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Fernández E, McCarthy CI, Cerviño RH, Rodríguez SS, Yaneff A, Hernández J, Garrido V, Di Rocco F, Raingo J. Functional alterations of two novel MC4R mutations found in Argentinian pediatric patients with early onset obesity. Mol Cell Endocrinol 2023; 559:111777. [PMID: 36210601 DOI: 10.1016/j.mce.2022.111777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 09/08/2022] [Accepted: 09/09/2022] [Indexed: 02/03/2023]
Abstract
Loss-of-function mutations in melanocortin-4 receptor (MC4R) are the most common cause of monogenic obesity, a severe type of early-onset obesity. Our aim was to determine the prevalence of MC4R mutations in a cohort of 97 Argentinian children with early-onset obesity. We found two novel mutations (p.V52E and p.G233S) and estimated a prevalence of 2.1%. We investigated the pathogenicity of mutations in HEK293T cells expressing wild-type or mutant MC4R and found that both mutants exhibited reduced plasma membrane expression and altered agonist-induced cAMP responses, with no changes in basal activity. Besides, MC4R G233S mutant demonstrated an altered agonist-dependent inhibition of voltage-gated calcium channels type 2.2. Results using a Gαs protein inhibitor suggest that the G233S mutation could be recruiting a different G-protein signaling pathway. The identification of new mutations in MC4R and characterization of their functional impact provide tools for the diagnosis and treatment of monogenic obesity.
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Affiliation(s)
- Estefanía Fernández
- Laboratorio de Genética Molecular, Instituto Multidisciplinario de Biología Celular (IMBICE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de La Plata (UNLP) y Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC-PBA), La Plata, Buenos Aires, Argentina.
| | - Clara Inés McCarthy
- Laboratorio de Electrofisiología, IMBICE, CONICET, UNLP y CIC-PBA, La Plata, Buenos Aires, Argentina.
| | - Ramiro Hector Cerviño
- Instituto de Investigaciones Farmacológicas (ININFA, UBA, CONICET), Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.
| | - Silvia Susana Rodríguez
- Laboratorio de Electrofisiología, IMBICE, CONICET, UNLP y CIC-PBA, La Plata, Buenos Aires, Argentina.
| | - Agustín Yaneff
- Instituto de Investigaciones Farmacológicas (ININFA, UBA, CONICET), Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.
| | - Julieta Hernández
- Servicio de Nutrición del Hospital de Niños "Sor María Ludovica" de La Plata, La Plata, Buenos Aires, Argentina.
| | - Verónica Garrido
- Servicio de Nutrición del Hospital de Niños "Sor María Ludovica" de La Plata, La Plata, Buenos Aires, Argentina.
| | - Florencia Di Rocco
- Laboratorio de Genética Molecular, Instituto Multidisciplinario de Biología Celular (IMBICE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de La Plata (UNLP) y Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC-PBA), La Plata, Buenos Aires, Argentina.
| | - Jesica Raingo
- Laboratorio de Electrofisiología, IMBICE, CONICET, UNLP y CIC-PBA, La Plata, Buenos Aires, Argentina.
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Portales AE, Mustafá ER, McCarthy CI, Cornejo MP, Couto PM, Gironacci MM, Caramelo JJ, Perelló M, Raingo J. ACE2 internalization induced by a SARS-CoV-2 recombinant protein is modulated by angiotensin II type 1 and bradykinin 2 receptors. Life Sci 2022; 293:120284. [PMID: 35038454 PMCID: PMC8758573 DOI: 10.1016/j.lfs.2021.120284] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/20/2021] [Accepted: 12/27/2021] [Indexed: 12/20/2022]
Abstract
AIMS Angiotensin-converting enzyme 2 (ACE2) is a key regulator of the renin-angiotensin system (RAS) recently identified as the membrane receptor for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Here we aim to study whether two receptors from RAS, the angiotensin receptor type 1 (AT1R) and the bradykinin 2 receptor (B2R) modulate ACE2 internalization induced by a recombinant receptor binding domain (RBD) of SARS-CoV-2 spike protein. Also, we investigated the impact of ACE2 coexpression on AT1R and B2R functionality. MATERIALS AND METHODS To study ACE2 internalization, we assessed the distribution of green fluorescent protein (GFP) signal in HEK293T cells coexpressing GFP-tagged ACE2 and AT1R, or B2R, or AT1R plus B2R in presence of RBD alone or in combination with AT1R or B2R ligands. To estimate ACE2 internalization, we classified GFP signal distribution as plasma membrane uniform GFP (PMU-GFP), plasma membrane clustered GFP (PMC-GFP) or internalized GFP and calculated its relative frequency. Additionally, we investigated the effect of ACE2 coexpression on AT1R and B2R inhibitory action on voltage-gated calcium channels (CaV2.2) currents by patch-clamp technique. KEY FINDINGS RBD induced ACE2-GFP internalization in a time-dependent manner. RBD-induced ACE2-GFP internalization was increased by angiotensin II and reduced by telmisartan in cells coexpressing AT1R. RBD-induced ACE2-GFP internalization was strongly inhibited by B2R co-expression. This effect was mildly modified by bradykinin and rescued by angiotensin II in presence of AT1R. ACE2 coexpression impacted on B2R- and AT1R-mediated inhibition of CaV2.2 currents. SIGNIFICANCE Our work contributes to understand the role of RAS modulators in the susceptibility to SARS-CoV-2 infection and severity of COVID-19.
