Browsing by Subject "Proto-oncogene"

Now showing 1 - 4 of 4
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    Distribution and expression of mRNAs for the proto-oncogenes c-fos and c-jun in bone cells in vivo
    (Murcia : F. Hernández, 1998) Oyama, M.; Chiba, J.; Kato, Y.; Igarashi, N.; Yoshida, M.; Ishigami, M.; Sugawara, S.; Kobayashi, M.
    In this study we assessed the expression and localization of the proto-oncogenes c-fos and c-jun in normal bone so as to gain more insight into the role of these proto-oncogenes in bone tissue. Femurs of 4-weekold rats were examined by non-radioactive in situ hybridization. cDNA probes for c-fos- and c-jun-labeled digoxygenin were produced by Polymerase Chain Reaction (PCR). C-fos and c-jun exhibited similar distribution in growth plate and bone tissue. Expression of c-fos and cjun mRNAs in growth plate was observed in the proliferative zone and partly in the upper layer of the hypertrophic zone. In spongy bone, high expression of cfos and c-jun mRNAs was observed in the osteoblast cytoplasm. However, there was little expression in bone lining cells. In the bony trabeculae, slight expression of c-fos and c-jun was observed in the premature osteocytes situated close to the bone surface, but no expression was detected in osteocytes that possessed relatively large lacunae in the center of the trabeculae. C-fos and c-jun were also slightly expressed in osteoclasts. These data strongly suggest that c-fos and c-jun are involved in regulating chondrocyte proliferation as immediate early genes, and may also be involved in the gene expression of bone matrix proteins as transcription factor (M-1) in vivo. In addition, the fact that strong expression was observed in osteoblasts but hardly any expression at all in bone lining cells seems to suggest that these genes are also involved in osteoblast activation.
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    Expression of the proto-oncogene c-fos and the immunolocalization of c-fos, phosphorylated c-fos and estrogen receptor beta in the human testis
    (Murcia : F. Hernández, 2009) Araújo, Fabiano C.; Oliveira, Cleida A.; Reis, Augusto E.; Del Puerto, Helen L.; Martins, Almir S.; Reis, Fernando M.
    Spermatogenesis is under the control of a complex endocrine and paracrine system, including estrogen receptor (ER) signaling. In many target cells, ER promotes the transcription of c-fos and other protooncogenes to regulate cell growth and differentiation. Thus, in this study we evaluated the expression of the proto-oncogene c-fos and the immunolocalization of cfos, phosphorylated c-fos and ERbeta proteins in the human testis. Testis tissue samples were obtained from 12 men undergoing orchiectomy as adjuvant treatment for prostate cancer, and were stained by immunohistochemistry for c-fos, phosphorylated c-fos and ERbeta localization. Both forms of c-fos proteins were immunoreactive, mainly in germ cells (spermatogonia, spermatocytes and spermatids) and Sertoli cells, while ERbeta was primarily present in somatic cells (Leydig, Sertoli and myofibrillar cells). In addition, testicular biopsies obtained from infertile men with obstructive azoospermia/normal spermatogenesis (n=8) or non-obstructive azoospermia/severely impaired spermatogenesis (n=12) were evaluated for c-fos and ERbeta mRNA levels using real time polymerase chain reaction. The expression of c-fos mRNA was significantly lower (fold change = 0.08, p<0.05) whereas that of ERbeta mRNA was higher (fold change = 9.43, p<0.05) in the testis of men with non-obstructive azoospermia compared to those with obstructive azoospermia. These findings suggest a complex interrelation between estrogen signaling and c-fos transcriptional activity within the human testis, with the increase of ERbeta mRNA being putatively a compensatory mechanism for lower c-fos expression in infertile men with damaged spermatogenesis.
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    Localization and functions of steroid hormone receptors
    (Murcia : F. Hernández, 1998) Yamashita, S.
    This review focuses on the subcellular localization of steroid hormone receptors (SHRs), taking into account the technical problems of immunohistochemistry and the characteristics of nuclear localization signals (NLSs) of each receptor, on the interaction between SHKs and cellular components, and on the possible roles of sex SHRs in the reproductive organs. It is concluded that SHRs are basically localized in the nucleus, regardless of hormonal status, and that considerable amounts of unliganded SHRs may be present in the cytoplasm of target cells in exceptional cases. Most immunohistochemical results that demonstrate nuclear translocation of liganded SHRs seem to be responsible for insufficient fixation. Immunoelectron microscopy shows that SHRs associate with the chromatin in absence or presence of hormones and that intranuclear translocation of liganded SHRs from the condensed chromatin to euchromatin which observed in some cell types, may be a passive process caused by a consequence of conformational changes in the chromatin binding receptors. Histochemical data suggest that the nuclear matrix (NM) is not a main binding site of liganded SHRs in the nucleus. The artificial formation of intermolecular disulfide bonds during NM preparation presumably causes the entrapment of liganded SHRs into the fraction. It seems that heat shock protein 90 (hsp90) does not form stable complexes with unliganded receptors in vivo, and it interacts with SHRs transiently cooperating with other heat shock proteins as a chaperone that helps folding of newly synthesized and refolding of denatured receptors. Estrogens transiently induce a number of nuclear protooncogenes, such as c-fos and c-jun family proteins, which act as transcription factors through estrogen receptor (ER) system in the endometrial epithelium of mature and immature rodents. Therefore, it is suggested that the changes in concentrations of these gene products trigger the proliferation and differentiation of uterine epithelium. In addition, ER system, not only in stroma cells but in the epithelia1 cells appears to participate in the growth response and abnormalities of epithelium elicited by the exogenous estrogen treatment at the neonatal period.
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    Molecular biology of glioma tumorigenesis
    (Murcia : F. Hernández, 2003) Ware, M.L.; Berger, M.S.; Binder, D.K.
    Gliomas are the most common intracranial malignant tumors in humans, and high-grade gliomas in particular pose a unique challenge due to their propensity for proliferation and tissue invasion. Our understanding of glioma oncogenesis, proliferation, and invasion has been greatly advanced in the past 10 years as researchers have gained a better understanding of the molecular biology of these tumors. This article highlights glioma histopathology, as well as cytogenetic and molecular alterations associated with the pathogenesis of human gliomas. It is hoped that better understanding of the molecular pathogenesis of gliomas will improve tumor classification as well as lead to novel targets for therapy and prognostic markers.