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Hirayama M, Mure LS, Le HD, Panda S. Neuronal reprogramming of mouse and human fibroblasts using transcription factors involved in suprachiasmatic nucleus development. iScience 2024; 27:109051. [PMID: 38384840 PMCID: PMC10879699 DOI: 10.1016/j.isci.2024.109051] [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: 08/29/2023] [Revised: 10/18/2023] [Accepted: 01/23/2024] [Indexed: 02/23/2024] Open
Abstract
The hypothalamic suprachiasmatic nucleus (SCN) is composed of heterogenous populations of neurons that express signaling peptides such as vasoactive intestinal polypeptide (VIP) and arginine vasopressin (AVP) and regulate circadian rhythms in behavior and physiology. SCN neurons acquire functional and morphological specializations from waves of transcription factors (TFs) that are expressed during neurogenesis. However, the in vitro generation of SCN neurons has never been achieved. Here we supplemented a highly efficient neuronal conversion protocol with TFs that are expressed during SCN neurogenesis, namely Six3, Six6, Dlx2, and Lhx1. Neurons induced from mouse and human fibroblasts predominantly exhibited neuronal properties such as bipolar or multipolar morphologies, GABAergic neurons with expression of VIP. Our study reveals a critical contribution of these TFs to the development of vasoactive intestinal peptide (Vip) expressing neurons in the SCN, suggesting the regenerative potential of neuronal subtypes contained in the SCN for future SCN regeneration and in vitro disease remodeling.
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Affiliation(s)
- Masatoshi Hirayama
- Regulatory Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
- Department of Ophthalmology, School of Medicine, Keio University, Tokyo, Japan
| | - Ludovic S. Mure
- Regulatory Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
- Department of Ophthalmology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Department of BioMedical Research, University of Bern, Bern, Switzerland
| | - Hiep D. Le
- Regulatory Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Satchidananda Panda
- Regulatory Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
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2
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Moccia A, Martin DM. Nervous system development and disease: A focus on trithorax related proteins and chromatin remodelers. Mol Cell Neurosci 2018; 87:46-54. [PMID: 29196188 PMCID: PMC5828982 DOI: 10.1016/j.mcn.2017.11.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 11/08/2017] [Accepted: 11/27/2017] [Indexed: 01/12/2023] Open
Abstract
The nervous system comprises many different cell types including neurons, glia, macrophages, and immune cells, each of which is defined by specific patterns of gene expression, morphology, function, and anatomical location. Establishment of these complex and highly regulated cell fates requires spatial and temporal coordination of gene transcription. Open chromatin (euchromatin) allows transcription factors to interact with gene promoters and activate lineage specific genes, whereas closed chromatin (heterochromatin) remains inaccessible to transcriptional activation. Changes in the genome-wide distribution of euchromatin accompany transcriptional plasticity that allows the diversity of mature cell fates to be generated during development. In the past 20years, many new genes and gene families have been identified to participate in regulation of chromatin accessibility. These genes include chromatin remodelers that interact with Trithorax group (TrxG) and Polycomb group (PcG) proteins to activate or repress transcription, respectively. Here we review the role of TrxG proteins in neurodevelopment and disease.
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Affiliation(s)
- Amanda Moccia
- Department of Human Genetics, The University of Michigan Medical School, Ann Arbor, MI 48109, United States
| | - Donna M Martin
- Department of Human Genetics, The University of Michigan Medical School, Ann Arbor, MI 48109, United States; Department of Pediatrics and Communicable Diseases, The University of Michigan Medical School, Ann Arbor, MI 48109, United States.
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3
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van Ravenswaaij-Arts C, Martin DM. New insights and advances in CHARGE syndrome: Diagnosis, etiologies, treatments, and research discoveries. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2017; 175:397-406. [PMID: 29171162 DOI: 10.1002/ajmg.c.31592] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 10/02/2017] [Accepted: 10/04/2017] [Indexed: 01/17/2023]
Abstract
CHARGE syndrome is a multiple congenital anomaly condition caused, in a majority of individuals, by loss of function pathogenic variants in the gene CHD7. In this special issue of the American Journal of Medical Genetics part C, authors of eleven manuscripts describe specific organ system features of CHARGE syndrome, with a focus on recent developments in diagnosis, etiologies, and treatments. Since 2004, when CHD7 was identified as the major causative gene in CHARGE, several animal models (mice, zebrafish, flies, and frog) and cell-based systems have been developed to explore the underlying pathophysiology of this condition. In this article, we summarize those advances, highlight opportunities for new discoveries, and encourage readers to explore specific organ systems in more detail in each individual article. We hope the excitement around innovative research and development in CHARGE syndrome will encourage others to join this effort, and will stimulate other investigators and professionals to engage with individuals diagnosed as having CHARGE syndrome, their families, and their care providers.
