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Ma H, Cui Z, Guo X, Zhao Q, Zhang Y, Guan Y, Yang P, Zhu H, Wang S, Zhang X, Zhang Y, Pan HL, Ma H. Corticotropin-releasing factor potentiates glutamatergic input and excitability of presympathetic neurons in the hypothalamus in spontaneously hypertensive rats. Neuropharmacology 2023; 230:109506. [PMID: 36924924 DOI: 10.1016/j.neuropharm.2023.109506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 02/28/2023] [Accepted: 03/10/2023] [Indexed: 03/15/2023]
Abstract
Hyperactivity of presympathetic neurons in the hypothalamic paraventricular nucleus (PVN) plays a key role in generating excess sympathetic output in hypertension. However, the mechanisms driving hyperactivity of PVN presympathetic neurons in hypertension are unclear. In this study, we determined the role of corticotropin-releasing factor (CRF) in the PVN in augmented glutamatergic input, neuronal excitability and sympathetic outflow in hypertension. The number of CRF or c-Fos immunoreactive neurons and CRF/c-Fos double-labeled neurons in the PVN was significantly greater in spontaneously hypertensive rats (SHRs) than in normotensive Wistar-Kyoto (WKY) rats. Blocking glutamatergic input reduced the CRF-potentiated excitability of spinally projecting PVN neurons. Furthermore, CRF knockdown via Crispr/Cas9 in the PVN decreased the frequencies of spontaneous firing and miniature excitatory postsynaptic currents (mEPSCs) in spinally projecting PVN neurons in SHRs. In addition, the mRNA and protein levels of CRFR1, but not CRFR2, in the PVN were significantly higher in SHRs than in WKY rats. Blocking CRFR1 with NBI-35965, but not blocking CRFR2 with Antisauvagine-30, reduced the frequencies of spontaneous firing and mEPSCs of spinally projecting PVN neurons in SHRs. Also, microinjection of NBI-35965 into the PVN significantly reduced arterial blood pressure (ABP) and renal sympathetic nerve activity (RSNA) in anesthetized SHRs, but not in WKY rats. However, microinjection of Antisauvagine-30 into the PVN had no effect on ABP or RSNA in WKY rats and SHRs. Our findings suggest that endogenous CRF in the PVN potentiates glutamatergic input and firing activity of PVN presympathetic neurons via CRFR1, resulting in augmented sympathetic outflow in hypertension.
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Affiliation(s)
- Hongyu Ma
- Department of Physiology, Hebei Medical University, Shijiazhuang, 050017, Hebei, China
| | - Ziye Cui
- Department of Physiology, Hebei Medical University, Shijiazhuang, 050017, Hebei, China
| | - Xinqi Guo
- Department of Physiology, Hebei Medical University, Shijiazhuang, 050017, Hebei, China
| | - Qiyue Zhao
- Department of Physiology, Hebei Medical University, Shijiazhuang, 050017, Hebei, China
| | - Ying Zhang
- Department of Physiology, Hebei Medical University, Shijiazhuang, 050017, Hebei, China
| | - Yue Guan
- Department of Physiology, Hebei Medical University, Shijiazhuang, 050017, Hebei, China; Key Laboratory of Neurophysiology of Hebei Province, Shijiazhuang, 050017, Hebei, China
| | - Peiyun Yang
- Department of Physiology, Hebei Medical University, Shijiazhuang, 050017, Hebei, China
| | - Huaibing Zhu
- Department of Physiology, Hebei Medical University, Shijiazhuang, 050017, Hebei, China
| | - Sheng Wang
- Department of Physiology, Hebei Medical University, Shijiazhuang, 050017, Hebei, China; Key Laboratory of Neurophysiology of Hebei Province, Shijiazhuang, 050017, Hebei, China
| | - Xiangjian Zhang
- The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Hebei Medical University, Shijiazhuang, 050017, China
| | - Yi Zhang
- Department of Physiology, Hebei Medical University, Shijiazhuang, 050017, Hebei, China; Hebei Collaborative Innovation Center for Cardio-cerebrovascular Disease, Shijiazhuang, China
| | - Hui-Lin Pan
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Huijie Ma
- Department of Physiology, Hebei Medical University, Shijiazhuang, 050017, Hebei, China; Key Laboratory of Neurophysiology of Hebei Province, Shijiazhuang, 050017, Hebei, China; The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Hebei Medical University, Shijiazhuang, 050017, China; Hebei Collaborative Innovation Center for Cardio-cerebrovascular Disease, Shijiazhuang, China.
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Kasai T, Suga H, Sakakibara M, Ozone C, Matsumoto R, Kano M, Mitsumoto K, Ogawa K, Kodani Y, Nagasaki H, Inoshita N, Sugiyama M, Onoue T, Tsunekawa T, Ito Y, Takagi H, Hagiwara D, Iwama S, Goto M, Banno R, Takahashi J, Arima H. Hypothalamic Contribution to Pituitary Functions Is Recapitulated In Vitro Using 3D-Cultured Human iPS Cells. Cell Rep 2021; 30:18-24.e5. [PMID: 31914385 DOI: 10.1016/j.celrep.2019.12.009] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 08/03/2019] [Accepted: 12/03/2019] [Indexed: 10/25/2022] Open
Abstract
The pituitary is a major hormone center that secretes systemic hormones responding to hypothalamus-derived-releasing hormones. Previously, we reported the independent pituitary induction and hypothalamic differentiation of human embryonic stem cells (ESCs). Here, a functional hypothalamic-pituitary unit is generated using human induced pluripotent stem (iPS) cells in vitro. The adrenocorticotropic hormone (ACTH) secretion capacity of the induced pituitary reached a comparable level to that of adult mouse pituitary because of the simultaneous maturation with hypothalamic neurons within the same aggregates. Corticotropin-releasing hormone (CRH) from the hypothalamic area regulates ACTH cells similarly to our hypothalamic-pituitary axis. Our induced hypothalamic-pituitary units respond to environmental hypoglycemic condition in vitro, which mimics a life-threatening situation in vivo, through the CRH-ACTH pathway, and succeed in increasing ACTH secretion. Thus, we generated powerful hybrid organoids by recapitulating hypothalamic-pituitary development, showing autonomous maturation on the basis of interactions between developing tissues.
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Affiliation(s)
- Takatoshi Kasai
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Hidetaka Suga
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan.
| | - Mayu Sakakibara
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Chikafumi Ozone
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Ryusaku Matsumoto
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Mayuko Kano
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Kazuki Mitsumoto
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Koichiro Ogawa
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Yu Kodani
- Department of Physiology, Fujita Health University, Toyoake 470-1192, Japan
| | - Hiroshi Nagasaki
- Department of Physiology, Fujita Health University, Toyoake 470-1192, Japan
| | - Naoko Inoshita
- Department of Diagnostic Pathology, Toranomon Hospital, Tokyo 105-8470, Japan
| | - Mariko Sugiyama
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Takeshi Onoue
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Taku Tsunekawa
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Yoshihiro Ito
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Hiroshi Takagi
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Daisuke Hagiwara
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Shintaro Iwama
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Motomitsu Goto
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Ryoichi Banno
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Jun Takahashi
- Department of Clinical Application, Center for iPS Cell Research and Application, Kyoto University, Kyoto 606-8507, Japan
| | - Hiroshi Arima
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
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Discovery of a stable tripeptide targeting the N-domain of CRF1 receptor. Amino Acids 2020; 52:1337-1351. [PMID: 32996057 DOI: 10.1007/s00726-020-02895-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 09/19/2020] [Indexed: 10/23/2022]
Abstract
The corticotropin-releasing factor (CRF) and its CRF1 receptor (CRF1R) play a central role in the maintenance of homeostasis. Malfunctioning of the CRF/CRF1R unit is associated with several disorders, such as anxiety and depression. Non-peptide CRF1R-selective antagonists have been shown to exert anxiolytic and antidepressant effects on experimental animals. However, none of them is in clinical use today because of several side effects, thus demonstrating the need for the development of other more suitable CRF1R antagonists. In an effort to develop novel CRF1R antagonists we designed, synthesized and chemically characterized two tripeptide analogues of CRF, namely (R)-LMI and (S)-LMI, having their Leu either in R (or D) or in S (or L) configuration, respectively. Their design was based on the crystal structure of the N-extracellular domain (N-domain) of CRF1R/CRF complex, using a relevant array of computational methods. Experimental evaluation of the stability of synthetic peptides in human plasma has revealed that (R)-LMI is proteolytically more stable than (S)-LMI. Based on this finding, (R)-LMI was selected for pharmacological characterization. We have found that (R)-LMI is a CRF antagonist, inhibiting (1) the CRF-stimulated accumulation of cAMP in HEK 293 cells expressing the CRF1R, (2) the production of interleukins by adipocytes and (3) the proliferation rate of RAW 264.7 cells. (R)-LMI likely blocked agonist actions by interacting with the N-domain of CRF1R as suggested by data using a constitutively active chimera of CRF1R. We propose that (R)-LMI can be used as an optimal lead compound in the rational design of novel CRF antagonists.
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Sakellaris S, Matsoukas MT, Karageorgos V, Poulaki S, Kuppast B, Margioris A, Venihaki M, Fahmy H, Liapakis G. Selective antagonism of CRF1 receptor by a substituted pyrimidine. Hormones (Athens) 2019; 18:215-221. [PMID: 30980254 DOI: 10.1007/s42000-019-00105-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Accepted: 03/20/2019] [Indexed: 01/13/2023]
Abstract
The corticotrophin-releasing factor (CRF) and its type 1 receptor (CRF1R) regulate the hypothalamic-pituitary-adrenal axis, as well as other systems, thus playing a crucial role in the maintenance of homeostasis. Non-peptide CRF1R-selective antagonists exert therapeutic effects on experimental animals with abnormal regulation of their homeostatic mechanisms. However, none of them is as yet in clinical use. In an effort to develop novel small non-peptide CRF1R-selective antagonists, we have synthesized a series of substituted pyrimidines described in a previous study. These small molecules bind to CRF1R, with analog 3 having the highest affinity. Characteristic structural features of analog 3 are a N,N-bis(methoxyethyl)amino group at position 6 and a methyl in the alkythiol group at position 5. Based on the binding profile of analog 3, we selected it in the present study for further pharmacological characterization. The results of this study suggest that analog 3 is a potent CRF1R-selective antagonist, blocking the ability of sauvagine, a CRF-related peptide, to stimulate cAMP accumulation in HEK 293 cells via activation of CRF1R, but not via CRF2R. Moreover, analog 3 blocked sauvagine to stimulate the proliferation of macrophages, further supporting its antagonistic properties. We have also constructed molecular models of CRF1R to examine the interactions of this receptor with analog 3 and antalarmin, a prototype CRF1R-selective non-peptide antagonist, which lacks the characteristic structural features of analog 3. Our data facilitate the design of novel non-peptide CRF1R antagonists for clinical use.
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Affiliation(s)
- Stelios Sakellaris
- Department of Pharmacology, School of Medicine, University of Crete, Voutes, Heraklion, 71003, Crete, Greece
| | | | - Vlasios Karageorgos
- Department of Pharmacology, School of Medicine, University of Crete, Voutes, Heraklion, 71003, Crete, Greece
| | - Smaragda Poulaki
- Department of Clinical Chemistry, School of Medicine, University of Crete, Voutes, Heraklion, 71003, Crete, Greece
| | - Bhimanna Kuppast
- Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, SD, 57007, USA
| | - Andrew Margioris
- Department of Clinical Chemistry, School of Medicine, University of Crete, Voutes, Heraklion, 71003, Crete, Greece
| | - Maria Venihaki
- Department of Clinical Chemistry, School of Medicine, University of Crete, Voutes, Heraklion, 71003, Crete, Greece
| | - Hesham Fahmy
- Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, SD, 57007, USA
| | - George Liapakis
- Department of Pharmacology, School of Medicine, University of Crete, Voutes, Heraklion, 71003, Crete, Greece.
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Deussing JM, Chen A. The Corticotropin-Releasing Factor Family: Physiology of the Stress Response. Physiol Rev 2018; 98:2225-2286. [DOI: 10.1152/physrev.00042.2017] [Citation(s) in RCA: 127] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The physiological stress response is responsible for the maintenance of homeostasis in the presence of real or perceived challenges. In this function, the brain activates adaptive responses that involve numerous neural circuits and effector molecules to adapt to the current and future demands. A maladaptive stress response has been linked to the etiology of a variety of disorders, such as anxiety and mood disorders, eating disorders, and the metabolic syndrome. The neuropeptide corticotropin-releasing factor (CRF) and its relatives, the urocortins 1–3, in concert with their receptors (CRFR1, CRFR2), have emerged as central components of the physiological stress response. This central peptidergic system impinges on a broad spectrum of physiological processes that are the basis for successful adaptation and concomitantly integrate autonomic, neuroendocrine, and behavioral stress responses. This review focuses on the physiology of CRF-related peptides and their cognate receptors with the aim of providing a comprehensive up-to-date overview of the field. We describe the major molecular features covering aspects of gene expression and regulation, structural properties, and molecular interactions, as well as mechanisms of signal transduction and their surveillance. In addition, we discuss the large body of published experimental studies focusing on state-of-the-art genetic approaches with high temporal and spatial precision, which collectively aimed to dissect the contribution of CRF-related ligands and receptors to different levels of the stress response. We discuss the controversies in the field and unravel knowledge gaps that might pave the way for future research directions and open up novel opportunities for therapeutic intervention.
