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D K Watson

Publications and source records attributed to D K Watson.

At least 55 records · Page 3Linked to original sources
PubMed1991

D-elg, a member of the Drosophila ets gene family: sequence, expression and evolutionary comparison.

We have cloned a cDNA from the Drosophila elg gene, a new member of the ets family of genes. The D-elg gene is located at 97D on chromosome 3R and is expressed as a 2.0kb RNA in the embryos, pupae and adults, with no detectable expression in third instar larvae. D-elg expression is observed in all cells of early stage embryos, prior to transcriptional activation of the zygotic genome, and is maintained throughout embryogenesis with no regional localization. The cDNA encodes a predicted protein of 15.4kD that has an 86 amino acid sequence with 72% similarity to the carboxy terminal region of the Drosophila ets-2 gene. Comparison with all known ets genes allows us to define a minimal region required for assignment to the ets gene family.

Amino Acid Sequence↗
PubMed1991

A selective approach to operative cholangiography.

The value of operative cholangiography in the detection of common bile duct stones has been documented in a number of studies. This study suggests that operative cholangiography can be-used successfully on a more selective basis when used in conjunction with laboratory and operative criteria. One hundred and fifty patients who underwent routine cholecystectomy were retrospectively evaluated. Seventy-five percent had a normal cholangiogram and normal levels of bilirubin and alkaline phosphatase. The remaining 25% had abnormal cholangiograms as well as abnormal laboratory chemistry values. It was noted that if selective operative cholangiography had been performed only on those patients with indications for common bile duct exploration, no ductal stones would have been omitted. Based on these data, a selective approach to operative cholangiography is advocated.

Cholangiography↗
PubMed1991

The human ETS1 gene: genomic structure, promoter characterization and alternative splicing.

Genomic clones encompassing the human ETS1 gene were isolated and utilized to define its molecular organization. This gene consists of eight exons spanning over 60 kb. The 5' end of the human ETS1 gene was subcloned and characterized. S1 nuclease, primer extension and RNAase protection analyses of human mRNAs showed multiple transcription initiation sites. DNA sequence analysis indicated a high G + C content in the promoter region and the absence of either a 'TATA' box or a 'CAAT' box. Six consensus recognition sequences for the transcription factor SP1, two AP1 consensus sequences and one consensus AP2 recognition sequence were identified, as well as two GC elements with dyad symmetry. A palindromic region similar to the serum response element of the c-fos gene and two octamer consensus recognition sequences were located upstream of the promoter region. A series of promoter deletion constructs positioned upstream from the bacterial chloramphenicol acetyl transferase gene were transfected into HeLa cells and their functional promoter activity assayed. The deletion constructs identified the 5' boundary for maximum promoter activity at 486 bp upstream of the first initiation site and suggest possible positive and negative regulatory regions. Polymerase chain reaction analysis of ETS1 cDNA identified several amplified products, indicating alternative splicing. In addition to the presence of mRNA products lacking exon VII, products lacking exon IV, as well as ones lacking both exons IV and VII, were found.

Base Sequence↗
PubMed1990

ETS family of genes in leukemia and Down syndrome.

The human ETS2 and ERG genes are members of the ETS gene family, with sequence homology to the viral ets gene of the avian erythroblastosis retrovirus, E26. These genes are located on chromosome 21 and molecular genetic analysis of Down syndrome (DS) patients with partial trisomy 21 suggested that ETS2 may be a gene within the minimal DS genetic region. We have, in fact, been able to confirm the presence of the ETS2 gene dosage in triplicate occurring in occult human 21 chromosome abnormalities. It is known that ERG and ETS2 gene translocations occur in certain specific leukemias associated with defined chromosome rearrangements [e.g., t(8;21)]. Moreover, it is known that DS individuals are at greater risk for leukemic disease than their normal familial cohorts, implying that trisomy of that region of human chromosome 21 may play a role in the development of this type of neoplasia. The human ETS genes, first identified in our laboratory, are highly conserved, being found from lower organisms, like Drosophila and sea urchin, to humans. In mammals, the ETS genes are structurally distinct, located on separate chromosomes; they are transcriptionally active and differentially regulated. The ETS2 protein is phosphorylated and turns over with a half-life of approximately 20 min. After activation with the tumor promoter, TPA, the level of ETS2 elevates 5- to 20-fold. The properties of the ETS2 protein, such as nuclear localization, phosphorylation, rapid turnover, and response to protein kinase C, indicate that this protein belongs to a group of oncogene proteins thought to have regulatory functions in the nucleus. In the mouse thymus ets-1 and ets-2 are 8-10-fold higher, respectively, in the CD4+ subset than in other subsets examined, suggesting a role in T-cell development for these genes. Cells transfected with the cellular ets-2 gene, expressing higher levels of ets-2 products, showed a stimulated proliferation response, abolished their serum requirement and formed colonies in soft agar that could induce tumors in nude mice. Collectively, these data suggest that this family of genes might play a role in controlling specific steps of the signaling transduction pathway. Thus, the ETS genes, as other genes with homology to viral oncogenes, might be instrumental in regulating cellular growth and differentiation, as well as organismal development.

