1
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Rath MF. Homeobox gene-encoded transcription factors in development and mature circadian function of the rodent pineal gland. J Pineal Res 2024; 76:e12950. [PMID: 38558122 DOI: 10.1111/jpi.12950] [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: 10/03/2023] [Revised: 02/15/2024] [Accepted: 03/11/2024] [Indexed: 04/04/2024]
Abstract
Homeobox genes encode transcription factors that are widely known to control developmental processes. This is also the case in the pineal gland, a neuroendocrine brain structure devoted to nighttime synthesis of the hormone melatonin. Thus, in accordance with high prenatal gene expression, knockout studies have identified a specific set of homeobox genes that are essential for development of the pineal gland. However, as a special feature of the pineal gland, homeobox gene expression persists into adulthood, and gene product abundance exhibits 24 h circadian rhythms. Recent lines of evidence show that some homeobox genes even control expression of enzymes catalyzing melatonin synthesis. We here review current knowledge of homeobox genes in the rodent pineal gland and suggest a model for dual functions of homeobox gene-encoded transcription factors in developmental and circadian mature neuroendocrine function.
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Affiliation(s)
- Martin F Rath
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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2
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Mattern KMJ, Blancas-Velázquez AS, Ngo MT, Bille S, Hertz H, Bering T, Rath MF. The ISL LIM-homeobox 2 transcription factor is negatively regulated by circadian adrenergic signaling to repress the expression of Aanat in pinealocytes of the rat pineal gland. J Pineal Res 2023; 75:e12905. [PMID: 37649242 DOI: 10.1111/jpi.12905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 07/19/2023] [Accepted: 08/07/2023] [Indexed: 09/01/2023]
Abstract
Melatonin is synthesized in the pineal gland during nighttime in response to nocturnal increase in the activity of the enzyme aralkylamine N-acetyltransferase (AANAT), the transcription of which is modulated by several homeodomain transcription factors. Recent work suggests that the homeodomain transcription factor ISL LIM homeobox 2 (ISL2) is expressed in the pineal gland, but its role is currently unknown. With the purpose of identifying the mechanisms that control pineal expression of Isl2 and the possible function of Isl2 in circadian pineal biology, we report that Isl2 is specifically expressed in the pinealocytes of the rat pineal gland. Its expression exhibits a 24 h rhythm with high transcript and protein levels during the day and a trough in the second half of the night. This rhythm persists in darkness, and lesion studies reveal that it requires intact function of the suprachiasmatic nuclei, suggesting intrinsic circadian regulation. In vivo and in vitro experiments show that pineal Isl2 expression is repressed by adrenergic signaling acting via cyclic AMP; further, Isl2 is negatively regulated by the nocturnal transcription factor cone-rod homeobox. During development, pineal Isl2 expression is detectable from embryonic day 19, preceding Aanat by several days. In vitro knockdown of Isl2 is accompanied by an increase in Aanat transcript levels suggesting that ISL2 represses its daytime expression. Thus, rhythmic expression of ISL2 in pinealocytes is under the control of the suprachiasmatic nucleus acting via adrenergic signaling in the gland to repress nocturnal expression, while ISL2 itself negatively regulates daytime pineal expression of Aanat and thereby suggestively enhances the circadian rhythm in melatonin synthesis.
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Affiliation(s)
- Kuno M-J Mattern
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Aurea S Blancas-Velázquez
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mikaella T Ngo
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Signe Bille
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Henrik Hertz
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Tenna Bering
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Martin F Rath
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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3
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Muñoz EM, Martínez Cerdeño V. Editorial: Transcription regulation - Brain development and homeostasis - A finely tuned and orchestrated scenario in physiology and pathology, volume II. Front Mol Neurosci 2023; 16:1280573. [PMID: 37736114 PMCID: PMC10509287 DOI: 10.3389/fnmol.2023.1280573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Accepted: 08/25/2023] [Indexed: 09/23/2023] Open
Affiliation(s)
- Estela M. Muñoz
- Institute of Histology and Embryology of Mendoza (IHEM), National University of Cuyo (UNCuyo), National Scientific and Technical Research Council (CONICET), Mendoza, Argentina
| | - Verónica Martínez Cerdeño
- Department of Pathology and Laboratory Medicine, Institute for Pediatric Regenerative Medicine, Shriners Hospitals for Children of Northern California, and MIND Institute at the UC Davis Medical Center, University of California Davis School of Medicine, Sacramento, CA, United States
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4
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An ultrastructural study of the deep pineal gland of the Sprague Dawley rat using transmission and serial block face scanning electron microscopy: cell types, barriers, and innervation. Cell Tissue Res 2022; 389:531-546. [PMID: 35737105 DOI: 10.1007/s00441-022-03654-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Accepted: 06/10/2022] [Indexed: 11/02/2022]
Abstract
The morphology of the deep pineal gland of the Sprague Dawley rat was investigated by serial block face scanning electron microscopy. Cells were three-dimensionally (3-D) reconstructed using the software Fiji TrackEM. The deep pineal gland consisted of 2-5 layers of electron-lucent pinealocytes, with a euchromatic nucleus, endowed with one or two processes. Laterally, the deep pineal merged with the habenula and the stria medullaris thalami, via an intermediate area containing cells with more electron-dense cytoplasm and an indented nucleus with heterochromatin. Neither nerve terminals nor capillaries were observed in the deep pineal itself but present in the intermediate parts of the gland. The deep pineal was in contact with the third ventricle via the pineal and suprahabenular recesses. The ependymal lining in these recesses was an epithelium connected by tight junctions between their lateral cell membranes. Several intraventricular nerve terminals were in contact with the ependyma. 3-D reconstructions showed the ependymal cells endowed with long slender process penetrating the underlying pineal parenchyma. Few "tanocyte-like" ependymal cells, endowed with a process, reaching the subarachnoid space on the inferior surface of the deep pineal were observed. In addition, pinealocyte and astrocyte processes, often connected by gap junctions, bordered the inferior surface. In summary, the rat deep pineal gland is a neuroendocrine structure connected to the habenula. We here report specialized ependymal cells that might transmit signals from the cerebrospinal fluid to the deep pineal parenchyma and a "trans-pineal tanocyte-like cell" that connects the ventricular system with the subarachnoid space.
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5
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Rath MF, Møller M. Radiochemical In Situ Hybridization in Developmental Studies of the Pineal Gland. Methods Mol Biol 2022; 2550:75-84. [PMID: 36180679 DOI: 10.1007/978-1-0716-2593-4_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Radiochemical in situ hybridization enables detection of gene expression in small areas of the brain, such as the developing pineal gland in rodents. The method combines determination of spatial and temporal gene expression profiles with semiquantitative analyses. We here describe the procedure of radiochemical in situ hybridization on the developing rat pineal gland ranging from preparation of fetal tissue for in situ hybridization to principles of quantification.
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Affiliation(s)
| | - Morten Møller
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
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6
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Blancas-Velazquez AS, Rath MF. siRNA-Mediated Downregulation of Gene Expression in Cultured Rat Pineal Cells. Methods Mol Biol 2022; 2550:113-121. [PMID: 36180684 DOI: 10.1007/978-1-0716-2593-4_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Suspension primary cultures of rat pineal cells have been used for decades to determine biochemical regulatory mechanisms of pineal melatonin synthesis, but more recently, RNA interference technology has made the study of the role of specific genes in this melatonin-proficient model system possible. We here present a protocol for preparing rat pineal cell cultures and efficiently knock down gene expression by use of synthetic siRNA.
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Madhani SI, Klein DC, Muñoz EM, Savastano LE. Surgical Techniques and Nuances for Superior Cervical Ganglionectomy and Decentralization in Rats. Methods Mol Biol 2022; 2550:53-62. [PMID: 36180677 DOI: 10.1007/978-1-0716-2593-4_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The sympathetic nervous system has been implicated in various physiological and pathological processes, including regulation of homeostatic functions, maintenance of the circadian rhythms, and neuronal disruption and recovery after injury. Of special interest is focus on the role of the superior cervical ganglion (SCG) in regulating the daily changes in pineal function. Removal of the superior cervical ganglion (SCGx) and decentralization have served as valuable microsurgical models to investigate the effects of surgical denervation on this gland or organ. In this chapter, we offer information about methodologies for performing SCGx along with decentralization and denervation procedures, including details about recommended equipment as well as tips that can improve these techniques.
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Affiliation(s)
- Sarosh Irfan Madhani
- Department of Neurosurgery, University of California, San Francisco, San Francisco, CA, USA
| | - David C Klein
- Section on Neuroendocrinology, Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Estela M Muñoz
- Laboratory of Neurobiology: Section of Chronobiology, Institute of Histology and Embryology of Mendoza (IHEM), National University of Cuyo, National Scientific and Technical Research Council (CONICET), Mendoza, Argentina
| | - Luis E Savastano
- Department of Neurosurgery, University of California, San Francisco, San Francisco, CA, USA.
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Hertz H, Blancas-Velazquez AS, Rath MF. The role of homeobox gene-encoded transcription factors in regulation of phototransduction: Implementing the primary pinealocyte culture as a photoreceptor model. J Pineal Res 2021; 71:e12753. [PMID: 34129741 DOI: 10.1111/jpi.12753] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 06/14/2021] [Accepted: 06/14/2021] [Indexed: 10/21/2022]
Abstract
Homeobox genes encode transcription factors controlling development; however, a number of homeobox genes are expressed postnatally specifically in melatonin-producing pinealocytes of the pineal gland and photoreceptors of the retina along with transcripts devoted to melatonin synthesis and phototransduction. Homeobox genes regulate melatonin synthesis in pinealocytes, but some homeobox genes also seem to be involved in regulation of retinal phototransduction. Due to the lack of photoreceptor models, we here introduce the rat pinealocyte culture as an in vitro model for studying retinal phototransduction. Systematic qPCR analyses were performed on the rat retina and pineal gland in 24 hour in vivo series and on primary cultures of rat pinealocytes: All homeobox genes and melatonin synthesis components, as well as nine out of ten phototransduction genes, were readily detectable in all three experimental settings, confirming molecular similarity between cultured pinealocytes and in vivo retinal tissue. 24 hours circadian expression was mostly confined to transcripts in the pineal gland, including a novel rhythm in arrestin (Sag). Individual knockdown of the homeobox genes orthodenticle homeobox 2 (Otx2), cone-rod homeobox (Crx) and LIM homeobox 4 (Lhx4) in pinealocyte culture using siRNA resulted in specific downregulation of transcripts representing all levels of phototransduction; thus, all phototransduction genes studied in culture were affected by one or several siRNA treatments. Histological colocalization of homeobox and phototransduction transcripts in the rat retinal photoreceptor was confirmed by RNAscope in situ hybridization, thus suggesting that homeobox gene-encoded transcription factors control postnatal expression of phototransduction genes in the retinal photoreceptor.
