Evidence of redox-linked signaling for producing a giant signal complex.

Previously we showed that a thiol-reactive heavy metal, HgCl2, crosslinked multiple cell surface receptors through a ligand-independent pathway, which produced massive aggregates of phosphotyrosine (PTYR)-containing proteins beneath plasma membrane [Nakashima et al. (1994): J Immunol 152: 1064-1071]. In this study we characterized these unique aggregates at the molecular level.

Expression and tyrosine phosphorylation of phosphatidyl-inositol-3 kinase in human gastric-cancer cells - its correlation with cell-growth.

To reveal the signaling pathway leading to oncogenecity of human cancer cells, we examined the expression and tyrosine-phosphorylation of phosphatidylinositol (PI)-3 kinase in cancer cell lines. Of the 14 cell lines examined, two poorly differentiated human gastric cancer cell lines, NUGC-4 and MKN-45, which were previously found to have aberrant elevation of tyrosine phosphorylation showed elevated levels of PI-3 kinase 85-kDa subunit expression. In these cells, tyrosine-phosphorylation and overall activity of PI-3 kinase were apparently elevated, compared with normal human fibroblasts and another well differentiated gastric cancer cell line, MKN-28.

Suppression of gelatinase production with decreased invasiveness of choriocarcinoma cells by human recombinant interferon beta.

Objective: Choriocarcinoma is a highly invasive gynecologic tumor, and hematogenous metastases frequently develop. To establish a molecular basis for antiinvasion therapy of choriocarcinoma, we examined the effects of human recombinant interferons on gelatinase production and invasion by choriocarcinoma cells.

Study Design: Using five choriocarcinoma cell lines, we measured gelatinase activity by gelatin zymography.

Plasmic degradation of fibrin rapidly decreases platelet adhesion and spreading.

Plasmin cleaves fibrin at or near sites involved in platelet recognition and may modulate platelet adhesion and spreading. Using an in vitro system, we have characterized the effects of limited plasmic degradation of polymerized fibrin on platelet adhesion and spreading. As shown by scanning electron microscopy, exposure to plasmin changed the tight fibrillar fibrin surface to a less dense structure with irregular and broken fibers.

A furin-defective cell line is able to process correctly the gp160 of human immunodeficiency virus type 1.

Furin, a subtilisin-like mammalian endoprotease, is thought to be responsible for the processing of many proprotein precursors of cellular and viral origin, including gp160 of human immunodeficiency virus type 1, which share the consensus processing site motif, Arg-X-Lys/Arg-Arg, for protease recognition (for reviews, see P. J. Barr, Cell 66:1-3, 1991, and Y.

[Feasibility of DNA analysis for prognostic evaluations of colorectal cancer using touch preparations and image cytometry].

The purpose of this study is to demonstrate the applicability of DNA ploidy analysis by using touch preparations obtained from fresh and frozen tissues on the prognostic evaluations of colorectal cancer, especially the development of hepatic metastases. The specimens obtained from surgically resected colorectal carcinomas (32), and hepatic metastases (4), were lightly touched with the slide glasses. Among the 32 patients with colorectal cancers, 7 had synchronous liver metastases, and 5 metastases developed metachronously.

Assignment of disulfide bridges in the fusion glycoprotein of Sendai virus.

The mature fusion (F) glycoprotein of the paramyxovirus family consists of two disulfide-linked subunits, the N-terminal F2 and the C-terminal F1 subunits, and contains 10 cysteine residues which are highly conserved at specific positions. The high level of conservation strongly suggests that they are indeed disulfide linked and play important roles in the folding and functioning of the molecule. However, it has not even been clarified which cysteine residues link the F2 and F1 subunits.

Sperm-egg fusion in the sea urchin is blocked in Mg(2+)-free seawater.

Magnesium ions as well as calcium ions are required for successful fertilisation in sea urchins. In the absence of Mg2+ spermatozoa attached to the egg plasma membrane, their acrosomal processes passing through the vitelline envelope, but could not enter the egg cytoplasm (Sano et al., Dev.

Redox mechanism as alternative to ligand binding for receptor activation delivering disregulated cellular signals.

Cross-linking with specific ligand is a general requirement for ordered activation of cell surface receptors. In this study we demonstrated a novel pathway for disregulated receptor activation through a redox mechanism. Treatment of murine thymocytes or spleen cells with thiol-reactive HgCl2, a known inducer of autoimmune proliferative lymphocyte disorders in rodents, was found to induce tyrosine phosphorylation of several cellular proteins, which was up to 100 times as extensive as that triggered by stimulation with antireceptor antibody or mitogen.

