Transcriptional regulation of the c-jun gene by retinoic acid and E1A during differentiation of F9 cells

Differentiation of mouse F9 embryonal carcinoma (EC) cells can be induced by exposure to retinoic acid (RA) or by expression of adenovirus E1A. The transcription of the c-jun gene is stimulated by either RA or E1A. We report here that both RA and E1A strongly induce the expression of chloramphenicol acetyltransferase (CAT) from c-jun promoter/CAT reporter construct (c-jun/CAT), which is stably integrated into F9 cells, in a manner that is independent of both copy number and integration locus. The induction of c-jun/CAT expression is observed in undifferentiated F9 cells, but not in differentiated F9 cells, adenovirus-infected F9 cells or HeLa cells. Deletion analysis of the promoter region of the c-jun gene indicates that the sequence elements required for the RA- and E1A-mediated induction are identical and they have been defined as a region of 145 bp between -190 and -46 of the 5' flanking region of c-jun. This RA and E1A response element (RERE) contains five variants of the motif CGCGGTGACGNT. The upstream two motifs are adjacent and extend in opposite directions, creating an imperfect palindrome. The downstream four motifs are located at 35 or 36 bp intervals in the same orientation. Substitution and insertion analysis indicates that these motifs and their regular intervals are important for the activity of the RERE.

Enhancement by IL-1 beta and IFN-gamma of platelet activation: adhesion to leukocytes via GMP-140/PADGEM protein (CD62)

We have examined the effect of inflammatory cytokines on the platelet activation. IL-1 beta and IFN-gamma were found to enhance the adhesion of thrombin-treated platelets to monocytic leukemia cells (U937), when the adhesion was assayed by platelet-mediated cell agglutination. The agglutination was inhibited by a monoclonal anti-GMP140 antibody or EDTA, suggesting that the enhanced platelet adhesion to the leukemic cells was mediated by GMP140. In addition, these cytokines also increased the release of 5-HT from platelets in the presence of a low concentration of thrombin. These data suggest that platelet functions are regulated by the cytokines and that activated platelets participate in inflammatory process.

TNF-mediated cytotoxicity. Importance of intracellular cGMP level for determining TNF-sensitivity

Previous work on the cytolytic action of activated macrophages indicated that tumor necrosis factor (TNF) showed synergistic cytolytic activity with NO, which has been shown to act as a cyclic GMP (cGMP) generator [Higuchi et al., J. Immun. 144, 1425-1431, (1990)]. In this study, we investigated the relationship between the accumulation of intracellular cGMP and the cytotoxic action of TNF. It was demonstrated that TNF-mediated cell lysis was closely related to the background level of intracellular cGMP, and that the accumulation of cGMP within TNF resistant cells induced TNF sensitivity. We reached these conclusions on the basis of the following results; (1) agents (sodium nitroprusside and isobutylmethylxantine) that cause the accumulation of cGMP intracellularly increased the TNF-sensitivity of TNF-resistant cells; (2) the addition of dibutyryl cGMP to TNF-resistant cells increased the TNF-sensitivity; and (3) treatment at 40 degrees C or agents such as interferon gamma and actinomycin D, that synergistically kill tumor cells together with TNF, potentially increased the cGMP level. Therefore, intracellular cGMP may be one of the key molecules that lead to cell death caused by TNF.

Mechanism of immunosuppression by a murine non-specific suppressor T cell line, SB-1

The mechanism of immunosuppression by a murine non-specific suppressor T cell clone (SB-1), which was established from concanavalin A (Con A)-activated murine spleen cells [Jpn. J. Exp. Med., 53, 139 (1983)], was investigated. SB-1-induced decrease of antigen non-specific plaque-forming cell (PFC) response was restored by the addition of 5 x 10(-6) M indomethacin, an inhibitor of cyclooxygenase. On the other hand, suppressive activity for antigen non-specific PFC response was found in the culture supernatant of SB-1 cells in the presence of proteose peptone-elicited macrophages. This induction of the suppressive activity was also inhibited by 5 x 10(-6) M indomethacin. Furthermore, 10(-5) M prostaglandine E2 (PGE2) was found to induce suppressive activity in the culture supernatant of SB-1 cells. 10(-5) M PGE2 did not suppress interleukin-2 (IL-2)-dependent proliferation of SB-1 cells, but increased a small quantity of protein synthesis and deoxyribonucleic acid (DNA) synthesis of SB-1 cells in the absence of IL-2. These results suggest that a cyclooxygenase product(s) such as PGE2 from macrophages may induce production of soluble suppressor factors in SB-1 cells. To characterize these suppressor factors, those in the culture supernatant of PGE2-stimulated SB-1 cells were partially purified by ammonium sulfate fractionation and sequential column chromatographies on diethylaminoethyl (DEAE)-cellulofine and Sephacryl S-200. Suppressor activities were eluted at the positions corresponding to the molecular masses of 10, 30, 70 and over 70 kilodalton (kDa) on Sephacryl S-200 column chromatography.(ABSTRACT TRUNCATED AT 250 WORDS)

