Self-renewal and differentiation of a basic fibroblast growth factor-dependent multipotent hematopoietic cell line derived from embryonic stem cells

Despite the accumulation of informat on on the origin of hematopoietic stem cells, it is still unclear how these cells are generated in ontogeny. Isolation of cell lines equivalent to early embryonic hematopoietic progenitor cells can be helpful. A multipotent hematopoietic progenitor cell line, A-6, was isolated from H-1 embryonic stem (ES) cells. The self-renewal of A-6 cells was supported by basic-fibroblast growth factor (b-FGF) and their differentiation into definitive erythroid cells, granulocytes and macrophages was induced after co-culture with ST-2 stromal cells. A-6 cells were positive for the surface markers of hematopoietic stem cell, c-kit, CD31, CD34, Flt3/Flk2, PgP-1, and HSA, but were negative for that of the differentiated cells. Reverse transcription-polymerase chain reaction analysis showed that A-6 cells produced mRNA from SCL/tal-1 and GATA-2 genes. Among various cytokines examined, on y stem cell factor (SCF) and Flt3/Flk2 ligand (FL) supported the proliferation of A-6 cells instead of b-FGF. The FL, as well as b-FGF, supported the self-renewal of A-6 cells, whereas SCF induced differentiation into myeloid cells. A-6 cells will be useful for the characterization of hematopoietic progenitor cells derived from ES cells and provide a model system to realize the control mechanisms between self-renewal and different ation of hematopoietic stem cells.

Upregulation of the elongation factor-1alpha gene by p53 in association with death of an erythroleukemic cell line

Genes upregulated by p53 were screened using an erythroleukemic cell line (1-2-3) that expresses only the temperature-sensitive p53 by the mRNA differential display method. One of the upregulated genes was identified as the elongation factor-1alpha (EF-1alpha) gene, an essential component of the eukaryotic translation apparatus. Three p53-responsive elements were found in the mouse EF-1alpha gene and in the corresponding human, rat, and frog genes. These elements conferred the capacity for induction by p53. EF-1alpha is also a microtubule-severing protein. Upon the temperature-shift, the cells developed the morphology and the localization of alpha-tubulin similar to those of the cells treated with vincristine, a drug that affects microtubules. The microtubule-severing associated with upregulation of EF-1alpha by p53 may be a cause of the cell death.

Up-regulation of cell cycle-associated genes by p53 in apoptosis of an erythroleukemic cell line

A murine erythroleukemic cell line (1-2-3) which expresses only the temperature-sensitive mutant p53 gene (Ala-to-Val substitution at codon 135) was established. When these cells were cultured at 32 degrees C, the growth rate was reduced significantly and DNA fragmentation, a typical character of apoptosis, was observed. In this process, p53 migrated from cytoplasm to nucleus and protein complexes binding to the p53-responsive element were detected in nuclear extracts of the cells cultured at 32 degrees C by gel-shift assay and transactivation from the p53-responsive element was detected. The expression of the p21 (waf1/cip1/sdi1), cyclin G and gadd45 genes was increased (about 3 to 4 fold that at 37 degrees C), when the cells were cultured at 32 degrees C. However, the expression of the bax gene was increased slightly (about 1.5 fold that at 37 degrees C) and no significant change was detected in expression of the mdm2 gene. No change in the amount of Fas antigen was observed by flow cytometric analysis. Transcripts of the bcl-2 and fasl gene were not detected in the cells both at 37 degrees C and 32 degrees C. These results suggest that up-regulation of the genes associated with the cell cycle and/or DNA replication, such as p21, cyclinG and gadd45 rather than bax, fas, fasl and bcl-2 may be important for induction of apoptosis of this erythroleukemic cell line by p53.

Genomic imprinting of the human serotonin-receptor (HTR2) gene involved in development of retinoblastoma

Epidemiological and genetic studies of retinoblastoma (RB) suggested that imprinted genes might be genetically linked to the RB gene. In this study, we found that the human serotonin-receptor, HTR2, gene, which had been mapped nearby the RB gene on chromosome 13, was expressed only in human fibroblasts with a maternal allele and not in cells without a maternal allele. The 5' genomic region of the human HTR2 gene was cloned by PCR-mediated method. Only the 5' region of the gene was methylated in cells with the maternal gene, and it was not methylated in cells without the maternal gene. A polymorphism of PvuII site of the gene was also found and useful for the segregation analysis in a family of a RB patient and for analysis of loss of heterozygosity on chromosome 13 in tumor and its parental origin. These results suggest that the human HTR2 gene might be affected by genomic imprinting and that exclusive expression of the maternal HTR2 gene may be associated with the delayed occurrence of RB, which had lost the maternal chromosome 13.

