SIRT6 links histone H3 lysine 9 deacetylation to NF-kappaB-dependent gene expression and organismal life span.

Members of the sirtuin (SIRT) family of NAD-dependent deacetylases promote longevity in multiple organisms. Deficiency of mammalian SIRT6 leads to shortened life span and an aging-like phenotype in mice, but the underlying molecular mechanisms are unclear. Here we show that SIRT6 functions at chromatin to attenuate NF-kappaB signaling. SIRT6 interacts with the NF-kappaB RELA subunit and deacetylates histone H3 lysine 9 (H3K9) at NF-kappaB target gene promoters. In SIRT6-deficient cells, hyperacetylation of H3K9 at these target promoters is associated with increased RELA promoter occupancy and enhanced NF-kappaB-dependent modulation of gene expression, apoptosis, and cellular senescence. Computational genomics analyses revealed increased activity of NF-kappaB-driven gene expression programs in multiple Sirt6-deficient tissues in vivo. Moreover, haploinsufficiency of RelA rescues the early lethality and degenerative syndrome of Sirt6-deficient mice. We propose that SIRT6 attenuates NF-kappaB signaling via H3K9 deacetylation at chromatin, and hyperactive NF-kappaB signaling may contribute to premature and normal aging.

Liver Fibrosis in the Natural Course of Chronic Hepatitis B Viral Infection: A Systematic Review with Meta-Analysis.

BACKGROUND: Quantitative data are limited on the natural course of liver fibrosis in patients with chronic HBV infection (CHB). AIMS: To estimate the prevalence of fibrosis status including non-fibrosis, significant fibrosis, advanced fibrosis, and cirrhosis throughout the natural course of CHB. METHODS: We searched Cochrane library, EMBASE, PubMed, SCOPUS, Web of Science, and ScienceDirect from January 1993 to November 2019 for studies with histologic data on liver fibrosis in CHB natural course. CHB course was defined based on current criteria for identifying infection phases as recommended by international clinical practice guidelines, including the HBeAg-positive immune-tolerant, HBeAg-positive immune-active, HBeAg-negative immune-inactive, HBeAg-negative immune-reactive, and HBsAg-negative phases. Pooled prevalence rate of fibrosis status at each phase was obtained from random-effect meta-analyses. RESULTS: Thirty-three studies with 9,377 adult participants (23.8-49.0 age years; 45.5-88.6% males) were eligible and finally included. The estimated prevalence of non-fibrosis, significant fibrosis, advanced fibrosis, and cirrhosis was, for HBeAg-positive immune-tolerant phase: 31.2% (95%CI 15.6-46.7), 16.9% (95%CI 7.8-26.1), 5.4% (95%CI 0.0-11.2), and 0.0% (95%CI 0.0-1.5); HBeAg-positive immune-active phase: 6.9% (95%CI 3.6-10.2), 50.6% (95%CI 39.2-61.9), 32.1% (95%CI 24.2-40.0), and 12.8% (95%CI 8.6-17.0); HBeAg-negative immune-inactive phase: 32.4% (95%CI 0.0-100.0), 24.8% (95%CI 4.5-45.1), 3.0% (95%CI 0.0-8.3), and 0.0% (95%CI 0.0-1.0); and HBeAg-negative immune-reactive phase: 6.3% (95%CI 3.5-9.2), 50.3% (95%CI 38.9-61.7), 30.3% (95%CI 20.9-39.6), and 10.0% (95%CI 6.6-13.5), respectively. There was only one study for HBsAg-negative phase, thus not allowing further meta-analyses. CONCLUSIONS: Fibrosis risk persists through CHB natural course. These data can support risk estimation in clinical practice and provide reference for noninvasive investigation.

Insecticidal Triterpenes in Meliaceae: Plant Species, Molecules, and Activities: Part II (Cipadessa, Melia).

