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Cui Y, Ma X, Wei J, Chen C, Shakir N, Guirram H, Dai Z, Anderson T, Ferguson D, Qiu S. MET receptor tyrosine kinase promotes the generation of functional synapses in adult cortical circuits. Neural Regen Res 2025; 20:1431-1444. [PMID: 39075910 DOI: 10.4103/nrr.nrr-d-23-01471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 04/20/2024] [Indexed: 07/31/2024] Open
Abstract
JOURNAL/nrgr/04.03/01300535-202505000-00026/figure1/v/2024-07-28T173839Z/r/image-tiff Loss of synapse and functional connectivity in brain circuits is associated with aging and neurodegeneration, however, few molecular mechanisms are known to intrinsically promote synaptogenesis or enhance synapse function. We have previously shown that MET receptor tyrosine kinase in the developing cortical circuits promotes dendritic growth and dendritic spine morphogenesis. To investigate whether enhancing MET in adult cortex has synapse regenerating potential, we created a knockin mouse line, in which the human MET gene expression and signaling can be turned on in adult (10-12 months) cortical neurons through doxycycline-containing chow. We found that similar to the developing brain, turning on MET signaling in the adult cortex activates small GTPases and increases spine density in prefrontal projection neurons. These findings are further corroborated by increased synaptic activity and transient generation of immature silent synapses. Prolonged MET signaling resulted in an increased α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/N-methyl-D-aspartate (AMPA/NMDA) receptor current ratio, indicative of enhanced synaptic function and connectivity. Our data reveal that enhancing MET signaling could be an interventional approach to promote synaptogenesis and preserve functional connectivity in the adult brain. These findings may have implications for regenerative therapy in aging and neurodegeneration conditions.
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Affiliation(s)
- Yuehua Cui
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Xiaokuang Ma
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Jing Wei
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Chang Chen
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Neha Shakir
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Hitesch Guirram
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Zhiyu Dai
- Department of Medicine, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Trent Anderson
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Deveroux Ferguson
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Shenfeng Qiu
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
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2
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Lanjewar AL, Levitt P, Eagleson KL. Developmental and molecular contributions to contextual fear memory emergence in mice. Neuropsychopharmacology 2024; 49:1392-1401. [PMID: 38438594 PMCID: PMC11251045 DOI: 10.1038/s41386-024-01835-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 02/02/2024] [Accepted: 02/15/2024] [Indexed: 03/06/2024]
Abstract
Cognitive impairment is a common phenotype of neurodevelopmental disorders, but how these deficits arise remains elusive. Determining the onset of discrete cognitive capabilities facilitates studies in probing mechanisms underlying their emergence. The present study analyzed the emergence of contextual fear memory persistence (7-day memory retention) and remote memory (30-day memory retention). There was a rapid transition from postnatal day (P) 20 to P21, in which memory persistence emerged in C57Bl/6 J male and female mice. Remote memory was present at P23, but expression was not robust compared to pubertal and adult mice. Previous studies reported that following deletion of the MET receptor tyrosine kinase (MET), there are fear memory deficits in adult mice and the timing of critical period plasticity is altered in the developing visual cortex, positioning MET as a regulator for onset of contextual fear memory. Sustaining Met past the normal window of peak cortical expression or deleting Met, however, did not alter the timing of emergence of persistence or remote memory capabilities during development. Fear memory in young adults, however, was disrupted. Remarkably, compared to homecage controls, the number of FOS-expressing infragranular neurons in medial prefrontal cortex (mPFC) did not increase from contextual memory formation recall of fear conditioning at P35 but exhibited enhanced activation at P90 in male and female mice. Additionally, MET-expressing neurons were preferentially recruited at P90 compared to P35 during fear memory expression. The studies demonstrate a developmental profile of contextual fear memory capabilities. Further, developmental disruption of Met leads to a delayed functional deficit that arises in young adulthood, correlated with an increase of mPFC neuron activation during fear memory recall.
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Affiliation(s)
- Alexandra L Lanjewar
- Program in Developmental Neuroscience and Neurogenetics, Children's Hospital Los Angeles, The Saban Research Institute, Los Angeles, CA, USA.
- Department of Pediatrics, Keck School of Medicine of University of Southern California, Los Angeles, CA, USA.
| | - Pat Levitt
- Program in Developmental Neuroscience and Neurogenetics, Children's Hospital Los Angeles, The Saban Research Institute, Los Angeles, CA, USA
- Department of Pediatrics, Keck School of Medicine of University of Southern California, Los Angeles, CA, USA
| | - Kathie L Eagleson
- Program in Developmental Neuroscience and Neurogenetics, Children's Hospital Los Angeles, The Saban Research Institute, Los Angeles, CA, USA
- Department of Pediatrics, Keck School of Medicine of University of Southern California, Los Angeles, CA, USA
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3
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Tarvestad-Laise KE, Ceresa BP. Modulating Growth Factor Receptor Signaling to Promote Corneal Epithelial Homeostasis. Cells 2023; 12:2730. [PMID: 38067157 PMCID: PMC10706396 DOI: 10.3390/cells12232730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 11/20/2023] [Accepted: 11/27/2023] [Indexed: 12/18/2023] Open
Abstract
The corneal epithelium is the first anatomical barrier between the environment and the cornea; it is critical for proper light refraction onto the retina and prevents pathogens (e.g., bacteria, viruses) from entering the immune-privileged eye. Trauma to the highly innervated corneal epithelium is extremely painful and if not resolved quickly or properly, can lead to infection and ultimately blindness. The healthy eye produces its own growth factors and is continuously bathed in tear fluid that contains these proteins and other nutrients to maintain the rapid turnover and homeostasis of the ocular surface. In this article, we review the roles of growth factors in corneal epithelial homeostasis and regeneration and some of the limitations to their use therapeutically.