Ductal carcinoma of the breast. An analysis of proportions of intraductal and invasive components

One hundred and ninety patients with mammary ductal carcinoma were studied to evaluate the correlation of proportions of intraductal and invasive tumor growth to histologic and immunohistochemical features. Initially, attempts were made to divide the cases into 6 groups according to the proportion of extraductal invasive areas within the whole tumor. It has been found that ductal carcinoma could be divided, on this criterion, into 2 groups. One comprised tumors in which invasive areas made up less than 20% of the tumor, the other included those with invasive areas exceeding 20%. In the former, intraductal and invasive components exhibited a lower grade of nuclear and tumor component and a higher incidence of cells with CEA immune positivity. The latter manifested higher grades in both intraductal and invasive components and a lower incidence of CEA positive cells. Many of the latter tumors had a solid or comedo-like growing pattern of the intraductal component. There was a significant difference in the prognosis between the two categories. We conclude that like intraductal carcinomas, invasive ductal carcinomas with a predominant intraductal component should be considered a lower grade malignancy.

Low-molecular-weight GTP-binding proteins serving as ADP-ribosylation substrate for ADP-ribosyltransferase from Clostridium botulinum and their relation to phosphoinositides metabolism in thymocytes

ADP-ribosyltransferase from Clostridium botulinum type C strain was found to induce an increase of inositol phosphates (IPs) formation in murine thymocytes membranes. Incubation of electropermeabilized murine thymocytes with the enzyme also caused an increase of IPs formation in the cells. This increase of IPs formation in the enzyme-treated membranes and electropermeabilized cells was dependent on the amount of both NAD and the enzyme, suggesting that the stimulation of phosphoinositide-specific phospholipase C (PLC) was related to ADP-ribosylation of membrane proteins by the enzyme. On the other hand, in calf and murine thymocytes two proteins with the same molecular weight of 21,000 were found to be ADP-ribosylated by the botulinum ADP-ribosyltransferase. A minor ADP-ribosylation substrate was shown by two-dimensional polyacrylamide gel electrophoresis to be G21k, a low-molecular-weight GTP-binding protein (G protein) suggested previously by us to be involved in PLC regulation [Wang, P. et al. (1987) J. Biochem. 102, 1275-1287; (1988) 103, 137-142; and (1989) 105, 461-466], and the other major ADP-ribosylation substrate was identified as a rho A protein. Under the experimental conditions of the IPs formation study, ADP-ribosylation of both G21k and rho A proteins by botulinum ADP-ribosyltransferase in membranes and permeabilized cells was observed. These results suggest that botulinum ADP-ribosyltransferase-induced PLC stimulation in thymocytes is closely correlated with ADP-ribosylation of the low-molecular-weight G proteins.

Purification and partial amino acid sequences of phosphoinositide-specific phospholipase C of Drosophila eye