Animals↗
PubMed1990

Molecular and functional characterization of the promoter of ETS2, the human c-ets-2 gene.

The 5' end of the human c-ets-2 gene, ETS2, was cloned and characterized. The major transcription initiation start sites were identified, and the pertinent sequences surrounding the ETS2 promoter were determined. The promoter region of ETS2 does not possess typical "TATA" and "CAAT" elements. However, this promoter contains several repeat regions, as well as two consensus AP2 binding sites and three putative Sp1 sites. There is also a palindromic region similar to the serum response element of the c-fos gene, located 1400 base pairs (bp) upstream from the first major transcription initiation site. A G + C-rich sequence (GC element) with dyad symmetry can be seen in the ETS2 promoter, immediately following an unusually long (approximately 250-bp) polypurine-polypyrimidine tract. A series of deletion fragments from the putative promoter region were ligated in front of the bacterial chloramphenicol acetyltransferase gene and tested for activity following transfection into HeLa cells. The 5' boundary of the region needed for maximum promoter activity was found to be 159 bp upstream of the major initiation site. This region of 159 bp contains putative binding sites for transcription factors Sp1 and AP2 (one for each), the GC element, one small forward repeat, one inverted repeat, and half of the polypurine-pyrimidine tract. The promoter of ETS2 (within the polypyrimidine tract) serves to illustrate an alternative structure that may be present in genes with "TATA-less" promoters.

Base Sequence↗
PubMed1990

Molecular analysis of the ets genes and their products.

Organisms from human to Drosophila have been found to contain cellular sequences and transcripts that are homologous to the ets region of the avian retrovirus, E26. Ets-related sequences are present on at least two distinct functional loci in chickens and mammals, and have been designated ets-1 and ets-2. The E26 virus transduced sequences from the chicken ets-1 locus, which encompasses over 60 kb of DNA. The ets genes characterized so far from sea urchin and Drosophila are most closely related to the 3' end of the known ets genes. The predicted viral and avian ets proteins are very similar, except at the termini. The similarity between the predicted ets proteins so far described is discussed. The ets proteins have been identified and localized by immunoprecipitation and immunofluorescence. While the ets-1 proteins are found in the nuclear and cytoplasmic fractions, the viral gag-myb-ets protein (p135) and the ets-2 proteins are nuclear. The ets-1 and ets-2 genes are differentially regulated in different cell types, probably reflecting unique controlling elements. Because chromosomal translocations have been associated with different human leukemias, studies addressing the possible association with the ETS1 (11q23) or ETS2 (21q22.3) loci are reviewed.

Alzheimer Disease↗
PubMed1990

The human ETS-2 gene promoter: molecular dissection and nuclease hypersensitivity.

The human ETS-2 gene is a homolog of the v-ets oncogene of the E26 virus, coding for a 56 kilodalton nuclear protein. Herein we characterize the ETS-2 gene promoter, using a series of deletion constructs. Analysis of the nucleotide sequences from -3600 bp to +141 bp reveal that the region -159 bp to +141 bp is absolutely essential for maximum promoter activity. This region includes half of the lengthy polypyrimidine (CT) tract of the ETS-2 promoter, one Sp1 binding site and the GC element proximal to the initiation site. This CT tract is able to increase in an orientation independent manner, the transcription from alpha-globin promoter. Several S1 hypersensitive sites are found to be located in this promoter region, using chromatin and supercoiled DNA, in close proximity with cis regulatory elements. Our results indicate that an unusually long (approximately 250 bp) CT tract is necessary for ETS-2 transcription and this tract can also serve as a transcription activator using a heterologous promoter.