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Affiliation(s)
- Henrik Hertz
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Martin Fredensborg Rath
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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9
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Carstensen MB, Hertz H, Bering T, Møller M, Rohde K, Klein DC, Coon SL, Rath MF. Circadian regulation and molecular role of the Bsx homeobox gene in the adult pineal gland. J Pineal Res 2020; 68:e12629. [PMID: 31808568 PMCID: PMC7122731 DOI: 10.1111/jpi.12629] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 11/29/2019] [Accepted: 11/30/2019] [Indexed: 11/28/2022]
Abstract
The pineal gland is a neuroendocrine organ responsible for production of the nocturnal hormone melatonin. A specific set of homeobox gene-encoded transcription factors govern pineal development, and some are expressed in adulthood. The brain-specific homeobox gene (Bsx) falls into both categories. We here examined regulation and function of Bsx in the mature pineal gland of the rat. We report that Bsx is expressed from prenatal stages into adulthood, where Bsx transcripts are localized in the melatonin-synthesizing pinealocytes, as revealed by RNAscope in situ hybridization. Bsx transcripts were also detected in the adult human pineal gland. In the rat pineal gland, Bsx was found to exhibit a 10-fold circadian rhythm with a peak at night. By combining in vivo adrenergic stimulation and surgical denervation of the gland in the rat with in vitro stimulation and transcriptional inhibition in cultured pinealocytes, we show that rhythmic expression of Bsx is controlled at the transcriptional level by the sympathetic neural input to the gland acting via adrenergic stimulation with cyclic AMP as a second messenger. siRNA-mediated knockdown (>80% reduction) in pinealocyte cultures revealed Bsx to be a negative regulator of other pineal homeobox genes, including paired box 4 (Pax4), but no effect on genes encoding melatonin-synthesizing enzymes was detected. RNA sequencing analysis performed on siRNA-treated pinealocytes further revealed that downstream target genes of Bsx are mainly involved in developmental processes. Thus, rhythmic Bsx expression seems to govern other developmental regulators in the mature pineal gland.
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Affiliation(s)
- Mikkel B Carstensen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Henrik Hertz
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Tenna Bering
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Morten Møller
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kristian Rohde
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - David C Klein
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Steven L Coon
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Martin F Rath
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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10
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Hertz H, Carstensen MB, Bering T, Rohde K, Møller M, Granau AM, Coon SL, Klein DC, Rath MF. The Lhx4 homeobox transcript in the rat pineal gland: Adrenergic regulation and impact on transcripts encoding melatonin-synthesizing enzymes. J Pineal Res 2020; 68:e12616. [PMID: 31609018 PMCID: PMC8408918 DOI: 10.1111/jpi.12616] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 10/07/2019] [Accepted: 10/08/2019] [Indexed: 12/23/2022]
Abstract
Homeobox genes generally encode transcription factors involved in regulating developmental processes. In the pineal gland, a brain structure devoted to nocturnal melatonin synthesis, a number of homeobox genes are also expressed postnatally; among these is the LIM homeobox 4 gene (Lhx4). We here report that Lhx4 is specifically expressed in the postnatal pineal gland of rats and humans. Circadian analyses revealed a fourfold rhythm in Lhx4 expression in the rat pineal gland, with rhythmic expression detectable from postnatal day 10. Pineal Lhx4 expression was confirmed to be positively driven by adrenergic signaling, as evidenced by in vivo modulation of Lhx4 expression by pharmacological (isoprenaline injection) and surgical (superior cervical ganglionectomy) interventions. In cultured pinealocytes, Lhx4 expression was upregulated by cyclic AMP, a second messenger of norepinephrine. By use of RNAscope technology, Lhx4 transcripts were found to be exclusively localized in melatonin-synthesizing pinealocytes. This prompted us to investigate the possible role of Lhx4 in regulation of melatonin-producing enzymes. By use of siRNA technology, we knocked down Lhx4 by 95% in cultured pinealocytes; this caused a reduction in transcripts encoding the melatonin-producing enzyme arylalkylamine N-acetyl transferase (Aanat). Screening the transcriptome of siRNA-treated pinealocytes by RNAseq revealed a significant impact of Lhx4 on the phototransduction pathway and on transcripts involved in development of the nervous system and photoreceptors. These data suggest that rhythmic expression of Lhx4 in the pineal gland is controlled via an adrenergic-cyclic AMP mechanism and that Lhx4 acts to promote nocturnal melatonin synthesis.
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Affiliation(s)
- Henrik Hertz
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mikkel B Carstensen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Tenna Bering
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kristian Rohde
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Morten Møller
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Agnete M Granau
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Steven L Coon
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - David C Klein
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Martin F Rath
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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11
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Yang Y, Zhou R, Li W, Liu Y, Zhang Y, Ao H, Li H, Li K. Dynamic Transcriptome Analysis Reveals Potential Long Non-coding RNAs Governing Postnatal Pineal Development in Pig. Front Genet 2019; 10:409. [PMID: 31130986 PMCID: PMC6510172 DOI: 10.3389/fgene.2019.00409] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 04/15/2019] [Indexed: 12/25/2022] Open
Abstract
Postnatal development and maturation of pineal gland is a highly dynamic period of tissue remodeling and phenotype maintenance, which is genetically controlled by programmed gene expression regulations. However, limited molecular characterization, particularly regarding long noncoding RNAs (lncRNA), is available for postnatal pineal at a whole transcriptome level. The present study first characterized the comprehensive pineal transcriptome profiles using strand-specific RNA-seq to illustrate the dynamic mRNA/lncRNA expression at three developmental stages (infancy, puberty, and adulthood). The results showed that 21,448 mRNAs and 8,166 novel lncRNAs were expressed in pig postnatal pineal gland. Among these genes, 3,573 mRNAs and 851 lncRNAs, including the 5-hydroxytryptamine receptors, exhibited significant dynamic regulation along maturation process, while the expression of homeobox genes didn't show significant differences. Gene Ontology analysis revealed that the differentially expressed genes (DEGs) were significantly enriched in ion transport and synaptic transmission, highlighting the critical role of calcium signaling in postnatal pineal development. Additionally, co-expression analysis revealed the DEGs could be grouped into 12 clusters with distinct expression patterns. Many differential lncRNAs were functionally enriched in co-expressed clusters of genes related to ion transport, transcription regulation, DNA binding, and visual perception. Our study first provided an overview of postnatal pineal transcriptome dynamics in pig and demonstrated that dynamic lncRNA regulation of developmental transitions impact pineal physiology.
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Affiliation(s)
- Yalan Yang
- Guangdong Provincial Key Laboratory of Animal Molecular Design and Precise Breeding, School of Life Sciences and Engineering, Foshan University, Foshan, China
| | - Rong Zhou
- Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Wentong Li
- Guangdong Provincial Key Laboratory of Animal Molecular Design and Precise Breeding, School of Life Sciences and Engineering, Foshan University, Foshan, China
- Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Ying Liu
- Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yanmin Zhang
- Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Hong Ao
- Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Hua Li
- Guangdong Provincial Key Laboratory of Animal Molecular Design and Precise Breeding, School of Life Sciences and Engineering, Foshan University, Foshan, China
| | - Kui Li
- Guangdong Provincial Key Laboratory of Animal Molecular Design and Precise Breeding, School of Life Sciences and Engineering, Foshan University, Foshan, China
- Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
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12
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Rohde K, Hertz H, Rath MF. Homeobox genes in melatonin-producing pinealocytes: Otx2 and Crx act to promote hormone synthesis in the mature rat pineal gland. J Pineal Res 2019; 66:e12567. [PMID: 30803008 DOI: 10.1111/jpi.12567] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 02/15/2019] [Accepted: 02/20/2019] [Indexed: 02/03/2023]
Abstract
Homeobox genes encode transcription factors that regulate developmental processes; however, in the pineal gland, a neuroendocrine organ responsible for nocturnal melatonin synthesis, expression of the homeobox genes Otx2 (orthodenticle homeobox 2) and Crx (cone-rod homeobox) persists postnatally. We here show that OTX2 and CRX are exclusively present in melatonin-producing pinealocytes of the rat pineal gland. To understand the roles of Otx2 and Crx in the mature pineal gland, we used siRNA technology in cultured rat pinealocytes with the nocturnal situation mimicked by adding norepinephrine to the culture media. siRNA-induced knockdown of Otx2 was found to reduce expression levels of the enzymes involved in melatonin synthesis at both transcript and protein levels. Similar results were obtained when knocking down Crx. Knocking down Otx2 and Crx simultaneously produced an even larger reduction in both transcript and protein levels of the melatonin-producing enzymes and also reduced the levels of melatonin released to the culture media. These results suggest that Otx2 and Crx, both alone and in combination, act to control pineal melatonin synthesis.
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Affiliation(s)
- Kristian Rohde
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Henrik Hertz
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Martin F Rath
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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13
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Di Nardo AA, Fuchs J, Joshi RL, Moya KL, Prochiantz A. The Physiology of Homeoprotein Transduction. Physiol Rev 2019; 98:1943-1982. [PMID: 30067157 DOI: 10.1152/physrev.00018.2017] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The homeoprotein family comprises ~300 transcription factors and was long seen as primarily involved in developmental programs through cell autonomous regulation. However, recent evidence reveals that many of these factors are also expressed in the adult where they exert physiological functions not yet fully deciphered. Furthermore, the DNA-binding domain of most homeoproteins contains two signal sequences allowing their secretion and internalization, thus intercellular transfer. This review focuses on this new-found signaling in cell migration, axon guidance, and cerebral cortex physiological homeostasis and speculates on how it may play important roles in early arealization of the neuroepithelium. It also describes the use of homeoproteins as therapeutic proteins in mouse models of diseases affecting the central nervous system, in particular Parkinson disease and glaucoma.
