TY - JOUR T1 - Genomic variation. Impact of regulatory variation from RNA to protein. JF - Science Y1 - 2015 A1 - Battle, Alexis A1 - Khan, Zia A1 - Wang, Sidney H A1 - Mitrano, Amy A1 - Ford, Michael J A1 - Pritchard, Jonathan K A1 - Gilad, Yoav KW - 3' Flanking Region KW - 5' Flanking Region KW - Cell Line KW - Exons KW - Gene Expression Regulation KW - Genetic Variation KW - HUMANS KW - PHENOTYPE KW - Protein Biosynthesis KW - Quantitative Trait Loci KW - Ribosomes KW - RNA, Messenger KW - Transcription, Genetic AB -

The phenotypic consequences of expression quantitative trait loci (eQTLs) are presumably due to their effects on protein expression levels. Yet the impact of genetic variation, including eQTLs, on protein levels remains poorly understood. To address this, we mapped genetic variants that are associated with eQTLs, ribosome occupancy (rQTLs), or protein abundance (pQTLs). We found that most QTLs are associated with transcript expression levels, with consequent effects on ribosome and protein levels. However, eQTLs tend to have significantly reduced effect sizes on protein levels, which suggests that their potential impact on downstream phenotypes is often attenuated or buffered. Additionally, we identified a class of cis QTLs that affect protein abundance with little or no effect on messenger RNA or ribosome levels, which suggests that they may arise from differences in posttranslational regulation.

VL - 347 CP - 6222 M3 - 10.1126/science.1260793 ER - TY - Generic T1 - Developmental expression of chicken FOXN1 and putative target genes during feather development. Y1 - 2014 A1 - Darnell, Diana K A1 - Zhang, Li S A1 - Hannenhalli, Sridhar A1 - Yaklichkin, Sergey Y KW - Amino Acid Sequence KW - Animals KW - Biological Evolution KW - Blotting, Western KW - Cell Differentiation KW - Cells, Cultured KW - Chick Embryo KW - Chickens KW - Cloning, Molecular KW - Embryo, Nonmammalian KW - Epidermis KW - Feathers KW - Forkhead Transcription Factors KW - Gene Expression Regulation, Developmental KW - In Situ Hybridization KW - Molecular Sequence Data KW - Morphogenesis KW - Phylogeny KW - Real-Time Polymerase Chain Reaction KW - Reverse Transcriptase Polymerase Chain Reaction KW - RNA, Messenger KW - Sequence Homology, Amino Acid AB -

FOXN1 is a member of the forkhead box family of transcription factors. FOXN1 is crucial for hair outgrowth and thymus differentiation in mammals. Unlike the thymus, which is found in all amniotes, hair is an epidermal appendage that arose after the last shared common ancestor between mammals and birds, and hair and feathers differ markedly in their differentiation and gene expression. Here, we show that FOXN1 is expressed in embryonic chicken feathers, nails and thymus, demonstrating an evolutionary conservation that goes beyond obvious homology. At embryonic day (ED) 12, FOXN1 is expressed in some feather buds and at ED13 expression extends along the length of the feather filament. At ED14 FOXN1 mRNA is restricted to the proximal feather filament and is not detectable in distal feather shafts. At the base of the feather, FOXN1 is expressed in the epithelium of the feather sheath and distal barb and marginal plate, whereas in the midsection FOXN1 transcripts are mainly detected in the barb plates of the feather filament. FOXN1 is also expressed in claws; however, no expression was detected in skin or scales. Despite expression of FOXN1 in developing feathers, examination of chick homologs of five putative mammalian FOXN1 target genes shows that, while these genes are expressed in feathers, there is little similarity to the FOXN1 expression pattern, suggesting that some gene regulatory networks may have diverged during evolution of epidermal appendages.

JA - Int J Dev Biol VL - 58 CP - 1 M3 - 10.1387/ijdb.130023sy ER - TY - JOUR T1 - Primate transcript and protein expression levels evolve under compensatory selection pressures. JF - Science Y1 - 2013 A1 - Khan, Zia A1 - Ford, Michael J A1 - Cusanovich, Darren A A1 - Mitrano, Amy A1 - Pritchard, Jonathan K A1 - Gilad, Yoav KW - Animals KW - Evolution, Molecular KW - Gene Expression Regulation KW - HUMANS KW - Macaca mulatta KW - Pan troglodytes KW - Protein Biosynthesis KW - RNA, Messenger KW - Selection, Genetic KW - Species Specificity KW - Transcription, Genetic AB -

