Biomedical subjects
Publications and source records attributed to S Sakiyama.
Left postpneumonectomy syndrome was managed by injection of sulfur hexafluoride (SF6) into the pleural space. This measure permitted irradiation of a contralateral, second primary lung cancer without resulting pulmonary fibrosis. Such use of SF6 may be an option for prophylaxis against postpneumonectomy syndrome.
We have isolated a complementary DNA (cDNA) clone, termed N14, from a cDNA library derived from normal rat fibroblast 3Y1 cells using a differential screening procedure. N14 cDNA was 1115 nucleotides in length and contained an open reading frame of 172 amino acid residues. The expression of N14 gene was significantly increased in Rous sarcoma virus-transformed 3Y1 cells (SR-3Y1) compared with that in parental 3Y1 cells. The high level of N14 gene expression was reduced by treatment with herbimycin A, indicating that the expression was dependent upon the activity of pp60v-src tyrosine kinase. A homology search revealed that the nucleotide sequence of N14 cDNA was nearly identical to that of the rat nonsarcomeric myosin regulatory light chain cDNA (RLC-B), with the exception of a 250-nucleotide insertion which is present between C at position +483 and G at position +484 in the RLC-B cDNA. Southern blot analysis indicated that N14 gene was present as a single copy in the rat genome. Therefore, these two mRNAs might be generated through the alternative splicing mechanism. However, a RNase protection assay revealed that RLC-B mRNA was not expressed in SR-3Y1 cells. In addition, the amount of N14 mRNA was also increased in other types of transformed cells, including v-mos-, simian virus 40-, and v-Ha-ras-transformed 3Y1 cells.
A cDNA clone, termed N02, was isolated from a rat 3Y1 cDNA library using a differential screening procedure. The amount of N02 mRNA was increased in 3Y1 cells transformed with the Schmidt-Ruppin strain of Rous sarcoma virus (SR-3Y1) compared with that in 3Y1 cells. Sequence analysis revealed that N02 cDNA encodes a p36 calpactin I heavy chain. In addition, the amount of a p11 calpactin I light-chain mRNA was also increased in v-src-transformed rat culture cells. The expression of both p36 and p11 genes was also induced in several sets of transformed cells, including v-H-ras, v-mos- or SV40-transformed 3Y1 cells. As the expression of p36 and p11 genes was increased in transformed cells irrespective of the nature of oncogene products, overexpression of p36 and p11 genes might be involved in the key step of cellular transformation.
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By a differential screening procedure, we have obtained several cDNAs the expression of which was down-regulated in v-src-transformed 3Y1 cells compared to parental 3Y1 cells. One of these cDNAs, termed N26, was extensively analyzed. Sequence analysis revealed that N26 cDNA was 3,095 nucleotides in length and contained an open reading frame of 665 amino acid residues. Based on an homology search at the nucleotide level, it was postulated that N26 gene encodes lamin A. The expression of the N26 gene was not suppressed in other types of transformed cells, such as v-mos-, v-ras- and SV40-transformed 3Y1 cells.
We examined loss of heterozygosity in 49 adenocarcinomas and 18 squamous cell carcinomas of the lung with 19 RFLP markers on the short arm of chromosome 3. Although no interstitial deletions were observed in any squamous cell carcinomas, interstitial or partial deletions were detected in 23 adenocarcinomas. Identification of two common regions of deletion in adenocarcinomas, at 3p21.3 and 3p14.1-21.1, suggested the presence of at least two tumor suppressor genes on 3p within the same regions commonly deleted in renal cell carcinomas. Correlation between the frequency of loss of heterozygosity on 3p and histopathological grade of adenocarcinoma also was observed. These results imply an etiological difference between two major types of non-small cell lung cancers, adenocarcinoma and squamous cell carcinoma.