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Affiliation(s)
- Ariel A Di Nardo
- Centre for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS UMR 7241, INSERM U1050, Labex MemoLife, PSL Research University , Paris , France
| | - Julia Fuchs
- Centre for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS UMR 7241, INSERM U1050, Labex MemoLife, PSL Research University , Paris , France
| | - Rajiv L Joshi
- Centre for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS UMR 7241, INSERM U1050, Labex MemoLife, PSL Research University , Paris , France
| | - Kenneth L Moya
- Centre for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS UMR 7241, INSERM U1050, Labex MemoLife, PSL Research University , Paris , France
| | - Alain Prochiantz
- Centre for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS UMR 7241, INSERM U1050, Labex MemoLife, PSL Research University , Paris , France
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14
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Signaling within the pineal gland: A parallelism with the central nervous system. Semin Cell Dev Biol 2018; 95:151-159. [PMID: 30502386 DOI: 10.1016/j.semcdb.2018.11.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 11/15/2018] [Accepted: 11/27/2018] [Indexed: 12/22/2022]
Abstract
The pineal gland (PG) derives from the neural tube, like the rest of the central nervous system (CNS). The PG is specialized in synthesizing and secreting melatonin in a circadian fashion. The nocturnal elevation of melatonin is a highly conserved feature among species which proves its importance in nature. Here, we review a limited set of intrinsic and extrinsic regulatory elements that have been shown or proposed to influence the PG's melatonin production, as well as pineal ontogeny and homeostasis. Intrinsic regulators include the transcription factors CREB, Pax6 and NeuroD1. In addition, microglia within the PG participate as extrinsic regulators of these functions. We further discuss how these same elements work in other parts of the CNS, and note similarities and differences to their roles in the PG. Since the PG is a relatively well-defined and highly specialized organ within the CNS, we suggest that applying this comparative approach to additional PG regulators may be a useful tool for understanding complex areas of the brain, as well as the influence of the PG in both health and disease, including circadian functions and disorders.
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15
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Bering T, Carstensen MB, Wörtwein G, Weikop P, Rath MF. The Circadian Oscillator of the Cerebral Cortex: Molecular, Biochemical and Behavioral Effects of Deleting the Arntl Clock Gene in Cortical Neurons. Cereb Cortex 2018; 28:644-657. [PMID: 28052921 DOI: 10.1093/cercor/bhw406] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 12/20/2016] [Indexed: 11/13/2022] Open
Abstract
A molecular circadian oscillator resides in neurons of the cerebral cortex, but its role is unknown. Using the Cre-LoxP method, we have here abolished the core clock gene Arntl in those neurons. This mouse represents the first model carrying a deletion of a circadian clock component specifically in an extrahypothalamic cell type of the brain. Molecular analyses of clock gene expression in the cerebral cortex of the Arntl conditional knockout mouse revealed disrupted circadian expression profiles, whereas clock gene expression in the suprachiasmatic nucleus was still rhythmic, thus showing that Arntl is required for normal function of the cortical circadian oscillator. Daily rhythms in running activity and temperature were not influenced, whereas the resynchronization response to experimental jet-lag exhibited minor though significant differences between genotypes. The tail-suspension test revealed significantly prolonged immobility periods in the knockout mouse indicative of a depressive-like behavioral state. This phenotype was accompanied by reduced norepinephrine levels in the cerebral cortex. Our data show that Arntl is required for normal cortical clock function and further give reason to suspect that the circadian oscillator of the cerebral cortex is involved in regulating both circadian biology and mood-related behavior and biochemistry.
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Affiliation(s)
- Tenna Bering
- Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
- Laboratory of Neuropsychiatry, Psychiatric Center Copenhagen, Mental Health Services of the Capital Region of Denmark, DK-2100 Copenhagen, Denmark
| | - Mikkel Bloss Carstensen
- Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Gitta Wörtwein
- Department of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1014 Copenhagen, Denmark
| | - Pia Weikop
- Laboratory of Neuropsychiatry, Psychiatric Center Copenhagen, Mental Health Services of the Capital Region of Denmark, DK-2100 Copenhagen, Denmark
| | - Martin Fredensborg Rath
- Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
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Musser JM, Arendt D. Loss and gain of cone types in vertebrate ciliary photoreceptor evolution. Dev Biol 2017; 431:26-35. [DOI: 10.1016/j.ydbio.2017.08.038] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Revised: 08/28/2017] [Accepted: 08/30/2017] [Indexed: 01/09/2023]
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Rohde K, Bering T, Furukawa T, Rath MF. A modulatory role of the Rax
homeobox gene in mature pineal gland function: Investigating the photoneuroendocrine circadian system of a Rax
conditional knockout mouse. J Neurochem 2017; 143:100-111. [DOI: 10.1111/jnc.14120] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 06/09/2017] [Accepted: 06/25/2017] [Indexed: 01/19/2023]
Affiliation(s)
- Kristian Rohde
- Department of Neuroscience; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Tenna Bering
- Department of Neuroscience; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
- Laboratory of Neuropsychiatry; Psychiatric Center Copenhagen; Mental Health Services of the Capital Region of Denmark; Copenhagen Denmark
| | - Takahisa Furukawa
- Laboratory for Molecular and Developmental Biology; Institute for Protein Research; Osaka University; Suita Osaka Japan
| | - Martin Fredensborg Rath
- Department of Neuroscience; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
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Rath MF, Coon SL, Amaral FG, Weller JL, Møller M, Klein DC. Melatonin Synthesis: Acetylserotonin O-Methyltransferase (ASMT) Is Strongly Expressed in a Subpopulation of Pinealocytes in the Male Rat Pineal Gland. Endocrinology 2016; 157:2028-40. [PMID: 26950199 PMCID: PMC4870883 DOI: 10.1210/en.2015-1888] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The rat pineal gland has been extensively used in studies of melatonin synthesis. However, the cellular localization of melatonin synthesis in this species has not been investigated. Here we focus on the localization of melatonin synthesis using immunohistochemical methods to detect the last enzyme in melatonin synthesis, acetylserotonin O-methyltransferase (ASMT), and in situ hybridization techniques to study transcripts encoding ASMT and two other enzymes in melatonin synthesis, tryptophan hydroxylase (TPH)-1 and aralkylamine N-acetyltransferase. In sections of the rat pineal gland, marked cell-to-cell differences were found in ASMT immunostaining intensity and in the abundance of Tph1, Aanat, and Asmt transcripts. ASMT immunoreactivity was localized to the cytoplasm in pinealocytes in the parenchyma of the superficial pineal gland, and immunopositive pinealocytes were also detected in the pineal stalk and in the deep pineal gland. ASMT was found to inconsistently colocalize with S-antigen, a widely used pinealocyte marker; this colocalization was seen in cells throughout the pineal complex and also in displaced pinealocyte-like cells of the medial habenular nucleus. Inconsistent colocalization between ASMT and TPH protein was also detected in the pineal gland. ASMT protein was not detected in extraepithalamic parts of the central nervous system or in peripheral tissues. The findings in this report are of special interest because they provide reason to suspect that melatonin synthesis varies significantly among individual pinealocytes.
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Affiliation(s)
- Martin F Rath
- Department of Neuroscience and Pharmacology (M.F.R., M.M.), Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark; and Section on Neuroendocrinology (M.F.R., S.L.C., F.G.A., J.L.W., D.C.K.), Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892
| | - Steven L Coon
- Department of Neuroscience and Pharmacology (M.F.R., M.M.), Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark; and Section on Neuroendocrinology (M.F.R., S.L.C., F.G.A., J.L.W., D.C.K.), Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892
| | - Fernanda G Amaral
- Department of Neuroscience and Pharmacology (M.F.R., M.M.), Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark; and Section on Neuroendocrinology (M.F.R., S.L.C., F.G.A., J.L.W., D.C.K.), Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892
| | - Joan L Weller
- Department of Neuroscience and Pharmacology (M.F.R., M.M.), Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark; and Section on Neuroendocrinology (M.F.R., S.L.C., F.G.A., J.L.W., D.C.K.), Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892
| | - Morten Møller
- Department of Neuroscience and Pharmacology (M.F.R., M.M.), Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark; and Section on Neuroendocrinology (M.F.R., S.L.C., F.G.A., J.L.W., D.C.K.), Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892
| | - David C Klein
- Department of Neuroscience and Pharmacology (M.F.R., M.M.), Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark; and Section on Neuroendocrinology (M.F.R., S.L.C., F.G.A., J.L.W., D.C.K.), Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892
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Castro AE, Benitez SG, Farias Altamirano LE, Savastano LE, Patterson SI, Muñoz EM. Expression and cellular localization of the transcription factor NeuroD1 in the developing and adult rat pineal gland. J Pineal Res 2015; 58:439-51. [PMID: 25752781 DOI: 10.1111/jpi.12228] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 03/04/2015] [Indexed: 12/13/2022]
Abstract
Circadian rhythms govern many aspects of mammalian physiology. The daily pattern of melatonin synthesis and secretion is one of the classic examples of circadian oscillations. It is mediated by a class of neuroendocrine cells known as pinealocytes which are not yet fully defined. An established method to evaluate functional and cytological characters is through the expression of lineage-specific transcriptional regulators. NeuroD1 is a basic helix-loop-helix transcription factor involved in the specification and maintenance of both endocrine and neuronal phenotypes. We have previously described developmental and adult regulation of NeuroD1 mRNA in the rodent pineal gland. However, the transcript levels were not influenced by the elimination of sympathetic input, suggesting that any rhythmicity of NeuroD1 might be found downstream of transcription. Here, we describe NeuroD1 protein expression and cellular localization in the rat pineal gland during development and the daily cycle. In embryonic and perinatal stages, protein expression follows the mRNA pattern and is predominantly nuclear. Thereafter, NeuroD1 is mostly found in pinealocyte nuclei in the early part of the night and in cytoplasm during the day, a rhythm maintained into adulthood. Additionally, nocturnal nuclear NeuroD1 levels are reduced after sympathetic disruption, an effect mimicked by the in vivo administration of α- and β-adrenoceptor blockers. NeuroD1 phosphorylation at two sites, Ser(274) and Ser(336) , associates with nuclear localization in pinealocytes. These data suggest that NeuroD1 influences pineal phenotype both during development and adulthood, in an autonomic and phosphorylation-dependent manner.