To examine whether the norpA (no receptor potential A) gene encodes a phosphoinositide-specific phospholipase C (PLC) in the eye of Drosophila, a major PLC in the extract from normal Drosophila heads, which was absent in the extract from norpA mutant heads, and purified and its partial amino acid sequences were determined. The purification of the major PLC in KCl extract from normal Drosophila heads was achieved by sequential column chromatography on DEAE-Sepharose CL-6B, Mono Q, Superose 12, Mono S, second Mono S, and second Mono Q, followed by column chromatography on Superose 12 in the presence of 1% sodium cholate. The enzyme thus purified was found to be homogeneous on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The molecular weight of the enzyme was estimated to be 98,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified enzyme hydrolyzed both phosphatidylinositol (PI) and phosphatidylinositol 4,5-bisphosphate (PIP2). Interestingly, the calcium and pH requirements for activation of the crude enzyme (KCl extract) were quite different from those of partially purified enzyme (active fraction from second Mono Q column). The maximal activity for PIP2 hydrolysis was observed at calcium concentrations between 10(-7) and 10(-5) M for both the crude and partially purified enzymes. On the other hand, the activity for PI hydrolysis of the crude enzyme increased with increasing calcium concentrations, while that of the partially purified enzyme reached a maximum at calcium concentrations between 10(-6) and 10(-4) M, and decreased at millimollar concentration. The pH dependences for PI hydrolysis of the crude enzyme and the partially purified enzyme were similar. The crude enzyme hydrolyzed PIP2 over a broad pH range from 6 to 8.5, while the activity of the partially purified enzyme monotonously increased with increasing pH. The partial amino acid sequences were determined by treating the purified enzyme with endopeptidase Lys-C; the resultant peptide fragments were purified on a high performance liquid chromatography-reverse phase column and then sequenced with sequencer. The obtained sequences were found to be a part of the deduced amino acid sequences of cDNA which was suggested to be norpA gene.

Concanavalin A-induced receptor aggregation stimulates the tyrosine kinase activity of the insulin receptor in intact cells

Concanavalin A (ConA) stimulated the phosphorylation of the beta-subunit of the insulin receptor and an Mr-185,000 protein on serine and tyrosine residues in intact H-35 rat hepatoma cells. This Mr-185,000 protein whose phosphorylation was stimulated by ConA was identical to pp185, a protein reported previously to be a putative endogenous substrate for the insulin receptor tyrosine kinase in rat hepatoma cells. In Chinese hamster ovary (CHO) cells transfected with cDNA of the human insulin receptor, tyrosine-phosphorylation of pp185 was strongly enhanced by ConA compared with the controls, suggesting that the induction of tyrosine-phosphorylation of pp185 was due to stimulation of the insulin receptor kinase by ConA. Moreover, monovalent ConA only slightly induced the tyrosine-phosphorylation of pp185, which was enhanced by the addition of anti-ConA IgG, suggesting that ConA stimulated the insulin receptor kinase mainly by the receptor cross-linking or aggregation in intact cells. These data suggest that the insulin-mimetic action of ConA is related to the autophosphorylation and activation of the insulin receptor tyrosine kinase, as well as the subsequent phosphorylation of pp185 in intact cells.

[Hospital and district differences in susceptibilities to antibiotics of main clinical isolates]

A nationwide survey of susceptibilities of Staphylococcus aureus, Escherichia coli, Klebsiella sp. and Proteus mirabilis initiated in 1980 was continued in 1986. This report documents differences in susceptibilities of clinical isolates of the above microorganisms to ampicillin (ABPC), cefazolin (CEZ), cefmetazole (CMZ) and gentamicin (GM) among general hospitals throughout Japan. Clinical isolates of each species of microorganisms which were collected in 24 hospitals made up each study group and were collected at the Kosei General Hospital, Tokyo, from April 1980 to March 1986. We compared the variability in the resistant rates (MIC greater than or equal to 25 micrograms/ml) and MICs of each antibiotic for 50% and 80% of the isolates among the hospitals. MICs were determined by the serial 2 fold agar plate dilution method, standardized by the Japan Society of Chemotherapy, with an inoculum of approximately 10(6) CFU/ml or 10(8) CFU/ml. Susceptibility patterns of S. aureus to ABPC, CEZ and GM, of E. coli to ABPC, of Klebsiella sp. to CEZ and GM and of P. mirabilis to ABPC, CEZ and GM varied from hospital to hospital. On the other hand, the differences in the susceptibility patterns among the 6 districts of Japan were not obvious, because the differences were affected by different susceptibility patterns of each hospital located in each district.

N-(cyclohexylcarbonyl)-D-phenylalanines and related compounds. A new class of oral hypoglycemic agents. 2

A series of analogues of N-(cyclohexylcarbonyl)-D-phenylalanine (5) have been synthesized and evaluated for their hypoglycemic activity. Relationships were studied between the activity and the three-dimensional structure of the acyl moiety, which was characterized by high-resolution 1H NMR spectroscopy and MNDO calculations. The role of the carboxyl group of the phenylalanine moiety was also studied by comparing the activities of the enantiomers, the decarboxyl derivative, the esters, and the amides of the phenylalanine derivatives. Thus, the structural requirements for possessing hypoglycemic activity was elucidated and a highly active compound, N-[(trans-4-isopropylcyclohexyl)carbonyl]-D-phenylalanine (13) was obtained, which showed a 20% blood glucose decrease at an oral dose of 1.6 mg/kg in fasted normal mice.