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Affiliation(s)
- Andrea Estefanía Portales
- Laboratorio de Electrofisiología, Instituto Multidisciplinario de Biología Celular (IMBICE), Universidad Nacional de La Plata (UNLP), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC), Calle 526 1499-1579, B1906APM Tolosa, Buenos Aires, Argentina
| | - Emilio Román Mustafá
- Laboratorio de Electrofisiología, Instituto Multidisciplinario de Biología Celular (IMBICE), Universidad Nacional de La Plata (UNLP), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC), Calle 526 1499-1579, B1906APM Tolosa, Buenos Aires, Argentina
| | - Clara Inés McCarthy
- Laboratorio de Electrofisiología, Instituto Multidisciplinario de Biología Celular (IMBICE), Universidad Nacional de La Plata (UNLP), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC), Calle 526 1499-1579, B1906APM Tolosa, Buenos Aires, Argentina
| | - María Paula Cornejo
- Laboratorio de Neurofisiología, Instituto Multidisciplinario de Biología Celular (IMBICE), Universidad Nacional de La Plata (UNLP), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC), Calle 526 1499-1579, B1906APM Tolosa, Buenos Aires, Argentina
| | - Paula Monserrat Couto
- Fundación Instituto Leloir and Instituto de Investigaciones Bioquímicas de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Mariela Mercedes Gironacci
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB, UBA-CONICET), Argentina
| | - Julio Javier Caramelo
- Fundación Instituto Leloir and Instituto de Investigaciones Bioquímicas de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Mario Perelló
- Laboratorio de Neurofisiología, Instituto Multidisciplinario de Biología Celular (IMBICE), Universidad Nacional de La Plata (UNLP), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC), Calle 526 1499-1579, B1906APM Tolosa, Buenos Aires, Argentina
| | - Jesica Raingo
- Laboratorio de Electrofisiología, Instituto Multidisciplinario de Biología Celular (IMBICE), Universidad Nacional de La Plata (UNLP), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC), Calle 526 1499-1579, B1906APM Tolosa, Buenos Aires, Argentina..
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McCarthy CI, Chou-Freed C, Rodríguez SS, Yaneff A, Davio C, Raingo J. Constitutive activity of dopamine receptor type 1 (D1R) increases CaV2.2 currents in PFC neurons. J Gen Physiol 2021; 152:151624. [PMID: 32259196 PMCID: PMC7201881 DOI: 10.1085/jgp.201912492] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 02/14/2020] [Accepted: 03/12/2020] [Indexed: 01/19/2023] Open
Abstract
Alterations in dopamine receptor type 1 (D1R) density are associated with cognitive deficits of aging and schizophrenia. In the prefrontal cortex (PFC), D1R plays a critical role in the regulation of working memory, which is impaired in these cognitive deficit states, but the cellular events triggered by changes in D1R expression remain unknown. A previous report demonstrated that interaction between voltage-gated calcium channel type 2.2 (CaV2.2) and D1R stimulates CaV2.2 postsynaptic surface location in medial PFC pyramidal neurons. Here, we show that in addition to the occurrence of the physical receptor-channel interaction, constitutive D1R activity mediates up-regulation of functional CaV2.2 surface density. We performed patch-clamp experiments on transfected HEK293T cells and wild-type C57BL/6 mouse brain slices, as well as imaging experiments and cAMP measurements. We found that D1R coexpression led to ∼60% increase in CaV2.2 currents in HEK293T cells. This effect was occluded by preincubation with a D1/D5R inverse agonist, chlorpromazine, and by replacing D1R with a D1R mutant lacking constitutive activity. Moreover, D1R-induced increase in CaV2.2 currents required basally active Gs protein, as well as D1R-CaV2.2 interaction. In mice, intraperitoneal administration of chlorpromazine reduced native CaV currents’ sensitivity to ω-conotoxin-GVIA and their size by ∼49% in layer V/VI pyramidal neurons from medial PFC, indicating a selective effect on CaV2.2. Additionally, we found that reducing D1/D5R constitutive activity correlates with a decrease in the agonist-induced D1/D5R inhibitory effect on native CaV currents. Our results could be interpreted as a stimulatory effect of D1R constitutive activity on the number of CaV2.2 channels available for dopamine-mediated modulation. Our results contribute to the understanding of the physiological role of D1R constitutive activity and may explain the noncanonical postsynaptic distribution of functional CaV2.2 in PFC neurons.
