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PubMed1995

Luteinizing hormone/chorionic gonadotropin bioactivity in the common marmoset (Callithrix jacchus) is due to a chorionic gonadotropin molecule with a structure intermediate between human chorionic gonadotropin and human luteinizing hormone.

Chorionic gonadotropin (CG), a pregnancy-specific heterodimeric hormone found in primates, is responsible for CL rescue with pregnancy maintenance. Of the primates, the human and baboon gene sequences are the only structures so far determined. In order to study the structure and function of CG in other primates, we have isolated and sequenced the coding regions for the two subunits of marmoset CG (mCG) by the reverse transcription/polymerase chain reaction method. Study of multiple clones confirmed a high degree of homology with the human sequences (88% and 80% for the alpha and beta nucleotide sequences, respectively). Marmoset CG alpha has an extra four amino acids compared to hCG alpha, whereas the mCG beta sequence has a 3-bp deletion that maintains the reading frame and C-terminal amino acid sequence. Most of the differences between hCG beta and mCG beta peptides occur in the C-terminal region, which includes the loss of two of the O-linked glycosylation consensus sequences and the presence of an N-linked glycosylation consensus sequence. When mCG alpha and beta were co-expressed in CHO cells, assembly of biologically active hormone was confirmed by induced steroid secretion by MA10 cells. Partially purified mCG beta was used to raise anti-mCG antibodies. To date, an antibody has been obtained that is capable of detecting recombinant mCG beta, recombinant mCG dimer, and mCG dimer secreted by cultured marmoset trophoblast. Marmoset CG alpha and beta were also detectable at the transcriptional level in cultured trophoblast by in situ hybridization. This suggests that the LH/CG bioactivity reported from marmoset placentae and embryos is due to a molecule with structural features common to hLH (glycosylation pattern) and hCG (CG beta C-terminal structure).

Amino Acid Sequence↗
PubMed1989

Prenatal screening for Down syndrome with maternal serum human chorionic gonadotropin levels.

Human chorionic gonadotropin levels in midtrimester pregnancies may be predictive of Down syndrome. A commercially available enzyme immunoassay kit was used to measure the beta-subunit of human chorionic gonadotropin in maternal sera from 38 Down syndrome pregnancies and 114 gestational age matched controls. The human chorionic gonadotropin levels were also assayed in 236 normal sera and plasma samples to determine normative values and appropriate individual corrections. Serum and plasma human chorionic gonadotropin levels are closely correlated and are stable at room temperature, during refrigeration, and throughout freeze-thaw cycles. There is no correlation between the human chorionic gonadotropin level and maternal age, weight, or race. However, the human chorionic gonadotropin level decreases with each week of gestation from 15 to 19 weeks. Medians for each week of gestation were established to account for this variable. Up to 63% of the Down syndrome pregnancies were detected with a cutoff of 2.0 multiples of the normal median. A computational combination of human chorionic gonadotropin and maternal serum alpha-fetoprotein testing will detect additional Down syndrome pregnancies and decrease the false-positive rate. The measurement of human chorionic gonadotropin appears to be a valuable addition to maternal serum alpha-fetoprotein screening programs that can significantly increase the proportion of Down syndrome cases diagnosed.

Blood Specimen Collection↗
PubMedDate not supplied

Treatment of cystic ovaries in dairy cattle using human chorionic gonadotropin or a compound consisting of human chorionic gonadotropin with progesterone.

The present study deals with a comparison of HCG and HCG + P (N) as to their efficiency in the treatment of the ovarian cystic syndrome in dairy cattle (263 cases). The intervals between treatment and first oestrus were the same in both groups (22 vs. 23 days), whereas the cows of the HCG-group conceived earlier (29 days) than the cows of group N (36 days), the difference was not, however, significant. The conception rate after first AI was almost significantly higher in the HCG-group (67% vs. 49%, P less than 0.05). The number of inseminations required per pregnancy was also almost significantly lower in the HCG-group (1.22 vs. 1.48, P less than 0.05). The conclusions drawn were the following: the treatment of ovarian cysts with HCG was somewhat more effective than a treatment with N, thus confirming the previous results achieved under Finnish conditions.

