Authors: Rajesh M, Bátkai S, Kechrid M, Mukhopadhyay P, Lee WS, Horváth B, Holovac E, Cinar R, Liaudet L, Mackie K, Haskó G, Pacher P
Journal: Diabetes. 2012 Feb 7. [Epub ahead of print]
Endocannabinoids and cannabinoid 1 (CB(1)) receptors have been implicated in cardiac dysfunction, inflammation, and cell death associated with various forms of shock, heart failure, and atherosclerosis, in addition to their recognized role in the development of various cardiovascular risk factors in obesity/metabolic syndrome and diabetes. In this study, we explored the role of CB(1) receptors in myocardial dysfunction, inflammation, oxidative/nitrative stress, cell death, and interrelated signaling pathways, using a mouse model of type 1 diabetic cardiomyopathy. Diabetic cardiomyopathy was characterized by increased myocardial endocannabinoid anandamide levels, oxidative/nitrative stress, activation of p38/Jun NH(2)-terminal kinase (JNK) mitogen-activated protein kinases (MAPKs), enhanced inflammation (tumor necrosis factor-α, interleukin-1β, cyclooxygenase 2, intracellular adhesion molecule 1, and vascular cell adhesion molecule 1), increased expression of CB(1), advanced glycation end product (AGE) and angiotensin II type 1 receptors (receptor for advanced glycation end product [RAGE], angiotensin II receptor type 1 [AT(1)R]), p47(phox) NADPH oxidase subunit, β-myosin heavy chain isozyme switch, accumulation of AGE, fibrosis, and decreased expression of sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase (SERCA2a). Pharmacological inhibition or genetic deletion of CB(1) receptors attenuated the diabetes-induced cardiac dysfunction and the above-mentioned pathological alterations. Activation of CB(1) receptors by endocannabinoids may play an important role in the pathogenesis of diabetic cardiomyopathy by facilitating MAPK activation, AT(1)R expression/signaling, AGE accumulation, oxidative/nitrative stress, inflammation, and fibrosis. Conversely, CB(1) receptor inhibition may be beneficial in the treatment of diabetic cardiovascular complications.
Authors: Li M, He Y, Dubois W, Wu X, Shi J, Huang J
Journal: Mol Cell. 2012 Feb 29
p53 is critical in regulating the differentiation of ES and induced pluripotent stem (iPS) cells. Here, we report a whole-genome study of p53-mediated DNA damage signaling in mouse ES cells. Systems analyses reveal that binding of p53 at the promoter region significantly correlates with gene activation but not with repression. Unexpectedly, we identify a regulatory mode for p53-mediated repression through interfering with distal enhancer activity. Importantly, many ES cell-enriched core transcription factors are p53-repressed genes. Further analyses demonstrate that p53-repressed genes are functionally associated with ES/iPS cell status while p53-activated genes are linked to differentiation. p53-activated genes and -repressed genes also display distinguishable features of expression levels and epigenetic markers. Upon DNA damage, p53 regulates the self-renewal and pluripotency of ES cells. Together, these results support a model where, in response to DNA damage, p53 affects the status of ES cells through activating differentiation-associated genes and repressing ES cell-enriched genes.
Authors: Xekouki P, Hatch MM, Lin L, Rodrigo DA, Azevedo M, Sierra MD, Levy I, Saloustros E, Moraitis A, Horvath A, Kebebew E, Hoffman D, Stratakis CA
Journal: Endocr Relat Cancer. 2012 Feb 9. [Epub ahead of print]
KCNJ5 mutations were recently described in primary hyperaldosteronism (PH or Conn syndrome). The frequency of these mutations in PH and the way KCNJ5 defects cause disease remain unknown.A total of 53 patients with PH have been seen at the National Institutes of Health (NIH) over the last 12 years. Their peripheral and tumor DNA (the latter from 16 that were operated) was screened for KCNJ5 mutations; functional studies of the identified defects were done after transient transfection. Only 2 mutations were identified, both in the tumor DNA only. There were no germline sequencing defects in any of the patients except for known synonymous variants of the KCNJ5 gene. One mutation was the previously described c.G451C alteration; the other was a novel one in the same codon: c.G451A; both lead to the same amino acid substitution (G151R) in the KCNJ5 protein. Functional studies confirmed previous findings: both mutations caused loss of channel selectivity and a positive shift in the reversal potential. The KCNJ5 protein was strongly expressed in the zona glomerulosa of normal adrenal glands but showed variable expression in the APAs with mutation and without.The rate of KCNJ5 mutations among patients with PH and/or their tumors is substantially lower than what was previously reported. The G151R amino acid substitution appears to be the only one so far detected in PH, despite additional nucleotide changes. The mutation causes loss of this potassium channel's selectivity and may assist in the design of new therapies for PH.
