Tethering telomeric double- and single-stranded DNA-binding proteins inhibits telomere elongation

Mammalian telomeres are composed of G-rich repetitive double-stranded (ds) DNA with a 3' single-stranded (ss) overhang and associated proteins that together maintain chromosome end stability. Complete replication of telomeric DNA requires de novo elongation of the ssDNA by the enzyme telomerase, with telomeric proteins playing a key role in regulating telomerase-mediated telomere replication. In regards to the protein component of mammalian telomeres, TRF1 and TRF2 bind to the dsDNA of telomeres, whereas POT1 binds to the ssDNA portion. These three proteins are linked through either direct interactions or by the proteins TIN2 and TPP1. To determine the biological consequence of connecting telomeric dsDNA to ssDNA through a multiprotein assembly, we compared the effect of expressing TRF1 and POT1 in trans versus in cis in the form of a fusion of these two proteins, on telomere length in telomerase-positive cells. When expressed in trans these two proteins induced extensive telomere elongation. Fusing TRF1 to POT1 abrogated this effect, inducing mild telomere shortening, and generated looped DNA structures, as assessed by electron microscopy, consistent with the protein forming a complex with dsDNA and ssDNA. We speculate that such a protein bridge between dsDNA and ssDNA may inhibit telomerase access, promoting telomere shortening.     

Anti-Remodeling Effects of Rapamycin in Experimental Heart Failure: Dose Response and Interaction with Angiotensin Receptor Blockade

While neurohumoral antagonists improve outcomes in heart failure (HF), cardiac remodeling and dysfunction progress and outcomes remain poor. Therapies superior or additive to standard HF therapy are needed. Pharmacologic mTOR inhibition by rapamycin attenuated adverse cardiac remodeling and dysfunction in experimental heart failure (HF). However, these studies used rapamycin doses that produced blood drug levels targeted for primary immunosuppression in human transplantation and therefore the immunosuppressive effects may limit clinical translation. Further, the relative or incremental effect of rapamycin combined with standard HF therapies targeting upstream regulators of cardiac remodeling (neurohumoral antagonists) has not been defined. Our objectives were to determine if anti-remodeling effects of rapamycin were preserved at lower doses and whether rapamycin effects were similar or additive to a standard HF therapy (angiotensin receptor blocker (losartan)). Experimental murine HF was produced by transverse aortic constriction (TAC). At three weeks post-TAC, male mice with established HF were treated with placebo, rapamycin at a dose producing immunosuppressive drug levels (target dose), low dose (50% target dose) rapamycin, losartan or rapamycin + losartan for six weeks. Cardiac structure and function (echocardiography, catheterization, pathology, hypertrophic and fibrotic gene expression profiles) were assessed. Downstream mTOR signaling pathways regulating protein synthesis (S6K1 and S6) and autophagy (LC3B-II) were characterized. TAC-HF mice displayed eccentric hypertrophy, systolic dysfunction and pulmonary congestion. These perturbations were attenuated to a similar degree by oral rapamycin doses achieving target (13.3±2.1 ng/dL) or low (6.7±2.5 ng/dL) blood levels. Rapamycin treatment decreased mTOR mediated regulators of protein synthesis and increased mTOR mediated regulators of autophagy. Losartan monotherapy did not attenuate remodeling, whereas Losartan added to rapamycin provided no incremental benefit over rapamycin alone. These data lend support to investigation of low dose rapamycin as a novel therapy in human HF.     

An Aberrant Transcription Factor Network Essential for Wnt Signaling and Stem Cell Maintenance in Glioblastoma

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Aspirin Prevents Apoptosis and NF-κB Activation Induced by H2O2 in HeLa Cells

The classical pathway of nuclear factor-kappa B (NF-κB) activation by several inducers mainly involves the phosphorylation of IκBα by a signalsome complex composed of IκBα kinases (IKKα and IKKβ). However, in some cell types hydrogen peroxide (H²O²) has been shown to activate an alternative pathway that does not involve the classical signalsome activation process. In this study, we demonstrate that H²O² induced NF-κB activation in HeLa cells through phosphorylation and degradation of IκB proteins as shown by immunblot analysis. Our studies reveal that a commonly used non-steroid anti-inflammatory drug, acetylsalicylic acid (aspirin) prevents H²O²-induced NF-κB activation in a dose-dependent manner through inhibition of phosphorylation and degradation of IκBα and IκBβ. Differential staining and DNA fragmentation analysis also show that aspirin preloading of HeLa cells also prevents H²O²-induced apoptosis in a dose-dependent manner with maximum efficiency at 10?mM concentration. Additionally, aspirin effectively prevents caspase-3 and caspase-9 (cysteinyl aspartate-specific proteases) activation by H²O². These results suggest that NF-κB activation is involved in H²O²-induced apoptosis and aspirin may inhibit both processes simultaneously.     

Genetic polymorphisms of estrogen receptor alpha and catechol-O-methyltransferase genes in Turkish patients with familial prostate carcinoma

OBJECTIVES:

Estrogen is one of the most crucial hormones participating in the proliferation and carcinogenesis of the prostate glands. Genetic polymorphisms in the estrogen metabolism pathway might be involved in the risk of prostate carcinoma development. We evaluated the association between genetic polymorphisms in estrogen receptor alpha (ESR1) and catechol-O-methyltransferase (COMT) genes and the risk of developing familial prostate carcinoma.

MATERIALS AND METHODS:

In this study, 34 cases with prostate carcinoma whose first-degree relatives had prostate carcinoma and 30 healthy age-matched male controls were enrolled. The genotypes of ESR1 and COMT genes were analyzed employing polymerase chain reaction-restriction fragment length polymorphism method. 34 cases with prostate carcinoma, whose first degree relatives had prostate carcinoma and 14 age-matched male controls were enrolled to analyze the genotype of these two genes.