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Affiliation(s)
- Jan M. Deussing
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany; and Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Alon Chen
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany; and Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
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6
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Huang J, Tufan T, Deng M, Wright G, Zhu MY. Corticotropin releasing factor up-regulates the expression and function of norepinephrine transporter in SK-N-BE (2) M17 cells. J Neurochem 2015. [PMID: 26212818 DOI: 10.1111/jnc.13268] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Corticotropin releasing factor (CRF) has been implicated to act as a neurotransmitter or modulator in central nervous activation during stress. In this study, we examined the regulatory effect of CRF on the expression and function of the norepinephrine transporter (NET) in vitro. SK-N-BE (2) M17 cells were exposed to different concentrations of CRF for different periods. Results showed that exposure of cells to CRF significantly increased mRNA and protein levels of NET in a concentration- and time-dependent manner. The CRF-induced increase in NET expression was mimicked by agonists of either CRF receptor 1 or 2. Furthermore, similar CRF treatments induced a parallel increase in the uptake of [(3) H] norepinephrine. Both increased expression and function of NET caused by CRF were abolished by simultaneous administration of CRF receptor antagonists, indicating a mediation by CRF receptors. However, there was no additive effect for the combination of both receptor antagonists. Chromatin immunoprecipitation assays confirm an increased acetylation of histone H3 on the NET promoter following treatment with CRF. Taken together, this study demonstrates that CRF up-regulates the expression and function of NET in vitro. This regulation is mediated through CRF receptors and an epigenetic mechanism related to histone acetylation may be involved. This CRF-induced regulation on NET expression and function may play a role in development of stress-related depression and anxiety. This study demonstrated that corticotropin release factor (CRF) up-regulated the expression and function of norepinephrine transporter (NET) in a concentration- and time-dependent manner, through activation of CRF receptors and possible histone acetylation in NET promoter. The results indicate that their interaction may play an important role in stress-related physiological and pathological status.
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Affiliation(s)
- Jingjing Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Turan Tufan
- Departments of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, USA
| | - Maoxian Deng
- Departments of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, USA.,Jiangsu Polytechnic College of A&F, Jurong, Jiangsu, China
| | - Gary Wright
- Departments of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, USA
| | - Meng-Yang Zhu
- Departments of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, USA
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Carter PH, Dean T, Bhayana B, Khatri A, Rajur R, Gardella TJ. Actions of the small molecule ligands SW106 and AH-3960 on the type-1 parathyroid hormone receptor. Mol Endocrinol 2015; 29:307-21. [PMID: 25584411 DOI: 10.1210/me.2014-1129] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The parathyroid hormone receptor-1 (PTHR1) plays critical roles in regulating blood calcium levels and bone metabolism and is thus of interest for small-molecule ligand development. Of the few small-molecule ligands reported for the PTHR1, most are of low affinity, and none has a well-defined mechanism of action. Here, we show that SW106 and AH-3960, compounds previously identified to act as an antagonist and agonist, respectively, on the PTHR1, each bind to PTHR1-delNT, a PTHR1 construct that lacks the large amino-terminal extracellular domain used for binding endogenous PTH peptide ligands, with the same micromolar affinity with which it binds to the intact PTHR1. SW106 antagonized PTHR1-mediated cAMP signaling induced by the peptide analog, M-PTH(1-11), as well as by the native PTH(1-9) sequence, as tethered to the extracellular end of transmembrane domain (TMD) helix-1 of the receptor. SW106, however, did not function as an inverse agonist on either PTHR1-H223R or PTHR1-T410P, which have activating mutations at the cytoplasmic ends of TMD helices 2 and 6, respectively. The overall data indicate that SW106 and AH-3960 each bind to the PTHR1 TMD region and likely to within an extracellularly exposed area that is occupied by the N-terminal residues of PTH peptides. Additionally, they suggest that the inhibitory effects of SW106 are limited to the extracellular portions of the TMD region that mediate interactions with agonist ligands but do not extend to receptor-activation determinants situated more deeply in the helical bundle. The study helps to elucidate potential mechanisms of small-molecule binding at the PTHR1.
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Affiliation(s)
- Percy H Carter
- Endocrine Unit (T.D., A.K., T.J.G.), Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02492; Department of Photomedicine (B.B.), Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02492; CreaGen Biosciences, Inc (R.R.), Woburn, Massachusetts 01801; and Bristol-Myers Squibb Co (P.H.C.), Princeton, New Jersey 08543
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Lodge NJ, Li YW, Chin FT, Dischino DD, Zoghbi SS, Deskus JA, Mattson RJ, Imaizumi M, Pieschl R, Molski TF, Fujita M, Dulac H, Zaczek R, Bronson JJ, Macor JE, Innis RB, Pike VW. Synthesis and evaluation of candidate PET radioligands for corticotropin-releasing factor type-1 receptors. Nucl Med Biol 2014; 41:524-35. [PMID: 24793011 DOI: 10.1016/j.nucmedbio.2014.03.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 03/18/2014] [Accepted: 03/20/2014] [Indexed: 02/02/2023]
Abstract
INTRODUCTION A radioligand for measuring the density of corticotropin-releasing factor subtype-1 receptors (CRF1 receptors) in living animal and human brain with positron emission tomography (PET) would be a useful tool for neuropsychiatric investigations and the development of drugs intended to interact with this target. This study was aimed at discovery of such a radioligand from a group of CRF1 receptor ligands based on a core 3-(phenylamino)-pyrazin-2(1H)-one scaffold. METHODS CRF1 receptor ligands were selected for development as possible PET radioligands based on their binding potency at CRF1 receptors (displacement of [(125)I]CRF from rat cortical membranes), measured lipophilicity, autoradiographic binding profile in rat and rhesus monkey brain sections, rat biodistribution, and suitability for radiolabeling with carbon-11 or fluorine-18. Two identified candidates (BMS-721313 and BMS-732098) were labeled with fluorine-18. A third candidate (BMS-709460) was labeled with carbon-11 and all three radioligands were evaluated in PET experiments in rhesus monkey. CRF1 receptor density (Bmax) was assessed in rhesus brain cortical and cerebellum membranes with the CRF1 receptor ligand, [(3)H]BMS-728300. RESULTS The three ligands selected for development showed high binding affinity (IC50 values, 0.3-8nM) at CRF1 receptors and moderate lipophilicity (LogD, 2.8-4.4). [(3)H]BMS-728300 and the two (18)F-labeled ligands showed region-specific binding in rat and rhesus monkey brain autoradiography, namely higher binding density in the frontal and limbic cortex, and cerebellum than in thalamus and brainstem. CRF1 receptor Bmax in rhesus brain was found to be 50-120 fmol/mg protein across cortical regions and cerebellum. PET experiments in rhesus monkey showed that the radioligands [(18)F]BMS-721313, [(18)F]BMS-732098 and [(11)C]BMS-709460 gave acceptably high brain radioactivity uptake but no indication of the specific binding as seen in vitro. CONCLUSIONS Candidate CRF1 receptor PET radioligands were identified but none proved to be effective for imaging monkey brain CRF1 receptors. Higher affinity radioligands are likely required for successful PET imaging of CRF1 receptors.
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Affiliation(s)
- Nicholas J Lodge
- Department of Neuroscience Biology, Bristol-Myers Squibb, 5 Research Parkway, Wallingford, CT 06492-7660, USA
| | - Yu-Wen Li
- Department of Neuroscience Biology, Bristol-Myers Squibb, 5 Research Parkway, Wallingford, CT 06492-7660, USA
| | - Frederick T Chin
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Rm. B3 C346A, 10 Center Drive, Bethesda, MD 20892, USA; Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, CA 94305-5484, USA
| | - Douglas D Dischino
- Department of Radiochemistry, Bristol-Myers Squibb, 5 Research Parkway, Wallingford, CT 06492-7660, USA
| | - Sami S Zoghbi
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Rm. B3 C346A, 10 Center Drive, Bethesda, MD 20892, USA
| | - Jeffrey A Deskus
- Department of Neuroscience Chemistry, Bristol-Myers Squibb, 5 Research Parkway, Wallingford, CT 06492-7660, USA
| | - Ronald J Mattson
- Department of Neuroscience Chemistry, Bristol-Myers Squibb, 5 Research Parkway, Wallingford, CT 06492-7660, USA
| | - Masao Imaizumi
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Rm. B3 C346A, 10 Center Drive, Bethesda, MD 20892, USA
| | - Rick Pieschl
- Department of Neuroscience Biology, Bristol-Myers Squibb, 5 Research Parkway, Wallingford, CT 06492-7660, USA
| | - Thaddeus F Molski
- Department of Neuroscience Biology, Bristol-Myers Squibb, 5 Research Parkway, Wallingford, CT 06492-7660, USA
| | - Masahiro Fujita
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Rm. B3 C346A, 10 Center Drive, Bethesda, MD 20892, USA
| | - Heidi Dulac
- Department of Veterinary Sciences, Bristol-Myers Squibb, 5 Research Parkway, Wallingford, CT 06492-7660, USA
| | - Robert Zaczek
- Department of Neuroscience Biology, Bristol-Myers Squibb, 5 Research Parkway, Wallingford, CT 06492-7660, USA
| | - Joanne J Bronson
- Department of Neuroscience Chemistry, Bristol-Myers Squibb, 5 Research Parkway, Wallingford, CT 06492-7660, USA
| | - John E Macor
- Department of Neuroscience Chemistry, Bristol-Myers Squibb, 5 Research Parkway, Wallingford, CT 06492-7660, USA
| | - Robert B Innis
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Rm. B3 C346A, 10 Center Drive, Bethesda, MD 20892, USA
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Rm. B3 C346A, 10 Center Drive, Bethesda, MD 20892, USA
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9
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Ji G, Fu Y, Adwanikar H, Neugebauer V. Non-pain-related CRF1 activation in the amygdala facilitates synaptic transmission and pain responses. Mol Pain 2013; 9:2. [PMID: 23410057 PMCID: PMC3583817 DOI: 10.1186/1744-8069-9-2] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Accepted: 02/13/2013] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Corticotropin-releasing factor (CRF) plays an important role in affective states and disorders. CRF is not only a "stress hormone" but also a neuromodulator outside the hypothalamic-pituitary-adrenocortical (HPA) axis. The amygdala, a brain center for emotions, is a major site of extrahypothalamic expression of CRF and its G-protein-coupled receptors. Our previous studies showed that endogenous activation of CRF1 receptors in an arthritis pain model contributes to amygdala hyperactivity and pain-related behaviors. Here we examined the synaptic and behavioral effects of CRF in the amygdala of normal animals in the absence of tissue injury or disease. RESULTS Whole-cell patch-clamp recordings of neurons in the latero-capsular division of the central nucleus of the amygdala (CeLC) in brain slices from normal rats showed that CRF (0.1-10 nM) increased excitatory postsynaptic currents (EPSCs) at the "nociceptive" parabrachio-amygdaloid (PB-CeLC) synapse and also increased neuronal output. Synaptic facilitation involved a postsynaptic action and was blocked by an antagonist for CRF1 (NBI27914, 1 μM) but not CRF2 (astressin-2B, 1 μM) and by an inhibitor of PKA (KT5720, 1 μM) but not PKC (GF109203X, 1 μM). CRF increased a latent NMDA receptor-mediated EPSC, and this effect also required CRF1 and PKA but not CRF2 and PKC. Stereotaxic administration of CRF (10 μM, concentration in microdialysis probe) into the CeLC by microdialysis in awake rats increased audible and ultrasonic vocalizations and decreased hindlimb withdrawal thresholds. Behavioral effects of CRF were blocked by a NBI27914 (100 μM) and KT5720 (100 μM) but not GF109203x (100 μM). CRF effects persisted when HPA axis function was suppressed by pretreatment with dexamethasone (50 μg/kg, subcutaneously). CONCLUSIONS Non-pain-related activation of CRF1 receptors in the amygdala can trigger pain-responses in normal animals through a mechanism that involves PKA-dependent synaptic facilitation in CeLC neurons independent of HPA axis function. The results suggest that conditions of increased amygdala CRF levels can contribute to pain in the absence of tissue pathology or disease state.