Animals↗
PubMed1977

Clinical relevance of research on the structure of human chorionic gonadotropin.

Human chorionic gonadotropin (hCG) has been studied extensively over the past 10 years, and some structural correlates of its chemical, biological, and immunologic properties have been defined. A review of these observations and their relevance to clinical applications of methods for detecting hCG is presented.

Carbohydrates↗
PubMed1980

In vitro induction of murine suppressor T-cells by human chorionic gonadotropin.

Human chorionic gonadotropin (HCG) has previously been considered to be immunosuppressive and, thus, by prohibiting maternal rejection of the fetal transplant, to be one of the factors responsible for the successful outcome of pregnancy. The mechanism by which HCG exerts its pregnancy retaining effect is, however, as yet unknown. The present study shows that HCG has the capacity in mice of inducing lymphocytes which are subsequently competent to depress a polyclonal antibody response induced by different B cell mitogens. It is therefore suggested that HCG may exert its feto-protective action by inducing suppressor T cells. These lymphocytes would thus prevent the activation of cells which are responsible for transplant rejection.

Animals↗
PubMed1982

Sex-dependent induction of human suppressor T cells by chorionic gonadotropin.

Human chorionic gonadotropin (hCG) in physiological retroplacental concentration has been shown to induce human female lymphocytes which suppress the proliferation and differentiation of B cells stimulated by purified protein derivative of tuberculin. To test whether the hCG-induced suppression was sex dependent parallel experiments using female and male peripheral lymphocytes were performed. hCG did not induce cells capable of suppressing purified protein derivative induced B cell proliferation in lymphocytes from males, which was in contrast to lymphocytes from females where a statistically significant suppression was found. A similar hCG-induced suppressive effect was found before menarche, after the menopause and in two patients with Turner's syndrome, suggesting that a gene(s) on the Y chromosome exerts a regulatory function and thus prevents the hormone from inducing suppressor T cells.

Aging↗
PubMed1998

Identification of new genes differentially expressed in breast carcinoma cells treated with human chorionic gonadotropin.

Human chorionic gonadotropin (hCG) inhibits the growth of human breast epithelial cells MCF-7. Differential display was utilized for analyzing RNA of hCG-treated MCF-7 cells in order to determine whether this effect was mediated by specific gene activation or repression. Three cDNA clones, 19, 29 and 44, were differentially expressed in treated cells. Clone 44, whose sequence matched a gene expressed in dexamethasone-treated T-cell hybridoma, was increased by approximately 4-fold, while clones 19 and 29 were markedly reduced by hCG treatment. These latter ones were considered to be novel genes, since no homology was found in the gene-bank. Our results indicate that hCG influences gene expression in mammary epithelial cells, supporting its potential role in breast cancer prevention and therapy.

Blotting, Northern↗
PubMed2000

Preparation and analysis of the common urinary forms of human chorionic gonadotropin.

Human chorionic gonadotropin (hCG) is the hormone of pregnancy and forms the basis of all pregnancy tests as well as diagnostic assays for a variety of pathological states including certain types of cancers and some diseases of pregnancy and genetic abnormalities. In recent years, the discovery of the diagnostic utility of measurement of the free subunits and fragments of the hormone, especially in urine, has proven of special use for diagnosis of very early pregnancy loss, an important phenomenon related to infertility, as well as part of screening programs for Down Syndrome and gynecological cancers. This article summarizes existing and new methods for the preparation of hCG, its subunits, and the beta core fragment from urinary sources. The methods for proper analyses of these materials are also described to enable investigators to prepare and analyze these materials in various quantities in their own laboratories.

