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

Two distinct leukemia syndromes are associated with abnormalities of chromosome band 8p11. First, a myeloproliferative disorder with features characteristic of both chronic myeloid leukemia and non-Hodgkin's lymphoma and second, an acute myeloid leukemia (AML) with French-American-British (FAB) M4/5 morphology and prominent erythrophagocytosis. The two syndromes are exemplified by a t(8;13)(p11;q12) and a t(8;16)(p11;p13), respectively, but cytogenetic variants of both have been described. Recently, the t(8;16) has been cloned and shown to fuse the MOZ gene at 8p11 to the CBP gene at 16p13. We have used fluorescence in situ hybridization (FISH), Southern blotting, and reverse transcriptase-polymerase chain reaction (RT-PCR) to refine the 8p11 breakpoint in three cases with t(8;13)(p11;q12) and in a single case of AML-M5 with a clinical picture apparently identical to that found in patients with a t(8;16), but characterized by an inv(8)(p11q13). FISH analysis was performed with several 8p11 CEPH yeast artificial chromosome (YAC) clones. YAC 782H11 was centromeric to the one case with t(8;13) tested, but was telomeric to the inv(8). YAC 847B12 was telomeric to both the t(8;13) and the inv(8), whereas YAC 829D12 was centromeric to the t(8;13), but split by the inv(8). Southern blotting and PCR of YAC 829D12 showed that it contained the MOZ gene. A 900-bp MOZ fragment encompassing the published t(8;16) breakpoint was amplified by PCR from normal peripheral blood leukocyte cDNA and used to probe Southern blots of patient DNA. A rearrangement was detected in the case with inv(8), but not in any of the three cases with t(8;13). Southern blotting with a CBP probe and RT-PCR with MOZ and CBP primers suggested that the inv(8) does not result in a cryptic MOZ-CBP fusion. It is likely, therefore, that MOZ is fused to a novel gene at 8q13 in this case. We conclude that the t(8;13) breakpoint is flanked by YACs 782H11 and 847B12 and is at least 1 Mb telomeric to MOZ. MOZ is involved, however, in a new variant of the t(8;16).
 ...
PMID:Abnormalities of chromosome band 8p11 in leukemia: two clinical syndromes can be distinguished on the basis of MOZ involvement. 937 94

Acute promyelocytic leukemia (APL) is typified by the reciprocal translocation, t(15; 17)(q22; q21), leading to the formation of PML-RARalpha and RARalpha-PML fusion genes. We have characterized 7 cases of morphologic APL found to lack the t(15; 17) on conventional cytogenetic assessment. In 6 of 7 cases, cryptic PML-RARalpha rearrangements were identified by reverse transcriptase-polymerase chain reaction and fluorescent in situ hybridization (FISH); whereas, in the remaining patient, APL was associated with the variant translocation, t(11; 17)(q23; q12-21), leading to the formation of PLZF-RARalpha and RARalpha-PLZF fusion genes. In each of the cases with cryptic PML-RARalpha rearrangements, PML-RARalpha transcripts were detected in the absence of RARalpha-PML, consistent with the concept that PML-RARalpha is the critical oncogenic fusion protein. In 4 of these cases with evaluable metaphase spreads, the occurrence of a nonreciprocal translocation was confirmed by FISH with sole formation of the PML-RARalpha fusion gene; in 3 cases with morphologically normal chromosomes 15 and 17, RARalpha was inserted into PML on 15q, whereas in the remaining patient the PML-RARalpha fusion arose due to insertion of 15q-derived material including PML into RARalpha on 17q. Immunofluorescence studies were performed using antibodies raised against PML and PIC 1, a ubiquitin-homology domain protein previously identified as an interaction partner of PML. In acute myeloid leukemia (AML) of subtypes other than M3, PIC 1 was localized to the nuclear membrane and colocalized with PML within discrete nuclear bodies. In APL cases with cryptic PML-RARalpha rearrangements, the characteristic microparticulate pattern of PML staining was detected with partial colocalization with PIC 1, indicative of disruption of the nuclear bodies; whereas in t(11; 17)-associated APL, PML and PIC 1 remained colocalized within discrete nuclear bodies, as observed in non-APL cases. Although deregulation of the putative growth suppressor PML and delocalization of other nuclear body constituents have been advocated to play a key role in the development of t(15; 17)-associated APL, the present study shows that disruption of PML nuclear bodies per se is not a prerequisite for the pathogenesis of APL.
 ...
PMID:Characterization of cryptic rearrangements and variant translocations in acute promyelocytic leukemia. 938 4

