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Surbhi, Wittmann G, Low MJ, Lechan RM. Adult-born proopiomelanocortin neurons derived from Rax-expressing precursors mitigate the metabolic effects of congenital hypothalamic proopiomelanocortin deficiency. Mol Metab 2021; 53:101312. [PMID: 34329773 PMCID: PMC8383116 DOI: 10.1016/j.molmet.2021.101312] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 07/12/2021] [Accepted: 07/25/2021] [Indexed: 12/19/2022] Open
Abstract
OBJECTIVE Proopiomelanocortin (POMC) neurons of the hypothalamic arcuate nucleus are essential regulators of energy balance. Selective loss of POMC production in these cells results in extreme obesity and metabolic comorbidities. Neurogenesis occurs in the adult hypothalamus, but it remains uncertain whether functional POMC neurons emerge in physiologically significant numbers during adulthood. Here, we tested whether Rax-expressing precursors generate POMC neurons in adult mice and rescue the metabolic phenotype caused by congenital hypothalamic POMC deficiency. METHODS Initially, we identified hypothalamic Rax-expressing cell types using wild-type and Rax-CreERT2:Ai34D mice. Then we generated compound Rax-CreERT2:ArcPomcloxTB/loxTB mice in which endogenous hypothalamic Pomc expression is silenced, but can be restored by tamoxifen administration selectively in neurons derived from Rax+ progenitors. The number of POMC neurons generated by Rax+ progenitors in adult mice and their axonal projections was determined. The metabolic effects of these neurons were assessed by measuring food intake, bodyweight, and body composition, along with glucose and insulin levels. RESULTS We found that Rax is expressed by tanycytes and a previously unrecognized cell type in the hypothalamic parenchyma of adult mice. Rax+ progenitors generated ~10% of the normal adult hypothalamic POMC neuron population within two weeks of tamoxifen treatment. The same rate and steady state of POMC neurogenesis persisted from young adult to aged mice. These new POMC neurons established terminal projections to brain regions that were involved in energy homeostasis. Mice with Rax+ progenitor-derived POMC neurons had reduced body fat mass, improved glucose tolerance, increased insulin sensitivity, and decreased bodyweight in proportion to the number of new POMC neurons. CONCLUSIONS These data demonstrate that Rax+ progenitors generate POMC neurons in sufficient numbers during adulthood to mitigate the metabolic abnormalities of hypothalamic POMC-deficient mice. The findings suggest that adult hypothalamic neurogenesis is a robust phenomenon in mice that can significantly impact energy homeostasis.
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Affiliation(s)
- Surbhi
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, 2800 Plymouth Rd, Ann Arbor, MI, 48109, USA.
| | - Gábor Wittmann
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, Tufts Medical Center, 800 Washington St, Boston, MA, 02111, USA.
| | - Malcolm J Low
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, 2800 Plymouth Rd, Ann Arbor, MI, 48109, USA.
| | - Ronald M Lechan
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, Tufts Medical Center, 800 Washington St, Boston, MA, 02111, USA.
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Davis ES, Voss G, Miesfeld JB, Zarate-Sanchez J, Voss SR, Glaser T. The rax homeobox gene is mutated in the eyeless axolotl, Ambystoma mexicanum. Dev Dyn 2021; 250:807-821. [PMID: 32864847 PMCID: PMC8907009 DOI: 10.1002/dvdy.246] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Accepted: 08/11/2020] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Vertebrate eye formation requires coordinated inductive interactions between different embryonic tissue layers, first described in amphibians. A network of transcription factors and signaling molecules controls these steps, with mutations causing severe ocular, neuronal, and craniofacial defects. In eyeless mutant axolotls, eye morphogenesis arrests at the optic vesicle stage, before lens induction, and development of ventral forebrain structures is disrupted. RESULTS We identified a 5-bp deletion in the rax (retina and anterior neural fold homeobox) gene, which was tightly linked to the recessive eyeless (e) axolotl locus in an F2 cross. This frameshift mutation, in exon 2, truncates RAX protein within the homeodomain (P154fs35X). Quantitative RNA analysis shows that mutant and wild-type rax transcripts are equally abundant in E/e embryos. Translation appears to initiate from dual start codons, via leaky ribosome scanning, a conserved feature among gnathostome RAX proteins. Previous data show rax is expressed in the optic vesicle and diencephalon, deeply conserved among metazoans, and required for eye formation in other species. CONCLUSION The eyeless axolotl mutation is a null allele in the rax homeobox gene, with primary defects in neural ectoderm, including the retinal and hypothalamic primordia.