Chorionic Gonadotropin↗
PubMed1998

In vivo regulation of the insulin-like growth factor system of mitogens by human chorionic gonadotropin.

Human chorionic gonadotropin (hCG) is a differentiating agent and chemopreventive in rat DMBA-induced breast carcinogenesis. Insulin-like growth factors (IGFs) are potent mitogens for breast cancer cells. We report that the administration of hCG to female rats resulted in a significant increase in serum IGFBP-3 levels at doses greater than 10 UI and a significant decrease in serum IGF-I levels. Northern blot analysis revealed that hCG inhibited hepatic and mammary IGF-I gene expression at doses greater than 10 UI. Mammary IGFBP-5 and IGFBP-2 gene expression significantly increased at high doses of hCG while IGFBP-4 slightly decreased. Treatments greater than 10 UI of hCG resulted in a significant suppression of mammary IGFBP-3 and IGF-I receptor expression. Since IGFs are potent mitogens and antiapoptotic agents for breast cancer, this newly described activity of hCG may contribute to its antiproliferative properties, particularly with regard to the differentiation and inhibition of mammary tumours seen in animal models.

Animals↗
PubMed2001

Identification of beta subunit of the rhesus monkey chorionic gonadotropin (rmCG).

Chorionic gonadotropin (CG) is a placental derived hormone that plays a crucial role in successful implantation and establishment of early pregnancy in the primates. The rhesus monkey was chosen as a model to understand the feasibility of developing human DNA immuno-contraceptive. The coding region of rhesus monkey CG beta-subunit (rmCGbeta) was isolated by the TDRT-PCR method. The nucleotide sequence including the leader peptide was 499 nucleotide long and encoded 166 amino acids. In comparing with the previous known primates CG beta-subunits, the rmCGbeta was the highest degree of homology with baboon CG beta-subunit at the deduced amino acid sequence (94%), 79.5% homology with human CG beta-subunit and 70.4% homology with marmoset monkey CG beta-subunit. The eukaryotic expression vector pCMV4-rmCGbeta inserted full-coding cDNA sequence of rmCGbeta was constructed, and the expression of rmCG beta-subunit in HeLa cells transient expressing system in vitro and BALB/c mice in vivo was determined. The results demonstrated that the recombinant PCMV4-rmCGbeta eukaryotic expression vector could express rmCG beta-subunit in vitro and in vivo.

Amino Acid Sequence↗
PubMed1999

Lysozyme and RNases as anti-HIV components in beta-core preparations of human chorionic gonadotropin.

Human chorionic gonadotropin (hCG) preparations contain activity against HIV type 1 (HIV-1). However, there has been controversy about whether some biological activities of hCG beta-subunit (hCGbeta) preparations are caused by the beta-subunit itself or other proteins present in the preparations. We report here the purification, characterization, and identification of three enzymes with anti-HIV activity present in the beta-core fraction of hCGbeta prepared from the urine of pregnant women. The N-terminal amino acid sequence of one protein is identical to human urinary lysozyme C, and those of the other two are identical to human RNase A and urinary RNase U. We thus refer to these proteins as AVL (antiviral lysozyme) and AVR (antiviral RNases). In addition to HIV-1 inhibition, AVL is capable of lysing Micrococcus lysodeikticus. AVR digests a variety of RNA substrates, including RNA from HIV-1-infected cells. We also find that lysozyme from chicken egg white, human milk, and human neutrophils and RNase A from bovine pancreas possess activity against HIV-1. These findings may offer additional strategies for the treatment of HIV-1 infection.

Amino Acid Sequence↗
PubMed1999

Structure, pathology and function of the N-linked sugar chains of human chorionic gonadotropin.

