ABSTRACT
Transcriptome analyses show a surprisingly large proportion of the mammalian genome is transcribed; much more than can be accounted for by genes and introns alone. Most of this transcription is non-coding in nature and arises from intergenic regions, often overlapping known protein-coding genes in sense or antisense orientation. The functional relevance of this widespread transcription is unknown. Here we characterize a promoter responsible for initiation of an intergenic transcript located approximately 3.3 kb and 10.7 kb upstream of the adult-specific human ß-globin genes. Mutational analyses in ß-YAC transgenic mice show that alteration of intergenic promoter activity results in ablation of H3K4 di- and tri-methylation and H3 hyperacetylation extending over a 30 kb region immediately downstream of the initiation site, containing the adult δ- and ß-globin genes. This results in dramatically decreased expression of the adult genes through position effect variegation in which the vast majority of definitive erythroid cells harbor inactive adult globin genes. In contrast, expression of the neighboring ε- and γ-globin genes is completely normal in embryonic erythroid cells, indicating a developmentally specific variegation of the adult domain. Our results demonstrate a role for intergenic non-coding RNA transcription in the propagation of histone modifications over chromatin domains and epigenetic control of ß-like globin gene transcription during development.
Subject(s)
Chromatin/genetics , DNA, Intergenic/genetics , Gene Expression Regulation, Developmental , Histones/chemistry , Promoter Regions, Genetic , RNA, Untranslated/genetics , beta-Globins/genetics , Adult , Animals , Chromosomes, Artificial, Yeast , Erythroid Cells/metabolism , Humans , Mice , Mice, Transgenic , Transcription, GeneticABSTRACT
With the advent of novel designer molecules for cystic fibrosis (CF) treatment, there is huge need for early-life clinical trial outcomes, such as infant lung function (ILF). We investigated the degree and tracking of ILF abnormality during the first 2â years of life in CF newborn screened infants.Forced expiratory volume in 0.5â s (FEV0.5), lung clearance index (LCI) and plethysmographic functional residual capacity were measured at â¼3â months, 1â year and 2â years in 62 infants with CF and 34 controls.By 2â years there was no significant difference in FEV0.5 z-score between CF and controls, whereas mean LCI z-score was 0.81 (95% CI 0.45-1.17) higher in CF. However, there was no significant association between LCI z-score at 2â years with either 3-month or 1-year results. Despite minimal average group changes in any ILF outcome during the second year of life, marked within-subject changes occurred. No child had abnormal LCI or FEV0.5 on all test occasions, precluding the ability to identify "high-risk" infants in early life.In conclusion, changes in lung function are mild and transient during the first 2â years of life in newborn screened infants with CF when managed according to a standardised UK treatment protocol. Their potential role in tracking disease to later childhood will be ascertained by ongoing follow-up.
Subject(s)
Cystic Fibrosis/diagnosis , Cystic Fibrosis/physiopathology , Lung/physiopathology , Neonatal Screening , Case-Control Studies , Female , Forced Expiratory Volume , Functional Residual Capacity , Humans , Infant , Infant, Newborn , Male , Regression Analysis , United KingdomABSTRACT
Nationally, death rates from prescription opioid pain reliever (OPR) overdoses quadrupled during 1999-2010, whereas rates from heroin overdoses increased by <50%. Individual states and cities have reported substantial increases in deaths from heroin overdose since 2010. CDC analyzed recent mortality data from 28 states to determine the scope of the heroin overdose death increase and to determine whether increases were associated with changes in OPR overdose death rates since 2010. This report summarizes the results of that analysis, which found that, from 2010 to 2012, the death rate from heroin overdose for the 28 states increased from 1.0 to 2.1 per 100,000, whereas the death rate from OPR overdose declined from 6.0 per 100,000 in 2010 to 5.6 per 100,000 in 2012. Heroin overdose death rates increased significantly for both sexes, all age groups, all census regions, and all racial/ethnic groups other than American Indians/Alaska Natives. OPR overdose mortality declined significantly among males, persons aged <45 years, persons in the South, and non-Hispanic whites. Five states had increases in the OPR death rate, seven states had decreases, and 16 states had no change. Of the 18 states with statistically reliable heroin overdose death rates (i.e., rates based on at least 20 deaths), 15 states reported increases. Decreases in OPR death rates were not associated with increases in heroin death rates. The findings indicate a need for intensified prevention efforts aimed at reducing overdose deaths from all types of opioids while recognizing the demographic differences between the heroin and OPR-using populations. Efforts to prevent expansion of the number of OPR users who might use heroin when it is available should continue.