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Affiliation(s)
- Conny van Ravenswaaij-Arts
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Donna M Martin
- Departments of Human Genetics, The University of Michigan Medical School, Ann Arbor, Michigan.,Departments of Pediatrics, The University of Michigan Medical School, Ann Arbor, Michigan
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4
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Choo DI, Tawfik KO, Martin DM, Raphael Y. Inner ear manifestations in CHARGE: Abnormalities, treatments, animal models, and progress toward treatments in auditory and vestibular structures. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2017; 175:439-449. [PMID: 29082607 DOI: 10.1002/ajmg.c.31587] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 09/18/2017] [Accepted: 09/22/2017] [Indexed: 12/25/2022]
Abstract
The inner ear contains the sensory organs for hearing and balance. Both hearing and balance are commonly affected in individuals with CHARGE syndrome (CS), an autosomal dominant condition caused by heterozygous pathogenic variants in the CHD7 gene. Semicircular canal dysplasia or aplasia is the single most prevalent feature in individuals with CHARGE leading to deficient gross motor skills and ambulation. Identification of CHD7 as the major gene affected in CHARGE has enabled acceleration of research in this field. Great progress has been made in understanding the role of CHD7 in the development and function of the inner ear, as well as in related organs such as the middle ear and auditory and vestibular neural pathways. The goals of current research on CHD7 and CS are to (a) improve our understanding of the pathology caused by CHD7 pathogenic variants and (b) to provide better tools for prognosis and treatment. Current studies utilize cells and whole animals, from flies to mammals. The mouse is an excellent model for exploring mechanisms of Chd7 function in the ear, given the evolutionary conservation of ear structure, function, Chd7 expression, and similarity of mutant phenotypes between mice and humans. Newly recognized developmental functions for mouse Chd7 are shedding light on how abnormalities in CHD7 might lead to CS symptoms in humans. Here we review known human inner ear phenotypes associated with CHD7 pathogenic variants and CS, summarize progress toward diagnosis and treatment of inner ear-related pathologies, and explore new avenues for treatment based on basic science discoveries.
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Affiliation(s)
- Daniel I Choo
- Department of Otolaryngology-Head and Neck Surgery, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Kareem O Tawfik
- Department of Otolaryngology-Head and Neck Surgery, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Donna M Martin
- Departments of Pediatrics, The University of Michigan Medical School, Ann Arbor, Michigan.,Department of Human Genetics, The University of Michigan Medical School, Ann Arbor, Michigan
| | - Yehoash Raphael
- Department of Otolaryngology-Head and Neck Surgery, The University of Michigan Medical School, Ann Arbor, Michigan
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5
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Sharma S, Thakurdas P, Sinam B, Joshi D. Paradoxical masking effects of bright photophase and high temperature in Drosophila malerkotliana. Chronobiol Int 2012; 29:157-65. [PMID: 22324554 DOI: 10.3109/07420528.2011.644875] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Synergic contribution of light and temperature is known to cause a paradoxical masking effect (inhibition of activity by bright light and high temperature) on various rhythms of animals. The present study reports the paradoxical masking effects of 1000-lux photophase at 25°C on the locomotor activity rhythm of Drosophila malerkotliana. Flies were subjected to light (L)-dark (D) 12:12 cycles wherein the photophase was varied from 10 to 1000 lux, whereas the scotophase was set to 0 lux in these and subsequent LD cycles. At 10, 100, and 500 lux, the flies were diurnal; however, at 1000 lux they were nocturnal. Transfer from LD 12:12 cycles to continuous darkness (DD) initiated free-running rhythmicity in all flies. Free-running rhythms of the flies switched from the 10-lux to the 500-lux groups started from the last activity-onset phase of the rhythm following 3-5 transient cycles, suggesting involvement of the circadian pacemaker. In contrast, the free-running rhythm of the flies of the 1000-lux group began abruptly from the last lights-on phase of the LD cycle, indicating noninvolvement of the pacemaker. Furthermore, all flies showed nocturnal activity in the two types of LD 12:12 cycles when the photophase was 1000 lux. The first type of LD cycles had three succeeding photophases of 100, 1000, and again 100 lux, whereas the second type of LD cycles had only one photophase of 1000 lux, but the LD 12:12 cycles were reversed to DL 12:12 cycles. Apparently, the combined effects of light and temperature caused such paradoxical masking effects. This hypothesis was tested by repeating the above experiments at 20°C. Flies in all experiments exhibited a diurnal activity pattern, even when the photophase was 1000 lux. Thus, the present study demonstrates that the paradoxical masking effect in D. malerkotliana was caused by the additive influence of light intensity and temperature. This strategy appears to have physiological significance, i.e., to shun and thus protect against the bright photophase at high temperature in the field.