Binding of activated macrophages to tumor cells through a macrophage lectin and its role in macrophage tumoricidal activity

A 45-60 kDa Gal/GalNAc-specific macrophage lectin was found to participate in the interaction between tumor cells and tumoricidal macrophages activated by an antitumor streptococcal preparation, OK-432, and in the tumoricidal activity of the activated macrophages. The binding between OK-432-elicited activated macrophages and murine mastocytoma P-815 cells was inhibited on preincubation of the macrophages with a neoglycoprotein (Gal-BSA) or a complex-type glycopeptide (unit B) which was a specific inhibitor of the macrophage lectin. This binding of the macrophages to P-815 cells was also inhibited on the addition of anti-macrophage lectin antiserum. Contrary to the case of OK-432-elicited macrophages, the binding of thioglycolate-elicited (responsive) macrophages to P-815 cells was inhibited only a little by Gal-BSA and unit B, and not inhibited by the antiserum. Furthermore, the tumoricidal activity of the activated macrophages was inhibited by the addition of the anti-macrophage lectin antiserum. These results suggest that the binding of activated macrophages to tumor cells through the Gal/GalNAc-specific macrophage lectin is an important part of the tumor cell killing mechanism.

Purification and partial amino acid sequences of a phospholipase C-associated GTP-binding protein from calf thymocytes

We recently identified a phosphoinositide-specific phospholipase C (PI-PLC)-stimulating GTP-binding protein (G protein) in calf thymocyte cytosol (Wang, P., Toyoshima, S., & Osawa, T. (1987) J. Biochem. 102, 1275-1287; and (1988) 103, 137-142). In this study we completely purified a G protein whose properties are quite similar to the G protein mentioned above from the calf thymocyte membrane and determined partial amino acid sequences of it. The purification was achieved by first treating the membrane with GTP gamma S, followed by sequential column chromatographies on DEAE-Sepharose CL-6B, Sephacryl S-200, Mono Q, and Mono S. The G protein was purified in a GTP gamma S-binding form and assayed as to the radioactivity of the [35S]GTP gamma S-bound PI-PLC-associated G protein standard obtained from calf thymocyte cytosol. The purified G protein could stimulate the activity of a partially purified PI-PLC for phosphatidylinositol 4,5-bisphosphate hydrolysis. From approximately 5.6 g of membrane protein we obtained about 5 micrograms of a purified sample. The purified G protein showed a molecular weight of 21 kDa on SDS-PAGE and one of 25 kDa on gel filtration. The partial amino acid sequences were determined by treating the purified sample with lysylendopeptidase, purifying the resultant peptide fragments on a HPLC-reverse phase column and then sequencing the peptide fragments with a sequencer. Comparison of the obtained sequences with those of known lower molecular weight GTP-binding proteins suggested that, although structurally similar to rho gene products, this is a novel G protein.

Sugar binding specificities of anti-H(O) lectins disclosed by use of fucose-containing human milk oligosaccharides as binding inhibitors

The binding to normal and sialidase-treated human erythrocytes of six 125I-labeled lectins [Ulex europeus lectin I (UEA-1) and II (UEA-II), Laburnum alpinum lectins I (LAA-I) and II (LAA-II), and Cytisus multiflorus lectins I (CMA-I) and II (CMA-II)], was studied in detail. Quantitative inhibition assays of the lectin binding to the cells were also performed with various human milk oligosaccharides as inhibitors. Based on a comparison of the inhibition constants of the inhibitors thus obtained with the association constants of the lectins to the cells, the relative activities of cell surface blood group antigens toward the lectins are discussed.