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Affiliation(s)
- Kate E. Tarvestad-Laise
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY 40202, USA
| | - Brian P. Ceresa
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY 40202, USA
- Department of Ophthalmology and Vision Sciences, University of Louisville, Louisville, KY 40202, USA
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4
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Eagleson KL, Levitt P. Alterations in the Proteome of Developing Neocortical Synaptosomes in the Absence of MET Signaling Revealed by Comparative Proteomics. Dev Neurosci 2023; 45:126-138. [PMID: 36882009 PMCID: PMC10239366 DOI: 10.1159/000529981] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 02/28/2023] [Indexed: 03/09/2023] Open
Abstract
Alterations in the expression of genes encoding proteins involved in synapse formation, maturation, and function are a hallmark of many neurodevelopmental and psychiatric disorders. For example, there is reduced neocortical expression of the MET receptor tyrosine kinase (MET) transcript and protein in Autism Spectrum Disorder (ASD) and Rett syndrome. Preclinical in vivo and in vitro models manipulating MET signaling reveal that the receptor modulates excitatory synapse development and maturation in select forebrain circuits. The molecular adaptations underlying the altered synaptic development remain unknown. We performed a comparative mass spectrometry analysis of synaptosomes generated from the neocortex of wild type and Met null mice during the peak of synaptogenesis (postnatal day 14; data are available from ProteomeXchange with identifier PXD033204). The analyses revealed broad disruption of the developing synaptic proteome in the absence of MET, consistent with the localization of MET protein in pre- and postsynaptic compartments, including proteins associated with the neocortical synaptic MET interactome and those encoded by syndromic and ASD risk genes. In addition to an overrepresentation of altered proteins associated with the SNARE complex, multiple proteins in the ubiquitin-proteasome system and associated with the synaptic vesicle, as well as proteins that regulate actin filament organization and synaptic vesicle exocytosis/endocytosis, were disrupted. Taken together, the proteomic changes are consistent with structural and functional changes observed following alterations in MET signaling. We hypothesize that the molecular adaptations following Met deletion may reflect a general mechanism that produces circuit-specific molecular changes due to loss or reduction of synaptic signaling proteins.
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Affiliation(s)
- Kathie L Eagleson
- Department of Pediatrics and Neurogenetics Program, The Saban Research Institute, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
- Developmental Neuroscience and Neurogenetics Program, The Saban Research Institute, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Pat Levitt
- Department of Pediatrics and Neurogenetics Program, The Saban Research Institute, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, California, USA,
- Developmental Neuroscience and Neurogenetics Program, The Saban Research Institute, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, California, USA,
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5
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Hedou E, Douceau S, Chevilley A, Varangot A, Thiebaut AM, Triniac H, Bardou I, Ali C, Maillasson M, Crepaldi T, Comoglio P, Lemarchand E, Agin V, Roussel BD, Vivien D. Two-Chains Tissue Plasminogen Activator Unifies Met and NMDA Receptor Signalling to Control Neuronal Survival. Int J Mol Sci 2021; 22:ijms222413483. [PMID: 34948279 PMCID: PMC8707453 DOI: 10.3390/ijms222413483] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 11/16/2022] Open
Abstract
Tissue-type plasminogen activator (tPA) plays roles in the development and the plasticity of the nervous system. Here, we demonstrate in neurons, that by opposition to the single chain form (sc-tPA), the two-chains form of tPA (tc-tPA) activates the MET receptor, leading to the recruitment of N-Methyl-d-Aspartate receptors (NMDARs) and to the endocytosis and proteasome-dependent degradation of NMDARs containing the GluN2B subunit. Accordingly, tc-tPA down-regulated GluN2B-NMDAR-driven signalling, a process prevented by blockers of HGFR/MET and mimicked by its agonists, leading to a modulation of neuronal death. Thus, our present study unmasks a new mechanism of action of tPA, with its two-chains form mediating a crosstalk between MET and the GluN2B subunit of NMDARs to control neuronal survival.
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Affiliation(s)
- Elodie Hedou
- Normandie University, UNICAEN, INSERM U1237, Etablissement Français du Sang, Physiopathology and Imaging of Neurological Disorders (PhIND), Cyceron, Institut Blood and Brain @ Caen-Normandie (BB@C), 14000 Caen, France; (E.H.); (S.D.); (A.C.); (A.V.); (A.M.T.); (H.T.); (I.B.); (C.A.); (V.A.); (D.V.)
| | - Sara Douceau
- Normandie University, UNICAEN, INSERM U1237, Etablissement Français du Sang, Physiopathology and Imaging of Neurological Disorders (PhIND), Cyceron, Institut Blood and Brain @ Caen-Normandie (BB@C), 14000 Caen, France; (E.H.); (S.D.); (A.C.); (A.V.); (A.M.T.); (H.T.); (I.B.); (C.A.); (V.A.); (D.V.)
| | - Arnaud Chevilley
- Normandie University, UNICAEN, INSERM U1237, Etablissement Français du Sang, Physiopathology and Imaging of Neurological Disorders (PhIND), Cyceron, Institut Blood and Brain @ Caen-Normandie (BB@C), 14000 Caen, France; (E.H.); (S.D.); (A.C.); (A.V.); (A.M.T.); (H.T.); (I.B.); (C.A.); (V.A.); (D.V.)