Plant-originated triterpenes are important insecticidal molecules. Research on the insecticidal activity of molecules from Meliaceae plants has always been a hotspot due to the molecules from this family showing a variety of insecticidal activities with diverse mechanisms of action. In this paper, we discussed 116 triterpenoid molecules with insecticidal activity from 22 plant species of five genera (Cipadessa, Entandrophragma, Guarea, Khaya, and Melia) in Meliaceae. In these genera, the insecticidal activities of plants from Entandrophragma and Melia have attracted substantial research attention in recent years. Specifically, the insecticidal activities of plants from Melia have been systemically studied for several decades. In total, the 116 insecticidal chemicals consisted of 34 ring-intact limonoids, 31 ring-seco limonoids, 48 rearranged limonoids, and 3 tetracyclic triterpenes. Furthermore, the 34 ring-intact limonoids included 29 trichilin-class chemicals, 3 azadirone-class chemicals, and 1 cedrelone-class and 1 havanensin-class limonoid. The 31 ring-seco limonoids consisted of 16 C-seco group chemicals, 8 B,D-seco group chemicals, 4 A,B-seco group chemicals, and 3 D-seco group chemicals. Furthermore, among the 48 rearranged limonoids, 46 were 2,30-linkage group chemicals and 2 were 10,11-linkage group chemicals. Specifically, the 46 chemicals belonging to the 2,30-linkage group could be subdivided into 24 mexicanolide-class chemicals and 22 phragmalin-class chemicals. Additionally, the three tetracyclic triterpenes were three protolimonoids. To sum up, 80 chemicals isolated from 19 plant species exhibited antifeedant activity toward 14 insect species; 18 chemicals isolated from 17 plant species exhibited poisonous activity toward 10 insect species; 16 chemicals isolated from 11 plant species possessed growth-regulatory activity toward 8 insect species. In particular, toosendanin was the most effective antifeedant and insect growth-regulatory agent. The antifeedant activity of toosendanin was significant. Owing to its high effect, toosendanin has been commercially applied. Three other molecules, 1,3-dicinnamoyl-11-hydroxymeliacarpin, 1-cinnamoyl-3-methacryl-11-hydroxymeliacarpin, and 1-cinnamoyl-3-acetyl-11-hydroxymeliacarpin, isolated from Meliaazedarach, exhibited a highly poisonous effect on Spodoptera littoralis; thus, they deserve further attention.

Insecticidal Triterpenes in Meliaceae: Plant Species, Molecules and Activities: Part â (Aphanamixis-Chukrasia).

Plant-originated triterpenes are important insecticidal molecules. The research on insecticidal activity of molecules from Meliaceae plants has always received attention due to the molecules from this family showing a variety of insecticidal activities with diverse mechanisms of action. In this paper, we discuss 102 triterpenoid molecules with insecticidal activity of plants of eight genera (Aglaia, Aphanamixis, Azadirachta, Cabralea, Carapa, Cedrela, Chisocheton, and Chukrasia) in Meliaceae. In total, 19 insecticidal plant species are presented. Among these species, Azadirachta indica A. Juss is the most well-known insecticidal plant and azadirachtin is the active molecule most widely recognized and highly effective botanical insecticide. However, it is noteworthy that six species from Cedrela were reported to show insecticidal activity and deserve future study. In this paper, a total of 102 insecticidal molecules are summarized, including 96 nortriterpenes, 4 tetracyclic triterpenes, and 2 pentacyclic triterpenes. Results showed antifeedant activity, growth inhibition activity, poisonous activity, or other activities. Among them, 43 molecules from 15 plant species showed antifeedant activity against 16 insect species, 49 molecules from 14 plant species exhibited poisonous activity on 10 insect species, and 19 molecules from 11 plant species possessed growth regulatory activity on 12 insect species. Among these molecules, azadirachtins were found to be the most successful botanical insecticides. Still, other molecules possessed more than one type of obvious activity, including 7-deacetylgedunin, salannin, gedunin, azadirone, salannol, azadiradione, and methyl angolensate. Most of these molecules are only in the primary stage of study activity; their mechanism of action and structure-activity relationship warrant further study.

In Vitro Evaluation of the Drug Interaction Potential of Doravirine.

