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Stefan Maas

Publications and source records attributed to Stefan Maas.

9 recordsLinked to original sources
PubMed2006

A-to-I RNA editing and human disease.

The post-transcriptional modification of mammalian transcripts by A-to-I RNA editing has been recognized as an important mechanism for the generation of molecular diversity and also regulates protein function through recoding of genomic information. As the molecular players of editing are characterized and an increasing number of genes become identified that are subject to A-to-I modification, the potential impact of editing on the etiology or progression of human diseases is realized. Here we review the recent knowledge on where disturbances in A-to-I RNA editing have been correlated with human disease phenotypes.

Adenosine↗
PubMed2005

Modulation of ADAR1 editing activity by Z-RNA in vitro.

RNA editing by A-to-I modification has been recognized as an important molecular mechanism for generating RNA and protein diversity. In mammals, it is mediated by a family of adenosine deaminases that act on RNAs (ADARs). The large version of the editing enzyme ADAR1 (ADAR1-L), expressed from an interferon-responsible promoter, has a Z-DNA/Z-RNA binding domain at its N-terminus. We have tested the in vitro ability of the enzyme to act on a 50 bp segment of dsRNA with or without a Z-RNA forming nucleotide sequence. A-to-I editing efficiency is markedly enhanced in presence of the sequence favoring Z-RNA. In addition, an alteration in the pattern of modification along the RNA duplex becomes evident as reaction times decrease. These results suggest that the local conformation of dsRNA molecules might be an important feature for target selectivity by ADAR1 and other proteins with Z-RNA binding domains.

Adenosine Deaminase↗
PubMed2005

The crystal structure of the Zbeta domain of the RNA-editing enzyme ADAR1 reveals distinct conserved surfaces among Z-domains.

The Zalpha domains represent a growing subfamily of the winged helix-turn-helix (HTH) domain family whose members share a remarkable ability to bind specifically to Z-DNA and/or Z-RNA. They have been found exclusively in proteins involved in interferon response and, while their importance in determining pox viral pathogenicity has been demonstrated, their actual target and biological role remain obscure. Cellular proteins containing Zalpha domains bear a second homologous domain termed Zbeta, which appears to lack the ability to bind left-handed nucleic acids. Here, we present the crystal structure of the Zbeta domain from the human double-stranded RNA adenosine deaminase ADAR1 at 0.97 A, determined by single isomorphous replacement including anomalous scattering. Zbeta maintains a winged-HTH fold with the addition of a C-terminal helix. Mapping of the Zbeta conservation profile on the Zbeta surface reveals a new conserved surface formed partly by the terminal helix 4, involved in metal binding and dimerization and absent from Zalpha domains. Our results show how two domains similar in fold may have evolved into different functional entities even in the context of the same protein.

Adenosine Deaminase↗
PubMed2004

Widespread A-to-I RNA editing of Alu-containing mRNAs in the human transcriptome.

RNA editing by adenosine deamination generates RNA and protein diversity through the posttranscriptional modification of single nucleotides in RNA sequences. Few mammalian A-to-I edited genes have been identified despite evidence that many more should exist. Here we identify intramolecular pairs of Alu elements as a major target for editing in the human transcriptome. An experimental demonstration in 43 genes was extended by a broader computational analysis of more than 100,000 human mRNAs. We find that 1,445 human mRNAs (1.4%) are subject to RNA editing at more than 14,500 sites, and our data further suggest that the vast majority of pre-mRNAs (greater than 85%) are targeted in introns by the editing machinery. The editing levels of Alu-containing mRNAs correlate with distance and homology between inverted repeats and vary in different tissues. Alu-mediated RNA duplexes targeted by RNA editing are formed intramolecularly, whereas editing due to intermolecular base-pairing appears to be negligible. We present evidence that these editing events can lead to the posttranscriptional creation or elimination of splice signals affecting alternatively spliced Alu-derived exons. The analysis suggests that modification of repetitive elements is a predominant activity for RNA editing with significant implications for cellular gene expression.

5' Untranslated Regions↗
PubMed2004

RNA editing of a miRNA precursor.

Micro RNAs comprise a large family of small, functional RNAs with important roles in the regulation of protein coding genes in animals and plants. Here we show that human and mouse miRNA22 precursor molecules are subject to posttranscriptional modification by A-to-I RNA editing in vivo. The observed editing events are predicted to have significant implications for the biogenesis and function of miRNA22 and might point toward a more general role for RNA editing in the regulation of miRNA gene expression.

Animals↗
PubMed2003

New potential regulators of uterine leiomyomata from DNA arrays: the ionotropic glutamate receptor GluR2.

In the post-Genome era, new concepts emerge about the growth regulation of uterine leiomyomata. Screening of leiomyoma and myometrial tissues with DNA arrays revealed numerous genes up-regulated in leiomyomata that were not known to be expressed in the human uterus. GluR2, a subunit of a ligand-gated cation channel, is up-regulated in leiomyomata relative to myometrium by 15- to 30-fold at the protein and mRNA level and is localized in endothelial cells. GluR2 pre-mRNA in leiomyoma and myometrial tissues is nearly 100% edited at the Q/R site, indicative of low Ca(2+) permeability of the ion channels. In spontaneous leiomyomata in women or leiomyomata induced in the guinea pig model, there is a likely synergism linking increased production of estradiol and all-trans retinoic acid with up-regulation of nuclear receptor PPARgamma and RXRalpha proteins to support tumor growth. GluR2 might be coupled to this synergism directly or via interleukin-17B, kinesin KIF5 or related genes also up-regulated in leiomyomata. GluR antagonists should be tested as inhibitors of leiomyoma growth.

Female↗
PubMed2002

Surgical decompression in traumatic optic neuropathy.

BACKGROUND: The management of traumatic optic neuropathy remains controversial. This retrospective study presents the results of 19 cases of indirect optic neuropathy where surgical decompression represented the primary mode of treatment. METHODS: Nineteen patients (20 optic nerves) with traumatic optic neuropathy underwent primary surgical decompression. The surgery was performed using the transethmoidal technique. RESULTS: The extent of bony optic canal injury documented during surgery indicated that this had been underestimated in this series by CT findings. Vision improved in eight patients, five of whom had had no light perception preoperatively. CONCLUSION: Primary surgical decompression of the optic nerve within 48 h of injury produces beneficial results. Testing of visual acuity 6 weeks after surgery does not serve as a reliable predictor of final outcome.

Adolescent↗