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Affiliation(s)
- Clara Inés McCarthy
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology, Universidad Nacional de La Plata, Consejo de Investigaciones Científicas y Técnicas, Comisión de Investigaciones de la Provincia de Buenos Aires, Buenos Aires, Argentina
| | - Cambria Chou-Freed
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology, Universidad Nacional de La Plata, Consejo de Investigaciones Científicas y Técnicas, Comisión de Investigaciones de la Provincia de Buenos Aires, Buenos Aires, Argentina
| | - Silvia Susana Rodríguez
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology, Universidad Nacional de La Plata, Consejo de Investigaciones Científicas y Técnicas, Comisión de Investigaciones de la Provincia de Buenos Aires, Buenos Aires, Argentina
| | - Agustín Yaneff
- Instituto de Investigaciones Farmacológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Carlos Davio
- Instituto de Investigaciones Farmacológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Jesica Raingo
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology, Universidad Nacional de La Plata, Consejo de Investigaciones Científicas y Técnicas, Comisión de Investigaciones de la Provincia de Buenos Aires, Buenos Aires, Argentina
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MRAP2 Interaction with Melanocortin-4 Receptor in SnakeHead ( Channa argus). Biomolecules 2021; 11:biom11030481. [PMID: 33807040 PMCID: PMC8004712 DOI: 10.3390/biom11030481] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 03/11/2021] [Accepted: 03/19/2021] [Indexed: 02/06/2023] Open
Abstract
The melanocortin-4 receptor (MC4R) plays an important role in the regulation of food intake and energy expenditure. Melanocortin-2 receptor accessory protein 2 (MRAP2) modulates trafficking, ligand binding, and signaling of MC4R. The Northern snakehead (Channa argus) is an economically important freshwater fish native to East Asia. To explore potential interaction between snakehead MC4R and MRAP2, herein we cloned snakehead mc4r and mrap2. The snakehead mc4r consisted of a 984 bp open reading frame encoding a protein of 327 amino acids, while snakehead mrap2 contained a 693 bp open reading frame encoding a protein of 230 amino acids. Synteny analysis indicated that mc4r was highly conserved with similar gene arrangement, while mrap2 contained two isoforms in teleost with different gene orders. Snakehead mc4r was primarily expressed in the brain, whereas mrap2 was expressed in the brain and intestine. Snakehead mc4r and mrap2 expression was modulated by fasting and refeeding. Further pharmacological experiments showed that the cloned snakehead MC4R was functional, capable of binding to peptide agonists and increasing intracellular cAMP production in a dose-dependent manner. Snakehead MC4R exhibited high constitutive activity. MRAP2 significantly decreased basal and agonist-stimulated cAMP signaling. These findings suggest that snakehead MC4R might be involved in energy balance regulation by interacting with MRAP2. Further studies are needed to elucidate MC4R in regulating diverse physiological processes in snakehead.
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Rojo D, McCarthy C, Raingo J, Rubinstein M. Mouse models for V103I and I251L gain of function variants of the human MC4R display decreased adiposity but are not protected against a hypercaloric diet. Mol Metab 2020; 42:101077. [PMID: 32916307 PMCID: PMC7559519 DOI: 10.1016/j.molmet.2020.101077] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/20/2020] [Accepted: 09/06/2020] [Indexed: 11/17/2022] Open
Abstract
OBJECTIVE The melanocortin 4 receptor (MC4R) is a G protein-coupled receptor that plays major roles in the central control of energy balance. Loss-of-function mutations of MC4R constitute the most common monogenic cause of early-onset extreme obesity in humans, whereas gain-of-function mutations appear to be protective. In particular, two relatively frequent alleles carrying the non-synonymous coding mutations V103I or I251L are associated with lower risks of obesity and type-2 diabetes. Although V103I and I251L MC4Rs showed more efficient signalling in transfected cells, their specific effects in live animals remain unexplored. Here, we investigated whether the introduction of V103I and I251L mutations into the mouse MC4R leads to a lean phenotype and provides protection against an obesogenic diet. METHODS Using CRISPR/Cas9, we generated two novel strains of mice carrying single-nucleotide mutations into the mouse Mc4r which are identical to those present in V103I and I251L MCR4 human alleles, and studied their phenotypic outcomes in mice fed with normal chow or a high-fat diet. In particular, we measured body weight progression, food intake and adiposity. In addition, we analysed glucose homeostasis through glucose and insulin tolerance tests. RESULTS We found that homozygous V103I females displayed shorter longitudinal length and decreased abdominal white fat, whereas homozygous I251L females were also shorter and leaner due to decreased weight in all white fat pads examined. Homozygous Mc4rV103I/V103I and Mc4rI251L/I251L mice of both sexes showed improved glucose homeostasis when challenged in a glucose tolerance test, whereas Mc4rI251L/I251L females showed improved responses to insulin. Despite being leaner and metabolically more efficient, V103I and I251L mutants fed with a hypercaloric diet increased their fasting glucose levels and adiposity similar to their wild-type littermates. CONCLUSIONS Our results demonstrate that mice carrying V103I and I251L MC4R mutations displayed gain-of-function phenotypes that were more evident in females. However, hypermorphic MC4R mutants were as susceptible as their control littermates to the obesogenic and diabetogenic effects elicited by a long-term hypercaloric diet, highlighting the importance of healthy feeding habits even under favourable genetic conditions.