The nonstructural protein-2 (NS2) of canine parvovirus (CPV) is produced from the left-hand open reading frame of the viral genome and contains 87 amino-terminal amino acids in common with nonstructural protein 1 (NS1) joined to 78 amino acids from an alternative open reading frame. In the minute virus of mice parvovirus NS2 plays a role in controlling capsid protein assembly and translation in a host-specific manner. The predicted NS2 of CPV is divergent from the proteins of the rodent parvoviruses, and the protein and its functions have not been described. We characterized the large and the small splices of CPV using reverse transcriptase-PCR, NS2 was identified using anti-peptide antibodies against the predicted C-terminal sequence and also by expressing the protein from a plasmid vector. The protein could be detected at low levels in the nucleus and the cytoplasm of a proportion of CPV-infected cells, as well as in cells transfected with the expression plasmid. Virus genomes were prepared with mutations in the splice donor or acceptor sites of the NS2-specific intron or with three different termination codons in the NS2-unique exon. Both splice donor and acceptor mutations resulted in the use of previously cryptic splice sites, and the virus containing the splice donor mutation replicated inefficiently. However, the other four mutant viruses were all viable and replicated efficiently in cat and dog cells, and two mutant viruses that were tested appeared to assemble their capsids in the same manner as did the wildtype. After inoculation of dogs an NS2 mutant virus with a termination codon in the NS2-unique exon replicated to titers similar to those seen for wildtype CPV in several tissues examined.
 ...
PMID:Nonstructural protein-2 and the replication of canine parvovirus. 945 1

Patients with generalized atrophic benign epidermolysis bullosa often show decreased expression of type XVII collagen, a transmembrane hemidesmosomal protein encoded by COL17A1. This report documents a novel splice-site mutation in COL17A1 in a patient with generalized atrophic benign epidermolysis bullosa, and applies a new methodology to define and characterize the resulting mRNA splice variants. Mutational analysis of COL17A1 identified a maternally inherited G-to-T transversion at the -1 position of exon 32. This acceptor splice-site mutation led to the formation of aberrant transcripts present at extremely low levels. Based on our recent finding that cycloheximide stabilized mutant COL17A1 transcripts in keratinocytes homozygous for a frameshift mutation, the effects of the splice-site mutation on splicing of COL17A1 transcripts were determined using reverse transcriptase polymerase chain reaction of total RNA from keratinocytes incubated for 2.5 h in the presence or absence of 10 microg cycloheximide per ml. Using this approach, an abnormally spliced transcript was identified that contains an extra 264 bases upstream from exon 32, resulting in a premature termination codon 27 bp downstream from the cryptic splice site. Three other splice variants, including one derived from the skipping of exon 32, were also identified. These results indicate the usefulness of cycloheximide treatment in evaluating the abnormal processing of mRNA due to splice-site mutations, because: (i) aberrant splicing often generates a premature termination codon, (ii) transcripts with premature termination codons can occur at low or undetectable levels due to nonsense-mediated mRNA decay, and (iii) the levels of these transcripts can be increased by cycloheximide.
 ...
PMID:Cycloheximide facilitates the identification of aberrant transcripts resulting from a novel splice-site mutation in COL17A1 in a patient with generalized atrophic benign epidermolysis bullosa. 945 13

