Kiyoshi Nose

Effects of the protein kinase C inhibitor H-7 and calmodulin antagonist W-7 on superoxide production in growing and resting human histiocytic leukemia cells (U937)

Serum, phorbol 12,13-didecanoate (PDD) and 1-oleoyl-2-acetoy-sn-glycerol (OAG) stimulated O2- release in human histiocytic leukemia U937 cells. The kinetics of O2- release caused by PDD but not by serum or OAG in growing cells differed from those in resting cells. Both the protein kinase C inhibitor 1-(5-isoquinolinylsulfonyl) 2-methylpiperidine (H-7) and calmodulin antagonist N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) reduced the superoxide generation induced by these stimuli. H-7 inhibited the O2- release either from growing or resting cells but the effect of W-7 varied according to the growth phase. From these results, it is suggested that activation of protein kinase C and calmodulin-dependent process has an important role in O2(-)-release induced by serum, OAG and PDD, and that the mechanism for PDD-induced O2(-)-release is different in growing and resting cells.

Arrest of cultured rat liver cells in G2 phase by the treatment with dibutyryl cAMP

Abstract When rat liver cells which had been grown in a protein- and lipid-free synthetic medium were incubated in the presence of dibutyryl adenosine 3′:5′-cyclic monophosphate (But 2 cAMP) and theophylline, labeling index of cells with [ 3 H]-thymidine was decreased. Percentage of cells which had twice the amount of DNA per nucleus compared to the basic value increased during the cultivation of cells in the presence of the drugs. Mitotic index increased immediately after the removal of the drugs. From these results, it was concluded that But 2 cAMP arrested the cell cycle mainly at G2 phase.

BINDING OF FOREIGN DNA TO MOUSE SPERM MEDIATED BY ITS MHC CLASS II STRUCTURE

ABSTRACT: By means of radioimmunoassay, the expression of the major histocompatibility complex (MHC) class II molecules on murine sperm cells was clearly demonstrated as well as by our previous enzyme immunoassay (Mori T, et al. The expression of class II major histocompatibility antigen on mouse sperm and its role in fertilization. Am J Reprod Immunol. 1990; 24:9–14). The present study revealed that the site of sperm for binding foreign DNA was mediated by the complex structure of the MHC class II molecules localized at the posterior region of sperm head. This binding activity of sperm was time‐, temperature‐, and viability‐dependent and completely inhibited by the treatment of sperm cells with mouse anti Iak serum, but not with mouse normal serum. Scatchard analysis of this binding activity also showed a single receptor type on sperm cells. These results were directly confirmed morphologically by taking autoradiography of sperm cells binding foreign DNA.

Two different activities of alkaline phosphatase in cultured mammalian cells

Alkaline phosphatase activities in various mammalian cell strains in culture, some of which had been grown in protein-free synthetic media, were investigated and characterized. Two distinctly different activities of alkaline phosphatase were found in crude extracts of various cell strains. The first activity (designated alkaline phosphatase I) was the highest around the range of pH 10.0 and inhibited by cyanide or β -mercapto-ethanol. This activity was mainly detected in particulate fractions of cells. The second was shown to be optimal at pH 8.6 and inhibited by p -chloromercuribenzoate (designated alkaline phosphatase II). Among various cell strains examined, the former activity was detected only in some of them, whereas the latter type was present in each strain. These two activities were separated from each other by DEAE-cellulose chromatography.

Decrease in CuZn‐superoxide dismutase mRNA level during differentiation of human monocytic and promyelotic leukemia cells

Change in the level of CuZn‐superoxide dismutase (SOD) mRNA was examined using a molecular probe during differentiation of human monocytic leukemia U937 cells or promyelotic leukemia HL‐60 cells induced by either 12‐O‐tetradecanoyl‐phorbol‐13‐acetate (TPA) or dimethylsulfoxide (DMSO). CuZn‐SOD mRNA levels were found to decrease during the course of differentiation, and this response is specific for differentiation, since the treatment of human B cell leukemia cells or normal diploid fibroblasts with TPA failed to have any effect on the level of CuZn‐SOD mRNA. The activity of CuZn‐SOD in U937 cells also decreased during differentiation, but following that of the CuZn‐SOD mRNA level. The expression of the CuZn‐SOD gene is thus concluded to diminish during the differentiation of HL‐60 and U937 cells.

Induction of c-fos proto-oncogene by a chemotactic peptide in human peripheral granulocytes

The chemotactic peptide, fMet‐Leu‐Phe (fMLP), induced proto‐oncogene c‐&f;os MRNA in purified human peripheral granulocytes. The induction was transient, and was inhibited by pertussis toxin or by an inhibitor of protein kinase C. These results suggest that activation of a guanine nucleotide‐binding protein and of protein kinase C is involved in c‐&f;os induction in granulocytes.

Restrictive effect of prophage λ on DNA degradation in Escherichia coli cells

Abstract The rates of DNA degradation in λ-lysogenic and non-lysogenic cells caused by colicin E2 were compared. The sensitivities of the two types of cell to colicin E2 were identical, but the rate of DNA degradation in the λ lysogen was slower than in the non-lysogen. This difference was not due to reutilization of degradation products for the synthesis of phage DNA in colicin E2-treated cells. It was shown that this phenomenon was a result of restriction of exonucleolytic degradation by prophage.