Study of Protein Arginine Methyltransferase 6 in Medulloblastoma

https://openworks.mdanderson.org/sumexp21/1180/thumbnail.jp

Cytotoxic Potential of MIthramycin against DIPG cell lines

https://openworks.mdanderson.org/sumexp22/1092/thumbnail.jp

Noise Propagation in Two-Step Series MAPK Cascade

Series MAPK enzymatic cascades, ubiquitously found in signaling networks, act as signal amplifiers and play a key role in processing information during signal transduction in cells. In activated cascades, cell-to-cell variability or noise is bound to occur and thereby strongly affects the cellular response. Commonly used linearization method (LM) applied to Langevin type stochastic model of the MAPK cascade fails to accurately predict intrinsic noise propagation in the cascade. We prove this by using extensive stochastic simulations for various ranges of biochemical parameters. This failure is due to the fact that the LM ignores the nonlinear effects on the noise. However, LM provides a good estimate of the extrinsic noise propagation. We show that the correct estimate of intrinsic noise propagation in signaling networks that contain at least one enzymatic step can be obtained only through stochastic simulations. Noise propagation in the cascade depends on the underlying biochemical parameters which are often unavailable. Based on a combination of global sensitivity analysis (GSA) and stochastic simulations, we developed a systematic methodology to characterize noise propagation in the cascade. GSA predicts that noise propagation in MAPK cascade is sensitive to the total number of upstream enzyme molecules and the total number of molecules of the two substrates involved in the cascade. We argue that the general systematic approach proposed and demonstrated on MAPK cascade must accompany noise propagation studies in biological networks

REST-Dependent Downregulation of Von Hippel-Lindau Tumor Suppressor Promotes Autophagy in SHH-Medulloblastoma

The RE1 silencing transcription factor (REST) is a driver of sonic hedgehog (SHH) medulloblastoma genesis. Our previous studies showed that REST enhances cell proliferation, metastasis and vascular growth and blocks neuronal differentiation to drive progression of SHH medulloblastoma tumors. Here, we demonstrate that REST promotes autophagy, a pathway that is found to be significantly enriched in human medulloblastoma tumors relative to normal cerebella. In SHH medulloblastoma tumor xenografts, REST elevation is strongly correlated with increased expression of the hypoxia-inducible factor 1-alpha (HIF1α)-a positive regulator of autophagy, and with reduced expression of the von Hippel-Lindau (VHL) tumor suppressor protein - a component of an E3 ligase complex that ubiquitinates HIF1α. Human SHH-medulloblastoma tumors with higher REST expression exhibit nuclear localization of HIF1α, in contrast to its cytoplasmic localization in low-REST tumors. In vitro, REST knockdown promotes an increase in VHL levels and a decrease in cytoplasmic HIF1α protein levels, and autophagy flux. In contrast, REST elevation causes a decline in VHL levels, as well as its interaction with HIF1α, resulting in a reduction in HIF1α ubiquitination and an increase in autophagy flux. These data suggest that REST elevation promotes autophagy in SHH medulloblastoma cells by modulating HIF1α ubiquitination and stability in a VHL-dependent manner. Thus, our study is one of the first to connect VHL to REST-dependent control of autophagy in a subset of medulloblastomas

Mitochondrial DNA marker reveals shallow genetic structuring in Priacanthus hamrur (Forsskål, 1775) along the Indian coast

Priacanthus hamrur (Forsskål, 1775), a marine perch belonging to the family Priacanthidae commonly known as “bulls eye” has started emerging as an important fishery resource in the trawl landings along both the west and east coasts of India. In the present study, genetic stock structure of P. hamrur inhabiting Indian coastal waters was ascertained with mitochondrial DNA sequences from the cytochrome b (cyt-b) gene using samples of the species collected in two samplings from five different geographical locations, viz. Chennai and Visakhapatnam (east coast) and Cochin, Mumbai and Veraval (West coast). Partial sequence of cyt-b gene of P. hamrur from 5 representative regions along the coastal zones was amplified by PCR. The cyt- b marker revealed high haplotype diversity coupled with very low nucleotide diversity within each population, as well as low genetic distance, high gene flow, and high mitochondrial DNA similarity among all five populations. Phylogenetic trees and pairwise analyses demonstrated a very small divergence (0.43-0.64%) between the populations, suggesting the lack of population subdivisions. The overall lack of genetic subdivision among samples was also detected by the analysis of molecular variance, and pairwise FST values. Furthermore, the results of this study revealed a pattern of high nucleotide homology among the adjacent populations, and a small number of nucleotide changes among disjunct populations, leading us to conclude that there is a genetic connectivity among the populations of P.hamrur inhabiting the coastal waters of India

