Functional Role of Dead-Box P68 RNA Helicase in Gene Expression

How tumor cells migrate and metastasize from primary sites requires four major steps: invasion, intravasation, extravasation and proliferation from micrometastases to malignant tumor. The initiation of tumor cell invasion requires Epithelial-Mesenchymal Transition (EMT), by which tumor cells lose cell-cell interactions and gain the ability of migration. The gene expression profile during the EMT process has been extensively investigated to study the initiation of EMT. In our studies, we indicated that tyrosine phosphorylation of human p68 RNA helicase positively associated with the malignant status of tumor tissue or cells. Studying of this relationship revealed that p68 RNA helicase played a critical role in EMT progression by repression of E-cadherin as an epithelial marker and upregulation of Vimentin as a mesenchymal marker. Insight into the mechanism of how p68 RNA helicase represses E-cadherin expression indicated that p68 RNA helicase initiated EMT by transcriptional upregulation of Snail. Human p68 RNA helicase has been documented as an RNA-dependent ATPase. The protein is an essential factor in the pre-mRNA splicing procedure. Some examples show that p68 RNA helicase functions as a transcriptional coactivator in ATPase dependent or independent manner. Here we indicated that p68 RNA helicase unwound protein complexes to modulate protein-protein interactions by using protein-dependent ATPase activity. The phosphorylated p68 RNA helicase displaced HDAC1 from the chromatin remodeling MBD3:Mi2/NuRD complex at the Snail promoter. Thus, our data demonstrated an example of protein-dependent ATPase which modulates protein-protein interactions within the chromatin remodeling machine

TNF-related weak inducer of apoptosis as a regulator of β-oxidation and differentiation in murine adipocytes

https://openworks.mdanderson.org/sumexp22/1145/thumbnail.jp

lncRNA-dependent mechanisms of androgen-receptor-regulated gene activation programs.

Although recent studies have indicated roles of long non-coding RNAs (lncRNAs) in physiological aspects of cell-type determination and tissue homeostasis, their potential involvement in regulated gene transcription programs remains rather poorly understood. The androgen receptor regulates a large repertoire of genes central to the identity and behaviour of prostate cancer cells, and functions in a ligand-independent fashion in many prostate cancers when they become hormone refractory after initial androgen deprivation therapy. Here we report that two lncRNAs highly overexpressed in aggressive prostate cancer, PRNCR1 (also known as PCAT8) and PCGEM1, bind successively to the androgen receptor and strongly enhance both ligand-dependent and ligand-independent androgen-receptor-mediated gene activation programs and proliferation in prostate cancer cells. Binding of PRNCR1 to the carboxy-terminally acetylated androgen receptor on enhancers and its association with DOT1L appear to be required for recruitment of the second lncRNA, PCGEM1, to the androgen receptor amino terminus that is methylated by DOT1L. Unexpectedly, recognition of specific protein marks by PCGEM1-recruited pygopus 2 PHD domain enhances selective looping of androgen-receptor-bound enhancers to target gene promoters in these cells. In 'resistant' prostate cancer cells, these overexpressed lncRNAs can interact with, and are required for, the robust activation of both truncated and full-length androgen receptor, causing ligand-independent activation of the androgen receptor transcriptional program and cell proliferation. Conditionally expressed short hairpin RNA targeting these lncRNAs in castration-resistant prostate cancer cell lines strongly suppressed tumour xenograft growth in vivo. Together, these results indicate that these overexpressed lncRNAs can potentially serve as a required component of castration-resistance in prostatic tumours

Mechanism of efficient double-strand break repair by a long non-coding RNA.

Mechanistic studies in DNA repair have focused on roles of multi-protein DNA complexes, so how long non-coding RNAs (lncRNAs) regulate DNA repair is less well understood. Yet, lncRNA LINP1 is over-expressed in multiple cancers and confers resistance to ionizing radiation and chemotherapeutic drugs. Here, we unveil structural and mechanistic insights into LINP1's ability to facilitate non-homologous end joining (NHEJ). We characterized LINP1 structure and flexibility and analyzed interactions with the NHEJ factor Ku70/Ku80 (Ku) and Ku complexes that direct NHEJ. LINP1 self-assembles into phase-separated condensates via RNA-RNA interactions that reorganize to form filamentous Ku-containing aggregates. Structured motifs in LINP1 bind Ku, promoting Ku multimerization and stabilization of the initial synaptic event for NHEJ. Significantly, LINP1 acts as an effective proxy for PAXX. Collective results reveal how lncRNA effectively replaces a DNA repair protein for efficient NHEJ with implications for development of resistance to cancer therapy