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Affiliation(s)
- Analía E Castro
- Laboratory of Neurobiology: Chronobiology Section, Institute of Histology and Embryology of Mendoza (IHEM-CONICET), School of Medicine, National University of Cuyo, Mendoza, Argentina
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Hooper CM, Hawes SM, Kees UR, Gottardo NG, Dallas PB. Gene expression analyses of the spatio-temporal relationships of human medulloblastoma subgroups during early human neurogenesis. PLoS One 2014; 9:e112909. [PMID: 25412507 PMCID: PMC4239019 DOI: 10.1371/journal.pone.0112909] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 09/10/2014] [Indexed: 12/31/2022] Open
Abstract
Medulloblastoma is the most common form of malignant paediatric brain tumour and is the leading cause of childhood cancer related mortality. The four molecular subgroups of medulloblastoma that have been identified – WNT, SHH, Group 3 and Group 4 - have molecular and topographical characteristics suggestive of different cells of origin. Definitive identification of the cell(s) of origin of the medulloblastoma subgroups, particularly the poorer prognosis Group 3 and Group 4 medulloblastoma, is critical to understand the pathogenesis of the disease, and ultimately for the development of more effective treatment options. To address this issue, the gene expression profiles of normal human neural tissues and cell types representing a broad neuro-developmental continuum, were compared to those of two independent cohorts of primary human medulloblastoma specimens. Clustering, co-expression network, and gene expression analyses revealed that WNT and SHH medulloblastoma may be derived from distinct neural stem cell populations during early embryonic development, while the transcriptional profiles of Group 3 and Group 4 medulloblastoma resemble cerebellar granule neuron precursors at weeks 10–15 and 20–30 of embryogenesis, respectively. Our data indicate that Group 3 medulloblastoma may arise through abnormal neuronal differentiation, whereas deregulation of synaptic pruning-associated apoptosis may be driving Group 4 tumorigenesis. Overall, these data provide significant new insight into the spatio-temporal relationships and molecular pathogenesis of the human medulloblastoma subgroups, and provide an important framework for the development of more refined model systems, and ultimately improved therapeutic strategies.
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Affiliation(s)
- Cornelia M. Hooper
- Brain Tumour Research Program, Telethon Kids Institute, University of Western Australia, Subiaco, Western Australia, Australia
- Centre of Excellence in Computational Systems Biology, ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, Perth, Western Australia, Australia
| | - Susan M. Hawes
- Monash Institute of Medical Research, Monash University, Clayton, Victoria, Australia
| | - Ursula R. Kees
- Division of Children's Leukaemia and Cancer Research, Telethon Kids Institute, University of Western Australia, Subiaco, Western Australia, Australia
| | - Nicholas G. Gottardo
- Brain Tumour Research Program, Telethon Kids Institute, University of Western Australia, Subiaco, Western Australia, Australia
- Department of Paediatric Oncology and Haematology, Princess Margaret Hospital for Children, Subiaco, Western Australia, Australia
| | - Peter B. Dallas
- Brain Tumour Research Program, Telethon Kids Institute, University of Western Australia, Subiaco, Western Australia, Australia
- * E-mail:
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Rohde K, Rovsing L, Ho AK, Møller M, Rath MF. Circadian dynamics of the cone-rod homeobox (CRX) transcription factor in the rat pineal gland and its role in regulation of arylalkylamine N-acetyltransferase (AANAT). Endocrinology 2014; 155:2966-75. [PMID: 24877634 DOI: 10.1210/en.2014-1232] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The cone-rod homeobox (Crx) gene encodes a transcription factor in the retina and pineal gland. Crx deficiency influences the pineal transcriptome, including a reduced expression of arylalkylamine N-acetyltransferase (Aanat), a key enzyme in nocturnal pineal melatonin production. However, previous functional studies on pineal Crx have been performed in melatonin-deficient mice. In this study, we have investigated the role of Crx in the melatonin-proficient rat pineal gland. The current study shows that pineal Crx transcript levels exhibit a circadian rhythm with a peak in the middle of the night, which is transferred into daily changes in CRX protein. The study further shows that the sympathetic innervation of the pineal gland controls the Crx rhythm. By use of adenovirus-mediated short hairpin RNA gene knockdown targeting Crx mRNA in primary rat pinealocyte cell culture, we here show that intact levels of Crx mRNA are required to obtain high levels of Aanat expression, whereas overexpression of Crx induces Aanat transcription in vitro. This regulatory function of Crx is further supported by circadian analysis of Aanat in the pineal gland of the Crx-knockout mouse. Our data indicate that the rhythmic nature of pineal CRX protein may directly modulate the daily profile of Aanat expression by inducing nighttime expression of this enzyme, thus facilitating nocturnal melatonin synthesis in addition to its role in ensuring a correct tissue distribution of Aanat expression.
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Affiliation(s)
- Kristian Rohde
- Department of Neuroscience and Pharmacology (K.R., L.R., M.M., M.F.R.), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; and Department of Physiology (K.R., A.K.H.), Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
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Anatomical, molecular and pathological consideration of the circumventricular organs. Neurochirurgie 2014; 61:90-100. [PMID: 24974365 DOI: 10.1016/j.neuchi.2013.04.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Revised: 04/15/2013] [Accepted: 04/23/2013] [Indexed: 01/25/2023]
Abstract
BACKGROUND AND PURPOSE Circumventricular organs (CVOs) are a diverse group of specialised structures characterized by peculiar vascular and position around the third and fourth ventricles of the brain. In humans, these organs are present during the fetal period and some become vestigial after birth. Some, such as the pineal gland (PG), subcommissural organ (SCO) and organum vasculosum of the lamina terminalis (OVLT), which are located around the third ventricle, might be the site of origin of periventricular tumours. In contrast to humans, CVOs are present in the adult rat and can be dissected by laser capture microdissection (LCM). METHODS In this study, we used LCM and microarrays to analyse the transcriptomes of three CVOs, the SCO, the subfornical organ (SFO) and the PG and the third ventricle ependyma of the adult rat, in order to better characterise these organs at the molecular level. Furthermore, an immunohistochemical study of Claudin-3 (CLDN3), a membrane protein involved in forming cellular tight junctions, was performed at the level of the SCO. RESULTS This study highlighted some potentially new or already described specific markers of these structures as Erbb2 and Col11a1 in ependyma, Epcam and CLDN3 in the SCO, Ren1 and Slc22a3 in the SFO and Tph, Anat and Asmt in the PG. Moreover, we found that CLDN3 expression was restricted to the apical pole of ependymocytes in the SCO.
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Rath MF, Rovsing L, Møller M. Circadian oscillators in the mouse brain: molecular clock components in the neocortex and cerebellar cortex. Cell Tissue Res 2014; 357:743-55. [PMID: 24842045 DOI: 10.1007/s00441-014-1878-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 03/25/2014] [Indexed: 01/27/2023]
Abstract
The circadian timekeeper of the mammalian brain resides in the suprachiasmatic nucleus of the hypothalamus (SCN), and is characterized by rhythmic expression of a set of clock genes with specific 24-h daily profiles. An increasing amount of data suggests that additional circadian oscillators residing outside the SCN have the capacity to generate peripheral circadian rhythms. We have recently shown the presence of SCN-controlled oscillators in the neocortex and cerebellum of the rat. The function of these peripheral brain clocks is unknown, and elucidating this could involve mice with conditional cell-specific clock gene deletions. This prompted us to analyze the molecular clockwork of the mouse neocortex and cerebellum in detail. Here, by use of in situ hybridization and quantitative RT-PCR, we show that clock genes are expressed in all six layers of the neocortex and the Purkinje and granular cell layers of the cerebellar cortex of the mouse brain. Among these, Per1, Per2, Cry1, Arntl, and Nr1d1 exhibit circadian rhythms suggesting that local running circadian oscillators reside within neurons of the mouse neocortex and cerebellar cortex. The temporal expression profiles of clock genes are similar in the neocortex and cerebellum, but they are delayed by 5 h as compared to the SCN, suggestively reflecting a master-slave relationship between the SCN and extra-hypothalamic oscillators. Furthermore, ARNTL protein products are detectable in neurons of the mouse neocortex and cerebellum, as revealed by immunohistochemistry. These findings give reason to further pursue the physiological significance of circadian oscillators in the mouse neocortex and cerebellum.
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Affiliation(s)
- Martin F Rath
- Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Rigshospitalet 6102, Blegdamsvej 9, Copenhagen, DK-2100, Denmark,
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Homeobox genes and melatonin synthesis: regulatory roles of the cone-rod homeobox transcription factor in the rodent pineal gland. BIOMED RESEARCH INTERNATIONAL 2014; 2014:946075. [PMID: 24877149 PMCID: PMC4022116 DOI: 10.1155/2014/946075] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Accepted: 04/07/2014] [Indexed: 01/20/2023]
Abstract
Nocturnal synthesis of melatonin in the pineal gland is controlled by a circadian rhythm in arylalkylamine N-acetyltransferase (AANAT) enzyme activity. In the rodent, Aanat gene expression displays a marked circadian rhythm; release of norepinephrine in the gland at night causes a cAMP-based induction of Aanat transcription. However, additional transcriptional control mechanisms exist. Homeobox genes, which are generally known to encode transcription factors controlling developmental processes, are also expressed in the mature rodent pineal gland. Among these, the cone-rod homeobox (CRX) transcription factor is believed to control pineal-specific Aanat expression. Based on recent advances in our understanding of Crx in the rodent pineal gland, we here suggest that homeobox genes play a role in adult pineal physiology both by ensuring pineal-specific Aanat expression and by facilitating cAMP response element-based circadian melatonin production.