Base Sequence↗
PubMed1990

Molecular organization and differential polyadenylation sites of the human ETS2 gene.

The human ETS2 gene is a member of the ets gene family (ETS1, ETS2, ERG, ELK1 and ELK2) with amino acid similarity to the v-ets oncogene of the avian leukemia virus, E26. The ETS2 gene is composed of 10 exons, nine of which contribute to the open reading frame encoding 469 amino acids. The ETS2 gene directs the synthesis of three RNA transcripts, which differ from each other by the length of their 3' ends. This heterogeneity of 3' end is the major reason for the size differences between the transcripts, presumably reflecting utilization of three different polyadenylation signals/sites. The coding regions of all of the ETS2 RNA species are the same length and, thus, should contain the same open reading frame.

Amino Acid Sequence↗
PubMed1989

c-ets-2 protooncogene has mitogenic and oncogenic activity.

An expression vector containing the murine c-ets-2 protooncogene cDNA was introduced into NIH 3T3 cells by DNA transfection. The cells transfected with this construct showed foci of densely growing, morphologically altered cells, when grown either in low-serum (0.05%) or in serum-free medium. The c-ets-2-derived foci contained additional copies of the c-ets-2 gene, Northern blot analysis demonstrated overexpression of a c-ets-2-specific 2.5-kilobase RNA, and ets-specific antiserum recognized a 56-kDa protein. Overexpression of the c-ets-2-encoded protein stimulated cell proliferation and abolished their serum requirement. The c-ets-2 transfected cells formed colonies in semisolid medium and induced tumors in nude mice, indicating that c-ets-2 can be a transforming gene when overexpressed in these cells. This work demonstrates that a member of the c-ets gene family has transforming and mitogenic activity. In addition, the role of c-ets-2 in cell proliferation and its location in the minimal Down syndrome region on chromosome 21 implicates its involvement in the phenotypic changes associated with Down syndrome.

Animals↗
PubMed1989

Expression of human and viral ets genes in E. coli production of human ets-2-specific monoclonal antibodies.

Full-length and deletion variants of the ets proto-oncogene and v-ets oncogene of E26 virus were expressed in E. coli using the previously described expression vectors pANH1, pJL6 and pJLA16. The recombinant proteins were expressed at greater than 5% of the total cellular proteins and were characterized by Western blot analysis using ets-specific antipeptide antibodies. A number of monoclonal antibodies were raised against p35, the expressed product of the partial human ets-2 proto-oncogene construct. These monoclonal antibodies are highly specific and recognize the p56 ets-2 product from several human cell lines.

Antibodies, Monoclonal↗
PubMed1988

The Drosophila ets-2 gene: molecular structure, chromosomal localization, and developmental expression.

The cellular homologs of the ets gene from the avian erythroblastosis retrovirus E26 have been studied in chickens, humans, mice, and cats. In this report a further evolutionary step is taken by isolating and characterizing a Drosophila ets-related genomic clone. Sequence analysis of this clone has shown it to contain the 3' end of the v-ets gene, called ets-2, corresponding to the last two exons of chicken ets. The predicted amino acid sequence was found to have over 90% homology when compared to that of v-ets. This is the highest level of conservation observed for any previously characterized Drosophila oncogene homolog. Expression of the ets-2 gene occurs throughout development, but is highest during the embryonic and pupal stages. By in situ hybridization, the ets-2 chromosomal position was determined to be 58A/B which corresponds to no known phenotypic mutant. As this is a highly conserved gene, the Drosophila model system should prove useful for the determination of the ets gene function.

Alpharetrovirus↗
PubMed1988

A unique amino-terminal sequence predicted for the chicken proto-ets protein.

Avian cellular sequences homologous to the ets domain of the avian leukemia retrovirus, E26, have been characterized, and shown to contain nine discrete regions within a single locus of about 60 kb. The structure of the viral homologous and nonhomologous domains of this chicken ets-1 gene is characterized and seen to define the unique amino acid sequences of the ets protein. We have isolated and sequenced an avian ets-1 cDNA clone obtained from chicken thymus. This cDNA clone contains an open reading frame (ORF) encoding the normal cellular product of 441 amino acids. This product is significantly smaller than that encoded by the v-ets domain of the E26 transforming protein, p135, which contains 491 amino acids. The open reading frame predicted by our sequence data results in a protein calculated to be 50 kDa, which is slightly smaller than that actually observed in chicken cells. The presence of termination codons 5' to this ORF demonstrates that the cDNA characterized contains the entire coding region for the chicken ets gene.

