Pharmacological Characterization of Low Molecular Weight Biased Agonists at the Follicle Stimulating Hormone Receptor

Effects and risk assessment of halogenated bisphenol A derivatives on human follicle stimulating hormone receptor: An interdisciplinary study

Halogenated bisphenol A (BPA) derivatives are produced during disinfection treatment of drinking water or are synthesized as flame retardants (TCBPA or TBBPA). BPA is considered as an endocrine disruptor especially on human follicle-stimulating hormone receptor (FSHR). Using a global experimental approach, we assessed the effect of halogenated BPA derivatives on FSHR activity and estimated the risk of halogenated BPA derivatives to the reproductive health of exposed populations. For the first time, we show that FSHR binds halogenated BPA derivatives, at 10 nM, a concentration lower than those requires to modulate the activity of nuclear receptors and/or steroidogenesis enzymes. Indeed, bioluminescence assays show that FSHR response is lowered up to 42.36 % in the presence of BPA, up to 32.79 % by chlorinated BPA derivatives and up to 27.04 % by brominated BPA derivatives, at non-cytotoxic concentrations and without modification of basal receptor activity. Moreover, molecular docking, molecular dynamics simulations, and site-directed mutagenesis experiments demonstrate that the halogenated BPA derivatives bind the FSHR transmembrane domain reducing the signal transduction efficiency which lowers the cellular cAMP production and in fine disrupts the physiological effect of FSH. The potential reproductive health risk of exposed individuals was estimated by comparing urinary concentrations (through a collection of human biomonitoring data) with the lowest effective concentrations derived from in vitro cell assays. Our results suggest a potentially high concern for the risk of inhibition of the FSHR pathway. This global approach based on FSHR activity could enable the rapid characterization of the toxicity of halogenated BPA derivatives (or other compounds) and assess the associated risk of exposure to these halogenated BPA derivatives.

Deciphering the comprehensive knowledgebase landscape featuring infertility with IDDB Xtra

Infertility affects ∼15% of couples globally and half of cases are related to genetic disorders. Despite growing data and unprecedented improvements in high-throughput sequencing technologies, accumulated fertility-related issues concerning genetic diagnosis and potential treatment are urgent to be solved. However, there is a lack of comprehensive platforms that characterise various infertility-related records to provide research applications for exploring infertility in-depth and genetic counselling of infertility couple. To solve this problem, we provide IDDB Xtra by further integrating phenotypic manifestations, genomic datasets, epigenetics, modulators in collaboration with numerous interactive tools into our previous infertility database, IDDB. IDDB Xtra houses manually-curated 2369 genes of human and nine model organisms, 273 chromosomal abnormalities, 884 phenotypes, 60 genomic datasets, 464 epigenetic records, 1144 modulators relevant to infertility diagnosis and treatment. Additionally, IDDB Xtra incorporated customized graphical applications for researchers and clinicians to decipher in-depth disease mechanisms from the perspectives of developmental atlas, mutation effects, and clinical manifestations. Users can browse genes across developmental stages of human and mouse, filter candidate genes, mine potential variants and retrieve infertility biomedical network in an intuitive web interface. In summary, IDDB Xtra not only captures valuable research and data, but also provides useful applications to facilitate the genetic counselling and drug discovery of infertility. IDDB Xtra is freely available at https://mdl.shsmu.edu.cn/IDDB/and http://www.allostery.net/IDDB.

A single-domain intrabody targeting the follicle-stimulating hormone receptor impacts FSH-induced G protein-dependent signalling

Intracellular variable fragments of heavy-chain antibody from camelids (intra-VHH) have been successfully used as chaperones to solve the 3D structure of active G protein-coupled receptors bound to their transducers. However, their effect on signalling has been poorly explored, although they may provide a better understanding of the relationships between receptor conformation and activity. Here, we isolated and characterized iPRC1, the first intra-VHH recognizing a member of the large glycoprotein hormone receptor family, the follicle-stimulating hormone receptor (FSHR). This intra-VHH recognizes the FSHR third intracellular loop and decreases cAMP production in response to FSH, without altering Gαs recruitment. Hence, iPRC1 behaves as an allosteric modulator and provides a new tool to complete structure/activity studies performed thus far on this receptor.