Messenger RNA levels of five genes located at chromosome 11q13 in B-cell tumors with chromosome translocation t(11;14)(q13;q32).

To identify genes activated by chromosome translocation t(11;14)(q13;q32), mRNA levels of five genes (cyclin D1, EXP1, MB38, HST1, and INT2) at chromosome 11q13 were investigated. The cyclin D1 mRNA increased in BCL-1-rearranged B-cell tumor cell lines SP-49, NOP-2, FLAM-76, KMS-12-PE, and KMS-12-BM cells, while it was not detected in cell lines without the translocation, Raji, U266, and HEL cells. A significant amount of the MB38 mRNA was detected irrelevantly to the translocation in all of these cell lines.

Abundant but inactive-state gp140proto-trk is expressed in neuroblastomas of patients with good prognosis.

Steady-state levels of gp140proto-trk in cell lines and tumor tissues of neuroblastoma were examined by immunoblotting with anti-gp140proto-trk. The level of gp140proto-trk varied but showed good correlations with the stage of the tumor and the age of the patients at the time of diagnosis. Moreover, patients with higher expression of gp140proto-trk clearly had a far better survival rate than those with lower expression, suggesting that suppression of gp140proto-trk strongly correlates with the malignant conversion of the tumor.

Respiratory activities in relation to external glossal muscles.

In this study, the activities of the two external glossal muscles, Genioglossus (Gg) and Styloglossus (Sg), related to respiration were examined through the electromyography (EMG) in dog. During quiet breathing, no phasic respiratory activity were observed in either muscle. With hypercapnic condition induced by closed rebreathing respiratory system, both Sg and Gg showed phasic respiratory activities in respiration period.

Phosphate metabolism during muscular contraction in starved frogs (Rana catesbeiana).

1. The muscle tension and the state of high-energy phosphate metabolism during contraction of the sartorius muscle in frogs (Rana catesbeiana) starved for 1-5 months was studied by in vivo 31P-NMR spectrometry. 2.

Pathway of signal delivery to murine thymocytes triggered by co-crosslinking CD3 and Thy-1 for cellular DNA fragmentation and growth inhibition.

The signal delivery pathway triggered by crosslinking CD3 and Thy-1 together (CD3/Thy-1 crosslinkage) on murine thymocytes for cellular DNA fragmentation/growth inhibition was analyzed. The treatment of thymocytes with herbimycin A as a specific tyrosine kinase inhibitor under suboptimum conditions before the CD3/Thy-1 crosslinkage partially but preferentially inhibited the otherwise promoted tyrosine phosphorylation of p40 and p56. Evidence was then provided that acceleration of the kinase activity of p56lck was involved in the CD3/Thy-1 crosslinkage-triggered signal.

Glycyrrhizin as a promoter of the late signal transduction for interleukin-2 production by splenic lymphocytes.

Cellular and molecular mechanisms of the immunomodulatory action of glycyrrhizin (GL) were studied. We demonstrated that GL displays a unique action to prolong the duration of the T-cell receptor-mediated in vitro splenic T-lymphocyte growth response to anti-CD3 monoclonal antibody (mAb) or concanavalin A (Con A) through enhancement of interleukin-2 (IL-2) secretion and IL-2 receptor (IL-2R) expression. The augmentation by GL of IL-2 production was also found in spleen cells stimulated with A23187 plus phorbol 12-myristate 13-acetate (PMA), suggesting that GL primarily affects some post-receptor stage of the signal transduction.

Deletion mapping of chromosome 3p in human uterine cervical cancer.

Deletion mapping of chromosome 3p was performed on 47 cases of human uterine cervical cancer using 24 polymorphic DNA markers including five inter-Alu DNA markers and two NotI-boundary cosmid markers obtained in our laboratory. The most likely order of these 24 polymorphic DNA markers was determined as being cen-[D3S4, H8]-D3S693-D3S659-D3S30-D3S687-[D3S2, UR9, UR47]-J36-J17-GNAI2B-D3F15S2-D3S643- D3S32-D3S23-D3S686-H35-UR189-D3S685-D3S 11 - D3S12-THRB-D3S22-pter, based on the data from radiation hybrid mapping genetic linkage analysis and in situ hybridization. Loss of heterozygosity (LOH) at one or more loci on chromosome 3p was detected in 21 of 47 cases (45%).

Spreading of platelets on fibrin is mediated by the amino terminus of the beta chain including peptide beta 15-42.

We have investigated the adhesion and spreading of platelets on polymerized fibrin of varying structure to identify sites that mediate these interactions. Fibrin was prepared with thrombin to remove both fibrinopeptide A (FPA) and fibrinopeptide B (FPB) and with reptilase or Agkistrodon contortrix thrombin-like enzyme (ACTE) to selectively remove FPA or FPB, respectively. Residual fibrin-bound enzymes were inhibited with D-phenylalanyl-L-prolyl-L-arginyl chloromethyl ketone (PPACK).