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Affiliation(s)
- Shweta Sharma
- Centre for Biological Rhythm Research, Ahmednagar College, Ahmednagar, Maharashtra State, India
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Hurd EA, Capers PL, Blauwkamp MN, Adams ME, Raphael Y, Poucher HK, Martin DM. Loss of Chd7 function in gene-trapped reporter mice is embryonic lethal and associated with severe defects in multiple developing tissues. Mamm Genome 2007; 18:94-104. [PMID: 17334657 DOI: 10.1007/s00335-006-0107-6] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2006] [Accepted: 11/16/2006] [Indexed: 12/23/2022]
Abstract
CHD7 is a novel chromodomain gene mutated in 60%-80% of humans with CHARGE syndrome, a multiple congenital anomaly condition characterized by ocular coloboma, heart defects, atresia of the choanae, retarded growth and development, genital hypoplasia, and characteristic ear abnormalities including deafness. Phenotypic features of CHARGE are highly variable and incompletely penetrant. To explore developmental roles of CHD7, we generated mice carrying the Chd7(Gt) allele from a Chd7-deficient, gene-trapped lacZ reporter ES cell line. RT-PCR of embryo RNA demonstrated significantly reduced levels of wild-type transcript in Chd7(Gt/Gt) embryos. Chd7(Gt/Gt) embryos survive only up to embryonic day 10.5 (E10.5). Chd7(Gt/+) male and female mice are viable, small, and exhibit variable degrees of head-bobbing and circling, consistent with vestibular dysfunction. Paint-filling of E16.5 heterozygous inner ears revealed defects of the semicircular canals. The pattern of beta-galactosidase activity in Chd7(Gt/+) embryos mimics Chd7 mRNA expression in wild-type embryos, confirming the fidelity of the lacZ reporter. We observed tissue-specific beta-galactosidase in the E12.5 and E14.5 Chd7(Gt/+) brain, pituitary, ear, heart, and craniofacial structures, indicating survival of Chd7(Gt/+) cells in CHARGE-relevant organs. These studies demonstrate the utility of Chd7(Gt) as a reporter-tagged loss-of-function allele for future studies exploring developmental mechanisms of Chd7 deficiency.
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Affiliation(s)
- Elizabeth A Hurd
- Department of Pediatrics, The University of Michigan Medical Center, Ann Arbor, Michigan 48109-0652, USA
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7
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Hall JC, Chang DC, Dolezelova E. Principles and problems revolving around rhythm-related genetic variants. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2007; 72:215-232. [PMID: 18419279 DOI: 10.1101/sqb.2007.72.039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Much of what is known about the regulation of circadian rhythms has stemmed from the induction, recognition, or manufacture of genetic variants. Such investigations have been especially salient in chronobiological analyses of Drosophila. Many starting points for elucidation of rhythmic processes operating in this insect entailed the isolation of mutants or the design of engineered gene modifications. Various features of the principles and practices associated with the genetic approach toward understanding clock functions, and chronobiologically related ones, are discussed from perspectives that are largely genetic as such, although intertwined with certain neurogenetic and molecular-genetic concerns when appropriate. Key themes in this treatment connect with the power and problems associated with multiply mutant forms of rhythm-related genes, with the opportunistic or problematical aspects of multigenic variants that are in play (sometimes surprisingly), and with a question as to how forceful chronogenetic inferences have been in terms of elucidating the mechanisms of circadian pacemaking.
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Affiliation(s)
- J C Hall
- Department of Biology, Brandeis University, Waltham, Massachusetts 02454, USA
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Abstract
The study of human behavioural and psychiatric disorders benefits from the development of genetic models in mice and other organisms. Mouse mutants allow one to investigate the molecular basis of disease progression and to develop novel therapies. The number of potential mouse models is increasing dramatically through the implementation of mutagenesis screens for aberrant behavioural phenotypes. The alkylating agent N-ethyl-N-nitrosourea ENU is the mutagen of choice in these screens as it induces mutations at a very high rate. Progeny of chemically-mutagenised animals are screened either in systematic high-throughput test batteries or in specific low-throughput tests. Both approaches have been highly successful with large numbers of novel loci being identified and characterised. Many mutant lines are available for general research with phenotypes and genetic map positions on public websites. Of the mutant genes characterised, the majority have contributed to our knowledge of gene function in physiology and disease. The 'mutagenesis screening' approach continues to evolve through the design of new phenotyping strategies. The development of modifier screens in mice shows promise in the elucidation of complex phenotypes whereas the use of mutagenesis in combination with pharmacological agents targets specific neurochemical systems. Finally, the systematic screening approach has demonstrated that mutations are likely to affect more than one biological process.
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Affiliation(s)
- Sofia I H Godinho
- MRC Mammalian Genetics Unit, Harwell, Didcot, Oxfordshire OX11 0RD, UK
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9
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Bosman EA, Penn AC, Ambrose JC, Kettleborough R, Stemple DL, Steel KP. Multiple mutations in mouse Chd7 provide models for CHARGE syndrome. Hum Mol Genet 2005; 14:3463-76. [PMID: 16207732 DOI: 10.1093/hmg/ddi375] [Citation(s) in RCA: 166] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Mouse ENU mutagenesis programmes have yielded a series of independent mutations on proximal chromosome 4 leading to dominant head-bobbing and circling behaviour due to truncations of the lateral semicircular canal of the inner ear. Here, we report the identification of mutations in the Chd7 gene in nine of these mutant alleles including six nonsense and three splice site mutations. The human CHD7 gene is known to be involved in CHARGE syndrome, which also shows inner ear malformations and a variety of other features with varying penetrance and appears to be due to frequent de novo mutation. We found widespread expression of Chd7 in early development of the mouse in organs affected in CHARGE syndrome including eye, olfactory epithelium, inner ear and vascular system. Closer inspection of heterozygous mutant mice revealed a range of defects with reduced penetrance, such as cleft palate, choanal atresia, septal defects of the heart, haemorrhages, prenatal death, vulva and clitoral defects and keratoconjunctivitis sicca. Many of these defects mimic the features of CHARGE syndrome. There were no obvious features of the gene that might make it more mutable than other genes. We conclude that the large number of mouse mutants and human de novo mutations may be due to the combination of the Chd7 gene being a large target and the fact that many heterozygous carriers of the mutations are viable individuals with a readily detectable phenotype.