Changes in gene regulation have likely played an important role in the evolution of primates. Differences in messenger RNA (mRNA) expression levels across primates have often been documented; however, it is not yet known to what extent measurements of divergence in mRNA levels reflect divergence in protein expression levels, which are probably more important in determining phenotypic differences. We used high-resolution, quantitative mass spectrometry to collect protein expression measurements from human, chimpanzee, and rhesus macaque lymphoblastoid cell lines and compared them to transcript expression data from the same samples. We found dozens of genes with significant expression differences between species at the mRNA level yet little or no difference in protein expression. Overall, our data suggest that protein expression levels evolve under stronger evolutionary constraint than mRNA levels.

VL - 342 CP - 6162 M3 - 10.1126/science.1242379 ER - TY - JOUR T1 - Genomic organization and expression profile of the mucin-associated surface protein (masp) family of the human pathogen Trypanosoma cruzi. JF - Nucleic Acids Res Y1 - 2009 A1 - Bartholomeu, Daniella C A1 - Cerqueira, Gustavo C A1 - Leão, Ana Carolina A A1 - daRocha, Wanderson D A1 - Pais, Fabiano S A1 - Macedo, Camila A1 - Djikeng, Appolinaire A1 - Teixeira, Santuza M R A1 - El-Sayed, Najib M KW - 3' Flanking Region KW - 5' Flanking Region KW - Amino Acid Sequence KW - Animals KW - Base Sequence KW - Conserved Sequence KW - Gene Expression Profiling KW - Genes, Protozoan KW - Genome, Protozoan KW - Membrane Proteins KW - Molecular Sequence Data KW - Mucins KW - Multigene Family KW - Protozoan Proteins KW - RNA, Messenger KW - Trypanosoma cruzi AB -

A novel large multigene family was recently identified in the human pathogen Trypanosoma cruzi, causative agent of Chagas disease, and corresponds to approximately 6% of the parasite diploid genome. The predicted gene products, mucin-associated surface proteins (MASPs), are characterized by highly conserved N- and C-terminal domains and a strikingly variable and repetitive central region. We report here an analysis of the genomic organization and expression profile of masp genes. Masps are not randomly distributed throughout the genome but instead are clustered with genes encoding mucin and other surface protein families. Masp transcripts vary in size, are preferentially expressed during the trypomastigote stage and contain highly conserved 5' and 3' untranslated regions. A sequence analysis of a trypomastigote cDNA library reveals the expression of multiple masp variants with a bias towards a particular masp subgroup. Immunofluorescence assays using antibodies generated against a MASP peptide reveals that the expression of particular MASPs at the cell membrane is limited to subsets of the parasite population. Western blots of phosphatidylinositol-specific phospholipase C (PI-PLC)-treated parasites suggest that MASP may be GPI-anchored and shed into the medium culture, thus contributing to the large repertoire of parasite polypeptides that are exposed to the host immune system.

VL - 37 CP - 10 M3 - 10.1093/nar/gkp172 ER - TY - JOUR T1 - Features generated for computational splice-site prediction correspond to functional elements. JF - BMC Bioinformatics Y1 - 2007 A1 - Dogan, Rezarta Islamaj A1 - Getoor, Lise A1 - Wilbur, W John A1 - Mount, Stephen M KW - Computational Biology KW - HUMANS KW - Predictive Value of Tests KW - RNA Splice Sites KW - RNA, Messenger AB -

BACKGROUND: Accurate selection of splice sites during the splicing of precursors to messenger RNA requires both relatively well-characterized signals at the splice sites and auxiliary signals in the adjacent exons and introns. We previously described a feature generation algorithm (FGA) that is capable of achieving high classification accuracy on human 3' splice sites. In this paper, we extend the splice-site prediction to 5' splice sites and explore the generated features for biologically meaningful splicing signals.

RESULTS: We present examples from the observed features that correspond to known signals, both core signals (including the branch site and pyrimidine tract) and auxiliary signals (including GGG triplets and exon splicing enhancers). We present evidence that features identified by FGA include splicing signals not found by other methods.

CONCLUSION: Our generated features capture known biological signals in the expected sequence interval flanking splice sites. The method can be easily applied to other species and to similar classification problems, such as tissue-specific regulatory elements, polyadenylation sites, promoters, etc.