| | - Alexandre Varangot
- Normandie University, UNICAEN, INSERM U1237, Etablissement Français du Sang, Physiopathology and Imaging of Neurological Disorders (PhIND), Cyceron, Institut Blood and Brain @ Caen-Normandie (BB@C), 14000 Caen, France; (E.H.); (S.D.); (A.C.); (A.V.); (A.M.T.); (H.T.); (I.B.); (C.A.); (V.A.); (D.V.)
| | - Audrey M. Thiebaut
- Normandie University, UNICAEN, INSERM U1237, Etablissement Français du Sang, Physiopathology and Imaging of Neurological Disorders (PhIND), Cyceron, Institut Blood and Brain @ Caen-Normandie (BB@C), 14000 Caen, France; (E.H.); (S.D.); (A.C.); (A.V.); (A.M.T.); (H.T.); (I.B.); (C.A.); (V.A.); (D.V.)
| | - Hortense Triniac
- Normandie University, UNICAEN, INSERM U1237, Etablissement Français du Sang, Physiopathology and Imaging of Neurological Disorders (PhIND), Cyceron, Institut Blood and Brain @ Caen-Normandie (BB@C), 14000 Caen, France; (E.H.); (S.D.); (A.C.); (A.V.); (A.M.T.); (H.T.); (I.B.); (C.A.); (V.A.); (D.V.)
| | - Isabelle Bardou
- Normandie University, UNICAEN, INSERM U1237, Etablissement Français du Sang, Physiopathology and Imaging of Neurological Disorders (PhIND), Cyceron, Institut Blood and Brain @ Caen-Normandie (BB@C), 14000 Caen, France; (E.H.); (S.D.); (A.C.); (A.V.); (A.M.T.); (H.T.); (I.B.); (C.A.); (V.A.); (D.V.)
| | - Carine Ali
- Normandie University, UNICAEN, INSERM U1237, Etablissement Français du Sang, Physiopathology and Imaging of Neurological Disorders (PhIND), Cyceron, Institut Blood and Brain @ Caen-Normandie (BB@C), 14000 Caen, France; (E.H.); (S.D.); (A.C.); (A.V.); (A.M.T.); (H.T.); (I.B.); (C.A.); (V.A.); (D.V.)
| | - Mike Maillasson
- University of Nantes, CHU Nantes, Inserm UMR1232, CNRS ERL6001, SFR Santé, FED 4203, Inserm UMS 016, CNRS UMS 3556, CRCINA, Impact Platform, 44200 Nantes, France;
| | - Tiziana Crepaldi
- Candiolo Cancer Institute IRCCS-FPO, Candiolo, 10060 Turin, Italy; (T.C.); (P.C.)
| | - Paolo Comoglio
- Candiolo Cancer Institute IRCCS-FPO, Candiolo, 10060 Turin, Italy; (T.C.); (P.C.)
| | - Eloïse Lemarchand
- Faculty of Biology, Medicine and Health, University of Manchester, Oxford Rd, Manchester M13 9PL, UK;
| | - Véronique Agin
- Normandie University, UNICAEN, INSERM U1237, Etablissement Français du Sang, Physiopathology and Imaging of Neurological Disorders (PhIND), Cyceron, Institut Blood and Brain @ Caen-Normandie (BB@C), 14000 Caen, France; (E.H.); (S.D.); (A.C.); (A.V.); (A.M.T.); (H.T.); (I.B.); (C.A.); (V.A.); (D.V.)
| | - Benoit D. Roussel
- Normandie University, UNICAEN, INSERM U1237, Etablissement Français du Sang, Physiopathology and Imaging of Neurological Disorders (PhIND), Cyceron, Institut Blood and Brain @ Caen-Normandie (BB@C), 14000 Caen, France; (E.H.); (S.D.); (A.C.); (A.V.); (A.M.T.); (H.T.); (I.B.); (C.A.); (V.A.); (D.V.)
- Correspondence: ; Tel.: +33-2-31470166; Fax: +33-2-31470222
| | - Denis Vivien
- Normandie University, UNICAEN, INSERM U1237, Etablissement Français du Sang, Physiopathology and Imaging of Neurological Disorders (PhIND), Cyceron, Institut Blood and Brain @ Caen-Normandie (BB@C), 14000 Caen, France; (E.H.); (S.D.); (A.C.); (A.V.); (A.M.T.); (H.T.); (I.B.); (C.A.); (V.A.); (D.V.)
