Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Dyskeratosis congenita is an inherited syndrome characterised by mucocutaneous features, bone marrow failure, an increased risk of malignancy and other somatic abnormalities. There is a considerable range of clinical severity and in its occult form the disease may present as idiopathic aplastic anaemia. Genes responsible for X-linked, autosomal dominant and autosomal recessive forms of the disease have been identified and been found to encode products involved in telomere maintenance. Premature shortening of telomeres could account for the pathology, affecting the tissues that turn over most rapidly. However, the protein that is mutated in the X-linked disease, dyskerin, also plays a fundamental role in ribosome biogenesis, directing the pseudouridylation of ribosomal RNA using H/ACA small nucleolar RNAs as guides. Heterozygous mutations in the RNA component of telomerase (TERC) cause the autosomal dominant form of the disease through haploinsufficiency. Disease anticipation described in these families is associated with progressive telomere shortening through the generations. Heterozygous mutations in the reverse transcriptase component of telomerase (TERT) have a more variable role, often displaying incomplete penetrance and diverse clinical presentation. The autosomal recessive form of the disease is genetically heterogeneous, although one sub-type has been described in which NOP10 is mutated. This small protein is also associated with the maturation of ribosomal RNA and the telomerase complex.
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PMID:Dyskeratosis congenita: the diverse clinical presentation of mutations in the telomerase complex. 1782 70

Dyskeratosis congenita (DC) is an inherited disorder that implicates defects in the biology of telomeres, which are maintained by telomerase, a ribonucleoprotein with reverse transcriptase activity. Like all H/ACA RNAs, the H/ACA domain of nascent human telomerase RNA (hTR) forms a pre-RNP with H/ACA proteins NAF1, dyskerin, NOP10, and NHP2 in vivo. To assess the pre-RNP assembly of hTR mutants that poorly accumulate in vivo, we developed an in vitro system that uses components of human origin. Pre-RNPs were reconstituted with synthetic (32)P-labeled RNAs and (35)S-labeled proteins produced in rabbit reticulocyte lysate, and immunoprecipitations were carried out to analyze RNP formation. We show that human NAF1 cannot bind directly to the H/ACA domain of hTR, and requires the core trimer dyskerin-NOP10-NHP2 to be efficiently incorporated into the pre-RNP. This order of assembly seems common to H/ACA RNAs since it was observed with snoRNA ACA36 and scaRNA U92, which are predicted to guide pseudouridylation of 18S rRNA and U2 snRNA, respectively. However, the processing H/ACA snoRNA U17 did not conform to this rule, as NAF1 alone was able to bind it. We also provide the first evidence that DC-related mutations of hTR C408G and Delta378-451 severely impair pre-RNP assembly. Integrity of boxes H and ACA of hTR are also crucial for pre-RNP assembly, while the CAB box is dispensable. Our results offer new insights into the defects caused by some mutations located in the H/ACA domain of hTR.
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PMID:Dyskeratosis congenita mutations in the H/ACA domain of human telomerase RNA affect its assembly into a pre-RNP. 1909 16

Spinocerebellar ataxia type 2 (SCA2) and amyotrophic lateral sclerosis (ALS) are neurodegenerative disorders, caused or modified by an unstable CAG-repeat expansion in the SCA2 gene, which encodes a polyglutamine (polyQ) domain expansion in ataxin-2 (ATXN2). ATXN2 is an RNA-binding protein and interacts with the poly(A)-binding protein PABPC1, localizing to ribosomes at the rough endoplasmic reticulum. Under cell stress, ATXN2, PABPC1 and small ribosomal subunits are relocated to stress granules, where mRNAs are protected from translation and from degradation. It is unknown whether ATXN2 associates preferentially with specific mRNAs or how it modulates RNA processing. Here, we investigated the RNA profile of the liver and cerebellum from Atxn2 knockout (Atxn2 (-/-)) mice at two adult ages, employing oligonucleotide microarrays. Prominent increases were observed for Lsm12/Paip1 (>2-fold), translation modulators known as protein interactor/competitor of ATXN2 and for Plin3/Mttp (>1.3-fold), known as apolipoprotein modulators in agreement with the hepatosteatosis phenotype of the Atxn2 (-/-) mice. Consistent modest upregulations were also observed for many factors in the ribosome and the translation/secretion apparatus. Quantitative reverse transcriptase PCR in liver tissue validated >1.2-fold upregulations for the ribosomal biogenesis modulator Nop10, the ribosomal components Rps10, Rps18, Rpl14, Rpl18, Gnb2l1, the translation initiation factors Eif2s2, Eif3s6, Eif4b, Pabpc1 and the rER translocase factors Srp14, Ssr1, Sec61b. Quantitative immunoblots substantiated the increased abundance of NOP10, RPS3, RPS6, RPS10, RPS18, GNB2L1 in SDS protein fractions, and of PABPC1. In mouse embryonal fibroblasts, ATXN2 absence also enhanced phosphorylation of the ribosomal protein S6 during growth stimulation, while impairing the rate of overall protein synthesis rates, suggesting a block between the enhanced translation drive and the impaired execution. Thus, the physiological role of ATXN2 subtly modifies the abundance of cellular translation factors as well as global translation.
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PMID:Genetic ablation of ataxin-2 increases several global translation factors in their transcript abundance but decreases translation rate. 2572 94

The telomerase complex and Telosome regulate, maintenance and repair telomeres. The telomerase complex is formed by complex of protein (TERT, Dyskerin, GAR, NHP2, NOP10) and nucleic acid (TERC) that together work as a reverse transcriptase. The Telosoma comprises a network of protein (TRF2, TRF1, TIN2, RAP1, TPP1 and POT1). Furthermore, dyskeratosis congenita (DC) (ORPHA1775) is a rare disease with similar characteristics to premature aging. DC is a genetically heterogeneous disease caused by mutations in the genes that encoding for different subunits of the telomerase complex and Telosome. It is known that the telomeric DNA is susceptible to oxidative stress, and telomerase activity dependent cellular redox environment. Recently a correlation between telomerase activity and catalase activity was established, and it has suggested a role of antioxidant extranuclear telomerase. However, it is not yet clear whether there is any relationship or connection between molecular telomerase activity and cellular antioxidant defense. In this paper, by using the technology of RNA interference (siRNA) silencing DKC1, NOP10 genes of telomerase complex and TINF2 of Telosoma in HeLa cells, on cellular antioxidant capacity will be presented. It was intended to see if there is a cellular effect related to the production of oxidative stress or alteration of antioxidant systems after silencing these components involved in telomere maintenance. In this paper we have evaluated the levels of DKC1, NOP10, TINF2 levels of antioxidant enzymes (CuZnSOD, MnSOD, Catalase, Gpx1, Grx1 and Trx1) by RT- qPCR and Western blotting. We analyzed the production of reactive oxygen species by fluorimetry and also assessed the activity of the telomerase complex by Sybr Green RT- QTrap.
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PMID:Characterization of the antioxidant systems in different complementation groups of Dyskeratosis Congenita. 2646 48