No significant changes in the expression of the fas,fasl,bcl-2 and bax genes in apoptosis of an erythroleukemic cell line by p53

A murine erythroleukemic cell line (1-2-3) which expresses only the temperature-sensitive mutant p53 gene (Ala-to-Val substitution at codon 135) was established. When these cells were cultured at 32 degrees C, the growth rate was reduced significantly and DNA fragmentation, a typical character of apoptosis, was observed. In this process, p53 migrated from cytoplasm to nucleus and protein complexes binding to the p53-responsive element were detected in nuclear extracts of the cells cultured at 32 degrees C by gel-shift assay and transactivation from the p53-responsive element was detected. The expression of the p21 (waf1/cip1/sdi1), cyclin G and gadd45 genes was increased (about 3- to 4-fold that at 37 degrees C), when the cells were cultured at 32 degrees C. However, no significant change was detected in expression of the mdm2, bax and fas genes. No change in the amount of Fas antigen was observed by flow cytometric analysis. Transcripts of the bcl-2 and fas1 gene were not detected in the cells either at 37 degrees C or 32 degrees C. These results suggest that other gene(s) than bax, fas, fas1 and bcl-2 may be important for induction of apoptosis of this erythroleukemic cell line by p53.

A C3H strain-specific allele (alpha va126) of the murine alpha-globin gene newly detected by UT-PAGE and RT-PCR-SSCP analysis

An extra band. distinct from the well-characterized globin chains (alpha, beta-maj, beta-min, beta-s), was detected in an adult erythrocyte sample of the C3H strain by urea triton polyacrylamide gel electrophoresis (UT-PAGE) analysis. The extra band was recognized by an antibody against the alpha-globin chain by Western blot analysis. Reverse transcription, polymerase chain reaction and single strand conformation polymorphism (RT-PCR-SSCP) analysis and direct sequencing analysis of cDNA of the alpha-globin gene revealed a nucleotide substitution (GGA to GTA) corresponding to an amino acid substitution (Gly to Val) at codon 26 in the alpha-globin gene only in the erythrocyte sample of the C3H strain. Polypeptides generated by in vitro translation from the alpha-globin gene with the nucleotide substitution at codon 26 (alpha Val26) had the same mobility as that of the extra band of the C3H strain in UT-PAGE. These results suggest that the substitution GGA (Gly) to GTA (Val) at codon 26 of the murine alpha-globin gene may directly affect the mobility of alpha-globin in UT-PAGE and the base substitution may be a C3H strain-specific polymorphism.

A follistatin-like gene, mac25, may act as a growth suppressor of osteosarcoma cells

mac25, a retinoic acid-inducible gene that is expressed at high levels in senescent epithelial cells, was initially cloned as a gene that is differentially expressed in meningioma. Although the homology of its product with members of family of insulin-like growth factor-binding proteins was suggested, the product also exhibits strong homology to follistatin, an activin-binding protein. However, a domain corresponding to the carboxyl terminus of follistatin is not found in mac25. The carboxyl-terminally truncated form of follistatin, generated by alternative splicing, has stronger activin-binding activity than the complete form. This result suggests that mac25 might act as an activated follistatin. Clonal growth of a p53-deficient osteosarcoma cell line was strongly inhibited when the murine mac25 gene, as well as the p53 gene, was introduced. Resembling activins that belong to the transforming growth factor-beta (TGF-beta) superfamily, mac25 and p53 might associate with similar but distinct targets, namely cyclin-dependent kinase inhibitors. However, there is no evidence for compensation of p53 function by mac25 in the development of p53-deficient mice, as judged from the pattern of expression of mac25 in mice. mac25 might act as a tumor suppressor, modulating signaling of the TGF-beta family, as does alpha-inhibin.

Repression of p53-dependent sequence-specific transactivation by MEF2c

Lambda ZAP cDNA library constructed from spleen of a p53-deficient mouse was screened by South-Western technique using Fragment A, a DNA sequence that p53 specifically binds to, as a probe. One (clone 2) of six clones isolated was identical to MEF2c, a MADS-family transcription factor. Transcripts of the mef2c gene was also detected in spleen where the expression has not been reported so far. Isolated clones except clone 2 had a growth-suppression activity on p53-deficient osteosarcoma cell line (Saos II). Clone 2 repressed the transactivation from Fragment A by p53, suggesting that MEF2c may act as a negative regulator of p53-responsive element.

