a potential etiologic factor. Nasal obstruction results in pathologic changes in airflow velocity and resistance. Experimentally produced nasal obstruction increases resistance and leads to sleep-disordered breathing events, including apnea, hypopnea, and snoring. Clinical research examining the correlation between nasal obstruction and sleep-disordered breathing is limited, especially in regard to patients with conditions that increase nasal resistance, such as rhinitis and sinusitis. To further identify risk factors for sleep-disordered breathing, the role of chronic and acute nasal congestion was investigated in a population-based sample. Data on nasal congestion history and sleep problems were obtained by questionnaire (n = 4927) and by objective inlaboratory measurement (n = 911). Participants who often or almost always experienced nighttime symptoms of rhinitis (5 or more nights a month) were significantly (p < 0.0001) more likely to report habitual snoring (3 to 7 nights a week), chronic excessive daytime sleepiness, or chronic nonrestorative sleep than were those who rarely or never had symptoms. Habitual snorers had significantly (p < 0.02) lower air flow than nonsnorers, although a linear relation between decreased airflow and sleep-disordered breathing severity did not exist. Participants who reported nasal congestion due to allergy were 1.8 times more likely to have moderate to severe sleep-disordered breathing than were those without nasal congestion due to allergy. Men and women with nasal obstruction, especially chronic nighttime symptoms of rhinitis, are significantly more likely to be habitual snorers, and a proportion also may have frequent episodes of apnea and hypopnea, indicative of severe sleep-disordered breathing. Because allergic rhinitis is a common cause of nasal obstruction and it is a modifiable risk factor, further study of this association is warranted.

Prevention of pulmonary morbidity for patients with Duchenne muscular dystrophy

STUDY OBJECTIVE

To evaluate the effects of a new respiratory management protocol on respiratory morbidity and hospitalization rates for patients with Duchenne muscular dystrophy (DMD).

DESIGN

A retrospective cohort study.

METHODS

Using a protocol in which oxyhemoglobin desaturation was prevented or reversed by the use of noninvasive intermittent positive pressure ventilation (IPPV) and assisted coughing as needed, the hospitalization rates and days for 24 protocol DMD ventilator users were compared with those of 22 nonprotocol DMD tracheostomy IPPV users.

RESULTS

The 22 conventionally managed patients were hospitalized a mean of 72.2+/-112 days when undergoing tracheostomy. This included a 16.1+/-5.4-day period of translaryngeal intubation. The 24 protocol patients were hospitalized a mean of 6.0+/-2.4 days (p<0.005) when beginning ventilator use. Over their next 126.2 patient-years of ventilator use, the 24 protocol patients had significantly lower rates of hospitalization (p<0.008) and hospitalization days (p<0.005) than had the tracheostomy IPPV users over a 167.2 patient-year period. This is true although 14 of the 24 protocol patients went on to require 24-h noninvasive IPPV for 4.5+/-3.6 years. Five of the 14 have yet to be hospitalized.

CONCLUSION

The use of inspiratory and expiratory aids can prolong survival while significantly decreasing the pulmonary morbidity and hospitalization rates associated with conventional resort to tracheostomy IPPV.

Malignant histiocytosis (histiocytic medullary reticulosis). I. Clinicopatholigic study of 29 cases

The clinical records and histologic material from 29 cases of malignant histiocytosis (MH) have been reviewed, as well as autopsy findings in 14 cases. The mean age was 31 years, with a 2.2:1 male to female preponderance. Major physical findings included temperature elevation, lymphadenopathy, hepatomegaly, splenomegaly, and preterminal jaundice. Common laboratory findings were anemia, leukopenia, and thrombocytopenia. The median survival was 6 months, the mean 14 months, and the range from 1 month to 8 years. The histologic features observed in lymph nodes, liver, spleen, and bone marrow have been emphasized, as well as features useful in differential diagnosis. In contrast to our experience with the non-Hodgkin's lymphomas, bone marrow aspiration was superior to biopsy in assessing marrow involvement. Unusual manifestations included soft tissue infiltration in 5 cases; 2 of these patients presented with a soft tissue mass. The distinctive clinical as well as histologic findings warrant recognition and separation of MH from other hematopoietic disorders.