Authors: García M, Cooper A, Shi W, Bornmann W, Carrion R, Kalman D, Nabel GJ
Journal: Sci Transl Med. 2012 Feb 29;4(123):123ra24. doi: 10.1126/scitranslmed.3003500
Ebola virus causes a fulminant infection in humans resulting in diffuse bleeding, vascular instability, hypotensive shock, and often death. Because of its high mortality and ease of transmission from human to human, Ebola virus remains a biological threat for which effective preventive and therapeutic interventions are needed. An understanding of the mechanisms of Ebola virus pathogenesis is critical for developing antiviral therapeutics. Here, we report that productive replication of Ebola virus is modulated by the c-Abl1 tyrosine kinase. Release of Ebola virus-like particles (VLPs) in a cell culture cotransfection system was inhibited by c-Abl1-specific small interfering RNA (siRNA) or by Abl-specific kinase inhibitors and required tyrosine phosphorylation of the Ebola matrix protein VP40. Expression of c-Abl1 stimulated an increase in phosphorylation of tyrosine 13 (Y(13)) of VP40, and mutation of Y(13) to alanine decreased the release of Ebola VLPs. Productive replication of the highly pathogenic Ebola virus Zaire strain was inhibited by c-Abl1-specific siRNAs or by the Abl-family inhibitor nilotinib by up to four orders of magnitude. These data indicate that c-Abl1 regulates budding or release of filoviruses through a mechanism involving phosphorylation of VP40. This step of the virus life cycle therefore may represent a target for antiviral therapy.
Authors: Noinaj N, Easley NC, Oke M, Mizuno N, Gumbart J, Boura E, Steere AN, Zak O, Aisen P, Tajkhorshid E, Evans RW, Gorringe AR, Mason AB, Steven AC, Buchanan SK
Journal: Nature. 2012 Feb 12. doi: 10.1038/nature10823. [Epub ahead of print]
Neisseria are obligate human pathogens causing bacterial meningitis, septicaemia and gonorrhoea. Neisseria require iron for survival and can extract it directly from human transferrin for transport across the outer membrane. The transport system consists of TbpA, an integral outer membrane protein, and TbpB, a co-receptor attached to the cell surface; both proteins are potentially important vaccine and therapeutic targets. Two key questions driving Neisseria research are how human transferrin is specifically targeted, and how the bacteria liberate iron from transferrin at neutral pH. To address these questions, we solved crystal structures of the TbpA-transferrin complex and of the corresponding co-receptor TbpB. We characterized the TbpB-transferrin complex by small-angle X-ray scattering and the TbpA-TbpB-transferrin complex by electron microscopy. Our studies provide a rational basis for the specificity of TbpA for human transferrin, show how TbpA promotes iron release from transferrin, and elucidate how TbpB facilitates this process.
