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At least 19 recordsLinked to original sources

PubMed1993

[The pituitary glycoprotein hormones, alpha subunit].

Pituitary glycoprotein hormones FSH (follicle-stimulating hormone), LH (luteinizing hormone) and thyrotropic hormone, TSH (thyroid-stimulating hormone) are formed by two subunits: alpha which is essentially the same for all three hormones, and beta which is responsible for their biochemical specificity. The alpha subunit is from the quantitative aspect a very important secretion of the pituitary. Part of the alpha subunit produced in the pituitary is not used for the synthesis of hypophyseal glycoprotein hormones and is secreted in a pulsed way synchronously with the pulsed LH secretion into the peripheral blood stream. Levels of the free alpha subunit in the peripheral blood depend on a number of factors in particular age, sex and in women on the stage of the menstrual cycle. The physiological roles of the free alpha subunit are only partially known. It is assumed that the most important part is the participation in the modulation of the effect of hypophyseal glycoprotein hormones at the level of their peripheral tissues. During the last few years it was revealed, surprisingly, that the level of the free alpha subunit in plasma may be used as a tumour marker as this parameter rises during some pathological conditions, in particular in adenomas of the pituitary.

Adolescent↗

PubMed1996

Insect cells infected with a recombinant baculovirus express both O- and N-glycosylated forms of the rat glycoprotein hormone alpha-subunit.

Glycoprotein hormones LH, FSH, TSH and chorionic gonadotrophin are heterodimers composed of two non-covalently associated subunits, a common alpha- and a specific beta-subunit. A recombinant baculovirus containing a cDNA encoding the alpha-subunit of rat glycoprotein hormones was constructed. Viral-infected cells expressed, 48 h post infection, 7-10 mg immunoreactive alpha-glycopolypeptide/6 x 10(8) cells, of which 65-6% was able to associate with native LH beta and formed a biologically active heterodimeric hormone that bound to testicular receptors. The treatment with specific glycanases showed that the recombinant alpha-subunit was produced as two differently glycosylated forms; an M(r) 23 000 form which contained exclusively N-linked carbohydrate units and another of M(r) 25 000 which appeared to contain additional 0-linked carbohydrate. Data demonstrated that the alpha-subunit was expressed by insect cells in a manner similar to that by mammalian pituitary gonadotropes producing both the N- and O-glycosylated forms although only the N-glycosylated alpha-subunit is known to be capable of associating with the beta-subunit.

Animals↗

PubMed1989

[Free alpha-subunit glycoprotein hormones: physiological and pathological data].

The glycoprotein hormone alpha-subunit is secreted as a free molecule as well as a molecule combined to a glycoprotein hormone beta-subunit. In human subjects, plasma levels of the free alpha-subunit were measured by means of a specific radioimmunoassay. Plasma concentrations were high during the neonatal period, then decreased to a nadir at the age of 6 years. A significant pubertal increase occurred in both sexes, more pronounced in girls. In female subjects mean levels (+/- SEM) were 0.21 +/- 0.05 before puberty and 0.51 +/- 0.03 ng 1 degrees IRP-hCG alpha/ml in follicular phase. During menstrual cycle, a typical preovulatory surge was seen simultaneous with the LH surge. During aging, plasma levels increased slowly in males, abruptly in menopausal females. The pituitary reserve as assessed by LH-RH stimulation test (100 micrograms i.v./m2) exhibited a significant pubertal maturation in boys and girls. Chronic administration of LH-RH agonist induced a marked increase of alpha-subunit levels, whereas LH levels were deeply suppressed. LH-RH injections in children treated for precocious puberty with a LH-RH agonist induced a significant release of alpha-subunit despite an almost complete abolition of LH release. In conclusion, from a quantitative point of view, the glyco-protein hormone alpha-subunit is a major secretory product of the pituitary. It seems that there is a specific regulation of its secretion, resembling but not identical to LH secretion regulation. Whether or not it plays a biological role remains uncertain.

Child↗

PubMed2005

Transcriptional activity of the 5' upstream region of the porcine glycoprotein hormone alpha subunit gene.