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Affiliation(s)
- Guangchen Ji
- Department of Neuroscience & Cell Biology, The University of Texas Medical Branch, 301 University Blvd, Galveston, Texas, 77555-1069, USA
| | - Yu Fu
- Department of Neuroscience & Cell Biology, The University of Texas Medical Branch, 301 University Blvd, Galveston, Texas, 77555-1069, USA
| | - Hita Adwanikar
- Department of Neuroscience & Cell Biology, The University of Texas Medical Branch, 301 University Blvd, Galveston, Texas, 77555-1069, USA
| | - Volker Neugebauer
- Department of Neuroscience & Cell Biology, The University of Texas Medical Branch, 301 University Blvd, Galveston, Texas, 77555-1069, USA
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10
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Lodge NJ, Lelas S, Li YW, Molski T, Grace J, Sivarao DV, Post-Munson D, Healy F, Bronson JJ, Hartz R, Macor JE, Zaczek R. Pharmacological and behavioral characterization of the novel CRF1 antagonist BMS-763534. Neuropharmacology 2012; 67:284-93. [PMID: 23174340 DOI: 10.1016/j.neuropharm.2012.10.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 10/23/2012] [Accepted: 10/29/2012] [Indexed: 12/19/2022]
Abstract
BMS-763534 is a potent (CRF(1) IC(50) = 0.4 nM) and selective (>1000-fold selectivity vs. all other sites tested) CRF(1) receptor antagonist (pA2 = 9.47 vs. CRF(1)-mediated cAMP production in Y79 cells). BMS-763534 accelerated the dissociation of (125)I-o-CRF from rat frontal cortex membrane CRF(1) receptors consistent with a negative allosteric modulation of CRF binding. BMS-763534 produced dose-dependent increases in CRF(1) receptor occupancy and anxiolytic efficacy; lowest effective anxiolytic dose = 0.56 mg/kg, PO, which was associated with 71 ± 5% CRF(1) receptor occupancy of frontoparietal CRF(1) receptors. Sedative/ataxic effects of BMS-763534 were only observed at high dose multiples (54-179×) relative to the lowest dose required for anxiolytic efficacy. At doses of 5- to 18-fold higher than the lowest efficacious dose in the anxiety assay, BMS-763534 shared subjective effects with the benzodiazepine chlordiazepoxide. Interestingly BMS-790318, the O-demethylated metabolite of BMS-763534, showed weak affinity for the TBOB site of the GABA(A) receptor (67% inhibition at 10 μM) and augmented GABA evoked currents (EC(50) = 1.6 μM). Thus, the unanticipated signal in the drug discrimination assay may have resulted from an interaction of the metabolite BMS-790318 with the TBOB site on the GABA(A) channel where it appears to behave as an allosteric potentiator of GABA evoked currents.
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Affiliation(s)
- Nicholas J Lodge
- Department of Neuroscience Biology, Bristol-Myers Squibb, 5 Research Parkway, Wallingford, CT 06492-7660, USA.
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11
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Fleck BA, Hoare SRJ, Pick RR, Bradbury MJ, Grigoriadis DE. Binding kinetics redefine the antagonist pharmacology of the corticotropin-releasing factor type 1 receptor. J Pharmacol Exp Ther 2012; 341:518-31. [PMID: 22357972 DOI: 10.1124/jpet.111.188714] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Corticotropin-releasing factor (CRF) receptor antagonists are under preclinical and clinical investigation for stress-related disorders. In this study the impact of receptor-ligand binding kinetics on CRF₁ receptor antagonist pharmacology was investigated by measuring the association rate constant (k₁), dissociation rate constant (k₋₁), and kinetically derived affinity at 37°C. Three aspects of antagonist pharmacology were reevaluated: comparative binding activity of advanced compounds, in vivo efficacy, and structure-activity relationships. Twelve lead compounds, with little previously noted difference of affinity, varied substantially in their kinetic binding activity with a 510-fold range of kinetically derived affinity (k₋₁/k₁), 170-fold range of k₋₁, and 13-fold range of k₁. The k₋₁ values indicated previous affinity measurements were not close to equilibrium, resulting in compression of the measured affinity range. Dissociation was exceptionally slow for three ligands (k₋₁ t(1/2) of 1.6-7.2 h at 37°C). Differences of binding behavior were consistent with in vivo pharmacodynamics (suppression of adrenocorticotropin in adrenalectomized rats). Ligand concentration-effect relationships correlated with their kinetically derived affinity. Two ligands that dissociated slowly (53 and 130 min) produced prolonged suppression, whereas only transient suppression was observed with a more rapidly dissociating ligand (16 min). Investigating the structure-activity relationship indicated exceptionally low values of k₁, approaching 100,000-fold less than the diffusion-limited rate. Retrospective interpretation of medicinal chemistry indicates optimizing specific elements of chemical structure overcame kinetic barriers in the association pathway, for example, constraint of the pendant aromatic orthogonal to the ligand core. Collectively, these findings demonstrate receptor binding kinetics provide new dimensions for understanding and potentially advancing the pharmacology of CRF₁ receptor antagonists.
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Affiliation(s)
- Beth A Fleck
- Neurocrine Biosciences Inc., San Diego, California, USA
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12
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Melancon BJ, Hopkins CR, Wood MR, Emmitte KA, Niswender CM, Christopoulos A, Conn PJ, Lindsley CW. Allosteric modulation of seven transmembrane spanning receptors: theory, practice, and opportunities for central nervous system drug discovery. J Med Chem 2012; 55:1445-64. [PMID: 22148748 DOI: 10.1021/jm201139r] [Citation(s) in RCA: 180] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Bruce J Melancon
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
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13
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Jagoda EM, Lang L, McCullough K, Contoreggi C, Kim BM, Ma Y, Rice KC, Szajek LP, Eckelman WC, Kiesewetter DO. [(76) Br]BMK-152, a nonpeptide analogue, with high affinity and low nonspecific binding for the corticotropin-releasing factor type 1 receptor. Synapse 2011; 65:910-8. [PMID: 21308801 PMCID: PMC3625961 DOI: 10.1002/syn.20919] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Accepted: 01/20/2011] [Indexed: 11/07/2022]
Abstract
Corticotropin-releasing factor (CRF), a neuropeptide, regulates endocrine and autonomic responses to stress through G-protein coupled receptors, CRF(1) or CRF(2) . A PET ligand able to monitor changes in CRF(1) receptor occupancy in vivo would aid in understanding the pathophysiology of stress-related diseases as well as in the clinical development of nonpeptide antagonists with therapeutic value. We have radiolabeled the CRF(1) receptor ligand, [8-(4-bromo-2,6-dimethoxyphenyl)-2,7-dimethylpyrazolo[1,5-α][1,3,5]triazin-4-yl]-N,N-bis-(2-methoxyethyl)amine (BMK-152) (ClogP = 2.6), at both the 3 and 4 position with [(76) Br]. Using in vitro autoradiography saturation studies the 4-[(76) Br]BMK-152 exhibited high affinity binding to both rat (K(d) = 0.23 ± 0.07 nM; n = 3) and monkey frontal cortex (K(d) = 0.31 ± 0.08 nM; n = 3) consistent with CRF(1) receptor regional distribution whereas with the 3-[(76) Br]BMK-152, the K(d) s could not be determined due to high nonspecific binding. In vitro autoradiography competition studies using [(125) I]Tyr(0) -o-CRF confirmed that 3-Br-BMK-152 (K(i) = 24.4 ± 4.9 nM; n = 3) had lower affinity (70-fold) than 4-Br-BMK-152 (K(i) = 0.35 ± 0.07 nM; n = 3) in monkey frontal cortex and similiar studies using [(125) I]Sauvagine confirmed CRF(1) receptor selectivity. In vivo studies with P-glycoprotein (PGP) knockout mice (KO) and their wild-type littermates (WT) showed that the brain uptake of 3-[(76) Br]BMK/4-[(76) Br]BMK was increased less than twofold in KO versus WT indicating that 3-[(76) Br]BMK-152/4-[(76) Br]BMK was not a Pgp substrate. Rat brain uptakes of 4-[(76) Br] BMK-152 from ex vivo autoradiography studies showed regional localization consistent with known published CRF(1) receptor distribution and potential as a PET ligand for in vivo imaging of CRF(1) receptors.
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Affiliation(s)
- Elaine M Jagoda
- PET Radiochemistry Group, NIBIB, National Institutes of Health, Bethesda, Maryland 20892-1088, USA.
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14
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Wu SV, Yuan PQ, Lai J, Wong K, Chen MC, Ohning GV, Taché Y. Activation of Type 1 CRH receptor isoforms induces serotonin release from human carcinoid BON-1N cells: an enterochromaffin cell model. Endocrinology 2011; 152:126-37. [PMID: 21123435 PMCID: PMC3219048 DOI: 10.1210/en.2010-0997] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
CRH and 5-hydroxytryptamine (5-HT) are expressed in human colonic enterochromaffin (EC) cells, but their interactions at the cellular level remain largely unknown. The mechanistic and functional relationship between CRH and 5-HT systems in EC cells was investigated in a human carcinoid cloned BON cell line (BON-1N), widely used as an in vitro model of EC cell function. First, we identified multiple CRH(1) splice variants, including CRH(1a), CRH(1c), CRH(1f), and a novel form lacking exon 4, designated here as CRH(1i), in the BON-1N cells. The expression of CRH(1i) was also confirmed in human brain cortex, pituitary gland, and ileum. Immunocytochemistry and immunoblot analysis confirmed that BON-1N cells were CRH(1) and 5-HT positive. CRH, urocortin (Ucn)-1, and cortagine, a selective CRH(1) agonist, all increased intracellular cAMP, and this concentration-dependent response was inhibited by CRH(1)-selective antagonist NBI-35965. CRH and Ucn-1, but not Ucn-2, stimulated significant ERK1/2 phosphorylation. In transfected human embryonic kidney-293 cells, CRH(1i) isoforms produced a significant increase in pERK1/2 in response to CRH(1) agonists that was sensitive to NBI-35965. CRH and Ucn-1 stimulated 5-HT release that reached a maximal increase of 3.3- and 4-fold at 10(-8) m over the basal level, respectively. In addition, exposure to CRH for 24-h up-regulated tryptophan hydroxylase-1 mRNA levels in the BON-1N cells. These findings define the expression of EC cell-specific CRH(1) isoforms and activation of CRH(1)-dependent pathways leading to 5-HT release and synthesis; thus, providing functional evidence of a link exists between CRH and 5-HT systems, which have implications in stress-induced CRH(1) and 5-HT-mediated stimulation of lower intestinal function.
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Affiliation(s)
- S Vincent Wu
- CURE, Building 115, Room 217, Veterans Affairs Greater Los Angeles Healthcare System, 11301 Wilshire Boulevard, Los Angeles, California 90073, USA.
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15
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Yanamala N, Klein-Seetharaman J. Allosteric Modulation of G Protein Coupled Receptors by Cytoplasmic, Transmembrane and Extracellular Ligands. Pharmaceuticals (Basel) 2010; 3:3324-3342. [PMID: 24009470 PMCID: PMC3760430 DOI: 10.3390/ph3103324] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
G protein coupled receptors (GPCRs) bind diverse classes of ligands, and depending on the receptor, these may bind in their transmembrane or the extracellular domains, demonstrating the principal ability of GPCRs to bind ligand in either domains. Most recently, it was also observed that small molecule ligands can bind in the cytoplasmic domain, and modulate binding and response to extracellular or transmembrane ligands. Thus, all three domains in GPCRs are potential sites for allosteric ligands, and whether a ligand is allosteric or orthosteric depends on the receptor. Here, we will review the evidence supporting the presence of putative binding pockets in all three domains of GPCRs and discuss possible pathways of communication between these pockets.
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Affiliation(s)
| | - Judith Klein-Seetharaman
- To whom correspondence should be addressed; E-Mail: ; Tel.: +1 412 383 7325; Fax: +1 412 648 8998
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16
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Gordon JC, Edwards P, Elmore CS, Lazor LA, Paschetto K, Bostwick R, Sylvester M, Mauger R, Scott C, Aharony D. [¹²⁵I]YP20: a novel radioligand specific for the extracellular domain of the CRF₁ receptor. Eur J Pharmacol 2010; 649:59-63. [PMID: 20854803 DOI: 10.1016/j.ejphar.2010.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 08/12/2010] [Accepted: 09/06/2010] [Indexed: 11/25/2022]
Abstract
The peptide corticotropin-releasing factor (CRF) binds to the CRF₁ receptor via a two-domain mechanism such that the extracellular domain (ECD) of the receptor captures the CRF's C-terminus to facilitate the binding of CRF's N-terminus to the juxta-membrane or "J"-site. Known small molecule antagonists bind to the J-site while known CRF₁ receptor peptide radioligands bind to both sites. We report here the in vitro binding properties of the first radioligand that binds exclusively to the ECD of the CRF₁ receptor. This ligand, which we named [¹²⁵I]Yamada peptide 20 ([¹²⁵I]YP20), is a radiolabeled analog of a synthetic peptide first reported by Yamada et al. (2004). We confirmed its high affinity for the [¹²⁵I]CRF binding site on the hCRF₁ receptor and also found it to potently antagonize CRF-stimulated cAMP production in hCRF₁-CHO cells. Under optimized conditions, 20 pM [¹²⁵I]YP20 reproducibly bound to hCRF₁-CHO membranes with a pharmacology consistent with binding specific to the ECD of the CRF₁ receptor. Saturation binding studies revealed the presence of a high affinity site with an estimated K(d) of ≈0.9 nM. The kinetic association of 20 pM [¹²⁵I]YP20 binding best fit to a rapid component (t(1/2)=0.69 min) and a sluggish component (t(1/2)=42 min). [¹²⁵I]YP20's specific binding was rapidly reversible with dissociation kinetics also best described by two phases (t(1/2)=0.92 min and t(1/2)=11.7 min). While [¹²⁵I]YP20's binding kinetics are complex, its high affinity and pharmacological specificity indicate that it is an excellent radioligand for probing the ECD site of the CRF₁ receptor.
