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Physiology and Pharmacology and
Medicine, University of Western Ontario, Canada
Children’s Health Research Institute, London, Ontario, Canada
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Physiology and Pharmacology and
Medicine, University of Western Ontario, Canada
Children’s Health Research Institute, London, Ontario, Canada
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Physiology and Pharmacology and
Medicine, University of Western Ontario, Canada
Children’s Health Research Institute, London, Ontario, Canada
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Physiology and Pharmacology and
Medicine, University of Western Ontario, Canada
Children’s Health Research Institute, London, Ontario, Canada
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Physiology and Pharmacology and
Medicine, University of Western Ontario, Canada
Children’s Health Research Institute, London, Ontario, Canada
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pancreatic precursor cells into either acinar, islet or duct cells is apparent morphologically ( Slack 1995 ). The differentiation of these cells is regulated by the correct temporal and spatial expression of a series of transcription factors that direct
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Department of Biomedical Science and Technology, Department of Pathology and Immunology, Howard Hughes Medical Institute, Laboratory of Reproductive Biology and Infertility, RCTC, IBST, Konkuk University, 1 Hwayang-Dong, Kwangjin-Gu, Seoul 143-701, South Korea
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( Hagglund et al . 1999 ). Etv4 transcription factors belong to superfamily of E26 transformation-specific (Ets) transcription factors. The Ets transcription factors regulate expression of target genes by binding to a ∼10 bp element in the promoters of
School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK
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School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK
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School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK
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School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK
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School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK
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transcription factor, signal transduction, and metabolic enzyme gene expression. We have used 10 mM l -glutamine in the work reported in this paper, so as to saturate l -glutamine transport and allow comparison of our results with previously published studies
Group on Hormones and Signal Transduction, German Cancer Research Center, Heidelberg D-69120, Germany
Laboratory of Genomic Applications, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel
Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA
Department of Oncological Surgery, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel
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Group on Hormones and Signal Transduction, German Cancer Research Center, Heidelberg D-69120, Germany
Laboratory of Genomic Applications, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel
Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA
Department of Oncological Surgery, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel
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Group on Hormones and Signal Transduction, German Cancer Research Center, Heidelberg D-69120, Germany
Laboratory of Genomic Applications, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel
Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA
Department of Oncological Surgery, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel
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Group on Hormones and Signal Transduction, German Cancer Research Center, Heidelberg D-69120, Germany
Laboratory of Genomic Applications, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel
Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA
Department of Oncological Surgery, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel
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Group on Hormones and Signal Transduction, German Cancer Research Center, Heidelberg D-69120, Germany
Laboratory of Genomic Applications, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel
Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA
Department of Oncological Surgery, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel
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Group on Hormones and Signal Transduction, German Cancer Research Center, Heidelberg D-69120, Germany
Laboratory of Genomic Applications, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel
Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA
Department of Oncological Surgery, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel
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Group on Hormones and Signal Transduction, German Cancer Research Center, Heidelberg D-69120, Germany
Laboratory of Genomic Applications, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel
Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA
Department of Oncological Surgery, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel
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flanking the transcription start site is extremely GC-rich, and contains numerous potential binding sites for transcription factor Sp1, a zinc-finger-containing nuclear protein that has been shown to strongly transactivate the IGF-IR promoter ( Beitner
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pyruvate kinase C and glucose transporter GLUT-2 ( Valera et al. 1993 ), as well as the transcription factors c-fos and c-jun ( Gronowski & Rotwein 1995 ). More recent gene expression studies employing the microarray technology have identified many more
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Androgenic status affects rat preadipocyte adipose conversion from two deep intra-abdominal (epididymal and perirenal) fat depots differently. The aim of this study was to establish whether these site-specific alterations of adipogenesis are related to altered expressions of the transcriptional factors regulating proliferation and differentiation of preadipocytes, c-myc and CCAAT/enhancer binding proteins (C/EBPs: C/EBPalpha and beta). The increased proliferation of epididymal and perirenal preadipocytes from castrated rats was not linked to variations in c-myc mRNA and protein levels. The expression of the early marker of adipogenesis, lipoprotein lipase (LPL), was decreased by androgenic deprivation in epididymal cells but remained insensitive to the androgenic status in perirenal preadipocytes. In contrast, LPL expression increased in subcutaneous preadipocytes from castrated rats, an effect which was partly corrected by testosterone treatment. Expression of C/EBPbeta was unaffected by androgenic status whatever the anatomical origin of the preadipocytes. In contrast, the mRNA and protein levels of C/EBPalpha were greatly decreased by androgenic deprivation in epididymal cells, an alteration which could not be corrected by in vivo testosterone administration. Altogether these results demonstrated that in preadipocytes androgenic deprivation affects site-specifically the expression of LPL, an early marker of adipogenesis and of C/EBPalpha, a master regulator of adipogenesis. These observations contribute to an explanation of why castration induces defective adipose conversion in rat epididymal preadipocytes specifically.
