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Zhang W, Dao JJ, Li Q, Liu C, Qiao CM, Cui C, Shen YQ, Zhao WJ. Neuregulin 1 mitigated prolactin deficiency through enhancing TRPM8 signaling under the influence of melatonin in senescent pituitary lactotrophs. Int J Biol Macromol 2024; 275:133659. [PMID: 38969045 DOI: 10.1016/j.ijbiomac.2024.133659] [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] [Received: 03/22/2024] [Revised: 07/02/2024] [Accepted: 07/02/2024] [Indexed: 07/07/2024]
Abstract
The age-related alterations in pituitary function, including changes in prolactin (PRL) production contributes to the systemic susceptibility to age-related diseases. Our previous research has shown the involvement of Nrg1 in regulating the expression and secretion of PRL. However, the precise role of Nrg1 in mitigating the senescence of pituitary lactotrophs and the underlying mechanisms are yet to be comprehended. Here, data from the GEPIA database was used to evaluate the association between transient receptor potential cation channel subfamily M member 8 (TRPM8) and PRL in normal human pituitary tissues, followed by immunofluorescence verification using a human pituitary tissue microarray. TRPM8 levels showed a significant positive association with PRL expression in normal human pituitary tissues, and both TRPM8 and PRL levels declined during aging, suggesting that TRPM8 may regulate pituitary aging by affecting PRL production. It was also found that treatment with exogenous neuregulin 1 (Nrg1) markedly delayed the senescence of GH3 cells (rat lactotroph cell line) generated by D-galactose (D-gal). In addition, melatonin reduced the levels of senescence-related markers in senescent pituitary cells by promoting Nrg1 / ErbB4 signaling, stimulating PRL expression and secretion. Further investigation showed that Nrg1 attenuated senescence in pituitary cells by increasing TRPM8 expression. Downregulation of TRPM8 activation eliminated Nrg1-mediated amelioration of pituitary cell senescence. These findings demonstrate the critical function of Nrg1 / ErbB signaling in delaying pituitary lactotroph cell senescence and enhancing PRL production via promoting TRPM8 expression under the modulation of melatonin.
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Affiliation(s)
- Wei Zhang
- Cell Biology Department, Wuxi School of Medicine, Jiangnan University, 214122 Wuxi, Jiangsu, China; Department of Pathogen Biology, Guizhou Nursing Vocational College, Guiyang 550000, Guizhou, China
| | - Ji-Ji Dao
- Cell Biology Department, Wuxi School of Medicine, Jiangnan University, 214122 Wuxi, Jiangsu, China
| | - Qian Li
- Cell Biology Department, Wuxi School of Medicine, Jiangnan University, 214122 Wuxi, Jiangsu, China
| | - Chong Liu
- Cell Biology Department, Wuxi School of Medicine, Jiangnan University, 214122 Wuxi, Jiangsu, China
| | - Chen-Meng Qiao
- Department of Neurodegeneration and Neuroinjury, Wuxi School of Medicine, Jiangnan University, 214122 Wuxi, Jiangsu, China
| | - Chun Cui
- Department of Neurodegeneration and Neuroinjury, Wuxi School of Medicine, Jiangnan University, 214122 Wuxi, Jiangsu, China
| | - Yan-Qin Shen
- Department of Neurodegeneration and Neuroinjury, Wuxi School of Medicine, Jiangnan University, 214122 Wuxi, Jiangsu, China
| | - Wei-Jiang Zhao
- Cell Biology Department, Wuxi School of Medicine, Jiangnan University, 214122 Wuxi, Jiangsu, China.
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2
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Malintha GHT, Woo DW, Celino-Brady FT, Seale AP. Temperature modulates the osmosensitivity of tilapia prolactin cells. Sci Rep 2023; 13:20217. [PMID: 37980366 PMCID: PMC10657356 DOI: 10.1038/s41598-023-47044-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Accepted: 11/08/2023] [Indexed: 11/20/2023] Open
Abstract
In euryhaline fish, prolactin (Prl) plays an essential role in freshwater (FW) acclimation. In the euryhaline and eurythermal Mozambique tilapia, Oreochromis mossambicus, Prl cells are model osmoreceptors, recently described to be thermosensitive. To investigate the effects of temperature on osmoreception, we incubated Prl cells of tilapia acclimated to either FW or seawater (SW) in different combinations of temperatures (20, 26 and 32 °C) and osmolalities (280, 330 and 420 mOsm/kg) for 6 h. Release of both Prl isoforms, Prl188 and Prl177, increased in hyposmotic media and were further augmented with a rise in temperature. Hyposmotically-induced release of Prl188, but not Prl177, was suppressed at 20 °C. In SW fish, mRNA expression of prl188 increased with rising temperatures at lower osmolalities, while and prl177 decreased at 32 °C and higher osmolalities. In Prl cells of SW-acclimated tilapia incubated in hyperosmotic media, the expressions of Prl receptors, prlr1 and prlr2, and the stretch-activated Ca2+ channel, trpv4,decreased at 32 °C, suggesting the presence of a cellular mechanism to compensate for elevated Prl release. Transcription factors, pou1f1, pou2f1b, creb3l1, cebpb, stat3, stat1a and nfat1c, known to regulate prl188 and prl177, were also downregulated at 32 °C. Our findings provide evidence that osmoreception is modulated by temperature, and that both thermal and osmotic responses vary with acclimation salinity.