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Affiliation(s)
- John C Gordon
- CNS Discovery, AstraZeneca, Wilmington, Delaware 19850-5437, USA.
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17
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Gkountelias K, Papadokostaki M, Javitch JA, Liapakis G. Exploring the binding site crevice of a family B G protein-coupled receptor, the type 1 corticotropin releasing factor receptor. Mol Pharmacol 2010; 78:785-93. [PMID: 20664003 DOI: 10.1124/mol.110.065474] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Family B of G protein-coupled receptors (GPCRs) is composed of receptors that bind peptides, such as secretin, glucagon, parathyroid hormone, and corticotropin releasing factor (CRF), which play critical physiological roles. These receptors, like all GPCRs, share a common structural motif of seven membrane-spanning segments, which have been proposed to bind small ligands, such as antalarmin, a nonpeptide antagonist of the type 1 receptor for CRF (CRF(1)). This leads to the hypothesis that as for family A GPCRs, the binding sites of small ligands for family B GPCRs are on the surface of a water-accessible crevice, the binding-site crevice, which is formed by the membrane-spanning segments and extends from the extracellular surface of the receptor into the plane of the membrane. To test this hypothesis we have begun to obtain structural information about family B GPCRs, using as a prototype the CRF(1), by determining the ability of sulfhydryl-specific methanethiosulfonate derivatives, such as the methanethiosulfonate-ethylammonium (MTSEA), to react with CRF(1) and thus irreversibly inhibit (125)I-Tyr(0)-sauvagine binding. We found that MTSEA inhibited (125)I-Tyr(0)-sauvagine binding to CRF(1) and that antalarmin protected against this irreversible inhibition. To identify the susceptible cysteine(s), we mutated, one at a time, four endogenous cysteines to serine. Mutation to serine of Cys211, Cys233, or Cys364 decreased the susceptibility of sauvagine binding to irreversible inhibition by MTSEA. Thus, Cys211, Cys233, and Cys364 at the cytoplasmic ends of the third, fourth, and seventh membrane-spanning segments, respectively, are exposed in the binding site crevice of CRF(1).
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Affiliation(s)
- Kostas Gkountelias
- Department of Pharmacology, Faculty of Medicine, University of Crete, Heraklion 71003, Crete, Greece
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18
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De Amici M, Dallanoce C, Holzgrabe U, Tränkle C, Mohr K. Allosteric ligands for G protein-coupled receptors: a novel strategy with attractive therapeutic opportunities. Med Res Rev 2010; 30:463-549. [PMID: 19557759 DOI: 10.1002/med.20166] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Allosteric receptor ligands bind to a recognition site that is distinct from the binding site of the endogenous messenger molecule. As a consequence, allosteric agents may attach to receptors that are already transmitter-bound. Ternary complex formation opens an avenue to qualitatively new drug actions at G protein-coupled receptors (GPCRs), in particular receptor subtype selective potentiation of endogenous transmitter action. Consequently, suitable exploitation of allosteric recognition sites as alternative molecular targets could pave the way to a drug discovery paradigm different from those aimed at mimicking or blocking the effects of endogenous (orthosteric) receptor activators. The number of allosteric ligands reported to modulate GPCR function is steadily increasing and some have already reached routine clinical use. This review aims at introducing into this fascinating field of drug discovery and at providing an overview about the achievements that have already been made. Various case examples will be discussed in the framework of GPCR classification (family A, B, and C receptors). In addition, the behavior at muscarinic receptors of hybrid derivatives incorporating both an allosteric and an orthosteric fragment in a common molecular skeleton will be illustrated.
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Affiliation(s)
- Marco De Amici
- Department of Pharmaceutical Sciences Pietro Pratesi, University of Milan, via Mangiagalli 25, 20133 Milano, Italy.
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19
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Hoare SRJ. Allosteric modulators of class B G-protein-coupled receptors. Curr Neuropharmacol 2010; 5:168-79. [PMID: 19305799 PMCID: PMC2656815 DOI: 10.2174/157015907781695928] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Accepted: 04/05/2007] [Indexed: 11/22/2022] Open
Abstract
Class B GPCR’s are activated by peptide ligands, typically 30-40 amino acid residues, that are involved in major physiological functions such as glucose homeostasis (glucagon and glucagon-like peptide 1), calcium homeostasis and bone turnover (parathyroid hormone and calcitonin), and control of the stress axis (corticotropin-releasing factor). Peptide therapeutics have been developed targeting these receptors but development of nonpeptide ligands, enabling oral administration, has proved challenging. Allosteric modulation of these receptors provides a potential route to developing nonpeptide ligands that inhibit, activate, or potentiate activation of these receptors. Here the known mechanisms of allosteric modulators targeting Class B GPCR’s are reviewed, particularly nonpeptide antagonists of the corticotropin-releasing factor 1 receptor and allosteric enhancers of the glucagon-like peptide-1 receptor. Also discussed is the potential for antagonist ligands to operate by competitive inhibition of one of the peptide binding sites, analogous to the Charniere mechanism. These mechanisms are then used to discuss potential strategies and management of pharmacological complexity in the future development of allosteric modulators for Class B GPCR’s.
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Affiliation(s)
- Sam R J Hoare
- Department of Discovery Biology, Neurocrine Biosciences Inc., San Diego, CA 92130, USA.
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20
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Valego NK, Rose JC. A specific CRH antagonist attenuates ACTH-stimulated cortisol secretion in ovine adrenocortical cells. Reprod Sci 2010; 17:477-86. [PMID: 20220106 DOI: 10.1177/1933719110361959] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Corticotropin releasing hormone (CRH) has been detected in the adrenal gland of many species and may be involved in regulation of glucocorticoid secretion. In cultured human fetal adrenal definitive/transitional zone cells, CRH upregulates the adrenocorticotropic hormone (ACTH) receptor and steroidogenic enzymes and is blocked by the selective CRH type 1 receptor (CRH(1)) antagonist, antalarmin. Based on these findings and evidence that antalarmin infusion into sheep suppressed prepartum increases in cortisol, we hypothesized that antalarmin would influence adrenal cortisol secretion. Antalarmin strongly attenuated ACTH and forskolin (FSK)-stimulated cortisol and cyclic adenosine monophosphate (cAMP) release from cultured ovine adrenocortical cells but did not prevent ACTH binding to cells or ACTH-induced proliferation in adult cells. Corticotropin releasing hormone was minimally effective as a secretagogue but increased the cortisol response to subsequent ACTH. These results suggest that antalarmin attenuates ACTH-induced cortisol secretion from cultured ovine adrenal cortical cells at a site distal to the ACTH receptor. Although CRH may modulate the secretory response to ACTH, it is probably not a direct cortisol secretagogue in the sheep.
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Affiliation(s)
- Nancy K Valego
- Center of Research for Obstetrics and Gynecology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
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21
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Gkountelias K, Tselios T, Venihaki M, Deraos G, Lazaridis I, Rassouli O, Gravanis A, Liapakis G. Alanine scanning mutagenesis of the second extracellular loop of type 1 corticotropin-releasing factor receptor revealed residues critical for peptide binding. Mol Pharmacol 2009; 75:793-800. [PMID: 19124613 DOI: 10.1124/mol.108.052423] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Upon binding of the corticotropin-releasing factor (CRF) analog sauvagine to the type 1 CRF receptor (CRF(1)), the amino-terminal portion of the peptide has been shown to lie near Lys257 in the receptor's second extracellular loop (EL2). To test the hypothesis that EL2 residues play a role in the binding of sauvagine to CRF(1) we carried out an alanine-scanning mutagenesis study to determine the functional role of EL2 residues (Leu251 to Val266). Only the W259A, F260A, and W259A/F260A mutations reduced the binding affinity and potency of sauvagine. In contrast, these mutations did not seem to significantly alter the overall receptor conformation, in that they left unchanged the affinities of the ligands astressin and antalarmin that have been suggested to bind to different regions of CRF(1). The W259A, F260A, and W259A/F260A mutations also decreased the affinity of the endogenous ligand, CRF, implying that these residues may play a common important role in the binding of different peptides belonging to CRF family. Parallel amino acid deletions of the two peptides produced ligands with various affinities for wild-type CRF(1) compared with the W259A, F260A, and W259A/F260A mutants, supporting the interaction between the amino-terminal residues 8 to 10 of sauvagine and the corresponding region in CRF with EL2 of CRF(1). This is the first time that a specific region of CRF(1) has been implicated in detailed interactions between the receptor and the amino-terminal portion of peptides belonging to the CRF family.
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Affiliation(s)
- Kostas Gkountelias
- Department of Pharmacology, Faculty of Medicine, University of Crete, Heraklion, Crete, Greece
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Drugability of extracellular targets: discovery of small molecule drugs targeting allosteric, functional, and subunit-selective sites on GPCRs and ion channels. Neuropsychopharmacology 2009; 34:106-25. [PMID: 18800070 DOI: 10.1038/npp.2008.149] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Beginning with the discovery of the structure of deoxyribose nucleic acid in 1953, by James Watson and Francis Crick, the sequencing of the entire human genome some 50 years later, has begun to quantify the classes and types of proteins that may have relevance to human disease with the promise of rapidly identifying compounds that can modulate these proteins so as to have a beneficial and therapeutic outcome. This so called 'drugable space' involves a variety of membrane-bound proteins including the superfamily of G-protein-coupled receptors (GPCRs), ion channels, and transporters among others. The recent number of novel therapeutics targeting membrane-bound extracellular proteins that have reached the market in the past 20 years however pales in magnitude when compared, during the same timeframe, to the advancements made in the technologies available to aid in the discovery of these novel therapeutics. This review will consider select examples of extracellular drugable targets and focus on the GPCRs and ion channels highlighting the corticotropin releasing factor (CRF) type 1 and gamma-aminobutyric acid receptors, and the Ca(V)2.2 voltage-gated ion channel. These examples will elaborate current technological advancements in drug discovery and provide a prospective framework for future drug development.
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Differential mechanisms of CRF1 and CRF2 receptor functions in the amygdala in pain-related synaptic facilitation and behavior. J Neurosci 2008; 28:3861-76. [PMID: 18400885 DOI: 10.1523/jneurosci.0227-08.2008] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
A major site of extrahypothalamic expression of corticotropin-releasing factor (CRF) and its G-protein-coupled CRF1 and CRF2 receptors is the amygdala, a key player in emotions and affective disorders. Pain-related plasticity in the laterocapsular division of the central nucleus of the amygdala (CeLC) generates emotional-affective responses and anxiety-like behavior. CRF1 receptor antagonists have anxiolytic effects. Although both CRF1 and CRF2 receptors couple positively to adenylyl cyclase, they can have opposite effects, but the underlying mechanism is unknown. This study addressed CRF1 and CRF2 receptor functions and mechanisms in the amygdala in a model of arthritic pain. Using whole-cell patch-clamp recordings of CeLC neurons, we found that a selective CRF1 receptor antagonist (NBI27914 [5-chloro-4-(N-(cyclopropyl)methyl-N-propylamino)-2-methyl-6-(2,4,6-trichlorophenyl)]) amino-pyridine inhibited synaptic facilitation in brain slices from arthritic rats through a postsynaptic mechanism. Inhibition of the NMDA receptor-mediated synaptic component was occluded by a protein kinase A (PKA) inhibitor, consistent with our previous demonstration of PKA-dependent increased NMDA receptor function in arthritis pain-related plasticity. NBI27914 also decreased neuronal excitability through inhibition of highly tetraethylammonium (TEA)-sensitive ion channels that contribute to action potential repolarization and firing rate. In contrast, a CRF2 receptor antagonist (astressin-2B [cyclo(31-34) [d-Phe11,His12,C alphaMeLeu13,39, Nle17, Glu31, Lys34] Ac-Sauvagine(8-40)]) facilitated synaptic transmission through presynaptic inhibition of GABAergic transmission (disinhibition). NBI27914 inhibited arthritis pain-related behaviors (audible and ultrasonic vocalizations and hindlimb withdrawal reflexes). Astressin-2B had no significant behavioral effect. The data suggest that endogenous CRF1 receptor activation in the amygdala contributes to pain-related synaptic facilitation, increased excitability, and pain behavior through a postsynaptic mechanism involving activation of PKA and highly TEA-sensitive K(+)-currents. Presynaptic CRF2 receptor-mediated inhibition does not reach behavioral significance.
