1
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Nguyen TMD, Klett D, Combarnous Y. Undissociable chemically cross-linked and single-chain gonadotropins. Theriogenology 2023; 198:250-255. [PMID: 36621134 DOI: 10.1016/j.theriogenology.2022.12.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 12/20/2022] [Accepted: 12/22/2022] [Indexed: 12/24/2022]
Abstract
Undissociable gonadotropins can be obtained either by chemical cross-linking of the natural heterodimeric hormones or by expressing recombinant single-chain molecules through the fusion of their α and β polypeptide sequences. These undissociable hormones are not more active than their natural heterodimeric counterparts indicating that the β-subunit seatbelt embracing the α-subunit ensures the αβ heterodimer stability in physiological conditions. The main interests of single-chain gonadotropins are that 1/only one single plasmid is required to produce an active recombinant hormone, 2/the two subunits' domains are constantly present in equal amounts and 3/they remain in close proximity even at low concentration for forming the hormone bioactive 3D structure. These undissociable gonadotropins have been shown to exhibit excellent stability and activity but they have not yet been commercialized probably because of immunogenicity risks and cost of production. Nevertheless, they might be used as a basis for the development of chemically simpler and cheaper ligands of LH and FSH receptors.
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Affiliation(s)
- Thi Mong Diep Nguyen
- INRAe, CNRS Unit of Reproductive Physiology and Behaviour, 37380, Nouzilly, France; Faculty of Natural Sciences, Quy Nhon University, Quy Nhon, 820000, Viet Nam
| | - Danièle Klett
- INRAe, CNRS Unit of Reproductive Physiology and Behaviour, 37380, Nouzilly, France
| | - Yves Combarnous
- INRAe, CNRS Unit of Reproductive Physiology and Behaviour, 37380, Nouzilly, France.
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2
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Kumar TR. Fshb Knockout Mouse Model, Two Decades Later and Into the Future. Endocrinology 2018; 159:1941-1949. [PMID: 29579177 PMCID: PMC5888209 DOI: 10.1210/en.2018-00072] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 03/02/2018] [Indexed: 12/20/2022]
Abstract
In 1997, nearly 20 years ago, we reported the phenotypes of follicle-stimulating hormone (FSH) β (Fshb) null mice. Since then, these mice have been useful for various physiological and genetic studies in reproductive and skeletal biology. In a 2009 review titled "FSHβ Knockout Mouse Model: A Decade Ago and Into the Future," I summarized the need for and what led to the development of an FSH-deficient mouse model and its applications, including delineation of the emerging extragonadal roles of FSH in bone cells by using this genetic model. These studies opened up exciting avenues of research on osteoporosis and now extend into those on adiposity in postmenopausal women. Here, I summarize the progress made with this mouse model since 2009 with regard to FSH rerouting in vivo, deciphering the role of N-glycosylation on FSHβ, roles of FSH in somatic-germ cell interactions in gonads, and provide a road map that is anticipated to emerge in the near future. Undoubtedly, the next 10 years should be an even more exciting time to explore the fertile area of FSH biology and its implications for basic and clinical reproductive physiology research.