Human chorionic gonadotropin (hCG) contains five acidic N-linked sugar chains, which are derived from three neutral oligosaccharides by sialylation. Each of the two subunits (hCGalpha and hCGbeta) of hCG contain two glycosylated Asn residues. Glycopeptides, each containing a single glycosylated Asn, were obtained by digestion of hCGalpha with trypsin, and of hCGbeta with chymotrypsin and lysyl endopeptidase. Comparative study of the sugar chains of the four glycopeptides revealed the occurrence of site-directed glycosylation. Studies of the sugar chains of hCGs, purified from urine of patients with various trophoblastic diseases, revealed that choriocarcinoma hCGs contain sialylated or non-sialylated forms of eight neutral oligosaccharides. In contrast, hCGs from invasive mole patients contain sialyl derivatives of five neutral oligosaccharides. The structural characteristics of the five neutral oligosaccharides, detected in choriocarcinoma hCGs but not in normal placental hCGs, indicate that N-acetylglucosaminyltransferase IV (GnT-IV) is abnormally expressed in the malignant cells. This supposition was confirmed by molecular biological study of GnT-IV in placenta and choriocarcinoma cell lines. The appearance of tumor-specific sugar chains in hCG has been used to develop a diagnostic method of searching for malignant trophoblastic diseases. In addition, a summary of the current knowledge concerning the functional role of N-linked sugar chains in the expression of the hormonal activity of hCG has been presented.

Animals↗
PubMed1986

Use of synthetic peptides as immunogens for developing a vaccine against human chorionic gonadotropin.

Human chorionic gonadotropin (hCG) is a glycoprotein hormone produced by the placental trophoblast soon after conception and is essential for successful gestation in women. A vaccine against this hormone has been developed for the purposes of birth control and the treatment of hormone-related diseases. Synthetic peptides representing the native primary structure of the hCG beta subunit have been coupled to protein carriers to produce immunogens. Several peptides, representing varying lengths from the C-terminus of the beta subunit, were synthesized and their ability to elicit antibodies reactive to hCG and able to neutralize hCG activity in vivo was tested. A peptide representing the 37 amino acids of the C-terminal end of the beta subunit was selected as the vaccine antigen and diphtheria toxoid was selected as the carrier for the first prototype vaccine. Procedures for coupling a specified number of peptide molecules to each carrier molecule in a reproducible fashion were developed. The immunogen is mixed with an adjuvant compound and the mixture administered in an oil-in-water emulsion. Significant levels of antibodies to hCG have been elicited in several species and a marked reduction in the fertility of immunized baboons has been observed. Extensive evaluations of vaccine safety have been conducted and Phase I clinical trials have been proposed to test its utility for human birth control. Possible applications of the hCG vaccine to health problems other than birth control are being considered.

Adjuvants, Immunologic↗
PubMed1987

Development of monoclonal antibodies directed against different epitopes of human chorionic gonadotropin.

Human chorionic gonadotropin (HCG) is a 40,000 dalton glycoprotein composed of two non-identical alpha- and beta-subunits. HCG and other related pituitary hormones, such as human luteinizing hormones (HLH), human follicle stimulating hormone (HFSH), and human thyroid stimulating hormone (HTSH), consist of nearly identical alpha-chains. However, their beta-chains show a variable degree of amino acid sequence homology. Detection and subsequent quantitative determination of HCG in human biological fluids is useful in early diagnosis of pregnancy and in monitoring of tumor patients. For these applications monoclonal antibodies (McAbs) with defined specificity are required. Several hybridomas secreting McAbs to HCG have been isolated. The hybridoma cells have been developed by fusion of NS1 myeloma cells with spleen cells of Balb/C mice immunized with HCG. With the aid of an enzyme linked immunosorbent assay, six McAbs were characterized. McAbs A-73, A-76 and A-112 recognize an epitope present on the alpha-HCG subunit. McAbs B-68, B-69 and B-106 recognize an antigenic determinant associated with the beta-HCG subunit. Two of these McAbs: B-68 and B-69 are directed against an epitope on the B subunit specific to the HCG molecule and B-106 McAb towards an epitope common to HCG, TSH, LH and FSH molecule. In a hemagglutination test, only the A-73 McAb is capable of inducing agglutination of sheep red blood cells coated with HCG, thus suggesting that this McAb recognizes a repeating epitope on the alpha-HCG molecule.