Doravirine is a novel nonnucleoside reverse transcriptase inhibitor for the treatment of human immunodeficiency virus type 1 infection. In vitro studies were conducted to assess the potential for drug interactions with doravirine via major drug-metabolizing enzymes and transporters. Kinetic studies confirmed that cytochrome P450 3A (CYP3A) plays a major role in the metabolism of doravirine, with ∼20-fold-higher catalytic efficiency for CYP3A4 versus CYP3A5. Doravirine was not a substrate of breast cancer resistance protein (BCRP) and likely not a substrate of organic anion transporting polypeptide 1B1 (OATP1B1) or OATP1B3. Doravirine was not a reversible inhibitor of major CYP enzymes (CYP1A2, -2B6, -2C8, -2C9, -2C19, -2D6, and -3A4) or of UGT1A1, nor was it a time-dependent inhibitor of CYP3A4. No induction of CYP1A2 or -2B6 was observed in cultured human hepatocytes; small increases in CYP3A4 mRNA (≤20%) were reported at doravirine concentrations of ≥10 µM but with no corresponding increase in enzyme activity. In vitro transport studies indicated a low potential for interactions with substrates of BCRP, P-glycoprotein, OATP1B1 and OATP1B3, the bile salt extrusion pump (BSEP), organic anion transporter 1 (OAT1) and OAT3, organic cation transporter 2 (OCT2), and multidrug and toxin extrusion 1 (MATE1) and MATE2K proteins. In summary, these in vitro findings indicate that CYP3A4 and CYP3A5 mediate the metabolism of doravirine, although with different catalytic efficiencies. Clinical trials reported elsewhere confirm that doravirine is subject to drug-drug interactions (DDIs) via CYP3A inhibitors and inducers, but they support the notion that DDIs (either direction) are unlikely via other major drug-metabolizing enzymes and transporters.

Role of transporters in the disposition of a novel ß-lactamase inhibitor: relebactam (MK-7655).

OBJECTIVES: To identify the transporters involved in renal elimination of relebactam, and to assess the potential of relebactam as a perpetrator or victim of drug-drug interactions (DDIs) for major drug transporters. METHODS: A series of bidirectional transport, uptake and inhibition studies were conducted in vitro using transfected cell lines and membrane vesicles. The inhibitory effects of relebactam on major drug transporters, as well as the inhibitory effects of commonly used antibiotics/antifungals on organic anion transporter (OAT) 3-mediated uptake of relebactam, were assessed. RESULTS: Relebactam was shown to be a substrate of OAT3, OAT4, and multidrug and toxin extrusion (MATE) proteins MATE1 and MATE2K. Relebactam did not show profound inhibition across a panel of transporters, including organic anion-transporting polypeptides 1B1 and 1B3, OAT1, OAT3, organic cation transporter 2, MATE1, MATE2K, breast cancer resistance protein, multidrug resistance protein 1 and the bile salt export pump. Among the antibiotics/antifungals assessed for potential DDIs, probenecid demonstrated the most potent in vitro inhibition of relebactam uptake; however, such in vitro data did not translate into clinically relevant DDIs, suggesting that relebactam can be co-administered with OAT inhibitors, such as probenecid. CONCLUSIONS: Overall, relebactam has low potential to be a victim or perpetrator of DDIs with major drug transporters.

Genetic regulators of large-scale transcriptional signatures in cancer.

Gene expression signatures encompassing dozens to hundreds of genes have been associated with many important parameters of cancer, but mechanisms of their control are largely unknown. Here we present a method based on genetic linkage that can prospectively identify functional regulators driving large-scale transcriptional signatures in cancer. Using this method we show that the wound response signature, a poor-prognosis expression pattern of 512 genes in breast cancer, is induced by coordinate amplifications of MYC and CSN5 (also known as JAB1 or COPS5). This information enabled experimental recapitulation, functional assessment and mechanistic elucidation of the wound signature in breast epithelial cells.

Transcriptome sequencing in Sezary syndrome identifies Sezary cell and mycosis fungoides-associated lncRNAs and novel transcripts.

Sézary syndrome (SS) is an aggressive cutaneous T-cell lymphoma (CTCL) of unknown etiology in which malignant cells circulate in the peripheral blood. To identify viral elements, gene fusions, and gene expression patterns associated with this lymphoma, flow cytometry was used to obtain matched pure populations of malignant Sézary cells (SCs) versus nonmalignant CD4(+) T cells from 3 patients for whole transcriptome, paired-end sequencing with an average depth of 112 million reads per sample. Pathway analysis of differentially expressed genes identified mis-regulation of PI3K/Akt, TGFß, and NF-κB pathways as well as T-cell receptor signaling. Bioinformatic analysis did not detect either nonhuman transcripts to support a viral etiology of SS or recurrently expressed gene fusions, but it did identify 21 SC-associated annotated long noncoding RNAs (lncRNAs). Transcriptome assembly by multiple algorithms identified 13 differentially expressed unannotated transcripts termed Sézary cell-associated transcripts (SeCATs) that include 12 predicted lncRNAs and a novel transcript with coding potential. High-throughput sequencing targeting the 3' end of polyadenylated transcripts in archived tumors from 24 additional patients with tumor-stage CTCL confirmed the differential expression of SC-associated lncRNAs and SeCATs in CTCL. Our findings characterize the SS transcriptome and support recent reports that implicate lncRNA dysregulation in human malignancies.

