Dissection of functional domains of the pituitary-specific transcription factor GHF-1

Theill, Lars E.; Castrillo, José Luis; Wu, David J.; Karin, Michael

doi:10.1038/342945a0

Cited by 248 publications

(158 citation statements)

References 32 publications

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“…X-chromosome from several metaphases (bottom row) to MLL in acute leukemias with a t(X;11)(q13;q23). In accordance with the other MLL partner proteins AF4, AF9, AF10 and ENL, the AFX protein has a high content of serine and proline, a feature that is commonly found in transcriptional activators (Theill et al, 1989). Using the sequence alignment methodology, we not only con®rm that AFX is a member of the forkhead gene family (Parry et al, 1994), but also show that it has a signi®cant homology to the FKHR gene outside the forkhead domain at the aminoterminal part.…”

Section: Discussionsupporting

confidence: 67%

Cloning and characterization of AFX, the gene that fuses to MLL in acute leukemias with a t(X;11)(q13;q23)

et al. 1997

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We report the cloning and characterization of the entire AFX gene which fuses to MLL in acute leukemias with a t(X;11)(q13;q23). AFX consists of two exons and encodes for a protein of 501 amino acids. We found that normal B-and T-cells contain similar levels of AFX mRNA and that both the MLL/AFX as well as the AFX/MLL fusion transcripts are present in the cell line and the ANLL sample with a t(X;11)(q13;q23). The single intron of the AFX gene consists of 3706 nucleotides. It contains ®ve simple sequence repeats with lengths of at least 12 bps, a chi-like octamer sequence (GCA/TGGA/TGG) and several immunoglobulin heptamer-like sequences (GATAGTG) that are distributed throughout the entire AFX intron sequence. In the KARPAS 45 cell line the breakpoints occur at nucleotides 2913/2914 of the AFX intron and at nucleotides 4900/4901 of the breakpoint cluster region of the MLL gene. The AFX protein belongs to the forkhead protein family. It is highly homologous to the human FKHR protein, the gene of which is disrupted by the t(2;13)(q35;q14), a chromosome rearrangement characteristic of alveolar rhabdomyosarcomas. It is noteworthy that the t(X;11)(q13;q23) in the KARPAS 45 cell line and in one acute nonlymphoblastic leukemia (ANLL) disrupts the forkhead domain of the AFX protein exactly at the same amino acids as does the t(2;13)(q35;q14) in case of the FKHR protein. In addition, the 5'-part of the AFX protein contains a conserved hexapeptide motif (QIYEWM) that is homologous to the functionally important conserved hexapeptide QIYPWM upstream of the homeobox domain in Hox proteins. This motif mediates the co-operative DNA binding of Pbx family members and Hox proteins and, therefore, plays an important role in physiologic and oncogenic processes. In acute leukemias with a t(X;11)(q13;q23), this hexapeptide motif is separated from the remaining forkhead domain within the AFX protein. The predicted amino acid sequence of AFX di ers signi®cantly from the partial AFX protein sequence published previously (Genes, Chromosomes and Cancer, 1994, 11, 79 ± 84). This discrepancy can be explained by the occurrence of two sequencing errors in the earlier work at nucleotide number 783 and 844 (loss of a cytosine residue or guanosine residue, respectively) that lead to two reading frame shifts.

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Section: Discussionsupporting

confidence: 67%

Cloning and characterization of AFX, the gene that fuses to MLL in acute leukemias with a t(X;11)(q13;q23)

et al. 1997

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“…The four O. aries RSV-POU1F1 plasmids were constructed by replacing the HindIII-NotI rat GHF-1 coding fragment of RSV rat GHF-1 (Theill et al, 1989) by a similar fragment containing the coding sequence of ovine POU1F1-Wt, -β, -γ and -δ transcripts obtained by HindIII-NotI digestion of previously sequenced pKS cDNA vectors.…”

Section: Expression Vectors and Reporter Gene Constructsmentioning

confidence: 99%

“…The POU1F1 gene, as described by Theill et al (1989Theill et al ( , 1992, contains six exons and five introns and encodes a protein with 33 kDa. This transcription factor contains two important regions for the transcriptional regulation of target promoters: a N-terminal trans-activation domain (TAD) spanning amino acids 1 to 80 and a C-terminal DNA-binding and dimerization domain that consists of a POU-specific domain (POU S from aa 128 to 198) and a POU homeodomain (POU HD from aa 214 to 273).…”

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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“…Its role in somatotrope cell growth and its ability to transactivate the growth hormone and prolactin gene promoters are well documented (12,15,16). Based on binding studies with the growth hormone, prolactin, and Pit-1 promoters, a consensus DNA recognition element ((T/A)(T/A)TATNCAT) has been derived (12,17).…”

mentioning

confidence: 99%

Pit-1 and GATA-2 Interact and Functionally Cooperate to Activate the Thyrotropin β-Subunit Promoter

Gordon

Lewis

Haugen

et al. 1997

Journal of Biological Chemistry

128

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The molecular determinants governing cell-specific expression of the thyrotropin (TSH) ␤-subunit gene in pituitary thyrotropes are not well understood. The P1 region of the mouse TSH␤ promoter (؊133 to ؊88) region interacts with Pit-1 and an additional 50-kDa factor at an adjacent site that resembles a consensus GATA binding site. Northern and Western blot assays demonstrated the presence of GATA-2 transcripts and protein in TtT-97 thyrotropic tumors. In electrophoretic mobility shift assays, a comigrating complex was observed with both TtT-97 nuclear extracts and GATA-2 expressed in COS cells. The complex demonstrated binding specificity to the P1 region DNA probe and could be disrupted by a GATA-2 antibody. When both Pit-1 and GATA-2 were combined, a slower migrating complex, indicative of a ternary protein-DNA interaction was observed. Cotransfection of both Pit-1 and GATA-2 into CV-1 cells synergistically stimulated mouse TSH␤ promoter activity 8.5-fold, while each factor alone had a minimal effect. Mutations that abrogated this functional stimulatory effect mapped to the P1 region. Finally, we show that GATA-2 directly interacts with Pit-1 in solution. In summary, these data demonstrate functional synergy and physical interaction between homeobox and zinc finger factors and provide insights into the transcriptional mechanisms of thyrotrope-specific gene expression.Cell-specific expression of eukaryotic genes involves the functional interaction of sets of transcription factors that interact with essential cis-acting promoter regions to initiate RNA transcription. The repertoires of transcription factors that are involved in the expression of genes in highly differentiated cells often consist of those ubiquitously expressed in many cell types in cooperation with others whose expression are cell type-restricted (1, 2). Expression of the thyrotropin (TSH) 1

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Dissection of functional domains of the pituitary-specific transcription factor GHF-1

Cited by 248 publications

References 32 publications

Cloning and characterization of AFX, the gene that fuses to MLL in acute leukemias with a t(X;11)(q13;q23)

Cloning and characterization of AFX, the gene that fuses to MLL in acute leukemias with a t(X;11)(q13;q23)

Identification and characterization of four splicing variants of ovine POU1F1 gene

Pit-1 and GATA-2 Interact and Functionally Cooperate to Activate the Thyrotropin β-Subunit Promoter

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