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CTCF is a zinc finger DNA-binding protein that regulates the epigenetic states of numerous target genes. Using allelic regulation of mouse insulin-like growth factor II (Igf2) as a model, we demonstrate that CTCF binds to the unmethylated maternal allele of the imprinting control region (ICR) in the Igf2/H19 imprinting domain and forms a long-range intrachromosomal loop to interact with the three clustered Igf2 promoters. Polycomb repressive complex 2 is recruited through the interaction of CTCF with Suz12, leading to allele-specific methylation at lysine 27 of histone H3 (H3-K27) and to suppression of the maternal Igf2 promoters. Targeted mutation or deletion of the maternal ICR abolishes this chromatin loop, decreases allelic H3-K27 methylation, and causes loss of Igf2 imprinting. RNA interference knockdown of Suz12 also leads to reactivation of the maternal Igf2 allele and biallelic Igf2 expression. CTCF and Suz12 are coprecipitated from nuclear extracts with antibodies specific for either protein, and they interact with each other in a two-hybrid system. These findings offer insight into general epigenetic mechanisms by which CTCF governs gene expression by orchestrating chromatin loop structures and by serving as a DNA-binding protein scaffold to recruit and bind polycomb repressive complexes. [ABSTRACT FROM AUTHOR]

Presents a study that designed a methylated oligonucleotide (MON1) complementary to a region encompassing insulin-like growth factor (IGF)2 promoter P4 in an attempt to induce DNA methylation at the locus and diminish IGF2 mRNA levels. Background on IGF2; Methodology; Results of the study.

In animal cells, mitochondria are the primary powerhouses and metabolic factories. They also contain genomes and can produce mitochondrial-specific nucleic acids and proteins. To maintain homeostasis of the entire cell, an intense cross-talk between mitochondria and the nucleus, mediated by encoded noncoding RNAs (ncRNAs), as well as proteins, is required. Long ncRNAs (lncRNAs) contain characteristic structures, and they are involved in the regulation of almost every stage of gene expression, as well as being implicated in a variety of disease states, such as cancer. In the coordinated signaling system, several lncRNAs, transcribed in the nucleus but residing in mitochondria, play a key role in regulating mitochondrial functions or dynamics. For example, RMRP, a component of the mitochondrial RNase MRP, is important for mitochondrial DNA replication and RNA processing, and the steroid receptor RNA activator, SRA, is a key modulator of hormone signaling and is present in both the nucleus and mitochondria. Some RNA-binding proteins maybe play a role in the lncRNAs transport system, such as HuR, GRSF1, SHARP, SLIRP, PPR, and PNPASE. Furthermore, a series of nuclear DNA-encoded lncRNAs were implicated in mitochondria-mediated apoptosis, mitochondrial bioenergetics and biosynthesis, and glutamine metabolism. The mitochondrial genome can also encode a set of lncRNAs, and they are divided into three categories: (1) lncND5, lncND6, and lncCyt b RNA; (2) chimeric mitochondrial DNA-encoded lncRNAs; and (3) putative mitochondrial DNA-encoded lncRNAs. It has been reported that the mitochondrial DNA-encoded lncRNAs appear to operate in the nucleus. The molecular mechanisms underlying trafficking of the mitochondrial DNA-encoded lncRNAs to the nucleus in mammals are only now beginning to emerge. In conclusion, both nuclear- and mitochondrial DNA-encoded lncRNAs mediate an intense intercompartmental cross-talk, which opens a rich field for investigation of the mechanism underlying the intercompartmental coordination and the maintenance of whole cell homeostasis. [ABSTRACT FROM AUTHOR]