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A prominent functional change during differentiation of lutein cells from follicular thecal and granulosa cells is an enhanced production and secretion of progestins. The regulation of this process is not fully understood but may be associated with the expression of transcription factors which activate genes, products of which are involved in pathways of the cholesterol and lipid metabolism. As peroxisome proliferator-activated receptors (PPARs) play a role in both pathways, we were interested in the expression of PPARgamma, a PPAR form which is involved in adipogenic differentiation. First, we were able to show the expression of PPARgamma in bovine lutein cells (day 12 of the ovarian cycle) at the mRNA and protein level by imaging, flow cytometry and blot analysis, and secondly a role of PPARgamma in the secretion of progesterone. The cells (24 h culture) responded dose dependently by increasing progesterone secretion (up to 1.5-fold of the basal level) to an endogenous ligand of PPARgamma, 15-deoxy-delta12,14 prostaglandin J2 (15-dPGJ2) and to the thiazolidinedione ciglitizone. Aurintricarboxylic acid (ATA) was found to reduce the intracellular PPARgamma level and to promote cell cycle progress, indicating that ATA can be used as a tool for experimental changes of PPARgamma proteins in intact cells and for studying the physiological consequences. The ATA-mediated decrease of PPARgamma was accompanied by reduced progesterone production and a progression of the cell cycle, suggesting a function of PPARgamma in both processes. The response to ATA was abrogated by a high dose (>490 nM) of 15-dPGJ2, suggesting that 15-dPGJ2 exerts its effect on steroidogenic activity via PPARgamma and that the 15-dPGJ2-PPARgamma system plays a role in the maintenance of a differentiated quiescent stage in lutein cells.
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Abstract
The pituitary gland of the rdw rat (gene symbol: rdw) with hereditary dwarfism expresses 30–100 times less GH and prolactin (PRL) mRNA than normal controls. To clarify the features of rdw rats, TSH and the pituitary-specific transcription factor Pit-1, which is involved not only in the gene expression of GH and PRL but in somatotroph, lactotroph and thyrotroph development as well, were examined. The rdw pituitary contained about seven times more TSHβ mRNA than the normal control, whereas Pit-1 mRNA expression in rdw and control was the same. Nucleotide sequencing of PCR-amplified Pit-1 cDNA indicated that the deduced amino acid sequence of rdw Pit-1 was identical with that of the normal rat. Using an antibody against rat Pit-1 protein produced in E. coli, Western blotting analysis demonstrated the presence of the same amount of Pit-1 protein in rdw and normal rat pituitaries. The distribution of Pit-1-positive cells in the anterior pituitary was essentially the same in rdw and normal rats. It follows from these findings that the defective gene in the rdw rat is unrelated to the Pit-1 gene and the normal quantity of Pit-1 protein is insufficient to produce normal amounts of GH and PRL in the rdw pituitary. These and previous results suggest that the reduction in GH and PRL production in the rdw pituitary might be due to that in thyroid hormone production.
Journal of Endocrinology (1994) 143, 479–487
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Abstract
Scleraxis is a recently identified transcription factor with a basic helix-loop-helix motif, which is expressed in sclerotome during embryonic development. We have examined the expression of scleraxis mRNA in rat osteoblastic cells and found that the scleraxis gene was expressed as a 1·2 kb mRNA species in osteoblastic osteosarcoma ROS 17/2·8 cells. The scleraxis mRNA expression was enhanced by type-β transforming growth factor (TGFβ) treatment. The TGFβ effect was observed in a dosedependent manner starting at 0·2 ng/ml and saturating at 2 ng/ml. The effect was time-dependent and was first observed within 12 h and peaked at 24 h. The TGFβ effect was blocked by cycloheximide, while no effect on scleraxis mRNA stability was observed. TGFβ treatment enhanced scleraxis-E box (Scx-E) binding activity in the nuclear extracts of ROS17/2·8 cells. Furthermore, TGFβ enhanced transcriptional activity of the CAT constructs which contain the Scx-E box sequence. TGFβ treatment also enhanced scleraxis gene expression in osteoblastenriched cells derived from primary rat calvaria. These findings indicated for the first time that the novel helixloop-helix type transcription factor (scleraxis) mRNA is expressed in osteoblasts and its expression is regulated by TGFβ.
Journal of Endocrinology (1996) 151, 491–499
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Abstract
The mutant rat thyroid cell line FRTL-5/TA, isolated from a non-functional tumour which originated spontaneously from wild-type FRTL-5 cells, shows autonomous TSH-independent growth and loss of the thyroid-specific phenotype, lacking thyroid-specific expression of thyroglobulin (Tg) and thyroid peroxidase (TPO) genes. To investigate the role of the transcription factors Pax-8 and thyroid transcription factor-1 (TTF-1) in rat thyroid tumorigenesis, RNA expression of these two thyroid-specific nuclear factors was measured in FRTL-5/TA tumour cells and compared with the expression in wild-type FRTL-5 cells. TTF-1 gene expression was similar to that in wild-type FRTL-5, and showed a similar down-regulation after stimulation with TSH. The finding suggested normal TTF-1 mRNA and protein expression in both cell lines. By contrast, Pax-8 mRNA transcript signal was markedly reduced in FRTL-5/TA cells, reaching levels as low as 8% of the normal, basal level in FRTL-5 cells. These data indicated that the loss of thyroid-specific expression of Tg and TPO genes in FRTL-5/TA cells was not related to changes in TTF-1 gene expression but rather to reduced Pax-8 gene expression. It was concluded that a disruption of the co-ordinated expression of TTF-1 and Pax-8 is implicated in the loss of thyroid phenotype of FRTL-5/TA cells in terms of reduced Tg and TPO expression.
Journal of Endocrinology (1996) 150, 377–382