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Affiliation(s)
- Erika A Bosman
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK
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10
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Mrosovsky N, Hattar S. Diurnal mice (Mus musculus) and other examples of temporal niche switching. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2005; 191:1011-24. [PMID: 16163543 DOI: 10.1007/s00359-005-0017-1] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2005] [Revised: 05/23/2005] [Accepted: 05/24/2005] [Indexed: 11/25/2022]
Abstract
Examples are presented of nocturnal animals becoming diurnal or vice versa as a result of mutations, genetic manipulations, or brain lesions. Understanding these cases could give insight into mechanisms employed when switches of temporal niche occur as part of the life cycle, or in response to circumstances such as availability of food. A two-process account of niche switching is advocated, involving both a change in clock-controlled outputs and a change in the direct response to light (i.e. masking). An emerging theme from this review is the suggestion that retinal inputs have a greater role in switching than suspected previously.
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Affiliation(s)
- N Mrosovsky
- Department of Zoology, University of Toronto, ON, M5S3G5, Canada.
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11
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Pinto LH, Vitaterna MH, Siepka SM, Shimomura K, Lumayag S, Baker M, Fenner D, Mullins RF, Sheffield VC, Stone EM, Heffron E, Takahashi JS. Results from screening over 9000 mutation-bearing mice for defects in the electroretinogram and appearance of the fundus. Vision Res 2005; 44:3335-45. [PMID: 15536001 PMCID: PMC3756145 DOI: 10.1016/j.visres.2004.07.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2004] [Revised: 07/14/2004] [Indexed: 10/26/2022]
Abstract
Random mutagenesis combined with phenotypic screening using carefully crafted functional tests has successfully led to the discovery of genes that are essential for a number of functions. This approach does not require prior knowledge of the identity of the genes that are involved and is a way to ascribe function to the nearly 6000 genes for which knowledge of the DNA sequence has been inadequate to determine the function of the gene product. In an effort to identify genes involved in the visual system via this approach, we have tested over 9000 first and third generation offspring of mice treated with the mutagen N-ethyl-N-nitrosourea (ENU) for visual defects, as evidenced by abnormalities in the electroretinogram and appearance of the fundus. We identified 61 putative mutations with this procedure and outline the steps needed to identify the affected genes.
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Affiliation(s)
- Lawrence H Pinto
- Department of Neurobiology and Physiology and Center for Functional Genomics, Northwestern University, 2205 Tech Drive, Hogan Hall 2-140, Evanston, IL 60208, USA.
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12
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Yu Q, Shen Y, Chatterjee B, Siegfried BH, Leatherbury L, Rosenthal J, Lucas JF, Wessels A, Spurney CF, Wu YJ, Kirby ML, Svenson K, Lo CW. ENU induced mutations causing congenital cardiovascular anomalies. Development 2004; 131:6211-23. [PMID: 15548583 DOI: 10.1242/dev.01543] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We used non-invasive high frequency ultrasound to screen N-ethyl-N-nitrosourea mutagenized mouse fetuses for congenital cardiovascular anomalies. We ultrasound scanned 7546 mouse fetuses from 262 mutagenized families, and identified 124 families with cardiovascular defects. Represented were most of the major congenital cardiovascular anomalies seen clinically. The ENU-induced mutations in several families were mapped using polymorphic microsatellite DNA markers. One family with forelimb anomalies and ventricular septal defects, phenotypes similar to Holt-Oram syndrome, and one family with transposition of the great arteries and heart situs anomalies were mapped to different regions of mouse chromosome 4. A third mutation causing persistent truncus arteriosus and craniofacial defects, phenotypes reminiscent of DiGeorge syndrome, was mapped to mouse chromosome 2. We note that mouse chromosomes 4 and 2 do not contain Tbx5 or Tbx1, genes previously linked to Holt-Oram and DiGeorge syndromes, respectively. In two other families, the ENU-induced mutation was identified--Sema3CL605P was associated with persistent truncus arteriosus with interrupted aortic arch, and the Gja1W45X connexin43 mutation caused conotruncal malformation and coronary aneurysms. Although our screen was designed as a recessive screen, a number of the mutations showed cardiovascular phenotypes in both heterozygote and homozygote animals. These studies show the efficacy of ENU mutagenesis and high-throughput ultrasound phenotyping in recovering mutations causing a wide spectrum of congenital heart defects. These ENU-induced mutations hold promise in yielding new insights into the genetic basis for human congenital heart disease.