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Affiliation(s)
- Erik S. Davis
- Department of Cell Biology and Human Anatomy, University of California Davis School of Medicine, Davis, California
| | - Gareth Voss
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, and Ambystoma Genetic Stock Center, University of Kentucky, Lexington, Kentucky
| | - Joel B. Miesfeld
- Department of Cell Biology and Human Anatomy, University of California Davis School of Medicine, Davis, California
| | - Juan Zarate-Sanchez
- Department of Cell Biology and Human Anatomy, University of California Davis School of Medicine, Davis, California
- Davis Senior High School, Davis, California
| | - S. Randal Voss
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, and Ambystoma Genetic Stock Center, University of Kentucky, Lexington, Kentucky
| | - Tom Glaser
- Department of Cell Biology and Human Anatomy, University of California Davis School of Medicine, Davis, California
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Kon T, Furukawa T. Origin and evolution of the Rax homeobox gene by comprehensive evolutionary analysis. FEBS Open Bio 2020; 10:657-673. [PMID: 32144893 PMCID: PMC7137802 DOI: 10.1002/2211-5463.12832] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 02/26/2020] [Accepted: 03/04/2020] [Indexed: 12/20/2022] Open
Abstract
Rax is one of the key transcription factors crucial for vertebrate eye development. In this study, we conducted comprehensive evolutionary analysis of Rax. We found that Bilateria and Cnidaria possess Rax, but Placozoa, Porifera, and Ctenophora do not, implying that the origin of the Rax gene dates back to the common ancestor of Cnidaria and Bilateria. The results of molecular phylogenetic and synteny analyses on Rax loci between jawed and jawless vertebrates indicate that segmental duplication of the Rax locus occurred in an early common ancestor of jawed vertebrates, resulting in two Rax paralogs in jawed vertebrates, Rax and Rax2. By analyzing 86 mammalian genomes from all four major groups of mammals, we found that at least five independent Rax2 gene loss events occurred in mammals. This study may provide novel insights into the evolution of the eye.
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Affiliation(s)
- Tetsuo Kon
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Suita, Japan
| | - Takahisa Furukawa
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Suita, Japan
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Takata N, Eiraku M, Sakakura E. Data describing Rax positive optic-vesicle generation from mouse embryonic stem cells in vitro. Data Brief 2016; 8:465-9. [PMID: 27358906 PMCID: PMC4915947 DOI: 10.1016/j.dib.2016.05.070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 05/18/2016] [Accepted: 05/27/2016] [Indexed: 11/28/2022] Open
Abstract
This article contains data related to the research article entitled “Specification of embryonic stem cell-derived tissues into eye fields by Wnt signaling using rostral diencephalic tissue-inducing culture” Sakakura (2016) [1]. Mouse embryonic stem cells (ESC) were used for the generation of optic vesicle-like tissues in vitro. In this article we described data in which a Rax::GFP knock-in ESC line was used to monitor the formation of optic tissues. In addition, we also described the data of regional marker expression of Rax, Sox2 and Pax6 in vivo around the forebrain and the eye tissues for comparative purposes. These data can be valuable to researchers interested in investigating forebrain and eye tissue development.