- Department of Clinical Research, Caen-Normandie University Hospital, CHU, Avenue de la Côte de Nacre, 14000 Caen, France
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Kamitakahara AK, Ali Marandi Ghoddousi R, Lanjewar AL, Magalong VM, Wu HH, Levitt P. MET Receptor Tyrosine Kinase Regulates Lifespan Ultrasonic Vocalization and Vagal Motor Neuron Development. Front Neurosci 2021; 15:768577. [PMID: 34803597 PMCID: PMC8600253 DOI: 10.3389/fnins.2021.768577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 10/14/2021] [Indexed: 11/25/2022] Open
Abstract
The intrinsic muscles of the larynx are innervated by the vagal motor nucleus ambiguus (nAmb), which provides direct motor control over vocal production in humans and rodents. Here, we demonstrate in mice using the Phox2b Cre line, that conditional embryonic deletion of the gene encoding the MET receptor tyrosine kinase (MET) in the developing brainstem (cKO) results in highly penetrant, severe deficits in ultrasonic vocalization in early postnatal life. Major deficits and abnormal vocalization patterns persist into adulthood in more than 70% of mice, with the remaining recovering the ability to vocalize, reflecting heterogeneity in circuit restitution. We show that underlying the functional deficits, conditional deletion of Met results in a loss of approximately one-third of MET+ nAmb motor neurons, which begins as early as embryonic day 14.5. The loss of motor neurons is specific to the nAmb, as other brainstem motor and sensory nuclei are unaffected. In the recurrent laryngeal nerve, through which nAmb motor neurons project to innervate the larynx, there is a one-third loss of axons in cKO mice. Together, the data reveal a novel, heterogenous MET-dependence, for which MET differentially affects survival of a subset of nAmb motor neurons necessary for lifespan ultrasonic vocal capacity.
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Affiliation(s)
- Anna K. Kamitakahara
- Program in Developmental Neuroscience and Neurogenetics, Children’s Hospital Los Angeles, The Saban Research Institute, Los Angeles, CA, United States
- Department of Pediatrics, Keck School of Medicine of University of Southern California, Los Angeles, CA, United States
| | - Ramin Ali Marandi Ghoddousi
- Program in Developmental Neuroscience and Neurogenetics, Children’s Hospital Los Angeles, The Saban Research Institute, Los Angeles, CA, United States
- Department of Pediatrics, Keck School of Medicine of University of Southern California, Los Angeles, CA, United States
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA, United States
| | - Alexandra L. Lanjewar
- Program in Developmental Neuroscience and Neurogenetics, Children’s Hospital Los Angeles, The Saban Research Institute, Los Angeles, CA, United States
- Department of Pediatrics, Keck School of Medicine of University of Southern California, Los Angeles, CA, United States
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA, United States
| | - Valerie M. Magalong
- Program in Developmental Neuroscience and Neurogenetics, Children’s Hospital Los Angeles, The Saban Research Institute, Los Angeles, CA, United States
- Department of Pediatrics, Keck School of Medicine of University of Southern California, Los Angeles, CA, United States
| | - Hsiao-Huei Wu
- Department of Pediatrics, Keck School of Medicine of University of Southern California, Los Angeles, CA, United States
| | - Pat Levitt
- Program in Developmental Neuroscience and Neurogenetics, Children’s Hospital Los Angeles, The Saban Research Institute, Los Angeles, CA, United States
- Department of Pediatrics, Keck School of Medicine of University of Southern California, Los Angeles, CA, United States
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Ma X, Wei J, Cui Y, Xia B, Zhang L, Nehme A, Zuo Y, Ferguson D, Levitt P, Qiu S. Disrupted Timing of MET Signaling Derails the Developmental Maturation of Cortical Circuits and Leads to Altered Behavior in Mice. Cereb Cortex 2021; 32:1769-1786. [PMID: 34470051 PMCID: PMC9016286 DOI: 10.1093/cercor/bhab323] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/11/2021] [Accepted: 08/12/2021] [Indexed: 01/21/2023] Open
Abstract
The molecular regulation of the temporal dynamics of circuit maturation is a key contributor to the emergence of normal structure-function relations. Developmental control of cortical MET receptor tyrosine kinase, expressed early postnatally in subpopulations of excitatory neurons, has a pronounced impact on the timing of glutamatergic synapse maturation and critical period plasticity. Here, we show that using a controllable overexpression (cto-Met) transgenic mouse, extending the duration of MET signaling after endogenous Met is switched off leads to altered molecular constitution of synaptic proteins, persistent activation of small GTPases Cdc42 and Rac1, and sustained inhibitory phosphorylation of cofilin. These molecular changes are accompanied by an increase in the density of immature dendritic spines, impaired cortical circuit maturation of prefrontal cortex layer 5 projection neurons, and altered laminar excitatory connectivity. Two photon in vivo imaging of dendritic spines reveals that cto-Met enhances de novo spine formation while inhibiting spine elimination. Extending MET signaling for two weeks in developing cortical circuits leads to pronounced repetitive activity and impaired social interactions in adult mice. Collectively, our data revealed that temporally controlled MET signaling as a critical mechanism for controlling cortical circuit development and emergence of normal behavior.