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Affiliation(s)
- Daniela Rojo
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas, 1428 Buenos Aires, Argentina
| | - Clara McCarthy
- Instituto Multidisciplinario de Biología Celular, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad de La Plata and Comisión de Investigaciones de la Provincia de Buenos Aires, La Plata, Province of Buenos Aires, Argentina
| | - Jesica Raingo
- Instituto Multidisciplinario de Biología Celular, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad de La Plata and Comisión de Investigaciones de la Provincia de Buenos Aires, La Plata, Province of Buenos Aires, Argentina
| | - Marcelo Rubinstein
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas, 1428 Buenos Aires, Argentina; Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, 1428 Buenos Aires, Argentina; Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48105, USA.
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Comeras LB, Herzog H, Tasan RO. Neuropeptides at the crossroad of fear and hunger: a special focus on neuropeptide Y. Ann N Y Acad Sci 2019; 1455:59-80. [PMID: 31271235 PMCID: PMC6899945 DOI: 10.1111/nyas.14179] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 05/15/2019] [Accepted: 06/03/2019] [Indexed: 12/11/2022]
Abstract
Survival in a natural environment forces an individual into constantly adapting purposive behavior. Specified interoceptive neurons monitor metabolic and physiological balance and activate dedicated brain circuits to satisfy essential needs, such as hunger, thirst, thermoregulation, fear, or anxiety. Neuropeptides are multifaceted, central components within such life‐sustaining programs. For instance, nutritional depletion results in a drop in glucose levels, release of hormones, and activation of hypothalamic and brainstem neurons. These neurons, in turn, release several neuropeptides that increase food‐seeking behavior and promote food intake. Similarly, internal and external threats activate neuronal pathways of avoidance and defensive behavior. Interestingly, specific nuclei of the hypothalamus and extended amygdala are activated by both hunger and fear. Here, we introduce the relevant neuropeptides and describe their function in feeding and emotional‐affective behaviors. We further highlight specific pathways and microcircuits, where neuropeptides may interact to identify prevailing homeostatic needs and direct respective compensatory behaviors. A specific focus will be on neuropeptide Y, since it is known for its pivotal role in metabolic and emotional pathways. We hypothesize that the orexigenic and anorexigenic properties of specific neuropeptides are related to their ability to inhibit fear and anxiety.
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Affiliation(s)
- Lucas B Comeras
- Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria
| | - Herbert Herzog
- Neuroscience Division, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Ramon O Tasan
- Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria
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Baldini G, Phelan KD. The melanocortin pathway and control of appetite-progress and therapeutic implications. J Endocrinol 2019; 241:R1-R33. [PMID: 30812013 PMCID: PMC6500576 DOI: 10.1530/joe-18-0596] [Citation(s) in RCA: 125] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 01/22/2019] [Indexed: 12/19/2022]
Abstract
The initial discovery that ob/ob mice become obese because of a recessive mutation of the leptin gene has been crucial to discover the melanocortin pathway to control appetite. In the melanocortin pathway, the fed state is signaled by abundance of circulating hormones such as leptin and insulin, which bind to receptors expressed at the surface of pro-opiomelanocortin (POMC) neurons to promote processing of POMC to the mature hormone α-melanocyte-stimulating hormone (α-MSH). The α-MSH released by POMC neurons then signals to decrease energy intake by binding to melanocortin-4 receptor (MC4R) expressed by MC4R neurons to the paraventricular nucleus (PVN). Conversely, in the 'starved state' activity of agouti-related neuropeptide (AgRP) and of neuropeptide Y (NPY)-expressing neurons is increased by decreased levels of circulating leptin and insulin and by the orexigenic hormone ghrelin to promote food intake. This initial understanding of the melanocortin pathway has recently been implemented by the description of the complex neuronal circuit that controls the activity of POMC, AgRP/NPY and MC4R neurons and downstream signaling by these neurons. This review summarizes the progress done on the melanocortin pathway and describes how obesity alters this pathway to disrupt energy homeostasis. We also describe progress on how leptin and insulin receptors signal in POMC neurons, how MC4R signals and how altered expression and traffic of MC4R change the acute signaling and desensitization properties of the receptor. We also describe how the discovery of the melanocortin pathway has led to the use of melanocortin agonists to treat obesity derived from genetic disorders.