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Affiliation(s)
- G H T Malintha
- Department of Human Nutrition, Food and Animal Sciences, University of Hawai'i at Mānoa, 1955 East-West Road, Honolulu, HI, 96822, USA
| | - Daniel W Woo
- Department of Human Nutrition, Food and Animal Sciences, University of Hawai'i at Mānoa, 1955 East-West Road, Honolulu, HI, 96822, USA
| | - Fritzie T Celino-Brady
- Department of Human Nutrition, Food and Animal Sciences, University of Hawai'i at Mānoa, 1955 East-West Road, Honolulu, HI, 96822, USA
- Division of Genetics, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, 97006, USA
| | - Andre P Seale
- Department of Human Nutrition, Food and Animal Sciences, University of Hawai'i at Mānoa, 1955 East-West Road, Honolulu, HI, 96822, USA.
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3
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Hewage TMG, Woo DW, Celino-Brady FT, Seale AP. Temperature modulates the osmosensitivity of tilapia prolactin cells. RESEARCH SQUARE 2023:rs.3.rs-2524830. [PMID: 36909603 PMCID: PMC10002831 DOI: 10.21203/rs.3.rs-2524830/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
In euryhaline fish, prolactin (Prl) plays an essential role in freshwater (FW) acclimation. In the euryhaline and eurythermal Mozambique tilapia, Oreochromis mossambicus, Prl cells are model osmoreceptors, recently described to be thermosensitive. To investigate the effects of temperature on osmoreception, we incubated Prl cells of tilapia acclimated to either FW or seawater (SW) in different temperature (20, 26 and 32°C) and osmolality (280, 330 and 420 mOsm/kg) combinations for 6 h. Release of both Prl isoforms, Prl188 and Prl177, increased in hyposmotic media and were further augmented with a rise in temperature. Hyposmotically-induced release of Prl188 was inhibited at 20°C. In SW fish, mRNA expression of prl188 and prl177 showed direct and inverse relationships with temperature, respectively. In SW-acclimated tilapia Prl cells incubated in hyperosmotic media, Prl receptors, prlr1 and prlr2, and the stretch-activated Ca2+ channel, trpv4, were inhibited at 32°C, suggesting the presence of a cellular mechanism to compensate for elevated Prl release. Transcription factors, pou1f1, pou2f1b, creb3l1, cebpb, stat3, stat1a and nfat1c, known to regulate prl188 and prl177, were also downregulated at 32°C. Our findings provide evidence that osmoreception is modulated by temperature, and that both thermal and osmotic responses vary with acclimation salinity.
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4
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Mhalhel K, Montalbano G, Giurdanella G, Abbate F, Laurà R, Guerrera MC, Germanà A, Levanti M. Histological and immunohistochemical study of gilthead seabream tongue from the early stage of development: TRPV4 potential roles. Ann Anat 2022; 244:151985. [PMID: 35914630 DOI: 10.1016/j.aanat.2022.151985] [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: 02/14/2022] [Revised: 05/31/2022] [Accepted: 07/14/2022] [Indexed: 10/16/2022]
Abstract
BACKGROUND Taste buds, the morphofunctional units for taste perception, transduce gustatory stimuli using G protein-coupled receptors, and a complex arrangement of ion channels, among which TRPV4, a member of the TRP superfamily. Studies on taste buds development on gilthead seabream are unknown, and the TRPV4 expression on fish taste cells studies were conducted only on zebrafish. METHODS In our study, we have investigated the histological features of the gilthead seabream tongue dorsal surface from the earliest stage of development using Masson trichrome with aniline blue staining. Additionally, TRPV4 expression pattern was studied by means of immunohistochemical labeling and quantitative RT-PCR. RESULTS We have recorded for the first time on gilthead seabream lingual dorsal surface the presence of, stage specific, three types of taste buds: type I, type II and type III in larvae, juvenile and adults respectively. At 40 days post hatching, taste buds were mature-looking. TRPV4 expression was detected in a subpopulation of taste cells of larvae, juveniles, and adults. Furthermore, TRPV4 was expressed in the basal epithelial cells of the tongue at the larvae and juvenile stage, while this expression pattern was more diffused within all the epithelial cell layers on the adult. CONCLUSION Our findings presume a taste sensory role of TRPV4 in the three stage-specific taste buds and oral epithelia of gilthead seabream. In addition to its sensory role on the epithelial cell layers, we hypothesize that TRPV4 is implicated in epithelial cells differentiation and membrane protection.
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Affiliation(s)
- Kamel Mhalhel
- Zebrafish Neuromorphology Lab, Department of Veterinary Sciences, Via Palatucci snc, University of Messina, 98168 Messina, Italy.
| | - Giuseppe Montalbano
- Zebrafish Neuromorphology Lab, Department of Veterinary Sciences, Via Palatucci snc, University of Messina, 98168 Messina, Italy
| | - Giovanni Giurdanella
- Faculty of Medicine and surgery, ''Kore'' University of Enna, Contrada Santa Panasia, 94100 Enna, Italy
| | - Francesco Abbate
- Zebrafish Neuromorphology Lab, Department of Veterinary Sciences, Via Palatucci snc, University of Messina, 98168 Messina, Italy
| | - Rosaria Laurà
- Zebrafish Neuromorphology Lab, Department of Veterinary Sciences, Via Palatucci snc, University of Messina, 98168 Messina, Italy
| | - Maria Cristina Guerrera
- Zebrafish Neuromorphology Lab, Department of Veterinary Sciences, Via Palatucci snc, University of Messina, 98168 Messina, Italy
| | - Antonino Germanà
- Zebrafish Neuromorphology Lab, Department of Veterinary Sciences, Via Palatucci snc, University of Messina, 98168 Messina, Italy
| | - Maria Levanti
- Zebrafish Neuromorphology Lab, Department of Veterinary Sciences, Via Palatucci snc, University of Messina, 98168 Messina, Italy.