[A case of successful treatment of chronic sternal osteomyelitis and mediastinitis after ascending aorta and hemiarch reconstruction]

Mediastinitis is one of severe and fatal complications after cardiac surgery, especially in the presence of a prosthetic graft. A 70-year-old male, who was suffered from chronic sternal osteomyelitis and mediastinitis after ascending aorta and hemiarch reconstruction was reported. He developed high fever and leucocytosis on the 16th postoperative day. Wound culture was positive for Grampositive organisms. He was diagnosed as having sternal osteomyelitis and mediastinitis and treated by sternal bone debridement and irrigation with dilute povidone iodine solution with no effects. Total excision of the infected sternum, irrigation with non-diluted solution of povidone iodine and omental transfer were performed successfully. The literature regarding omental transfer for mediastinitis and infected prosthetic grafts was briefly reviewed.

A mouse erythroleukemia cell line possessing friend spleen focus-forming virus gp55 transgene and temperature-sensitive mutant p53 gene

Two different erythroleukemia cell lines have been established from the splenic lesions of transgenic mice possessing the Friend spleen focus-forming virus (F-SFFV) gp55 gene. One showed a near-diploid karyotype and a temperature-sensitive (ts) p53 mutation, and the other, a hyper-triploid karyotype with double p53 mutations found by single-strand conformation polymorphism (SSCP) analysis. The cell lines both retained No.11 chromosomes on which p53 genes are localized. Another p53 allele in the cell line with the ts-p53 mutation appeared intact in the SSCP analysis of the genomic exon 5. The cells with the ts-mutant p53 gene showed no apparent change with temperature shift in their growth or dimethylsulfoxide-induced differentiation, although the wild-type p53 gene on the other allele was not expressing. This ts-p53Val-135 gene made p53-deficient fibroblasts anchorage-independent at 37 degrees C but not at 32 degrees C. This non-virus-producing, mouse erythroleukemia cell line will be useful for the study of mutated p53 function during the induction of erythrodifferentiation or apoptotic change.

Parthenogenetic activation of oocytes in c-mos-deficient mice

In Xenopus the c-mos proto-oncogene product (Mos) is essential for the initiation of oocyte maturation, for the progression from meiosis I to meiosis II and for the second meiotic metaphase arrest, acting as an essential component of the cytostatic factor CSF. Its function in mouse oocytes is unclear, however, as is the biological significance of c-mos mRNA expression in testes and several somatic tissues. We have generated c-mos-deficient mice by gene targeting in embryonic stem cells. These mice grew at the same rate as their wild-type counterparts and reproduction was normal in the males, but the fertility of the females was very low. The c-mos-deficient female mice developed ovarian teratomas at a high frequency. Oocytes from these females matured to the second meiotic metaphase both in vivo and in vitro, but were activated without fertilization. The results indicate that in mice Mos plays a role in the second meiotic metaphase arrest, but does not seem to be essential for the initiation of oocyte maturation, spermatogenesis or somatic cell cycle.

[A case of a right subclavian arterial aneurysm associated with the aortic arch anomaly in childhood]

Aneurysms in the subclavian arteries are extremely rare in childhood. A 7-year-old boy was admitted with hoarseness and abnormal shadow in the chest film. Radiologic studies demonstrated a right subclavian arterial aneurysm associated with the aortic arch anomaly. Proximal and distal ligation of the subclavian arterial aneurysm and reconstruction of blood flow by an aorto-subclavian bypass using a 5 mm GORE-TEX prosthetic graft were performed through a standard median sternotomy incision with extension to the right supraclavicular space. The postoperative course was uneventful and he was discharged in 3 weeks. The literature of the subclavian arterial aneurysm was briefly reviewed.

Histopathological findings in the biopsied muscle of a juvenile type III glycogenosis

We report a case of juvenile type III glycogenosis that was confirmed by histopathological and biochemical studies. The histopathological findings consisted of vacuoles, periodic acid-Schiff positive materials, type 2B fiber deficiency, mildly positive acid phosphatase reaction and intensely positive non-specific esterase reaction. It is suggested that the enzyme reactions may be related to membrane-bound sacs containing glycogen.

Increased uptake sites for serotonin and dopamine with decreased S2 serotonin receptors in microencephalic rat brain

Methylazoxymethanol (MAM)-induced cerebral hypoplasia resulted in a significant increase in densities of both serotonin uptake sites in frontal cortex and dopamine uptake sites in striatum, suggesting serotonergic and dopaminergic axons terminals were compressed in the smaller brain volumes. The density of S2 serotonin receptors in MAM-lesioned frontal cortex was decreased probably due to down-regulation, while densities of D1 and D2 dopamine receptors in striatum were identical between MAM-lesioned rats and control rats.