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The Lhx9 homeobox gene controls pineal gland development and prevents postnatal hydrocephalus. Brain Struct Funct 2014; 220:1497-509. [PMID: 24647753 DOI: 10.1007/s00429-014-0740-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Accepted: 02/19/2014] [Indexed: 12/16/2022]
Abstract
Lhx9 is a member of the LIM homeobox gene family. It is expressed during mammalian embryogenesis in the brain including the pineal gland. Deletion of Lhx9 results in sterility due to failure of gonadal development. The current study was initiated to investigate Lhx9 biology in the pineal gland. Lhx9 is highly expressed in the developing pineal gland of the rat with transcript abundance peaking early in development; transcript levels decrease postnatally to nearly undetectable levels in the adult, a temporal pattern that is generally similar to that reported for Lhx9 expression in other brain regions. Studies with C57BL/6J Lhx9(-/-) mutant mice revealed marked alterations in brain and pineal development. Specifically, the superficial pineal gland is hypoplastic, being reduced to a small cluster of pinealocytes surrounded by meningeal and vascular tissue. The deep pineal gland and the pineal stalk are also reduced in size. Although the brains of neonatal Lhx9(-/-) mutant mice appear normal, severe hydrocephalus develops in about 70% of the Lhx9(-/-) mice at 5-8 weeks of age; these observations are the first to document that deletion of Lhx9 results in hydrocephalus and as such indicate that Lhx9 contributes to the maintenance of normal brain structure. Whereas hydrocephalus is absent in neonatal Lhx9(-/-)mutant mice, the neonatal pineal gland in these animals is hypoplastic. Accordingly, it appears that Lhx9 is essential for early development of the mammalian pineal gland and that this effect is not secondary to hydrocephalus.
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Manila A, Mariangela N, Libero L, Francesca G, Romana BF, Felice G. Is CRX protein a useful marker in differential diagnosis of tumors of the pineal region? Pediatr Dev Pathol 2014; 17:85-8. [PMID: 24555912 DOI: 10.2350/13-06-1346-oa.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The cone-rod homeobox (CRX) is a gene that belongs to the member of the orthodenticle homeobox (Otx) family, with important function in development and differentiation of retinal and pineal cells. Moreover, CRX appears to be specifically expressed in pineal tumors and retinoblastomas. We performed an immunohistochemical study on 91 pediatric and adult central nervous system tumors, plus 2 normal brain samples. Our results demonstrated that CRX is expressed not only in pineal parenchymal tumors and retinoblastoma, but also in a some medulloblastomas and supratentorial primitive neuroectodermal tumors. None of the glial tumors screened were positive for CRX. In conclusion, CRX could be useful in surgical neuropathology for the differential diagnosis of pineal region tumors, in particular to discriminate pineal tumors from glial tumors.
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Affiliation(s)
- Antonelli Manila
- 1 Department of Radiological, Oncological and Anatomo-Pathological Sciences, Sapienza University Viale Regina Elena 324, 00161 Rome, Italy
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Changes in Otx2 and parvalbumin immunoreactivity in the superior colliculus in the platelet-derived growth factor receptor-β knockout mice. BIOMED RESEARCH INTERNATIONAL 2013; 2013:848265. [PMID: 24319691 PMCID: PMC3844215 DOI: 10.1155/2013/848265] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 09/30/2013] [Indexed: 12/11/2022]
Abstract
The superior colliculus (SC), a relay nucleus in the subcortical visual pathways, is implicated in socioemotional behaviors. Homeoprotein Otx2 and β subunit of receptors of platelet-derived growth factor (PDGFR-β) have been suggested to play an important role in development of the visual system and development and maturation of GABAergic neurons. Although PDGFR-β-knockout (KO) mice displayed socio-emotional deficits associated with parvalbumin (PV-)immunoreactive (IR) neurons, their anatomical bases in the SC were unknown. In the present study, Otx2 and PV-immunolabeling in the adult mouse SC were investigated in the PDGFR-β KO mice. Although there were no differences in distribution patterns of Otx2 and PV-IR cells between the wild type and PDGFR-β KO mice, the mean numbers of both of the Otx2- and PV-IR cells were significantly reduced in the PDGFR-β KO mice. Furthermore, average diameters of Otx2- and PV-IR cells were significantly reduced in the PDGFR-β KO mice. These findings suggest that PDGFR-β plays a critical role in the functional development of the SC through its effects on Otx2- and PV-IR cells, provided specific roles of Otx2 protein and PV-IR cells in the development of SC neurons and visual information processing, respectively.
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Choroid-plexus-derived Otx2 homeoprotein constrains adult cortical plasticity. Cell Rep 2013; 3:1815-23. [PMID: 23770240 DOI: 10.1016/j.celrep.2013.05.014] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 03/26/2013] [Accepted: 05/09/2013] [Indexed: 01/27/2023] Open
Abstract
Brain plasticity is often restricted to critical periods in early life. Here, we show that a key regulator of this process in the visual cortex, Otx2 homeoprotein, is synthesized and secreted globally from the choroid plexus. Consequently, Otx2 is maintained in selected GABA cells unexpectedly throughout the mature forebrain. Genetic disruption of choroid-expressed Otx2 impacts these distant circuits and in the primary visual cortex reopens binocular plasticity to restore vision in amblyopic mice. The potential to regulate adult cortical plasticity through the choroid plexus underscores the importance of this structure in brain physiology and offers therapeutic approaches to recovery from a broad range of neurodevelopmental disorders.
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Rath MF, Rohde K, Klein DC, Møller M. Homeobox genes in the rodent pineal gland: roles in development and phenotype maintenance. Neurochem Res 2013; 38:1100-12. [PMID: 23076630 PMCID: PMC3570627 DOI: 10.1007/s11064-012-0906-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 09/19/2012] [Accepted: 10/04/2012] [Indexed: 12/12/2022]
Abstract
The pineal gland is a neuroendocrine gland responsible for nocturnal synthesis of melatonin. During early development of the rodent pineal gland from the roof of the diencephalon, homeobox genes of the orthodenticle homeobox (Otx)- and paired box (Pax)-families are expressed and are essential for normal pineal development consistent with the well-established role that homeobox genes play in developmental processes. However, the pineal gland appears to be unusual because strong homeobox gene expression persists in the pineal gland of the adult brain. Accordingly, in addition to developmental functions, homeobox genes appear to be key regulators in postnatal phenotype maintenance in this tissue. In this paper, we review ontogenetic and phylogenetic aspects of pineal development and recent progress in understanding the involvement of homebox genes in rodent pineal development and adult function. A working model is proposed for understanding the sequential action of homeobox genes in controlling development and mature circadian function of the mammalian pinealocyte based on knowledge from detailed developmental and daily gene expression analyses in rats, the pineal phenotypes of homebox gene-deficient mice and studies on development of the retinal photoreceptor; the pinealocyte and retinal photoreceptor share features not seen in other tissues and are likely to have evolved from the same ancestral photodetector cell.
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Affiliation(s)
- Martin F Rath
- Department of Neuroscience and Pharmacology, Panum Institute 24.2, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, Copenhagen 2200, Denmark.
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Schang AL, Bleux C, Chenut MC, Ngô-Muller V, Quérat B, Jeanny JC, Counis R, Cohen-Tannoudji J, Laverrière JN. Identification and analysis of two novel sites of rat GnRH receptor gene promoter activity: the pineal gland and retina. Neuroendocrinology 2013; 97:115-31. [PMID: 22414758 DOI: 10.1159/000337661] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 02/28/2012] [Indexed: 11/19/2022]
Abstract
BACKGROUND AND AIMS In mammals, activation of pituitary GnRH receptor (GnRHR) by hypothalamic GnRH increases the synthesis and secretion of LH and FSH, which, in turn, regulate gonadal functions. However, GnRHR gene (Gnrhr) expression is not restricted to the pituitary. METHODS To gain insight into the extrapituitary expression of Gnrhr, a transgenic mouse model that expresses the human placental alkaline phosphatase reporter gene driven by the rat Gnrhr promoter was created. RESULTS This study shows that the rat Gnrhr promoter is operative in two functionally related organs, the pineal gland, as early as embryonic day (E) 13.5, and the retina where activity was only detected at E17.5. Accordingly, Gnrhr mRNA were present in both tissues. Transcription factors known to regulate Gnrhr promoter activity such as the LIM homeodomain factors LHX3 and ISL1 were also detected in the retina. Furthermore, transient transfection studies in CHO and gonadotrope cells revealed that OTX2, a major transcription factor in both pineal and retina cell differentiation, is able to activate the Gnrhr promoter together with either CREB or PROP1, depending on the cell context. CONCLUSION Rather than using alternate promoters, Gnrhr expression is directed to diverse cell lineages through specific associations of transcription factors acting on distinct response elements along the same promoter. These data open new avenues regarding GnRH-mediated control of seasonal and circadian rhythms in reproductive physiology.
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Affiliation(s)
- Anne-Laure Schang
- Université Paris Diderot Paris 7, Sorbonne Paris Cité, Biologie Fonctionnelle et Adaptative, EAC CNRS 4413, Physiologie de l'Axe Gonadotrope, Paris, France
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Karlsen AS, Rath MF, Rohde K, Toft T, Møller M. Developmental and diurnal expression of the synaptosomal-associated protein 25 (Snap25) in the rat pineal gland. Neurochem Res 2012; 38:1219-28. [PMID: 23135794 DOI: 10.1007/s11064-012-0918-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 09/19/2012] [Accepted: 10/25/2012] [Indexed: 11/24/2022]
Abstract
Snap25 (synaptosomal-associated protein) is a 25 kDa protein, belonging to the SNARE-family (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) of proteins, essential for synaptic and secretory vesicle exocytosis. Snap25 has by immunohistochemistry been demonstrated in the rat pineal gland but the biological importance of this is unknown. In this study, we demonstrate a high expression of mRNA encoding Snap25 in all parts of the rat pineal complex, the superficial-, and deep-pineal gland, as well as in the pineal stalk. Snap25 showed a low pineal expression during embryonic stages with a strong increase in expression levels just after birth. The expression showed no day/night variations. Neither removal of the sympathetic input to the pineal gland by superior cervical ganglionectomy nor bilateral decentralization of the superior cervical ganglia significantly affected the expression of Snap25 in the gland. The pineal expression levels of Snap25 were not changed following intraperitoneal injection of isoproterenol. The strong expression of Snap25 in the pineal gland suggests the presence of secretory granules and microvesicles in the rat pinealocyte supporting the concept of a vesicular release. At the transcriptional level, this Snap25-based release mechanism does not exhibit any diurnal rhythmicity and is regulated independently of the sympathetic nervous input to the gland.
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Affiliation(s)
- Anna S Karlsen
- Department of Neuroscience and Pharmacology, Faculty of Health Sciences, Panum Institute, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark.