H2O2, like other oxidants, is known to act as a mitogen at low concentrations in resting Balb/3T3 or mouse epidermal JB6 cells. We described previously that H2O2 induces some early response genes in Balb/3T3 cells. We extended these observations using another cell line, MC3T3 (mouse osteoblastic) cells by examination of transcriptional activity of these genes and by using inhibitors of protein kinases. H2O2 increased the expressions of c-fos, c-jun, egr-1 and JE genes which are known to be early response genes and are induced by mitogenic stimuli in many types of cells. Exogenous addition of H2O2 increased the mRNA levels of these genes, the kinetics of increase being similar to those of their inductions by a phorbol ester or serum. Nuclear run-on transcription showed that this induction occurred at the transcriptional level. H2O2 at 0.1-0.2 mM induced maximal expressions of c-fos and c-jun, whereas 0.3 mM H2O2 was required for induction of stress-induced heme oxygenase mRNA. The inductions of c-fos and c-jun were inhibited by 50 microM H7, a protein kinase inhibitor that is relatively specific for protein kinase C, but were not affected by H9, relatively specific for cAMP-dependent protein kinase. In cells pretreated with 12-O-tetradecanoylphorbol 13-acetate, however, in which protein kinase was supposed to be downregulated, H2O2 induced c-fos and heme oxygenase as efficiently as in untreated cells. H2O2 did not increase the phosphorylation of p80 protein, which is known to be a substrate for protein kinase C. Thus, H2O2 seemed to induce c-fos and c-jun by activating protein kinases distinct from protein kinase C. Activity of the chloramphenicol acetyltransferase gene under control of the serum-response element of human c-fos genes was increased by H2O2 treatment, whereas that under control of cAMP-response element was not affected. These results indicate that the inductions by H2O2 of c-fos and possibly other early response genes are mediated through activation of the serum-response element in their enhancer.
Subcellular localisation of Ha-ras gene products (p21) and cathepsin L was investigated by immunocytochemical studies. Western blotting analysis by using v-Ha-ras p21 deletion-insertion mutants indicated that NCC-RAS-001 and -004 monoclonal antibodies recognize epitopes within amino acids 126-140 and 146-165, respectively, of Ha-ras p21. Indirect immunofluorescent studies using these antibodies showed that ras p21 is distributed in patch-shaped structures in the cytoplasm. Cathepsin L whose activity is effectively inhibited by p21s in vitro was found in the regions where p21s are concentrated. These p21-concentrated regions may be derived from endosome-like vesicles because they are also labeled with Lucifer Yellow. The co-localization of p21 and cathepsin L in cytoplasmic vesicles was also confirmed by electron microscopic immunocytochemistry.
A cDNA clone for mouse fibroblast tropomyosin (TM) 5 was obtained from a cDNA library using human TM pseudogene as a probe. Sequence analysis of the clone revealed that the deduced amino acid sequence is different only at the 4th position from the human counterpart and that both the 5' and 3' untranslated regions are highly conserved.
The activated first component of human complement, C1-s, was shown to cleave type I and II collagen and gelatin. The proteolytic activity was heat labile and was inhibited by a monoclonal antibody (M241) which recognized light chain of active human C1-s or by a serine protease inhibitor, DFP, but not by a chelating agent.
In situ hybridization of mRNAs for beta- and gamma-cytoplasmic non-muscle actin in the mouse central nervous system revealed their differential expression correlating with the developmental stages. Most intense expression of both isoactin mRNAs at the specific postnatal developmental stage was observed in pyramidal cells of cerebral cortex. Purkinje cells of the cerebellar cortex and facial motor neurons.
The expression of cytoskeletal isoactin genes in NIH 3T3 and L cells was studied by in situ hybridization. Anti-sense RNA probes specific for beta- and gamma-actin were prepared by in vitro transcription of the 3'-untranslated regions of each cDNA which diverge in an isoactin-specific manner. Both NIH 3T3 and L cells showed a higher expression of beta- and gamma-actin mRNAs in a growing state than in a stationary one. Among these changes, the suppression of gamma-actin mRNA in L cells was most prominent and that of beta-actin in 3T3 cells was least profound.
