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707 Differential expression of fos family and jun family proto-oncogenes in the rat brain after immobilization stress
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705
THE mouse-musashi GENE ENCODING NERVOUS-TISSUE SPECIFIC RNA BINDING
PROTEIN. SHIN-ICHI SAKAKIBARA, }tIDEYUKI OKANO, AND KATSUHIKO MIKOSHIBA, Department of Molecular Neurobiology, The Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai Minato-ku, Tokyo 108, Japan. We could isolate the mouse-musashi gene, which is the mouse homologue of Drosophila musashigene encoding a nervous-tissue specific RNA-binding protein, required for cell fate decision in sensory cells. Structurally, both Drosophila musashi and,-nouse-musashi have two tandem RRM (RNA-recognition motif) and these two gene showed 60% amino acid identity in the RRM region. Northern blot analysis reveled that the mouse-musashiis atsoexpressed in the nervous-tissue specific manner in mice. We characterized the immunolocalization of the mouse-musashiusing its specific antisera raised against bacterially-expressed mouse-musashigene product. Immunoblot analysis detected several mouse-musashi gene products around 36 kD, which may have resulted from the alternative splicing of the gene. The immunohistochemical characterization of its developmental expression indicated that its expression is specific to the nervous-system and that it is enriched in the mitotic active neuronal precursor ceils. We found that the mouse-musashiis co-localized with the PCNA (prolipherating cell nuclear antigen) in the mitotic active neural tissues, such as the ventricular zone of the embryonic neural tube, the EGL of the cerebellum and the migratory pathway between the angle of lateral ventricle and olfactory bulb. Such an expression pattern is consistent with our hypothesis that mouse-musashi is required for the cell fate decisions of undifferentiated neural precursor cells by regulating downstream target post-transcriptionally.
706
M Y C PROTEIN EXPRESSION IN DEVELOPING NEURONS OF THE RAT C E R E B E L L U M . TETSURO HORIKOSHI 1, MANABU SAKAKIBARA 1, MEGUMI TAKAHASHI2, SATOSHI TOYOSHIMA3, HIROSHI TAKAGI4, YOSHIHISA KUDO 5 AND TOHRU YOSHIOKA4, IDept. of Biol. Sci. and TCch., Sch. of Hi~h-Tech., Tokai University, 317 Nishino, Numazu 410-03, 2Sch. of Med., Yokohama City University, Yokohama 236, 3japan Tobacco Inc Pharmac. Basic Res. Lab., Yokohama 236, 4Lab. of Mol, Neurobiol., Sch. of Human Sci., Waseda University, Tokorozawa 359 and 5Mitsubishi Kasei Institute of Life Sci., Machida 192, Japan Recent study revealed that the m)v oncogene and the MYC protein in cytoplasm plays an important role in the differentiation but detail of its function is still unclear at present. In order to elucidate the physiological function of MYC protein, we examined the change in the expression of c-myc gene and MYC protein compared with the change in immunostaining by anti PIP2 antibody and in Ca imaging of rat cerebellar slice with the postnatal date. Interestingly, the intracellular Ca mobilization by the stimulation of quisqualate was extremely poor in Purkinje dendrite on PND 10, while that on PND 14 was enormously increased. Purkinje dendrites on PND 10 was found to be stained well by anti-PIP2 antibody and also by anti-MYC antibody, whereas the dendrites was poorly on PND 14. These results can be explained ifMYC protein is a phosphatase inhibitor because phosphorylated phospholipase C can not produce IP3 and phosphorylated IP3 receptor can not mobilize intracellular Ca. Considering some other data obtained in this experiment, MYC protein probably keep IP3 receptor to be phosphorylated and block IP3 induced Ca release from Ca store.
DIFFERENTIAL EXPRESSION OF FOS FAMILY AND J U N FAMILY PROTO-ONCOGENES IN THE RAT BRAIN AFTER IMMOBILIZATION STRESS EMIKO SENBA, SANTA UMEMOTO, YOSHINORI KAWAI and KOICHI NOGUCHI. Dept. of Anatomy & Neurobioloqy, Wakayama Medical College, 27 Kyuban-cho, Wakayama City, 640, Japan
707
Activation of fos family and jun family proto-oncogenes is linked to genomic events which control long-term changes in neurons. The effect of immobilization stress on the expression of c-fos, fos B, c-jun, jun B and jun D mRNAs in the rat brain were investigated using in situ hybridization histochemistry. Adult male Sprague-Dawley rats (150-200g) were fixed on their backs on a board for 7, 15, 30, 60 min, and killed. In control rats, e-jun and jun D mRNAS were expressed in various brain regions, while c-fos, fos B and jun B mRNAs were not observed. After 7 min of immobilization, c-fos and jun B mRNA levels were remarkably increased in the cortex, hippocampus (CAI-CA2), lateral septum (LS), hypothalamic paraventricular nucleus, medial amygdaloid nucleus (Me) and locus coeruleus (LC). The levels of these mRNAs peaked after 15-30 min of immobilization and then declined. The expression of fos B mRNA tended to de~ay. Jun D m R N A was constitutively expressed and did not respond to the stimulation, while an increase of c-jun m R N A was observed in certain brain regions, such as the LS, Me and LC in response to immobilization. These findings suggest that each members of fos family and jun family proto-oncogenes are differentially regulated in various brain regions.