Cross-linking of B cell receptor-related MB-1 molecule induces protein tyrosine phosphorylation in early B lineage cells.

Cross-linking of surface B cell Ag receptor (BCR) induces tyrosine phosphorylation of BCR-associated components through a receptor-mediated signal transmission pathway. B cell-specific mb-1 and B29 genes encode the alpha/beta components of the BCR-associated complex in mature sIgM+ B cells. Here, we studied the involvement of the mb-1 gene product, MB-1, in the BCR-related structure of immature B cells.

Relationship between myoglobin contents and increases in cyclic GMP produced by glyceryl trinitrate and nitric oxide in rabbit aorta, right atrium and papillary muscle.

Effects of glyceryl trinitrate (GTN) and nitric oxide (NO) on the cardiac functions and myocardial cyclic GMP (cGMP) contents were examined in comparison with those in the aorta and correlated with myoglobin (an inhibitor of soluble guanylate cyclase) contents using the preparations isolated from the reserpinized rabbit. GTN (10(-10)-10(-4) mol/l) produced a dose-dependent relaxation in the aorta. However, this compound exerted no effect on the rate of the spontaneous beat of the right atrium and the contraction of the papillary muscle.

Herbimycin A inhibits the association of p60v-src with the cytoskeletal structure and with phosphatidylinositol 3' kinase.

To search for the biochemical prerequisites for morphological transformation by p60v-src, we examined the effect of herbimycin A, a potent inhibitor of cell transformation, on chicken embryonic fibroblasts transformed by Rous sarcoma virus. A small dose of herbimycin (0.1-0.

Redox-linked ligand-independent cell surface triggering for extensive protein tyrosine phosphorylation.

Exposure of lymphocytes to 0.2-2 mM HgCl2, a thiol-reactive heavy metal, induced extensive tyrosine phosphorylation of multiple cellular proteins. The phosphorylation started as quickly as 5 s after exposure to HgCl2, and was irreversible.

p60v-src causes tyrosine phosphorylation and inactivation of the N-cadherin-catenin cell adhesion system.

Transformation of chick embryonic fibroblasts with Rous sarcoma virus strongly suppresses N-cadherin-mediated cell-cell adhesion, without inhibiting its expression. This suppression is correlated with tyrosine phosphorylation of N-cadherin and catenins, the cadherin-associated proteins, which are known to regulate cadherin function. Experiments with non-myristylation and temperature-sensitive mutants of RSV and with herbimycin A, a potent inhibitor of tyrosine kinases, suggest that both the suppression of cell adhesion and tyrosine phosphorylation of catenins are highly transformation-specific.

P-glycoprotein expression in hepatocellular carcinoma.

In hepatocellular carcinoma cell lines, the intensity of staining with the monoclonal antibody C-219 to the multidrug-resistant gene (mdr1) product P-glycoprotein and the intensity of the band at a molecular weight of 170 KDa on Western blot were associated closely with resistance to Adriamycin but not with the resistance to cis-dichlorodiamine platinum (CDDP). In clinical specimens, noncancerous liver tissue was regularly stained with this antibody on the biliary canalicular front of the hepatocyte cell membrane. In liver cancer tissue, however, regular staining as in the noncancerous regions of the liver was observed in only 16% of the patients, irregular staining was seen in only 24%, and no staining was seen at all in 60%.

Effects of sodium nitroprusside (MR7S1) and nitroglycerin on the systemic, renal, cerebral, and coronary circulation of dogs anesthetized with enflurane.

In beagle dogs anesthetized with enflurane-nitrous oxide, effects of sodium nitroprusside (SNP; MR7S1) and nitroglycerin (NTG) on hemodynamics and main organ circulation were studied to evaluate their effectiveness and safety as hypotensive agents during anesthesia. SNP (MR7S1) infusion (1-10 micrograms/kg/min) decreased arterial blood pressure in a dose-dependent manner. The hypotension was stable during the infusion.

Characterization of a Gly19-->Val mutant of ram p25, a low Mr GTP-binding protein: loss of GTP/GDP-binding activity in the mutated ram p25.

A substitution of Gly for Val at position 19, which corresponds to oncogenic Gly13-->Val mutation of ras p21, was introduced in a low Mr GTP-binding protein, ram p25. The protein was expressed in cytosolic fraction of Escherichia coli and purified by using specific antibody raised against ram p25. The mutated protein had no guanine nucleotide-binding activity although [Val13]ras p21 was reported to have.