Carnitine palmitoyltransferase I (CPT-I) catalyses the rate-determining step in mitochondrial fatty acid beta-oxidation. The enzyme has two cognate structural genes that are preferentially expressed in liver (alpha) or fat and muscle (beta). We hypothesized the existence of additional isoforms in heart to account for unique kinetic characteristics of enzyme activity in this tissue. Hybridization and PCR screening of a human cardiac cDNA library revealed the expression of two novel CPT-I isoforms generated by alternative splicing of the CPT-Ibeta transcript, in addition to the beta and alpha cDNA species previously described. Ribonuclease protection and reverse transcriptase-mediated PCR assays confirmed the presence of mRNA species of each splicing variant in heart, skeletal muscle and liver, with differing relative concentrations in the tissues. The novel splicing variants omit exons or utilize a cryptic splice donor site within an exon. Deduced polypeptide sequences of the novel enzymes include omissions in the region of putative membrane-spanning and malonyl-CoA regulatory domains compared with the previously described CPT-Is, implying that the encoded enzymes will exhibit unique features with respect to outer mitochondrial membrane topology and response to physiological and pharmacological inhibitors.
 ...
PMID:Expression of novel isoforms of carnitine palmitoyltransferase I (CPT-1) generated by alternative splicing of the CPT-ibeta gene. 969 24

Dermatofibrosarcoma protuberans (DP), an infiltrative skin tumor of intermediate malignancy, presents specific cytogenetic features such as reciprocal translocations t(17;22)(q22;q13.1) or, more often, supernumerary ring chromosomes derived from t(17;22). Different translocations, including t(2;17) and t(X;7), have also been described. We have shown previously that both r(17;22) and t(17;22) present the same molecular rearrangement fusing the COL1A1 gene on chromosome 17 and the PDGFB gene on chromosome 22. Out of our series of 16 DPs, we detected an extra ring chromosome in tumor T96-1175, which juxtaposed sequences from chromosomes 4 and 17. As shown by fluorescence in situ hybridization (FISH) using chromosome painting and alpha-satellite probes, T96-1175 apparently lacked chromosome 22 material in the ring. However, involvement of chromosome 22 through a rearrangement of PDGFB was shown by Southern blotting, reverse transcriptase-polymerase chain reaction (RT-PCR), and FISH. This study demonstrates that a cryptic molecular rearrangement between chromosomes 17 and 22 occurred in addition to the recombination of chromosomes 4 and 17 initially identified by FISH. Assessment for cryptic molecular events should be performed in other variant DP rearrangements.
 ...
PMID:COL1A1-PDGFB fusion in a ring chromosome 4 found in a dermatofibrosarcoma protuberans. 979 May 8

The human HPRT gene contains spans approximately 42,000 base pairs in genomic DNA, has a mRNA of approximately 900 bases and a protein coding sequence of 657 bases (initiation codon AUG to termination codon UAA). This coding sequence is distributed into 9 exons ranging from 18 (exon 5) to 184 (exon 3) base pairs. Intron sizes range from 170 (intron 7) to 13,075 (intron 1) base pairs. In a database of human HPRT mutations, 277 of 2224 (12.5%) mutations result in alterations in splicing of the mRNA as analyzed by both reverse transcriptase mediated production of a cDNA followed by PCR amplification and cDNA sequencing and by genomic DNA PCR amplification and sequencing. Mutations have been found in all eight 5' (donor) and 3' (acceptor) splice sequences. Mutations in the 5' splice sequences of introns 1 and 5 result in intron inclusion in the cDNA due to the use of cryptic donor splice sequences within the introns; mutations in the other six 5' sites result in simple exon exclusion. Mutations in the 3' splice sequences of introns 1, 3, 7 and 8 result in partial exon exclusion due to the use of cryptic acceptor splice sequences within the exons; mutations in the other four 3' sites result in simple exon exclusion. A base substitution in exon 3 (209G-->T) creates a new 5' (donor) splice site which results in the exclusion of 110 bases of exon 3 from the cDNA. Two base substitutions in intron 8 (IVS8-16G-->A and IVS8-3T-->G) result in the inclusion of intron 8 sequences in the cDNA due to the creation of new 3' (acceptor) splice sites. Base substitution within exons 1, 3, 4, 6 and 8 also result in splice alterations in cDNA. Those in exons 1 and 6 are at the 3' end of the exon and may directly affect splicing. Those within exons 3 and 4 may be the result of the creation of nonsense codons, while those in exon 8 cannot be explained by this mechanism. Lastly, many mutations that affect splicing of the HPRT mRNA have pleiotropic effects in that multiple cDNA products are found.
 ...
PMID:Mutations that alter RNA splicing of the human HPRT gene: a review of the spectrum. 980 51