VL - 8 M3 - 10.1186/1471-2105-8-410 ER - TY - JOUR T1 - Members of a large retroposon family are determinants of post-transcriptional gene expression in Leishmania. JF - PLoS Pathog Y1 - 2007 A1 - Bringaud, Frederic A1 - Müller, Michaela A1 - Cerqueira, Gustavo Coutinho A1 - Smith, Martin A1 - Rochette, Annie A1 - el-Sayed, Najib M A A1 - Papadopoulou, Barbara A1 - Ghedin, Elodie KW - 3' Untranslated Regions KW - Animals KW - Base Sequence KW - Biological Evolution KW - Down-Regulation KW - Gene Expression Regulation KW - Genome, Protozoan KW - Leishmania KW - Leishmania major KW - Molecular Sequence Data KW - Retroelements KW - RNA, Messenger KW - sequence alignment KW - Trypanosoma brucei brucei KW - Trypanosoma cruzi AB -

Trypanosomatids are unicellular protists that include the human pathogens Leishmania spp. (leishmaniasis), Trypanosoma brucei (sleeping sickness), and Trypanosoma cruzi (Chagas disease). Analysis of their recently completed genomes confirmed the presence of non-long-terminal repeat retrotransposons, also called retroposons. Using the 79-bp signature sequence common to all trypanosomatid retroposons as bait, we identified in the Leishmania major genome two new large families of small elements--LmSIDER1 (785 copies) and LmSIDER2 (1,073 copies)--that fulfill all the characteristics of extinct trypanosomatid retroposons. LmSIDERs are approximately 70 times more abundant in L. major compared to T. brucei and are found almost exclusively within the 3'-untranslated regions (3'UTRs) of L. major mRNAs. We provide experimental evidence that LmSIDER2 act as mRNA instability elements and that LmSIDER2-containing mRNAs are generally expressed at lower levels compared to the non-LmSIDER2 mRNAs. The considerable expansion of LmSIDERs within 3'UTRs in an organism lacking transcriptional control and their role in regulating mRNA stability indicate that Leishmania have probably recycled these short retroposons to globally modulate the expression of a number of genes. To our knowledge, this is the first example in eukaryotes of the domestication and expansion of a family of mobile elements that have evolved to fulfill a critical cellular function.

VL - 3 CP - 9 M3 - 10.1371/journal.ppat.0030136 ER - TY - JOUR T1 - Trypanosoma cruzi: RNA structure and post-transcriptional control of tubulin gene expression. JF - Exp Parasitol Y1 - 2002 A1 - Bartholomeu, Daniella C A1 - Silva, Rosiane A A1 - Galvão, Lucia M C A1 - el-Sayed, Najib M A A1 - Donelson, John E A1 - Teixeira, Santuza M R KW - Animals KW - Base Sequence KW - Blotting, Northern KW - DNA, Complementary KW - DNA, Protozoan KW - Gene Expression Regulation KW - Half-Life KW - Life Cycle Stages KW - Molecular Sequence Data KW - RNA Processing, Post-Transcriptional KW - RNA, Messenger KW - RNA, Protozoan KW - Transcription, Genetic KW - Transfection KW - Trypanosoma cruzi KW - Tubulin AB -

Changes in tubulin expression are among the biochemical and morphological adaptations that occur during the life cycle of Trypanosomatids. To investigate the mechanism responsible for the differential accumulation of tubulin mRNAs in Trypanosoma cruzi, we determine the sequences of alpha- and beta-tubulin transcripts and analyzed their expression during the life cycle of the parasite. Two beta-tubulin mRNAs of 1.9 and 2.3 kb were found to differ mainly by an additional 369 nucleotides at the end of the 3' untranslated region (UTR). Although their transcription rates are similar in epimastigotes and amastigotes, alpha- and beta-tubulin transcripts are 3- to 6-fold more abundant in epimastigotes than in trypomastigotes and amastigotes. Accordingly, the half-lives of alpha- and beta-tubulin mRNAs are significantly higher in epimastigotes than in amastigotes. Transient transfection experiments indicated that positive regulatory elements occur in the 3' UTR plus downstream intergenic region of the alpha-tubulin gene and that both positive and negative elements occur in the equivalent regions of the beta-tubulin gene.

