Steuernagel, L;Lam, BYH;Klemm, P;Dowsett, GKC;Bauder, CA;Tadross, JA;Hitschfeld, TS;Del Rio Martin, A;Chen, W;de Solis, AJ;Fenselau, H;Davidsen, P;Cimino, I;Kohnke, SN;Rimmington, D;Coll, AP;Beyer, A;Yeo, GSH;Brüning, JC;
PMID: 36266547 | DOI: 10.1038/s42255-022-00657-y
The hypothalamus plays a key role in coordinating fundamental body functions. Despite recent progress in single-cell technologies, a unified catalog and molecular characterization of the heterogeneous cell types and, specifically, neuronal subtypes in this brain region are still lacking. Here, we present an integrated reference atlas, 'HypoMap,' of the murine hypothalamus, consisting of 384,925 cells, with the ability to incorporate new additional experiments. We validate HypoMap by comparing data collected from Smart-Seq+Fluidigm C1 and bulk RNA sequencing of selected neuronal cell types with different degrees of cellular heterogeneity. Finally, via HypoMap, we identify classes of neurons expressing glucagon-like peptide-1 receptor (Glp1r) and prepronociceptin (Pnoc), and validate them using single-molecule in situ hybridization. Collectively, HypoMap provides a unified framework for the systematic functional annotation of murine hypothalamic cell types, and it can serve as an important platform to unravel the functional organization of hypothalamic neurocircuits and to identify druggable targets for treating metabolic disorders.
Ali Marandi Ghoddousi, R;Magalong, VM;Kamitakahara, AK;Levitt, P;
PMID: 36313803 | DOI: 10.1016/j.crmeth.2022.100316
Spatial gene expression, achieved classically through in situ hybridization, is a fundamental tool for topographic phenotyping of cell types in the nervous system. Newly developed techniques allow for visualization of multiple mRNAs at single-cell resolution and greatly expand the ability to link gene expression to tissue topography, yet there are challenges in efficient quantification and analysis of these high-dimensional datasets. We have therefore developed the single-cell automated multiplex pipeline for RNA (SCAMPR), facilitating rapid and accurate segmentation of neuronal cell bodies using a dual immunohistochemistry-RNAscope protocol and quantification of low- and high-abundance mRNA signals using open-source image processing and automated segmentation tools. Proof of principle using SCAMPR focused on spatial mapping of gene expression by peripheral (vagal nodose) and central (visual cortex) neurons. The analytical effectiveness of SCAMPR is demonstrated by identifying the impact of early life stress on gene expression in vagal neuron subtypes.
El Eid, L;Reynolds, CA;Tomas, A;Ben Jones, ;
PMID: 36007775 | DOI: 10.1016/j.phrs.2022.106411
Glucagon-like peptide-1 receptor (GLP-1R) is a well-studied incretin hormone receptor and target of several therapeutic drugs for type 2 diabetes (T2D), obesity and, more recently, cardiovascular disease. Some signalling pathways downstream of GLP-1R may be responsible for drug adverse effects such as nausea, while others mediate therapeutic outcomes of incretin-based T2D therapeutics. Understanding the interplay between different factors that alter signalling, trafficking, and receptor activity, including biased agonism, single nucleotide polymorphisms and structural modifications is key to develop the next-generation of personalised GLP-1R agonists. However, these interactions remain poorly described, especially for novel therapeutics such as dual and tri-agonists that target more than one incretin receptor. Comparison of GLP-1R structures in complex with G proteins and different peptide and non-peptide agonists has revealed novel insights into important agonist-residue interactions and networks crucial for receptor activation, recruitment of G proteins and engagement of specific signalling pathways. Here, we review the latest knowledge on GLP-1R structure and activation, providing structural evidence for biased agonism and delineating important networks associated with this phenomenon. We survey current biased agonists and multi-agonists at different stages of development, highlighting possible challenges in their translational potential. Lastly, we discuss findings related to non-synonymous genomic variants of GLP1R and the functional importance of specific residues involved in GLP-1R function. We propose that studies of GLP-1R polymorphisms, and specifically their effect on receptor dynamics and pharmacology in response to biased agonists, could have a significant impact in delineating precision medicine approaches and development of novel therapeutics.