Insecticidal Activity and Molecular Target by Morphological Analysis, RNAseq, and Molecular Docking of the Aryltetralin Lignan Lactone Helioxanthin, Isolated from Taiwania flousiana Gaussen.

Botanical insecticides are considered an environmentally friendly approach to insect control because they are easily biodegraded and cause less environmental pollution compared to traditional chemical pesticides. In this study, we reported the insecticidal activities of the ingredients from Taiwania flousiana Gaussen (T. flousiana). Five compounds, namely helioxanthin (C1), taiwanin E (C2), taiwanin H (C3), 7,4'-dimethylamentoflavone (C4), and 7,7″-di-O-methylamentoflavone (C5), were isolated and tested against the second, third, and fourth instar larvae of Aedes aegypti. Our results indicated that all five compounds showed insecticidal activities, and helioxanthin, which is an aryltetralin lignan lactone, was the most effective with LC50 values of 0.60, 2.82, and 3.12 mg/L, respectively, 48 h after application, with its activity against the second instar larvae similar to that of pyrethrin and better than that of rotenone. Further studies found that helioxanthin accumulated in the gastric cecum and the midgut and caused swelling of mitochondria with shallow matrices and fewer or disappeared crista. Additionally, our molecular mechanisms studies indicated that the significantly differentially expressed genes (DEGs) were mainly associated with mitochondria and the cuticle, among which the voltage-dependent anion-selective channel (VDAC) gene was the most down-regulated by helioxanthin, and VDAC is the potential target of helioxanthin by binding to specific amino acid residues (His 122 and Glu 147) via hydrogen bonds. We conclude that aryltetralin lignan lactone is a potential class of novel insecticides by targeting VDAC.

Rational design of bifunctional hydroxide/sulfide heterostructured catalyst for efficient electrochemical seawater splitting.

Heterostructure engineering is one of the most promising strategies for efficient water splitting by electrocatalysts. However, it remains challenging to design heterostructured catalysts to achieve the desired goals in both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in seawater splitting. Here, particulate heterostructures of FeCoNi hydroxide/sulfide supported on nickel foams were prepared by hydrothermal methods to achieve a high-performance bifunctional catalyst. The synthesized FeCoNi hydroxide/sulfide exhibited excellent electrocatalytic performance, requiring an overpotential of 195 mV for OER and 76 mV for HER to achieve a current density of 10 mA cm-2 while showing excellent stability. The catalyst maintains its excellent performance even in artificial or natural seawater with high salinity, which is a harsh environment. When applied directly to a water splitting system, the catalyst achieves a current density of 10 mA cm-2 at only 1.5 V (1.57 V in alkaline seawater). The FeCoNi hydroxide/sulfide heterostructure is an excellent electrocatalytic bifunctional catalyst due to compositional modulation, systematic charge transfer optimization, improved intermediates adsorption, and increased electrocatalytic active sites and the synergistic effect of the heterostructure.

In Vitro Assessment of Transporter Mediated Perpetrator DDIs for Several Hepatitis C Virus Direct-Acting Antiviral Drugs and Prediction of DDIs with Statins Using Static Models.

Inhibitory effects of asunaprevir, daclatasvir, grazoprevir, paritaprevir, simeprevir, and voxilaprevir, direct-acting antiviral (DAA) drugs for the treatment of chronic hepatitis C virus (HCV) infection, were evaluated in vitro against a range of clinically important drug transporters. In vitro inhibition studies were conducted using transporter transfected cells and membrane vesicles. The risk of clinical drug-drug interactions (DDIs) was assessed using simplified static models recommended by regulatory agencies. Furthermore, we refined and developed static models to predict complex DDIs with several statins (pitavastatin, rosuvastatin, atorvastatin, and pravastatin) by mechanistically assessing differential inhibitory effects of perpetrator drugs on multiple transporters, such as organic anion transporting polypeptides (OATP1B), breast cancer resistance protein (BCRP), multidrug resistance protein 2 (MRP2), organic anion transporter 3 (OAT3), and cytochrome P450 CYP3A enzyme, as they are known to contribute to absorption, distribution, metabolism and excretion (ADME) of above statins. These models successfully predicted a total of 46 statin DDIs, including above DAA drugs and their fix-dose combination regimens. Predicted plasma area under curve ratio (AUCR) with and without perpetrator drugs was within ~ 2-fold of observed values. In contrast, simplified static R-value model resulted in increased false negative and false positive predictions when different prediction cut-off values were applied. Our studies suggest that mechanistic static model is a promising and useful tool to provide more accurate prediction of the risk and magnitude of DDIs with statins in early drug development and may help to improve the management of clinical DDIs for HCV drugs to ensure effective and safe HCV therapy. GRAPHICAL ABSTRACT.