VL - 102 CP - 3-4 ER - TY - JOUR T1 - Pre-messenger RNA processing factors in the Drosophila genome. JF - J Cell Biol Y1 - 2000 A1 - Mount, S M A1 - Salz, H K KW - Animals KW - Drosophila melanogaster KW - Genome KW - Genomic Library KW - HUMANS KW - RNA Precursors KW - RNA, Messenger VL - 150 CP - 2 ER - TY - JOUR T1 - Splicing signals in Drosophila: intron size, information content, and consensus sequences. JF - Nucleic Acids Res Y1 - 1992 A1 - Mount, S M A1 - Burks, C A1 - Hertz, G A1 - Stormo, G D A1 - White, O A1 - Fields, C KW - Animals KW - Base Sequence KW - Consensus Sequence KW - Databases, Factual KW - Drosophila KW - Introns KW - Molecular Sequence Data KW - RNA Splicing KW - RNA, Messenger KW - software AB -

A database of 209 Drosophila introns was extracted from Genbank (release number 64.0) and examined by a number of methods in order to characterize features that might serve as signals for messenger RNA splicing. A tight distribution of sizes was observed: while the smallest introns in the database are 51 nucleotides, more than half are less than 80 nucleotides in length, and most of these have lengths in the range of 59-67 nucleotides. Drosophila splice sites found in large and small introns differ in only minor ways from each other and from those found in vertebrate introns. However, larger introns have greater pyrimidine-richness in the region between 11 and 21 nucleotides upstream of 3' splice sites. The Drosophila branchpoint consensus matrix resembles C T A A T (in which branch formation occurs at the underlined A), and differs from the corresponding mammalian signal in the absence of G at the position immediately preceding the branchpoint. The distribution of occurrences of this sequence suggests a minimum distance between 5' splice sites and branchpoints of about 38 nucleotides, and a minimum distance between 3' splice sites and branchpoints of 15 nucleotides. The methods we have used detect no information in exon sequences other than in the few nucleotides immediately adjacent to the splice sites. However, Drosophila resembles many other species in that there is a discontinuity in A + T content between exons and introns, which are A + T rich.

VL - 20 CP - 16 ER - TY - JOUR T1 - Polyadenylylation in copia requires unusually distant upstream sequences. JF - Proc Natl Acad Sci U S A Y1 - 1991 A1 - Kurkulos, M A1 - Weinberg, J M A1 - Pepling, M E A1 - Mount, S M KW - Animals KW - Base Sequence KW - Blotting, Northern KW - DNA Transposable Elements KW - Drosophila melanogaster KW - Eye Color KW - Molecular Sequence Data KW - Oligonucleotides KW - Polymerase Chain Reaction KW - Regulatory Sequences, Nucleic Acid KW - Repetitive Sequences, Nucleic Acid KW - RNA Processing, Post-Transcriptional KW - RNA, Messenger AB -

Retroviruses and related genetic elements generate terminally redundant RNA products by differential polyadenylylation within a long terminal repeat. Expression of the white-apricot (wa) allele of Drosophila melanogaster, which carries an insertion of the 5.1-kilobase retrovirus-like transposable element copia in a small intron, is influenced by signals within copia. By using this indicator, we have isolated a 518-base-pair deletion, 312 base pairs upstream of the copia polyadenylylation site, that is phenotypically like much larger deletions and eliminates RNA species polyadenylylated in copia. This requirement of distant upstream sequences for copia polyadenylylation has implications for the expression of many genetic elements bearing long terminal repeats.

VL - 88 CP - 8 ER - TY - JOUR T1 - Characterization of enhancer-of-white-apricot in Drosophila melanogaster. JF - Genetics Y1 - 1990 A1 - Peng, X B A1 - Mount, S M KW - Alleles KW - Animals KW - Blotting, Northern KW - DNA Transposable Elements KW - Drosophila melanogaster KW - Eye Color KW - Female KW - Heterozygote KW - Homozygote KW - Male KW - Nucleic Acid Hybridization KW - PHENOTYPE KW - Poly A KW - Reproduction KW - RNA KW - RNA, Messenger KW - Transcription, Genetic AB -

The white-apricot (wa) allele differs from the wild-type white gene by the presence of the retrovirus-like transposable element copia within the transcription unit. Most RNAs derived from wa have 3' termini within this insertion, and only small amounts of structurally normal RNA are produced. The activity of wa is reduced in trans by a semidominant mutation in the gene Enhancer-of-white-apricot (E(wa). Flies that are wa and heterozygous for the enhancer have eyes which are much lighter than the orange-yellow of wa alone while E(wa) homozygotes have white eyes. This semidominant effect on pigmentation is correlated with a corresponding decrease in white RNA having wild type structure, and flies homozygous for E(wa) have increased levels of aberrant RNAs. Three reverant alleles of E(wa) generated by reversion of the dominant enhancer phenotype with gamma radiation are noncomplementing recessive lethals, with death occurring during the larval stage. The effects on wa eye pigmentation of varying doses of the original E(wa) allele, the wild type allele, and the revertant alleles suggest that the original E(wa) allele produces a product that interferes with the activity of the wild type gene and that the revertants are null alleles. We propose that the E(wa) gene product influences the activity of the downstream copia long terminal repeat in 3' end formation.

