scholarly journals Activation of the Thyroid-Stimulating Hormone β-Subunit Gene by LIM Homeodomain Transcription Factor Lhx2

Endocrinology ◽  
2007 ◽  
Vol 148 (7) ◽  
pp. 3468-3476 ◽  
Author(s):  
Kee K. Kim ◽  
Seok B. Song ◽  
Kwang I. Kang ◽  
Myungchull Rhee ◽  
Kyoon Eon Kim
Keyword(s):  
Transcription Factor ◽  
Reporter Gene ◽  
Thyroid Stimulating Hormone ◽  
Β Subunit ◽  
Subunit Gene ◽  
Mobility Shift ◽  
Glycoprotein Hormone ◽  
Α Subunit ◽  
Homeodomain Transcription Factor ◽  
Lim Homeodomain

Although there is evidence that the LIM homeodomain transcription factor, Lhx2, can stimulate transcription of the glycoprotein hormone α-subunit gene, the role of Lhx2 in regulating TSH β-subunit has not been established. In the present studies, the ability of Lhx2 to regulate transcription of the TSH β-subunit gene was examined. In the thyrotrope-derived TαT1 cell line, Lhx2 expression was found to be induced by treatment with either TRH or cAMP, consistent with the possibility that Lhx2 may play a role in mediating the ability of this signaling pathway to stimulate TSH gene expression. Transient, forced overexpression of Lhx2 stimulated activity of a TSH β-subunit reporter gene. Deletion studies provided evidence that the −177 to −79 region of the TSH β-subunit promoter was necessary for stimulation of reporter gene activity by Lhx2. A gel mobility shift assay provided the evidence that Lhx2 can bind to this region of DNA. DNase I footprinting studies demonstrated that two distinct regions of the TSHβ promoter, −118 to −108 and −86 to −68, are protected by Lhx2 from nuclease digestion. These regions contain repeats of the sequence, 5′-(G/T)CAAT(T/A)-3′. Mutation of this sequence, especially in the −86 to −68 region, substantially decreased Lhx2 responsiveness of the TSH β-subunit reporter gene. In addition, a DNA fragment containing the −177 to −79 region of the TSHβ promoter was found to confer Lhx2 responsiveness to a minimal promoter. These results provide multiple lines of evidence consistent with a role for Lhx2 in modulating expression of the TSH β-subunit gene.

scholarly journals Pituitary transcription factor Prop-1 stimulates porcine pituitary glycoprotein hormone α subunit gene expression

2006 ◽  
Vol 37 (2) ◽  
pp. 341-352 ◽  
Author(s):  
Takanobu Sato ◽  
Kousuke Kitahara ◽  
Takao Susa ◽  
Takako Kato ◽  
Yukio Kato
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Binding Sites ◽  
Gh3 Cells ◽  
Pituitary Hormone ◽  
Transcriptional Level ◽  
Β Subunit ◽  
Glycoprotein Hormone ◽  
Α Subunit

Recently, we have reported that a Prophet of Pit-1 homeodomain factor, Prop-1, is a novel transcription factor for the porcine follicle-stimulating hormone β subunit (FSHβ) gene. This study subsequently aimed to examine the role of Prop-1 in the gene expression of two other porcine gonadotropin subunits, pituitary glycoprotein hormone α subunit (αGSU), and luteinizing hormone β subunit (LHβ). A series of deletion mutants of the porcine αGSU (up to −1059 bp) and LHβ (up to −1277 bp) promoters were constructed in the reporter vector, fused with the secreted alkaline phosphatase gene (pSEAP2-Basic). Transient transfection studies using GH3 cells were carried out to estimate the activation of the porcine αGSU and LHβ promoters by Prop-1, which was found to activate the αGSU promoter of −1059/+12 bp up to 11.7-fold but not the LHβ promoter. Electrophoretic mobility shift assay and DNase I footprinting analysis revealed that Prop-1 binds to six positions, −1038/−1026, −942/−928, −495/−479, −338/−326, −153/−146, and −131/−124 bp, that comprise the A/T cluster. Oligonucleotides of six Prop-1 binding sites were directly connected to the minimum promoter of αGSU, fused in the pSEAP2-Basic vector, followed by transfecting GH3 cells to determine the cis-acting activity. Finally, we concluded that at least five Prop-1 binding sites are the cis-acting elements for αGSU gene expression. The present results revealed a notable feature of the proximal region, where three Prop-1-binding sites are close to and/or overlap the pituitary glycoprotein hormone basal element, GATA-binding element, and junctional regulatory element. To our knowledge, this is the first demonstration of the role of Prop-1 in the regulation of αGSU gene expression. These results, taken together with our previous finding that Prop-1 is a transcription factor for FSHβ gene, confirm that Prop-1 modulates the synthesis of FSH at the transcriptional level. On the other hand, the defects of Prop-1 are known to cause dwarfism and combined pituitary hormone deficiency accompanying hypogonadism. Accordingly, the present observations provide a novel view to understand the hypogonadism caused by Prop-1 defects at the molecular level through the regulatory mechanism of αGSU and FSHβ gene expressions.

