1
|
Furigo IC, Suzuki MF, Oliveira JE, Ramos-Lobo AM, Teixeira PDS, Pedroso JA, de Alencar A, Zampieri TT, Buonfiglio DC, Quaresma PGF, Prada PO, Bartolini P, Soares CRJ, Donato J. Suppression of Prolactin Secretion Partially Explains the Antidiabetic Effect of Bromocriptine in ob/ob Mice. Endocrinology 2019; 160:193-204. [PMID: 30462197 DOI: 10.1210/en.2018-00629] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 11/15/2018] [Indexed: 11/19/2022]
Abstract
Previous studies have shown that bromocriptine mesylate (Bromo) lowers blood glucose levels in adults with type 2 diabetes mellitus; however, the mechanism of action of the antidiabetic effects of Bromo is unclear. As a dopamine receptor agonist, Bromo can alter brain dopamine activity affecting glucose control, but it also suppresses prolactin (Prl) secretion, and Prl levels modulate glucose homeostasis. Thus, the objective of the current study was to investigate whether Bromo improves insulin sensitivity via inhibition of Prl secretion. Male and female ob/ob animals (a mouse model of obesity and insulin resistance) were treated with Bromo and/or Prl. Bromo-treated ob/ob mice exhibited lower serum Prl concentration, improved glucose and insulin tolerance, and increased insulin sensitivity in the liver and skeletal muscle compared with vehicle-treated mice. Prl replacement in Bromo-treated mice normalized serum Prl concentration without inducing hyperprolactinemia. Importantly, Prl replacement partially reversed the improvements in glucose homeostasis caused by Bromo treatment. The effects of the Prl receptor antagonist G129R-hPrl on glucose homeostasis were also investigated. We found that central G129R-hPrl infusion increased insulin tolerance of male ob/ob mice. In summary, our findings indicate that part of Bromo effects on glucose homeostasis are associated with decrease in serum Prl levels. Because G129R-hPrl treatment also improved the insulin sensitivity of ob/ob mice, pharmacological compounds that inhibit Prl signaling may represent a promising therapeutic approach to control blood glucose levels in individuals with insulin resistance.
Collapse
Affiliation(s)
- Isadora C Furigo
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Miriam F Suzuki
- Biotechnology Center, Instituto de Pesquisas Energéticas e Nucleares, IPEN-CNEN/SP, São Paulo, SP, Brazil
| | - João E Oliveira
- Biotechnology Center, Instituto de Pesquisas Energéticas e Nucleares, IPEN-CNEN/SP, São Paulo, SP, Brazil
| | - Angela M Ramos-Lobo
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Pryscila D S Teixeira
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - João A Pedroso
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Amanda de Alencar
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Thais T Zampieri
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Daniella C Buonfiglio
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Paula G F Quaresma
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
- Department of Internal Medicine, State University of Campinas, Campinas, São Paulo, SP, Brazil
| | - Patricia O Prada
- School of Applied Sciences, State University of Campinas, Limeira, São Paulo, SP, Brazil
| | - Paolo Bartolini
- Biotechnology Center, Instituto de Pesquisas Energéticas e Nucleares, IPEN-CNEN/SP, São Paulo, SP, Brazil
| | - Carlos R J Soares
- Biotechnology Center, Instituto de Pesquisas Energéticas e Nucleares, IPEN-CNEN/SP, São Paulo, SP, Brazil
| | - Jose Donato
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| |
Collapse
|
2
|
Liu Y, Gong W, Breinholt J, Norskov-Lauritsen L, Zhang J, Ma Q, Chen J, Panina S, Guo W, Li T, Zhang J, Kong M, Liu Z, Mao J, Christensen L, Hu S, Wang L. Discovery of the improved antagonistic prolactin variants by library screening. Protein Eng Des Sel 2011; 24:855-60. [DOI: 10.1093/protein/gzr047] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
