Biomedical subjects
Publications and source records attributed to N Miyajima.
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By applying the protocol previously established, we isolated and sequenced full-length cDNA clones longer than 2 kb from cDNA library of human immature myeloid cell line KG-1, and the coding sequences of 40 new genes were predicted. A computer search of the sequences indicated that 29 genes contained sequences with similarities to reported genes in the GenBank/EMBL databases. Significant transmembrane domains were identified in 9 genes, 5 of which harbored multiple hydrophobic regions. Protein motifs that matched those in the PROSITE motif database were identified in 13 genes. In terms of sequence similarities and protein motifs, 5 genes were related to transcriptional factors. Repetitive sequences were found in the 3'-untranslated region of 8 genes. Northern hybridization demonstrated that the expression of 9 genes was tissue-specific, while the remaining 31 genes were expressed ubiquitously. It was also noted that 17 genes yielded different sizes of bands possibly due to either alternative splicing or alternative initiation. The chromosomal location of these genes has been determined.
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We have previously reported that a c-myc protein complex binds to the region upstream of the c-myc gene, where exist an origin of cellular DNA replication (ori) and a transcriptional enhancer. Both functions require a 21 bp long sequence, while the c-myc protein complex recognizes a 7 bp consensus therein. It was recently reported that single-stranded DNA binding proteins bound specifically to sequences that play roles in DNA replication or transcription. We examined for proteins binding to the single-stranded DNAs of the 21 bp element (myc(H-P)21). In a band shift assay with HL60 cells nuclear extract, probes of either the plus strand or the minus strand gave rise to specific signals. Mutation introduced within a short consensus (A/TCTA/TA/TT) present in both strands completely abolished binding in either case. Southwestern blotting analysis showed that proteins of molecular weight 105, 80, 50, 45, 40, 39.5 and 14 kDa bound sequence-specifically to either strand and 22 kDa to minus strand to the cognate A/TCTA/TA/TT consensus. These single-stranded DNA binding proteins were named MSSP, c-myc gene single strand binding proteins. We attempted to isolate the cDNAs encoding these proteins by screening a human cDNA library with the plus single-stranded oligonucleotide as a probe. Among several positive clones, we have characterized one, termed MSSP-1. MSSP-1 produced in E. coli as a fusion protein with GST specifically interacted with single-stranded TCTTAT (plus myc(H-P)21) and ACT-ATT (in minus myc(H-P)21), the consensus of which can be referred to as A/TCTA/TA/TT. Sequence analysis of MSSP-1 cDNA revealed that two domains thereof are homologous to the RNA binding motifs common to several ribonucleoproteins. Interestingly, the MSSP-1/GST fusion protein specifically recognized myc(H-P)21 not only in single-stranded but also in double-stranded forms. Binding properties of MSSP-1 imply its functions in DNA replication. Furthermore, when the AT stretch in the SV40 ori core was substituted by TCTTAT, MSSP-1 promoted viral DNA replication depending on the consensus sequences.
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The incidence and association with 10-year survival of amplification in five protooncogenes or transforming genes were retrospectively examined using DNAs extracted from formalin-fixed, paraffin-embedded blocks of tissues obtained from 176 consecutive patients surgically treated for primary breast carcinoma. The incidences of greater than threefold amplification of hst-1, int-2, c-erbB-2, ear-1 (one of c-erbA), and c-myc were 12, 13, 16, 10, and 4.0%, respectively. hst-1 and int-2 were almost always coamplified (21/22), while c-erbB-2 and ear-1 were frequently coamplified (18/28) with almost the same copy number. The hst-1 and int-2 pair and the c-erbB-2 and ear-1 pair, localized on chromosomes 11q13 and 17q21-22, respectively, in normal cells, were inferred to be constituents of different amplification units. Amplification of hst-1 and/or int-2 was detected preferentially in the younger age group, and was correlated with poorer prognosis in cases carrying four or more copies of the genes. Amplification of c-erbB-2 and/or ear-1 was strongly correlated with poor prognosis in all 176 patients, especially those with lymph node metastasis. Amplification of c-myc was also correlated with poor prognosis. Cox's life-table regression analysis showed that amplification of c-erbB-2 had a prognostic value, which was independent of other known prognostic factors such as lymph node status and tumor size.