Monoallelic expression of IGF2 is regulated by CCCTC binding factor (CTCF) binding to the imprinting control region (ICR) on the maternal allele, with subsequent formation of an intrachromosomal loop to the promoter region. The N-terminal domain of CTCF interacts with SUZ12, part of the polycomb repressive complex-2 (PRC2), to silence the maternal allele. We synthesized decoy CTCF proteins, fusing the CTCF deoxyribonucleic acid-binding zinc finger domain to CpG methyltransferase Sss1 or to enhanced green fluorescent protein. In normal human fibroblasts and breast cancer MCF7 cell lines, the CTCF decoy proteins bound to the unmethylated ICR and to the IGF2 promoter region but did not interact with SUZ12. EZH2, another part of PRC2, was unable to methylate histone H3-K27 in the IGF2 promoter region, resulting in reactivation of the imprinted allele. The intrachromosomal loop between the maternal ICR and the IGF2 promoters was not observed when IGF2 imprinting was lost. CTCF epigenetically governs allelic gene expression of IGF2 by orchestrating chromatin loop structures involving PRC2. [ABSTRACT FROM AUTHOR]

To find the origin of the T 2 difference between the Bloch–Grüneisen law and the Debye law, a resistivity statistical model for ideal metals is presented. In the model, the system is regarded as a phonon system in which all phonons have the same momentum value, i.e., the mean momentum. The principal point of the simplified model is that the electrons located at the Fermi surface are scattered by these mean-momentum phonons. It is found that the electrical resistivity of an ideal metal is directly proportional to the phonon concentration and the square of the phonon mean momentum, which first related the electrical resistivity to the phonon parameters. The theoretical results from the model are consistent with experimental observations that the electrical resistivity is directly proportional to temperature T at high temperatures, and to T 5 at very low temperatures, naturally, this is consistent with the Bloch–Grüneisen law. It is found by theoretical analyses that the heat capacity of a solid at very low temperatures is only proportional to the phonon concentration. Therefore, the contribution of the square of phonon mean momentum to the electrical resistivity brings about the T 2 difference between the Bloch–Grüneisen law and the Debye law. PACS Nos.: 72.10.Di, 65.40.Ba [ABSTRACT FROM AUTHOR]

Background aims. Acute liver failure (ALF), a life-threatening disease characterized by the sudden loss of hepatic function, can occur after an accidental or intentional acetaminophen overdose. Methods. With the use of an ALF mouse model, we examined both the preventive and therapeutic potential of intravenously administered human umbilical cord-derived mesenchymal stromal cells (hUCMSCs). Primary hUCMSCs were purified from freshly collected full-term umbilical cords and intravenously transplanted into BALB/c mice either before and after ALF induced by acetaminophen intoxication. We found that hUCMSCs significantly improved survival rates and relative liver weight of mice in both pre-ALF and post-ALF animals. Correspondingly, serum levels of markers that reflect hepatic injury (ie, aspartate aminotransferase, alanine aminotransferase and total bilirubin) were significantly attenuated in the group receiving hUCMSC therapy Results Mechanistically, we found that the protective potential of intravenously administered hUCMSCs was mediated by paracrine pathways that involved antioxidants (glutathione, superoxide dismutase), the reduction of inflammatory agents (tumor necrosis factor-a, mterleukin-6) and elevated serum levels of hepatocyte growth factor. Conclusions. Through these paracrine effects, intravenously administered hUCMSCs reduced hepatic necrosis/apoptosis and enhanced liver regeneration Thus our data demonstrate that intravenously administered hUCMSCs may be useful in the prevention or treatment of acetaminophen- induced ALF. [ABSTRACT FROM AUTHOR]

Knqlotl is a long noncoding ribonucleic acid RNA; IncRNA) that participates in the regulation of genes within the Kcnql imprinting domain. Using a novel RNA-guided chromatin conformation capture method, we demonstrate that the 5' region of Kcnqlotl RNA orchestrates a long-range intrachromosomal loop between KvDMR1 and the Kcnql promoter that is required for maintenance of imprinting. PRC2 (polycomb repressive complex 2), which participates in the allelic repression of Kcnq 1, is also recruited by Kcnq Ioti RNA via EZH2. Targeted suppression of Kcnqlotl IncRNA prevents the creation of this long-range intrachromosomal loop and causes loss of Kcnq 1 imprinting. These observations delineate a novel mechanism by which an IncRNA directly builds an intrachromosomal interaction complex to establish allele-specific transcriptional gene silencing over a large chromosomal domain. [ABSTRACT FROM AUTHOR]