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Affiliation(s)
- Giulia Baldini
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Kevin D. Phelan
- Department of Neurobiology & Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
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Zhang Y, Jiang D, Li H, Sun Y, Jiang X, Gong S, Qian Z, Tao J. Melanocortin type 4 receptor-mediated inhibition of A-type K + current enhances sensory neuronal excitability and mechanical pain sensitivity in rats. J Biol Chem 2019; 294:5496-5507. [PMID: 30745360 DOI: 10.1074/jbc.ra118.006894] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 02/07/2019] [Indexed: 12/28/2022] Open
Abstract
α-Melanocyte-stimulating hormone (α-MSH) has been shown to be involved in nociception, but the underlying molecular mechanisms remain largely unknown. In this study, we report that α-MSH suppresses the transient outward A-type K+ current (I A) in trigeminal ganglion (TG) neurons and thereby modulates neuronal excitability and peripheral pain sensitivity in rats. Exposing small-diameter TG neurons to α-MSH concentration-dependently decreased I A This α-MSH-induced I A decrease was dependent on the melanocortin type 4 receptor (MC4R) and associated with a hyperpolarizing shift in the voltage dependence of A-type K+ channel inactivation. Chemical inhibition of phosphatidylinositol 3-kinase (PI3K) with wortmannin or of class I PI3Ks with the selective inhibitor CH5132799 prevented the MC4R-mediated I A response. Blocking Gi/o-protein signaling with pertussis toxin or by dialysis of TG neurons with the Gβγ-blocking synthetic peptide QEHA abolished the α-MSH-mediated decrease in I A Further, α-MSH increased the expression levels of phospho-p38 mitogen-activated protein kinase, and pharmacological or genetic inhibition of p38α abrogated the α-MSH-induced I A response. Additionally, α-MSH significantly increased the action potential firing rate of TG neurons and increased the sensitivity of rats to mechanical stimuli applied to the buccal pad area, and both effects were abrogated by I A blockade. Taken together, our findings suggest that α-MSH suppresses I A by activating MC4R, which is coupled sequentially to the Gβγ complex of the Gi/o-protein and downstream class I PI3K-dependent p38α signaling, thereby increasing TG neuronal excitability and mechanical pain sensitivity in rats.
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Affiliation(s)
- Yuan Zhang
- From the Department of Geriatrics, the Second Affiliated Hospital of Soochow University, Suzhou 215004, China.,the Department of Physiology and Neurobiology and Centre for Ion Channelopathy, Medical College of Soochow University, Suzhou 215123, China
| | - Dongsheng Jiang
- the Department of Physiology and Neurobiology and Centre for Ion Channelopathy, Medical College of Soochow University, Suzhou 215123, China.,the Comprehensive Pneumology Center, Helmholtz Zentrum München, Munich 81377, Germany, and
| | - Hua Li
- the National Shanghai Center for New Drug Safety Evaluation and Research, Shanghai 201203, China
| | - Yufang Sun
- the Department of Physiology and Neurobiology and Centre for Ion Channelopathy, Medical College of Soochow University, Suzhou 215123, China
| | - Xinghong Jiang
- the Department of Physiology and Neurobiology and Centre for Ion Channelopathy, Medical College of Soochow University, Suzhou 215123, China
| | - Shan Gong
- the Department of Physiology and Neurobiology and Centre for Ion Channelopathy, Medical College of Soochow University, Suzhou 215123, China
| | - Zhiyuan Qian
- From the Department of Geriatrics, the Second Affiliated Hospital of Soochow University, Suzhou 215004, China,
| | - Jin Tao
- the Department of Physiology and Neurobiology and Centre for Ion Channelopathy, Medical College of Soochow University, Suzhou 215123, China, .,the Jiangsu Key Laboratory of Neuropsychiatric Diseases, Soochow University, Suzhou 215123, China
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G-protein coupled receptors Mc4r and Drd1a can serve as surrogate odorant receptors in mouse olfactory sensory neurons. Mol Cell Neurosci 2018; 88:138-147. [PMID: 29407371 DOI: 10.1016/j.mcn.2018.01.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 01/26/2018] [Accepted: 01/29/2018] [Indexed: 01/11/2023] Open
Abstract
In the mouse, most mature olfactory sensory neurons (OSNs) express one allele of one gene from the repertoire of ~1100 odorant receptor (OR) genes, which encode G-protein coupled receptors (GPCRs). Axons of OSNs that express a given OR coalesce into homogeneous glomeruli, which reside at conserved positions in the olfactory bulb. ORs are intimately involved in ensuring the expression of one OR per OSN and the coalescence of OSN axons into glomeruli. But the mechanisms whereby ORs accomplish these diverse functions remain poorly understood. An experimental approach that has been informative is to substitute an OR genetically with another GPCR that is normally not expressed in OSNs, in order to determine in which aspects this GPCR can serve as surrogate OR in mouse OSNs. Thus far only the β2-adrenergic receptor (β2AR, Ardb2) has been shown to be able to serve as surrogate OR in OSNs; the β2AR could substitute for the M71 OR in all aspects examined. Can other non-olfactory GPCRs function equally well as surrogate ORs in OSNs? Here, we have generated and characterized two novel gene-targeted mouse strains in which the mouse melanocortin 4 receptor (Mc4r) or the mouse dopamine receptor D1 (Drd1a) is coexpressed with tauGFP in OSNs that express the OR locus M71. These alleles and strains are abbreviated as Mc4r → M71-GFP and Drd1a → M71-GFP. We detected strong Mc4r or Drd1a immunoreactivity in axons and dendritic knobs and cilia of OSNs that express Mc4r or Drd1a from the M71 locus. These OSNs responded physiologically to cognate agonists for Mc4r (Ro27-3225) or Drd1a (SKF81297), and not to the M71 ligand acetophenone. Axons of OSNs expressing Mc4r → M71-GFP coalesced into glomeruli. Axons of OSNs expressing Drd1a → M71-GFP converged onto restricted areas of the olfactory bulb but did not coalesce into glomeruli. Thus, OR functions in OSNs can be substituted by Mc4r or Drd1a, but not as well as by β2AR. We attribute the weak performance of Drd1a as surrogate OR to poor OSN maturation.