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5
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Cloning and functional characterization of medaka TRPV4. Comp Biochem Physiol A Mol Integr Physiol 2022; 267:111182. [PMID: 35247590 DOI: 10.1016/j.cbpa.2022.111182] [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: 10/20/2021] [Revised: 02/25/2022] [Accepted: 02/26/2022] [Indexed: 11/20/2022]
Abstract
Medaka, Oryzias latipes is distributed in fresh water of South Asia. To study roles of TRPV4 in osmosensing and adaption mechanism of medaka during changes in salinity environment, we isolated the cDNA for TRPV4 from medaka (olTRPV4) and characterized it. The electrophysiological analysis using Xenopus oocytes revealed that olTRPV4 can be activated by a TRPV4-specific agonist, GSK1016790A and acid at pH 5. Further, olTRPV4 was sensitive to 2-APB. Although warm temperatures activate mammalian TRPV4, olTRPV4 was activated by cold and hot stimulation. The threshold for cold activation was determined as 13.13 ± 0.60 °C, and the heat-activation threshold was 40.26 ± 0.25 °C. Further, when olTRPV4-expressing oocytes were stimulated by hypotonic solution, an apparent activation was observed. We further found that the expression of this hypotonic sensor, olTRPV4 was significantly down-regulated in gills but up-regulated in brains of sea water-acclimated medaka. Results demonstrated that olTRPV4 must function as an osmosensor and play important roles in adaption mechanism of medaka fish in various salinity environments.
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Woo DW, Malintha GHT, Celino-Brady FT, Yamaguchi Y, Breves JP, Seale AP. Tilapia prolactin cells are thermosensitive osmoreceptors. Am J Physiol Regul Integr Comp Physiol 2022; 322:R609-R619. [PMID: 35438003 DOI: 10.1152/ajpregu.00027.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Prolactin (PRL) cells within the rostral pars distalis (RPD) of euryhaline and eurythermal Mozambique tilapia, Oreochromis mossambicus, rapidly respond to a hyposmotic stimulus by releasing two distinct PRL isoforms, PRL188 and PRL177. Here, we describe how environmentally relevant temperature changes affected mRNA levels of PRL188 and PRL177 and the release of immunoreactive prolactins from RPDs and dispersed PRL cells. When applied under isosmotic conditions (330 mOsm/kg), a 6 °C rise in temperature stimulated the release of PRL188 and PRL177 from both RPDs and dispersed PRL cells under perifusion. When exposed to this same change in temperature, ~50% of dispersed PRL cells gradually increased in volume by ~8%, a response partially inhibited by the water channel blocker, mercuric chloride. Following their response to increased temperature, PRL cells remained responsive to a hyposmotic stimulus (280 mOsm/kg). The mRNA expression of transient potential vanilloid 4, a Ca2+-channel involved in hyposomotically-induced PRL release, was elevated in response to a rise in temperature in dispersed PRL cells and RPDs at 6 and 24 h, respectively; prl188 and prl177 mRNAs were unaffected. Our findings indicate that thermosensitive PRL release is mediated, at least partially, through a cell-volume dependent pathway similar to how osmoreceptive PRL release is achieved.
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Affiliation(s)
- Daniel W Woo
- Department of Human Nutrition, Food and Animal Sciences, University of Hawaii at Manoa, Honolulu, HI, United States
| | - G H T Malintha
- Department of Human Nutrition, Food and Animal Sciences, University of Hawaii at Manoa, Honolulu, HI, United States
| | - Fritzie T Celino-Brady
- Department of Human Nutrition, Food and Animal Sciences, University of Hawaii at Manoa, Honolulu, HI, United States
| | - Yoko Yamaguchi
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, Matsue, Japan
| | - Jason P Breves
- Department of Biology, Skidmore College, Saratoga Springs, NY, United States
| | - Andre P Seale
- Department of Human Nutrition, Food and Animal Sciences, University of Hawaii at Manoa, Honolulu, HI, United States
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Nisembaum LG, Loentgen G, L’Honoré T, Martin P, Paulin CH, Fuentès M, Escoubeyrou K, Delgado MJ, Besseau L, Falcón J. Transient Receptor Potential-Vanilloid (TRPV1-TRPV4) Channels in the Atlantic Salmon, Salmo salar. A Focus on the Pineal Gland and Melatonin Production. Front Physiol 2022; 12:784416. [PMID: 35069244 PMCID: PMC8782258 DOI: 10.3389/fphys.2021.784416] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 12/07/2021] [Indexed: 11/13/2022] Open
Abstract
Fish are ectotherm, which rely on the external temperature to regulate their internal body temperature, although some may perform partial endothermy. Together with photoperiod, temperature oscillations, contribute to synchronizing the daily and seasonal variations of fish metabolism, physiology and behavior. Recent studies are shedding light on the mechanisms of temperature sensing and behavioral thermoregulation in fish. In particular, the role of some members of the transient receptor potential channels (TRP) is being gradually unraveled. The present study in the migratory Atlantic salmon, Salmo salar, aims at identifying the tissue distribution and abundance in mRNA corresponding to the TRP of the vanilloid subfamilies, TRPV1 and TRPV4, and at characterizing their putative role in the control of the temperature-dependent modulation of melatonin production-the time-keeping hormone-by the pineal gland. In Salmo salar, TRPV1 and TRPV4 mRNA tissue distribution appeared ubiquitous; mRNA abundance varied as a function of the month investigated. In situ hybridization and immunohistochemistry indicated specific labeling located in the photoreceptor cells of the pineal gland and the retina. Additionally, TRPV analogs modulated the production of melatonin by isolated pineal glands in culture. The TRPV1 agonist induced an inhibitory response at high concentrations, while evoking a bell-shaped response (stimulatory at low, and inhibitory at high, concentrations) when added with an antagonist. The TRPV4 agonist was stimulatory at the highest concentration used. Altogether, the present results agree with the known widespread distribution and role of TRPV1 and TRPV4 channels, and with published data on trout (Oncorhynchus mykiss), leading to suggest these channels mediate the effects of temperature on S. salar pineal melatonin production. We discuss their involvement in controlling the timing of daily and seasonal events in this migratory species, in the context of an increasing warming of water temperatures.