Gene expression of the porcine glycoprotein hormone alpha subunit (p-alphaGSU) was examined in LbetaT2 cells, which were established from the anterior pituitary lobe of the immortalized transgenic mouse and produce alphaGSU, and in CHO cells cloned from Chinese hamster ovaries. Expression of the reporter gene fused with p-alphaGSU gene upstream in LbetaT2 cells showed that the distal regions -540/-240 and -798/-541 are important for the activation of gene expression. In contrast, the transcriptional activity of the distal region of p-alphaGSU gene was repressed in CHO cells. The region -540/-240 contains an adequate enhancer, called pituitary glycoprotein hormone basal element, whereas the region -798/-541 has no distinguished element. Transfection of the expression vector containing cDNA of a pan-pituitary activator, Ptx1, whose putative binding sites are present scatted in the distal region of the p-alphaGSU gene, revealed unexpectedly that this factor significantly suppressed the expression of p-alphaGSU gene in LbetaT2 cells, indicating that Ptx1 is unrelated to the upregulation in the region -798/-541. Thus, this study demonstrated for the first time that the distal region -798/-541of the p-alphaGSU gene is indispensable for prominent expression of this gene in which an as yet unidentified factor may participate.

Animals↗

PubMed1979

Serum glycoprotein hormone alpha subunit levels in patients with cancer.

The serum glycoprotein hormone alpha subunit concentration was measured in 957 nonpregnant patients with benign disorders and 683 patients with unselected malignancies. Postmenopausal women had significantly higher alpha levels than premenopausal women or men. When the patients were subdivided according to age, sex or disease sites, significant population differences were found for women less than 50 years of age and patients with cancers of presumed neural crest origin. However, individual serum alpha levels in patients with benign disorders or malignancies demonstrated considerable overlap. No population differences in serum alpha concentrations were demonstrated between patients grouped according to stage of disease, suggesting that serum alpha were not directly related to tumor burden. Similarly, there was no statistical association between clinical improvement or deterioration and change in the serum alpha subunit concentration. These results indicate that measurement of the glycoprotein hormone alpha subunit concentration in the serum is not useful for screening patients for cancer or for monitoring the clinical course of patients with the vast majority of cancers.

Age Factors↗

PubMed1995

Upstream stimulatory factor, a basic-helix-loop-helix-zipper protein, regulates the activity of the alpha-glycoprotein hormone subunit gene in pituitary cells.

In an effort to determine whether basic-helix-loop-helix (bHLH) proteins are important in pituitary-specific expression of the alpha-glycoprotein hormone subunit gene, we examined the effect of the dominant negative HLH protein, Id, on the activity of the alpha-subunit gene promoter in pituitary cells. Id over-expression reduces the expression of alpha-subunit reporter genes in either alpha T3-1 gonadotrope-derived or alpha TSH thyrotrope-derived cells. A deletion fragment containing nucleotides from -131 to +44 of the human alpha-subunit promoter is inhibited to a similar degree as a -244 to +44 fragment in alpha T3-1 cells. Nuclear proteins in alpha T3-1 cells bind two potential bHLH protein binding sites (E-boxes, alpha EB1 and alpha EB2) present in this fragment but not to mutations that specifically alter only these sequences. An antibody-specific for upstream stimulatory factor, a widely expressed bHLH-leucine zipper protein, is able to inhibit factor binding to the alpha EB2 sequences but not the alpha EB1 site. Mutating the alpha EB1 element of the alpha-subunit promoter decreases basal activity of this promoter to about 42% of control levels in alpha T3-1 cells. A mutation that abolishes upstream stimulatory factor binding, either alone or in combination with the alpha EB1 mutation, reduces basal activity of the promoter to approximately 21% of control levels in alpha T3-1 cells and abolishes the decrease in promoter activity seen when Id is overexpressed. These results demonstrate that the bHLH family of proteins are important regulators of alpha-subunit gene expression in pituitary cells.

Animals↗

PubMedDate not supplied

Immunohistochemical detection of glycoprotein hormone alpha subunit in somatoprolactinic and pure somatotroph adenomas.