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Affiliation(s)
- T Rajendra Kumar
- Department of Obstetrics and Gynecology, Division of Reproductive Sciences, University of Colorado at Denver, Anschutz Medical Campus, Aurora, Colorado
- Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, University of Colorado at Denver, Anschutz Medical Campus, Aurora, Colorado
- Correspondence: T. Rajendra Kumar, PhD, Edgar L. and Patricia M. Makowski Professor, Department of Obstetrics and Gynecology, University of Colorado Anschutz Medical Campus, 12700 East 19th Avenue, RC-2 Complex, 15-3000B, Aurora, Colorado 80045. E-mail:
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3
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Ben-Menahem D. Preparation, characterization and application of long-acting FSH analogs for assisted reproduction. Theriogenology 2018; 112:11-17. [DOI: 10.1016/j.theriogenology.2017.08.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 08/02/2017] [Accepted: 08/23/2017] [Indexed: 10/18/2022]
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4
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Wang H, May J, Butnev V, Shuai B, May JV, Bousfield GR, Kumar TR. Evaluation of in vivo bioactivities of recombinant hypo- (FSH 21/18) and fully- (FSH 24) glycosylated human FSH glycoforms in Fshb null mice. Mol Cell Endocrinol 2016; 437:224-236. [PMID: 27561202 PMCID: PMC5048586 DOI: 10.1016/j.mce.2016.08.031] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 08/21/2016] [Accepted: 08/21/2016] [Indexed: 10/21/2022]
Abstract
The hormone - specific FSHβ subunit of the human FSH heterodimer consists of N-linked glycans at Asn7 and Asn24 residues that are co-translationally attached early during subunit biosynthesis. Differences in the number of N-glycans (none, one or two) on the human FSHβ subunit contribute to macroheterogeneity in the FSH heterodimer. The resulting FSH glycoforms are termed hypo-glycosylated (FSH21/18, missing either an Asn24 or Asn7 N-glycan chain on the β - subunit, respectively) or fully glycosylated (FSH24, possessing of both Asn7 and Asn24 N-linked glycans on the β - subunit) FSH. The recombinant versions of human FSH glycoforms (FSH21/18 and FSH24) have been purified and biochemically characterized. In vitro functional studies have indicated that FSH21/18 exhibits faster FSH- receptor binding kinetics and is much more active than FSH24 in every assay tested to date. However, the in vivo bioactivity of the hypo-glycosylated FSH glycoform has never been tested. Here, we evaluated the in vivo bioactivities of FSH glycoforms in Fshb null mice using a pharmacological rescue approach. In Fshb null female mice, both hypo- and fully-glycosylated FSH elicited an ovarian weight gain response by 48 h and induced ovarian genes in a dose- and time-dependent manner. Quantification by real time qPCR assays indicated that hypo-glycosylated FSH21/18 was bioactive in vivo and induced FSH-responsive ovarian genes similar to fully-glycosylated FSH24. Western blot analyses followed by densitometry of key signaling components downstream of the FSH-receptor confirmed that the hypo-glycosylated FSH21/18 elicited a response similar to that by fully-glycosylated FSH24 in ovaries of Fshb null mice. When injected into Fshb null males, hypo-glycosylated FSH21/18 was more active than the fully-glycosylated FSH24 in inducing FSH-responsive genes and Sertoli cell proliferation. Thus, our data establish that recombinant hypo-glycosylated human FSH21/18 glycoform elicits bioactivity in vivo similar to the fully-glycosylated FSH. Our studies may have clinical implications particularly in formulating FSH-based ovarian follicle induction protocols using a combination of different human FSH glycoforms.
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Affiliation(s)
- Huizhen Wang
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Jacob May
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Viktor Butnev
- Department of Biological Sciences, Wichita State University, Wichita, KS 67260, USA
| | - Bin Shuai
- Department of Biological Sciences, Wichita State University, Wichita, KS 67260, USA
| | - Jeffrey V May
- Department of Biological Sciences, Wichita State University, Wichita, KS 67260, USA
| | - George R Bousfield
- Department of Biological Sciences, Wichita State University, Wichita, KS 67260, USA
| | - T Rajendra Kumar
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS 66160, USA; Center for Reproductive Sciences, Institute for Reproductive Health and Regenerative Medicine, University of Kansas Medical Center, Kansas City, KS 66160, USA; Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, KS 66160, USA; Department of Neurosurgery, University of Kansas Medical Center, Kansas City, KS 66160, USA; Division of Reproductive Sciences, Department of Obstetrics & Gynecology, University of Colorado Denver-Anschutz Medical Campus, Aurora, CO 80045, USA.
