Epigenetic risks related to assisted reproductive technologies: risk analysis and epigenetic inheritance.
(1/21)
A broad spectrum of assisted reproductive technologies has become available for couples with fertility problems. Follow-up studies of children born as a result of assisted reproduction have shown that neonatal outcome and malformation rates are not different from those of the general population, except for a low birthweight and a slight increase in chromosomal abnormalities. The safety aspect of assisted reproduction at the epigenetic level has not been well studied. Epigenetics refers to phenomena where modifications of DNA methylation and/or chromatin structure underlie changes in gene expression and phenotype characteristics. This article intends to analyse epigenetic risks related to assisted reproduction on the basis of an overview of epigenetic reprogramming events in the gamete and early embryo. Two epigenetic modifications, methylation and imprinting, are considered in more detail. The interference of in-vitro embryo culture, immature sperm cells and nuclear transfer with epigenetic reprogramming is discussed, as well as the possibility of epigenetic inheritance. (+info)
Mice and humans: chromosome engineering and its application to functional genomics.
(2/21)
Functional modeling of human genes and diseases requires suitable mammalian model organisms. For its genetic malleability, the mouse is likely to continue to play a major role in defining basic genetic traits and complex pathological disorders. Recently, gene targeting techniques have been extended towards developing new engineering strategies for generating extensive lesions and rearrangements in mouse chromosomes. While these advances create new opportunities to address similar aberrations observed in human diseases, they also open new ways of scaling-up mutagenesis projects that try to catalogue and annotate cellular functions of mammalian genes. (+info)
A prototype system for retrieval of gene functional information.
(3/21)
Microarrays allow researchers to gather data about the expression patterns of thousands of genes simultaneously. Statistical analysis can reveal which genes show statistically significant results. Making biological sense of those results requires the retrieval of functional information about the genes thus identified, typically a manual gene-by-gene retrieval of information from various on-line databases. For experiments generating thousands of genes of interest, retrieval of functional information can become a significant bottleneck. To address this issue, we are currently developing a prototype system to automate the process of retrieval of functional information from multiple on-line sources. (+info)
Portability and fidelity of RNA-repair systems.
(4/21)
Yeast tRNA ligase (Trl1) is an essential enzyme that converts cleaved tRNA half-molecules into spliced tRNAs containing a 2'-PO(4), 3'-5' phosphodiester at the splice junction. Trl1 also catalyzes splicing of HAC1 mRNA during the unfolded protein response. Trl1 performs three reactions: the 2',3'-cyclic phosphate of the proximal RNA fragment is hydrolyzed to a 3'-OH, 2'-PO(4) by a cyclic phosphodiesterase; the 5'-OH of the distal RNA fragment is phosphorylated by a GTP-dependent polynucleotide kinase; and the 3'-OH, 2'-PO(4), and 5'-PO(4) ends are then sealed by an ATP-dependent RNA ligase. The removal of the 2'-PO(4) at the splice junction is catalyzed by the essential enzyme Tpt1, which transfers the RNA 2'-PO(4) to NAD(+) to form ADP-ribose 1"-2"-cyclic phosphate. Here, we show that the bacteriophage T4 enzymes RNA ligase 1 and polynucleotide kinase/phosphatase can fulfill the tRNA and HAC1 mRNA splicing functions of yeast Trl1 in vivo and bypass the requirement for Tpt1. These results attest to the portability of RNA-repair systems, notwithstanding the significant differences in the specificities, mechanisms, and reaction intermediates of the individual yeast and T4 enzymes responsible for the RNA healing and sealing steps. We surmise that Tpt1 and its unique metabolite ADP-ribose 1"-2"-cyclic phosphate do not play essential roles in yeast independent of the tRNA-splicing reaction. Our finding that one-sixth of spliced HAC1 mRNAs in yeast cells containing the T4 RNA-repair system suffered deletion of a single nucleotide at the 3' end of the splice-donor site suggests a model whereby the yeast RNA-repair system evolved a requirement for the 2'-PO(4) for RNA ligation to suppress inappropriate RNA recombination. (+info)
A proteome-wide approach identifies sumoylated substrate proteins in yeast.
(5/21)
The ubiquitin-related protein SUMO-1 is covalently attached to proteins by SUMO-1 ligases. We have performed a proteome-wide analysis of sumoylated substrate proteins in yeast. Employing the powerful affinity purification of Protein A-Smt3 (Smt3 is the yeast homologue of SUMO-1) from yeast lysates in combination with tandem liquid chromatography mass spectrometry, we have isolated potential Smt3-carrying substrate proteins involved in DNA replication and repair, chromatin remodeling, transcription activation, Pol-I, Pol-II, and Pol-III transcription, 5' pre-mRNA capping, 3' pre-mRNA processing, proteasome function, and tubulin folding. Employing tandem affinity purifications or a rapid biochemical assay referred to as "SUMO fingerprint," we showed that several subunits of RNA polymerases I, II, and III, members of the transcription repression and chromatin remodeling machineries previously not known to be sumoylated, are modified by SUMO-1. Thus, the identification of a broad range of SUMO-1 substrate proteins is expected to lead to further insight into the regulatory aspects of sumoylation. (+info)
Poly(ADP-ribose). The most elaborate metabolite of NAD+.
(6/21)
One of the most drastic post-translational modification of proteins in eukaryotic cells is poly(ADP-ribosyl)ation, catalysed by a family enzymes termed poly(ADP-ribose) polymerases (PARPs). In the human genome, 18 different genes have been identified that all encode PARP family members. Poly(ADP-ribose) metabolism plays a role in a wide range of biological structures and processes, including DNA repair and maintenance of genomic stability, transcriptional regulation, centromere function and mitotic spindle formation, centrosomal function, structure and function of vault particles, telomere dynamics, trafficking of endosomal vesicles, apoptosis and necrosis. In this article, the most recent advances in this rapidly growing field are summarized. (+info)
Proteome analysis of Halobacterium sp. NRC-1 facilitated by the biomodule analysis tool BMSorter.
(7/21)
To better understand the extremely halophilic archaeon Halobacterium species NRC-1, we analyzed its soluble proteome by two-dimensional liquid chromatography coupled to electrospray ionization tandem mass spectrometry. A total of 888 unique proteins were identified with a ProteinProphet probability (P) between 0.9 and 1.0. To evaluate the biochemical activities of the organism, the proteomic data were subjected to a biological network analysis using our BMSorter software. This allowed us to examine the proteins expressed in different biomodules and study the interactions between pertinent biomodules. Interestingly an integrated analysis of the enzymes in the amino acid metabolism and citrate cycle networks suggested that up to eight amino acids may be converted to oxaloacetate, fumarate, or oxoglutarate in the citrate cycle for energy production. In addition, glutamate and aspartate may be interconverted from other amino acids or synthesized from citrate cycle intermediates to meet the high demand for the acidic amino acids that are required to build the highly acidic proteome of the organism. Thus this study demonstrated that proteome analysis can provide useful information and help systems analyses of organisms. (+info)
Strengthening the reporting of genetic association studies (STREGA): an extension of the STROBE statement.
(8/21)