Allosteric modulation of gonadotropin receptors

Gonadotropins regulate reproductive functions by binding to G protein-coupled receptors (FSHR and LHCGR) expressed in the gonads. They activate multiple, cell-specific signalling pathways, consisting of ligand-dependent intracellular events. Signalling cascades may be modulated by synthetic compounds which bind allosteric sites of FSHR and LHCGR or by membrane receptor interactions. Despite the hormone binding to the orthosteric site, allosteric ligands, and receptor heteromerizations may reshape intracellular signalling pattern. These molecules act as positive, negative, or neutral allosteric modulators, as well as non-competitive or inverse agonist ligands, providing a set of new compounds of a different nature and with unique pharmacological characteristics. Gonadotropin receptor allosteric modulation is gathering increasing interest from the scientific community and may be potentially exploited for clinical purposes. This review summarizes the current knowledge on gonadotropin receptor allosteric modulation and their potential, clinical use.

Intracellular VHHs to monitor and modulate GPCR signaling

Single-domain antibody fragments, also known as VHHs or nanobodies, have opened promising avenues in therapeutics and in exploration of intracellular processes. Because of their unique structural properties, they can reach cryptic regions in their cognate antigen. Intracellular VHHs/antibodies primarily directed against cytosolic proteins or transcription factors have been described. In contrast, few of them target membrane proteins and even less recognize G protein-coupled receptors. These receptors are major therapeutic targets, which reflects their involvement in a plethora of physiological responses. Hence, they elicit a tremendous interest in the scientific community and in the industry. Comprehension of their pharmacology has been obscured by their conformational complexity, that has precluded deciphering their structural properties until the early 2010's. To that respect, intracellular VHHs have been instrumental in stabilizing G protein-coupled receptors in active conformations in order to solve their structure, possibly bound to their primary transducers, G proteins or β-arrestins. In contrast, the modulatory properties of VHHs recognizing the intracellular regions of G protein-coupled receptors on the induced signaling network have been poorly studied. In this review, we will present the advances that the intracellular VHHs have permitted in the field of GPCR signaling and trafficking. We will also discuss the methodological hurdles that linger the discovery of modulatory intracellular VHHs directed against GPCRs, as well as the opportunities they open in drug discovery.

Gonadotropin Cell Transduction Mechanisms

The intention of this Special Edition was to collect review and original research articles that illustrate and stimulate the growing efforts to highlight the mechanisms of action of gonadotropins, as well as deepen our understanding of their biological roles in health and disease, aiming at revealing novel therapeutic opportunities in reproductive and regenerative medicine [...].

Follicle-Stimulating Hormone Induces Lipid Droplets via Gαi/o and β-Arrestin in an Endometrial Cancer Cell Line

Follicle-stimulating hormone (FSH) and its G protein-coupled receptor, FSHR, represents a paradigm for receptor signaling systems that activate multiple and complex pathways. Classically, FSHR activates Gαs to increase intracellular levels of cAMP, but its ability to activate other G proteins, and β-arrestin-mediated signaling is well documented in many different cell systems. The pleiotropic signal capacity of FSHR offers a mechanism for how FSH drives multiple and dynamic downstream functions in both gonadal and non-gonadal cell types, including distinct diseases, and how signal bias may be achieved at a pharmacological and cell system-specific manner. In this study, we identify an additional mechanism of FSH-mediated signaling and downstream function in the endometrial adenocarcinoma Ishikawa cell line. While FSH did not induce increases in cAMP levels, this hormone potently activated pertussis toxin sensitive Gαi/o signaling. A selective allosteric FSHR ligand, B3, also activated Gαi/o signaling in these cells, supporting a role for receptor-mediated activation despite the low levels of FSHR mRNA. The low expression levels may attribute to the lack of Gαs/cAMP signaling as increasing FSHR expression resulted in FSH-mediated activation of the Gαs pathway. Unlike prior reports for FSH-mediated Gαs/cAMP signaling, FSH-mediated Gαi/o signaling was not affected by inhibition of dynamin-dependent receptor internalization. While chronic FSH did not alter cell viability, FSH was able to increase lipid droplet size. The β-arrestins are key adaptor proteins known to regulate FSHR signaling. Indeed, a rapid, FSH-dependent increase in interactions between β-arrestin1 and Gαi1 was observed via NanoBiT complementation in Ishikawa cells. Furthermore, both inhibition of Gαi/o signaling and siRNA knockdown of β-arrestin 1/2 significantly reduced FSH-induced lipid droplet accumulation, implying a role for a Gαi/o/β-arrestin complex in FSH functions in this cell type. As FSH/FSHR has been implicated in distinct hormone-dependent cancers, including endometrial cancer, analysis of the cancer genome database from 575 human endometrial adenocarcinoma tumors revealed that a subpopulation of samples expressed FSHR. Overall, this study highlights a novel mechanism for FSHR signal pleiotropy that may be exploited for future personalized therapeutic approaches.