Two erbA homologs, termed ear-1 and ear-7, are present in the human genome on chromosome 17. The two genes reside in the same genetic locus with overlapping exons and are transcribed from opposite DNA strands. In addition, the ear-7 mRNA is alternatively spliced to generate two protein isoforms, namely the ear71 and ear72 proteins. Nucleotide sequence analysis predicts that the ear71 protein is a human counterpart of the chicken c-erbA protein, a molecule closely related or identical to thyroid hormone receptor. Indeed, Scatchard analysis of proteins synthesized in vitro indicated very high affinity binding of T3 to the ear71 protein but not to the ear72 protein. Interestingly, the ear-1 gene product showed low, but appreciable, binding to T3, although its authentic ligand remains to be clarified.
Two v-erbA-related genes, named ear-2 and ear-3, have been identified in the human genome and characterized by cDNA cloning. These genes are predicted to encode proteins that are very similar in primary structure to receptors for steroid hormones or thyroid hormone (T3). In addition, amino acid sequences of the ear-2 and ear-3 gene products are very similar each other especially at the DNA binding domain (86% homology) and at the putative ligand binding domain (76% homology). Northern hybridization with ear DNA probes of RNAs from various tissues of a human fetus reveals that the expression of ear-2 is high in the liver whereas the expression of ear-3 is relatively ubiquitous. Hybridization analysis of DNAs from sorted chromosomes shows that the ear-2 gene is located on chromosome 19 and ear-3 on chromosome 5, indicating that the two genes are clearly different from each other.
1. We characterized several small RNAs in various tissues and strains of the silkworm, Bombyx mori by the in vitro capping and in vitro transcription. 2. Three subspecies of 7SL RNA, which is believed to be involved in protein secretion, were detected in the commercial strains. Structural differences among the three molecules were due to the nucleotide substitution at two positions or more. 3. A very AU-rich RNA, which is about 500 bases long, was always present in any tissue of Bombyx mori while 55 base RNA was only observed in a substantial amount in the fat body and culture cells. 4. These small RNAs were also observed among the in vitro transcripts of total Bombyx DNA in the cell-free extracts from the silkgland and fat body.
We analyzed for alterations of the c-erbB-2 oncogene in 35 human stomach cancers and 8 cell lines derived from human stomach cancer. Amplification of c-erbB-2 was found in approximately 40% (5/13) of the tubular adenocarcinomas of the stomach examined, including 4 of 10 fresh tumors and one of 3 cell lines, but not in other histological types of stomach cancer examined (0/30), including 25 fresh tumors and 5 cell lines. This result strongly suggests that amplification of c-erbB-2 occurs frequently in tubular carcinomas in stomach cancer. Rearrangement of c-erbB-2 was also detected in one tubular adenocarcinoma. The rearranged fragment carried the 3' half, but not the 5' sequence, of the c-erbB-2 gene. Furthermore, one of the cellular homologues of v-erbA was amplified in 3 of 4 fresh tumors carrying the amplified c-erbB-2 gene. Both c-erbB-2 and the v-erbA homologue were expressed in all the stomach cancer cell lines tested.
Transcatheter arterial chemoembolization (TAE) and hepatic arterial infusion using totally implantable reservoir were performed for the treatment of liver metastasis of colo-rectal cancers, and their therapeutic effects, side effects and complications were evaluated. Eleven cases of H1 (metastasis in one lobe only), 7 cases of H2 (a few scattered metastases in both lobes), 12 cases of H3 (numerous metastases in both lobes) were entered into the study and underwent TAE 45 times. Gel foam, Ivaron and Lipiodol were used as embolic materials in combination with chemotherapeutic agents such as mitomycin C and adriamycin. Serum CEA level was decreased less than 50% of pre-TAE level 20 out of 32 (61%). The tumor size was regressed in 25% of TAE cases which were evaluated on the basis of CT scan. Abdominal symptoms including abdominal pain, nausea and vomiting and fever, leukocytosis, elevated GOT, LDH and bilirubin level were seen after TAE therapy. Median survival of H1, H2 and H3 cases were 21 months, 8 months and 4.5 months, respectively. Another 21 cases (H1, 5 cases: H2, 3 cases: H3, 13 cases) of liver metastasis of colo-rectal cancers were treated with selective hepatic arterial infusion therapy using totally implantable reservoir. Reservoir catheters were implanted into hepatic artery via gastroduodenal artery under direct vision at laparotomy. Mitomycin C, adriamycin and fluorouracil (5-FU) were used as chemotherapeutic agents. No particular side effect such as leukopenia or liver dysfunction was noted. Median survival of H1, H2 and H3 cases treated with arterial infusion were 4 months, 9 months and 9 months, respectively. Median survival of TAE cases and arterial infusion cases was 10 and 6 months, respectively. Thus, the survival rate of cases treated with TAE was better than that of cases treated with arterial infusion.