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Affiliation(s)
- Laura Gabriela Nisembaum
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
| | - Guillaume Loentgen
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
| | - Thibaut L’Honoré
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
| | - Patrick Martin
- Conservatoire National du Saumon Sauvage, Chanteuges, France
| | - Charles-Hubert Paulin
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
| | - Michael Fuentès
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
| | - Karine Escoubeyrou
- SU, CNRS Fédération 3724, Observatoire Océanologique, Banyuls-sur-Mer, France
| | - María Jesús Delgado
- Departamento de Genética, Fisiología y Microbiologia, Facultad de Biología, Universidad Complutense de Madrid, Madrid, Spain
| | - Laurence Besseau
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
| | - Jack Falcón
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
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Lee HJ, Lee SY, Kim YK. Molecular characterization of transient receptor potential vanilloid 4 (TRPV4) gene transcript variant mRNA of chum salmon Oncorhynchus keta in response to salinity or temperature changes. Gene 2021; 795:145779. [PMID: 34144144 DOI: 10.1016/j.gene.2021.145779] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 06/11/2021] [Accepted: 06/14/2021] [Indexed: 01/03/2023]
Abstract
Transient receptor potential vanilloid 4 (TRPV4) is an osmosensory cation channel that respond to an increase in cell volume and participates in various physiological functions. Among organisms in aquatic environments, euryhaline teleost is are suitable experimental models to study ion channel proteins related to physiological functions involving osmosensing. Among the studies of various regulatory molecules that mediate osmotic regulation in fish, however, information is lacking, particularly on the TRP family. This study investigated the structural characteristics of theTRPV4 gene of chum salmon (Oncorhynchus keta) and their responses to changes in salinity and temperature. Interestingly, TRPV4 generates transcript variants of the intron-retention form through alternative splicing, resulting in a frameshift leading to the generation of transcripts of different structures. In particular, TRPV4 x1 and TRPV x2 mRNAs were predominant in the gill and skin including at the lateral line. The expression levels of chum salmon TRPV4 x1 were significantly increased with increase in salinity and temperature, whereas TRPV4 x2 mainly responded to temperature decrease. Overall, these results demonstrate for the first time the effects of salinity and temperature on the expression of two salmonid TRPV4 transcript variants, suggesting their contribution to the regulation of hydromineral balance.
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Affiliation(s)
- Hwa Jin Lee
- Department of Marine Biotechnology, Gangneung-Wonju National University, Gangneung 25457, South Korea
| | - Sang Yoon Lee
- The East Coast Research Institute of Life Science, Gangneung-Wonju National University, Gangneung 25457, South Korea
| | - Yi Kyung Kim
- Department of Marine Biotechnology, Gangneung-Wonju National University, Gangneung 25457, South Korea; The East Coast Research Institute of Life Science, Gangneung-Wonju National University, Gangneung 25457, South Korea.
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9
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Seale AP, Malintha GHT, Celino-Brady FT, Head T, Belcaid M, Yamaguchi Y, Lerner DT, Baltzegar DA, Borski RJ, Stoytcheva ZR, Breves JP. Transcriptional regulation of prolactin in a euryhaline teleost: Characterisation of gene promoters through in silico and transcriptome analyses. J Neuroendocrinol 2020; 32:e12905. [PMID: 32996203 PMCID: PMC8612711 DOI: 10.1111/jne.12905] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 07/31/2020] [Accepted: 08/26/2020] [Indexed: 12/20/2022]
Abstract
The sensitivity of prolactin (Prl) cells of the Mozambique tilapia (Oreochromis mossambicus) pituitary to variations in extracellular osmolality enables investigations into how osmoreception underlies patterns of hormone secretion. Through the actions of their main secretory products, Prl cells play a key role in supporting hydromineral balance of fishes by controlling the major osmoregulatory organs (ie, gill, intestine and kidney). The release of Prl from isolated cells of the rostral pars distalis (RPD) occurs in direct response to physiologically relevant reductions in extracellular osmolality. Although the particular signal transduction pathways that link osmotic conditions to Prl secretion have been identified, the processes that underlie hyposmotic induction of prl gene expression remain unknown. In this short review, we describe two distinct tilapia gene loci that encode Prl177 and Prl188 . From our in silico analyses of prl177 and prl188 promoter regions (approximately 1000 bp) and a transcriptome analysis of RPDs from fresh water (FW)- and seawater (SW)-acclimated tilapia, we propose a working model for how multiple transcription factors link osmoreceptive processes with adaptive patterns of prl177 and prl188 gene expression. We confirmed via RNA-sequencing and a quantitative polymerase chain reaction that multiple transcription factors emerging as predicted regulators of prl gene expression are expressed in the RPD of tilapia. In particular, gene transcripts encoding pou1f1, stat3, creb3l1, pbxip1a and stat1a were highly expressed; creb3l1, pbxip1a and stat1a were elevated in fish acclimated to SW vs FW. Combined, our in silico and transcriptome analyses set a path for resolving how adaptive patterns of Prl secretion are achieved via the integration of osmoreceptive processes with the control of prl gene transcription.