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5
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Kleinau G, Kalveram L, Köhrle J, Szkudlinski M, Schomburg L, Biebermann H, Grüters-Kieslich A. Minireview: Insights Into the Structural and Molecular Consequences of the TSH-β Mutation C105Vfs114X. Mol Endocrinol 2016; 30:954-64. [PMID: 27387040 DOI: 10.1210/me.2016-1065] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Naturally occurring thyrotropin (TSH) mutations are rare, which is also the case for the homologous heterodimeric glycoprotein hormones (GPHs) follitropin (FSH), lutropin (LH), and choriogonadotropin (CG). Patients with TSH-inactivating mutations present with central congenital hypothyroidism. Here, we summarize insights into the most frequent loss-of-function β-subunit of TSH mutation C105Vfs114X, which is associated with isolated TSH deficiency. This review will address the following question. What is currently known on the molecular background of this TSH variant on a protein level? It has not yet been clarified how C105Vfs114X causes early symptoms in affected patients, which are comparably severe to those observed in newborns lacking any functional thyroid tissue (athyreosis). To better understand the mechanisms of this mutant, we have summarized published reports and complemented this information with a structural perspective on GPHs. By including the ancestral TSH receptor agonist thyrostimulin and pathogenic mutations reported for FSH, LH, and choriogonadotropin in the analysis, insightful structure function and evolutionary restrictions become apparent. However, comparisons of immunogenicity and bioactivity of different GPH variants is hindered by a lack of consensus for functional analysis and the diversity of used GPH assays. Accordingly, relevant gaps of knowledge concerning details of GPH mutation-related effects are identified and highlighted in this review. These issues are of general importance as several previous and recent studies point towards the high impact of GPH variants in differential signaling regulation at GPH receptors (GPHRs), both endogenously and under diseased conditions. Further improvement in this area is of decisive importance for the development of novel targeted therapies.
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Affiliation(s)
- Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology (G.K., L.K., H.B.), Charité-Universitätsmedizin, Berlin, 13353 Germany; Institute of Experimental Endocrinology (J.K., L.S.), Charité-Universitätsmedizin Berlin, 13353 Germany; Trophogen, Inc (M.S.), Rockville, Maryland 20850; and Department of Pediatric Endocrinology and Diabetes (A.G.-K.), Charité-Universitätsmedizin, Berlin, 13353 Germany
| | - Laura Kalveram
- Institute of Experimental Pediatric Endocrinology (G.K., L.K., H.B.), Charité-Universitätsmedizin, Berlin, 13353 Germany; Institute of Experimental Endocrinology (J.K., L.S.), Charité-Universitätsmedizin Berlin, 13353 Germany; Trophogen, Inc (M.S.), Rockville, Maryland 20850; and Department of Pediatric Endocrinology and Diabetes (A.G.-K.), Charité-Universitätsmedizin, Berlin, 13353 Germany
| | - Josef Köhrle
- Institute of Experimental Pediatric Endocrinology (G.K., L.K., H.B.), Charité-Universitätsmedizin, Berlin, 13353 Germany; Institute of Experimental Endocrinology (J.K., L.S.), Charité-Universitätsmedizin Berlin, 13353 Germany; Trophogen, Inc (M.S.), Rockville, Maryland 20850; and Department of Pediatric Endocrinology and Diabetes (A.G.-K.), Charité-Universitätsmedizin, Berlin, 13353 Germany
| | - Mariusz Szkudlinski
- Institute of Experimental Pediatric Endocrinology (G.K., L.K., H.B.), Charité-Universitätsmedizin, Berlin, 13353 Germany; Institute of Experimental Endocrinology (J.K., L.S.), Charité-Universitätsmedizin Berlin, 13353 Germany; Trophogen, Inc (M.S.), Rockville, Maryland 20850; and Department of Pediatric Endocrinology and Diabetes (A.G.-K.), Charité-Universitätsmedizin, Berlin, 13353 Germany
| | - Lutz Schomburg
- Institute of Experimental Pediatric Endocrinology (G.K., L.K., H.B.), Charité-Universitätsmedizin, Berlin, 13353 Germany; Institute of Experimental Endocrinology (J.K., L.S.), Charité-Universitätsmedizin Berlin, 13353 Germany; Trophogen, Inc (M.S.), Rockville, Maryland 20850; and Department of Pediatric Endocrinology and Diabetes (A.G.-K.), Charité-Universitätsmedizin, Berlin, 13353 Germany