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Affiliation(s)
- Qing Yu
- Laboratory of Developmental Biology, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892-8019, USA
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Redlin U, Cooper HM, Mrosovsky N. Increased masking response to light after ablation of the visual cortex in mice. Brain Res 2003; 965:1-8. [PMID: 12591114 DOI: 10.1016/s0006-8993(02)03844-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mice are known to suppress their wheel running when given a pulse of light in the night (masking response). The amount of suppression can be quantified; the response varies with the level of irradiance used during the light pulse. After ablation of the visual cortex, mice suppressed their activity more than sham-operated controls. In addition, the lesioned animals responded to lower levels of irradiance than controls. It is suggested that the visual cortex is not needed for the suppression of locomotor activity after a light pulse. Nevertheless it exerts an inhibitory influence on the masking response to light mediated by an irradiance detection system. When this inhibition is removed, even though pattern vision is lost, masking responses to ambient level of light are enhanced.
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Affiliation(s)
- Uwe Redlin
- Department of Animal Physiology, Biological Institute, University of Stuttgart, D-70550, Stuttgart, Germany.
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14
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Sollars PJ, Ogilvie MD, Rea MA, Pickard GE. 5-HT1B receptor knockout mice exhibit an enhanced response to constant light. J Biol Rhythms 2002; 17:428-37. [PMID: 12375619 DOI: 10.1177/074873002237137] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Serotonin (5-HT) can act presynaptically at 5-HT1B receptors on retinal terminals in the suprachiasmatic nucleus (SCN) to inhibit glutamate release, thereby modulating the effects of light on circadian behavior. 5-HT1B receptor agonists (1) inhibit light-induced phase shifts of circadian activity rhythms, (2) attenuate light-induced Fos expression in the SCN, and (3) reduce the amplitude of optic nerve-evoked excitatory postsynaptic currents in SCN neurons in vitro. To determine whether functional disruption of the 5-HT1B presynaptic receptors would result in an amplified response of the SCN to light, the period (tau) of the circadian rhythm of wheel-running activity was estimated under several different conditions in 5-HT1B receptor knockout (KO) mice and genetically matched wild-type animals. Under constant light (LL) conditions, the tau of 5-HT1B receptor KO mice was significantly greater than the tau of wild-type mice. A quantitative analysis of the wheel-running activity revealed no differences between wild-type and KO mice in either total activity or the temporal distribution of activity under LL conditions, suggesting that the observed increase in tau was not a function of reduced activity. Under constant dark conditions, the period of the circadian rhythm of wheel-running activity of wild-type and 5-HT1B receptor KO mice was similar. In addition, no differences were noted between wild-type and 5-HT1B receptor KO mice in the rate of reentrainment to a 6 h phase advance in the 12:12 light:dark cycle or in phase shifts in response to a 10 min light pulse presented at circadian time 16. The enhanced response of the SCN circadian clock of the 5-HT1B receptor KO mice to LL conditions is consistent with the hypothesis that the endogenous activation of 5-HT1B presynaptic receptors modulates circadian behavior by attenuating photic input to the SCN.
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Affiliation(s)
- Patricia J Sollars
- Department of Anatomy and Neurobiology, Colorado State University, Fort Collins 80523-1670, USA.
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Fuji JI, Fukuda R, Imoto F, Ooshima Y. New behavioral mutant rat exhibiting circling behavior (clx) controlled by a sex-linked recessive gene. Congenit Anom (Kyoto) 2002; 42:187-93. [PMID: 12502898 DOI: 10.1111/j.1741-4520.2002.tb00892.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
A male rat showing intermittent circling behavior was discovered among the Jcl:Wistar rats in our laboratories, and among its backcross offspring individuals showing the same behavior were found. The abnormalities in these animals were characterized by intermittent circling behavior (walking and/or running in circles) and head tossing with the neck twisted. No abnormalities were observed in fertility, delivery or pup mortality. The results of mating experiments indicated that the circling behavior phenotype is controlled by a single sex-linked recessive gene, and the mutant was named "circling behavior linked to X-chromosome (gene symbol: clx)." This circling behavior mutant is considered to be different from the previously reported mutants, the behavior in all of which has been found to be autosomally inherited. Sib-mating is continuing to produce an inbred strain with this newly discovered circling behavior mutant gene.
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Affiliation(s)
- Jun-Ichiro Fuji
- Hikari Branch, Drug Safety Research Laboratories, Pharmaceutical Research Division, Takeda Chemical Industries, Ltd., Hikari, Yamaguchi 743-8502, Japan.
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16
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Kiernan AE, Erven A, Voegeling S, Peters J, Nolan P, Hunter J, Bacon Y, Steel KP, Brown SDM, Guénet JL. ENU mutagenesis reveals a highly mutable locus on mouse Chromosome 4 that affects ear morphogenesis. Mamm Genome 2002; 13:142-8. [PMID: 11919684 DOI: 10.1007/bf02684018] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2001] [Accepted: 11/01/2001] [Indexed: 12/22/2022]
Abstract
Chemical mutagenesis followed by screening for abnormal phenotypes in the mouse holds much promise as a method for revealing gene function. This method is particularly well-suited for discovering genes involved in hearing or balance function, as these defects are relatively easy to screen for in the mouse. We report here the inner ear abnormalities and genetic localization of seven new dominant mutations created by ENU mutagenesis. All seven mutant stocks were identified because of circling and/or head-weaving behavior, which is an indication of balance dysfunction. Investigation of the inner ears of the seven mutant stocks revealed very similar lateral and posterior semicircular canal defects. Studies of the development of the canals in one mutant stock revealed that the affected canals showed reduced outgrowth and delayed canal fusion. Physiological studies performed in one mutant stock showed raised average compound-action-potential thresholds of approximately 10-20 dB sound pressure level (SPL) (depending on frequency), indicating a mild hearing impairment, although scanning electron microscopy performed in several of the mutant stocks revealed no obvious structural defects in the organ of Corti. All seven mutations mapped to the proximal portion of Chromosome (Chr) 4, near the centromere. On the basis of their similar phenotype and map location, we suggest that the seven mutant genes may be allelic and represent a highly mutable locus on Chr 4 that may be particularly susceptible to ENU-induced mutation on the BALB/c genetic background.