705
THE mouse-musashi GENE ENCODING NERVOUS-TISSUE SPECIFIC RNA BINDING
PROTEIN. SHIN-ICHI SAKAKIBARA, }tIDEYUKI OKANO, AND KATSUHIKO MIKOSHIBA, Department of Molecular Neurobiology, The Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai Minato-ku, Tokyo 108, Japan. We could isolate the mouse-musashi gene, which is the mouse homologue of Drosophila musashigene encoding a nervous-tissue specific RNA-binding protein, required for cell fate decision in sensory cells. Structurally, both Drosophila musashi and,-nouse-musashi have two tandem RRM (RNA-recognition motif) and these two gene showed 60% amino acid identity in the RRM region. Northern blot analysis reveled that the mouse-musashiis atsoexpressed in the nervous-tissue specific manner in mice. We characterized the immunolocalization of the mouse-musashiusing its specific antisera raised against bacterially-expressed mouse-musashigene product. Immunoblot analysis detected several mouse-musashi gene products around 36 kD, which may have resulted from the alternative splicing of the gene. The immunohistochemical characterization of its developmental expression indicated that its expression is specific to the nervous-system and that it is enriched in the mitotic active neuronal precursor ceils. We found that the mouse-musashiis co-localized with the PCNA (prolipherating cell nuclear antigen) in the mitotic active neural tissues, such as the ventricular zone of the embryonic neural tube, the EGL of the cerebellum and the migratory pathway between the angle of lateral ventricle and olfactory bulb. Such an expression pattern is consistent with our hypothesis that mouse-musashi is required for the cell fate decisions of undifferentiated neural precursor cells by regulating downstream target post-transcriptionally.
706
M Y C PROTEIN EXPRESSION IN DEVELOPING NEURONS OF THE RAT C E R E B E L L U M . TETSURO HORIKOSHI 1, MANABU SAKAKIBARA 1, MEGUMI TAKAHASHI2, SATOSHI TOYOSHIMA3, HIROSHI TAKAGI4, YOSHIHISA KUDO 5 AND TOHRU YOSHIOKA4, IDept. of Biol. Sci. and TCch., Sch. of Hi~h-Tech., Tokai University, 317 Nishino, Numazu 410-03, 2Sch. of Med., Yokohama City University, Yokohama 236, 3japan Tobacco Inc Pharmac. Basic Res. Lab., Yokohama 236, 4Lab. of Mol, Neurobiol., Sch. of Human Sci., Waseda University, Tokorozawa 359 and 5Mitsubishi Kasei Institute of Life Sci., Machida 192, Japan Recent study revealed that the m)v oncogene and the MYC protein in cytoplasm plays an important role in the differentiation but detail of its function is still unclear at present. In order to elucidate the physiological function of MYC protein, we examined the change in the expression of c-myc gene and MYC protein compared with the change in immunostaining by anti PIP2 antibody and in Ca imaging of rat cerebellar slice with the postnatal date. Interestingly, the intracellular Ca mobilization by the stimulation of quisqualate was extremely poor in Purkinje dendrite on PND 10, while that on PND 14 was enormously increased. Purkinje dendrites on PND 10 was found to be stained well by anti-PIP2 antibody and also by anti-MYC antibody, whereas the dendrites was poorly on PND 14. These results can be explained ifMYC protein is a phosphatase inhibitor because phosphorylated phospholipase C can not produce IP3 and phosphorylated IP3 receptor can not mobilize intracellular Ca. Considering some other data obtained in this experiment, MYC protein probably keep IP3 receptor to be phosphorylated and block IP3 induced Ca release from Ca store.
DIFFERENTIAL EXPRESSION OF FOS FAMILY AND J U N FAMILY PROTO-ONCOGENES IN THE RAT BRAIN AFTER IMMOBILIZATION STRESS EMIKO SENBA, SANTA UMEMOTO, YOSHINORI KAWAI and KOICHI NOGUCHI. Dept. of Anatomy & Neurobioloqy, Wakayama Medical College, 27 Kyuban-cho, Wakayama City, 640, Japan
707
Activation of fos family and jun family proto-oncogenes is linked to genomic events which control long-term changes in neurons. The effect of immobilization stress on the expression of c-fos, fos B, c-jun, jun B and jun D mRNAs in the rat brain were investigated using in situ hybridization histochemistry. Adult male Sprague-Dawley rats (150-200g) were fixed on their backs on a board for 7, 15, 30, 60 min, and killed. In control rats, e-jun and jun D mRNAS were expressed in various brain regions, while c-fos, fos B and jun B mRNAs were not observed. After 7 min of immobilization, c-fos and jun B mRNA levels were remarkably increased in the cortex, hippocampus (CAI-CA2), lateral septum (LS), hypothalamic paraventricular nucleus, medial amygdaloid nucleus (Me) and locus coeruleus (LC). The levels of these mRNAs peaked after 15-30 min of immobilization and then declined. The expression of fos B mRNA tended to de~ay. Jun D m R N A was constitutively expressed and did not respond to the stimulation, while an increase of c-jun m R N A was observed in certain brain regions, such as the LS, Me and LC in response to immobilization. These findings suggest that each members of fos family and jun family proto-oncogenes are differentially regulated in various brain regions.