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Affiliation(s)
- Xiaokuang Ma
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ 85004, USA
| | - Jing Wei
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ 85004, USA
| | - Yuehua Cui
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ 85004, USA
| | - Baomei Xia
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ 85004, USA
| | - Le Zhang
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ 85004, USA
| | - Antoine Nehme
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ 85004, USA
| | - Yi Zuo
- Department of Molecular, Cellular and Developmental Neurobiology, University of California at Santa Cruz, Santa Cruz, CA 95064, USA
| | - Deveroux Ferguson
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ 85004, USA
| | - Pat Levitt
- Program in Developmental Neuroscience and Developmental Neurogenetics, The Saban Research Institute and Department of Pediatrics, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA 90027, USA
| | - Shenfeng Qiu
- Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ 85004, USA
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8
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Weng J, Chen Z, Li J, He Q, Chen D, Yang L, Su H, Huang J, Yu S, Huang Q, Xu Q, Guo X. Advanced glycation end products induce endothelial hyperpermeability via β-catenin phosphorylation and subsequent up-regulation of ADAM10. J Cell Mol Med 2021; 25:7746-7759. [PMID: 34227224 PMCID: PMC8358892 DOI: 10.1111/jcmm.16659] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 04/22/2021] [Accepted: 04/26/2021] [Indexed: 12/31/2022] Open
Abstract
Endothelial hyperpermeability is the initial event in the development of diabetic microvascular complications, and advanced glycation end products (AGEs) are suggested to cause much of the endothelial hyperpermeability associated with diabetes mellitus, but the molecular mechanism remains to be characterized. β-catenin reportedly plays dual functions in maintaining normal endothelial permeability by serving both as an adhesive component and a signal transduction component. Here, we found that AGEs induced the phosphorylation of β-catenin at residues Y654 and Y142 and the endothelial hyperpermeability was reversed when the two residues were blocked. In mechanism, phosphorylation of Y654 was blocked by Src inactivation, whereas phosphorylation of Y142 was reduced by a focal adhesion kinase inhibitor. β-catenin Y654 phosphorylation induced by AGEs facilitated the dissociation of vascular endothelial (VE)-cadherin/β-catenin and the impairment of adherens junctions (AJs), whereas β-catenin Y142 phosphorylation favoured the dissociation of β-catenin and α-catenin. Further investigation revealed that β-catenin Y142 phosphorylation was required for AGEs-mediated β-catenin nuclear translocation, and this nuclear-located β-catenin subsequently activated the TCF/LEF pathway. This pathway promotes the transcription of the Wnt target, ADAM10 (a disintegrin and metalloprotease 10), which mediates VE-cadherin shedding and leads to further impairment of AJs. In summary, our study showed the role of β-catenin Y654 and Y142 phosphorylation in AGEs-mediated endothelial hyperpermeability through VE-cadherin/β-catenin/α-catenin dissociation and up-regulation of ADAM10, thereby advancing our understanding of the underlying mechanisms of AGEs-induced microvascular hyperpermeability.
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Affiliation(s)
- Jie Weng
- Department of Pulmonary and Critical Care MedicineZhujiang HospitalSouthern Medical UniversityGuangzhouChina
- Department of PathophysiologyGuangdong Provincial Key Laboratory of Shock and MicrocirculationSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhouChina
| | - Zhenfeng Chen
- Department of PathophysiologyGuangdong Provincial Key Laboratory of Shock and MicrocirculationSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhouChina
| | - Jieyu Li
- Department of PathophysiologyGuangdong Provincial Key Laboratory of Shock and MicrocirculationSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhouChina
| | - Qi He
- Department of PathophysiologyGuangdong Provincial Key Laboratory of Shock and MicrocirculationSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhouChina
| | - Deshu Chen
- Department of PathophysiologyGuangdong Provincial Key Laboratory of Shock and MicrocirculationSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhouChina
| | - Lin Yang
- Guangzhou Special Service Sanatorium Center of the Rocket ForceGuangzhouChina
| | - Haiying Su
- Department of PathophysiologyGuangdong Provincial Key Laboratory of Shock and MicrocirculationSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhouChina
| | - Junlin Huang
- Department of PathophysiologyGuangdong Provincial Key Laboratory of Shock and MicrocirculationSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhouChina
| | - Shengxiang Yu
- Department of PathophysiologyGuangdong Provincial Key Laboratory of Shock and MicrocirculationSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhouChina
| | - Qiaobing Huang
- Department of PathophysiologyGuangdong Provincial Key Laboratory of Shock and MicrocirculationSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhouChina
| | - Qiulin Xu
- Department of Emergency and Critical MedicineGuangdong Provincial People’s HospitalGuangdong Academy of Medical ScienceGuangzhouChina
| | - Xiaohua Guo
- Department of PathophysiologyGuangdong Provincial Key Laboratory of Shock and MicrocirculationSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhouChina
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9
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Jeckel P, Kriebel M, Volkmer H. Autism Spectrum Disorder Risk Factor Met Regulates the Organization of Inhibitory Synapses. Front Mol Neurosci 2021; 14:659856. [PMID: 34054427 PMCID: PMC8155383 DOI: 10.3389/fnmol.2021.659856] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 04/09/2021] [Indexed: 12/27/2022] Open
Abstract
A common hypothesis explains autism spectrum disorder (ASD) as a neurodevelopmental disorder linked to excitatory/inhibitory (E/I) imbalance in neuronal network connectivity. Mutation of genes including Met and downstream signaling components, e.g., PTEN, Tsc2 and, Rheb are involved in the control of synapse formation and stabilization and were all considered as risk genes for ASD. While the impact of Met on glutamatergic synapses was widely appreciated, its contribution to the stability of inhibitory, GABAergic synapses is poorly understood. The stabilization of GABAergic synapses depends on clustering of the postsynaptic scaffolding protein gephyrin. Here, we show in vivo and in vitro that Met is necessary and sufficient for the stabilization of GABAergic synapses via induction of gephyrin clustering. Likewise, we provide evidence for Met-dependent gephyrin clustering via activation of mTOR. Our results support the notion that deficient GABAergic signaling represents a pathomechanism for ASD.