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Richardson HN, Zhao Y, Fekete ÉM, Funk CK, Wirsching P, Janda K, Zorrilla EP, Koob GF. MPZP: a novel small molecule corticotropin-releasing factor type 1 receptor (CRF1) antagonist. Pharmacol Biochem Behav 2008; 88:497-510. [PMID: 18031798 PMCID: PMC3319109 DOI: 10.1016/j.pbb.2007.10.008] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2007] [Revised: 10/13/2007] [Accepted: 10/17/2007] [Indexed: 10/22/2022]
Abstract
The extrahypothalamic stress peptide corticotropin-releasing factor (CRF) system is an important regulator of behavioral responses to stress. Dysregulation of CRF and the CRF type 1 receptor (CRF(1)) system is hypothesized to underlie many stress-related disorders. Modulation of the CRF(1) system by non-peptide antagonists currently is being explored as a therapeutic approach for anxiety disorders and alcohol dependence. Here, we describe a new, less hydrophilic (cLogP approximately 2.95), small molecule, non-peptide CRF(1) antagonist with high affinity (K(i)=4.9 nM) and specificity for CRF(1) receptors: N,N-bis(2-methoxyethyl)-3-(4-methoxy-2-methylphenyl)-2,5-dimethyl-pyrazolo[1,5-a] pyrimidin-7-amine (MPZP). The compound was systemically administered to adult male rats in two behavioral models dependent on the CRF(1) system: defensive burying (0, 5, 20 mg/kg, n=6-11 for each dose) and alcohol dependence (0, 5, 10, 20 mg/kg, n=8 for each self-administration group). Acute administration of MPZP reduced burying behavior in the defensive burying model of active anxiety-like behavior. MPZP also attenuated withdrawal-induced excessive drinking in the self-administration model of alcohol dependence without affecting nondependent alcohol drinking or water consumption. The present findings support the proposed significance of the CRF(1) system in anxiety and alcohol dependence and introduce a promising new compound for further development in the treatment of alcohol dependence and stress-related disorders.
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Affiliation(s)
- Heather N. Richardson
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, 92037 California, USA
| | - Yu Zhao
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, 92037 California, USA
| | - Éva M. Fekete
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, 92037 California, USA
- Institute of Physiology, Pécs University Medical School, 7602 Pécs, Hungary
| | - Cindy K. Funk
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, 92037 California, USA
- Institut National de la Sante et de la Recherche Medicale, France
| | - Peter Wirsching
- Department of Chemistry, The Scripps Research Institute, La Jolla, 92037 California, USA
| | - Kim Janda
- Department of Chemistry, The Scripps Research Institute, La Jolla, 92037 California, USA
| | - Eric P. Zorrilla
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, 92037 California, USA
- Harold L. Dorris Neurological Research Institute, The Scripps Research Institute, La Jolla, 92037 California, USA
| | - George F. Koob
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, 92037 California, USA
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25
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Hoare SRJ, Fleck BA, Gross RS, Crowe PD, Williams JP, Grigoriadis DE. Allosteric ligands for the corticotropin releasing factor type 1 receptor modulate conformational states involved in receptor activation. Mol Pharmacol 2008; 73:1371-80. [PMID: 18239030 DOI: 10.1124/mol.107.042978] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Allosteric modulators of G-protein-coupled receptors can regulate conformational states involved in receptor activation ( Mol Pharmacol 58: 1412-1423, 2000 ). This hypothesis was investigated for the corticotropin-releasing factor type 1 (CRF(1)) receptor using a novel series of ligands with varying allosteric effect on CRF binding (inhibition to enhancement). For the G-protein-uncoupled receptor, allosteric modulation of CRF binding was correlated with nonpeptide ligand signaling activity; inverse agonists inhibited and agonists enhanced CRF binding. These data were quantitatively consistent with a two-state equilibrium underlying the modulation of CRF binding to the G-protein-uncoupled receptor. We next investigated the allosteric effect on CRF-stimulated G-protein coupling. Ligands inhibited CRF-stimulated cAMP accumulation regardless of their effect on the G-protein-uncoupled state. The modulators reduced CRF E(max) values, suggesting that they reduced the efficacy of a CRF-bound active state to couple to G-protein. Consistent with this hypothesis, the modulators inhibited binding to a guanine nucleotide-sensitive state. Together, the results are quantitatively consistent with a model in which 1) the receptor exists in three predominant states: an inactive state, a weakly active state, and a CRF-bound fully active state; 2) allosteric inverse agonists stabilize the inactive state, and allosteric agonists stabilize the weakly active state; and 3) antagonism of CRF signaling results from destabilization of the fully active state. These findings imply that nonpeptide ligands differentially modulate conformational states involved in CRF(1) receptor activation and suggest that different conformational states can be targeted in designing nonpeptide ligands to inhibit CRF signaling.
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Affiliation(s)
- Sam R J Hoare
- Emerging Technologies Biomedical Research and Innovative Discovery Group, Neurocrine Biosciences Inc., 12790 El Camino Real, San Diego, CA 92130, USA.
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26
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Ji G, Neugebauer V. Pro- and anti-nociceptive effects of corticotropin-releasing factor (CRF) in central amygdala neurons are mediated through different receptors. J Neurophysiol 2008; 99:1201-12. [PMID: 18171711 DOI: 10.1152/jn.01148.2007] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Corticotropin-releasing factor (CRF) is not only a stress hormone but also acts as a neuromodulator outside the hypothalamic-pituitary-adrenocortical axis, playing an important role in anxiety, depression, and pain modulation. The underlying mechanisms remain to be determined. A major site of extra-hypothalamic expression of CRF and its receptors is the amygdala, a key player in affect-related disorders such as anxiety. The latero-capsular division of the central nucleus of the amygdala (CeLC) is also important for pain modulation and pain affect. This study analyzed the effects of CRF on nociceptive processing in CeLC neurons and the contribution of CRF1 and CRF2 receptors and protein kinases A and C. Extracellular single-unit recordings were made from CeLC neurons in anesthetized adult rats. All neurons responded more strongly to noxious than innocuous mechanical stimulation of the knee. Evoked responses and background activity were measured before and during administration of CRF into the CeLC by microdialysis. CRF was administered alone or together with receptor antagonists or protein kinase inhibitors. CRF (0.01-1 microM; concentrations in microdialysis probe; 15 min) facilitated the evoked responses more strongly than background activity; a higher concentration (10 microM) had inhibitory effects. Facilitation by CRF (0.1 microM) was reversed by a selective CRF1 receptor antagonist (NBI27914, 10 microM) but not a CRF2 receptor antagonist (astressin-2B, 100 microM) and by a protein kinase A (PKA) inhibitor (KT5720, 100 microM) but not a protein kinase C inhibitor (GF109203X, 100 microM). Inhibitory effects of CRF (10 microM) were reversed by astressin-2B. These data suggest that CRF has dual effects on amygdala neurons: CRF1 receptor-mediated PKA-dependent facilitation and CRF2 receptor-mediated inhibition.
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Affiliation(s)
- Guangchen Ji
- Department of Neuroscience and Cell Biology, The University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555-1069, USA
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27
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Raddatz R, Schaffhauser H, Marino MJ. Allosteric approaches to the targeting of G-protein-coupled receptors for novel drug discovery: A critical assessment. Biochem Pharmacol 2007; 74:383-91. [PMID: 17572390 DOI: 10.1016/j.bcp.2007.05.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Revised: 05/07/2007] [Accepted: 05/08/2007] [Indexed: 10/23/2022]
Abstract
In recent years, the concept of allosteric modulation of G-protein-coupled receptors (GPCRs) has matured and now represents an increasingly viable approach to drug discovery. This is evident in the fact that allosteric modulators have been reported for every class of GPCR, and several are currently in clinical trials with one drug example approved and launched. The allosteric approach has been highlighted for the potential of identifying highly selective compounds with a minimal propensity to produce adverse effect. While much has been written regarding the promises of this approach, important challenges, caveats, and pitfalls exist that are often overlooked. Therefore, a balanced overview of the field that describes both the promises and the challenges of discovering allosteric modulators of GPCRs as novel drugs is presented.
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Affiliation(s)
- Rita Raddatz
- World Wide Discovery Research, Cephalon, Inc., United States
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28
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Fekete ÉM, Zorrilla EP. Physiology, pharmacology, and therapeutic relevance of urocortins in mammals: ancient CRF paralogs. Front Neuroendocrinol 2007; 28:1-27. [PMID: 17083971 PMCID: PMC2730896 DOI: 10.1016/j.yfrne.2006.09.002] [Citation(s) in RCA: 199] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2006] [Revised: 09/05/2006] [Accepted: 09/06/2006] [Indexed: 12/13/2022]
Abstract
Urocortins, three paralogs of the stress-related peptide corticotropin-releasing factor (CRF) found in bony fish, amphibians, birds, and mammals, have unique phylogenies, pharmacologies, and tissue distributions. As a result and despite a structural family resemblance, the natural functions of urocortins and CRF in mammalian homeostatic responses differ substantially. Endogenous urocortins are neither simply counterpoints nor mimics of endogenous CRF action. In their own right, urocortins may be clinically relevant molecules in the pathogenesis or management of many conditions, including congestive heart failure, hypertension, gastrointestinal and inflammatory disorders (irritable bowel syndrome, active gastritis, gastroparesis, and rheumatoid arthritis), atopic/allergic disorders (dermatitis, urticaria, and asthma), pregnancy and parturition (preeclampsia, spontaneous abortion, onset, and maintenance of effective labor), major depression and obesity. Safety trials for intravenous urocortin treatment have already begun for the treatment of congestive heart failure. Further understanding the unique functions of urocortin 1, urocortin 2, and urocortin 3 action may uncover other therapeutic opportunities.
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Affiliation(s)
- Éva M. Fekete
- Molecular and Integrative Neurosciences Department, The Scripps
Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
- Pécs University Medical School, 7602 Pécs,
Hungary
| | - Eric P. Zorrilla
- Molecular and Integrative Neurosciences Department, The Scripps
Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
- Harold L. Dorris Neurological Research Institute, The Scripps
Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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29
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Sullivan GM, Parsey RV, Kumar JSD, Arango V, Kassir SA, Huang YY, Simpson NR, Van Heertum RL, Mann JJ. PET Imaging of CRF1 with [11C]R121920 and [11C]DMP696: is the target of sufficient density? Nucl Med Biol 2007; 34:353-61. [PMID: 17499724 PMCID: PMC1933490 DOI: 10.1016/j.nucmedbio.2007.01.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2006] [Revised: 01/29/2007] [Accepted: 01/29/2007] [Indexed: 11/18/2022]
Abstract
AIM Overstimulation of the CRF type 1 receptor (CRF1) is implicated in anxiety and depressive disorders. The aim of this study was to investigate the in vivo binding characteristics of [11C]R121920 and [11C]DMP696 in the nonhuman primate for application in positron emission tomography (PET) studies of CRF1. METHODS PET imaging with the two novel CRF1 radioligands was performed in baboon. In vitro binding studies for CRF1 were performed in postmortem brain tissue of baboon and human to assess sufficiency of receptor density for PET. RESULTS Both [11C]R121920 and [11C]DMP696 distributed rapidly and uniformly throughout the brain. Washout was comparable across brain regions, without differences in volume of distribution between regions reported to have high and low in vitro CRF1 binding. Membrane-enriched tissue homogenate assay using [(125)I]Tyr(0)-sauvagine and specific CRF1 antagonists CP154,526 and SN003 in human occipital cortex yielded maximal binding (Bmax) of 63.3 and 147.3 fmol/mg protein, respectively, and in human cerebellar cortex yielded Bmax of 103.6 and 64.6 fmol/mg protein, respectively. Dissociation constants (K(D)) were subnanomolar. In baboon, specific binding was not detectable in the same regions; therefore, Bmax and K(D) were not measurable. Autoradiographic results were consistent except there was also detectable CRF1-specific binding in baboon cerebellum. CONCLUSION Neither [11C]R121920 nor [11C]DMP696 demonstrated quantifiable regional binding in vivo in baboon. In vitro results suggest CRF1 density in baboon may be insufficient for PET. Studies in man may generate more promising results due to the higher CRF1 density compared with baboon in cerebral cortex and cerebellum.
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Affiliation(s)
- Gregory M Sullivan
- Division of Neuroscience, Department of Psychiatry, New York State Psychiatric Institute, Columbia University, New York, NY 10032, USA.
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30
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Abstract
The past decade has witnessed a significant growth in the identification of allosteric modulators of G protein-coupled receptors (GPCRs), i.e., ligands that interact with binding sites that are topographically distinct from the orthosteric site recognized by the receptor's endogenous agonist. Because of their ability to modulate receptor conformations in the presence of orthosteric ligand, allosteric modulators can "fine-tune" classical pharmacological responses. This is advantageous in terms of a potential for engendering greater GPCR subtype-selectivity, but represents a significant challenge for detecting and validating allosteric behaviors. Although allosteric sites need not have evolved to accommodate endogenous ligands, there are a number of examples of where such modulators have been shown to contribute to physiological or pathophysiological processes. Studies are also beginning to unravel the structural basis of allosteric modulation of GPCRs. It remains to be determined whether such modulation represents interactions within monomers versus across dimers.