Near-infrared responsive sulfur vacancy-rich CuS nanosheets for efficient antibacterial activity via synergistic photothermal and photodynamic pathways.

Defect engineering has been proven to be an effective approach for electronic structure modulation and plays an important role in the photocatalytic performance of nanomaterials. In this study, a series of CuS nanosheet sulfur vacancies (VS) are constructed by a simple hydrothermal synthesis method. The CuS with the highest VS concentration exhibits strong antibacterial performance, achieving bactericidal rates of 99.9% against the Gram-positive Bacillus subtilis and Gram-negative Escherichia coli bacteria under 808 nm laser irradiation. Under illumination, the temperature of the catalyst increases from 23.5 °C to 53.3 °C, and with a high photothermal conversion efficiency of 41.8%. For E. coli and B. subtilis, the reactive oxygen species (ROS) production that is induced by the CuS group is 8.6 and 9.6 times greater, respectively, than that of the control group. The presence of VS facilitates the enhancement of the light absorption capacity and the separation efficiency of electron-hole pairs, thereby resulting in improved photocatalytic performance. The synergistic effect of photothermal therapy (PTT) and photodynamic therapy (PDT) is aimed at causing oxidative damage and leading to bacterial death. Our findings provide an effective antibacterial strategy and offer new horizons for the application of CuS catalysts with VS in the NIR region.

Berberine is a novel cholesterol-lowering drug working through a unique mechanism distinct from statins.

We identify berberine (BBR), a compound isolated from a Chinese herb, as a new cholesterol-lowering drug. Oral administration of BBR in 32 hypercholesterolemic patients for 3 months reduced serum cholesterol by 29%, triglycerides by 35% and LDL-cholesterol by 25%. Treatment of hyperlipidemic hamsters with BBR reduced serum cholesterol by 40% and LDL-cholesterol by 42%, with a 3.5-fold increase in hepatic LDLR mRNA and a 2.6-fold increase in hepatic LDLR protein. Using human hepatoma cells, we show that BBR upregulates LDLR expression independent of sterol regulatory element binding proteins, but dependent on ERK activation. BBR elevates LDLR expression through a post-transcriptional mechanism that stabilizes the mRNA. Using a heterologous system with luciferase as a reporter, we further identify the 5' proximal section of the LDLR mRNA 3' untranslated region responsible for the regulatory effect of BBR. These findings show BBR as a new hypolipidemic drug with a mechanism of action different from that of statin drugs.

Islatravir Is Not Expected to Be a Victim or Perpetrator of Drug-Drug Interactions via Major Drug-Metabolizing Enzymes or Transporters.

Islatravir (MK-8591) is a nucleoside reverse transcriptase translocation inhibitor in development for the treatment and prevention of HIV-1. The potential for islatravir to interact with commonly co-prescribed medications was studied in vitro. Elimination of islatravir is expected to be balanced between adenosine deaminase-mediated metabolism and renal excretion. Islatravir did not inhibit uridine diphosphate glucuronosyltransferase 1A1 or cytochrome p450 (CYP) enzymes CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6, or 3A4, nor did it induce CYP1A2, 2B6, or 3A4. Islatravir did not inhibit hepatic transporters organic anion transporting polypeptide (OATP) 1B1, OATP1B3, organic cation transporter (OCT) 1, bile salt export pump (BSEP), multidrug resistance-associated protein (MRP) 2, MRP3, or MRP4. Islatravir was neither a substrate nor a significant inhibitor of renal transporters organic anion transporter (OAT) 1, OAT3, OCT2, multidrug and toxin extrusion protein (MATE) 1, or MATE2K. Islatravir did not significantly inhibit P-glycoprotein and breast cancer resistance protein (BCRP); however, it was a substrate of BCRP, which is not expected to be of clinical significance. These findings suggest islatravir is unlikely to be the victim or perpetrator of drug-drug interactions with commonly co-prescribed medications, including statins, diuretics, anti-diabetic drugs, proton pump inhibitors, anticoagulants, benzodiazepines, and selective serotonin reuptake inhibitors.