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Affiliation(s)
- Pauline Jeckel
- Department of Pharma and Biotech, NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany
| | - Martin Kriebel
- Department of Pharma and Biotech, NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany
| | - Hansjürgen Volkmer
- Department of Pharma and Biotech, NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany
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10
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Kast RJ, Wu HH, Levitt P. Developmental Connectivity and Molecular Phenotypes of Unique Cortical Projection Neurons that Express a Synapse-Associated Receptor Tyrosine Kinase. Cereb Cortex 2020; 29:189-201. [PMID: 29190358 DOI: 10.1093/cercor/bhx318] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 11/01/2017] [Indexed: 12/15/2022] Open
Abstract
The complex circuitry and cell-type diversity of the cerebral cortex are required for its high-level functions. The mechanisms underlying the diversification of cortical neurons during prenatal development have received substantial attention, but understanding of neuronal heterogeneity is more limited during later periods of cortical circuit maturation. To address this knowledge gap, connectivity analysis and molecular phenotyping of cortical neuron subtypes that express the developing synapse-enriched MET receptor tyrosine kinase were performed. Experiments used a MetGFP transgenic mouse line, combined with coexpression analysis of class-specific molecular markers and retrograde connectivity mapping. The results reveal that MET is expressed by a minor subset of subcerebral and a larger number of intratelencephalic projection neurons. Remarkably, MET is excluded from most layer 6 corticothalamic neurons. These findings are particularly relevant for understanding the maturation of discrete cortical circuits, given converging evidence that MET influences dendritic elaboration and glutamatergic synapse maturation. The data suggest that classically defined cortical projection classes can be further subdivided based on molecular characteristics that likely influence synaptic maturation and circuit wiring. Additionally, given that MET is classified as a high confidence autism risk gene, the data suggest that projection neuron subpopulations may be differentially vulnerable to disorder-associated genetic variation.
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Affiliation(s)
- Ryan J Kast
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA, USA.,Department of Pediatrics, The Saban Research Institute, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.,The Institute for the Developing Mind, The Saban Research Institute, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Hsiao-Huei Wu
- Department of Pediatrics, The Saban Research Institute, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.,The Institute for the Developing Mind, The Saban Research Institute, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Pat Levitt
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA, USA.,Department of Pediatrics, The Saban Research Institute, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.,The Institute for the Developing Mind, The Saban Research Institute, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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11
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Kast RJ, Levitt P. Precision in the development of neocortical architecture: From progenitors to cortical networks. Prog Neurobiol 2019; 175:77-95. [PMID: 30677429 PMCID: PMC6402587 DOI: 10.1016/j.pneurobio.2019.01.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 01/02/2019] [Accepted: 01/21/2019] [Indexed: 02/07/2023]
Abstract
Of all brain regions, the 6-layered neocortex has undergone the most dramatic changes in size and complexity during mammalian brain evolution. These changes, occurring in the context of a conserved set of organizational features that emerge through stereotypical developmental processes, are considered responsible for the cognitive capacities and sensory specializations represented within the mammalian clade. The modern experimental era of developmental neurobiology, spanning 6 decades, has deciphered a number of mechanisms responsible for producing the diversity of cortical neuron types, their precise connectivity and the role of gene by environment interactions. Here, experiments providing insight into the development of cortical projection neuron differentiation and connectivity are reviewed. This current perspective integrates discussion of classic studies and new findings, based on recent technical advances, to highlight an improved understanding of the neuronal complexity and precise connectivity of cortical circuitry. These descriptive advances bring new opportunities for studies related to the developmental origins of cortical circuits that will, in turn, improve the prospects of identifying pathogenic targets of neurodevelopmental disorders.
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Affiliation(s)
- Ryan J Kast
- Department of Pediatrics and Program in Developmental Neuroscience and Developmental Neurogenetics, The Saban Research Institute, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90027, USA
| | - Pat Levitt
- Department of Pediatrics and Program in Developmental Neuroscience and Developmental Neurogenetics, The Saban Research Institute, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90027, USA.
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12
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Semaphorin4D Induces Inhibitory Synapse Formation by Rapid Stabilization of Presynaptic Boutons via MET Coactivation. J Neurosci 2019; 39:4221-4237. [PMID: 30914448 DOI: 10.1523/jneurosci.0215-19.2019] [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: 01/23/2019] [Revised: 03/13/2019] [Accepted: 03/17/2019] [Indexed: 11/21/2022] Open
Abstract
Changes in inhibitory connections are essential for experience-dependent circuit adaptations. Defects in inhibitory synapses are linked to neurodevelopmental disorders, but the molecular processes underlying inhibitory synapse formation are not well understood. Here we use high-resolution two-photon microscopy in organotypic hippocampal slices from GAD65-GFP mice of both sexes to examine the signaling pathways induced by the postsynaptic signaling molecule Semaphorin4D (Sema4D) during inhibitory synapse formation. By monitoring changes in individual GFP-labeled presynaptic boutons, we found that the primary action of Sema4D is to induce stabilization of presynaptic boutons within tens of minutes. Stabilized boutons rapidly recruited synaptic vesicles, followed by accumulation of postsynaptic gephyrin and were functional after 24 h, as determined by electrophysiology and immunohistochemistry. Inhibitory boutons are only sensitive to Sema4D at a specific stage during synapse formation and sensitivity to Sema4D is regulated by network activity. We further examined the intracellular signaling cascade triggered by Sema4D and found that bouton stabilization occurs through rapid remodeling of the actin cytoskeleton. This could be mimicked by the actin-depolymerizing drug latrunculin B or by reducing ROCK activity. We discovered that the intracellular signaling cascade requires activation of the receptor tyrosine kinase MET, which is a well known autism risk factor. By using a viral approach to reduce MET levels specifically in inhibitory neurons, we found that their axons are no longer sensitive to Sema4D signaling. Together, our data yield important insights into the molecular pathway underlying activity-dependent Sema4D-induced synapse formation and reveal a novel role for presynaptic MET at inhibitory synapses.SIGNIFICANCE STATEMENT GABAergic synapses provide the main inhibitory control of neuronal activity in the brain. We wanted to unravel the sequence of molecular events that take place when formation of inhibitory synapses is triggered by a specific signaling molecule, Sema4D. We find that this signaling pathway depends on network activity and involves specific remodeling of the intracellular actin cytoskeleton. We also reveal a previously unknown role for MET at inhibitory synapses. Our study provides novel insights into the dynamic process of inhibitory synapse formation. As defects in GABAergic synapses have been implied in many brain disorders, and mutations in MET are strong risk factors for autism, our findings urge for a further investigation of the role of MET at inhibitory synapses.