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Affiliation(s)
- Amy E Kiernan
- MRC Institute of Hearing Research, University Park, Nottingham, NG7 2RD, UK
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17
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Hara H, Nolan PM, Scott MO, Bucan M, Wakayama Y, Fischbeck KH. Running endurance abnormality in mdx mice. Muscle Nerve 2002; 25:207-11. [PMID: 11870688 DOI: 10.1002/mus.10023] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The mdx mouse lacks dystrophin and has histological features of Duchenne muscular dystrophy but little weakness in the first year of life. We report here an early deficit in voluntary wheel running, as assayed with a computerized wheel. All mdx mice showed an intermittent running pattern, in contrast to the continuous running seen in controls. The average continuous running time differed significantly between mdx and control mice at all ages tested (5-21 weeks). This assay is noninvasive, has the advantage of unbiased automatic data collection, and should be useful for quantifying the mdx deficit in therapeutic studies.
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Affiliation(s)
- Hajime Hara
- Division of Neurology, Department of Medicine, Showa University, Fujigaoka Hospital, 1-30, Fujigaoka, Aobaku, Yokohamashi 227-0043, Japan.
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18
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Abstract
With the completion of the human genome, sequence analysis of gene function will move into the center of future genome research. One of the key strategies for studying gene function involves the genetic dissection of biological processes in animal models. Mouse mutants are of particular importance for the analysis of disease pathogenesis and transgenic techniques, and gene targeting have become routine tools. Recently, phenotype-driven strategies using chemical mutagenesis have been the target of increasing interest. In this review, the current state of ENU mutagenesis and its application as a systematic tool of genome analysis are examined.
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Affiliation(s)
- R Balling
- German Research Centre for Biotechnology, D-38124 Braunschweig, Germany.
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19
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Laemle LK, Ottenweller JE. The relationship between circadian rhythmicity and vasoactive intestinal polypeptide in the suprachiasmatic nucleus of congenitally anophthalmic mice. Brain Res 2001; 917:105-11. [PMID: 11602234 DOI: 10.1016/s0006-8993(01)02929-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
To date, the search for the clock component that is both necessary and sufficient for generation of circadian rhythms has relied primarily on experimental interventions such as lesions and transplantation of fetal SCN. While these approaches have been fruitful, lesions disrupt adjacent host tissue and fiber pathways, and donor tissue is likewise subject to trauma during harvest and transplantation. The current investigation has used congenitally anophthalmic (eyeless) mice to ask whether VIP-IR SCN neurons are necessary and sufficient for generation of circadian rhythms. In this animal model, arrhythmic mice occur naturally, together with their rhythmic littermates. We have combined recording of wheel-running activity with light microscopic immunocytochemistry for vasoactive intestinal polypeptide (VIP) and cytoarchitectural analysis of the suprachiasmatic nuclei (SCN) in rhythmic and arrhythmic anophthalmic mice. Our data provide the first definitive evidence that the presence of VIP neurons in the SCN is not sufficient for generation of circadian locomotor rhythms.
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Affiliation(s)
- L K Laemle
- Department of Anatomy, Cell Biology and Injury Sciences, UMDNJ-New Jersey Medical School, 185 South Orange Avenue, Newark, NJ 07103, USA.
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20
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Alavizadeh A, Kiernan AE, Nolan P, Lo C, Steel KP, Bucan M. The Wheels mutation in the mouse causes vascular, hindbrain, and inner ear defects. Dev Biol 2001; 234:244-60. [PMID: 11356033 DOI: 10.1006/dbio.2001.0241] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In a screen for mouse mutations with dominant behavioral anomalies, we identified Wheels, a mutation associated with circling and hyperactivity in heterozygotes and embryonic lethality in homozygotes. Mutant Wheels embryos die at E10.5-E11.5 and exhibit a host of morphological anomalies which include growth retardation and anomalies in vascular and hindbrain development. The latter includes perturbation of rhombomeric boundaries as detected by Krox20 and Hoxb1. PECAM-1 staining of embryos revealed normal formation of the primary vascular plexus. However, subsequent stages of branching and remodeling do not proceed normally in the yolk sac and in the embryo proper. To obtain insights into the circling behavior, we examined development of the inner ear by paint-filling of membranous labyrinths of Whl/+ embryos. This analysis revealed smaller posterior and lateral semicircular canal primordia and a delay in the canal fusion process at E12.5. By E13.5, the lateral canal was truncated and the posterior canal was small or absent altogether. Marker analysis revealed an early molecular phenotype in heterozygous embryos characterized by perturbed expression of Bmp4 and Msx1 in prospective lateral and posterior cristae at E11.5. We have constructed a genetic and radiation hybrid map of the centromeric portion of mouse Chromosome 4 across the Wheels region and refined the position of the Wheels locus to the approximately 1.1-cM region between D4Mit104 and D4Mit181. We have placed the locus encoding Epha7, in the Wheels candidate region; however, further analysis showed no mutations in the Epha7-coding region and no detectable changes in mRNA expression pattern. In summary, our findings indicate that Wheels, a gene which is essential for the survival of the embryo, may link diverse processes involved in vascular, hindbrain, and inner ear development.