Plant growth-promoting activities of Streptomyces spp. in sorghum and rice

Five strains of Streptomyces (CAI-24, CAI-121, CAI-127, KAI-32 and KAI-90) were earlier reported by us as biological control agents against Fusarium wilt of chickpea caused by Fusarium oxysporum f. sp. ciceri (FOC). In the present study, the Streptomyces were characterized for enzymatic activities, physiological traits and further evaluated in greenhouse and field for their plant growth promotion (PGP) of sorghum and rice. All the Streptomyces produced lipase, β-1-3-glucanase and chitinase (except CAI-121 and CAI-127), grew in NaCl concentrations of up to 6%, at pH values between 5 and 13 and temperatures between 20 and 40°C and were highly sensitive to Thiram, Benlate, Captan, Benomyl and Radonil at field application level. When the Streptomyces were evaluated in the greenhouse on sorghum all the isolates significantly enhanced all the agronomic traits over the control. In the field, on rice, the Streptomyces significantly enhanced stover yield (up to 25%; except CAI-24), grain yield (up to 10%), total dry matter (up to 18%; except CAI-24) and root length, volume and dry weight (up to 15%, 36% and 55%, respectively, except CAI-24) over the control. In the rhizosphere soil, the Streptomyces significantly enhanced microbial biomass carbon (except CAI-24), nitrogen, dehydrogenase (except CAI-24), total N, available P and organic carbon (up to 41%, 52%, 75%, 122%, 53% and 13%, respectively) over the control. This study demonstrates that the selected Streptomyces which were antagonistic to FOC also have PGP properties

Plant-derived tetranortriterpenoid, methyl angolensate activates apoptosis and prevents ehrlich ascites carcinoma induced tumorigenesis in mice

Background: Cancer is a leading health problem throughout the world. For decades, natural plant products have been playing promising roles as anticancer agents. Objective: The present study aims to investigate the chemotherapeutic potential of Methyl Angolensate (MA), purified from Soymida febrifuga in mice bearing carcinoma and examines the molecular basis for its anticancer actions. Study Design: The inhibitory effects of MA treatment on the survival of mice bearing Carcinoma and adverse side effects of MA treatment in mice were analyzed. Methods: Tumor volume, life span, histopathology, Immunohistochemical (IHC) analysis, estimation of liver enzyme, alkaline phosphatase and metabolites, creatinine and urea. Results: Oral administration of MA in mice with Ehrlich Ascites Carcinoma showed significant inhibition of tumor growth compared to untreated mice. We observed a significant increase in the life span (∼4-fold) of tumor bearing animals following treatment with MA. MA affected tumor cell proliferation by activating intrinsic pathway of apoptosis without imparting any side effect on normal cells. MA treatment in mice showed no major side effects. Conclusion: MA treatment showed significant inhibition of tumor growth by inducing apoptosis as well increased life span of mice, with no adverse side effects to normal cells. Altogether, the present in vivo study provides new insights of MA serving as a cancer chemotherapeutic agent

Delineating the Mechanism of Fragility at BCL6 Breakpoint Region Associated With Translocations in Diffuse Large B Cell Lymphoma

BCL6 translocation is one of the most common chromosomal translocations in cancer and results in its enhanced expression in germinal center B cells. It involves the fusion of BCL6 with any of its twenty-six Ig and non-Ig translocation partners associated with diffuse large B cell lymphoma (DLBCL). Despite being discovered long back, the mechanism of BCL6 fragility is largely unknown. Analysis of the translocation breakpoints in 5\u27 UTR of BCL6 reveals the clustering of most of the breakpoints around a region termed Cluster II. In silico analysis of the breakpoint cluster sequence identified sequence motifs that could potentially fold into non-B DNA. Results revealed that the Cluster II sequence folded into overlapping hairpin structures and identified sequences that undergo base pairing at the stem region. Further, the formation of cruciform DNA blocked DNA replication. The sodium bisulfite modification assay revealed the single-strandedness of the region corresponding to hairpin DNA in both strands of the genome. Further, we report the formation of intramolecular parallel G4 and triplex DNA, at Cluster II. Taken together, our studies reveal that multiple non-canonical DNA structures exist at the BCL6 cluster II breakpoint region and contribute to the fragility leading to BCL6 translocation in DLBCL patients