Env-derived gp55 gene of Friend spleen focus-forming virus specifically induces neoplastic proliferation of erythroid progenitor cells

A group of retroviruses carrying truncated viral genes has recently been suggested as the cause of new patterns of diseases. One such virus is the replication defective component of the Friend murine leukemia virus (F-MuLV) complex, called Friend spleen focus forming virus (F-SFFV). This virus induces erythroblastosis, and a virion envelope-related glycoprotein, gp55, encoded by F-SFFV has been suggested as the pathogenic gene. The role of the gp55 gene is, however, yet unclear in the apparently multistep erythroleukemogenesis. By separately producing transgenic mice harboring the whole F-SFFV DNA, the gp55 gene alone under the control of the retroviral long terminal repeat (LTR) and the gp55 gene under the control of cytoplasmic beta actin transcriptional regulatory unit, we show here that the gp55 gene is capable of inducing neoplastic proliferation of erythroid progenitor cells specifically in the absence of helper virus and other F-SFFV sequences. Under the control of the viral LTR the gp55 expression was detected only in leukemic tissues, but under the control of cytoplasmic beta-actin regulatory sequences, the gp55 was also expressed in a variety of normal tissues including preleukemic normal spleens. The development of erythroleukemia was suppressed under the genetic background of C57B1/6 mouse (resistant to F-MuLV; Fv-2rr), and required additional events even under the background of DDD mouse (susceptible to F-MuLV; Fv-2ss). The p53 and Spi-1 genes were frequently aberrant in transplanted tumors and cell lines derived from them, but were not in primary leukemic spleens.

[A case of rapidly developed constrictive pericarditis following acute non-specific pericarditis]

A case of constrictive pericarditis which developed within one month after the onset of acute pericarditis was presented. A 3-year-old boy was admitted to our hospital suffering from dyspnea. Pericardectomy was performed 3 weeks after the pericardial drainage. His echocardiograms revealed the progressive thickening of the pericardium, severely restricted ventricular motion in both systole and diastole and paradoxical motion of the interventricular septum. Echocardiography at close intervals is useful for making the diagnosis and decision of the surgical intervention of rapidly developed constrictive pericarditis.

[A case of leiomyosarcoma of the inferior vena cava]

Primary leiomyosarcoma of the inferior vena cava is rare and fatal. A 15-year-old female was admitted with the diagnosis of the right atrial myxoma associated with the Budd-Chiari syndrome. The tumor of the IVC was unresectable, although the right atrial tumor extended from the IVC was extirpated. Pathological examination of the tumor revealed a leiomyosarcoma. She was hemodynamically improved immediately after the operation. But she was expired due to the hepatic failure 9 days postoperatively. No autopsy was obtained. The literature regarding with leiomyosarcoma of the IVC was briefly reviewed.

Brain changes in rats induced by prenatal injection of methylazoxymethanol

Various doses (0, 1, 5, 10, 15, 20, or 25 mg/kg) of methylazoxymethanol acetate (MAM), a potent alkylating agent, were injected singly into pregnant rats intraperitoneally on day 15 of gestation. Relationships between brain weights and neurochemical changes in the cerebral hemispheres (CHs; cerebral cortex and subjacent white matter, hippocampus, amygdala) and remainder of the brain (BGDM; basal ganglia, diencephalon, and mesencephalon) were examined at 60 days of age in offspring; varying degrees of microencephaly were observed. Dose-dependent reductions in the weights of CH and BGDM were observed. Reductions in total DNA content positively correlated with decreases in brain weights also observed. Dose-dependent elevations of noradrenaline (NA) and dopamine (DA) were observed in CH at MAM levels 10 mg/kg and above; dose-dependent elevations of 5-hydroxytryptamine (5-HT) were observed at 15 mg/kg and above; and in BGDM at 20 mg/kg and above dose-dependent elevations for NA and 5-HT were observed; dose-dependent elevations at 15 mg/kg and above were observed for DA. Monoamine concentrations were negatively correlated with brain weights or total DNA contents. NA and DA concentrations increased to the extent of approximately 1.3 times of control at a time when an 18% loss of CH weight was noted in animals treated with 10 mg/kg MAM. It is suggested that the above variables might be appropriately sensitive neurochemical markers for detecting minor developmental anomalies in the brain.