FSH in therapy: physiological basis, new preparations and clinical use

1995 ◽  
Vol 4 (3) ◽  
pp. 163-177 ◽  
Author(s):  
Manuela Simoni ◽  
Eberhard Nieschlag
Keyword(s):  
Follicle Stimulating Hormone ◽  
Thyroid Stimulating Hormone ◽  
Clinical Use ◽  
Β Subunit ◽  
Glycoprotein Hormone ◽  
Physiological Basis ◽  
Α Subunit ◽  
And Function ◽  
Polypeptide Chains ◽  
Stimulating Hormone

Follicle stimulating hormone (FSH) is a glycoprotein hormone secreted by the pituitary gland that, together with luteinizing hormone (LH), controls development, maturation and function of the gonad. Like the related hormones, LH, thyroid stimulating hormone (TSH) and human chorionic gonadotropin (hCG), FSH consists of two polypeptide chains, α and β, bearing carbohydrate moietiesN-linked to asparagine (Asn) residues. The α subunit is common to all members of the glycoprotein hormone family, whereas the β subunit, although structurally very similar, differs in each hormone and confers specificity of action.

hCG production and activity during pregnancy

2001 ◽  
Vol 12 (3) ◽  
pp. 191-208 ◽  
Author(s):  
H S Randeva ◽  
A Jackson ◽  
E Karteris ◽  
E W Hillhouse
Keyword(s):  
Luteinizing Hormone ◽  
Chorionic Gonadotropin ◽  
Essential Role ◽  
Follicle Stimulating Hormone ◽  
Thyroid Stimulating Hormone ◽  
Β Subunit ◽  
Glycoprotein Hormone ◽  
Α Subunit ◽  
Hormone Specificity ◽  
Stimulating Hormone

Human chorionic gonadotropin (hCG) has an essential role in early pregnancy. It is a member of the glycoprotein hormone family also comprising the pituitary derived follicle stimulating hormone (FSH), luteinizing hormone (LH) and thyroid stimulating hormone (TSH). Each hormone consists of a non-covalently bound α and β subunit. Within a species the α subunit is identical and hormone specificity is determined by the unique β subunit.

scholarly journals Regulation of the Follicle-Stimulating Hormone β Gene by the LHX3 LIM-Homeodomain Transcription Factor

Endocrinology ◽  
2004 ◽  
Vol 145 (11) ◽  
pp. 4866-4879 ◽  
Author(s):  
Brooke E. West ◽  
Gretchen E. Parker ◽  
Jesse J. Savage ◽  
Parinda Kiratipranon ◽  
Katherine S. Toomey ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Binding Sites ◽  
Quantitative Methods ◽  
Proximal Region ◽  
Dominant Negative ◽  
Β Subunit ◽  
Homeodomain Transcription Factor ◽  
Functional Conservation ◽  
Drosophila Protein ◽  
Lim Homeodomain

Abstract FSH is a critical hormone regulator of gonadal function that is secreted from the pituitary gonadotrope cell. Human patients and animal models with mutations in the LHX3 LIM-homeodomain transcription factor gene exhibit complex endocrine diseases, including reproductive disorders with loss of FSH. We demonstrate that in both heterologous and pituitary gonadotrope cells, specific LHX3 isoforms activate the FSH β-subunit promoter, but not the proximal LHβ promoter. The related LHX4 mammalian transcription factor can also induce FSHβ promoter transcription, but the homologous Drosophila protein LIM3 cannot. The actions of LHX3 are specifically blocked by a dominant negative LHX3 protein containing a Krüppel-associated box domain. Six LHX3-binding sites were characterized within the FSHβ promoter, including three within a proximal region that also mediates gene regulation by other transcription factors and activin. Mutations of the proximal binding sites demonstrate their importance for LHX3 induction of the FSHβ promoter and basal promoter activity in gonadotrope cells. Using quantitative methods, we show that the responses of the FSHβ promoter to activin do not require induction of the LHX3 gene. By comparative genomics using the human FSHβ promoter, we demonstrate structural and functional conservation of promoter induction by LHX3. We conclude that the LHX3 LIM homeodomain transcription factor is involved in activation of the FSH β-subunit gene in the pituitary gonadotrope cell.