3
|
Abstract
Human prolactin (hPRL) binds two human prolactin receptor molecules, creating active heterotrimeric complexes. Receptors bind dissimilar hormone surfaces termed site 1 and site 2 in an obligate ordered process. We sought to map the functional epitopes in site 1 of hPRL. Extensive alanine mutagenesis (102 of the 199 residues) showed approximately 40% of these mutant hPRLs changed the ΔG for site 1 receptor binding. Six of these residues are within 3.5 Å of the receptor and form the site 1 functional epitopes. We identified a set of noncovalent interactions between these six residues and the receptor. We identified a second group of site 1 residues that are between 3.5 and 5 Å from the receptor where alanine mutations reduced the affinity. This second group has noncovalent interactions with other hormone residues and stabilized the topology of the functional epitopes by linking these to the body of the protein. Finally, we identified a third group of residues that are outside site 1 (>5 Å) and extend to site 2 and whose mutation to alanine significantly weakened receptor binding at site 1 of prolactin. These three groups of residues form a contiguous structural motif between sites 1 and 2 of human prolactin and may constitute structural features that functionally couple sites 1 and 2. This work identifies the residues that form the functional epitopes for site 1 of human prolactin and also identifies a set of residues that support the concept that sites 1 and 2 are functionally coupled by an allosteric mechanism.
Collapse
Affiliation(s)
- Geeta Vittal Rao
- Ohio State Biophysics Program, Ohio State University, 1925 Coffey Road, Columbus, OH 43210, USA
| | | |
Collapse
|
4
|
van Agthoven J, Zhang C, Tallet E, Raynal B, Hoos S, Baron B, England P, Goffin V, Broutin I. Structural characterization of the stem-stem dimerization interface between prolactin receptor chains complexed with the natural hormone. J Mol Biol 2010; 404:112-26. [PMID: 20875426 DOI: 10.1016/j.jmb.2010.09.036] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Revised: 09/15/2010] [Accepted: 09/16/2010] [Indexed: 11/18/2022]
Abstract
The most promising approach to targeting the tumor-growth-promoting actions of prolactin (PRL) mediated by its autocrine/paracrine pathway has been the development of specific PRL receptor (PRLR) antagonists. However, the optimization of such antagonists requires a thorough understanding of the activation mechanism of PRLR. We have thus conducted a systematic X-ray crystallographic study in order to visualize the successive steps of PRLR activation by PRL. We report here the structure at 3.35 Å resolution of the 1:2 complex between natural PRL and two PRLR chains (PRLR1 and PRLR2), corresponding to the final activated state of PRLR. Further than our previously published structure involving an affinity-matured PRL variant, this structure allowed to visualize for the first time the loop L5 spanning PRLR2 residues Thr133-Phe140, revealing its central implication for the three intermolecular interfaces of the complex. We equally succeeded in obtaining a comprehensive picture of the PRLR-PRLR dimerization interface, also called stem-stem interface. Site-directed mutagenesis was conducted to probe the energetic importance of stem-stem contacts highlighted by the structure. Surprisingly, in spite of significant structural differences between the PRL/PRLR(2) complex and the 1:2 growth hormone/growth hormone receptor complex, our mutational data suggest that hot-spot residues that stabilize the receptor dimerization interface are equivalent in the two complexes. This study provides a new overall picture of the structural features of PRLR involved in stabilizing its complex with PRL.
