Activation of Cell-Specific Expression of Rat Growth Hormone and Prolactin Genes by a Common Transcription Factor

Nelson, Christine; Albert, Vivian R.; Elsholtz, Harry P.; Lu, Leslie I. W.; Rosenfeld, Michael G.

doi:10.1126/science.2831625

Cited by 519 publications

(310 citation statements)

References 33 publications

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“…It is mainly expressed in the pituitary and its expression is necessary for the normal differentiation, development and survival of three adenohypophysis cell types, thyrotrophs, somatotrophs and lactotrophs (Li et al, 1990;Simmons et al, 1990). It is also important for the proper expression of growth hormone (GH ), prolactin (PRL) (Lefevre et al, 1987;Nelson et al, 1988), thyroid-stimulating hormone (TSH ) (Li et al, 1990) and POU1F1 gene itself (Chen et al, 1990;McCormick et al, 1990).…”

Section: Introductionmentioning

confidence: 99%

Identification and characterization of four splicing variants of ovine POU1F1 gene

Bastos

Ávila

Cravador

et al. 2006

Gene

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Expression of POU1F1 gene, a member of the POU homeodomain family of transcription factors, is necessary for normal differentiation, development and survival of three anterior pituitary cell types (thyrotrophs, somatotrophs and lactotrophs) and for the proper expression of growth hormone (GH ), prolactin (PRL), thyroid-stimulating hormone (TSH ) genes and POU1F1 gene itself. Alternative splicing forms of this gene have been reported in different species, with few functional studies. Apart from the POU1F1-Wild-type with the expected length, in this work we isolated three additional splicing variants: POU1F1-β, with a 78 bp insert in the trans-activation domain; POU1F1-γ that lacks exon 3 and POU1F1-δ that lacks exons 3, 4 and 5. Four different protein isoforms were also detected by Western blot in the sheep pituitary tissue. Functional assays were performed to study the trans-activation of GH and PRL promoters by the splicing variants. Regarding the PRL promoter, the β variant presented only 12% of the Wild-type trans-activation capacity. Variants γ and δ showed no capacity to trans-activate PRL promoter. Both γ and δ variants acted as repressors of Wt, reducing significantly the trans-activation made by Wt alone ( p < 0.05). Concerning the GH promoter, the β variant presented a trans-activation capacity 10% higher than Wt. Wt and β variants strongly interact in the activation of GH promoter doubling the trans-activation potential of Wt. Variants γ and δ showed no capacity to trans-activate the GH promoter and both acted as repressors, reducing significantly ( p < 0.001) the trans-activation performed by Wt. This work presents, for the first time, the characterization of four splicing forms of Ovis aries POU1F1 gene.

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Section: Introductionmentioning

confidence: 99%

Identification and characterization of four splicing variants of ovine POU1F1 gene

Bastos

Ávila

Cravador

et al. 2006

Gene

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“…Several homeodomain-containing proteins other than Gtx, including Pdx1 in the pancreas (Ohlsson et al, 1993;Ahlgren et al, 1996), TTF-1 in lung and thyroid (Lazzaro et al, 1991;Bruno et al, 1995), and Pit-1 in the pituitary (Nelson et al, 1988;Mangalam et al, 1989;Simmons et al, 1990), have been shown both to be expressed in terminally differentiated cells and to bind to the promoters of tissue specific genes, implicating them in their regulation. Both Pit-1 and Pdx1, however, are also expressed early in development of the pituitary (Li et al, 1990) and pancreas (Jonsson et al, 1994;Ahlgren et al, 1996), respectively, and inactivation of either their expression or their f unction has demonstrated that they also are necessary for normal organogenesis.…”

Section: Homeodomain Proteins Gtx and Developmentmentioning

confidence: 99%

Evidence That the Homeodomain Protein Gtx Is Involved in the Regulation of Oligodendrocyte Myelination