Subject(s)
Drug Overdose/mortality , Heroin/poisoning , Adolescent , Adult , Age Distribution , Drug Overdose/ethnology , Ethnicity/statistics & numerical data , Female , Humans , Male , Middle Aged , Racial Groups/statistics & numerical data , Sex Distribution , United States/epidemiology , Young AdultABSTRACT
Several lines of evidence have established strong links between transcriptional activity and specific post-translation modifications of histones. Here we show using RNA FISH that in erythroid cells, intergenic transcription in the human beta-globin locus occurs over a region of greater than 250 kb including several genes in the nearby olfactory receptor gene cluster. This entire region is transcribed during S phase of the cell cycle. However, within this region there are approximately 20 kb sub-domains of high intergenic transcription that occurs outside of S phase. These sub-domains are developmentally regulated and enriched with high levels of active modifications primarily to histone H3. The sub-domains correspond to the beta-globin locus control region, which is active at all developmental stages in erythroid cells, and the region flanking the developmentally regulated, active globin genes. These results correlate high levels of non-S phase intergenic transcription with domain-wide active histone modifications to histone H3.
Subject(s)
Cell Cycle/physiology , Transcription, Genetic , beta-Globins/genetics , Adult , Anemia/genetics , Animals , Chromosome Mapping/methods , DNA Primers , DNA, Complementary/genetics , Gene Expression Profiling/methods , Humans , Introns/genetics , Mice , Mice, Transgenic , RNA/blood , RNA/genetics , RNA/isolation & purification , Reverse Transcriptase Polymerase Chain Reaction , S Phase/physiology , Smell/geneticsABSTRACT
The beta-globin genes have become a classical model for studying regulation of gene expression. Wide-ranging studies have revealed multiple levels of epigenetic regulation that coordinately ensure a highly specialised, tissue- and stage-specific gene transcription pattern. Key players include cis-acting elements involved in establishing and maintaining specific chromatin conformations and histone modification patterns, elements engaged in the transcription process through long-range regulatory interactions, transacting general and tissue-specific factors. On a larger scale, molecular events occurring at the locus level take place in the context of a highly dynamic nucleus as part of the cellular epigenetic programme.
Subject(s)
Epigenesis, Genetic , Gene Expression Regulation, Developmental , Globins/genetics , Animals , Cell Cycle/physiology , Humans , Insulator Elements , Locus Control Region , Macromolecular Substances , Multigene Family , Promoter Regions, Genetic , Transcription, Genetic , TransgenesABSTRACT
Polysaccharides containing beta-1,4-mannosyl residues (mannans) are abundant in the lignified secondary cell walls of gymnosperms, and are also found as major seed storage polysaccharides in some plants, such as legume species. Although they have been found in a variety of angiosperm tissues, little is known about their presence and tissue localisation in the model angiosperm, Arabidopsis thaliana (L.) Heynh. In this study, antibodies that specifically recognised mannans in competitive ELISA experiments were raised in rabbits. Using these antibodies, we showed that Golgi-rich vesicles derived from Arabidopsis callus were able to synthesise mannan polysaccharides in vitro. Immunofluorescence light microscopy and immunogold electron microscopy of Arabidopsis inflorescence stem sections revealed that the mannan polysaccharide epitopes were localised in the thickened secondary cell walls of xylem elements, xylem parenchyma and interfascicular fibres. Similarly, mannan epitopes were present in the xylem of the leaf vascular bundles. Surprisingly, the thickened epidermal cell walls of both leaves and stems also contained abundant mannan epitopes. Low levels were observed in most other cell types examined. Thus, mannans are widespread in Arabidopsis tissues, and may be of particular significance in both lignified and non-lignified thickened cell walls. Polysaccharide analysis using carbohydrate gel electrophoresis (PACE) of cell wall preparations digested with a specific mannanase showed that there is glucomannan in inflorescence stems. The findings show that Arabidopsis can be used as a model plant in studies of the synthesis and functions of mannans.