Using a DNA probe from an avian transforming virus, NK24, that contains the fos gene and that was newly isolated and characterized (M. Nishizawa, N. Goto, and S. Kawai, J. Virol. 61:3733-3740, 1987), we cloned and sequenced the chicken c-fos gene. Results showed that this gene, like the mouse or human c-fos gene, contains four exons encoding a predicted gene product of 367 amino acids which is about 79% homologous to p55c-fos (mouse), excluding several small insertions or gaps. The predicted gene product, however, contains two nonhomologous regions, as suggested by sequence analysis of the NK24 genome. About half the identical amino acids of these gene products are encoded by different codons, and the guanine-plus-cytosine content in the third letter of each codon used in the entire chicken c-fos coding region is high (93%). The 5'-flanking region of the TATA box contains a sequence that is homologous to a putative transcriptional regulatory sequence in the mouse or human c-fos gene. The 3'-noncoding region of chicken c-fos is strikingly homologous to that of mouse or human c-fos and covers a 67-base-pair adenine-plus-thymine-rich stretch which was previously reported to be essential for an inhibitory effect on the expression of the mouse c-fos gene.
With v-yes DNA as the probe, a human cDNA library made from placental RNA was screened under relaxed conditions, and DNA clones derived from a novel genetic locus, termed lyn, were obtained. Nucleotide sequencing revealed that lyn could encode a novel tyrosine kinase that was very similar to mouse T-lymphocyte-specific tyrosine kinase p56lck and the v-yes protein as well as to the gene products of v-fgr and v-src. Northern hybridization analysis revealed that a 3.2-kilobase lyn mRNA was expressed in a variety of tissues of the human fetus. The pattern of lyn mRNA expression was different from those of related genes, such as yes and syn. Hybridization analysis of DNA from sorted chromosomes showed that the lyn gene is located on human chromosome 8 q13-qter.
Three c-yes cDNA clones were obtained from poly(A)+ RNA of human embryo fibroblasts. Sequence analysis of the clones showed that they contained inserts corresponding to nearly full-length human c-yes mRNA, which could encode a polypeptide of 543 amino acids with a relative molecular weight (Mr) of 60,801. The predicted amino acid sequence of the protein has no apparent membrane-spanning region or suspected ligand binding domain and closely resembles pp60c-src. Comparison of the sequences of c-yes and v-yes revealed that the v-yes gene contains most of the c-yes coding sequence except the region encoding its extreme carboxyl terminus. The region missing from the v-yes protein is the part that is highly conserved in cellular gene products of the protein-tyrosine kinase family.
An src/yes-related novel gene named syn (SYN in human gene nomenclature) has been identified in the human genome on chromosome 6 and characterized by molecular cloning. Nucleotide sequence analysis of cDNA clones showed that the c-syn gene could encode a protein-tyrosine kinase that is very similar in primary structure to the v-yes and human c-src proteins. A 2.8-kilobase transcript of the c-syn gene, which differs in size from those of the c-yes, c-src, and c-fgr genes, was observed in various cell types. These results show that syn is a new member of the tyrosine kinase oncogene family.
We have determined the total coding sequence of human c-yes, a non-receptor type protein-tyrosine kinase gene, and found that the c-yes gene closely resembles the c-src gene. Recently, two new genes, syn and lyn, were found to encode proteins closely related to the yes product. In addition, we also determined the partial sequence of fgr. These genes together with lck reported by two American groups have very closely related structures and are thought to compose a closely related group of non-receptor type protein-tyrosine kinases. Partial analysis of the structures of these genes indicated that they have identical splicing junctions at all sites so far examined. On the other hand, the erbB-1/EGF (epidermal growth factor) receptor gene and the erbB-2/neu gene have completely different splicing junctions from those of the above gene group even in the kinase domain, although these genes also have protein kinase activity specific for tyrosine residues and the erbB-1 and -2 genes share splicing sites. These results suggest that the genes of the group of six non-receptor type kinases and those of the erbB-1 and erbB-2 gene group are descendants evolved by duplication of two distinct ancestor genes and are members of two distinct multi-gene families. The genes coding for protein kinases may be members of a super-family including multiple distinct gene families.