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Affiliation(s)
- A Alavizadeh
- Department of Psychiatry and Genetics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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21
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Herzog ED, Grace MS, Harrer C, Williamson J, Shinohara K, Block GD. The role of Clock in the developmental expression of neuropeptides in the suprachiasmatic nucleus. J Comp Neurol 2000; 424:86-98. [PMID: 10888741 DOI: 10.1002/1096-9861(20000814)424:1<86::aid-cne7>3.0.co;2-w] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The suprachiasmatic nucleus (SCN) is the dominant circadian pacemaker in mammals. To understand better the ontogeny of mouse SCN and the role of the pacemaker in peptide expression, the authors examined the distribution of cells that were immunoreactive for vasopressin (AVP) or vasoactive intestinal polypeptide (VIP) in wild type and Clock mutant mice at two developmental stages. Clock homozygous mice failed to show the dramatic increase in the number of VIP-immunoreactive (VIP-ir) neurons from postnatal day 6 (P6) to P30 that was found in the SCN of wild type mice. The number of AVP-ir neurons was relatively constant in the postnatal SCN but was significantly reduced in Clock/Clock mice. The effects of the Clock mutation varied with position in the SCN for both peptides. Densitometry of immunolabeled brains indicated that the Clock mutation reduced AVP expression specifically in the SCN and not in other brain areas. The SCN did not significantly change shape or size with age or Clock genotype. Taken together, these results indicate that the neonatal mouse SCN has its full complement of cells, some of which are not yet mature in their neuropeptide content. Furthermore, the observation that the Clock mutation appears to act on a subset of AVP and VIP cells suggests heterogeneity within these cell classes in the SCN.
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Affiliation(s)
- E D Herzog
- Department of Biology, National Science Foundation Center for Biological Timing, University of Virginia, Charlottesville, Virginia 22903, USA.
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22
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Abstract
Masking and entrainment are two different processes that result in rhythms in physiology and behavior. Considering its functional importance, lamentably little study has been devoted to masking compared to that lavished on entrainment. This paper discusses the origin and definition of terminology (positive and negative masking, paradoxical masking) and methods of quantifying masking. How masking is scored can greatly influence the interpretation of results.
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Affiliation(s)
- N Mrosovsky
- Department of Zoology, University of Toronto, Ontario, Canada.
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23
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Matsuura A, Ohno T, Matsushima T, Namikawa T, Ishikawa A. Delayed development of reflexes and hyperactive locomotion in the spontaneous mutant "waltzing" of the musk shrew, Suncus murinus. Exp Anim 1999; 48:191-7. [PMID: 10480024 DOI: 10.1538/expanim.48.191] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The autosomal recessive mutation waltzing (wz), displaying abnormal circling and head-shaking behavior, has previously been reported in the musk shrew (Suncus murinus). Postnatal development of reflexes and locomotor patterns in an open arena were examined in wz/wz mutant shrews. The wz/wz shrews showed extreme developmental delays in surface-righting reflex and negative geotaxis until 10-16 days after birth, but both reflexes eventually recovered to the levels of +/wz normal. Nevertheless, the wz/wz adults exhibited bi-directional circling behavior 59 times, head-tossing behavior 22 times and horizontal head-shaking behavior 6 times more frequent than in the +/wz controls. Although the wz/wz adult shrews were extremely hyperactive with daily spontaneous locomotor activity exceeding 4-7 times control shrew activity, they appeared to have a normal circadian rhythm. This shrew mutant may therefore be useful as a model for hyperactivity syndromes in humans.
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Affiliation(s)
- A Matsuura
- Laboratory of Animal Genetics, Graduate School of Bioagricultural Sciences, Nagoya University, Japan
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24
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Abstract
Significant progress has been made in sequencing the genomes of several model organisms, and efforts are now underway to complete the sequencing of the human genome. In parallel with this effort, new approaches are being developed for the elucidation of the functional content of the human genome. The mouse will have an important role in this phase of the genome project as a model system. In this review we discuss and compare classical genetic approaches to gene function-phenotype-based mutagenesis screens aimed at the establishment of a large collection of single gene mutations affecting a wide range of phenotypic traits in the mouse. Whereas large scale genome-wide screens that are directed at the identification of all loci contributing to a specific phenotype may be impractical, region-specific saturation screens that provide mutations within a delimited chromosomal region are a feasible alternative. Region-specific screens in the mouse can be performed in only two generations by combining high-efficiency chemical mutagenesis with deletion complexes generated using embryonic stem (ES) cells. The ability to create and analyze deletion complexes rapidly, as well as to map novel chemically-induced mutations within these complexes, will facilitate systematic functional analysis of the mouse genome and corresponding gene sequences in humans. Furthermore, as the extent of the mouse genome sequencing effort is still uncertain, we underscore a necessity to direct sequencing efforts to those chromosomal regions that are targets for extensive mutagenesis screens.