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Affiliation(s)
- Lauren T May
- Department of Pharmacology, University of Melbourne, 3010 Parkville, Victoria
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31
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Heise CE, Sullivan SK, Crowe PD. Scintillation proximity assay as a high-throughput method to identify slowly dissociating nonpeptide ligand binding to the GnRH receptor. ACTA ACUST UNITED AC 2007; 12:235-9. [PMID: 17208923 DOI: 10.1177/1087057106297362] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Many nonpeptide antagonists of the gonadotropin-releasing hormone (GnRH) receptor, as well as other drug targets, possess a broad range of dissociation kinetic rate constants. Current methods to accurately define kinetic rate parameters such as K(on) and K(off) are time and labor intensive, prompting the development of a screening assay to identify slowly dissociating compounds for follow-up rate constant determination. The authors measured inhibition binding constants (K(i)) for GnRH receptor antagonists after 30 min and 10 h of incubation and observed several compounds with markedly decreased K(i) values over time (Ki(30 min)/Ki(10 h) > 6). They used scintillation proximity assay technology to perform these binding experiments because this homogeneous assay does not have a fixed termination end point as does filtration binding, permitting successive readings to be taken from the same assay plate over an extended period of time. They also used a quantitative method of kinetic rate analysis to confirm that a large disparity between a compound's K(i) value at 30 min and 10 h could identify compounds that dissociate slowly. Thus, the K(i) ratio can be used to screen for and select compounds to test using more quantitative, albeit lower throughput methods to accurately define kinetic rate constants.
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Affiliation(s)
- Christopher E Heise
- Neurocrine Biosciences Inc, Department of Pharmacology, San Diego, CA 92130, USA.
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32
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Mesleh MF, Shirley WA, Heise CE, Ling N, Maki RA, Laura RP. NMR structural characterization of a minimal peptide antagonist bound to the extracellular domain of the corticotropin-releasing factor1 receptor. J Biol Chem 2006; 282:6338-46. [PMID: 17192263 DOI: 10.1074/jbc.m609816200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Natural peptide agonists of corticotrophin-releasing factor (CRF) receptors bind to the receptor by a two-site mechanism as follows: the carboxyl end of the ligand binds the N-terminal extracellular domain (ECD) of the receptor and the amino portion of the ligand binds the extracellular face of the seven transmembrane region. Recently, peptide antagonists homologous to the 12 C-terminal residues of CRF have been derived, which bind the CRF(1) receptor through an interaction with the ECD. Here we characterized the binding of a minimal 12-residue peptide antagonist while bound to the isolated ECD of the CRF(1) receptor. We have expressed and purified soluble and properly folded ECD independent from the seven-transmembrane region as a thioredoxin fusion protein in Escherichia coli. A model of the peptide antagonist, cyclic corticotrophin-releasing factor residues 30-41 (cCRF(30-41)), was calculated while bound to the recombinant ECD using transferred nuclear Overhauser effect spectroscopy. Although the peptide is unstructured in solution, it adopts an alpha-helical conformation when bound to the ECD. Residues of cCRF(30-41) comprising the binding interface with the ECD were mapped using saturation transfer difference NMR. Two hydrophobic residues (Met(38) and Ile(41)) as well as two amide groups (Asn(34) and the C-terminal amide) on one face of the helix defined the binding epitope of the antagonist. This epitope may be used as a starting point for development of non-peptide antagonists targeting the ECD of this receptor.
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Affiliation(s)
- Michael F Mesleh
- Department of Medicinal Chemistry, Neurocrine Biosciences, Inc., San Diego, California 92130, USA
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33
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34
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Berger H, Heinrich N, Wietfeld D, Bienert M, Beyermann M. Evidence that corticotropin-releasing factor receptor type 1 couples to Gs- and Gi-proteins through different conformations of its J-domain. Br J Pharmacol 2006; 149:942-7. [PMID: 17057757 PMCID: PMC2014684 DOI: 10.1038/sj.bjp.0706926] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE According to the two-domain model for the corticotropin-releasing factor receptor type 1 (CRF(1)), peptide antagonists bind to the N-terminal domain (N-domain), non-peptide antagonists to the transmembrane region (J-domain), whereas peptide agonists attach to both the N- and J-domain of the receptor to express activity. The aim of this study was to search for possible differences in the antagonism of the Gs- and Gi-protein coupling of CRF(1) by a peptide (alpha-helical CRF(9-41)) and non-peptide antagonist (antalarmin), to determine whether the conformational requirements of the activated CRF(1) states for Gs and Gi coupling are similar or different. EXPERIMENTAL APPROACH We studied the inhibitory effect of alpha-helical CRF(9-41) and antalarmin on the coupling of CRF(1) to Gs- and Gi-protein in human embryonic kidney cells, using the [(35)S]-GTPgammaS binding stimulation assay. KEY RESULTS The non-peptide antagonized the receptor coupling to Gs competitively but that to Gi noncompetitively, and its antagonistic potency was different for urocortin- and sauvagine-evoked G-protein activation. In contrast, the peptide antagonist exhibited uniformly competitive antagonism. CONCLUSIONS AND IMPLICATIONS The results allow us to extend the two-domain model of CRF(1) activation by assuming that CRF(1) agonists activate the receptor by binding to at least two ensembles of J-domain configurations which couple to Gs or Gi, that are in turn antagonized by a non-peptide antagonist competitively and allosterically, respectively. It is further concluded that the allosteric mechanism of non-peptide antagonism is not valid for the Gs-mediated physiological activities of CRF(1).
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MESH Headings
- Allosteric Regulation
- Amphibian Proteins
- Binding, Competitive
- Cell Line
- Corticotropin-Releasing Hormone/pharmacology
- Dose-Response Relationship, Drug
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- GTP-Binding Protein alpha Subunits, Gs/metabolism
- Guanosine 5'-O-(3-Thiotriphosphate)
- Hormone Antagonists/pharmacology
- Humans
- Models, Molecular
- Peptide Fragments/pharmacology
- Peptide Hormones
- Peptides/pharmacology
- Protein Conformation
- Protein Structure, Tertiary
- Pyrimidines/pharmacology
- Pyrroles/pharmacology
- Receptors, Corticotropin-Releasing Hormone/chemistry
- Receptors, Corticotropin-Releasing Hormone/drug effects
- Receptors, Corticotropin-Releasing Hormone/genetics
- Receptors, Corticotropin-Releasing Hormone/metabolism
- Signal Transduction/drug effects
- Transfection
- Urocortins
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Affiliation(s)
- H Berger
- Department of Peptide Chemistry/Biochemistry, Leibniz Institute of Molecular Pharmacology Berlin, Germany
| | - N Heinrich
- Department of Peptide Chemistry/Biochemistry, Leibniz Institute of Molecular Pharmacology Berlin, Germany
| | - D Wietfeld
- Department of Peptide Chemistry/Biochemistry, Leibniz Institute of Molecular Pharmacology Berlin, Germany
| | - M Bienert
- Department of Peptide Chemistry/Biochemistry, Leibniz Institute of Molecular Pharmacology Berlin, Germany
| | - M Beyermann
- Department of Peptide Chemistry/Biochemistry, Leibniz Institute of Molecular Pharmacology Berlin, Germany
- Author for correspondence:
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35
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Schwarz DA, Allen MM, Petroski RE, Pomeroy JE, Heise CE, Mistry MS, Selkirk JV, Nottebaum LM, Grey J, Zhang M, Goodfellow VS, Maki RA. Manipulation of small-molecule inhibitory kinetics modulates MCH-R1 function. Mol Cell Endocrinol 2006; 259:1-9. [PMID: 16987592 DOI: 10.1016/j.mce.2006.07.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2006] [Revised: 05/25/2006] [Accepted: 07/24/2006] [Indexed: 11/29/2022]
Abstract
The capacity of novel benzopyridazinone-based antagonists to inhibit MCH-R1 function, relative to their affinity for the receptor, has been investigated. Three compounds that differ by the addition of either a chlorine atom, or trifluoromethyl group, have nearly identical receptor affinities; however their abilities to inhibit receptor elicited signaling events, measured as a function of time, are dramatically altered. Both the chlorinated and trifluoromethyl modified compounds have a very slow on-rate to maximal functional inhibition relative to the unmodified base compound. A similar impact on inhibitory capacity can be achieved by modifying the side-chain composition at position 2.53 of the receptor; replacement of the native phenylalanine with alanine significantly reduces the amount of time required by the chlorinated compound to attain maximal functional inhibition. The primary attribute responsible for this alteration in inhibitory capacity appears to be the overall bulk of the amino acid at this position-substitution of the similarly sized amino acids leucine and tyrosine results in phenotypes that are indistinguishable from the wild type receptor. Finally, the impact of these differential inhibitory kinetics has been examined in cultured rat neurons by measuring the ability of the compounds to reverse MCH mediated inhibition of calcium currents. As observed using the cell expression models, the chlorinated compound has a diminished capacity to interfere with receptor function. Collectively, these data suggest that differential inhibitory on rates between a small-molecule antagonist and its target receptor can impact the ability of the compound to modify the biological response(s) elicited by the receptor.
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Affiliation(s)
- David A Schwarz
- Neurocrine Biosciences, Inc., Department of Molecular Biology, 12790 El Camino Real, San Diego, CA 92130, USA.
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36
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Sullivan SK, Hoare SRJ, Fleck BA, Zhu YF, Heise CE, Struthers RS, Crowe PD. Kinetics of nonpeptide antagonist binding to the human gonadotropin-releasing hormone receptor: Implications for structure–activity relationships and insurmountable antagonism. Biochem Pharmacol 2006; 72:838-49. [PMID: 16930559 DOI: 10.1016/j.bcp.2006.07.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Revised: 06/28/2006] [Accepted: 07/17/2006] [Indexed: 11/21/2022]
Abstract
Numerous nonpeptide ligands have been developed for the human gonadotropin-releasing hormone (GnRH) receptor as potential agents for treatment of disorders of the reproductive-endocrine axis. While the equilibrium binding of these ligands has been studied in detail, little is known of the kinetics of their receptor interaction. In this study we evaluated the kinetic structure-activity relationships (SAR) of uracil-series antagonists by measuring their association and dissociation rate constants. These constants were measured directly using a novel radioligand, [3H] NBI 42902, and indirectly for unlabeled ligands. Receptor association and dissociation of [3H] NBI 42902 was monophasic, with an association rate constant of 93+/-10 microM(-1) min(-1) and a dissociation rate constant of 0.16+/-0.02 h(-1) (t(1/2) of 4.3 h). Four unlabeled compounds were tested with varying substituents at the 2-position of the benzyl group at position 1 of the uracil (-F, -SO(CH3), -SO2(CH3) and -CF3). The nature of the substituent did not appreciably affect the association rate constant but varied the dissociation rate constant >50-fold (t(1/2) ranging from 52 min for -SO(CH3) to >43 h for -CF3). This SAR was poorly resolved in standard competition assays due to lack of equilibration. The functional consequences of the varying dissociation rate were investigated by measuring antagonism of GnRH-stimulated [3H] inositol phosphates accumulation. Slowly dissociating ligands displayed insurmountable antagonism (decrease of the GnRH E(max)) while antagonism by more rapidly dissociating ligands was surmountable (without effect on the GnRH E(max)). Therefore, evaluating the receptor binding kinetics of nonpeptide antagonists revealed SAR, not evident in standard competition assays, that defined at least in part the mode of functional antagonism by the ligands. These findings are of importance for the future definition of nonpeptide ligand SAR and for the identification of potentially useful slowly dissociating antagonists for the GnRH receptor.
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Affiliation(s)
- Susan K Sullivan
- Department of Pharmacology and Lead Discovery, Neurocrine Biosciences Inc., 12790 El Camino Real, San Diego, CA 92130, USA
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37
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Hauger RL, Risbrough V, Brauns O, Dautzenberg FM. Corticotropin releasing factor (CRF) receptor signaling in the central nervous system: new molecular targets. CNS & NEUROLOGICAL DISORDERS DRUG TARGETS 2006; 5:453-79. [PMID: 16918397 PMCID: PMC1925123 DOI: 10.2174/187152706777950684] [Citation(s) in RCA: 246] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Corticotropin-releasing factor (CRF) and the related urocortin peptides mediate behavioral, cognitive, autonomic, neuroendocrine and immunologic responses to aversive stimuli by activating CRF(1) or CRF(2) receptors in the central nervous system and anterior pituitary. Markers of hyperactive central CRF systems, including CRF hypersecretion and abnormal hypothalamic-pituitary-adrenal axis functioning, have been identified in subpopulations of patients with anxiety, stress and depressive disorders. Because CRF receptors are rapidly desensitized in the presence of high agonist concentrations, CRF hypersecretion alone may be insufficient to account for the enhanced CRF neurotransmission observed in these patients. Concomitant dysregulation of mechanisms stringently controlling magnitude and duration of CRF receptor signaling also may contribute to this phenomenon. While it is well established that the CRF(1) receptor mediates many anxiety- and depression-like behaviors as well as HPA axis stress responses, CRF(2) receptor functions are not well understood at present. One hypothesis holds that CRF(1) receptor activation initiates fear and anxiety-like responses, while CRF(2) receptor activation re-establishes homeostasis by counteracting the aversive effects of CRF(1) receptor signaling. An alternative hypothesis posits that CRF(1) and CRF(2) receptors contribute to opposite defensive modes, with CRF(1) receptors mediating active defensive responses triggered by escapable stressors, and CRF(2) receptors mediating anxiety- and depression-like responses induced by inescapable, uncontrollable stressors. CRF(1) receptor antagonists are being developed as novel treatments for affective and stress disorders. If it is confirmed that the CRF(2) receptor contributes importantly to anxiety and depression, the development of small molecule CRF(2) receptor antagonists would be therapeutically useful.