VL - 126 CP - 4 ER - TY - JOUR T1 - Structure and expression of the Drosophila melanogaster gene for the U1 small nuclear ribonucleoprotein particle 70K protein. JF - Mol Cell Biol Y1 - 1990 A1 - Mancebo, R A1 - Lo, P C A1 - Mount, S M KW - Amino Acid Sequence KW - Animals KW - Base Sequence KW - Blotting, Northern KW - Blotting, Southern KW - Cloning, Molecular KW - DNA KW - Drosophila melanogaster KW - Gene expression KW - Gene Library KW - genes KW - HUMANS KW - Molecular Sequence Data KW - Molecular Weight KW - Oligonucleotide Probes KW - Poly A KW - Ribonucleoproteins KW - Ribonucleoproteins, Small Nuclear KW - RNA KW - RNA, Messenger KW - Sequence Homology, Nucleic Acid KW - Xenopus AB -

A genomic clone encoding the Drosophila U1 small nuclear ribonucleoprotein particle 70K protein was isolated by hybridization with a human U1 small nuclear ribonucleoprotein particle 70K protein cDNA. Southern blot and in situ hybridizations showed that this U1 70K gene is unique in the Drosophila genome, residing at cytological position 27D1,2. Polyadenylated transcripts of 1.9 and 3.1 kilobases were observed. While the 1.9-kilobase mRNA is always more abundant, the ratio of these two transcripts is developmentally regulated. Analysis of cDNA and genomic sequences indicated that these two RNAs encode an identical protein with a predicted molecular weight of 52,879. Comparison of the U1 70K proteins predicted from Drosophila, human, and Xenopus cDNAs revealed 68% amino acid identity in the most amino-terminal 214 amino acids, which include a sequence motif common to many proteins which bind RNA. The carboxy-terminal half is less well conserved but is highly charged and contains distinctive arginine-rich regions in all three species. These arginine-rich regions contain stretches of arginine-serine dipeptides like those found in transformer, transformer-2, and suppressor-of-white-apricot proteins, all of which have been identified as regulators of mRNA splicing in Drosophila melanogaster.

VL - 10 CP - 6 ER - TY - JOUR T1 - Lessons from mutant globins. JF - Nature Y1 - 1983 A1 - Mount, S A1 - Steitz, J KW - Globins KW - HUMANS KW - Mutation KW - RNA, Messenger KW - Thalassemia KW - Transcription, Genetic VL - 303 CP - 5916 ER - TY - JOUR T1 - Splicing of messenger RNA precursors is inhibited by antisera to small nuclear ribonucleoprotein. JF - Cell Y1 - 1983 A1 - Padgett, R A A1 - Mount, S M A1 - Steitz, J A A1 - Sharp, P A KW - Adenoviruses, Human KW - Antigens KW - Autoantigens KW - Base Sequence KW - Cell Extracts KW - HeLa Cells KW - HUMANS KW - Immune Sera KW - Nucleic Acid Precursors KW - Ribonucleoproteins KW - Ribonucleoproteins, Small Nuclear KW - RNA KW - RNA Precursors KW - RNA Splicing KW - RNA, Messenger KW - RNA, Small Cytoplasmic KW - RNA, Viral KW - Transcription, Genetic AB -

A mouse monoclonal antibody and human autoimmune sera directed against various classes of small ribonucleoprotein particles have been tested for inhibition of mRNA splicing in a soluble in vitro system. The splicing of the first and second leader exons of adenovirus late RNA was inhibited only by those sera that reacted with U1 RNP. Both U1 RNP-specific human autoimmune serum and sera directed against the Sm class of small nuclear RNPs, including a mouse monoclonal antibody, specifically inhibited splicing. Antisera specific for U2 RNP had no effect on splicing nor did antisera specific for the La or Ro class of small RNPs. These results suggest that U1 RNP is essential for the splicing of mRNA precursors.

VL - 35 CP - 1 ER -