We have recently found that ras oncogene product (p21) inhibits cysteine proteinases. Because p21 transforms NIH3T3 cells and also induces differentiation of PC12 pheochromocytoma cells, several potent cysteine proteinase inhibitors have been tested for whether they show similar biological activities. The saturation density of NIH3T3 cells was increased by repeated treatment with cysteine proteinase-specific inhibitors such as N-acetyl-leucyl-leucyl-norleucinal (ALLN), N-acetyl-leucyl-leucyl-methioninal (ALLM), E-64 and chicken egg white cystatin. Furthermore, some transformed foci appeared a few weeks after the onset of the treatment. ALLN and ALLM were also able to induce neurite outgrowth of PC12 cells. Taken together, the cysteine proteinase-specific inhibitory activity of p21 may be important for its biological activities.
We have isolated several gamma-actin-related genes from a mouse genomic library. One of these has been shown to be a gamma-actin processed pseudogene (Tokunga, K., Yoda, K. and Sakiyama, S. (1985) Nucleic Acids Res. 13, 3031-3042). Here, we report the structure of another pseudogene (pMA131). pMA131 contained the sequences corresponding to the carboxyl half of a cytoskeletal actin in which random point mutations as well as insertion and deletion events took place. This region was flanked at its 5' end by the sequences related to mouse repetitive sequences, including the MIF-1 family, and was interrupted by the sequence homologous to the R family which is also a mouse repetitive sequence. The coding region was followed by the sequence corresponding to 3' untranslated region of gamma-actin mRNA.
We cloned a partial cDNA which includes an open reading frame of 459 bp long from a mouse fibroblast cDNA library. The deduced amino-acid sequence showed a partial homology with several calcium-binding proteins. The clone possibly encodes a novel calcium-binding protein whose domain adopts the E-F hand structure.
A novel calcium-dependent serine proteinase (CASP) secreted from malignant hamster embryo fibroblast Ni 12C2 degrades extracellular matrix proteins. A complementary DNA encoding CASP has been isolated with the use of oligonucleotide probes synthesized based on partial amino acid sequences of CASP. The complete amino acid sequences of CASP revealed that it has a active site at the C-terminal side. Glu rich and proEGF homologous sites are found at the N-terminal site suggesting that it is structurally similar to blood coagulation factors such as IX, X and an anticoagulation factor, protein C.
A novel serine proteinase was purified from the conditioned medium of malignant hamster embryo fibroblasts, Nil2C2. The molecular weight of the purified enzyme was estimated to be 88,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis under non-reducing conditions. The enzyme was split into two subunits (Mr 66,000 and 33,000) with a reducing agent. The enzyme hydrolyzed not only synthetic peptides which are susceptible to trypsin digestion but also extracellular matrix proteins such as type I and IV collagen, fibronectin and gelatin. For the digestion of these proteins, Ca2+ at millimolar concentrations was essential but Ca2+ or chelators did not affect the esterase activity for synthetic peptides. The proteolytic activity was inhibited by diisopropyl fluorophosphate (DFP) and also by phenylmethylsulfonyl fluoride. DFP was shown to bind to the 33 kDa subunit, indicating that the catalytic machinery of the enzyme is located in this subunit.
In-situ hybridization experiments have been performed using isoactin (beta and gamma)-specific riboprobes in various tissues of the rat and mouse. Distribution of the grains of actin mRNAs for both beta and gamma types was similar throughout sections of the rat testis. Although both mRNAs were evenly distributed in the seminiferous tubule, extremely heavy labeling was observed in about 10% of the seminiferous tubules that could be identified as stage XII of spermatogenesis. At high magnification, grains of the mRNA were found in the cytoplasm of elongating spermatids and in the Sertoli cell cytoplasm at the adluminal side. Much higher density of the grains of mRNA was observed in the neck region of the spermatids at stage XII. Thus, the dense distribution of cytoskeletal actin mRNAs is stage-specific in the tubule during spermatogenesis in the rat. The high expression of both beta and gamma actin mRNAs was also observed in the epithelial cells of the intestinal crypts.