| | - Heike Biebermann
- Institute of Experimental Pediatric Endocrinology (G.K., L.K., H.B.), Charité-Universitätsmedizin, Berlin, 13353 Germany; Institute of Experimental Endocrinology (J.K., L.S.), Charité-Universitätsmedizin Berlin, 13353 Germany; Trophogen, Inc (M.S.), Rockville, Maryland 20850; and Department of Pediatric Endocrinology and Diabetes (A.G.-K.), Charité-Universitätsmedizin, Berlin, 13353 Germany
| | - Annette Grüters-Kieslich
- Institute of Experimental Pediatric Endocrinology (G.K., L.K., H.B.), Charité-Universitätsmedizin, Berlin, 13353 Germany; Institute of Experimental Endocrinology (J.K., L.S.), Charité-Universitätsmedizin Berlin, 13353 Germany; Trophogen, Inc (M.S.), Rockville, Maryland 20850; and Department of Pediatric Endocrinology and Diabetes (A.G.-K.), Charité-Universitätsmedizin, Berlin, 13353 Germany
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6
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Kleinau G, Neumann S, Grüters A, Krude H, Biebermann H. Novel insights on thyroid-stimulating hormone receptor signal transduction. Endocr Rev 2013; 34:691-724. [PMID: 23645907 PMCID: PMC3785642 DOI: 10.1210/er.2012-1072] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The TSH receptor (TSHR) is a member of the glycoprotein hormone receptors, a subfamily of family A G protein-coupled receptors. The TSHR is of great importance for the growth and function of the thyroid gland. The TSHR and its endogenous ligand TSH are pivotal proteins with respect to a variety of physiological functions and malfunctions. The molecular events of TSHR regulation can be summarized as a process of signal transduction, including signal reception, conversion, and amplification. The steps during signal transduction from the extra- to the intracellular sites of the cell are not yet comprehensively understood. However, essential new insights have been achieved in recent years on the interrelated mechanisms at the extracellular region, the transmembrane domain, and intracellular components. This review contains a critical summary of available knowledge of the molecular mechanisms of signal transduction at the TSHR, for example, the key amino acids involved in hormone binding or in the structural conformational changes that lead to G protein activation or signaling regulation. Aspects of TSHR oligomerization, signaling promiscuity, signaling selectivity, phenotypes of genetic variations, and potential extrathyroidal receptor activity are also considered, because these are relevant to an understanding of the overall function of the TSHR, including physiological, pathophysiological, and pharmacological perspectives. Directions for future research are discussed.
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Affiliation(s)
- Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, Ostring 3, Augustenburger Platz 1, 13353 Berlin, Germany.
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7
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Kumar TR. FSHbeta knockout mouse model: a decade ago and into the future. Endocrine 2009; 36:1-5. [PMID: 19387872 PMCID: PMC4074305 DOI: 10.1007/s12020-009-9199-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Revised: 02/24/2009] [Accepted: 04/09/2009] [Indexed: 10/20/2022]
Abstract
In 1997, more than 10 years ago now, we first reported the phenotypes of follicle stimulating hormone (FSH) beta null mice. Since then, these mice have been useful for various physiological and genetic studies in reproductive biology. More recently, extra-gonadal functions of FSH have been discovered in bone. These studies opened up exciting avenues of new research on osteoporosis in postmenopausal women. Several genomics and proteomics tools and novel strategies to spatio-temporally restricting gene expression in vivo are available now. It is hoped that with the aid of these and other emerging technologies, an integrated network of FSH signaling pathways in various tissues would emerge in the near future. Undoubtedly, the coming 10 years should be more exciting to explore this "fertile" area of reproductive physiology research.
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Affiliation(s)
- T Rajendra Kumar
- Department of Molecular, University of Kansas Medical Center, Kansas City, KS 66160, USA.