Concanavalin A receptor(s) possibly interacts with at least two kinds of GTP-binding proteins in murine thymocytes

A part of the GTP gamma S-binding activity in murine thymocyte membranes was found to have affinity to a concanavalin A (Con A)-Sepharose column. The material was identified as Gi (inhibitory GTP-binding protein) on the basis of the molecular weight and by islet activating protein-dependent ADP-ribosylation and anti-alpha i (alpha subunit of Gi) immunoblotting. However, when the membranes prepared from Con A-stimulated thymocytes were used, no GTP gamma S-binding activity was detected in the Con A-bound fraction, suggesting that Gi physically and specifically associated with Con A acceptors dissociates upon Con A stimulation. Furthermore, another GTP gamma S-binding protein (25 kDa), which is quite similar to a novel phosphoinositide-specific phospholipase C (PI-PLC)-associated G protein in calf thymocytes (Wang, P., Toyoshima, S., & Osawa, T. (1988) J. Biochem. 103, 137-142), was detected among the Con A-Sepharose-bound proteins with the chemical cross-linking technique. When the 40 kDa and 25 kDa G proteins associated with Con A receptor(s) were isolated and their direct effects on the activity of partially purified PI-PLC as to phosphatidylinositol 4,5-bisphosphate hydrolysis were examined, the 25 kDa G protein was found to enhance the PI-PLC activity more effectively. On the other hand, pretreatment of cells with islet-activating protein completely abolished the inhibitory effect of Con A on the prostaglandin E1 and isoproterenol-induced increases of cellular cAMP.(ABSTRACT TRUNCATED AT 250 WORDS)

N-acylphenylalanines and related compounds. A new class of oral hypoglycemic agents

N-Benzoyl-DL-phenylalanine (1) was found to possess hypoglycemic activity. A series of the analogues of compound 1 were prepared and evaluated for their blood glucose lowering activity. Both the steric effects of the phenylalanine moiety and the effects of variations in the acyl moiety were investigated. This study elucidated some of the structure-activity relationships and led to the development of N-(4-ethylbenzoyl)-D-phenylalanine (34), which was 50 times more potent than the initial compound 1.

Purification and characterization of a lectin-like molecule specific for galactose/N-acetyl-galactosamine from tumoricidal macrophages

A lectin-like molecule (macrophage lectin) was purified from murine peritoneal exudate macrophages which had been induced with an antitumor streptococcal preparation, OK-432. The purified macrophage lectin from both 3H-labeled and unlabeled macrophages after rechromatography on a beta-D-galactose-Bio-Gel P-100 column gave a broad single band corresponding to 45-60 kDa on SDS-polyacrylamide gel electrophoresis (SDS-PAGE). The broadness of this band was due to high N-glycosylation of the lectin, because the lectin gave a compact band corresponding to 35 kDa on SDS-PAGE after deglycosylation. The lectin required Ca2+ for binding and showed an optimum pH of around 6. The sugar specificity of the lectin was examined by means of an inhibition assay using simple sugars and neoglycoproteins. The lectin was found to be specific for D-galactose/N-acetyl-D-galactosamine, and not inhibited with D-mannose or N-acetyl-D-glucosamine at all. The lectin was detected on the surface of OK-432-elicited and thioglycolate-elicited macrophages, but it was not detected on resident macrophages. Moreover, the binding of tumor cells to macrophages was inhibited by the addition of the purified lectin to the binding mixture. These results suggest that this lectin is expressed on the surface of activated macrophages, and that it participates in the interaction between tumoricidal macrophages and tumor cells.

Concanavalin A-induced translocation of part of the GTP-binding activity from the membrane to the cytosol in murine thymocytes

Concanavalin A (Con A) stimulation resulted in the rapid redistribution of part of the GTP-binding activity from the membrane to the cytosol in murine thymocytes. This change in GTP-binding activity was dependent on the Con A concentration. To investigate the relationship between this redistribution and phospholipase C (PLC) activity, the effect of GTP gamma S on the cytosol PLC activity was also examined, and it was found that GTP gamma S enhanced the phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis activity in the cytosol of Con A-stimulated thymocytes more than in that of unstimulated thymocytes. This enhancement by GTP gamma S was also dependent on the Con A concentration. The results suggest that in murine thymocytes, the GTP-binding protein (G-protein) involved in the regulation of PLC activity may be translocated from the membrane to the cytosol upon Con A stimulation. Besides, the dose dependence curve for the change in the GTP gamma S-binding activity was similar to that for inositol phosphates formation in Con A-stimulated thymocytes, suggesting that the translocation of the G-protein is closely related to PLC activation. Furthermore, the effects of cytosol fractions containing the 38-43 and 23-28 kDa GTP-binding subunits of G-proteins on the PIP2 hydrolysis activity of partially purified PLC were examined. The fraction containing the 23-28 kDa subunit evidently enhanced the PLC activity but that containing the 38-43 kDa subunit enhanced the activity to a much lower extent. Moreover, the 23-28 kDa subunit fraction of Con A-stimulated thymocytes was more effective as to enhancement of the PLC activity than that of unstimulated thymocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Possible mechanism of inhibition of experimental pulmonary metastasis of mouse colon adenocarcinoma 26 sublines by a sialic acid: nucleoside conjugate