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Affiliation(s)
- Andre P. Seale
- Department of Human Nutrition, Food and Animal Sciences, University of Hawai’i at Mānoa, Honolulu, HI, USA
| | | | - Fritzie T. Celino-Brady
- Department of Human Nutrition, Food and Animal Sciences, University of Hawai’i at Mānoa, Honolulu, HI, USA
| | - Tony Head
- Department of Human Nutrition, Food and Animal Sciences, University of Hawai’i at Mānoa, Honolulu, HI, USA
| | - Mahdi Belcaid
- Hawai’i Institute of Marine Biology, University of Hawai’i at Mānoa, Kaneohe, HI, USA
| | - Yoko Yamaguchi
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, Matsue, Japan
| | - Darren T. Lerner
- University of Hawai’i Sea Grant College Program, University of Hawai’i at Mānoa, Honolulu, HI, USA
| | - David A. Baltzegar
- Genomic Sciences Laboratory, Office of Research and Innovation, North Carolina State University, Raleigh, NC, USA
| | - Russell J. Borski
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA
| | - Zoia R. Stoytcheva
- Department of Human Nutrition, Food and Animal Sciences, University of Hawai’i at Mānoa, Honolulu, HI, USA
| | - Jason P. Breves
- Department of Biology, Skidmore College, Saratoga Springs, NY, USA
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10
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Sun Z, Lou F, Zhang Y, Song N. Gill Transcriptome Sequencing and De Novo Annotation of Acanthogobius ommaturus in Response to Salinity Stress. Genes (Basel) 2020; 11:genes11060631. [PMID: 32521805 PMCID: PMC7349121 DOI: 10.3390/genes11060631] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 05/23/2020] [Accepted: 06/04/2020] [Indexed: 01/17/2023] Open
Abstract
Acanthogobius ommaturus is a euryhaline fish widely distributed in coastal, bay and estuarine areas, showing a strong tolerance to salinity. In order to understand the mechanism of adaptation to salinity stress, RNA-seq was used to compare the transcriptome responses of Acanthogobius ommaturus to the changes of salinity. Four salinity gradients, 0 psu, 15 psu (control), 30 psu and 45 psu were set to conduct the experiment. In total, 131,225 unigenes were obtained from the gill tissue of A. ommaturus using the Illumina HiSeq 2000 platform (San Diego, USA). Compared with the gene expression profile of the control group, 572 differentially expressed genes (DEGs) were screened, with 150 at 0 psu, 170 at 30 psu, and 252 at 45 psu. Additionally, among these DEGs, Gene Ontology (GO) analysis indicated that binding, metabolic processes and cellular processes were significantly enriched. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways analysis detected 3, 5 and 8 pathways related to signal transduction, metabolism, digestive and endocrine systems at 0 psu, 30 psu and 45 psu, respectively. Based on GO enrichment analysis and manual literature searches, the results of the present study indicated that A. ommaturus mainly responded to energy metabolism, ion transport and signal transduction to resist the damage caused by salinity stress. Eight DEGs were randomly selected for further validation by quantitative real-time PCR (qRT-PCR) and the results were consistent with the RNA-seq data.
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Affiliation(s)
| | | | | | - Na Song
- Correspondence: or ; Tel.: +86-532-820-31658
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11
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Liu ST, Chou MY, Wu LC, Horng JL, Lin LY. Transient receptor potential vanilloid 4 modulates ion balance through the isotocin pathway in zebrafish (Danio rerio). Am J Physiol Regul Integr Comp Physiol 2020; 318:R751-R759. [DOI: 10.1152/ajpregu.00307.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Isotocin controls ion regulation through modulating the functions of ionocytes (also called mitochondria-rich cells or chloride cells). However, little is known about the upstream molecule of the isotocin system. Herein, we identify transient receptor potential vanilloid 4 (TRPV4), which regulates the mRNA and protein expressions of isotocin and affects ion regulation through the isotocin pathway. Double immunohistochemical results showed that TRPV4 is expressed in isotocinergic neurons in the hypothalamus of the adult zebrafish brain. To further elucidate the roles of TRPV4, we manipulated TRPV4 protein expression and evaluated its ionoregulatory functions in zebrafish embryos. TRPV4 gene knockdown with morpholino oligonucleotides decreased ionic contents (Na+, Cl−, and Ca2+) of whole larvae and the H+-secreting function of larval skin of zebrafish. mRNA expressions of ionocyte-related transporters, including H+-ATPase, the epithelial Ca2+ channel, and the Na+-Cl− cotransporter, were also suppressed in trpv4 morphants. Numbers of ionocytes (H+-ATPase-rich cells and Na+-K+-ATPase-rich cells) and epidermal stem cells in zebrafish larval skin also decreased after trpv4 knockdown. Our results showed that TRPV4 modulates ion balance through the isotocin pathway.