Blockage of oncostatin M-induced LDL receptor gene transcription by a dominant-negative mutant of C/EBPbeta.

OM (oncostatin M) activates the human LDLR [LDL (low-density lipoprotein) receptor] gene transcription in HepG2 cells through the SIRE (sterol-independent regulatory element) of LDLR promoter. The SIRE sequence consists of a C/EBP (CCAAT/enhancer-binding protein)-binding site and a CRE (cAMP-response element). Our previous studies [Zhang, Ahlborn, Li, Kraemer and Liu (2002) J. Lipid Res. 43, 1477-1485; Zhang, Lin, Abidi, Thiel and Liu (2003) J. Biol. Chem. 278, 44246-44254] have demonstrated that OM transiently induces EGR-1 (early growth response gene product 1) expression and EGR-1 activates LDLR transcription primarily through a protein-protein interaction with C/EBPbeta, which serves as a co-activator of EGR-1. In the present study, we examined the direct role of C/EBPbeta as a transactivator in OM-regulated LDLR gene transcription independent of EGR-1. We show that OM induces C/EBPbeta expression with kinetics slower than EGR-1 induction. A significant increase in C/EBPbeta protein level is detected by 2 h of OM treatment and remains elevated for 24 h. Chromatin immunoprecipitation assays demonstrate that the amount of C/EBPbeta bound to the LDLR SIRE sequence is increased 2.8-fold of control by 2 h of OM treatment, reached the highest level of 8-fold by 4 h, and slowly declined thereafter. To further examine the requirement of C/EBPbeta in OM-stimulated LDLR expression, we developed a His-tagged dominant-negative mutant of C/EBPbeta (His-C/EBPbeta-P4; where P4 is plasmid 4 in our mutation series), consisting of the DNA-binding and leucine zipper domains of C/EBPbeta (amino acids 246-345). Expression of His-C/EBPbeta-P4 in HepG2 cells significantly diminishes the OM-induced increase in LDLR promoter activity and the elevation of endogenous LDLR mRNA expression. Taken together, these new findings identify C/EBPbeta as an OM-induced transactivator in LDLR gene transcription and provide a better understanding of the molecular mechanism underlying the sterol-independent regulation of LDLR expression.

Identification of PRC1 as the p53 target gene uncovers a novel function of p53 in the regulation of cytokinesis.

Our previous studies conducted in MCF7-ptsp53 cells have demonstrated that overexpression of the wild-type (wt) p53 at permissive temperature 32 degrees C leads to growth arrest at the G2/M phase of the cell cycle. To identify novel p53-regulated genes that are responsible for the p53-induced G2/M arrest, we conducted cDNA microarray analyses. The array results indicated that the mRNA level of protein regulator of cytokinesis (PRC1) was significantly decreased when the p53 transactivation activity was turned on, suggesting that PRC1 transcription could be downregulated by p53. In this study, we have extensively examined the functional role of p53 in the regulation of PRC1, a cell cycle protein that plays important roles during cytokinesis. We demonstrate that increased expression of the wt p53 either by exogenous transfection or chemical induction results in reduced mRNA and protein expression of PRC1 in HCT116 p53(+/+), HCT116 p53(-/-), MCF-7, T47D, and HeLa cells. Importantly, we show that the decreased PRC1 expression is accompanied by the appearance of binucleated cells, indicating the process of cell division after mitosis being inhibited. By isolation and characterization of a 3 kb genomic fragment containing the 5'-flanking region and part of exon 1 of PRC1 gene, we demonstrate that p53 directly suppresses PRC1 gene transcription. We further locate the p53-responsive sequence to the proximal promoter region -214 to -163, relative to the transcriptional start site. The in vivo interaction of p53 with PRC1 gene promoter is further demonstrated by chromatin immunoprecipitation assay. Taken together, these new findings suggest that p53 may have important roles in the regulation of cytokinesis through controlling the transcription of PRC1.

Synergistic activation of human LDL receptor expression by SCAP ligand and cytokine oncostatin M.