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Rath MF, Rohde K, Møller M. Circadian oscillations of molecular clock components in the cerebellar cortex of the rat. Chronobiol Int 2012; 29:1289-99. [PMID: 23131067 DOI: 10.3109/07420528.2012.728660] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The central circadian clock of the mammalian brain resides in the suprachiasmatic nucleus (SCN) of the hypothalamus. At the molecular level, the circadian clockwork of the SCN constitutes a self-sustained autoregulatory feedback mechanism reflected by the rhythmic expression of clock genes. However, recent studies have shown the presence of extrahypothalamic oscillators in other areas of the brain including the cerebellum. In the present study, the authors unravel the cerebellar molecular clock by analyzing clock gene expression in the cerebellum of the rat by use of radiochemical in situ hybridization and quantitative real-time polymerase chain reaction. The authors here show that all core clock genes, i.e., Per1, Per2, Per3, Cry1, Cry2, Clock, Arntl, and Nr1d1, as well as the clock-controlled gene Dbp, are expressed in the granular and Purkinje cell layers of the cerebellar cortex. Among these genes, Per1, Per2, Per3, Cry1, Arntl, Nr1d1, and Dbp were found to exhibit circadian rhythms in a sequential temporal manner similar to that of the SCN, but with several hours of delay. The results of lesion studies indicate that the molecular oscillatory profiles of Per1, Per2, and Cry1 in the cerebellum are controlled, though possibly indirectly, by the central clock of the SCN. These data support the presence of a circadian oscillator in the cortex of the rat cerebellum.
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Affiliation(s)
- Martin F Rath
- Department of Neuroscience and Pharmacology, Panum Institute, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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Bai RY, Staedtke V, Lidov HG, Eberhart CG, Riggins GJ. OTX2 represses myogenic and neuronal differentiation in medulloblastoma cells. Cancer Res 2012; 72:5988-6001. [PMID: 22986744 DOI: 10.1158/0008-5472.can-12-0614] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The brain development transcription factor OTX2 is overexpressed and/or genomically amplified in most medulloblastomas, but the mechanistic basis for its contributions in this setting are not understood. In this study, we identified OTX2 as a transcriptional repressor and a gatekeeper of myogenic and neuronal differentiation in medulloblastoma cells. OTX2 binds to the MyoD1 core enhancer through its homeobox domain, and the remarkable repressor activity exhibited by the homeobox domain renders OTX2 transcriptionally repressive. RNA interference-mediated attenuation of OTX2 expression triggered myogenic and neuronal differentiation in vitro and prolonged the survival in an orthotopic medulloblastoma mouse model. Conversely, inducing myogenic conversion of medulloblastoma cells led to the loss of OTX2 expression. In medullomyoblastoma, a medulloblastoma subtype containing muscle elements, myogenic cells share cytogenetic signatures with the primitive tumor cells and OTX2 expression was lost in the differentiated myogenic cells. Thus, OTX2 functions via its homeobox domain as a suppressor of differentiation, and the loss of OTX2 expression is linked to the myogenesis in medullomyoblastoma. Together, our findings illustrate the origin of muscle cells in medullomyoblastomas and the oncogenic mechanism of OTX2 as a repressor of diverse differentiating potential.
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Affiliation(s)
- Ren-Yuan Bai
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231, USA.
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Ochocinska MJ, Muñoz EM, Veleri S, Weller JL, Coon SL, Pozdeyev N, Iuvone PM, Goebbels S, Furukawa T, Klein DC. NeuroD1 is required for survival of photoreceptors but not pinealocytes: results from targeted gene deletion studies. J Neurochem 2012; 123:44-59. [PMID: 22784109 DOI: 10.1111/j.1471-4159.2012.07870.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
NeuroD1 encodes a basic helix-loop-helix transcription factor involved in the development of neural and endocrine structures, including the retina and pineal gland. To determine the effect of NeuroD1 knockout in these tissues, a Cre/loxP recombination strategy was used to target a NeuroD1 floxed gene and generate NeuroD1 conditional knockout (cKO) mice. Tissue specificity was conferred using Cre recombinase expressed under the control of the promoter of Crx, which is selectively expressed in the pineal gland and retina. At 2 months of age, NeuroD1 cKO retinas have a dramatic reduction in rod- and cone-driven electroretinograms and contain shortened and disorganized outer segments; by 4 months, NeuroD1 cKO retinas are devoid of photoreceptors. In contrast, the NeuroD1 cKO pineal gland appears histologically normal. Microarray analysis of 2-month-old NeuroD1 cKO retina and pineal gland identified a subset of genes that were affected 2-100-fold; in addition, a small group of genes exhibit altered differential night/day expression. Included in the down-regulated genes are Aipl1, which is necessary to prevent retinal degeneration, and Ankrd33, whose protein product is selectively expressed in the outer segments. These findings suggest that NeuroD1 may act through Aipl1 and other genes to maintain photoreceptor homeostasis.
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Affiliation(s)
- Margaret J Ochocinska
- Section on Neuroendocrinology, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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35
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Clokie SJH, Lau P, Kim HH, Coon SL, Klein DC. MicroRNAs in the pineal gland: miR-483 regulates melatonin synthesis by targeting arylalkylamine N-acetyltransferase. J Biol Chem 2012; 287:25312-24. [PMID: 22908386 PMCID: PMC3408182 DOI: 10.1074/jbc.m112.356733] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 05/14/2012] [Indexed: 11/06/2022] Open
Abstract
MicroRNAs (miRNAs) play a broad range of roles in biological regulation. In this study, rat pineal miRNAs were profiled for the first time, and their importance was evaluated by focusing on the main function of the pineal gland, melatonin synthesis. Massively parallel sequencing and related methods revealed the miRNA population is dominated by a small group of miRNAs as follows: ~75% is accounted for by 15 miRNAs; miR-182 represents 28%. In addition to miR-182, miR-183 and miR-96 are also highly enriched in the pineal gland, a distinctive pattern also found in the retina. This effort also identified previously unrecognized miRNAs and other small noncoding RNAs. Pineal miRNAs do not exhibit a marked night/day difference in abundance with few exceptions (e.g. 2-fold night/day differences in the abundance of miR-96 and miR-182); this contrasts sharply with the dynamic 24-h pattern that characterizes the pineal transcriptome. During development, the abundance of most pineal gland-enriched miRNAs increases; however, there is a marked decrease in at least one, miR-483. miR-483 is a likely regulator of melatonin synthesis, based on the following. It inhibits melatonin synthesis by pinealocytes in culture; it acts via predicted binding sites in the 3"-UTR of arylalkylamine N-acetyltransferase (Aanat) mRNA, the penultimate enzyme in melatonin synthesis, and it exhibits a developmental profile opposite to that of Aanat transcripts. Additionally, a miR-483 targeted antagonist increased melatonin synthesis in neonatal pinealocytes. These observations support the hypothesis that miR-483 suppresses Aanat mRNA levels during development and that the developmental decrease in miR-483 abundance promotes melatonin synthesis.
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Affiliation(s)
- Samuel J. H. Clokie
- From the Section on Neuroendocrinology, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892 and
| | - Pierre Lau
- the Center for Human Genetics and Leuven Institute for Neurodegenerative Disorders (LIND), University of Leuven, 3000 Leuven, Belgium
| | - Hyun Hee Kim
- From the Section on Neuroendocrinology, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892 and
| | - Steven L. Coon
- From the Section on Neuroendocrinology, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892 and
| | - David C. Klein
- From the Section on Neuroendocrinology, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892 and
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36
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Bedolla DE, Torre V. A component of retinal light adaptation mediated by the thyroid hormone cascade. PLoS One 2011; 6:e26334. [PMID: 22039463 PMCID: PMC3200322 DOI: 10.1371/journal.pone.0026334] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Accepted: 09/25/2011] [Indexed: 11/18/2022] Open
Abstract
Analysis with DNA-microrrays and real time PCR show that several genes involved in the thyroid hormone cascade, such as deiodinase 2 and 3 (Dio2 and Dio3) are differentially regulated by the circadian clock and by changes of the ambient light. The expression level of Dio2 in adult rats (2-3 months of age) kept continuously in darkness is modulated by the circadian clock and is up-regulated by 2 fold at midday. When the diurnal ambient light was on, the expression level of Dio2 increased by 4-8 fold and a consequent increase of the related protein was detected around the nuclei of retinal photoreceptors and of neurons in inner and outer nuclear layers. The expression level of Dio3 had a different temporal pattern and was down-regulated by diurnal light. Our results suggest that DIO2 and DIO3 have a role not only in the developing retina but also in the adult retina and are powerfully regulated by light. As the thyroid hormone is a ligand-inducible transcription factor controlling the expression of several target genes, the transcriptional activation of Dio2 could be a novel genomic component of light adaptation.
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Affiliation(s)
- Diana E. Bedolla
- Neurobiology Sector, International School for Advanced Studies (SISSA), Trieste, Italy
| | - Vincent Torre
- Neurobiology Sector, International School for Advanced Studies (SISSA), Trieste, Italy
- Italian Institute of Technology (IIT), SISSA-Unit, Trieste, Italy
- * E-mail:
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37
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Rovsing L, Clokie S, Bustos DM, Rohde K, Coon SL, Litman T, Rath MF, Møller M, Klein DC. Crx broadly modulates the pineal transcriptome. J Neurochem 2011; 119:262-74. [PMID: 21797868 DOI: 10.1111/j.1471-4159.2011.07405.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Cone-rod homeobox (Crx) encodes Crx, a transcription factor expressed selectively in retinal photoreceptors and pinealocytes, the major cell type of the pineal gland. In this study, the influence of Crx on the mammalian pineal gland was studied by light and electron microscopy and by use of microarray and qRTPCR technology, thereby extending previous studies on selected genes (Furukawa et al. 1999). Deletion of Crx was not found to alter pineal morphology, but was found to broadly modulate the mouse pineal transcriptome, characterized by a>2-fold down-regulation of 543 genes and a>2-fold up-regulation of 745 genes (p<0.05). Of these, one of the most highly up-regulated (18-fold) was Hoxc4, a member of the Hox gene family, members of which are known to control gene expression cascades. During a 24-h period, a set of 51 genes exhibited differential day/night expression in pineal glands of wild-type animals; only eight of these were also day/night expressed in the Crx⁻/⁻ pineal gland. However, in the Crx⁻/⁻ pineal gland 41 genes exhibited differential night/day expression that was not seen in wild-type animals. These findings indicate that Crx broadly modulates the pineal transcriptome and also influences differential night/day gene expression in this tissue. Some effects of Crx deletion on the pineal transcriptome might be mediated by Hoxc4 up-regulation.