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8
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Ben-Menahem D, Grotjan HE. Strategies for construction of luteinizing hormone beta subunit analogs with carboxyl terminal extensions in non-primate, non-equid mammalian species. Mol Cell Endocrinol 2007; 260-262:205-11. [PMID: 17092639 DOI: 10.1016/j.mce.2005.11.054] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2005] [Accepted: 11/21/2005] [Indexed: 10/23/2022]
Abstract
Chorionic gonadotropins (CG) are unique because they have a carboxyl terminal peptide (CTP) extension on their beta subunits that prolongs circulatory survival. CGbeta genes from the human being and horse have evolved from ancestral luteinizing hormone (LH) beta genes by different pathways that involve deletions that change the reading frames and yield a CTP. Here we further review our previous analysis, aimed at determining whether LHbeta genes in non-primate, non-equid species inherently possess DNA sequences that encode CTP-like domains. In multiple mammalian species, simple frame-shift mutations using either the human or equine CGbeta gene as a model can be used to construct LHbeta analogs with putative CTP domains. Furthermore, DNA sequences from mammalian LHbeta genes can be aligned to maximize similarity with CGbeta genes in order to devise more refined strategies for construction of CTP-bearing LHbeta analogs as exemplified in the bovine case. Thus, mammalian LHbeta genes have DNA sequences that can be potentially expressed in order to construct CTP-bearing glycoprotein hormone analogs.
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Affiliation(s)
- D Ben-Menahem
- Department of Clinical Pharmacology, Ben-Gurion University, Faculty of Health Sciences, P.O.B. 653, Beer-Sheva 84105, Israel.
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9
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Braw-Tal R, Pen S, Grinberg M, Nakav S, Ben-Menahem D. The steroidogenic effect of single-chain bovine LH analogs in cultured bovine follicular cells. Mol Cell Endocrinol 2006; 252:136-41. [PMID: 16644100 DOI: 10.1016/j.mce.2006.03.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Single-chain gonadotropin analogs had been constructed for the purpose of structure-function studies and analog design. Incorporation of a spacer derived from the carboxyl terminal peptide (CTP) of the choriogonadotropin (CG) beta subunit between the tethered subunit domains of the human gonadotropins is beneficial for the secretion of the single-chain variants without compromising biocactivity. Although the CGbeta subunit containing the CTP domain is expressed only in primates and equids, a CTP-like sequence exists in the untranslated region of the LHbeta gene of several mammalian species, including the bovine species. The CTP encrypted in the bovine LHbeta DNA (designated as 'boCTP') and the CTP derived from the human CGbeta subunit (denoted as 'huCTP') served as a linker sequence in the design of bovine single-chain luteinizing hormone (LH) analogs. The purpose of the present study was to evaluate steroidogenesis in cultured bovine theca cells following stimulation with these single-chain analogs. The concentration of the LHbetaboCTPalpha and LHbetahuCTPalpha analogs in the conditioned media of the expressing CHO cells was three- to six-fold higher than that of the "linkerless" LHbetaalpha and LHbeta111alpha variants. The four analogs induced androstenedione and progesterone secretion from the primary theca cells in a dose-dependent manner, but differences in the steroidogenic response were observed. The LHbetaboCTPalpha analog (10 ng/ml) effectively induced androstenedione and progesterone secretion over unstimulated levels (4.0- and 4.4-fold increase for androstenedione and progesterone, respectively). The response to the pituitary bovine LH standard (10 ng/ml) was less pronounced for both steroids (two- to three-fold increase over basal levels). The activities of LHbetahuCTPalpha, LHbetaalpha and LHbeta111alpha were comparable and sightly reduced relative to the LHbetaboCTPalpha activity. The data suggested that LHbetaboCTPalpha was ranked as the most potent and this was even more prominent when analogs were used at a lower dose (1 ng/ml). These data suggest that the design, including the huCTP or boCTP linker, is favorable for the production of single-chain bovine LH analogs. Furthermore, spacing of the tethered subunit domains with the cryptic boCTP sequence that originated from the bovine LHbeta gene appears advantageous for the purpose of stimulating steroid production in the species-specific bioassay. Thus, an effective strategy to produce bioactive single-chain LH analogs in non-primate, non-equid species would be the mutatation of the LHbeta genes with the aim of expressing the cryptic CTP sequence as a spacer derived from the DNA of the same organism.