FSH in therapy: physiological basis, new preparations and clinical use

1995 ◽  
Vol 4 (3) ◽  
pp. 163-177 ◽  
Author(s):  
Manuela Simoni ◽  
Eberhard Nieschlag
Keyword(s):  
Follicle Stimulating Hormone ◽  
Thyroid Stimulating Hormone ◽  
Clinical Use ◽  
Β Subunit ◽  
Glycoprotein Hormone ◽  
Physiological Basis ◽  
Α Subunit ◽  
And Function ◽  
Polypeptide Chains ◽  
Stimulating Hormone

Follicle stimulating hormone (FSH) is a glycoprotein hormone secreted by the pituitary gland that, together with luteinizing hormone (LH), controls development, maturation and function of the gonad. Like the related hormones, LH, thyroid stimulating hormone (TSH) and human chorionic gonadotropin (hCG), FSH consists of two polypeptide chains, α and β, bearing carbohydrate moietiesN-linked to asparagine (Asn) residues. The α subunit is common to all members of the glycoprotein hormone family, whereas the β subunit, although structurally very similar, differs in each hormone and confers specificity of action.

Expression of mRNA coding for pituitary hormones and pituitary-specific transcription factor in the pituitary gland of the rdw rat with hereditary dwarfism

1993 ◽  
Vol 138 (2) ◽  
pp. 307-313 ◽  
Author(s):  
K. Shibayama ◽  
Y. Ohyama ◽  
M. Ono ◽  
S. Furudate
Keyword(s):  
Transcription Factor ◽  
Pituitary Gland ◽  
Mouse Strains ◽  
Northern Hybridization ◽  
Pituitary Hormone ◽  
Β Subunit ◽  
Glycoprotein Hormone ◽  
Α Subunit ◽  
Specific Transcription Factor ◽  
Significant Difference

ABSTRACT The rdw rat (gene symbol: rdw) with hereditary dwarfism has been shown immunohistochemically to have subnormal numbers not only of GH- but also of prolactin- and thyrotrophin-positive cells. To characterize the dwarfism of this strain, the expression of pituitary hormone mRNAs was examined by Northern hybridization. The pituitary gland in the rdw rat expressed 30–100 times less GH and prolactin mRNAs than normal controls, whereas mRNAs for pro-opiomelanocortin and the α subunit of rat glycoprotein hormone revealed a significant increase. There was a non-significant difference in rat LH-β subunit and FSH-β subunit between normal and rdw rats. The suppressed expression of a pituitary-specific transcription factor, Pit-1, is considered to cause hereditary dwarfism in mouse strains Snell and Jackson, whose phenotypes resemble those of the rdw rat. In this study, however, no difference in mRNA expression for Pit-1 was found between rdw rats and controls. This work indicates that the rdw rat may not have the same genotype as the phenotypically similar dwarf mice, Snell, Jackson and Ames. Journal of Endocrinology (1993) 138, 307–313

scholarly journals Activation of the glycoprotein hormone alpha-subunit promoter by a LIM-homeodomain transcription factor.

1994 ◽  
Vol 14 (5) ◽  
pp. 2985-2993 ◽  
Author(s):  
M S Roberson ◽  
W E Schoderbek ◽  
G Tremml ◽  
R A Maurer
Keyword(s):  
Transcription Factor ◽  
Binding Activity ◽  
Alpha Subunit ◽  
Homeodomain Protein ◽  
Pituitary Cells ◽  
Glycoprotein Hormone ◽  
Homeodomain Transcription Factor ◽  
Imperfect Palindrome ◽  
Recombinant Lh ◽  
Lim Homeodomain