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Affiliation(s)
- Sian-Tai Liu
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Ming-Yi Chou
- Department of Life Science, National Taiwan University, Taipei, Taiwan
| | - Liang-Chun Wu
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Jiun-Lin Horng
- Department of Anatomy and Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Li-Yih Lin
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
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12
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Chang JP, Pemberton JG. Comparative aspects of GnRH-Stimulated signal transduction in the vertebrate pituitary - Contributions from teleost model systems. Mol Cell Endocrinol 2018; 463:142-167. [PMID: 28587765 DOI: 10.1016/j.mce.2017.06.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 05/31/2017] [Accepted: 06/01/2017] [Indexed: 02/07/2023]
Abstract
Gonadotropin-releasing hormone (GnRH) is a major regulator of reproduction through actions on pituitary gonadotropin release and synthesis. Although it is often thought that pituitary cells are exposed to only one GnRH, multiple GnRH forms are delivered to the pituitary of teleost fishes; interestingly this can include the cGnRH-II form usually thought to be non-hypophysiotropic. GnRHs can regulate other pituitary cell-types, both directly as well as indirectly, and multiple GnRH receptors (GnRHRs) may also be expressed in the pituitary, and even within a single pituitary cell-type. Literature on the differential actions of native GnRH isoforms in primary pituitary cells is largely derived from teleost fishes. This review will outline the diversity and complexity of GnRH-GnRHR signal transduction found within vertebrate gonadotropes as well as extra-gonadotropic sites with special emphasis on comparative studies from fish models. The implications that GnRHR transduction mechanisms are GnRH isoform-, function-, and cell-specific are also discussed.
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Affiliation(s)
- John P Chang
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
| | - Joshua G Pemberton
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
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13
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Yamaguchi Y, Breves JP, Haws MC, Lerner DT, Grau EG, Seale AP. Acute salinity tolerance and the control of two prolactins and their receptors in the Nile tilapia (Oreochromis niloticus) and Mozambique tilapia (O. mossambicus): A comparative study. Gen Comp Endocrinol 2018; 257:168-176. [PMID: 28652133 PMCID: PMC5742082 DOI: 10.1016/j.ygcen.2017.06.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Revised: 05/16/2017] [Accepted: 06/21/2017] [Indexed: 12/15/2022]
Abstract
Osmoregulation in vertebrates is largely controlled by the neuroendocrine system. Prolactin (PRL) is critical for the survival of euryhaline teleosts in fresh water by promoting ion retention. In the euryhaline Mozambique tilapia (Oreochromis mossambicus), pituitary PRL cells release two PRL isoforms, PRL188 and PRL177, in response to a fall in extracellular osmolality. Both PRLs function via two PRL receptors (PRLRs) denoted PRLR1 and PRLR2. We conducted a comparative study using the Nile tilapia (O. niloticus), a close relative of Mozambique tilapia that is less tolerant to increases in environmental salinity, to investigate the regulation of PRLs and PRLRs upon acute hyperosmotic challenges in vivo and in vitro. We hypothesized that differences in the regulation of PRLs and PRLRs underlie the variation in salinity tolerance of tilapias within the genus Oreochromis. When transferred from fresh water to brackish water (20‰), Nile tilapia increased plasma osmolality and decreased circulating PRLs, especially PRL177, to a greater extent than Mozambique tilapia. In dispersed PRL cell incubations, the release of both PRLs was less sensitive to variations in medium osmolality in Nile tilapia than in Mozambique tilapia. By contrast, increases in pituitary and branchial prlr2 gene expression in response to a rise in extracellular osmolality were more pronounced in Nile tilapia relative to its congener, both in vitro and in vivo. Together, these results support the conclusion that inter-specific differences in salinity tolerance between the two tilapia congeners are tied, at least in part, to the distinct responses of both PRLs and their receptors to osmotic stimuli.
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Affiliation(s)
- Yoko Yamaguchi
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, Kaneohe, HI 96744, USA; Department of Biological Science, Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan
| | - Jason P Breves
- Department of Biology, Skidmore College, Saratoga Springs, NY 12866, USA
| | - Maria C Haws
- Pacific Aquaculture and Coastal Resources Center, University of Hawai'i at Hilo, Hilo, HI 96720, USA
| | - Darren T Lerner
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, Kaneohe, HI 96744, USA; Sea Grant College Program, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA
| | - E Gordon Grau
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, Kaneohe, HI 96744, USA
| | - Andre P Seale
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, Kaneohe, HI 96744, USA; Department of Human Nutrition, Food and Animal Sciences, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA.
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14
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Mai TH, Garland EM, Diedrich A, Robertson D. Hepatic and renal mechanisms underlying the osmopressor response. Auton Neurosci 2017; 203:58-66. [PMID: 28143710 DOI: 10.1016/j.autneu.2017.01.007] [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: 08/31/2016] [Revised: 12/09/2016] [Accepted: 01/18/2017] [Indexed: 02/07/2023]
Abstract
Increased blood pressure (BP) is observed in patients with impaired baroreflexes after water drinking. The stimulus for this effect is low blood osmolality, and it has been termed the osmopressor response (OPR). The BP increase is associated with activation of the sympathetic nervous system and a requirement for transient receptor potential vanilloid 4 (TRPV4) channels. However, the mechanisms underlying the OPR are poorly understood. We tested the hypothesis that hypotonicity is sensed in the portal area to initiate the OPR. Sino-aortic denervated mice were used and BP was monitored for 30min after fluid infusion while mice were under anesthesia. Infusion of hypotonic fluid (0.45% saline), but not of isotonic 0.9% saline, directly into the portal vein, produced an immediate OPR (increase in BP with saline 0.45%: 15±13 vs. 0.9%: -7±2mmHg, p=0.003; AUC: 0.45%: 150±99, n=7 vs. 0.9%: -74±60mmHg·min, n=5, p=0.003). However, 0.45% saline was not able to trigger a similar response in TRPV4-/- mice (ΔBPTRPV4: -2±5mmHg, n=8, p=0.009). Hypotonic saline did not raise BP when infused at the same speed and volume into the jugular vein (jugular: -5±6mmHg, p=0.002, compared to portal). Denervation of the splanchnic nerve by celiac ganglionectomy (CGX) did not abolish the OPR (CGX: 15±11 vs. Sham: 16±6mmHg, p=0.34). Renal denervation diminished the OPR elicited by duodenal water infusion (denervation: 9±4 vs. sham: 31±15mmHg, p=0.016). Therefore, hypotonicity in the portal circulation, probably sensed by TRPV4 channels, triggers the OPR and intact renal nerves are needed for the full response.