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Paiva L, Sabatier N, Leng G, Ludwig M. Effect of Melanotan-II on Brain Fos Immunoreactivity and Oxytocin Neuronal Activity and Secretion in Rats. J Neuroendocrinol 2017; 29. [PMID: 28009464 DOI: 10.1111/jne.12454] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 12/09/2016] [Accepted: 12/20/2016] [Indexed: 12/13/2022]
Abstract
Melanocortins stimulate the central oxytocin systems that are involved in regulating social behaviours. Alterations in central oxytocin have been linked to neurological disorders such as autism, and melanocortins have been proposed for therapeutic treatment. In the present study, we investigated how systemic administration of melanotan-II (MT-II), a melanocortin agonist, affects oxytocin neuronal activity and secretion in rats. The results obtained show that i.v., but not intranasal, administration of MT-II markedly induced Fos expression in magnocellular neurones of the supraoptic (SON) and paraventricular nuclei (PVN) of the hypothalamus, and this response was attenuated by prior i.c.v. administration of the melanocortin antagonist, SHU-9119. Electrophysiological recordings from identified magnocellular neurones of the SON showed that i.v. administration of MT-II increased the firing rate in oxytocin neurones but did not trigger somatodendritic oxytocin release within the SON as measured by microdialysis. Our data suggest that, after i.v., but not intranasal, administration of MT-II, the activity of magnocellular neurones of the SON is increased. Because previous studies showed that SON oxytocin neurones are inhibited in response to direct application of melanocortin agonists, the actions of i.v. MT-II are likely to be mediated at least partly indirectly, possibly by activation of inputs from the caudal brainstem, where MT-II also increased Fos expression.
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Affiliation(s)
- L Paiva
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | - N Sabatier
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | - G Leng
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | - M Ludwig
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
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11
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Agosti F, Cordisco Gonzalez S, Martinez Damonte V, Tolosa MJ, Di Siervi N, Schioth HB, Davio C, Perello M, Raingo J. Melanocortin 4 receptor constitutive activity inhibits L-type voltage-gated calcium channels in neurons. Neuroscience 2017; 346:102-112. [PMID: 28093215 DOI: 10.1016/j.neuroscience.2017.01.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 12/16/2016] [Accepted: 01/05/2017] [Indexed: 11/19/2022]
Abstract
The melanocortin 4 receptor (MC4R) is a G protein-coupled receptor (GPCR) that is expressed in several brain nuclei playing a crucial role in the regulation of energy balance controlling the homeostasis of the organism. It displays both agonist-evoked and constitutive activity, and moreover, it can couple to different G proteins. Most of the research on MC4R has been focused on agonist-induced activity, while the molecular and cellular basis of MC4R constitutive activity remains scarcely studied. We have previously shown that neuronal N-type voltage-gated calcium channels (CaV2.2) are inhibited by MC4R agonist-dependent activation, while the CaV subtypes that carry L- and P/Q-type current are not. Here, we tested the hypothesis that MC4R constitutive activity can affect CaV, with focus on the channel subtypes that can control transcriptional activity coupled to depolarization (L-type, CaV1.2/1.3) and neurotransmitter release (N- and P/Q-type, CaV2.2 and CaV2.1). We found that MC4R constitutive activity inhibits specifically CaV1.2/1.3 and CaV2.1 subtypes of CaV. We also explored the signaling pathways mediating this inhibition, and thus propose that agonist-dependent and basal MC4R activation modes signal differentially through Gs and Gi/o pathways to impact on different CaV subtypes. In addition, we found that chronic incubation with MC4R endogenous inverse agonist, agouti and agouti-related peptide (AgRP), occludes CaV inhibition in a cell line and in amygdaloid complex cultured neurons as well. Thus, we define new mechanisms of control of the main mediators of depolarization-induced calcium entry into neurons by a GPCR that displays constitutive activity.