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Affiliation(s)
- Nozomu Takata
- Laboratory for in vitro Histogenesis, RIKEN Center for Developmental Biology, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan; Center for Vascular and Developmental Biology, Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, 303 East Superior Street, Chicago 60611, IL, USA
| | - Mototsugu Eiraku
- Laboratory for in vitro Histogenesis, RIKEN Center for Developmental Biology, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Eriko Sakakura
- Laboratory for in vitro Histogenesis, RIKEN Center for Developmental Biology, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
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Sakakura E, Eiraku M, Takata N. Specification of embryonic stem cell-derived tissues into eye fields by Wnt signaling using rostral diencephalic tissue-inducing culture. Mech Dev 2016; 141:90-9. [PMID: 27151576 DOI: 10.1016/j.mod.2016.05.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 04/26/2016] [Accepted: 05/01/2016] [Indexed: 01/13/2023]
Abstract
The eyes are subdivided from the rostral diencephalon in early development. How the neuroectoderm regulates this subdivision, however, is largely unknown. Taking advantage of embryonic stem cell (ESC) culture using a Rax reporter line to monitor rostral diencephalon formation, we found that ESC-derived tissues at day 7 grown in Glasgow Minimum Expression Media (GMEM) containing knockout serum replacement (KSR) exhibited higher levels of expression of axin2, a Wnt target gene, than those grown in chemically defined medium (CDM). Surprisingly, Wnt agonist facilitated eye field-like tissue specification in CDM. In contrast, the addition of Wnt antagonist diminished eye field tissue formation in GMEM+KSR. Furthermore, the morphological formation of the eye tissue anlage, including the optic vesicle, was accompanied by Wnt signaling activation. Additionally, using CDM culture, we developed an efficient method for generating Rax+/Chx10+ retinal progenitors, which could become fully stratified retina. Here we provide a new avenue for exploring the mechanisms of eye field specification in vitro.
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Takata N, Sakakura E, Sasai Y. Activation of Wnt/ß-catenin signaling in ESC promotes rostral forebrain differentiation in vitro. In Vitro Cell Dev Biol Anim 2016; 52:374-82. [PMID: 26563247 DOI: 10.1007/s11626-015-9975-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 10/27/2015] [Indexed: 01/10/2023]
Abstract
Wnt/ß-catenin signaling is crucial for maintenance of pluripotent state of embryonic stem cell (ESC). However, it is unclear how Wnt/ß-catenin signaling affects the differentiation ability of ESC, especially with regard to rostral forebrain cells. Here, using Rax, rostral forebrain marker, and Wnt/ß-catenin reporter lines, we report ratio of Rax+ and Wnt responding tissue (Wnt+) patterns, which were affected by seeding number of ESC in three-dimensional culture system. Surprisingly, we found ß-catenin level and localization are heterogeneous in ESC colony by immunostaining and time-laps imaging of ß-catenin-mEGFP signals. Moreover, activation of Wnt signaling in ESC promoted expression level and nuclear localization of ß-catenin, and mRNA levels of Wnt antagonists, axin2 and dkk1, leading to upregulating Wnt/ß-catenin reporter in ESC state and Rax expression at differentiation culture day 7. Together, our results suggest that activation of Wnt signaling in ESC promotes the differentiation efficacy of rostral forebrain cells. Wnt-priming culture method may provide a useful tool for applications in the areas of basic science and molecular therapeutics for regenerative medicine.
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Giudetti G, Giannaccini M, Biasci D, Mariotti S, Degl'innocenti A, Perrotta M, Barsacchi G, Andreazzoli M. Characterization of the Rx1-dependent transcriptome during early retinal development. Dev Dyn 2014; 243:1352-61. [PMID: 24801179 DOI: 10.1002/dvdy.24145] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 04/29/2014] [Accepted: 05/04/2014] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND The transcription factor Rx1, also known as Rax, controls key properties of retinal precursors including migration behavior, proliferation, and maintenance of multipotency. However, Rx1 effector genes are largely unknown. RESULTS To identify genes controlled by Rx1 in early retinal precursors, we compared the transcriptome of Xenopus embryos overexpressing Rx1 to that of embryos in which Rx1 was knocked-down. In particular, we selected 52 genes coherently regulated, i.e., actived in Rx1 gain of function and repressed in Rx1 loss of function experiments, or vice versa. RT-qPCR and in situ hybridization confirmed the trend of regulation predicted by microarray data for the selected genes. Most of the genes upregulated by Rx1 are coexpressed with this transcription factor, while downregulated genes are either not expressed or expressed at very low levels in the early developing retina. Putative direct Rx1 target genes, activated by GR-Rx1 in the absence of protein synthesis, include Ephrin B1 and Sh2d3c, an interactor of ephrinB1 receptor, which represent candidate novel effectors for the migration promoting activity of Rx1. CONCLUSIONS This study identifies previously undescribed Rx1 regulated genes mainly involved in transcription regulation, cell migration/adhesion, and cell proliferation that contribute to delineate the molecular mechanisms underlying Rx1 activities.
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Affiliation(s)
- Guido Giudetti
- Unità di Biologia Cellulare e dello Sviluppo, Dipartimento di Biologia, Università di Pisa, Pisa, Italy
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