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Affiliation(s)
- Tu H Mai
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States; Department of Clinical Pharmacology, Vanderbilt University, Nashville, TN, United States
| | - Emily M Garland
- Department of Medicine, Vanderbilt University Medical Center, United States; Department of Clinical Pharmacology, Vanderbilt University, Nashville, TN, United States
| | - André Diedrich
- Department of Medicine, Vanderbilt University Medical Center, United States; Department of Biomedical Engineering, Vanderbilt University, United States; Department of Clinical Pharmacology, Vanderbilt University, Nashville, TN, United States
| | - David Robertson
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States; Department of Medicine, Vanderbilt University Medical Center, United States; Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, United States; Department of Clinical Pharmacology, Vanderbilt University, Nashville, TN, United States.
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15
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Yamaguchi Y, Moriyama S, Lerner DT, Grau EG, Seale AP. Autocrine Positive Feedback Regulation of Prolactin Release From Tilapia Prolactin Cells and Its Modulation by Extracellular Osmolality. Endocrinology 2016; 157:3505-16. [PMID: 27379370 PMCID: PMC6285229 DOI: 10.1210/en.2015-1969] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 06/27/2016] [Indexed: 12/24/2022]
Abstract
Prolactin (PRL) is a vertebrate hormone with diverse actions in osmoregulation, metabolism, reproduction, and in growth and development. Osmoregulation is fundamental to maintaining the functional structure of the macromolecules that conduct the business of life. In teleost fish, PRL plays a critical role in osmoregulation in fresh water. Appropriately, PRL cells of the tilapia are directly osmosensitive, with PRL secretion increasing as extracellular osmolality falls. Using a model system that employs dispersed PRL cells from the euryhaline teleost fish, Oreochromis mossambicus, we investigated the autocrine regulation of PRL cell function. Unknown was whether these PRL cells might also be sensitive to autocrine feedback and whether possible autocrine regulation might interact with the well-established regulation by physiologically relevant changes in extracellular osmolality. In the cell-perfusion system, ovine PRL and two isoforms of tilapia PRL (tPRL), tPRL177 and tPRL188, stimulated the release of tPRLs from the dispersed PRL cells. These effects were significant within 5-10 minutes and lasted the entire course of exposure, ceasing within 5-10 minutes of removal of tested PRLs from the perifusion medium. The magnitude of response varied between tPRL177 and tPRL188 and was modulated by extracellular osmolality. On the other hand, the gene expression of tPRLs was mainly unchanged or suppressed by static incubations of PRL cells with added PRLs. By demonstrating the regulatory complexity driven by positive autocrine feedback and its interaction with osmotic stimuli, these findings expand upon the knowledge that pituitary PRL cells are regulated complexly through multiple factors and interactions.
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Affiliation(s)
- Yoko Yamaguchi
- Hawai'i Institute of Marine Biology (Y.Y., D.T.L., E.G.G., A.P.S.), University of Hawai'i at Mānoa, Kāne'ohe, Hawai'i 96744; School of Marine Biosciences (S.M.), Kitasato University, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan; and University of Hawai'i Sea Grant College Program (D.T.L.) and Department of Human Nutrition, Food and Animal Sciences (A.P.S.), University of Hawai'i at Mānoa, Honolulu, Hawai'i 96822
| | - Shunsuke Moriyama
- Hawai'i Institute of Marine Biology (Y.Y., D.T.L., E.G.G., A.P.S.), University of Hawai'i at Mānoa, Kāne'ohe, Hawai'i 96744; School of Marine Biosciences (S.M.), Kitasato University, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan; and University of Hawai'i Sea Grant College Program (D.T.L.) and Department of Human Nutrition, Food and Animal Sciences (A.P.S.), University of Hawai'i at Mānoa, Honolulu, Hawai'i 96822
| | - Darren T Lerner
- Hawai'i Institute of Marine Biology (Y.Y., D.T.L., E.G.G., A.P.S.), University of Hawai'i at Mānoa, Kāne'ohe, Hawai'i 96744; School of Marine Biosciences (S.M.), Kitasato University, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan; and University of Hawai'i Sea Grant College Program (D.T.L.) and Department of Human Nutrition, Food and Animal Sciences (A.P.S.), University of Hawai'i at Mānoa, Honolulu, Hawai'i 96822
| | - E Gordon Grau
- Hawai'i Institute of Marine Biology (Y.Y., D.T.L., E.G.G., A.P.S.), University of Hawai'i at Mānoa, Kāne'ohe, Hawai'i 96744; School of Marine Biosciences (S.M.), Kitasato University, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan; and University of Hawai'i Sea Grant College Program (D.T.L.) and Department of Human Nutrition, Food and Animal Sciences (A.P.S.), University of Hawai'i at Mānoa, Honolulu, Hawai'i 96822
| | - Andre P Seale
- Hawai'i Institute of Marine Biology (Y.Y., D.T.L., E.G.G., A.P.S.), University of Hawai'i at Mānoa, Kāne'ohe, Hawai'i 96744; School of Marine Biosciences (S.M.), Kitasato University, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan; and University of Hawai'i Sea Grant College Program (D.T.L.) and Department of Human Nutrition, Food and Animal Sciences (A.P.S.), University of Hawai'i at Mānoa, Honolulu, Hawai'i 96822