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Affiliation(s)
- Louise Rovsing
- Department of Neuroscience and Pharmacology, Panum Institute, University of Copenhagen, Copenhagen, Denmark
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38
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Rohde K, Klein DC, Møller M, Rath MF. Rax : developmental and daily expression patterns in the rat pineal gland and retina. J Neurochem 2011; 118:999-1007. [PMID: 21749377 DOI: 10.1111/j.1471-4159.2011.07385.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Retina and anterior neural fold homeobox (Rax) gene encodes a transcription factor essential for vertebrate eye development. Recent microarray studies indicate that Rax is expressed in the adult rat pineal gland and retina. The present study reveals that Rax expression levels in the rat change significantly during retinal development with a peak occurring at embryonic day 18, whereas Rax expression in the pineal is relatively delayed and not detectable until embryonic day 20. In both tissues, Rax is expressed throughout postnatal development into adulthood. In the mature rat pineal gland, the abundance of Rax transcripts increases 2-fold during the light period with a peak occurring at dusk. These findings are consistent with the evidence that Rax is of functional importance in eye development and suggest a role of Rax in the developing pineal gland. In addition, it would appear possible that Rax contributes to phenotype maintenance in the mature retina and pineal gland and may facilitate 24-h changes in the pineal transcriptome.
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Affiliation(s)
- Kristian Rohde
- Department of Neuroscience and Pharmacology, Panum Institute, University of Copenhagen, Copenhagen, Denmark
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39
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Diaczok D, DiVall S, Matsuo I, Wondisford FE, Wolfe AM, Radovick S. Deletion of Otx2 in GnRH neurons results in a mouse model of hypogonadotropic hypogonadism. Mol Endocrinol 2011; 25:833-46. [PMID: 21436260 DOI: 10.1210/me.2010-0271] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
GnRH is the central regulator of reproductive function responding to central nervous system cues to control gonadotropin synthesis and secretion. GnRH neurons originate in the olfactory placode and migrate to the forebrain, in which they are found in a scattered distribution. Congenital idiopathic hypogonadotropic hypogonadism (CIHH) has been associated with mutations or deletions in a number of genes that participate in the development of GnRH neurons and expression of GnRH. Despite the critical role of GnRH in mammalian reproduction, a comprehensive understanding of the developmental factors that are responsible for regulating the establishment of mature GnRH neurons and the expression of GnRH is lacking. orthodenticle homeobox 2 (OTX2), a homeodomain protein required for the formation of the forebrain, has been shown to be expressed in GnRH neurons, up-regulated during GnRH neuronal development, and responsible for increased GnRH promoter activity in GnRH neuronal cell lines. Interestingly, mutations in Otx2 have been associated with human hypogonadotropic hypogonadism, but the mechanism by which Otx2 mutations cause CIHH is unknown. Here we show that deletion of Otx2 in GnRH neurons results in a significant decrease in GnRH neurons in the hypothalamus, a delay in pubertal onset, abnormal estrous cyclicity, and infertility. Taken together, these data provide in vivo evidence that Otx2 is critical for GnRH expression and reproductive competence.
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Affiliation(s)
- Daniel Diaczok
- Division of Pediatric Endocrinology, The Johns Hopkins University School of Medicine, 600 North Wolfe Street, Baltimore, Maryland 21287, USA
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Bustos DM, Bailey MJ, Sugden D, Carter DA, Rath MF, Møller M, Coon SL, Weller JL, Klein DC. Global daily dynamics of the pineal transcriptome. Cell Tissue Res 2011; 344:1-11. [PMID: 21302120 DOI: 10.1007/s00441-010-1094-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Accepted: 11/16/2010] [Indexed: 10/18/2022]
Abstract
Transcriptome profiling of the pineal gland has revealed night/day differences in the expression of a major fraction of the genes active in this tissue, with two-thirds of these being nocturnal increases. A set of over 600 transcripts exhibit two-fold to >100-fold daily differences in abundance. These changes appear to be primarily attributable to adrenergic-cyclic-AMP-dependent mechanisms, which are controlled via a neural pathway that includes the suprachiasmatic nucleus, the master circadian oscillator. In addition to melatonin synthesis, night/day differences in gene expression impact genes associated with several specialized functions, including the immune/inflammation response, photo-transduction, and thyroid hormone/retinoic acid biology. The following nonspecialized cellular features are also affected: adhesion, cell cycle/cell death, cytoskeleton, DNA modification, endothelium, growth, RNA modification, small molecule biology, transcription factors, vesicle biology, signaling involving Ca(2+), cyclic nucleotides, phospholipids, mitogen-activated protein kinases, the Wnt signaling pathway, and protein phosphorylation.
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Affiliation(s)
- Diego M Bustos
- Instituto Tecnológico de Chascomús (Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús), Camino Circunvalación Laguna km 6 cc164, B7130IWA, Chascomús, Argentina
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41
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Savastano LE, Castro AE, Fitt MR, Rath MF, Romeo HE, Muñoz EM. A standardized surgical technique for rat superior cervical ganglionectomy. J Neurosci Methods 2010; 192:22-33. [PMID: 20637235 DOI: 10.1016/j.jneumeth.2010.07.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Revised: 07/05/2010] [Accepted: 07/07/2010] [Indexed: 12/30/2022]
Abstract
Superior cervical ganglionectomy (SCGx) is a valuable microsurgical model to study the role of the sympathetic nervous system in a vast array of physiological and pathological processes, including homeostatic regulation, circadian biology and the dynamics of neuronal dysfunction and recovery after injury. Despite having several experimental applications in the rat, a thorough description of a standardized procedure has never been published. Here, we provide a brief review of the principal features and experimental uses of the SCGx, the surgical anatomy of the neck and sympathetic cervical chain, and a step-by-step description of how to consistently remove the superior cervical ganglia through the omohyoid muscle or the carotid triangle. Furthermore, we suggest procedures and precautions to be taken during and after surgery to optimize results and describe tools to validate surgical success. We expect that the following standardized and optimized protocol will allow researchers to organize knowledge into a cohesive framework in those areas where the SCGx is applied.
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Affiliation(s)
- Luis Emilio Savastano
- Institute of Histology and Embryology of Mendoza, School of Medicine, National University of Cuyo, Mendoza, Argentina.
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A 350 bp region of the proximal promoter of Rds drives cell-type specific gene expression. Exp Eye Res 2010; 91:186-94. [PMID: 20447394 DOI: 10.1016/j.exer.2010.04.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 04/23/2010] [Accepted: 04/26/2010] [Indexed: 11/23/2022]
Abstract
RDS (retinal degeneration slow) is a photoreceptor-specific tetraspanin protein required for the biogenesis and maintenance of rod and cone outer segments. Mutations in the Rds gene are associated with multiple forms of rod- and cone-dominant retinal degeneration. To gain more insight into the mechanisms underlying the regulation of this gene, the identification of regulatory sequences within the promoter of Rds was undertaken. A 3.5 kb fragment of the 5' flanking region of the mouse Rds gene was isolated and binding sites for Crx, Otx2, Nr2e3, RXR family members, Mef2C, Esrrb, NF1, AP1, and SP1 in addition to several E-boxes, GC-boxes and GAGA-boxes were identified. Crx binding sequences were conserved in all mammalian species examined. Truncation expression analysis of the Rds promoter region in Y-79 retinoblastoma cells showed maximal activity in the 350 bp proximal promoter region. We also show that inclusion of more distal fragments reduced promoter activity to the basal level, and that the promoter activities are cell-type and direction specific. Co-transfection with Nrl increased promoter activity, suggesting that this gene positively regulates Rds expression. Based on these findings, a relatively small fragment of the Rds promoter may be useful in future gene transfer studies to drive gene expression in photoreceptors.
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Larsen KB, Lutterodt MC, Møllgård K, Møller M. Expression of the homeobox genes OTX2 and OTX1 in the early developing human brain. J Histochem Cytochem 2010; 58:669-78. [PMID: 20354145 DOI: 10.1369/jhc.2010.955757] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
In rodents, the Otx2 gene is expressed in the diencephalon, mesencephalon, and cerebellum and is crucial for the development of these brain regions. Together with Otx1, Otx2 is known to cooperate with other genes to develop the caudal forebrain and, further, Otx1 is also involved in differentiation of young neurons of the deeper cortical layers. We have studied the spatial and temporal expression of the two homeobox genes OTX2 and OTX1 in human fetal brains from 7 to 14 weeks postconception by in situ hybridization and immunohistochemistry. OTX2 was expressed in the diencephalon, mesencephalon, and choroid plexus, with a minor expression in the basal telencephalon. The expression of OTX2 in the hippocampal anlage was strong, with no expression in the adjacent neocortex. Contrarily, the OTX1 expression was predominantly located in the proliferative zones of the neocortex. At later stages, the OTX2 protein was found in the subcommissural organ, pineal gland, and cerebellum. The early expression of OTX2 and OTX1 in proliferative cell layers of the human fetal brain supports the concept that these homeobox genes are important in neuronal cell development and differentiation: OTX1 primarily in the neocortex, and OTX2 in the archicortex, diencephalon, rostral brain stem, and cerebellum.
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Affiliation(s)
- Karen B Larsen
- Department of Neuroscience and Pharmacology, University of Copenhagen, Denmark.
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Møller M, Lund-Andersen C, Rovsing L, Sparre T, Bache N, Roepstorff P, Vorum H. Proteomics of the photoneuroendocrine circadian system of the brain. MASS SPECTROMETRY REVIEWS 2010; 29:313-325. [PMID: 19437489 DOI: 10.1002/mas.20237] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The photoneuroendocrine circadian system of the brain consists of (a) specialized photoreceptors in the retina, (b) a circadian generator located in the forebrain that contains "clock genes," (c) specialized nuclei in the forebrain involved in neuroendocrine secretion, and (d) the pineal gland. The circadian generator is a nucleus, called the suprachiasmatic nucleus (SCN). The neurons of this nucleus contain "clock genes," the transcription of which exhibits a circadian rhythm. Most circadian rhythms are generated by the neurons of this nucleus and, via neuronal and humoral connections, the SCN controls circadian activity of the brain and peripheral tissues. The endogenous oscillator of the SCN is each day entrained to the length of the daily photoperiod by light that reach the retina, and specialized photoreceptors transmit impulses to the SCN via the optic nerves. Mass screening for day/night variations in gene expression in the circadian system as well as in the whole brain and peripheral tissues have, during the last decade, been performed. However, studies of circadian changes in the proteome have been less investigated. In this survey, the anatomy and function of the circadian-generating system in mammals is described, and recent proteomic studies that investigate day/night changes in the retina, SCN, and pineal gland are reviewed. Further circadian changes controlled by the SCN in gene and protein expression in the liver are discussed.