Augustine V, Gokce SK, Lee S, Wang B, Davidson TJ, Reimann F, Gribble F, Deisseroth K, Lois C, Oka Y.
PMID: 29489747 | DOI: 10.1038/nature25488
Neural circuits for appetites are regulated by both homeostatic perturbations and ingestive behaviour. However, the circuit organization that integrates these internal and external stimuli is unclear. Here we show in mice that excitatory neural populations in the lamina terminalis form a hierarchical circuit architecture to regulate thirst. Among them, nitric oxide synthase-expressing neurons in the median preoptic nucleus (MnPO) are essential for the integration of signals from the thirst-driving neurons of the subfornical organ (SFO). Conversely, a distinct inhibitory circuit, involving MnPO GABAergic neurons that express glucagon-like peptide 1 receptor (GLP1R), is activated immediately upon drinking and monosynaptically inhibits SFO thirst neurons. These responses are induced by the ingestion of fluids but not solids, and are time-locked to the onset and offset of drinking. Furthermore, loss-of-function manipulations of GLP1R-expressing MnPO neurons lead to a polydipsic, overdrinking phenotype. These neurons therefore facilitate rapid satiety of thirst by monitoring real-time fluid ingestion. Our study reveals dynamic thirst circuits that integrate the homeostatic-instinctive requirement for fluids and the consequent drinking behaviour to maintain internal water balance.
Imbernon, M;Saponaro, C;Helms, HCC;Duquenne, M;Fernandois, D;Deligia, E;Denis, RGP;Chao, DHM;Rasika, S;Staels, B;Pattou, F;Pfrieger, FW;Brodin, B;Luquet, S;Bonner, C;Prevot, V;
PMID: 35716660 | DOI: 10.1016/j.cmet.2022.06.002
Liraglutide, an anti-diabetic drug and agonist of the glucagon-like peptide one receptor (GLP1R), has recently been approved to treat obesity in individuals with or without type 2 diabetes. Despite its extensive metabolic benefits, the mechanism and site of action of liraglutide remain unclear. Here, we demonstrate that liraglutide is shuttled to target cells in the mouse hypothalamus by specialized ependymoglial cells called tanycytes, bypassing the blood-brain barrier. Selectively silencing GLP1R in tanycytes or inhibiting tanycytic transcytosis by botulinum neurotoxin expression not only hampers liraglutide transport into the brain and its activation of target hypothalamic neurons, but also blocks its anti-obesity effects on food intake, body weight and fat mass, and fatty acid oxidation. Collectively, these striking data indicate that the liraglutide-induced activation of hypothalamic neurons and its downstream metabolic effects are mediated by its tanycytic transport into the mediobasal hypothalamus, strengthening the notion of tanycytes as key regulators of metabolic homeostasis.
Functionally distinct POMC-expressing neuron subpopulations in hypothalamus revealed by intersectional targeting
Biglari, N;Gaziano, I;Schumacher, J;Radermacher, J;Paeger, L;Klemm, P;Chen, W;Corneliussen, S;Wunderlich, CM;Sue, M;Vollmar, S;Klöckener, T;Sotelo-Hitschfeld, T;Abbasloo, A;Edenhofer, F;Reimann, F;Gribble, FM;Fenselau, H;Kloppenburg, P;Wunderlich, FT;Brüning, JC;
PMID: 34002087 | DOI: 10.1038/s41593-021-00854-0
Pro-opiomelanocortin (POMC)-expressing neurons in the arcuate nucleus of the hypothalamus represent key regulators of metabolic homeostasis. Electrophysiological and single-cell sequencing experiments have revealed a remarkable degree of heterogeneity of these neurons. However, the exact molecular basis and functional consequences of this heterogeneity have not yet been addressed. Here, we have developed new mouse models in which intersectional Cre/Dre-dependent recombination allowed for successful labeling, translational profiling and functional characterization of distinct POMC neurons expressing the leptin receptor (Lepr) and glucagon like peptide 1 receptor (Glp1r). Our experiments reveal that POMCLepr+ and POMCGlp1r+ neurons represent largely nonoverlapping subpopulations with distinct basic electrophysiological properties. They exhibit a specific anatomical distribution within the arcuate nucleus and differentially express receptors for energy-state communicating hormones and neurotransmitters. Finally, we identify a differential ability of these subpopulations to suppress feeding. Collectively, we reveal a notably distinct functional microarchitecture of critical metabolism-regulatory neurons.