As described previously (I. Kijima-Suda et al., Cancer Res., 46: 858-862, 1986), a sialyltransferase inhibitor, 5-fluoro-2',3'-isopropylidene-5'-O-(4-N-acetyl-2,4-dideoxy-3,6,7,8-tetra -O- acetyl-1-methoxycarbonyl-D-glycero-alpha-D-galactooctapyranosyl)ur idine (KI-8110), inhibits pulmonary metastasis of murine colon adenocarcinoma 26 sublines of high (NL-17) and low (NL-44) metastatic potential. To investigate the mechanism of this inhibition, the effect of KI-8110 on the metastatic cascade, especially on the interaction between tumor cells and platelets which may play a crucial role in tumor cell metastasis, was examined. NL-17 cells induced irreversible platelet aggregation in heparinized human platelet-rich plasma in vitro. This activity was reduced by pretreatment of the tumor cells with KI-8110. Inhibition of aggregation was also induced by the treatment of tumor cells with neuraminidase or Limax flavus agglutinin, a lectin specific for sialic acid. Sialic acid, fucose, sialyllactose, and bovine submaxillary mucin inhibited this tumor cell-induced platelet aggregation, while galactose, mannose, lactose, alpha 1-acid glycoprotein, fetuin, and asialo-bovine submaxillary mucin did not. KI-8110 also inhibited platelet-derived growth factor-dependent growth of NL-17 cells, but showed no effect on insulin or epidermal growth factor-dependent growth of the tumor cells. Platelet-derived growth factor-induced phosphorylation of membrane protein was reduced by treatment of NL-17 cells with KI-8110. The same result was obtained in the neuraminidase-treated membrane fraction of NL-17 cells. These results suggest that KI-8110 inhibits experimental tumor cell metastasis by inhibiting the interaction between tumor cells and host platelets in at least two pathways, and this may be due to a reduction of sialic acid contents of the membrane surface of tumor cells.

Adenomyoepithelioma of the breast. A case report with an immunohistochemical study

We treated a 62-year-old woman with adenomyoepithelioma of the breast, an extremely rare tumor, which showed a bicellular pattern of ductal and myoepithelial elements bearing some histologic resemblance to pleomorphic adenoma of the salivary gland. The tumor was made up of cells positive for actin and S-100 protein, and some positive for epithelial membrane antigen (EMA). Thus, this tumor showed biphasic differentiation towards myoepithelial cells and to duct epithelial cells. Compared with findings in related tumors reported in the literature, the myoepithelial cells in the present tumor were less frequently spindle-shaped and had abundant eosinophilic or clear cytoplasm. A simple mastectomy was done and at the time of writing 20 months later there has been no recurrence. Adjuvant chemotherapy was not prescribed.

Properties of a novel GTP-binding protein which is associated with soluble phosphoinositides-specific phospholipase C

Recently we demonstrated the presence in calf thymocytes of a GTP-binding protein (G-protein) composed of three polypeptides, 54, 41, and 27 kDa, which was physically and functionally associated with a soluble phosphoinositides-specific phospholipase C (PI-phospholipase C). The properties of this G protein were further investigated with the following results. 1) In addition to the ability to bind [35S]guanosine-5'-[gamma-thio]triphosphate (GTP gamma S), the G-protein exhibited GTPase activity, which was enhanced by Mg2+, phosphatidylethanolamine, phosphatidylserine, and phosphatidylinositol, but inhibited by sodium cholate, GTP gamma S and F-.2) The 54-kDa polypeptide was ADP-ribosylated by pertussis toxin and also by endogenous membrane-bound ADP-ribosyltransferase, but none of these three polypeptides was ADP-ribosylated by cholera toxin. 3) The G-protein did not cross-react with either anti-rat brain alpha 1 (alpha-subunit of inhibitory G-protein, G1), alpha 0 (alpha-subunit of other G1-like G-protein, G0) or beta gamma antibodies. 4) Incubation of this G Protein with GTP gamma S caused dissociation of the three polypeptides. 5) The 27 kDa polypeptide showed GTP-binding activity and enhanced the phosphatidylinositol 4,5-bisphosphate hydrolysis by purified PI-phospholipase C. These results suggest that the PI-phospholipase C-associated G-protein in calf thymocytes may be a novel one and that it is involved in the regulation of PI-phospholipase C activity.