RESULTS:

Among control patients, the ESR1 PvuII genotypes of C/C, C/T and T/T were observed in 37%, 26% and 37%, respectively, whereas the C/C, C/T and T/T genotypes were observed in 18%, 41% and 41% of case patients, respectively. Among controls, the ESR1 PvuII allele frequencies of C and T were equally observed, whereas the C and T allele frequencies were observed in 38% and 62% of patients, respectively. Among ESR1 PvuII genotypes there were not any significant difference in terms of genotype (P = 0.199) and allele (P = 0.181) frequencies. Among controls, the ESR1 XbaI genotypes of G/G, G/A and A/A were observed in 33%, 37% and 33%, respectively, whereas the G/G, G/A and A/A genotypes were observed in 12%, 47% and 41% of patients, respectively. Among controls, the ESR1 XbaI allele frequencies of A and G were observed equally, respectively, whereas the A and G frequencies were observed in 65% and 35% of patients, respectively. Among ESR1 Χ baI, there was not any significant difference in terms of genotype (P = 0.111) and allele (P = 0.093) frequencies. But the C/C genotype of the PvuII site and G/G genotype of the XbaI site in the ESR1 gene were associated significantly with the risk of developing prostate carcinoma. The G/G, G/A and A/A genotypes of the COMT gene were observed in 50%, 29% and 21% of control patients and in 53%, 21% and 26% of case patients, respectively. The A and G allele frequencies of the COMT gene were observed in 36.7%, 63.3% of control patients and in 36.8%, 63.2% of case patients, respectively. In COMT gene, there was not any significant difference in terms of genotype (P = 0.843) and allele (P = 0.991) frequencies. But the G/A genotype of the COMT gene had a weak tendency toward increased risk.

CONCLUSION:

Polymorphisms of ESR1 gene in the estrogen metabolism pathway were associated significantly with familial prostate carcinoma risk. Single nucleotide polymorphisms of low-penetrance genes are targets for understanding the genetic susceptibility of familial prostate carcinoma.     

Synthesis and antinociceptive-antimicrobial activities of some new amide derivatives of 3,5-di/-and 1,3,5-trimethylpyrazoles

Some N-(3,5-di-/1,3,5-trimethylpyrazole-4-yl)-4-substitutedbenzamide derivatives were prepared as possible antiociceptive-antimicrobial agents. New amide derivatives (3–12) were synthesized by reacting 4-amino-3,5-di and 1,3,5-trimethylpyrazoles with 4-substitutedbenzoyl chlorides. Hotplate and tail-immersion tests were used for the determination of the antinociceptive activity. Morphine, was used as a standard test drug. All compounds were administered at a dose of 100 mg/kg ip and some of them had significant antinociceptive activity in both tests. Compound 10 (N-(1,3,5-trimethylpyrazole-4-yl)-4-bromobenzamide), was the most active one in both tests among the compounds. The antinociceptive activity of the compounds 10, 11 (N-(1,3,5-trimethylpyrazole-4-yl)-4-chlorobenzamide), and 12 (N-(1,3,5-trimethylpyrazole-4-yl)-4-fluorobenzamide), started at 30 minutes and continued up to 150 minutes in the hotplate test. Also compounds were tested for their in vitro antimicrobial activity, but exhibited weak antibacterial activity.     

Systemically Circulating Viral and Tumor-Derived MicroRNAs in KSHV-Associated Malignancies

MicroRNAs (miRNAs) are stable, small non-coding RNAs that modulate many downstream target genes. Recently, circulating miRNAs have been detected in various body fluids and within exosomes, prompting their evaluation as candidate biomarkers of diseases, especially cancer. Kaposi''s sarcoma (KS) is the most common AIDS-associated cancer and remains prevalent despite Highly Active Anti-Retroviral Therapy (HAART). KS is caused by KS-associated herpesvirus (KSHV), a gamma herpesvirus also associated with Primary Effusion Lymphoma (PEL). We sought to determine the host and viral circulating miRNAs in plasma, pleural fluid or serum from patients with the KSHV-associated malignancies KS and PEL and from two mouse models of KS. Both KSHV-encoded miRNAs and host miRNAs, including members of the miR-17–92 cluster, were detectable within patient exosomes and circulating miRNA profiles from KSHV mouse models. Further characterization revealed a subset of miRNAs that seemed to be preferentially incorporated into exosomes. Gene ontology analysis of signature exosomal miRNA targets revealed several signaling pathways that are known to be important in KSHV pathogenesis. Functional analysis of endothelial cells exposed to patient-derived exosomes demonstrated enhanced cell migration and IL-6 secretion. This suggests that exosomes derived from KSHV-associated malignancies are functional and contain a distinct subset of miRNAs. These could represent candidate biomarkers of disease and may contribute to the paracrine phenotypes that are a characteristic of KS.     

Visual motion and the perception of surface material

Many critical perceptual judgments, from telling whether fruit is ripe to determining whether the ground is slippery, involve estimating the material properties of surfaces. Very little is known about how the brain recognizes materials, even though the problem is likely as important for survival as navigating or recognizing objects. Though previous research has focused nearly exclusively on the properties of static images, recent evidence suggests that motion may affect the appearance of surface material. However, what kind of information motion conveys and how this information may be used by the brain is still unknown. Here, we identify three motion cues that the brain could rely on to distinguish between matte and shiny surfaces. We show that these motion measurements can override static cues, leading to dramatic changes in perceived material depending on the image motion characteristics. A classifier algorithm based on these cues correctly predicts both successes and some striking failures of human material perception. Together these results reveal a previously unknown use for optic flow in the perception of surface material properties.