Authors: Bolton KL, Chenevix-Trench G, Goh C, Sadetzki S, Ramus SJ, Karlan BY, Lambrechts D, Despierre E, Barrowdale D, McGuffog L, Healey S, Easton DF, Sinilnikova O, Benítez J, García MJ, Neuhausen S, Gail MH, Hartge P, Peock S, Frost D, Evans DG, Eeles R, Godwin AK, Daly MB, Kwong A, Ma ES, Lázaro C, Blanco I, Montagna M, D'Andrea E, Nicoletto MO, Johnatty SE, Kjær SK, Jensen A, Høgdall E, Goode EL, Fridley BL, Loud JT, Greene MH, Mai PL, Chetrit A, Lubin F, Hirsh-Yechezkel G, Glendon G, Andrulis IL, Toland AE, Senter L, Gore ME, Gourley C, Michie CO, Song H, Tyrer J, Whittemore AS, McGuire V, Sieh W, Kristoffersson U, Olsson H, Borg Å, Levine DA, Steele L, Beattie MS, Chan S, Nussbaum RL, Moysich KB, Gross J, Cass I, Walsh C, Li AJ, Leuchter R, Gordon O, Garcia-Closas M, Gayther SA, Chanock SJ, Antoniou AC, Pharoah PD; EMBRACE; kConFab Investigators; Cancer Genome Atlas Research Network
Journal: JAMA. 2012 Jan 25;307(4):382-90.
CONTEXT: Approximately 10% of women with invasive epithelial ovarian cancer (EOC) carry deleterious germline mutations in BRCA1 or BRCA2. A recent article suggested that BRCA2-related EOC was associated with an improved prognosis, but the effect of BRCA1 remains unclear.
OBJECTIVE: To characterize the survival of BRCA carriers with EOC compared with noncarriers and to determine whether BRCA1 and BRCA2 carriers show similar survival patterns.
DESIGN, SETTING, AND PARTICIPANTS: A pooled analysis of 26 observational studies on the survival of women with ovarian cancer, which included data from 1213 EOC cases with pathogenic germline mutations in BRCA1 (n = 909) or BRCA2 (n = 304) and from 2666 noncarriers recruited and followed up at variable times between 1987 and 2010 (the median year of diagnosis was 1998).
MAIN OUTCOME MEASURE: Five-year overall mortality.
RESULTS: The 5-year overall survival was 36% (95% CI, 34%-38%) for noncarriers, 44% (95% CI, 40%-48%) for BRCA1 carriers, and 52% (95% CI, 46%-58%) for BRCA2 carriers. After adjusting for study and year of diagnosis, BRCA1 and BRCA2 mutation carriers showed a more favorable survival than noncarriers (for BRCA1: hazard ratio [HR], 0.78; 95% CI, 0.68-0.89; P < .001; and for BRCA2: HR, 0.61; 95% CI, 0.50-0.76; P < .001). These survival differences remained after additional adjustment for stage, grade, histology, and age at diagnosis (for BRCA1: HR, 0.73; 95% CI, 0.64-0.84; P < .001; and for BRCA2: HR, 0.49; 95% CI, 0.39-0.61; P < .001). The BRCA1 HR estimate was significantly different from the HR estimated in the adjusted model (P for heterogeneity = .003).
CONCLUSION: Among patients with invasive EOC, having a germline mutation in BRCA1 or BRCA2 was associated with improved 5-year overall survival. BRCA2 carriers had the best prognosis.