Electrochemistry of Sc3N@C-78 and Sc3N@C-80 (I-h): On achieving reversible redox waves of the trimetal nitride endohedral fullerenes

Electrochemical behavior Of Sc3N@C-78 Solution was investigated for the first time by cyclic voltammetry (CV) as well as differential pulse voltammetry (DPV). Reversible redox features Of Sc3N@C-78 were obtained in contrast to that of Dy3N@C-78, for which the corresponding redox waves were very recently found to be irreversible. Toluene/MeCN and four other solvents have been identified, wherewith reversible redox waves can also be observed for Sc3N@C-80 (I-n) at a normal potential scan rate, whereas o-dichlorobenzene (o-DCB) was found to give only irreversible redox behavior as concluded by other researchers. The redox properties Of Sc3N@C78 and Sc3N@C-80 (I-n) are comparatively discussed on the basis of their different electronic structures and interactions with the solvent molecules. Additionally, electrochemical energy gaps of both Sc3N@C78 and Sc3N@C-80 (I-n) were obtained. (c) 2007 Elsevier B.V. All rights reserved

ATPase/Helicase Activities of p68 RNA Helicase Are Required for Pre-mRNA Splicing but Not for Assembly of the Spliceosome

We have previously demonstrated that p68 RNA helicase, as an essential human splicing factor, acts at the U1 snRNA and 5′ splice site (5′ss) duplex in the pre-mRNA splicing process. To further analyze the function of p68 in the spliceosome, we generated two p68 mutants (motif V, RGLD to LGLD, and motif VI, HRIGR to HLIGR). ATPase and RNA unwinding assays demonstrated that the mutations abolished the RNA-dependent ATPase activity and RNA unwinding activity. The function of p68 in the spliceosome was abolished by the mutations, and the mutations also inhibited the dissociation of U1 from the 5′ss, while the mutants still interacted with the U1-5′ss duplex. Interestingly, the nonactive p68 mutants did not prevent the transition from prespliceosome to the spliceosome. The data suggested that p68 RNA helicase might actively unwind the U1-5′ss duplex. The protein might also play a role in the U4.U6/U5 addition, which did not require the ATPase and RNA unwinding activities of p68. In addition, we present evidence here to demonstrate the functional role of p68 RNA helicase in the pre-mRNA splicing process in vivo. Our experiments also showed that p68 interacted with unspliced but not spliced mRNA in vivo

Fullerene-Induced Increase of Glycosyl Residue on Living Plant Cell Wall

In this work, we have investigated the change of cell wall for the tobacco plant cell (Nicotiana tobacurn L. cv. Bright Yellow) under the repression of water-soluble carboxyfullerenes (C-70(C(COOH)(2))(2-4)). The adsorption of C-70(C(COOH)(2))(2-4) on cell wall led to the disruption of cell wall and membrane, and consequently, cell growth inhibition. Results from atomic force microscopy (AFM) force measurement and confocal imaging revealed an increase of the glycosyl residue on the cell wall of carboxyfullerene-treated cells, with a time- and dose-dependent manner, and accompanied by the elevated reactive oxygen species (ROS). Moreover, the stimulation-sensitive alteration of glycosyl residue and ROS was demonstrated, which suggested a possible protection strategy for the plant cells under fullerene repression. This study provides the first direct evidence on the change of plant cell wall composition under the repression of fullerene and is the first successful application of AFM ligand-receptor binding force measurement to the living plant cell. The new information present here would help to a better understanding and assessment of the biological effect of fullerenes on plant

Electrochemistry of Sc3N@C-78 embedded in didodecyldimethylammonium bromide films in aqueous solution

The electrochemical behavior of trimetallic nitride clusterfullerene (Sc3N@C-78) embedded in films of the cationic surfactant didodecyldimethylammonium bromide (DDAB) on glassy carbon (GC) electrodes in aqueous solution was investigated. Four pairs of reversible redox peaks were observed in the potential range between +0.6 and -0.9 V vs. SCE. Different to the electrochemistry of pristine Sc3N@C-78 in organic solution, the first reduction is a one-electron rather than simultaneous two-electron process because of the strong binding between DDA(+) and the monoanion of Sc3N@C-78. The generated radial monoanion, dianion and trianion of Sc3N@C-78 are stable during continuous potential cycling, while some chemical reactions take place when the third anion is further reduced in the films. The cyclic voltammograms of Sc3N@C-78/DDAB films checked at different temperatures pointed to strong temperature dependence. The electrochemical processes were also measured in different electrolytes, which showed pronounced anionic dependence and no cathodic dependence on either the cation or anions present. A possible electron-transfer mechanism of a Sc3N@C-78/DDAB film was presented