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Affiliation(s)
- Ruth Braw-Tal
- Institute of Animal Science, Agricultural Research Organization, The Volcani Center, Beit Dagan 50250, Israel
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10
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Jablonka-Shariff A, Kumar TR, Eklund J, Comstock A, Boime I. Single-chain, triple-domain gonadotropin analogs with disulfide bond mutations in the alpha-subunit elicit dual follitropin and lutropin activities in vivo. Mol Endocrinol 2006; 20:1437-46. [PMID: 16601070 DOI: 10.1210/me.2005-0537] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The human glycoprotein hormones chorionic gonadotropin (CG), TSH, LH, and FSH are heterodimers composed of a common alpha-subunit and a hormone-specific beta-subunit. The subunits assemble noncovalently early in the secretory pathway. LH and FSH are synthesized in the same cell (pituitary gonadotrophs), and several of the alpha-subunit sequences required for association with either beta-subunit are different. Nevertheless, no ternary complexes are observed for LH and FSH in vivo, i.e. both beta-subunits assembled with a single alpha-subunit. To address whether the alpha-subunit can interact with more than one beta-subunit simultaneously, we genetically linked the FSHbeta- and CGbeta-subunit genes to the common alpha-subunit, resulting in a single-chain protein that exhibited both activities in vitro. These studies also indicated that the bifunctional triple-domain variant (FSHbeta-CGbeta-alpha), is secreted as two distinct bioactive populations each corresponding to a single activity, and each bearing the heterodimer-like contacts. Although the data are consistent with the known secretion events of gonadotropins from the pituitary, we could not exclude the possibility whether transient intermediates are generated in vivo in which the alpha-subunit shuttles between the two beta-subunits during early stages of accumulation in the endoplasmic reticulum. Therefore, constructs were engineered that would direct the synthesis of single-chain proteins completely devoid of heterodimer-like interactions but elicit both LH and FSH actions. These triple-domain, single-chain chimeras contain the FSHbeta- and CGbeta-subunits and an alpha-subunit with cystine bond mutations (cys10-60 or cys32-84), which are known to prevent heterodimer formation. Here we show that, despite disrupting the intersubunit interactions between the alpha- and both CGbeta- and FSHbeta-subunits, these mutated analogs exhibit both activities in vivo comparable to nonmutated triple-domain single chain. Such responses occurred despite the absence of quaternary contacts due to the disrupted bonds in the alpha-subunit. Thus, gonadotropin heterodimer assembly is critical for intracellular events, e.g. hormone-specific posttranslational modifications, but when heterodimers are present in the circulation, the alpha/beta-contacts are not a prerequisite for receptor recognition.