Authors: Panigrahy D, Edin ML, Lee CR, Huang S, Bielenberg DR, Butterfield CE, Barnés CM, Mammoto A, Mammoto T, Luria A, Benny O, Chaponis DM, Dudley AC, Greene ER, Vergilio JA, Pietramaggiori G, Scherer-Pietramaggiori SS, Short SM, Seth M, Lih FB, Tomer KB, Yang J, Schwendener RA, Hammock BD, Falck JR, Manthati VL, Ingber DE, Kaipainen A, D'Amore PA, Kieran MW, Zeldin DC
Journal: J Clin Invest. 2012 Jan 3;122(1):178-91. doi: 10.1172/JCI58128. Epub 2011 Dec 19
Epoxyeicosatrienoic acids (EETs) are small molecules produced by cytochrome P450 epoxygenases. They are lipid mediators that act as autocrine or paracrine factors to regulate inflammation and vascular tone. As a result, drugs that raise EET levels are in clinical trials for the treatment of hypertension and many other diseases. However, despite their pleiotropic effects on cells, little is known about the role of these epoxyeicosanoids in cancer. Here, using genetic and pharmacological manipulation of endogenous EET levels, we demonstrate that EETs are critical for primary tumor growth and metastasis in a variety of mouse models of cancer. Remarkably, we found that EETs stimulated extensive multiorgan metastasis and escape from tumor dormancy in several tumor models. This systemic metastasis was not caused by excessive primary tumor growth but depended on endothelium-derived EETs at the site of metastasis. Administration of synthetic EETs recapitulated these results, while EET antagonists suppressed tumor growth and metastasis, demonstrating in vivo that pharmacological modulation of EETs can affect cancer growth. Furthermore, inhibitors of soluble epoxide hydrolase (sEH), the enzyme that metabolizes EETs, elevated endogenous EET levels and promoted primary tumor growth and metastasis. Thus, our data indicate a central role for EETs in tumorigenesis, offering a mechanistic link between lipid signaling and cancer and emphasizing the critical importance of considering possible effects of EET-modulating drugs on cancer.
Authors: Goldin E, Zheng W, Motabar O, Southall N, Choi JH, Marugan J, Austin CP, Sidransky E
Journal: PLoS One. 2012;7(1):e29861. Epub 2012 Jan 17.
Gaucher disease (GD), the most common lysosomal storage disorder, results from the inherited deficiency of the lysosomal enzyme glucocerebrosidase (GCase). Previously, wildtype GCase was used for high throughput screening (HTS) of large collections of compounds to identify small molecule chaperones that could be developed as new therapies for GD. However, the compounds identified from HTS usually showed reduced potency later in confirmatory cell-based assays. An alternate strategy is to perform HTS on mutant enzyme to identify different lead compounds, including those enhancing mutant enzyme activities. We developed a new screening assay using enzyme extract prepared from the spleen of a patient with Gaucher disease with genotype N370S/N370S. In tissue extracts, GCase is in a more native physiological environment, and is present with the native activator saposin C and other potential cofactors. Using this assay, we screened a library of 250,000 compounds and identified novel modulators of mutant GCase including 14 new lead inhibitors and 30 lead activators. The activities of some of the primary hits were confirmed in subsequent cell-based assays using patient-derived fibroblasts. These results suggest that primary screening assays using enzyme extracted from tissues is an alternative approach to identify high quality, physiologically relevant lead compounds for drug development.
Authors: Doria-Rose NA, Louder MK, Yang Z, O'Dell S, Nason M, Schmidt SD, McKee K, Seaman MS, Bailer RT, Mascola JR
Journal: J Virol. 2012 Jan 18. [Epub ahead of print]
HIV-1 neutralizing monoclonal antibodies (mAbs) define key targets for vaccine development and are being considered for passive prevention of infection. We analyzed the interaction of mAbs to two independent epitopes on the viral envelope glycoprotein. Potently neutralizing mAbs to the CD4 binding site and V1V2 region displayed no in vitro cross-competition and additive, though not synergistic, neutralization activity. Predicted neutralization coverage of a combination of two mAbs reached 97% on a 208-isolate panel.
Authors: Tyagi M, Hashimoto K, Shoemaker BA, Wuchty S, Panchenko AR
Journal: EMBO Rep. 2012 Jan 20. doi: 10.1038/embor.2011.261. [Epub ahead of print]
Although the identification of protein interactions by high-throughput (HTP) methods progresses at a fast pace, 'interactome' data sets still suffer from high rates of false positives and low coverage. To map the human protein interactome, we describe a new framework that uses experimental evidence on structural complexes, the atomic details of binding interfaces and evolutionary conservation. The structurally inferred interaction network is highly modular and more functionally coherent compared with experimental interaction networks derived from multiple literature citations. Moreover, structurally inferred and high-confidence HTP networks complement each other well, allowing us to construct a merged network to generate testable hypotheses and provide valuable experimental leads.