Glycoprotein hormone alpha subunit (alpha SU) is expressed in nearly all thyreotroph adenomas and most gonadotrophinomas, but is less well documented in plurisecreting adenomas. We therefore examined the immunohistochemical (IHC) expression of alpha SU in a generally accepted model of plurisecreting adenomas (somatoprolactinic type) by comparison to a series of pure monosecreting somatotroph tumors. Fifty patients (32 females, 18 males) aged 15 to 68 years with clinical and/or biological acromegaly requiring adenomectomy were studied. Forty-five had clinical acromegaly and 5 had isolated amenorrhea and/or galactorrhea syndromes. Forty-eight of the 49 patients who had baseline assessments of plasma GH had a mean concentration of 5 ng/ml or more (normal value < 5). Fifteen of the 46 patients who had baseline measurements of plasma PRL had a prolactinemia value greater than 20 ng/ml (normal value < 20) but below 100 ng/ml, except for one patient. All the adenomas studied were positive by GH immunohistochemistry; 21 were immunostained by an antiPRL antibody and formed the "somatoprolactinic" (GH-PRL) group. Five of these 21 patients were male. The 12 female patients younger than 50 years had amenorrhea or galactorrhea, and one male patient complained of impotence. Eleven patients (9 females, 2 males) in this GH-PRL group had hyperprolactinemia. Sixteen of these GH-PRL adenomas were immunolabeled by alpha SU antiserum. The remaining 29 adenomas, which were immunonegative with the PRL antibody and formed the "somatotroph adenoma" (GH) group, were more frequent in male patients (13/29; 45%) compared to GH-PRL group. Eight amenorrhea or galactorrhea syndromes occurred among the 14 women younger than 50 years, 3 of whom had hyperprolactinemia. Thirteen of these 29 adenomas (45%) were immunopositive with alpha SU antibody. Compared to the GH group, the GH-PRL group had a significant higher frequency of amenorrhea and/or galactorrhea syndromes among women under 50 years (100% vs 57%; p < 0.01), as well as hyperprolactinemia (55% vs 15%; p < 0.01) and positive alpha SU immunoreactivity (76% vs 45%; p < 0.05). The frequency of extrasellar macroadenomas was not different according to PRL or alpha SU immunoreactivity. Thus, in this series of somatoprolactinic adenomas, alpha SU immunopositivity was slightly more frequent than in a control group of pure somatotroph adenomas. Moreover, hyperprolactinemia was more frequent in patients with GH-PRL adenomas, although the size of the pure and mixed adenomas was not different. These results suggest that hyperprolactinemia and/or alpha SU immunopositivity are more often associated with mixed GH-PRL adenomas.

Acromegaly↗

PubMed2001

AR suppresses transcription of the alpha glycoprotein hormone subunit gene through protein-protein interactions with cJun and activation transcription factor 2.

Previously, we reported that the AR directly suppressed transcription of the alpha glycoprotein hormone subunit (alphaGSU) gene in a ligand-dependent fashion while ER had no effect. Mutagenesis studies of the alphaGSU promoter indicated that two elements were required for AR-mediated suppression: the alpha basal element and tandem cAMP response elements (CREs). Because several members of the bZip family of transcriptional proteins can bind the CREs, we used several functional assays to determine whether AR interacts selectively with cJun, activation transcription factor 2 (ATF2), or CRE binding protein (CREB). When tested by cotransfection with AR, cJun and ATF2 specifically rescued androgen-mediated suppression of the alphaGSU-reporter construct in a gonadotrope-derived cell line. In contrast, cotransfected CREB displayed no activity in this rescue assay. In fact, overexpression of CREB alone diminished activity of the alphaGSU promoter, suggesting that the transcriptional activity normally conferred by the tandem CREs in gonadotropes requires their occupancy by cJun/ATF2 heterodimers. Binding assays carried out with a glutathione-S-transferase-AR fusion protein indicated that the receptor itself also displayed a clear preference for binding cJun and ATF2. Furthermore, we ruled out the possibility that AR suppressed activity of the alphaGSU promoter by reducing synthesis of these bZip proteins. Additional experiments suggested that phosphorylation of AR or histone acetylation are unlikely requirements for AR suppression of alphaGSU promoter activity. Thus, our data suggest that AR suppresses activity of the alphaGSU promoter through direct protein-protein interactions with cJun and ATF2.

Activating Transcription Factor 2↗

PubMed2006

Pituitary transcription factor Prop-1 stimulates porcine pituitary glycoprotein hormone alpha subunit gene expression.

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 beta subunit (FSHbeta) 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 alpha subunit (alphaGSU), and luteinizing hormone beta subunit (LHbeta). A series of deletion mutants of the porcine alphaGSU (up to -1059 bp) and LHbeta (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 alphaGSU and LHbeta promoters by Prop-1, which was found to activate the alphaGSU promoter of -1059/+12 bp up to 11.7-fold but not the LHbeta 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 alphaGSU, 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 alphaGSU 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 alphaGSU gene expression. These results, taken together with our previous finding that Prop-1 is a transcription factor for FSHbeta 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 alphaGSU and FSHbeta gene expressions.