Recently, a pituitary-specific enhancer was identified within the 5' flanking region of the mouse glycoprotein hormone alpha-subunit gene. This enhancer is active in pituitary cells of the gonadotrope and thyrotrope lineages and has been designated the pituitary glycoprotein hormone basal element (PGBE). In the present studies, we sought to isolate and characterize proteins which interact with the PGBE. Mutagenesis experiments identified a 14-bp imperfect palindrome that is required for binding of a factor which is present in cells of gonadotrope and thyrotrope lineages but not in other cells. Screening of a mouse cDNA library with a DNA probe containing the imperfect palindrome resulted in the isolation of a LIM-homeodomain transcription factor. The cDNA predicts a mouse protein which is 94% identical to the recently described rat LIM-homeodomain protein LH-2. LH-2 contains two zinc fingers (LIM domain) and a consensus homeodomain. Hybridization analysis revealed relatively high expression of LH-2 mRNA in the central nervous system and in pituitary cells of the gonadotrope and thyrotrope lineages. Lower or nondetectable levels of LH-2 mRNA were found in other pituitary cells and tissues, including placental cells. Recombinant LH-2 homeodomain was found to selectively bind to the previously identified imperfect palindrome in the PGBE. Point mutations in the PGBE resulted in parallel losses in the binding of a nuclear factor from a cell line of the gonadotrope lineage and recombinant LH-2-binding activity. Use of an antibody to LH-2 provided evidence that endogenous PGBE-binding activity from cells of the gonadotrope lineage involves a protein which is immunologically related to LH-2. Expression of LH-2 in two heterologous cell types resulted in activation of a reporter gene containing the mouse alpha promoter. These data suggest that the LIM-homeodomain factor LH-2 plays a role in stimulating tissue-specific expression of the mouse glycoprotein hormone alpha subunit. The finding that a LIM-homeodomain protein can stimulate expression of one of the earliest markers of pituitary differentiation raises the possibility that this factor plays a role in cell lineage determination in the pituitary.

Activation of the glycoprotein hormone alpha-subunit promoter by a LIM-homeodomain transcription factor

1994 ◽  
Vol 14 (5) ◽  
pp. 2985-2993
Author(s):  
M S Roberson ◽  
W E Schoderbek ◽  
G Tremml ◽  
R A Maurer
Keyword(s):  
Transcription Factor ◽  
Binding Activity ◽  
Alpha Subunit ◽  
Homeodomain Protein ◽  
Pituitary Cells ◽  
Glycoprotein Hormone ◽  
Homeodomain Transcription Factor ◽  
Imperfect Palindrome ◽  
Recombinant Lh ◽  
Lim Homeodomain

Recently, a pituitary-specific enhancer was identified within the 5' flanking region of the mouse glycoprotein hormone alpha-subunit gene. This enhancer is active in pituitary cells of the gonadotrope and thyrotrope lineages and has been designated the pituitary glycoprotein hormone basal element (PGBE). In the present studies, we sought to isolate and characterize proteins which interact with the PGBE. Mutagenesis experiments identified a 14-bp imperfect palindrome that is required for binding of a factor which is present in cells of gonadotrope and thyrotrope lineages but not in other cells. Screening of a mouse cDNA library with a DNA probe containing the imperfect palindrome resulted in the isolation of a LIM-homeodomain transcription factor. The cDNA predicts a mouse protein which is 94% identical to the recently described rat LIM-homeodomain protein LH-2. LH-2 contains two zinc fingers (LIM domain) and a consensus homeodomain. Hybridization analysis revealed relatively high expression of LH-2 mRNA in the central nervous system and in pituitary cells of the gonadotrope and thyrotrope lineages. Lower or nondetectable levels of LH-2 mRNA were found in other pituitary cells and tissues, including placental cells. Recombinant LH-2 homeodomain was found to selectively bind to the previously identified imperfect palindrome in the PGBE. Point mutations in the PGBE resulted in parallel losses in the binding of a nuclear factor from a cell line of the gonadotrope lineage and recombinant LH-2-binding activity. Use of an antibody to LH-2 provided evidence that endogenous PGBE-binding activity from cells of the gonadotrope lineage involves a protein which is immunologically related to LH-2. Expression of LH-2 in two heterologous cell types resulted in activation of a reporter gene containing the mouse alpha promoter. These data suggest that the LIM-homeodomain factor LH-2 plays a role in stimulating tissue-specific expression of the mouse glycoprotein hormone alpha subunit. The finding that a LIM-homeodomain protein can stimulate expression of one of the earliest markers of pituitary differentiation raises the possibility that this factor plays a role in cell lineage determination in the pituitary.

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