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13
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Han KA, Um JW, Ko J. Intracellular protein complexes involved in synapse assembly in presynaptic neurons. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2018; 116:347-373. [PMID: 31036296 DOI: 10.1016/bs.apcsb.2018.11.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The presynaptic active zone, composed of evolutionarily conserved protein complexes, is a specialized area that serves to orchestrate precise and efficient neurotransmitter release by organizing various presynaptic proteins involved in mediating docking and priming of synaptic vesicles, recruiting voltage-gated calcium channels, and modulating presynaptic nerve terminals with aligned postsynaptic structures. Among membrane proteins localized to active zone, presynaptic neurexins and LAR-RPTPs (leukocyte common antigen-related receptor tyrosine phosphatase) have emerged as hubs that orchestrate both shared and distinct extracellular synaptic adhesion pathways. In this chapter, we discuss intracellular signaling cascades involved in recruiting various intracellular proteins at both excitatory and inhibitory synaptic sites. In particular, we highlight recent studies on key active zone proteins that physically and functionally link these cascades with neurexins and LAR-RPTPs in both vertebrate and invertebrate model systems. These studies allow us to build a general, universal view of how presynaptic active zones operate together with postsynaptic structures in neural circuits.
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Affiliation(s)
- Kyung Ah Han
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Korea
| | - Ji Won Um
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Korea
| | - Jaewon Ko
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Korea.
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Gomez-Fernandez A, de la Torre-Aguilar MJ, Gil-Campos M, Flores-Rojas K, Cruz-Rico MD, Martin-Borreguero P, Perez-Navero JL. Children With Autism Spectrum Disorder With Regression Exhibit a Different Profile in Plasma Cytokines and Adhesion Molecules Compared to Children Without Such Regression. Front Pediatr 2018; 6:264. [PMID: 30320048 PMCID: PMC6169449 DOI: 10.3389/fped.2018.00264] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 09/05/2018] [Indexed: 12/27/2022] Open
Abstract
Background: In the etiopathogenesis of autism spectrum disorder (ASD), it has been suggested that a proinflammatory condition, as well as an alteration in adhesion molecules in the early stages of neurodevelopment, may play a role in the pathophysiology of the disorder. This study set out to evaluate the plasma levels of certain inflammatory cytokines, adhesion molecules, and growth factors in a sample of pediatric patients with ASD and compare them to the levels in a control group of healthy children. Methods: Fifty-four children (45 males and nine females) aged 2-6, who were diagnosed with ASD, and a control group of 54 typically-developing children of similar ages were selected. The diagnosis of ASD was carried out in accordance with the DSM-5 criteria and the data obtained from a developmental semi-structured clinical interview and the ADOS evaluation test. Additional testing was carried out to identify the children's developmental level and severity of ASD symptomatology. Patients with ASD were further divided into two subgroups based on developmental parameters: ASD children with neurodevelopmental regression (AMR) and ASD children without neurodevelopmental regression (ANMR). Analyses of plasma molecules, such as cathepsin, IL1β, IL6, IL8, MPO, RANTES, MCP, BDNF, PAI NCAM, sICAM, sVCAM and NGF, were performed. Results: Higher levels of NGF were observed in the ASD group compared with the levels in the control group (p < 0.05). However, in the analysis of the ASD subgroups, lower plasma levels of NCAM and higher levels of NGF were found in the group of ASD children without developmental regression compared to the levels in the group of typically-developing children. Conclusions: These results suggest differences that could be related to different pathophysiological mechanisms in ASD. There is not a specific profile for the expression of relevant plasma cytokines, adhesion molecules or growth factors in children with ASD compared with that in typically-developing children. However, in the ANMR and AMR subgroups, some of the adhesion molecules and neuronal growth factors show differences that may be related to synaptogenesis.