We report on the molecular characterization of two acute myeloid leukemias (AML), one AML-M1 (patient 1) and one AML-M2 (patient 2) with t(8;21)(p21;q22) and t(8;20)(q22;p13), respectively, at diagnosis. The locations of the breakpoints, 21q22 in patient 1 and 8q22 in patient 2, prompted us to search for a cryptic t(8;21)(q22;q22) and involvement of the AML1 and ETO genes. Dual-color fluorescence in situ hybridization (FISH) using whole chromosome painting probes for chromosomes 8, 20, and 21 confirmed the conventional cytogenetic karyotypes. However, dual-color FISH using appropriate ETO and AML1 probes disclosed an insertion of AML1 into 8q22 on the derivative chromosome 8 in patient 1 and of ETO into 21q22 on one chromosome 21 in patient 2, leading to AML1-ETO fusion signals. Both cases expressed an AML1-ETO transcript, shown by reverse transcriptase polymerase chain reaction and cDNA sequencing. Creation of functional AML1-ETO fusion genes in these two simple variant t(8;21) probably occurred through complex mechanisms, combining translocation and insertion of chromosomal segments.
 ...
PMID:Simple variant t(8;21) acute myeloid leukemias harbor insertions of the AML1 or ETO genes. 988 86

Like Ig genes, TCR genes are formed by somatic rearrangements of noncontiguous genomic V, J, and C regions. Unlike Ig genes, somatic hypermutation of TCR V regions is an infrequent event. We describe the occurrence of spontaneous hypermutation in a nonproductively rearranged TCR alpha-chain gene in a clonal T cell hybridoma that had lost its productively rearranged alpha-chain. The mutating hybridoma was eventually supplanted in culture by a nonmutating variant that had restored an open reading frame in the nonproductively rearranged TCR alpha-chain through the use of cryptic splice sites in the V alpha region. Evidence is presented for the presence of cDNA reverse transcripts of the TCR alpha-chain within the hybridoma, suggesting a role for reverse transcriptase in the generation of mutations.
 ...
PMID:Alternative splicing and hypermutation of a nonproductively rearranged TCR alpha-chain in a T cell hybridoma. 991 10

NGFI-B, Nurr1 and NOR-1 constitute a distinct subfamily within the nuclear receptor superfamily. To clarify the transcriptional regulation by the NGFI-B family, we searched for other components that can bind to the NBRE response element, a known target sequence for these transcription factors. By low stringency hybridization using the DNA binding domain of NOR-1 as a probe, a C-terminal truncated Nurr1 isoform, named Nurr2, was isolated from a mouse MC3T3-E1 cell cDNA library. Nurr2 had a novel cryptic exon located upstream in the Nurr1 promoter region, and was generated by alternative splicing at exons 1, 2 and 6. The C-terminal region was encoded by frame-shifted exon 6, and so Nurr2 lacked the C-terminal sequences corresponding to the putative ligand binding domain or dimerization domain. Quantitative reverse transcriptase-PCR experiments confirmed the presence of the Nurr2 isoform in mouse, rat and human. It was, like Nurr1, highly expressed in the pituitary and the cerebral cortex. Nurr2 and Nurr1 were also concomitantly induced by forskolin in NIH3T3 cells. Functional analysis using a reporter gene, containing NBRE response elements, indicated that while the isoform was inactive by itself, it could inhibit transactivation by the members of the NGFI-B family. These results indicate that the C-terminal truncated isoform, Nurr2, may act as a negative regulator of the NGFI-B family signaling.
 ...
PMID:An isoform of Nurr1 functions as a negative inhibitor of the NGFI-B family signaling. 993 42


<< Previous 1 2 3 4 5 6 7 8 Next >>