Amino Acid Sequence↗
PubMed1988

Molecular organization of the chicken ets locus.

Chicken DNA segments homologous to the ets region from the transforming gene of avian erythroblastosis virus, E26, were molecularly cloned and shown to be almost identical to v-ets by sequence analysis. The transforming gene acids from two cell-derived sequences, myb and ets. Whereas the mammalian ets genes are present on two chromosomes, the chicken ets sequence is present as a single locus with v-ets homologous sequences found in nine regions over about 60 kb of genomic DNA. The major sequence difference between the v-ets and c-ets is found at the 3' end, resulting in different carboxy termini of p135 and the chicken proto-ets product. The chicken locus is primarily expressed in normal thymus cells as a 7.5-kb mRNA. The first two viral homologous regions are not found in this c-ets transcript or any other minor species, suggesting that they may not be true exons. Thus, the v-ets region of E26 demonstrates that two major structural differences may have occurred during the transduction of proto-ets sequences by the virus: (1) Truncation of sequences present at the 5' and 3' ends of the gene; and (2) Acquisition of noncoding proto-ets sequences into the virus. Either or both of these differences may be, in part, responsible for the oncogenic potential of this retrovirus.

Alpharetrovirus↗
PubMed1988

Mammalian ets-1 and ets-2 genes encode highly conserved proteins.

Cellular ets sequences homologous to v-ets of the avian leukemia virus E26 are highly conserved. In mammals the ets sequences are dispersed on two separate chromosomal loci, called ets-1 and ets-2. To determine the structure of these two genes and identify the open reading frames that code for the putative proteins, we have sequenced human ets-1 cDNAs and ets-2 cDNA clones obtained from both human and mouse. The human ETS1 gene is capable of encoding a protein of 441 amino acids. This protein is greater than 95% identical to the chicken c-ets-1 gene product. Thus, the human ETS1 gene is homologous to the chicken c-ets-1 gene, the protooncogene that the E26 virus transduced. Human and mouse ets-2 cDNA clones are closely related and contain open reading frames capable of encoding proteins of 469 and 468 residues, respectively. Direct comparison of these data with previously published findings indicates that ets is a family of genes whose members share distinct domains.

Amino Acid Sequence↗
PubMed1987

Molecular structure of the avian and mammalian ets genes.

The ets gene was originally identified as a second cell derived sequence transduced by the avian transforming retrovirus, E26. E26 induces erythroblastosis and myeloblastosis in chickens and transforms erythroblasts and myeloid cells in culture. From sequence analysis of the cloned provirus, the p135 transforming protein was found to be tripartite, with gag, myb and ets sequences. We have determined the nucleotide sequence of the v-ets homologous regions contained in chicken genomic clones which define nine domains. Two of these domains are not transcribed and thus do not represent functional exons. To further explore the function of the ets gene, we have begun characterization of the mammalian ets genes. Unlike the chicken gene, the mammalian ets genes are present on two chromosomes. The mammalian homologs of the 5' v-ets domain, ets-1, were mapped to chromosome 11 in man, to chromosome 9 in mouse, and to chromosome D1 in cat. The homologs of the 3' v-ets domain, ets-2, were mapped to human chromosome 21, to mouse chromosome 16, and to feline chromosome C2. The assignment of the ets-2 gene to the Down syndrome associated chromosome 21 may have interesting implications. This oncogene, ets has been connected with leukemias in chickens, and therefore might have a role in the increased frequency of leukemias in Down patients.

Amino Acid Sequence↗
PubMed1986

Amplification and rearrangement of Hu-ets-1 in leukemia and lymphoma with involvement of 11q23.

The Hu-ets-1 oncogene was found to be rearranged and amplified 30-fold in one case of acute myelomonocytic leukemia in which a homogeneously staining region occurred on 11q23; the oncogene was rearranged and amplified approximately tenfold in a case of small lymphocytic cell lymphoma with an inverted insertion that also involved band 11q23. This work suggests that Hu-ets-1 is an unusual oncogene that can help explain the common involvement of chromosome band 11q23 in various subtypes of hematopoietic malignancies.

Chromosome Aberrations↗