AT-Hook Motifs↗

PubMed2001

Epidermal growth factor regulation of equine glycoprotein hormone alpha subunit expression in trophoblast cells.

Primates and equids are the only species known to express the placental glycoprotein hormone, chorionic gonadotropin (CG), a heterodimeric glycoprotein composed of an alpha subunit linked to a hormone-specific beta subunit. The regulatory mechanisms involved in the induction of equine glycoprotein alpha subunit gene expression have not been identified. Epidermal growth factor (EGF) receptor is known to transduce signals that alter a number of different cellular functions (cell proliferation, differentiation, hormone secretion, and gene regulation). In the present study, we investigated the regulation of the equine alpha subunit gene by EGF in trophoblasts. We found that 2800 base pairs of 5' flanking sequence from the equine alpha subunit promoter is sufficient for basal expression in human choriocarcinoma cells. Epidermal growth factor and phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C (PKC), increased transcriptional activity of the equine alpha subunit promoter (-2800/+21). These responses were blocked by pretreatment with bisindolylmaleimide-I, an inhibitor of PKC, suggesting an involvement of this pathway downstream of EGF. In addition, PD98059, an inhibitor of the extracellular signal-regulated kinase (ERK) pathway, completely blocked activation of the equine alpha promoter by PMA, suggesting that mitogen-activated protein kinase (MAPK) cascade was involved downstream of the PKC pathway. In conclusion, the EGF/PKC/MAPK pathway regulates equine glycoprotein alpha subunit gene expression through a distinct regulatory region (-2300 to -1900) in trophoblasts, while essential elements for basal expression appear to exist within the -2800 to -1900 region of the promoter.

Animals↗

PubMed1993

Estradiol modulates thyroid hormone regulation of the human glycoprotein hormone alpha subunit gene.

We have examined mechanisms of regulation of the human glycoprotein hormone alpha subunit gene by thyroid hormone (T3) and estradiol. Pituitary-derived GH3 cells were transiently transfected with chimeric constructs comprising between 1,500 and 98 base pairs of human alpha subunit gene 5'-flanking sequence fused to the bacterial gene encoding chloramphenicol acetyltransferase (h alpha CAT) and treated with T3 and estradiol, alone and in combination. In pituitary cells, 98 base pairs of alpha gene 5'-flanking sequence were sufficient to mediate both inhibition of alpha gene promoter activity by T3 and stimulation by estradiol; inhibition of the alpha promoter by T3 was antagonized by estradiol. Mutation of nucleotides essential for T3 receptor binding to the alpha gene thyroid hormone response element abolished the response of h alpha CAT expression to estradiol as well as T3. In contrast to pituitary GH3 cells, estradiol treatment alone had no effect on expression of either h alpha CAT or the endogenous alpha gene in JEG-3 choriocarcinoma cells cotransfected with a human thyroid hormone receptor expression vector, but estradiol antagonized suppression of both endogenous and transfected alpha promoter activity by T3. Gel mobility shift assays demonstrated specific binding of in vitro synthesized human estrogen receptor (ER) to the alpha gene thyroid hormone response element. These findings suggest that estradiol modulates expression of the human alpha subunit gene in pituitary and choriocarcinoma cells by direct binding of ER to the alpha gene promoter, and that interaction of ER with the alpha gene negative TRE accounts for the antagonistic effects of estradiol and T3.

Base Sequence↗

PubMed1980

Glycoprotein hormone alpha subunit secretion by pituitary adenomas: influence of external irradiation.

In ninety-nine patients with pituitary adenomas, forty-six with acromegaly, the serum level of the glycoprotein hormone alpha subunit was elevated in eighteen cases. Thirteen of these were acromegalic and one had an FSH-producing tumour. Alpha levels varied little during the day, from one day to the next and over a 6 month period. In twenty-five patients with a variety of other hypothalamic-pituitary disorders examined, one patient with a craniopharyngioma had a mildly elevated alpha level. External pituitary irradiation was followed by an acute and often transient fall in alpha level in several of these patients. Of the fifty-four patients with pituitary adenomas who had received external irradiation before testing, only five had elevated alpha subunit levels compared with thirteen patients of the forty-five who had not been irradiated. This difference in incidence of elevated alpha level was statistically significant (P less than 0.025). We conclude that external irradiation may reduce alpha subunit level chronically in many patients with pituitary adenoma.