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Affiliation(s)
- Morten Møller
- Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
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Kim JS, Coon SL, Weller JL, Blackshaw S, Rath MF, Møller M, Klein DC. Muscleblind-like 2: circadian expression in the mammalian pineal gland is controlled by an adrenergic-cAMP mechanism. J Neurochem 2009; 110:756-64. [PMID: 19457059 DOI: 10.1111/j.1471-4159.2009.06184.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Muscleblind-like 2 (Mbnl2) is a zinc finger protein first identified in Drosophila. It appears to be essential for photoreceptor development and to be involved in RNA splicing. Here we report that Mbnl2 is strongly expressed in the rat pineal gland. The abundance of pineal Mbnl2 transcripts follows a marked circadian rhythm with peak levels approximately sevenfold higher at night than day levels. Mbnl2 protein exhibits a similar rhythm. In vitro studies indicate that the abundance of Mbnl2 transcripts and protein are controlled by an adrenergic/cAMP mechanism.
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Affiliation(s)
- Jong-So Kim
- Program on Developmental Endocrinology and Genetics, Section on Neuroendocrinology, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
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Larsen KB, Lutterodt M, Rath MF, Møller M. Expression of the homeobox genes
PAX6
,
OTX2
, and
OTX1
in the early human fetal retina. Int J Dev Neurosci 2009; 27:485-92. [DOI: 10.1016/j.ijdevneu.2009.04.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Revised: 04/07/2009] [Accepted: 04/27/2009] [Indexed: 11/30/2022] Open
Affiliation(s)
- Karen B. Larsen
- Department of Neuroscience and Pharmacology, Faculty of Health SciencesUniversity of CopenhagenDenmark
| | - Melissa Lutterodt
- Laboratory of Biology and ReproductionRigshospitaletDenmark
- Department of Gynecology and ObstetricsFrederiksberg HospitalCopenhagenDenmark
| | - Martin F. Rath
- Department of Neuroscience and Pharmacology, Faculty of Health SciencesUniversity of CopenhagenDenmark
| | - Morten Møller
- Department of Neuroscience and Pharmacology, Faculty of Health SciencesUniversity of CopenhagenDenmark
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Bailey MJ, Coon SL, Carter DA, Humphries A, Kim JS, Shi Q, Gaildrat P, Morin F, Ganguly S, Hogenesch JB, Weller JL, Rath MF, Møller M, Baler R, Sugden D, Rangel ZG, Munson PJ, Klein DC. Night/day changes in pineal expression of >600 genes: central role of adrenergic/cAMP signaling. J Biol Chem 2009; 284:7606-22. [PMID: 19103603 PMCID: PMC2658055 DOI: 10.1074/jbc.m808394200] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 12/12/2008] [Indexed: 11/06/2022] Open
Abstract
The pineal gland plays an essential role in vertebrate chronobiology by converting time into a hormonal signal, melatonin, which is always elevated at night. Here we have analyzed the rodent pineal transcriptome using Affymetrix GeneChip(R) technology to obtain a more complete description of pineal cell biology. The effort revealed that 604 genes (1,268 probe sets) with Entrez Gene identifiers are differentially expressed greater than 2-fold between midnight and mid-day (false discovery rate <0.20). Expression is greater at night in approximately 70%. These findings were supported by the results of radiochemical in situ hybridization histology and quantitative real time-PCR studies. We also found that the regulatory mechanism controlling the night/day changes in the expression of most genes involves norepinephrine-cyclic AMP signaling. Comparison of the pineal gene expression profile with that in other tissues identified 334 genes (496 probe sets) that are expressed greater than 8-fold higher in the pineal gland relative to other tissues. Of these genes, 17% are expressed at similar levels in the retina, consistent with a common evolutionary origin of these tissues. Functional categorization of the highly expressed and/or night/day differentially expressed genes identified clusters that are markers of specialized functions, including the immune/inflammation response, melatonin synthesis, photodetection, thyroid hormone signaling, and diverse aspects of cellular signaling and cell biology. These studies produce a paradigm shift in our understanding of the 24-h dynamics of the pineal gland from one focused on melatonin synthesis to one including many cellular processes.
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Affiliation(s)
- Michael J Bailey
- Section on Neuroendocrinology, Program on Developmental Endocrinology and Genetics, NICHD, National Institutes of Health, Bethesda, Maryland 20892, USA
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48
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Rath MF, Bailey MJ, Kim JS, Ho AK, Gaildrat P, Coon SL, Møller M, Klein DC. Developmental and diurnal dynamics of Pax4 expression in the mammalian pineal gland: nocturnal down-regulation is mediated by adrenergic-cyclic adenosine 3',5'-monophosphate signaling. Endocrinology 2009; 150:803-11. [PMID: 18818287 PMCID: PMC2646524 DOI: 10.1210/en.2008-0882] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Pax4 is a homeobox gene that is known to be involved in embryonic development of the endocrine pancreas. In this tissue, Pax4 counters the effects of the related protein, Pax6. Pax6 is essential for development of the pineal gland. In this study we report that Pax4 is strongly expressed in the pineal gland and retina of the rat. Pineal Pax4 transcripts are low in the fetus and increase postnatally; Pax6 exhibits an inverse pattern of expression, being more strongly expressed in the fetus. In the adult the abundance of Pax4 mRNA exhibits a diurnal rhythm in the pineal gland with maximal levels occurring late during the light period. Sympathetic denervation of the pineal gland by superior cervical ganglionectomy prevents the nocturnal decrease in pineal Pax4 mRNA. At night the pineal gland is adrenergically stimulated by release of norepinephrine from the sympathetic innervation; here, we found that treatment with adrenergic agonists suppresses pineal Pax4 expression in vivo and in vitro. This suppression appears to be mediated by cAMP, a second messenger of norepinephrine in the pineal gland, based on the observation that treatment with a cAMP mimic reduces pineal Pax4 mRNA levels. These findings suggest that the nocturnal decrease in pineal Pax4 mRNA is controlled by the sympathetic neural pathway that controls pineal function acting via an adrenergic-cAMP mechanism. The daily changes in Pax4 expression may influence gene expression in the pineal gland.
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Affiliation(s)
- Martin F Rath
- Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
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49
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Rath MF, Bailey MJ, Kim JS, Coon SL, Klein DC, Møller M. Developmental and daily expression of the Pax4 and Pax6 homeobox genes in the rat retina: localization of Pax4 in photoreceptor cells. J Neurochem 2008; 108:285-94. [PMID: 19012751 DOI: 10.1111/j.1471-4159.2008.05765.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pax4 is a homeobox gene encoding Pax4, a transcription factor that is essential for embryonic development of the endocrine pancreas. In the pancreas, Pax4 counters the effects of the related transcription factor, Pax6, which is known to be essential for eye morphogenesis. In this study, we have discovered that Pax4 is strongly expressed in retinal photoreceptors of the rat. Pax4 expression is not detectable in the foetal eye; however, postnatal Pax4 transcript levels rapidly increase. In contrast, Pax6 exhibits an inverse developmental pattern of expression being more strongly expressed in the foetal eye. Histological analysis revealed that Pax4 mRNA is exclusively expressed in the retinal photoreceptors, whereas Pax6 mRNA and protein are present in the inner nuclear layer and in the ganglion cell layer of the mature retina. In the adult retina, Pax4 transcripts exhibit a diurnal rhythm with maximal levels occurring during the light period, whereas retinal Pax6 transcript levels do not change throughout the day. The daily changes in Pax4 expression may contribute to daily changes in function in the differentiated retinal photoreceptor.
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Affiliation(s)
- Martin F Rath
- Department of Neuroscience and Pharmacology, Panum Institute, University of Copenhagen, Copenhagen, Denmark.
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50
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Diaczok D, Romero C, Zunich J, Marshall I, Radovick S. A novel dominant negative mutation of OTX2 associated with combined pituitary hormone deficiency. J Clin Endocrinol Metab 2008; 93:4351-9. [PMID: 18728160 PMCID: PMC2582563 DOI: 10.1210/jc.2008-1189] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
CONTEXT Combined pituitary hormone deficiency (CPHD) is characterized by deficiencies in more than one anterior pituitary hormone. Mutations in developmental factors responsible for pituitary cell specification and gene expression have been found in CPHD patients. OTX2, a bicoid class homeodomain protein, is necessary for both forebrain development and transactivation of the HESX1 promoter, but as of yet, has not been associated with CPHD. OBJECTIVE The goal of this study was to identify and characterize novel mutations in pituitary specific transcription factors from CPHD patients. DESIGN Genomic DNA was isolated from patients with hypopituitarism to amplify and sequence eight pituitary specific transcription factors (HESX1, LHX3, LHX4, OTX2, PITX2, POU1F1, PROP1, and SIX6). Characterization of novel mutations is based on structural and functional studies. RESULTS We describe two unrelated children with CPHD who presented with neonatal hypoglycemia, and deficiencies of GH, TSH, LH, FSH, and ACTH. Magnetic resonance imaging revealed anterior pituitary hypoplasia with an ectopic posterior pituitary. A novel heterozygous OTX2 mutation (N233S) was identified. Wild-type and mutant OTX2 proteins bind equivalently to bicoid binding sites, whereas mutant OTX2 revealed decreased transactivation. CONCLUSIONS A novel mutation in OTX2 binds normally to target genes and acts as a dominant negative inhibitor of HESX1 gene expression. This suggests that the expression of HESX1, required for spaciotemporal development of anterior pituitary cell types, when disrupted, results in an absent or underdeveloped anterior pituitary with diminished hormonal expression. These results demonstrate a novel mechanism for CPHD and extend our knowledge of the spectrum of gene mutations causing CPHD.
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Affiliation(s)
- Daniel Diaczok
- Division of Pediatric Endocrinology, The Johns Hopkins University School of Medicine, 600 North Wolfe Street, CMSC 406, Baltimore, Maryland 21287, USA
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