Cellular morphogenesis in the Saccharomyces cerevisiae cell cycle: localization of the CDC3 gene product and the timing of events at the budding site

Budding cells of the yeast Saccharomyces cerevisiae possess a ring of 10-nm-diameter filaments, of unknown biochemical nature, that lies just inside the plasma membrane in the neck connecting the mother cell to its bud. Electron microscopic observations suggest that these filaments assemble at the budding site coincident with bud emergence and disassemble shortly before cytokinesis (Byers, B. and L. Goetsch. 1976. J. Cell Biol. 69:717-721). Mutants defective in any of four genes (CDC3, CDC10, CDC11, or CDC12) lack these filaments and display a pleiotropic phenotype that involves abnormal bud growth and an inability to complete cytokinesis. We showed previously by immunofluorescence that the CDC12 gene product is probably a constituent of the ring of 10-nm filaments (Haarer, B. and J. Pringle. 1987. Mol. Cell. Biol. 7:3678-3687). We now report the use of fusion proteins to generate polyclonal antibodies specific for the CDC3 gene product. In immunofluorescence experiments, these antibodies decorated the neck regions of wild-type and mutant cells in patterns suggesting that the CDC3 gene product is also a constituent of the ring of 10-nm filaments. We also used the CDC3-specific and CDC12-specific antibodies to investigate the timing of localization of these proteins to the budding site. The results suggest that the CDC3 protein is organized into a ring at the budding site well before bud emergence and remains so organized for some time after cytokinesis. The CDC12 product appears to behave similarly, but may arrive at the budding site closer to the time of bud emergence, and disappear from that site more quickly after cytokinesis, than does the CDC3 product. Examination of mating cells and cells responding to purified mating pheromone revealed novel arrangements of the CDC3 and CDC12 products in the regions of cell wall reorganization. Both proteins were present in normal-looking ring structures at the bases of the first zygotic buds.

A functional bone morphogenetic protein system in the ovary

Bone morphogenetic proteins (BMPs) comprise a large group of polypeptides in the transforming growth factor beta superfamily with essential physiological functions in morphogenesis and organogenesis in both vertebrates and invertebrates. At present, the role of BMPs in the reproductive system of any species is poorly understood. Here, we have established the existence of a functional BMP system in the ovary, replete with ligand, receptor, and novel cellular functions. In situ hybridization histochemistry identified strong mRNA labeling for BMP-4 and -7 in the theca cells and BMP receptor types IA, IB, and II in the granulosa cells and oocytes of most follicles in ovaries of normal cycling rats. To explore the paracrine function of this BMP system, we examined the effects of recombinant BMP-4 and -7 on FSH (follicle-stimulating hormone)-induced rat granulosa cytodifferentiation in serum-free medium. Both BMP-4 and -7 regulated FSH action in positive and negative ways. Specifically, physiological concentrations of the BMPs enhanced and attenuated the stimulatory action of FSH on estradiol and progesterone production, respectively. These effects were dose- and time-dependent. Furthermore, the BMPs increased granulosa cell sensitivity to FSH. Thus, BMPs have now been identified as molecules that differentially regulate FSH-dependent estradiol and progesterone production in a way that reflects steroidogenesis during the normal estrous cycle. As such, it can be hypothesized that BMPs might be the long-sought "luteinization inhibitor" in Graafian follicles during their growth and development.

Twisted gastrulation is a conserved extracellular BMP antagonist

Bone morphogenetic protein (BMP) signalling regulates embryonic dorsal-ventral cell fate decisions in flies, frogs and fish. BMP activity is controlled by several secreted factors including the antagonists chordin and short gastrulation (SOG). Here we show that a second secreted protein, Twisted gastrulation (Tsg), enhances the antagonistic activity of Sog/chordin. In Drosophila, visualization of BMP signalling using anti-phospho-Smad staining shows that the tsg and sog loss-of-function phenotypes are very similar. In S2 cells and imaginal discs, TSG and SOG together make a more effective inhibitor of BMP signalling than either of them alone. Blocking Tsg function in zebrafish with morpholino oligonucleotides causes ventralization similar to that produced by chordin mutants. Co-injection of sub-inhibitory levels of morpholines directed against both Tsg and chordin synergistically enhances the penetrance of the ventralized phenotype. We show that Tsgs from different species are functionally equivalent, and conclude that Tsg is a conserved protein that functions with SOG/chordin to antagonize BMP signalling.

Mechanisms of action of the soy isoflavone genistein: emerging role for its effects via transforming growth factor beta signaling pathways

The soy isoflavone genistein attenuates growth factor- and cytokine-stimulated proliferation of both normal and cancer cells. This article reviews our current understanding of the potential mechanisms of action of genistein. In membrane preparations from mammalian cells, genistein is a potent and specific inhibitor of tyrosine autophosphorylation of the epidermal growth factor (EGF) receptor. However, in several cell systems in which it inhibits growth, genistein does not alter tyrosine phosphorylation of the EGF receptor or other tyrosine kinase substrates thought to be involved in signal transduction pathways, suggesting that other mechanisms may be responsible for its action. Alternatives include inhibition of DNA topoisomerase II activity, regulation of cell cycle checkpoints, and antiangiogenic and antioxidant activity. Experiments in our laboratory suggest a new concept, that genistein may inhibit cell growth by modulating transforming growth factor (TGF) beta1 signaling pathways. Such a link between genistein action and TGFbeta1 function is supported by preliminary results of studies in patients with hereditary hemorrhagic telangiectasia (a genetic disorder involving mutations in proteins that regulate TGFbeta receptor complex formation and signaling) in which several patients had dramatic attenuation of their symptoms after 1 wk of ingesting soy-based beverages. These preclinical studies in combination with our cell culture data suggest that the mechanism of genistein involves, if not requires, TGFbeta1-signaling.

