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E Maruyama

Publications and source records attributed to E Maruyama.

17 recordsLinked to original sources
PubMed1997

SHP-1 is involved in neuronal differentiation of P19 embryonic carcinoma cells.

Accumulating evidence suggests that tyrosine phosphorylation plays an important role in the development of the central nervous system and in the differentiation of neuronal cells. To identify protein tyrosine phosphatases (PTPs) that might regulate signaling events leading to neuronal cell differentiation, we cloned PTP genes from the murine P19 embryonic carcinoma cell line and examined the change of their expression during differentiation. P19 cells are known to be pluripotent and the aggregate formation and subsequent replating in the presence of retinoic acid (RA) induce growth arrest and neuronal differentiation. The results demonstrated that among several PTP genes expressed in P19 cells, a cytosolic Src homology region 2 domain-containing PTP, SHP-1, is expressed highly in undifferentiated P19 cells, but is reduced to an undetectable level at day 3 after replating in the presence of RA. Further, SHP-1 was tyrosine-phosphorylated and activated at day 1 after replating. When ectopic SHP-1 was constitutively expressed, P19 cells continued to proliferate and failed to differentiate upon stimulation with RA. Collectively, these results suggest that the regulated expression and activity of SHP-1 may be involved in the neuronal differentiation of P19 cells.

Animals↗
PubMed1996

Biochemical characterization of mouse brain necdin.

Necdin is a protein encoded by neural differentiation-specific mRNA derived from embryonal carcinoma cells (P19). Necdin of mouse brain was characterized by Western blotting and silver-staining analysis by using affinity purified antibodies to 17 synthetic peptides of deduced C-terminal amino acids. Necdin exhibits a molecular mass of 51 kDa on SDS/PAGE, and is localized in the S1 and S2 nucleosomal fractions. Sonicated necdin is found in all fractions of Sephacryl S-300 gel filtration chromatography, with a peak at 700 kDa. Necdin is released on microsomal nuclease digestion, which is essential for electrophoretic migration on acetic acid/urea/Triton gels, suggesting that it could be a DNA-binding protein. Nucleosomal necdin shows two peaks at approx. 10 S and approx. 20 S on sucrose gradient centrifugation in the presence of 0.6 M NaCl, and a single peak in the presence of 2.0 M NaCl. Necdin forms a huge complex through chemical cross-linking with glutaraldehyde or dimethyl sulphate. The silver-staining intensity of the 51 kDa band corresponds to the decrease in the immuno-staining in a reagent concentration-dependent manner. Necdin binds tightly to a double-stranded DNA affinity chromatography column, and can be eluted from it with 2.0 M NaCl after washing with 0.6 M NaCl (approx. 100 ng per ml of gel). This purified necdin exhibits of pI of 9.1 on isoelectric focusing. The nucleosomal necdin complex (>200 kDa) was adsorbed on an organomercurial agarose affinity chromatography column and was eluted with 10 mM DTT, revealing that necdin is possibly involved in the transactive nucleosomal complex. These data show that necdin is a nuclear basic DNA-binding protein that associates with other molecules to regulate transcriptionally active genes and nuclear function.

Aging↗
PubMed1993

Characterization of over-expressed alkaline phosphodiesterase I in tumour-derived fibroblasts from patients with neurofibromatosis.

Alkaline phosphodiesterase I from cultured fibroblasts from patients with neurofibromatosis was partially purified and characterized following extraction with Triton X-100, and fractionation with high-performance liquid chromatography. Some properties were compared with the enzyme extracted from normal-appearing fibroblasts. The isoelectric points of both the tumour and normal-appearing cell enzymes were 6.0. The enzyme required Zn2+ for its activity, was heat labile, and nicked superhelical covalently closed circular phi X174 DNA. The activity was inhibited by GTP, DTT and EDTA. The native molecular weight of alkaline phosphodiesterase I was determined to be 430,000. No differences were found in properties of the tumour-derived and normal cell enzymes. On purification it was observed that the peak pattern of enzyme activity corresponded to that of 125 kDa protein, which was more abundant upon SDS-PAGE analysis in tumour cells than in normal cells. The most active fraction of isoelectric focusing, which was performed using disulfide cross-linked polyacrylamide gel, was used to produce an antibody. The bands of 125, 60 and 40 kDa were immuno-stained in tumour cell preparation. These results indicate that alkaline phosphodiesterase I, of which the molecular weight is probably 125 kDa, is over-expressed in tumour-derived fibroblasts from neurofibromatosis patients.

Antibodies, Neoplasm↗
PubMed1993

Purification and amino acid microsequencing of alkaline phosphodiesterase I from calf kidney.