Adams JM, Pei H, Sandoval DA, Seeley RJ, Chang RB, Liberles SD, Olson DP.
PMID: 29776968 | DOI: 10.2337/db17-1385
Glucagon-like peptide-1 receptor (GLP-1R) agonists are FDA-approved weight loss drugs. Despite their widespread use, the sites of action through which GLP-1R agonists (GLP1RAs) impact appetite and body weight are still not fully understood. Here, we determined whether GLP-1Rs in either GABAergic or glutamatergic neurons are necessary for the acute and chronic effects of the GLP1RA liraglutide on food intake, visceral illness, body weight and neural network activation. We found that mice lacking GLP-1Rs in vGAT-expressing GABAergic neurons responded identically to controls in all parameters measured, whereas deletion of GLP-1Rs in vGlut2-expressing glutamatergic neurons eliminated liraglutide-induced weight loss and visceral illness and severely attenuated its effects on feeding. Concomitantly, deletion of GLP-1Rs from glutamatergic neurons completely abolished the neural network activation observed after liraglutide administration. We conclude that liraglutide activates a dispersed but discrete neural network to mediate its physiological effects, and that these effects require GLP-1R expression on glutamatergic but not GABAergic neurons.
Zhao, Q;Yu, CD;Wang, R;Xu, QJ;Dai Pra, R;Zhang, L;Chang, RB;
PMID: 35296859 | DOI: 10.3760/cma.j.cn112151-20210719-00516
Interoception, the ability to timely and precisely sense changes inside the body, is critical for survival1-4. Vagal sensory neurons (VSNs) form an important body-to-brain connection, navigating visceral organs along the rostral-caudal axis of the body and crossing the surface-lumen axis of organs into appropriate tissue layers5,6. The brain can discriminate numerous body signals through VSNs, but the underlying coding strategy remains poorly understood. Here we show that VSNs code visceral organ, tissue layer and stimulus modality-three key features of an interoceptive signal-in different dimensions. Large-scale single-cell profiling of VSNs from seven major organs in mice using multiplexed projection barcodes reveals a 'visceral organ' dimension composed of differentially expressed gene modules that code organs along the body's rostral-caudal axis. We discover another 'tissue layer' dimension with gene modules that code the locations of VSN endings along the surface-lumen axis of organs. Using calcium-imaging-guided spatial transcriptomics, we show that VSNs are organized into functional units to sense similar stimuli across organs and tissue layers; this constitutes a third 'stimulus modality' dimension. The three independent feature-coding dimensions together specify many parallel VSN pathways in a combinatorial manner and facilitate the complex projection of VSNs in the brainstem. Our study highlights a multidimensional coding architecture of the mammalian vagal interoceptive system for effective signal communication.