Acromegaly↗

PubMed1990

Glycoprotein hormone alpha subunit in endocrine cells of human oxyntic mucosa. Studies on its relation to neuroendocrine tumors.

Expression of the alpha-subunit of glycoprotein hormones is an acquired feature of the endocrine cells of the oxyntic mucosa in patients with sustained serum levels of gastrin, and may be related to the hyperplasia-carcinoid sequence occurring in these patients. In the present study we have investigated the intragastric cellular localization and the circulating levels of alpha-subunit in a patient with Zollinger-Ellison syndrome. In this patient we have found that: 1) Endocrine cells accounted for 2.29% +/- 1.44% of the total oxyntic mucosal volume (normal value: 0.9% +/- 0.4%), with the ECL cells representing 63.22% +/- 10.9% of the total endocrine cell volume (normal value: 29.8 +/- 8.8%). 2) Cells immunoreactive for the alpha-subunit were found to correspond ultrastructurally to a subpopulation of enterochromaffin-like cells, indistinguishable from similar cells devoid of significant immuno-electron microscopic labeling. 3) Immunoreactive cells included a portion of oxyntic endocrine cells with punctate granules, a feature previously observed only in carcinoid tumors of the oxyntic mucosa. 4) In consecutive sections of freeze-dried vapor-fixed biopsies a fraction of alpha-subunit storing cells was found to co-express histamine. 5) The serum alpha-subunit levels were abnormally elevated and paralleled those of gastrin in a secretin-stimulation test. Analysis of similar curves in two other patients with Zollinger-Ellison syndrome, and five patients with hypergastrinemic atrophic gastritis, all presenting alpha-subunit containing oxyntic endocrine cells, showed significant alpha-subunit elevations only in the patients with ulcerogenic syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Gastric Mucosa↗

PubMedDate not supplied

A synthetic peptide corresponding to glycoprotein hormone alpha subunit residues 32-46 inhibits gonadotropin binding to receptor.

A synthetic peptide strategy was used to study structure-function relationships between residues 32 to 46 of the glycoprotein hormone alpha subunit (GPH alpha) and the testicular follicle-stimulating hormone (FSH) and luteinizing hormone (LH/hCG) receptors. A peptide amide corresponding to this region [GPH-alpha-(32-46)] inhibited both 125I-hFSH and 125I-hCG binding to their respective calf testis membrane receptors. The concentration at which GPH-alpha-(32-46) peptide amide inhibited FSH binding by 50% (IC50) was 36 microM, and for hCG it was 54 microM. GPH-alpha-(32-46) peptide amide also inhibited FSH-stimulated estradiol biosynthesis in cultured rat Sertoli cells. In order to determine the involvement of individual residues within this region of the glycoprotein hormone alpha subunit in receptor binding inhibitory activity, truncated and alanine-substituted peptide analogs were synthesized and tested in both FSH and hCG radioligand receptor competition assays. Based on the relative potency of each peptide, we conclude that Phe-33, Arg-35, Arg-42, Ser-43 and Lys-44 may be important, and Cys-32 is required, for inhibition of FSH and hCG binding to their respective receptor. Our results demonstrate involvement of the glycoprotein hormone alpha-subunit in receptor binding, identify residues 32 to 46 as a receptor binding domain, and define the relative importance of specific residues within this region of the alpha subunit for hormone-receptor interaction.

Amino Acid Sequence↗

PubMed2001

Molecular cloning of the cDNAs for pituitary glycoprotein hormone alpha subunits of two species of duck and their gene regulation.