Alkaline phosphodiesterase I was purified from calf kidney following extraction with 0.5% Triton X-100 and then fractionation with a Rotfor cell and high-pressure liquid chromatography. The isoelectric point of alkaline phosphodiesterase I was 5.9. Both the native and the subunit molecular weight of alkaline phosphodiesterase I was determined to be 125 kDa. The N-terminus of its amino acid sequence appeared to be blocked. The immobilized protein, separated by gel electrophoresis and transblotted to a polyvinylidene difluoride membrane, was digested on the membrane by proteases and separated by reverse-phase high-performance liquid chromatography. Eighty one amino acids were sequenced. One of the internal sequences was identical with that of an active-site-containing fragment from calf intestinal enzyme, as reported by Culp et al. (1985).

Amino Acid Sequence↗
PubMed1992

Nicotinamide-induced activity of alkaline phosphodiesterase I toward tumor-derived cultured cells from neurofibromatosis patients.

Membrane-bound alkaline phosphodiesterase I was investigated in control fibroblasts and tumor-derived fibroblasts from patients with neurofibromatosis. Alkaline phosphodiesterase I activity of tumor-derived cells increased in a dose response to nicotinamide (0-9 mM) in culture; 5'-thymidine p-nitrophenyl phosphate was used as substrate. The enzyme activity increased 1.7-fold after 30 h of incubation with 9 mM nicotinamide, and after 3 weeks increased 5-fold. The nicotinamide-dependent enhancement of alkaline phosphodiesterase I activity was inhibited by actinomycin D, which specifically blocks RNA synthesis, but not by cycloheximide. These results suggest that the increase in the enzyme activity caused by nicotinamide was due to induction of alkaline phosphodiesterase I at the transcriptional level in tumor-derived cells. The metabolic effect of nicotinamide on alkaline phosphodiesterase I may be related to tumorigenicity in neurofibromatosis.

Enzyme Induction↗
PubMed1991

The effect of tacrine (THA) on cycloheximide- and basal forebrain lesion-induced memory deficit in rats.

The effects of 9-amino-1,2,3,4-tetrahydroacridine (tacrine), an active acetylcholinesterase inhibitor, on cycloheximide- and basal forebrain (BF) lesion-induced memory deficit in the water maze and passive avoidance task were investigated. While cycloheximide (1.5 mg/kg, s.c.) produced amnesia in the passive avoidance task, chronic administration of tacrine (1, 3 and 10 mg/kg, once a day for 1 week) improved the amnesia. BF lesion produced amnesia in both the water maze and passive avoidance tasks. Chronic tacrine (0.1-3 mg/kg, passive avoidance task, or 0.3 mg/kg, water maze task, once a day for 1 week) improved BF lesion-induced amnesia in the passive avoidance and water maze tasks. These results suggest that tacrine may be useful for senile dementia.

Administration, Oral↗
PubMed1988

Reversal of resistance to vincristine in P388 leukemia by various polycyclic clinical drugs, with a special emphasis on quinacrine.

We investigated several lipophilic drugs with a polycyclic structure for their effect on the net uptake of vincristine in vincristine-resistant P388 leukemia cells. Fourteen of 23 agents promoted vincristine uptake in the resistant cells. The net increase in vincristine uptake was caused by prevention of its outward transport rather than by stimulation of inward transport. Some of these drugs, e.g., quinacrine, dilazep, syrosingopine, simetride, etc., remarkably potentiated the cytotoxicity of vincristine against the resistant cells in vitro. Quinacrine, an antimalarial drug which had the greatest effect on vincristine uptake and relatively low host toxicity, exhibited potent therapeutic synergism in combination with vincristine in resistant leukemia-bearing mice.

Animals↗
PubMed1988

Deficiency of a 42-kilodalton protein in tumor-derived fibroblastic cells in neurofibromatosis.

Cell proteins obtained from cultured normal appearing skin and neurofibromas of neurofibromatosis patients, and normal skin of normal donors were compared by SDS-PAGE and isoelectric focusing analysis. Essentially, identical protein patterns were obtained for the pellet fractions of all the strains. The lysate fraction binding patterns were also similar to each other, but a deficiency of a 42-kilodalton protein with pI 4.3 was observed in the four tumor-derived cell strains examined. These results raise the possibility that tumor-derived fibroblastic cells are of the same cell origin as skin fibroblasts, and that the deficiency of a 42-kilodalton protein could be related to the tumorigenicity in neurofibromatosis.

Electrophoresis, Gel, Two-Dimensional↗