OBJECTIVE: A recent study identified a new class of compounds designated as the sterol-regulatory element binding protein (SREBP) cleavage-activating protein (SCAP) ligands that putatively bind to SCAP, leading to increased LDL receptor (LDLR) expression. In this study, we examined the effects of SCAP ligand GW707 in comparison with lovastatin and cytokine oncostatin M (OM) on the regulation of LDLR expression in cultured HepG2 cells. METHODS AND RESULTS: Our studies uncovered several new features that distinguish SCAP ligand from lovastatin, a classic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, and from OM, which utilize an SREBP-independent regulatory pathway. We show that the induction of LDLR mRNA expression by GW707 is not affected by intracellular cholesterol but is completely abolished by blocking de novo protein synthesis. Moreover, the effects of GW707 but not lovastatin on LDLR promoter activity, mRNA expression, and uptake of 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanin perchlorate-LDL are markedly enhanced by OM. We further demonstrate that the amounts of the mature form of SREBP-2 translocated to the nucleus under GW707 treatment are increased by costimulating cells with OM. CONCLUSIONS: Our studies provide the first evidence that higher levels of LDLR expression and function can be achieved through simultaneous stimulation of the SREBP-dependent and SREBP-independent pathways, suggesting a strategy to develop an adjunct therapeutic intervention utilizing both pathways.

Rejuvenation of gene expression pattern of aged human skin by broadband light treatment: a pilot study.

Studies in model organisms suggest that aged cells can be functionally rejuvenated, but whether this concept applies to human skin is unclear. Here we apply 3'-end sequencing for expression quantification ("3-seq") to discover the gene expression program associated with human photoaging and intrinsic skin aging (collectively termed "skin aging"), and the impact of broadband light (BBL) treatment. We find that skin aging was associated with a significantly altered expression level of 2,265 coding and noncoding RNAs, of which 1,293 became "rejuvenated" after BBL treatment; i.e., they became more similar to their expression level in youthful skin. Rejuvenated genes (RGs) included several known key regulators of organismal longevity and their proximal long noncoding RNAs. Skin aging is not associated with systematic changes in 3'-end mRNA processing. Hence, BBL treatment can restore gene expression pattern of photoaged and intrinsically aged human skin to resemble young skin. In addition, our data reveal, to our knowledge, a previously unreported set of targets that may lead to new insights into the human skin aging process.

Targeted disruption of Hotair leads to homeotic transformation and gene derepression.

Long noncoding RNAs (lncRNAs) are thought to be prevalent regulators of gene expression, but the consequences of lncRNA inactivation in vivo are mostly unknown. Here, we show that targeted deletion of mouse Hotair lncRNA leads to derepression of hundreds of genes, resulting in homeotic transformation of the spine and malformation of metacarpal-carpal bones. RNA sequencing and conditional inactivation reveal an ongoing requirement of Hotair to repress HoxD genes and several imprinted loci such as Dlk1-Meg3 and Igf2-H19 without affecting imprinting choice. Hotair binds to both Polycomb repressive complex 2, which methylates histone H3 at lysine 27 (H3K27), and Lsd1 complex, which demethylates histone H3 at lysine 4 (H3K4) in vivo. Hotair inactivation causes H3K4me3 gain and, to a lesser extent, H3K27me3 loss at target genes. These results reveal the function and mechanisms of Hotair lncRNA in enforcing a silent chromatin state at Hox and additional genes.

CSN5 isopeptidase activity links COP9 signalosome activation to breast cancer progression.

CSN5 has been implicated as a candidate oncogene in human breast cancers by genetic linkage with activation of the poor-prognosis, wound response gene expression signature. CSN5 is a subunit of the eight-protein COP9 signalosome, a signaling complex with multiple biochemical activities; the mechanism of CSN5 action in cancer development remains poorly understood. Here, we show that CSN5 isopeptidase activity is essential for breast epithelial transformation and progression. Amplification of CSN5 is required for transformation of primary human breast epithelial cells by defined oncogenes. The transforming effects of CSN5 require CSN subunits for assembly of the full COP9 signalosome and the isopeptidase activity of CSN5, which potentiates the transcriptional activity of MYC. Transgenic inhibition of CSN5 isopeptidase activity blocks breast cancer progression evoked by MYC and RAS in vivo. These results highlight CSN5 isopeptidase activity in breast cancer progression, suggesting it as a therapeutic target in aggressive human breast cancers.