Physical and functional association of cytosolic inositolphospholipid-specific phospholipase C of calf thymocytes with a GTP-binding protein

A soluble inositolphospholipid-specific phospholipase C (PI-phospholipase C) has been purified 5,800-fold from the cytosolic fraction of calf thymocytes. The purification was achieved by sequential column chromatographies on DEAE-Sepharose CL-6B, heparin-Sepharose CL-6B, Sephacryl S-300, Mono S, and Superose 12, followed by column chromatography on Sephadex G-100 in the presence of 1% sodium cholate. The enzyme thus purified was found to be homogeneous on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weight of the enzyme was estimated to be 68 kDa by SDS-PAGE. The enzyme is specific for inositol phospholipids. Phosphatidylinositol and phosphatidylinositol 4,5-bisphosphate (PIP2) were hydrolyzed, but phosphatidylcholine and phosphatidylethanolamine were not affected by the enzyme. GTP gamma S-binding activity was detected in the enzyme fractions after all the purification steps, but not in the final enzyme preparation. The PI-phospholipase C and GTP gamma S-binding activities in the partially purified enzyme preparation could be separated by the column chromatography on Sephadex G-100 only in the presence of 1% sodium cholate. Thus, the soluble PI-phospholipase C has affinity to a GTP-binding protein. SDS-PAGE of the GTP-binding fractions eluted from the Sephadex G-100 column gave three visible bands of 54, 41, and 27 kDa polypeptide was specifically ADP-ribosylated by pertussis toxin. Furthermore, it was found that GTP and GTP gamma S (10 microM and 1 mM) could enhance the PIP2 hydrolysis activity of the partially purified enzyme in the presence of 3 mM EGTA, but the purified enzyme after separation from the GTP-binding activity was not affected by GTP and GTP gamma S. The soluble PI-phospholipase C of calf thymocytes may be not only physically but also functionally associated with a GTP-binding protein.

Protein-O-carboxylmethyltransferase from cytosol and membranes of chicken erythrocytes

Cytosolic protein-O-carboxylmethyltransferase was purified more than 4,000-fold in specific activity and membrane-associated protein-O-carboxylmethyltransferase carboxymethylase about 900-fold from chicken erythrocytes by use of a combination of affinity chromatography on immobilized S-adenosyl-L-homocysteine and gel filtration on Sephacryl S-200 (Pharmacia), together with 3-((3-cholamidopropyl)-dimethylammonio)-1-propane-sulfonate as a detergent to solubilize the membrane-associated enzyme. The two enzymes were characterized by examining the dependence of their activity on pH and on concentration of S-adenosyl-L-methionine using fetuin as an exogenous methyl-acceptor substrate, and were found to differ somewhat. The cytosolic enzyme had a pH optimum of 6.0 with an apparent Km value of 2.1 microM for S-adenosyl-L-methionine, whereas corresponding values for the membrane-associated enzyme were 6.5 and 0.71 microM. This report deals with the biochemical differences between purified cytosolic and membrane-associated protein carboxymethylase from the same cell source.

Sebaceous gland tumor of the ovary

A sebaceous gland tumor of the ovary was detected in a 60-year-old woman who underwent right salpingo-oophorectomy for a right ovarian cyst. The cyst was unilocular, weighed 820 g, and was filled with sebaceous material containing a few hair shafts. There was a protruded mass composed of lobules of mature or immature sebaceous cells over the inner surface of the cyst wall. She has been well for 4 years and 2 months after the surgery. This is the second well-documented case of this extremely rare type of tumor. This lesion is teratogenic with unilateral development of the sebaceous glands and malignant characteristics are nil.