Notch signaling pathway plays an important role in tumorigenesis by maintaining the activity of self-renewal of cancer stem cells, and therefore, it is hypothesized that interference of Notch signaling may inhibit tumor formation and progression. H101 is a recombinant oncolytic adenovirus that is cytolytic in cells lacking intact p53, but it is unable to eradicate caner stem cells. In this study, we tested a new strategy of tumor gene therapy by combining a Notch1-siRNA with H101 oncolytic adenovirus. In HeLa-S3 tumor cells, the combined therapy blocked the Notch pathway and induced apoptosis in tumors that are p53-inactive. In nude mice bearing xenograft tumors derived from HeLa-S3 cells, the combination of H101/Notch1-siRNA therapies inhibited tumor growth. Moreover, Notch1-siRNA increased Hexon gene expression at both the transcriptional and the translational levels, and promoted H101 replication in tumors, thereby enhancing the oncolytic activity of H101. These data demonstrate the feasibility to combine H101 p53-targted oncolysis and anti-Notch siRNA activities as a novel anti-cancer therapy. [ABSTRACT FROM AUTHOR]

The article presents information on a study which identified the Friend leukemia virus integration 1 gene (FLI1) as a clinically significant target for miR-145. A brief information on microRNA is offered. The role of FLI1 in t(11;22)(q24:q12) reciprocal chromosomal translocation in Ewing sarcoma is explained. It discusses the reversed expression of FLI1 with miR-145 in colon tumor tissues.

Targeting tumor-specific gene abnormalities has become an attractive approach in developing therapeutics to treat cancer. Overexpression of Bcl2 and mutations of p53 represent two of the most common molecular defects in tumors. In the nucleus, p53 induces cell cycle arrest, while it interacts with Bcl2 outside of the nucleus to regulate signal pathways involved in apoptosis. To potentiate antitumor activity, we tested a “double target” approach to antitumor therapy by combining H101, a recombinant oncolytic adenovirus that targets the inactive p53 in tumors, with a small interfering RNA (siBCL2) that targets Bcl2. In cell culture, the combined treatment significantly enhanced apoptosis and cytotoxicity as compared with treatment with either H101 or siBCL2 alone. In animals carrying tumor xenographs, combined H101 and siBCL2 treatment significantly inhibited tumor growth and prolonged survival. At the end of the study, all animals in the combined therapy group survived and two of the five animals showed complete eradication of their tumors. Interestingly, siBCL2 treatment increased H101 viral replication in both treated cells and tumor tissues. Simultaneously targeting two tumor-specific gene abnormalities using an oncolytic adenovirus and siRNA potentiates total antitumor activity.Molecular Therapy (2008) 17 1, 57–64 doi:10.1038/mt.2008.236 [ABSTRACT FROM AUTHOR]

Loss of genomic imprinting of insulin-like growth factor II (IGF2) is a hallmark of many human neoplasms. We attempted to correct this aberrant epigenotype by transferring nuclei from human tumor cells that showed loss of IGF2 imprinting into enucleated mouse and human fibroblasts that had maintained normal IGF2 imprinting. After nuclear transfer, the abnormal biallelic expression of IGF2 in tumor nuclei transiently converted to normal monoallelic imprinted expression in the reconstructed diploid cells. In tetraploid hybrid cells, however, normal IGF2 imprinting was permanently restored in the tumor genome. Inhibition of the synthesis of putative trans imprinting factors with cycloheximide led to loss of IGF2 imprinting in normal cultured fibroblasts, suggesting that normal cells produce proteins that act in trans to induce or maintain genomic imprinting. These data demonstrate that an abnormal tumor epigenotype can be corrected by in vitro reprogramming, and suggest that loss of imprinting is associated with the loss of activity of non-CTCF trans imprinting factor(s) that are either inactivated or mutated in tumors. [ABSTRACT FROM AUTHOR]