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Affiliation(s)
- F Agosti
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE) Universidad de La Plata-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comision de Investigaciones de la Provincia de buenos Aires (CIC), La Plata, Buenos Aires, Argentina
| | - S Cordisco Gonzalez
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE) Universidad de La Plata-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comision de Investigaciones de la Provincia de buenos Aires (CIC), La Plata, Buenos Aires, Argentina
| | - V Martinez Damonte
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE) Universidad de La Plata-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comision de Investigaciones de la Provincia de buenos Aires (CIC), La Plata, Buenos Aires, Argentina
| | - M J Tolosa
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE) Universidad de La Plata-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comision de Investigaciones de la Provincia de buenos Aires (CIC), La Plata, Buenos Aires, Argentina
| | - N Di Siervi
- Instituto de Investigaciones Farmacológicas, ININFA, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, Buenos Aires, Argentina
| | - H B Schioth
- Department of Neuroscience, Functional Pharmacology, Uppsala University, Uppsala, Sweden
| | - C Davio
- Instituto de Investigaciones Farmacológicas, ININFA, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, Buenos Aires, Argentina
| | - M Perello
- Neurophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE) Universidad de La Plata-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comision de Investigaciones de la Provincia de buenos Aires (CIC), La Plata, Buenos Aires, Argentina
| | - J Raingo
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE) Universidad de La Plata-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comision de Investigaciones de la Provincia de buenos Aires (CIC), La Plata, Buenos Aires, Argentina
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12
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Ladyman SR, Augustine RA, Scherf E, Phillipps HR, Brown CH, Grattan DR. Attenuated hypothalamic responses to α-melanocyte stimulating hormone during pregnancy in the rat. J Physiol 2016; 594:1087-101. [PMID: 26613967 DOI: 10.1113/jp271605] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 11/23/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Increased appetite and weight gain occurs during pregnancy, associated with development of leptin resistance, and satiety responses to the anorectic peptide α-melanocyte stimulating hormone (α-MSH) are suppressed. This study investigated hypothalamic responses to α-MSH during pregnancy, using c-fos expression in specific hypothalamic nuclei as a marker of neuronal signalling, and in vivo electrophysiology in supraoptic nucleus (SON) oxytocin neurons, as a representative α-MSH-responsive neuronal population that shows a well-characterised α-MSH-induced inhibition of firing. While icv injection of α-MSH significantly increased the number of c-fos-positive cells in the paraventricular, supraoptic, arcuate and ventromedial hypothalamic nuclei in non-pregnant rats, this response was suppressed in pregnant rats. Similarly, SON oxytocin neurons in pregnant rats did not demonstrate characteristic α-MSH-induced inhibition of firing that was observed in non-pregnant animals. Given the known functions of α-MSH in the hypothalamus, the attenuated responses are likely to facilitate adaptive changes in appetite regulation and oxytocin secretion during pregnancy. ABSTRACT During pregnancy, a state of positive energy balance develops to support the growing fetus and to deposit fat in preparation for the subsequent metabolic demands of lactation. As part of this maternal adaptation, the satiety response to the anorectic peptide α-melanocyte stimulating hormone (α-MSH) is suppressed. To investigate whether pregnancy is associated with changes in the response of hypothalamic α-MSH target neurons, non-pregnant and pregnant rats were treated with α-MSH or vehicle and c-fos expression in hypothalamic nuclei was then examined. Furthermore, the firing rate of supraoptic nucleus (SON) oxytocin neurons, a known α-MSH responsive neuronal population, was examined in non-pregnant and pregnant rats following α-MSH treatment. Intracerebroventricular injection of α-MSH significantly increased the number of c-fos-positive cells in the paraventricular, arcuate and ventromedial hypothalamic nuclei in non-pregnant rats, but no significant increase was observed in any of these regions in pregnant rats. In the SON, α-MSH did induce expression of c-fos during pregnancy, but this was significantly reduced compared to that observed in the non-pregnant group. Furthermore, during pregnancy, SON oxytocin neurons did not demonstrate the characteristic α-MSH-induced inhibition of firing rate that was observed in non-pregnant animals. Melanocortin receptor mRNA levels during pregnancy were similar to non-pregnant animals, suggesting that receptor down-regulation is unlikely to be a mechanism underlying the attenuated responses to α-MSH during pregnancy. Given the known functions of α-MSH in the hypothalamus, the attenuated responses will facilitate adaptive changes in appetite regulation and oxytocin secretion during pregnancy.
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Affiliation(s)
- S R Ladyman
- Department of Anatomy and Centre for Neuroendocrinology, School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - R A Augustine
- Department of Physiology and Centre for Neuroendocrinology, School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - E Scherf
- Department of Anatomy and Centre for Neuroendocrinology, School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - H R Phillipps
- Department of Anatomy and Centre for Neuroendocrinology, School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - C H Brown
- Department of Physiology and Centre for Neuroendocrinology, School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - D R Grattan
- Department of Anatomy and Centre for Neuroendocrinology, School of Medical Sciences, University of Otago, Dunedin, New Zealand
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Roseberry AG, Stuhrman K, Dunigan AI. Regulation of the mesocorticolimbic and mesostriatal dopamine systems by α-melanocyte stimulating hormone and agouti-related protein. Neurosci Biobehav Rev 2015; 56:15-25. [DOI: 10.1016/j.neubiorev.2015.06.020] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 06/15/2015] [Accepted: 06/21/2015] [Indexed: 11/24/2022]
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López Soto EJ, Agosti F, Cabral A, Mustafa ER, Damonte VM, Gandini MA, Rodríguez S, Castrogiovanni D, Felix R, Perelló M, Raingo J. Constitutive and ghrelin-dependent GHSR1a activation impairs CaV2.1 and CaV2.2 currents in hypothalamic neurons. ACTA ACUST UNITED AC 2015; 146:205-19. [PMID: 26283199 PMCID: PMC4555474 DOI: 10.1085/jgp.201511383] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 07/13/2015] [Indexed: 12/22/2022]
Abstract
Constitutive and ligand-dependent GHSR1a activity attenuates CaV2 current and hypothalamic GABA release through distinct mechanisms and signaling pathways. The growth hormone secretagogue receptor type 1a (GHSR1a) has the highest known constitutive activity of any G protein–coupled receptor (GPCR). GHSR1a mediates the action of the hormone ghrelin, and its activation increases transcriptional and electrical activity in hypothalamic neurons. Although GHSR1a is present at GABAergic presynaptic terminals, its effect on neurotransmitter release remains unclear. The activities of the voltage-gated calcium channels, CaV2.1 and CaV2.2, which mediate neurotransmitter release at presynaptic terminals, are modulated by many GPCRs. Here, we show that both constitutive and agonist-dependent GHSR1a activity elicit a strong impairment of CaV2.1 and CaV2.2 currents in rat and mouse hypothalamic neurons and in a heterologous expression system. Constitutive GHSR1a activity reduces CaV2 currents by a Gi/o-dependent mechanism that involves persistent reduction in channel density at the plasma membrane, whereas ghrelin-dependent GHSR1a inhibition is reversible and involves altered CaV2 gating via a Gq-dependent pathway. Thus, GHSR1a differentially inhibits CaV2 channels by Gi/o or Gq protein pathways depending on its mode of activation. Moreover, we present evidence suggesting that GHSR1a-mediated inhibition of CaV2 attenuates GABA release in hypothalamic neurons, a mechanism that could contribute to neuronal activation through the disinhibition of postsynaptic neurons.