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Affiliation(s)
- Richard L Hauger
- San Diego VA Healthcare System, University of California San Diego, La Jolla, 929093-0603, USA.
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38
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Hoare SRJ, Brown BT, Santos MA, Malany S, Betz SF, Grigoriadis DE. Single amino acid residue determinants of non-peptide antagonist binding to the corticotropin-releasing factor1 (CRF1) receptor. Biochem Pharmacol 2006; 72:244-55. [PMID: 16750175 DOI: 10.1016/j.bcp.2006.04.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2006] [Accepted: 04/11/2006] [Indexed: 10/24/2022]
Abstract
The molecular interactions between non-peptide antagonists and the corticotropin-releasing factor type 1 (CRF1) receptor are poorly understood. A CRF1 receptor mutation has been identified that reduces binding affinity of the non-peptide antagonist NBI 27914 (M276I in transmembrane domain 5). We have investigated the mechanism of the mutation's effect using a combination of peptide and non-peptide ligands and receptor mutations. The M276I mutation reduced binding affinity of standard non-peptide antagonists 5-75-fold while having no effect on peptide ligand binding. We hypothesized that the side chain of isoleucine, beta-branched and so rotationally constrained when within an alpha-helix, introduces a barrier to non-peptide antagonist binding. In agreement with this hypothesis, mutation of M276 to the rotationally constrained valine produced similar reductions of affinity as M276I mutation, whereas mutation to leucine (with an unbranched beta-carbon) minimally affected non-peptide antagonist affinity. Mutation to alanine did not appreciably affect non-peptide antagonist affinity, implying the methionine side chain does not contribute directly to binding. Three observations suggested M276I/V mutations interfere with binding of the heterocyclic core of the compounds: (1) all compounds affected by M276I/V mutations possess a planar heterocyclic core. (2) None of the M276 mutations affected binding of an acylic compound. (3) The mutations differentially affected affinity of two compounds that differ only by core methylation. These findings imply that non-peptide antagonists, and specifically the heterocyclic core of such molecules, bind in the vicinity of M276 of the CRF1 receptor. M276 mutations did not affect peptide ligand binding and this residue is distant from determinants of peptide binding (predominantly in the extracellular regions), providing molecular evidence for non-overlapping (allosteric) binding sites for peptide and non-peptide ligands within the CRF1 receptor.
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Affiliation(s)
- Sam R J Hoare
- Department of Discovery Biology, Neurocrine Biosciences Inc., 12790 El Camino Real, San Diego, CA 92130, USA.
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39
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Millan MJ. Multi-target strategies for the improved treatment of depressive states: Conceptual foundations and neuronal substrates, drug discovery and therapeutic application. Pharmacol Ther 2006; 110:135-370. [PMID: 16522330 DOI: 10.1016/j.pharmthera.2005.11.006] [Citation(s) in RCA: 419] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Accepted: 11/28/2005] [Indexed: 12/20/2022]
Abstract
Major depression is a debilitating and recurrent disorder with a substantial lifetime risk and a high social cost. Depressed patients generally display co-morbid symptoms, and depression frequently accompanies other serious disorders. Currently available drugs display limited efficacy and a pronounced delay to onset of action, and all provoke distressing side effects. Cloning of the human genome has fuelled expectations that symptomatic treatment may soon become more rapid and effective, and that depressive states may ultimately be "prevented" or "cured". In pursuing these objectives, in particular for genome-derived, non-monoaminergic targets, "specificity" of drug actions is often emphasized. That is, priority is afforded to agents that interact exclusively with a single site hypothesized as critically involved in the pathogenesis and/or control of depression. Certain highly selective drugs may prove effective, and they remain indispensable in the experimental (and clinical) evaluation of the significance of novel mechanisms. However, by analogy to other multifactorial disorders, "multi-target" agents may be better adapted to the improved treatment of depressive states. Support for this contention is garnered from a broad palette of observations, ranging from mechanisms of action of adjunctive drug combinations and electroconvulsive therapy to "network theory" analysis of the etiology and management of depressive states. The review also outlines opportunities to be exploited, and challenges to be addressed, in the discovery and characterization of drugs recognizing multiple targets. Finally, a diversity of multi-target strategies is proposed for the more efficacious and rapid control of core and co-morbid symptoms of depression, together with improved tolerance relative to currently available agents.
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Affiliation(s)
- Mark J Millan
- Institut de Recherches Servier, Centre de Recherches de Croissy, Psychopharmacology Department, 125, Chemin de Ronde, 78290-Croissy/Seine, France.
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Abstract
Allosteric modulation of membrane receptors has been intensively studied in the past three decades and is now considered to be an important indirect mechanism for the control of receptor function. The allosteric site on the GABA(A) receptor is the target for the most widely prescribed sleep medicines, the benzodiazepines. Cinacalcet, an allosteric enhancer of the calcium-sensing receptor, is used to treat secondary hyperparathyroidism. Allosteric ligands might be especially valuable to control receptors for which the design of selective orthosteric agonists or antagonists has been elusive, such as muscarinic acetylcholine receptors.
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Affiliation(s)
- Zhan-Guo Gao
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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Kiddoo DA, Valentino RJ, Zderic S, Ganesh A, Leiser SC, Hale L, Grigoriadis DE. Impact of state of arousal and stress neuropeptides on urodynamic function in freely moving rats. Am J Physiol Regul Integr Comp Physiol 2006; 290:R1697-706. [PMID: 16439667 DOI: 10.1152/ajpregu.00742.2005] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Corticotropin-releasing factor (CRF) is a neurotransmitter in Barrington's nucleus neurons. These neurons can coregulate parasympathetic tone to the bladder (to modulate micturition) and brain noradrenergic activity (to affect arousal). To identify the role of CRF in the regulation of micturition, the effects of CRF agonists and antagonists on urodynamics in the unanesthetized rat were characterized. Rats were implanted with bladder and intrathecal or intraperitoneal catheters under isoflurane anesthesia. Cystometry was performed in the unanesthetized, unrestrained state at least 24 h later. In some cases, cortical electroencephalographic activity (EEG) was recorded simultaneously to assess arousal state. During cystometry, the state of arousal often shifted between waking and sleeping and urodynamic function changed depending on the state. Micturition threshold, bladder capacity, and micturition volume were all increased during sleep. The CRF1/CRF2 receptor agonists CRF and urocortin 2 increased bladder capacity and micturition volume in awake but not in sleeping rats. Conversely, the CRF1 receptor antagonists antalarmin and NBI-30775 increased urinary frequency and decreased bladder capacity in awake rats. The present results demonstrate a profound effect of the state of arousal on urodynamic function and suggest that simultaneous monitoring of EEG and cystometry may provide a useful model for studying nocturnal enuresis and other urinary disorders. In addition, the results provide evidence for an inhibitory influence of CRF in the spinal pathway on micturition. Targeting the CRF system in the spinal cord may provide a novel approach for treating urinary disorders.
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Affiliation(s)
- Darcie A Kiddoo
- Department of Surgery, The Children's Hospital of Philadelphia, 402C Abramson Bldg., Osler Cr., Philadelphia, PA 19104, USA
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Dean T, Linglart A, Mahon MJ, Bastepe M, Jüppner H, Potts JT, Gardella TJ. Mechanisms of ligand binding to the parathyroid hormone (PTH)/PTH-related protein receptor: selectivity of a modified PTH(1-15) radioligand for GalphaS-coupled receptor conformations. Mol Endocrinol 2005; 20:931-43. [PMID: 16339275 PMCID: PMC3242416 DOI: 10.1210/me.2005-0349] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Mechanisms of ligand binding to the PTH/PTHrP receptor (PTHR) were explored using PTH fragment analogs as radioligands in binding assays. In particular, the modified amino-terminal fragment analog, (125)I-[Aib(1,3),Nle8,Gln10,homoarginine11,Ala12,Trp14,Tyr15]rPTH(1-15)NH2, (125)I-[Aib(1,3),M]PTH(1-15), was used as a radioligand that we hypothesized to bind solely to the juxtamembrane (J) portion of the PTHR containing the extracellular loops and transmembrane helices. We also employed (125)I-PTH(1-34) as a radioligand that binds to both the amino-terminal extracellular (N) and J domains of the PTHR. Binding was examined in membranes derived from cells expressing either wild-type or mutant PTHRs. We found that the binding of (125)I-[Aib(1,3),M]PTH(1-15) to the wild-type PTHR was strongly (approximately 90%) inhibited by guanosine 5'-O-(3-thio)triphosphate (GTPgammaS), whereas the binding of (125)I-PTH(1-34) was only mildly (approximately 25%) inhibited by GTPgammaS. Of these two radioligands, only (125)I-[Aib(1,3),M]PTH(1-15) bound to PTHR-delNt, which lacks most of the receptor's N domain, and again this binding was strongly inhibited by GTPgammaS. Binding of (125)I-[Aib(1,3),M]PTH(1-15) to the constitutively active receptor, PTHR-H223R, was only mildly (approximately 20%) inhibited by GTPgammaS, as was the binding of (125)I-PTH(1-34). In membranes prepared from cells lacking Galpha(S) via knockout mutation of Gnas, no binding of (125)I-[Aib(1,3),M]PTH(1-15) was observed, but binding of (125)I-[Aib(1,3),M]PTH(1-15) was recovered by virally transducing the cells to heterologously express Galpha(S). (125)I-PTH(1-34) bound to the membranes with or without Galpha(S). The overall findings confirm the hypothesis that (125)I-[Aib(1,3),M]PTH(1-15) binds solely to the J domain of the PTHR. They further show that this binding is strongly dependent on coupling of the receptor to Galpha(S)-containing heterotrimeric G proteins, whereas the binding of (125)I-PTH(1-34) can occur in the absence of such coupling. Thus, (125)I-[Aib(1,3),M]PTH(1-15) appears to function as a selective probe of Galpha(S)-coupled, active-state PTHR conformations.
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MESH Headings
- Animals
- COS Cells
- Cell Line
- Cell Membrane/metabolism
- Chlorocebus aethiops
- GTP-Binding Protein alpha Subunits, Gs/chemistry
- GTP-Binding Protein alpha Subunits, Gs/deficiency
- GTP-Binding Protein alpha Subunits, Gs/genetics
- GTP-Binding Protein alpha Subunits, Gs/metabolism
- Humans
- Kinetics
- LLC-PK1 Cells
- Ligands
- Parathyroid Hormone/metabolism
- Peptide Fragments/metabolism
- Protein Conformation
- Radioligand Assay
- Receptor, Parathyroid Hormone, Type 1/chemistry
- Receptor, Parathyroid Hormone, Type 1/genetics
- Receptor, Parathyroid Hormone, Type 1/metabolism
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Swine
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Affiliation(s)
- Thomas Dean
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA
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43
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Gross RS, Guo Z, Dyck B, Coon T, Huang CQ, Lowe RF, Marinkovic D, Moorjani M, Nelson J, Zamani-Kord S, Grigoriadis DE, Hoare SRJ, Crowe PD, Bu JH, Haddach M, McCarthy J, Saunders J, Sullivan R, Chen T, Williams JP. Design and synthesis of tricyclic corticotropin-releasing factor-1 antagonists. J Med Chem 2005; 48:5780-93. [PMID: 16134945 DOI: 10.1021/jm049085v] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Antagonists of the corticotropin-releasing factor (CRF) neuropeptide should prove to be effective in treating stress and anxiety-related disorders. In an effort to identify antagonists with improved physicochemical properties, new tricyclic CRF(1) antagonists were designed, synthesized, and tested for biological activity. As a result of studies aimed at establishing a relationship between structure and CRF(1) binding affinity, NBI 35965 (12a) was identified as a high-affinity antagonist with a pK(i) value of 8.5. Compound 12a proved to be a functional CRF(1) antagonist with pIC(50) values of 7.1 and 6.9 in the in vitro CRF-stimulated cAMP accumulation and ACTH production assays, respectively, and 12a also reduced CRF or stress induced ACTH production in vivo.