Emerging invasive liver abscess caused by K1 serotype Klebsiella pneumoniae in Korea

OBJECTIVES

The high incidence of invasive liver abscess caused by Klebsiella pneumoniae in Taiwan, contrasted with the rareness of this disease in Western countries, has aroused special interest. There have been few detailed reports from other Asian countries. To investigate a current epidemiology of K. pneumoniae liver abscess in Korea and to determine K serotype distribution in K. pneumoniae strains causing liver abscess, we performed a nationwide prospective study.

METHODS

Community-acquired, culture-proven liver abscess cases were enrolled between 2004 and 2005. Etiologies and clinical features were analyzed. K. pneumoniae isolates were serotyped according to K antigen. Meta-analysis was done to determine the time trend of the etiologies of liver abscess in Korea.

RESULTS

Out of 371 cases collected prospectively, 290 (78.2%) were caused by K. pneumoniae. Most K. pneumoniae liver abscesses were monomicrobial. Diabetes mellitus was the most common underlying disease (39.9%). Distant metastatic infections were frequently observed (8.7%). magA PCR revealed that 95 (59.4%) out of 160 K. pneumoniae isolates belonged to the K1 serotype.

CONCLUSIONS

Our study indicates that K. pneumoniae has emerged as a major etiologic agent of liver abscess in Korea, and these emerging infections seem to be attributable to invasive K. pneumoniae strains with capsular K1 serotype.

Inhibitor binding changes domain mobility in the iron-sulfur protein of the mitochondrial bc1 complex from bovine heart

We have analyzed crystal structures of cytochrome bc1 complexes with electron transfer inhibitors bound to the ubiquinone binding pockets Qi and/or Qo in the cytochrome b subunit. The presence or absence of the Qi inhibitor antimycin A did not affect the binding of the Qo inhibitors. Different subtypes of Qo inhibitors had dramatically different effects on the mobility of the extramembrane domain of the iron-sulfur protein (ISP): Binding of 5-undecyl-6-hydroxy-4, 7-dioxobenzothiazol and stigmatellin (subtype Qo-II and Qo-III, respectively) led to a fixation of the ISP domain on the surface of cytochrome b, whereas binding of myxothiazol and methoxyacrylate-stilbene (subtype Qo-I) favored release of this domain. The native structure has an empty Qo pocket and is intermediate between these extremes. On the basis of these observations we propose a model of quinone oxidation in the bc1 complex, which incorporates fixed and loose states of the ISP as features important for electron transfer and, possibly, also proton transport.

Inhibition of monoamine oxidase A by beta-carboline derivatives

beta-Carbolines are endogenous inhibitors of monoamine oxidase (MAO). The interaction of nine beta-carboline derivatives and four 3,4-dihydro forms with purified MAO A was investigated. All the compounds tested were reversible competitive inhibitors selective for MAO A, in agreement with previous studies on membrane preparations. The oxidation of kynuramine by MAO A in the presence of the more effective inhibitors showed a lag period before reaching the steady state. In general, the 1-methyl and 7-methoxy substituents increased the potency. Harmine, 2-methylharminium, 2,9-dimethylharminium, and harmaline were the most effective inhibitors of the purified MAO A, with low Ki values of 5, 69, 15, and 48 nM, respectively. The inhibitors interacted with the covalently bound flavin to induce distinct spectral changes, the magnitude of which correlated with the efficacy of the inhibition. The more effective inhibitors could be in situ inhibitors of MAO A.

Synthesis and degradation of cyclic ADP-ribose by NAD glycohydrolases

Cyclic adenosine diphosphoribose (cADPR), a recently discovered metabolite of nicotinamide adenine dinucleotide (NAD), is a potent calcium-releasing agent postulated to be a new second messenger. An enzyme that catalyzes the synthesis of cADPR from NAD and the hydrolysis of cADPR to ADP-ribose (ADPR) was purified to homogeneity from canine spleen microsomes. The net conversion of NAD to ADPR categorizes this enzyme as an NAD glycohydrolase. NAD glycohydrolases are ubiquitous membrane-bound enzymes that have been known for many years but whose function has not been identified. The results presented here suggest that these enzymes may function in the regulation of calcium homeostasis by the ability to synthesize and degrade cADPR.