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Affiliation(s)
- Eduardo Javier López Soto
- Laboratory of Electrophysiology and Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE), B1904CMA La Plata, Buenos Aires, Argentina
| | - Francina Agosti
- Laboratory of Electrophysiology and Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE), B1904CMA La Plata, Buenos Aires, Argentina
| | - Agustina Cabral
- Laboratory of Electrophysiology and Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE), B1904CMA La Plata, Buenos Aires, Argentina
| | - Emilio Roman Mustafa
- Laboratory of Electrophysiology and Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE), B1904CMA La Plata, Buenos Aires, Argentina
| | - Valentina Martínez Damonte
- Laboratory of Electrophysiology and Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE), B1904CMA La Plata, Buenos Aires, Argentina
| | - Maria Alejandra Gandini
- Department of Cell Biology, Center for Research and Advanced Studies of the National Polytechnic Institute, 07000 México D.F., México
| | - Silvia Rodríguez
- Laboratory of Electrophysiology and Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE), B1904CMA La Plata, Buenos Aires, Argentina
| | - Daniel Castrogiovanni
- Laboratory of Electrophysiology and Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE), B1904CMA La Plata, Buenos Aires, Argentina Laboratory of Electrophysiology and Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE), B1904CMA La Plata, Buenos Aires, Argentina
| | - Ricardo Felix
- Department of Cell Biology, Center for Research and Advanced Studies of the National Polytechnic Institute, 07000 México D.F., México
| | - Mario Perelló
- Laboratory of Electrophysiology and Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE), B1904CMA La Plata, Buenos Aires, Argentina
| | - Jesica Raingo
- Laboratory of Electrophysiology and Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE), B1904CMA La Plata, Buenos Aires, Argentina
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Neuroanatomical and functional characterization of CRF neurons of the amygdala using a novel transgenic mouse model. Neuroscience 2015; 289:153-65. [PMID: 25595987 DOI: 10.1016/j.neuroscience.2015.01.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Revised: 12/24/2014] [Accepted: 01/06/2015] [Indexed: 12/20/2022]
Abstract
The corticotropin-releasing factor (CRF)-producing neurons of the amygdala have been implicated in behavioral and physiological responses associated with fear, anxiety, stress, food intake and reward. To overcome the difficulties in identifying CRF neurons within the amygdala, a novel transgenic mouse line, in which the humanized recombinant Renilla reniformis green fluorescent protein (hrGFP) is under the control of the CRF promoter (CRF-hrGFP mice), was developed. First, the CRF-hrGFP mouse model was validated and the localization of CRF neurons within the amygdala was systematically mapped. Amygdalar hrGFP-expressing neurons were located primarily in the interstitial nucleus of the posterior limb of the anterior commissure, but also present in the central amygdala. Secondly, the marker of neuronal activation c-Fos was used to explore the response of amygdalar CRF neurons in CRF-hrGFP mice under different experimental paradigms. C-Fos induction was observed in CRF neurons of CRF-hrGFP mice exposed to an acute social defeat stress event, a fasting/refeeding paradigm or lipopolysaccharide (LPS) administration. In contrast, no c-Fos induction was detected in CRF neurons of CRF-hrGFP mice exposed to restraint stress, forced swimming test, 48-h fasting, acute high-fat diet (HFD) consumption, intermittent HFD consumption, ad libitum HFD consumption, HFD withdrawal, conditioned HFD aversion, ghrelin administration or melanocortin 4 receptor agonist administration. Thus, this study fully characterizes the distribution of amygdala CRF neurons in mice and suggests that they are involved in some, but not all, stress or food intake-related behaviors recruiting the amygdala.
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