The cDNAs encoding pituitary glycoprotein hormone alpha subunits (PGHalphas) of two species of duck (Muscovy duck, Cairina moschata and Pekin duck, Anas platyrhynchos domesticus) were cloned and sequenced to better understand the phylogenic diversity and evolution of PGHalpha molecules in vertebrates. Oligonucleotide primers were designed and used for reverse transcription PCR (RT-PCR) amplification of PGHalpha cDNA fragments from total cellular RNA of pituitary glands. The remaining sequences were completed by rapid amplification of the cDNA ends. The nucleotide sequence of isolated PGHalpha cDNA of both ducks are identical, including 81 bp of 5' untranslated region (UTR), 360 bp of coding region, and 272 bp of 3'-UTR followed by a 13 bp poly(A)(+) tract. The total number of amino acids deduced from the cDNA of the duck PGHalpha is 120 with a signal peptide of 24 amino acids and a mature protein of 96 amino acids. PGHalphas of the ducks (order Anseriformes) share 96% homology of amino acid sequence in signal peptide, and 100% homology in mature proteins with chicken, quail and turkey (order Galliformes). Our data thus demonstrate identical inter-order homology of PGHalpha mature protein in birds. Ten cysteine residues, presumably forming five disulfide bonds within the alpha subunit, and four proline residues, presumably responsible for folding of the molecule, are conserved in the alpha subunit of ducks. Northern blot analysis revealed that PGHalpha mRNA is expressed only in the pituitary. In order to study factors regulating the gene expression of PGHalpha mRNA, duck pituitary fragments were incubated with GnRH, TRH, testosterone, or triiodothyronine (T(3)). GnRH and TRH increased, while testosterone and T(3) decreased, PGHalpha mRNA levels. This is the first report in birds of TRH up-regulation and down-regulation by testosterone and T(3) under in vitro conditions. The present study demonstrates both ducks have the same cDNA nucleotide and deduced amino acid sequences in the PGHalpha subunit, exhibiting identical inter-genus homology within the family of Anatidae. The findings from mRNA expression work suggest that hypothalamic GnRH and TRH up-regulate, while testosterone and T(3) down-regulate, PGHalpha gene expression in ducks.

Amino Acid Sequence↗

PubMed1983

Immunocytochemical localization of the glycoprotein hormone alpha subunit in the median eminence of the mouse hypothalamus.

Immunoperoxidase staining was performed to localize glycoprotein hormone alpha subunit in mouse brain. Staining was found only in the median eminence with the use of ovine LH-alpha antiserum and was diffuse, not localized to fibers but to pericapillary areas. Absorption of the antiserum with bovine TSH-alpha subunit completely abolished the staining. These findings, in conjunction with our earlier studies in which alpha subunit messenger RNA was not detected in mouse brain, suggest that alpha subunit reaches the hypothalamus by retrograde diffusion from the pituitary.

Animals↗

PubMed1980

Serum glycoprotein hormone alpha subunit, hormone receptors and disease stage in patients with breast cancer.

The concentration of the common alpha subunit of the glycoprotein hormones was high in the serum of 21/56 (38%) of premenopausal patients and 22/106 (21%) of postmenopausal patients with primary breast cancer, at the time of presentation. 7/59 (12%) of patients with benign disease also had high alpha subunit levels. Tumour cytosol oestrogen and progesterone receptor status was determined in 80% of the patients with cancer, and there was a trend towards higher alpha levels in patients without receptors, but this was not statistically significant. In the premenopausal patients with cancer there was a significant correlation between alpha subunit level and disease stage, R = 0.47, P = 0.0001, but not in the postmenopausal patients. In view of the correlation with disease stage, high levels of alpha subunit in premenopausal patients with breast cancer at presentation with the primary tumour may indicate poor prognosis.

Adult↗

PubMed1998

Cloning of cDNAs for the pituitary glycoprotein hormone alpha subunit precursor molecules in three amphibian species, Bufo japonicus, Rana catesbeiana, and Cynops pyrrhogaster.

We have isolated cDNA clones encoding molecules of putative glycoprotein hormone alpha subunit precursors from their pituitary cDNA libraries for a toad, bullfrog and newt. The insert of the isolated toad cDNA was 562 bp long containing the 5'-untranlated, coding and 3'-untranslated regions of 38, 363 and 161 bp, respectively. The insert of the bullfrog cDNA was 604 bp long containing the 5'-untranslated, coding and 3'-untranslated regions of 70, 366, and 168 bp, respectively. In the newt, a composite cDNA sequence was estimated from four isolated partial clones. It was 694 bp long and contained the 5'-untranslated region of 89 bp, coding region of 366 bp, and 3'-untranslated region of 91 bp or longer. Amino acid sequences deduced from coding regions of the isolated clones showed that the signal peptides consist of 24 residues and the mature proteins of 96 (toad) or 97 residues (bullfrog and newt). In all three species, an insertion of an amino acid residue was found between residues 26 and 27 of the alpha subunit molecule sequence of all other vertebrate species studied. Interestingly, the percentage identities of the entire amino acid sequence between amphibian and mammalian (or avian) alpha subunits are lower than those between lungfish and mammalian (or avian) alpha subunits. This suggests that amino acid substitutions have occurred more frequently during the course of evolution in the alpha subunit molecule of amphibians than in that of other tetrapod vertebrates, although the biological significance of this is not known.

Amino Acid Sequence↗