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Affiliation(s)
- J Schimenti
- The Jackson Laboratory, Bar Harbor, Maine 04609 USA
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25
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Abstract
The worldwide effort to completely sequence the human and mouse genome will be accomplished within the next years. The focus of current activities within the framework of human genome research is mainly on the assembly of high resolution genetic and physical maps and genomic sequencing. Cloning of new genes is getting more easy using those maps. Nevertheless, it is necessary to work on a systematic analysis of gene function. Results obtained from these efforts will be of enormous value for future biological and biomedical research. However, even the complete sequence will not in all cases reveal the molecular and cellular role of the different genes. Therefore, the next phase of the Human Genome Project will have at its core the functional analysis of genes. Those genes relevant for the diagnosis, prevention and therapy of human diseases are of particular interest. Looking at the history of life sciences, mutants have been the most important tool to obtain insight into the biological function of genes. The mouse is the model of choice for the study of inherited diseases in man. In order to meet the requirements for functional human genome analysis, we need a large number of mouse mutants similar to the collection of mutants available for other model organisms such as flys and worms. To fully apply the power of genetics, multiple alleles of the same gene such as hypomorphs or hypermorphs are required. Efficient production of mouse mutants showing specific phenotypes can be achieved by the use of ethylnitrosourea (ENU). ENU is the most powerful mutagen known and we currently see a renaissance of ENU mutagenesis. The application of ENU mutagenesis is reviewed and discussed in the context of a new era of functional genomics.
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Affiliation(s)
- M Hrabé de Angelis
- Institute of Mammalian Genetics, GSF Research Center for Environment and Health, 85764 Neuherberg, Germany
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26
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Abstract
The suprachiasmatic nuclei (SCN) of the anterior hypothalamus contain the master circadian pacemaker in mammals. On the occasion of the 25th anniversary of the discovery of the SCN as the circadian clock, Charles A. Czeisler and Steven M. Reppert organized a meeting to review milestones and recent developments in the study of the SCN. The discovery that the SCN contain tissue necessary for generation of circadian rhythmicity was established by lesion studies published in 1972. The second phase of study demonstrated unequivocally that the SCN contain an autonomous circadian pacemaker. The principal studies in this period showed the presence of metabolic and electrical activity rhythms in the SCN in vivo and progressed to studies showing that the SCN maintain rhythmicity in vitro, demonstrating that the transplanted SCN can restore circadian function following destruction of the host SCN and ultimately showing that single SCN "clock cells" exhibit independent rhythms in firing rate. The third phase of study, aimed at identifying the biochemical and molecular mechanisms responsible for rhythmicity within the SCN, has begun with the identification of circadian mutants (tau mutant hamsters and Clock mutant mice) and the isolation of the Clock gene. This report traces the important steps forward in our understanding of the suprachiasmatic circadian clock by recounting the information presented at the SCN Silver Anniversary Celebration.
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Affiliation(s)
- D R Weaver
- Laboratory of Developmental Chronobiology, Pediatric Service, Massachusetts General Hospital, Boston 02114, USA
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27
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Nolan PM, Kapfhamer D, Bućan M. Random mutagenesis screen for dominant behavioral mutations in mice. Methods 1997; 13:379-95. [PMID: 9480783 DOI: 10.1006/meth.1997.0545] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Large-scale mutagenesis and screening for altered phenotypes have been used effectively in many (lower) model organisms to identify mutations in genes that control biological processes. In the mouse, the cost of maintaining the large breeding colonies necessary to screen for recessive mutations makes it important to consider alternate approaches such as region-specific saturation mutagenesis or screening for mutations with a dominant mode of inheritance. In this article, a pilot screen for (semi)dominant visible and behavioral mutations in the mouse induced by a potent chemical mutagen, N-ethyl-N-nitrosourea (ENU), is described. An efficient protocol for ENU mutagenesis and strain-specific differences in the effect of mutagen on the sterility period and long-term survival are reported. In addition to a description of the screen for abnormal circadian wheel running activity that was used previously, the suitability of a high-throughput screen of mutagenized progeny in the Porsolt swim test, used to test the efficacy of antidepressant agents, and in the prepulse inhibition of the acoustic startle response, used to detect anomalies in sensorimotor gating, is tested. By demonstrating strain specific differences and prescreening 100 G1 progeny of mutagenized males, the feasibility of using these behavioral assays for a large-scale screen is illustrated. In this review, details of a mutagenesis screen for behavioral abnormalities are described and issues important in the initial characterization of novel ENU-induced mutations are considered.
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Affiliation(s)
- P M Nolan
- Center for Neurobiology and Behavior, University of Pennsylvania School of Medicine, Philadelphia 19104, USA
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28
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Affiliation(s)
- W J Schwartz
- Department of Neurology, University of Massachusetts Medical School, Worcester 01655, USA
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