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Affiliation(s)
- Raymond S Gross
- Department of Medicinal Chemistry, Neurocrine Biosciences, 12790 El Camino Real, San Diego, California 92130, USA
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44
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Seymour PL, Dettloff SL, Jones JE, Wade GN. Corticotropin-releasing factor receptor subtypes mediating nutritional suppression of estrous behavior in Syrian hamsters. Am J Physiol Regul Integr Comp Physiol 2005; 289:R418-R423. [PMID: 15831766 DOI: 10.1152/ajpregu.00168.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Caloric deprivation inhibits reproduction, including copulatory behaviors, in female mammals. Decreases in metabolic fuel availability are detected in the hindbrain, and this information is relayed to the forebrain circuits controlling estrous behavior by neuropeptide Y (NPY) projections. In the forebrain, the nutritional inhibition of estrous behavior appears to be mediated by corticotropin-releasing factor (CRF) or urocortin-signaling systems. Intracerebroventricular (ICV) infusion of the CRF antagonist, astressin, prevents the suppression of lordosis by food deprivation and by NPY treatment in Syrian hamsters. These experiments sought to determine which CRF receptor type(s) is involved. ICV infusion of the CRF receptor subtype CRFR2-selective agonists urocortin 2 and 3 (UCN2, UCN3) inhibited sexual receptivity in hormone-primed, ovariectomized hamsters. Furthermore, the CRFR2-selective antagonist, astressin 2B, prevented the inhibition of estrous behavior by UCN2 and by NPY, consistent with a role for CRFR2. On the other hand, astressin 2B did not prevent the inhibition of behavior induced by 48-h food deprivation or ICV administration of CRF, a mixed CRFR1 and CRFR2 agonist, suggesting that activation of CRFR1 signaling is sufficient to inhibit sexual receptivity in hamsters. Although administration of CRFR1-selective antagonists (NBI-27914 and CP-154,526) failed to reverse the inhibition of receptivity by CRF treatment, we could not confirm their biological effectiveness in hamsters. The most parsimonious interpretation of these findings is that, although NPY inhibits estrous behavior via downstream CRFR2 signaling, food deprivation may exert its inhibition via both CRFR1 and CRFR2 and that redundant neuropeptide systems may be involved.
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Affiliation(s)
- Patricia L Seymour
- Center for Neuroendocrine Studies, University of Massachusetts, 135 Hicks Way, Amherst, MA 01003, USA
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45
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Abstract
Preclinical studies suggest that the brain corticotropin-releasing factor (CRF) systems mediate anxiety-like behavioural and somatic responses through actions at the CRF1 receptor. CRF1 antagonists block the anxiogenic-like effects of CRF and stress in animal models. Cerebrospinal fluid levels of CRF are elevated in some anxiety disorders and normalise with effective treatment, further implicating CRF systems as a therapeutic target. Prototypical CRF1 antagonists are highly lipophilic, non-competitive antagonists of peptide ligands. Modification of the chemotype and the identification of novel pharmacophores are yielding more drug-like structures with increased hydrophilicity at physiological pHs. Newer compounds exhibit improved solubility, pharmacokinetic properties, potency and efficacy. Several clinical candidates have entered Phase I/II trials. However, unmet challenges await resolution during further discovery, clinical development and therapeutic application of CRF1 antagonists.
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Affiliation(s)
- Eric P Zorrilla
- Department of Neuropharmacology, The Scripps Research Institute, CVN-7, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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46
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Markison S, Foster AC, Chen C, Brookhart GB, Hesse A, Hoare SRJ, Fleck BA, Brown BT, Marks DL. The regulation of feeding and metabolic rate and the prevention of murine cancer cachexia with a small-molecule melanocortin-4 receptor antagonist. Endocrinology 2005; 146:2766-73. [PMID: 15774557 DOI: 10.1210/en.2005-0142] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cachexia is metabolic disorder characterized by anorexia, an increased metabolic rate, and loss of lean body mass. It is a relatively common disorder, and is a pathological feature of diseases such as cancer, HIV infection, and renal failure. Recent studies have demonstrated that cachexia brought about by a variety of illnesses can be attenuated or reversed by blocking activation of the melanocortin 4 subtype receptor (MC4-R) within the central nervous system. Although the potential use of central MC4-R antagonists for the treatment of cachexia was supported by these studies, utility was limited by the need to deliver these agents intracerebroventricularly. In the current study, we present a series of experiments demonstrating that peripheral administration of a small molecule MC4-R antagonist can effectively stimulate daytime (satiated) food intake as well as decrease basal metabolic rate in normal animals. Furthermore, this compound attenuated cachexia and preserved lean body mass in a murine cancer model. These data clearly demonstrate the potential of small molecule MC4-R antagonists in the treatment of cachexia and underscore the importance of melanocortin signaling in the development of this metabolic disorder.
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Affiliation(s)
- Stacy Markison
- Department of Pediatrics, Mailcode CDRCP, 707 Southwest Gaines Road, Portland, Oregon 97239, USA.
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47
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Heise CE, Pahuja A, Hudson SC, Mistry MS, Putnam AL, Gross MM, Gottlieb PA, Wade WS, Kiankarimi M, Schwarz D, Crowe P, Zlotnik A, Alleva DG. Pharmacological characterization of CXC chemokine receptor 3 ligands and a small molecule antagonist. J Pharmacol Exp Ther 2005; 313:1263-71. [PMID: 15761110 DOI: 10.1124/jpet.105.083683] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The CXC chemokine receptor 3 (CXCR3) is predominantly expressed on T helper type 1 (Th1) cells that are involved in inflammatory diseases. The three CXCR3 ligands CXCL9, CXCL10, and CXCL11 are produced at sites of inflammation and elicit migration of pathological Th1 cells. Here, we are the first to characterize the pharmacological potencies and specificity of a CXCR3 antagonist, N-1R-[3-(4-ethoxy-phenyl)-4-oxo-3,4-dihydro-pyrido[2,3-d]pyrimidin-2-yl]-ethyl-N-pyridin-3-ylmethyl-2-(4-fluoro-3-trifluoromethyl-phenyl)-acetamide (NBI-74330), from the T487 small molecule series. NBI-74330 demonstrated potent inhibition of [(125)I]CXCL10 and [(125)I]CXCL11 specific binding (K(i) of 1.5 and 3.2 nM, respectively) and of functional responses mediated by CXCR3, such as ligand-induced guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPgammaS) binding, calcium mobilization, and cellular chemotaxis (IC(50) of 7 to 18 nM). NBI-74330 was selective for CXCR3 because it showed no significant inhibition of chemotactic responses to other chemokines and did not inhibit radioligand binding to a panel of nonchemokine G-protein coupled receptors. There was a striking difference in potencies among the three CXCR3 ligands, with CXCL11 >> CXCL10 > CXCL9. A comparison of the rank order of K(i) values with the rank order of monocyte production levels of these three ligands revealed a precise inverse correlation, suggesting that the weaker receptor affinities of CXCL9 and CXCL10 were physiologically compensated for by an elevated expression, perhaps to maintain effectiveness of each ligand under physiological conditions.
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48
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Perry SJ, Junger S, Kohout TA, Hoare SRJ, Struthers RS, Grigoriadis DE, Maki RA. Distinct Conformations of the Corticotropin Releasing Factor Type 1 Receptor Adopted following Agonist and Antagonist Binding Are Differentially Regulated. J Biol Chem 2005; 280:11560-8. [PMID: 15653688 DOI: 10.1074/jbc.m412914200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The corticotropin releasing factor (CRF) type 1 receptor (CRF1) is a class B family G protein-coupled receptor that regulates the hypothalamic-pituitary-adrenal stress axis. Astressin is an amino-terminal truncated analog of CRF that retains high affinity binding to the extracellular domain of the receptor and is believed to act as a neutral competitive antagonist of receptor activation. Here we show that despite being unable to activate the CRF1 receptor, astressin binding results in the internalization of the receptor. Furthermore, entirely different pathways of internalization of CRF1 receptors are utilized following CRF and astressin binding. CRF causes the receptor to be phosphorylated, recruit beta-arrestin2, and to be internalized rapidly, likely through clathrin-coated pits. Astressin, however, fails to induce receptor phosphorylation or beta-arrestin2 recruitment, and internalization is slow and occurs through a pathway that is insensitive to inhibitors of clathrin-coated pits and caveolae. The fate of the internalized receptors also differs because only CRF-induced internalization results in receptor down-regulation. Furthermore, we present evidence that for astressin to induce internalization it must interact with both the extracellular amino terminus and the juxtamembrane domain of the receptor. Astressin binds with 6-fold higher affinity to full-length CRF1 receptors than to a chimeric protein containing only the extracellular domain attached to the transmembrane domain of the activin IIB receptor, yet two 12-residue analogs of astressin have similar affinities for both proteins but are unable to induce receptor internalization. These data demonstrate that agonists and antagonists for CRF1 receptors promote distinct conformations, which are then differentially regulated.
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Affiliation(s)
- Stephen J Perry
- Department of Molecular Biology, Neurocrine Biosciences Inc., San Diego, California 92130, USA.
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49
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Hoare SRJ, Sullivan SK, Fan J, Khongsaly K, Grigoriadis DE. Peptide ligand binding properties of the corticotropin-releasing factor (CRF) type 2 receptor: pharmacology of endogenously expressed receptors, G-protein-coupling sensitivity and determinants of CRF2 receptor selectivity. Peptides 2005; 26:457-70. [PMID: 15652653 DOI: 10.1016/j.peptides.2004.10.019] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2004] [Revised: 10/15/2004] [Accepted: 10/15/2004] [Indexed: 10/26/2022]
Abstract
The CRF2 receptor is involved in stress responses, cardiovascular function and gastric motility. Endogenous agonists (urocortin (UCN) 2, UCN 3) and synthetic antagonists (astressin2-B, antisauvagine-30) are selective for CRF2 over the CRF1 receptor. Peptide ligand binding properties of the CRF2 receptor require further investigation, including ligand affinity for endogenously expressed receptors, the effect of receptor-G-protein coupling on ligand affinity, and the molecular basis of ligand selectivity. Ligand affinity for rat CRF(2a) in olfactory bulb and CRF(2b) in A7r5 cells was similar to that for the cloned human CRF(2a) receptor (within three-fold), except for oCRF (9.4- and 5.4-fold higher affinity in olfactory bulb and A7r5 cells, respectively). Receptor-G-protein uncoupling reduced agonist affinity only 1.2- to 6.5-fold (compared with 92-1300-fold for the CRF1 receptor). Ligand selectivity mechanisms were investigated using chimeric CRF2/CRF1 receptors. The juxtamembrane receptor domain determined selectivity of antisauvagine-30, the N-terminal-extracellular domain contributed to selectivity of UCN 3, and both domains contributed to selectivity of UCN 2 and astressin2-B. Therefore ligands differ in the contribution of receptor domains to their selectivity, and CRF2-selective antagonists bind the juxtamembrane domain. These findings will be important for identifying the CRF2 receptor in tissues and for developing ligands targeting the receptor, both of which will be useful in identifying the emerging physiological functions of the CRF2 receptor.
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Affiliation(s)
- Sam R J Hoare
- Department of Pharmacology, Neurocrine Biosciences Inc., 12790 El Camino Real, San Diego, CA 92130, USA.
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Dautzenberg FM, Wille S. Binding differences of human and amphibian corticotropin-releasing factor type 1 (CRF(1)) receptors: identification of amino acids mediating high-affinity astressin binding and functional antagonism. ACTA ACUST UNITED AC 2005; 118:165-73. [PMID: 15003833 DOI: 10.1016/j.regpep.2003.12.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2003] [Accepted: 12/23/2003] [Indexed: 11/26/2022]
Abstract
The corticotropin-releasing factor (CRF) type 1 receptors (CRF(1)) from human (hCRF(1)) and Xenopus (xCRF(1)) differ from one another by their agonist- and antagonist-binding preference. While the agonist-binding site of the xCRF(1) receptor has been mapped, the amino acids that mediate binding of the potent peptide antagonist astressin are unknown. By constructing receptor chimeras followed by site-directed mutagenesis, the astressin-binding site of the xCRF(1) receptor was located between residues 76 and 83. This region partially overlaps with the agonist-selective domain of the xCRF(1) receptor (residues 76-89). Mutagenesis of the amphibian residues Gln(76), Gly(81) and Val(83) to the human sequence (Arg(76)Asn(81)Gly(83)) generated a receptor mutant that bound astressin with even higher affinity than the native hCRF(1) receptor. An amino acid doublet (Glu(70)Tyr(71)) that is conserved in the xCRF(1) and hCRF(2(a)) receptor after incorporation into the hCRF(1) receptor sequence was found to facilitate antagonist binding up to 15-fold higher. In agreement with the binding data, astressin was a more potent functional antagonist at receptors expressing the Glu(70)Tyr(71) motif. These data show that the agonist- and antagonist-binding sites of the hCRF(1) receptor partially overlap and that two amino acids within the N terminus of the hCRF(1) receptor negatively influence binding and functional antagonism of astressin.
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