Animals↗
PubMed1986

Regulation of serum testosterone in men with steroid sulfatase deficiency: response to human chorionic gonadotropin.

Human chorionic gonadotropin (hCG; 5000 IU) was administered to 6 control men and 6 patients with recessive x-linked ichthyosis (RXLI) with verified 3 beta-hydroxysteroid sulfate sulfatase (3 beta-HSS) deficiency in their skin biopsy samples. Concentrations of steroids and their sulfate conjugates were determined in peripheral serum specimens collected a day before and 4 days after hCG administration. Testosterone concentrations were identical in patients and controls. Baseline serum LH concentrations were also identical in the 2 groups showing that there were no major differences in the regulation of the hypothalamic-pituitary-gonadal axis. The significantly increased (31-82%) serum concentrations of sulfated pregnenolone, 17-hydroxypregnenolone, dehydroepiandrosterone and 5-androstene-3 beta,17 beta-diol in patients compared with controls indicated that their circulating concentrations were regulated by 3 beta-HSS. This is in line with the fact that the baseline concentrations of the same unconjugated steroids were significantly lower (32-90%) in patients with RXLI, suggesting that a proportion of these circulating steroids were derived from the corresponding sulfated precursors. The response patterns and actual concentrations of testosterone, 17-hydroxyprogesterone and estradiol were similar in the patients and the controls after hCG. The decreased concentrations of testosterone sulfated at carbon 17 under baseline conditions and after hCG in patients with RXLI remains enigmatic. In conclusion, testosterone production and the response to hCG seem to be identical in patients with RXLI and controls despite the fact that significant differences were observed in the circulating concentrations of several unconjugated and sulfated testosterone precursors.

Adult↗
PubMed1999

Epitope analysis and molecular modeling reveal the topography of the C-terminal peptide of the beta-subunit of human chorionic gonadotropin.

Human chorionic gonadotropin (hCG) belongs to a family of heterodimeric glycoprotein hormones that share a common alpha-subunit and a hormone-specific beta-subunit. Among the gonadotropin beta-subunits, greater than 85% homology exists between lutropin (hLH)beta and hCGbeta in their first 114 amino acid residues. However, unlike hLHbeta, hCGbeta contains a 31-amino acid hydrophilic stretch at its carboxyl end (CTPbeta: C-terminal peptide). Although the crystal structure of deglycosylated hCG has been solved, the topography of CTPbeta remains unknown. In this study, we have attempted to define the topology of CTPbeta using mAb probes. We investigated three epitopes on hCGalpha, which are hidden in the hCGalphabeta dimer. However, these epitopes are not hidden in hLH, which has a similar subunit interface to that of hCG, but lacks CTPbeta. This suggested that these epitopes are not masked at the subunit interface of hLH or hCG. Hence, we hypothesized that, in the case of hCG, these epitopes are masked by the CTPbeta. Consistent with this view, several treatments of hCG that removed CTPbeta unmasked these epitopes and enhanced their reactivity with the corresponding mAbs. In order to localise the position of CTPbeta on the alpha-subunit, we used an epitope-mapping strategy [N. Venkatesh & G. S. Murthy (1997) J. Immunol. Methods 202, 173-182] based on differential susceptibility of epitopes to covalent modifications. This enabled us to predict the possible topography of CTPbeta. Further, we were also able to build a model of CTPbeta, completely independently of the epitope-mapping studies, using a homology-based modeling approach [S. Krishnaswamy, I. Lakshminarayanan & S. Bhattacharya (1995) Protein Sci. 4 (Suppl. 2), 86-97]. Results obtained from these two different approaches (epitope analysis and homology modeling) agree with each other and indicate that portions of CTPbeta are in contact with hCGalpha in the native hCG dimer.

Animals↗