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Affiliation(s)
- Antonio Gomez-Fernandez
- Department of Pediatrics, Reina Sofia University Hospital, University of Córdoba, Maimónides Institute for Biomedical Research of Córdoba (IMIBIC), Cordoba, Spain
| | - Maria J de la Torre-Aguilar
- Department of Pediatrics, Reina Sofia University Hospital, University of Córdoba, Maimónides Institute for Biomedical Research of Córdoba (IMIBIC), Cordoba, Spain
| | - Mercedes Gil-Campos
- Pediatric Metabolism Unit, Reina Sofia University Hospital, Maimónides Institute for Biomedical Research of Córdoba (IMIBIC), University of Córdoba, Centro de Investigación Biomédica en Red-Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Cordoba, Spain
| | - Katherine Flores-Rojas
- Pediatric Metabolism Unit, Reina Sofia University Hospital, Maimónides Institute for Biomedical Research of Córdoba (IMIBIC), University of Córdoba, Centro de Investigación Biomédica en Red-Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Cordoba, Spain
| | - Maria D Cruz-Rico
- Department of Biochemistry and Molecular Biology II, Institute of Nutrition and Food Technology, Center of Biomedical Research, University of Granada, Granada, Spain
| | - Pilar Martin-Borreguero
- Department of Child and Adolescent Clinical Psychiatry and Psychology, Reina Sofia University Hospital, Maimónides Institute for Biomedical Research of Córdoba (IMIBIC), Cordoba, Spain
| | - Juan Luis Perez-Navero
- Department of Pediatrics, Reina Sofia University Hospital, University of Córdoba, Maimónides Institute for Biomedical Research of Córdoba (IMIBIC), Cordoba, Spain
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15
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Kamitakahara A, Wu HH, Levitt P. Distinct projection targets define subpopulations of mouse brainstem vagal neurons that express the autism-associated MET receptor tyrosine kinase. J Comp Neurol 2017; 525:3787-3808. [PMID: 28758209 DOI: 10.1002/cne.24294] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 07/14/2017] [Accepted: 07/17/2017] [Indexed: 12/11/2022]
Abstract
Detailed anatomical tracing and mapping of the viscerotopic organization of the vagal motor nuclei has provided insight into autonomic function in health and disease. To further define specific cellular identities, we paired information based on visceral connectivity with a cell-type specific marker of a subpopulation of neurons in the dorsal motor nucleus of the vagus (DMV) and nucleus ambiguus (nAmb) that express the autism-associated MET receptor tyrosine kinase. As gastrointestinal disturbances are common in children with autism spectrum disorder (ASD), we sought to define the relationship between MET-expressing (MET+) neurons in the DMV and nAmb, and the gastrointestinal tract. Using wholemount tissue staining and clearing, or retrograde tracing in a METEGFP transgenic mouse, we identify three novel subpopulations of EGFP+ vagal brainstem neurons: (a) EGFP+ neurons in the nAmb projecting to the esophagus or laryngeal muscles, (b) EGFP+ neurons in the medial DMV projecting to the stomach, and (b) EGFP+ neurons in the lateral DMV projecting to the cecum and/or proximal colon. Expression of the MET ligand, hepatocyte growth factor (HGF), by tissues innervated by vagal motor neurons during fetal development reveal potential sites of HGF-MET interaction. Furthermore, similar cellular expression patterns of MET in the brainstem of both the mouse and nonhuman primate suggests that MET expression at these sites is evolutionarily conserved. Together, the data suggest that MET+ neurons in the brainstem vagal motor nuclei are anatomically positioned to regulate distinct portions of the gastrointestinal tract, with implications for the pathophysiology of gastrointestinal comorbidities of ASD.
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Affiliation(s)
- Anna Kamitakahara
- Program in Developmental Neurogenetics, Institute for the Developing Mind, The Saban Resarch Institute, Children's Hospital Los Angeles, Los Angeles, California
| | - Hsiao-Huei Wu
- Keck School of Medicine of University of Southern California, Los Angeles, California
| | - Pat Levitt
- Program in Developmental Neurogenetics, Institute for the Developing Mind, The Saban Resarch Institute, Children's Hospital Los Angeles, Los Angeles, California.,Department of Pediatrics, Keck School of Medicine of University of Southern California, Los Angeles, California.,University of Southern California Program in Neuroscience, Los Angeles, California
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16
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Kast RJ, Wu HH, Williams P, Gaspar P, Levitt P. Specific Connectivity and Unique Molecular Identity of MET Receptor Tyrosine Kinase Expressing Serotonergic Neurons in the Caudal Dorsal Raphe Nuclei. ACS Chem Neurosci 2017; 8:1053-1064. [PMID: 28375615 DOI: 10.1021/acschemneuro.7b00020] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Molecular characterization of neurons across brain regions has revealed new taxonomies for understanding functional diversity even among classically defined neuronal populations. Neuronal diversity has become evident within the brain serotonin (5-HT) system, which is far more complex than previously appreciated. However, until now it has been difficult to define subpopulations of 5-HT neurons based on molecular phenotypes. We demonstrate that the MET receptor tyrosine kinase (MET) is specifically expressed in a subset of 5-HT neurons within the caudal part of the dorsal raphe nuclei (DRC) that is encompassed by the classic B6 serotonin cell group. Mapping from embryonic day 16 through adulthood reveals that MET is expressed almost exclusively in the DRC as a condensed, paired nucleus, with an additional sparse set of MET+ neurons scattered within the median raphe. Retrograde tracing experiments reveal that MET-expressing 5-HT neurons provide substantial serotonergic input to the ventricular/subventricular region that contains forebrain stem cells, but do not innervate the dorsal hippocampus or entorhinal cortex. Conditional anterograde tracing experiments show that 5-HT neurons in the DRC/B6 target additional forebrain structures such as the medial and lateral septum and the ventral hippocampus. Molecular neuroanatomical analysis identifies 14 genes that are enriched in DRC neurons, including 4 neurotransmitter/neuropeptide receptors and 2 potassium channels. These analyses will lead to future studies determining the specific roles that 5-HTMET+ neurons contribute to the broader set of functions regulated by the serotonergic system.
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Affiliation(s)
| | | | | | - Patricia Gaspar
- Inserm, UMRS-839, Université
Pierre et Marie Curie, and Institut du Fer à Moulin, 75005, Paris, France
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