Collapse
Affiliation(s)
- Jan van Agthoven
- CNRS UMR 8015, Laboratoire de cristallographie et RMN biologiques, F-75006 Paris, France
| | | | | | | | | | | | | | | | | |
Collapse
|
5
|
Broutin I, Jomain JB, Tallet E, van Agthoven J, Raynal B, Hoos S, Kragelund BB, Kelly PA, Ducruix A, England P, Goffin V. Crystal structure of an affinity-matured prolactin complexed to its dimerized receptor reveals the topology of hormone binding site 2. J Biol Chem 2010; 285:8422-33. [PMID: 20053995 PMCID: PMC2832991 DOI: 10.1074/jbc.m109.089128] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Revised: 12/21/2009] [Indexed: 11/06/2022] Open
Abstract
We report the first crystal structure of a 1:2 hormone.receptor complex that involves prolactin (PRL) as the ligand, at 3.8-A resolution. Stable ternary complexes were obtained by generating affinity-matured PRL variants harboring an N-terminal tail from ovine placental lactogen, a closely related PRL receptor (PRLR) ligand. This structure allows one to draw up an exhaustive inventory of the residues involved at the PRL.PRLR site 2 interface, consistent with all previously reported site-directed mutagenesis data. We propose, with this description, an interaction model involving three structural components of PRL site 2 ("three-pin plug"): the conserved glycine 129 of helix alpha3, the hydrogen bond network involving surrounding residues (glycine cavity), and the N terminus. The model provides a molecular basis for the properties of the different PRL analogs designed to date, including PRLR antagonists. Finally, comparison of our 1:2 PRL.PRLR(2) structure with those of free PRL and its 1:1 complex indicates that the structure of PRL undergoes significant changes when binding the first, but not the second receptor. This suggests that the second PRLR moiety adapts to the 1:1 complex rather than the opposite. In conclusion, this structure will be a useful guiding tool for further investigations of the molecular mechanisms involved in PRLR dimerization and activation, as well as for the optimization of PRLR antagonists, an emerging class of compounds with high therapeutic potential against breast and prostate cancer.
Collapse
Affiliation(s)
- Isabelle Broutin
- From the Laboratoire de Cristallographie et RMN Biologiques, CNRS, UMR 8015, Université Paris Descartes, 75006 Paris, France
| | - Jean-Baptiste Jomain
- INSERM, U845, Centre de Recherche “Croissance et Signalisation,” Equipe “PRL/GH Pathophysiology,” Paris F-75015, France
- the Université Paris Descartes, Faculté de Médecine Site Necker, Paris F-75015, France
| | - Estelle Tallet
- INSERM, U845, Centre de Recherche “Croissance et Signalisation,” Equipe “PRL/GH Pathophysiology,” Paris F-75015, France
- the Université Paris Descartes, Faculté de Médecine Site Necker, Paris F-75015, France
| | - Jan van Agthoven
- From the Laboratoire de Cristallographie et RMN Biologiques, CNRS, UMR 8015, Université Paris Descartes, 75006 Paris, France
| | - Bertrand Raynal
- the Institut Pasteur, Plateforme de Biophysique des Macromolécules et de leurs Interactions, Département de Biologie Structurale et Chimie, Paris F-75015, France
- the CNRS URA 2185, Paris F-75015, France, and
| | - Sylviane Hoos
- the Institut Pasteur, Plateforme de Biophysique des Macromolécules et de leurs Interactions, Département de Biologie Structurale et Chimie, Paris F-75015, France
- the CNRS URA 2185, Paris F-75015, France, and
| | - Birthe B. Kragelund
- the Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Paul A. Kelly
- INSERM, U845, Centre de Recherche “Croissance et Signalisation,” Equipe “PRL/GH Pathophysiology,” Paris F-75015, France
- the Université Paris Descartes, Faculté de Médecine Site Necker, Paris F-75015, France
| | - Arnaud Ducruix
- From the Laboratoire de Cristallographie et RMN Biologiques, CNRS, UMR 8015, Université Paris Descartes, 75006 Paris, France
| | - Patrick England
- the Institut Pasteur, Plateforme de Biophysique des Macromolécules et de leurs Interactions, Département de Biologie Structurale et Chimie, Paris F-75015, France
- the CNRS URA 2185, Paris F-75015, France, and
| | - Vincent Goffin
- INSERM, U845, Centre de Recherche “Croissance et Signalisation,” Equipe “PRL/GH Pathophysiology,” Paris F-75015, France
- the Université Paris Descartes, Faculté de Médecine Site Necker, Paris F-75015, France
| |
Collapse
|