et al. 1997

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We have investigated the patterns of postnatal brain expression and DNA binding of Gtx, a homeodomain transcription factor. Gtx mRNA accumulates in parallel with the RNAs encoding the major structural proteins of myelin, myelin basic protein (MBP), and proteolipid protein (PLP) during postnatal brain development; Gtx mRNA decreases in parallel with MBP and PLP mRNAs in the brains of myelin-deficient rats, which have a point mutation in the PLP gene. Gtx mRNA is expressed in differentiated, postmitotic oligodendrocytes but is not found in oligodendrocyte precursors or astrocytes. These data thus demonstrate that Gtx is expressed uniquely in differentiated oligodendrocytes in postnatal rodent brain and that its expression is regulated in parallel with the major myelin protein mRNAs, encoding MBP and PLP, under a variety of physiologically relevant circumstances.Using a Gtx fusion protein produced in bacteria, we have confirmed that Gtx is a sequence-specific DNA-binding protein, which binds DNA sequences containing a core AT-rich homeodomain binding site. Immunoprecipitation of labeled DNA fragments encoding either the MBP or PLP promoter regions with this fusion protein has identified several Gtx-binding fragments, and we have confirmed these data using an electrophoretic mobility shift assay. In this way we have identified four Gtx binding sites within the first 750 bp of the MBP promoter and four Gtx binding sites within the first 1.3 kb of the PLP promoter. In addition, inspection of the PLP promoter sequence demonstrates the presence of six additional Gtx binding sites. These data, taken together, strongly suggest that Gtx is important for the function of differentiated oligodendrocytes and may be involved in the regulation of myelin-specific gene expression.

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“…7). In order to determine whether BrdU itself affected PRL producing cell induction, we performed the following three experiments: cells were incubated with [1] insulin and EGF for 24 h, [2] BrdU for 24 h and [3] normal medium for 24 h and then subjected to double labeling immunocytochemical staining for BrdU and PRL, as described above. These preliminary experiments showed that BrdU itself did not affect PRL-producing cell differentiation (data not shown).…”

Section: Immunocytochemistrymentioning

confidence: 99%

“…In order to analyze the relationship between cell proliferation and differentiation, MtT/S cells were cultivated under three different growth conditions: they were cultivated [1] in growth medium and harvested 0,12 and 24 h after adding insulin and EGF (control group); [2] in 1/4 serum medium for 7 days, the medium was replaced with growth medium, and differentiation into PRL-producing cells was induced by incubation with insulin and EGF for 0,12 and 24 h (growth group) and, [3] in 1/4 serum medium for 7 days and then stimulated with insulin and EGF for 0,12 and 24 h (starvation group). After cultivation, the cells were dispersed with 0.025% trypsin, washed twice with calciumfree phosphate-buffered saline (PBS) and fixed with 70% ethanol at 4 °C.…”

Section: Flow-cytometry and Cell Sortingmentioning

confidence: 99%

Prolactin-Producing Cells Differentiate from G0/G1-Arrested Somatotrophs In Vitro: An Analysis of Cell Cycle Phases and Mammotroph Differentiation.

et al. 1998

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Abstract.In order to analyze the relationship between cell proliferation and mammotroph differentiation,we studied a somatotrophic cell line, MtT/S. MtT/S cell is known to differentiate into PRL-producing cells in response to stimulation with insulin or insulin-like growth factor-1 (IGF-1). Double immunostaining for bromodeoxyuridine (BrdU), which labels proliferating cells, and for GH or PRL showed that most BrdU-labeled cells were GH-immunopositive, whereas considerably few PRLpositive cells were labeled with BrdU. This was confirmed by immunostaining of proliferating cells with antibody to proliferating cell nuclear antigen (PCNA). Furthermore, flow-cytometry analysis indicated that most of the PRL-producing cells were in the GO/G1 phase of the cell cycle. In order to determine whether cell cycle changes are required for transdifferantiation of PRL-producing cells, MtT/S cells were cultivated in serum restricted medium for 7 days to reduce their mitotic activity and then treated with insulin and epidermal growth factor (EGF). Under these conditions, the cell cycle of MtT/S cells was significantly delayed, but the percentage of PRL-producing cells induced was almost identical to that under control conditions, showing that mitosis is not required for PRL-producing cell differentiation. We also labeled MtT/S cells with BrdU for 24 h during PRL-producing cell induction by insulin and EGF, and as a result BrdU-labeled proliferative cells were specifically absent from PRL-producing cell populations. These data, taken as whole, suggest that PRL cells differentiated from GO/G1 arrested somatotrophs and the PRL cells which appeared had their cell proliferation activity significantly declined. In conclusion, this is the first report showing the relationship cell between proliferation and differentiation of PRL cells.

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Activation of Cell-Specific Expression of Rat Growth Hormone and Prolactin Genes by a Common Transcription Factor

Cited by 519 publications

References 33 publications

Identification and characterization of four splicing variants of ovine POU1F1 gene

Identification and characterization of four splicing variants of ovine POU1F1 gene

Evidence That the Homeodomain Protein Gtx Is Involved in the Regulation of Oligodendrocyte Myelination

Prolactin-Producing Cells Differentiate from G0/G1-Arrested Somatotrophs In Vitro: An Analysis of Cell Cycle Phases and Mammotroph Differentiation.

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