Gut-brain communication by distinct sensory neurons differently controls feeding and glucose metabolism
Borgmann, D;Ciglieri, E;Biglari, N;Brandt, C;Cremer, AL;Backes, H;Tittgemeyer, M;Wunderlich, FT;Brüning, JC;Fenselau, H;
PMID: 34043943 | DOI: 10.1016/j.cmet.2021.05.002
Sensory neurons relay gut-derived signals to the brain, yet the molecular and functional organization of distinct populations remains unclear. Here, we employed intersectional genetic manipulations to probe the feeding and glucoregulatory function of distinct sensory neurons. We reconstruct the gut innervation patterns of numerous molecularly defined vagal and spinal afferents and identify their downstream brain targets. Bidirectional chemogenetic manipulations, coupled with behavioral and circuit mapping analysis, demonstrated that gut-innervating, glucagon-like peptide 1 receptor (GLP1R)-expressing vagal afferents relay anorexigenic signals to parabrachial nucleus neurons that control meal termination. Moreover, GLP1R vagal afferent activation improves glucose tolerance, and their inhibition elevates blood glucose levels independent of food intake. In contrast, gut-innervating, GPR65-expressing vagal afferent stimulation increases hepatic glucose production and activates parabrachial neurons that control normoglycemia, but they are dispensable for feeding regulation. Thus, distinct gut-innervating sensory neurons differentially control feeding and glucoregulatory neurocircuits and may provide specific targets for metabolic control.
Investigative Ophthalmology & Visual Science
Rey, AD;Lopez-Soriano, V;Corradi, Z;
* Alfredo Dueñas Rey Universitair Ziekenhuis Gent Centrum Medische Genetica Gent, Gent, Belgium Department of Biomolecular Medicine, Universiteit Gent Faculteit Geneeskunde en Gezondheidswetenschappen, Gent, Belgium * Víctor López-Soriano Universitair Ziekenhuis Gent Centrum Medische Genetica Gent, Gent, Belgium Department of Biomolecular Medicine, Universiteit Gent Faculteit Geneeskunde en Gezondheidswetenschappen, Gent, Belgium * Zelia Corradi Radboudumc Department of Human Genetics, Nijmegen, Gelderland, Netherlands * Claire-Marie Dhaenens Univ. Lille, Inserm, CHU Lille, U1172 - LilNCog - Lille Neuroscience & Cognition, Lille, France * Manon Bouckaert Universitair Ziekenhuis Gent Centrum Medische Genetica Gent, Gent, Belgium Department of Biomolecular Medicine, Universiteit Gent Faculteit Geneeskunde en Gezondheidswetenschappen, Gent, Belgium * Jasper Verwilt Department of Biomolecular Medicine, Universiteit Gent Faculteit Geneeskunde en Gezondheidswetenschappen, Gent, Belgium OncoRNALab, Cancer Research Institute Ghent, Ghent, Belgium * Avril M Watson Newcastle University Faculty of Medical Sciences, Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom * Majlinda Lako Newcastle University Faculty of Medical Sciences, Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom * Eva D’haene Universitair Ziekenhuis Gent Centrum Medische Genetica Gent, Gent, Belgium Department of Biomolecular Medicine, Universiteit Gent Faculteit Geneeskunde en Gezondheidswetenschappen, Gent, Belgium * Karla Alejandra Ruiz Ceja Telethon Institute of Genetics and Medicine, Napoli, Campania, Italy * Sandro Banfi Telethon Institute of Genetics and Medicine, Napoli, Campania, Italy * Miriam Bauwens Universitair Ziekenhuis Gent Centrum Medische Genetica Gent, Gent, Belgium Department of Biomolecular Medicine, Universiteit Gent Faculteit Geneeskunde en Gezondheidswetenschappen, Gent, Belgium * Frans P Cremers Radboudumc Department of Human Genetics, Nijmegen, Gelderland, Netherlands * Steve Lefever Universitair Ziekenhuis Gent Centrum Medische Genetica Gent, Gent, Belgium Department of Biomolecular Medicine, Universiteit Gent Faculteit Geneeskunde en Gezondheidswetenschappen, Gent, Belgium * Elfride De Baere Universitair Ziekenhuis Gent Centrum Medische Genetica Gent, Gent, Belgium Department of Biomolecular Medicine, Universiteit Gent Faculteit Geneeskunde en Gezondheidswetenschappen, Gent, Belgium * Frauke Coppieters Universitair Ziekenhuis Gent Centrum Medische Genetica Gent, Gent, Belgium Department of Biomolecular Medicine, Universiteit Gent Faculteit Geneeskunde en Gezondheidswetenschappen, Gent, Belgium