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MESH Headings
- Animals
- Aromatase/biosynthesis
- Aromatase/genetics
- Chorionic Gonadotropin, beta Subunit, Human/chemistry
- Chorionic Gonadotropin, beta Subunit, Human/genetics
- Chorionic Gonadotropin, beta Subunit, Human/pharmacology
- Female
- Follicle Stimulating Hormone, beta Subunit/chemistry
- Follicle Stimulating Hormone, beta Subunit/genetics
- Follicle Stimulating Hormone, beta Subunit/pharmacology
- Glycoprotein Hormones, alpha Subunit/chemistry
- Glycoprotein Hormones, alpha Subunit/genetics
- Glycoprotein Hormones, alpha Subunit/pharmacology
- Gonadotropins/chemistry
- Gonadotropins/genetics
- Gonadotropins/pharmacology
- Humans
- In Vitro Techniques
- Mice
- Mutagenesis, Site-Directed
- Organ Size/drug effects
- Ovary/drug effects
- Ovary/enzymology
- Ovary/growth & development
- Protein Subunits
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Recombinant Proteins/pharmacology
- Superovulation/drug effects
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Affiliation(s)
- Albina Jablonka-Shariff
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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11
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Kumar TR. What have we learned about gonadotropin function from gonadotropin subunit and receptor knockout mice? Reproduction 2005; 130:293-302. [PMID: 16123236 DOI: 10.1530/rep.1.00660] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A number of biochemical and physiological studies elucidated the roles of pituitary and placental glycoprotein hormones. Advances in the past two decades in manipulating the mouse genome by random or site-specific mutagenesis have heralded a new dimension to our understanding of the biology of gonadotropins. It is now possible to model many human reproductive disorders involving gonadotropins/gonadotropin-signaling in the mouse. Mutant mice selectively lacking either FSH or LH or their cognate receptors have been generated. The gonadotropin ligand and the corresponding receptor knockout mice mostly phenocopy each other. Analyses with these genetic models confirmed earlier physiological studies; in addition they also revealed novel roles for gonadotropins previously unrecognized. While FSH action seems dispensable for male but not female fertility, absence of LH causes infertility in both the sexes. While Sertoli cell number and germ cell carrying capacity of the Sertoli cells in compromised in FSH mutants, both somatic and germ cell lineages are affected in the LH mutants resulting in complete male infertility. FSH mutant females demonstrate a preantral stage block in folliculogenesis and FSH alone is not sufficient to promote full folliculogenesis in the absence of LH. Pre-ovulatory stage follicles do not form and most of the follicles undergo apoptosis in the absence of LH. Many extra-gonadal phenotypes have been described for the receptor knockout mice and whether these bear any resemblances to those in patients with similar inactivating mutations in the receptors for FSH and LH remains an open question. Thus the in vivo models will continue to have a significant impact in understanding gonadotropin physiology and pathophysiology and serve as novel genetic tools to study signaling mechanisms in the gonads.
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MESH Headings
- Animals
- Female
- Follicle Stimulating Hormone, beta Subunit/genetics
- Follicle Stimulating Hormone, beta Subunit/metabolism
- Glycoprotein Hormones, alpha Subunit/genetics
- Glycoprotein Hormones, alpha Subunit/metabolism
- Gonadotropins, Pituitary/genetics
- Gonadotropins, Pituitary/metabolism
- Humans
- Infertility/metabolism
- Luteinizing Hormone, beta Subunit/genetics
- Luteinizing Hormone, beta Subunit/metabolism
- Male
- Mice
- Mice, Knockout
- Models, Animal
- Receptors, Gonadotropin/genetics
- Receptors, Gonadotropin/metabolism
- Reproduction/physiology
- Signal Transduction/physiology
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Affiliation(s)
- T Rajendra Kumar
- Department of Molecular & Integrative Physiology, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS 66160, USA.
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12
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Kumar TR. Gonadotropin gene targeting and biological implications. Endocrine 2005; 26:227-33. [PMID: 16034176 DOI: 10.1385/endo:26:3:227] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Accepted: 04/27/2005] [Indexed: 11/11/2022]
Abstract
Pituitary gonadotropins FSH and LH are heterodimeric glycoproteins consisting of a common alpha and a hormone-specific beta subunit that are non-covalently linked. These hormones orchestrate gonadal growth, differentiation, and function by regulating both steroid-ogenesis and gametogenesis. Advances in the past two decades in manipulating the mouse genome by site-specific mutagenesis have heralded a new dimension to our understanding of the biology of gonadotropins. Using these gene-targeting approaches, knockout mice lacking the hormone-specific gonadotropin subunits, and hence the functional dimeric hormones, have been generated. These individual gonadotropin-deficient mice are useful to delineate the distinct in vivo biological roles of FSH and LH. These mice also serve as valuable genetic tools to study the signaling mechanisms within the gonads and help a better understanding of some forms of human infertility.
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Affiliation(s)
- T Rajendra Kumar
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, 66160, USA.
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