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Endocrine Abstracts (2020) 70 AEP849 | DOI: 10.1530/endoabs.70.AEP849

ECE2020 Audio ePoster Presentations Reproductive and Developmental Endocrinology (79 abstracts)

Aminoacidic residues discriminating human choriogonadotropin (hCG) and luteinizing hormone (LH) binding to the human receptor (LHCGR)

Clara Lazzaretti 1,2 , Valentina Secco 1 , Elia Paradiso 1,2 , Samantha Sperduti 1,3 , Claudia Rutz 4 , Annika Kreuchwig 4 , Gerd Krause 4 , Manuela Simoni 1,3,5,6 & Livio Casarini 1,3

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1University of Modena and Reggio Emilia, Unit of Endocrinology, Department of Biomedical, Metabolic and Neural Sciences, Baggiovara, Italy; 2University of Modena and Reggio Emilia, International PhD School in Clinical and Experimental Medicine (CEM), Modena, Italy; 3University of Modena and Reggio Emilia, Center for Genomic Research, Modena, Italy; 4Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany; 5Azienda Ospedaliero-Universitaria di Modena, Department of Medical Specialties, Baggiovara, Italy; 6Centre Inra -Val De Loire, Nouzilly, France

The human luteinizing hormone (LH)/choriogonadotropin (hCG) receptor (LHCGR) discriminates its two hormone ligands. LHCGR differs to the murine receptor (Lhr) in aminoacid residues potentially involved in qualitative discerning of LH and hCG, the latter absent in rodents. We aim to identify LHCGR residues involved in hCG/LH discrimination, indicating evolutionary determinants of human LH/hCG endocrine system. After comparing the LHCGR and Lhr sequences, we developed eight LHCGR cDNAs carrying ‘murinizing’ mutations (R247T; T48R; S149F; I83S; A57T; E270V; N35D and V37A; K225S and T226I) assumed to be interacting specifically with LH, hCG or both. HEK293 cells expressing a mutant or the wild-type receptor were treated by pM-µM LH or hCG concentrations and the kinetics of cAMP and pERK1/2 activation was analysed by BRET. A Lhr-like response was obtained in cells expressing LHCGR carrying the A57T mutation as hCG is more potent than LH in inducing both cAMP (LH EC50 = 0.7 ± 0.2 nM vs hCG EC50 = 0.1 ± 0.03 nM; Mann-Whitney’s U-test; P < 0.05; n = 4; means ± s.e.m.) and kinetics of pERK 1/2 activation (Kruskal-Wallis test; P < 0.05; n = 8). The E270V mutation located in the LHCGR hinge region decreased of 2.5 times the LH, but not hCG potency in inducing cAMP production than the wild-type (LH EC50 = 2.8 ± 1.4 nM vs LH EC50wild-type = 1.1 ± 0.3 nM; hCG EC50 = 0.2 ± 0.04 nM vs hCG EC50wild-type = 0.15 ± 0.03 nM; n = 4; means ± s.e.m.), suggesting this extracellular portion of the receptor is involved in LH-specific recognition. LHCGRs carrying K225S, T226I or R247T mutations mediate similar cAMP (LH EC50 = 0.6 ± 0.2 nM vs hCG EC50 = 0.11 ± 0.1 nM and LH EC50 = 5.6 ± 0.4 nM vshCG EC50 = 0.4 ± 0.02 nM; Mann-Whitney’s U-test;P > 0.05; n = 4) and pERK1/2 response to LH and hCG (Kruskal-Wallis test; P > 0.05; n = 8). Via ‘murinization’ of LHCGR, we identified key aminoacids falling within the extracellular region of the receptor interacting with the hormone L2-β loop, which might be crucial for discriminating the two human gonadotropin ligands. We found human-specific determinants of the LH/hCG system evolution.

Volume 70

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22nd European Congress of Endocrinology

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05 Sep 2020 - 09 Sep 2020

European Society of Endocrinology 

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Aminoacidic residues discriminating human choriogonadotropin (hCG) and luteinizing hormone (LH) binding to the human receptor (LHCGR) (<1 min ago)

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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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