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16
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Inokuchi M, Breves JP, Moriyama S, Watanabe S, Kaneko T, Lerner DT, Grau EG, Seale AP. Prolactin 177, prolactin 188, and extracellular osmolality independently regulate the gene expression of ion transport effectors in gill of Mozambique tilapia. Am J Physiol Regul Integr Comp Physiol 2015; 309:R1251-63. [PMID: 26377558 DOI: 10.1152/ajpregu.00168.2015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 09/11/2015] [Indexed: 02/03/2023]
Abstract
This study characterized the local effects of extracellular osmolality and prolactin (PRL) on branchial ionoregulatory function of a euryhaline teleost, Mozambique tilapia (Oreochromis mossambicus). First, gill filaments were dissected from freshwater (FW)-acclimated tilapia and incubated in four different osmolalities, 280, 330, 380, and 450 mosmol/kg H2O. The mRNA expression of Na(+)/K(+)-ATPase α1a (NKA α1a) and Na(+)/Cl(-) cotransporter (NCC) showed higher expression with decreasing media osmolalities, while Na(+)/K(+)/2Cl(-) cotransporter 1a (NKCC1a) and PRL receptor 2 (PRLR2) mRNA levels were upregulated by increases in media osmolality. We then incubated gill filaments in media containing ovine PRL (oPRL) and native tilapia PRLs (tPRL177 and tPRL188). oPRL and the two native tPRLs showed concentration-dependent effects on NCC, NKAα1a, and PRLR1 expression; Na(+)/H(+) exchanger 3 (NHE3) expression was increased by 24 h of incubation with tPRLs. Immunohistochemical observation showed that oPRL and both tPRLs maintained a high density of NCC- and NKA-immunoreactive ionocytes in cultured filaments. Furthermore, we found that tPRL177 and tPRL188 differentially induce expression of these ion transporters, according to incubation time. Together, these results provide evidence that ionocytes of Mozambique tilapia may function as osmoreceptors, as well as directly respond to PRL to modulate branchial ionoregulatory functions.
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Affiliation(s)
- Mayu Inokuchi
- Hawaii Institute of Marine Biology, University of Hawaii, Kaneohe, Hawaii; Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo, Japan; and
| | - Jason P Breves
- Department of Biology, Skidmore College, Saratoga Springs, New York
| | - Shunsuke Moriyama
- School of Marine Biosciences, Kitasato University, Sagamihara, Kanagawa, Japan
| | - Soichi Watanabe
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo, Japan; and
| | - Toyoji Kaneko
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo, Japan; and
| | - Darren T Lerner
- Hawaii Institute of Marine Biology, University of Hawaii, Kaneohe, Hawaii; University of Hawaii Sea Grant College Program, University of Hawaii at Manoa, Honolulu, Hawaii
| | - E Gordon Grau
- Hawaii Institute of Marine Biology, University of Hawaii, Kaneohe, Hawaii; University of Hawaii Sea Grant College Program, University of Hawaii at Manoa, Honolulu, Hawaii
| | - Andre P Seale
- Hawaii Institute of Marine Biology, University of Hawaii, Kaneohe, Hawaii
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17
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Gardell AM, Yang J, Sacchi R, Fangue NA, Hammock BD, Kültz D. Tilapia (Oreochromis mossambicus) brain cells respond to hyperosmotic challenge by inducing myo-inositol biosynthesis. ACTA ACUST UNITED AC 2013; 216:4615-25. [PMID: 24072790 DOI: 10.1242/jeb.088906] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
This study aimed to determine the regulation of the de novo myo-inositol biosynthetic (MIB) pathway in Mozambique tilapia (Oreochromis mossambicus) brain following acute (25 ppt) and chronic (30, 60 and 90 ppt) salinity acclimations. The MIB pathway plays an important role in accumulating the compatible osmolyte, myo-inositol, in cells in response to hyperosmotic challenge and consists of two enzymes, myo-inositol phosphate synthase and inositol monophosphatase. In tilapia brain, MIB enzyme transcriptional regulation was found to robustly increase in a time (acute acclimation) or dose (chronic acclimation) dependent manner. Blood plasma osmolality and Na(+) and Cl(-) concentrations were also measured and significantly increased in response to both acute and chronic salinity challenges. Interestingly, highly significant positive correlations were found between MIB enzyme mRNA and blood plasma osmolality in both acute and chronic salinity acclimations. Additionally, a mass spectrometry assay was established and used to quantify total myo-inositol concentration in tilapia brain, which closely mirrored the hyperosmotic MIB pathway induction. Thus, myo-inositol is a major compatible osmolyte that is accumulated in brain cells when exposed to acute and chronic hyperosmotic challenge. These data show that the MIB pathway is highly induced in response to environmental salinity challenge in tilapia brain and that this induction is likely prompted by increases in blood plasma osmolality. Because the MIB pathway uses glucose-6-phosphate as a substrate and large amounts of myo-inositol are being synthesized, our data also illustrate that the MIB pathway likely contributes to the high energetic demand posed by salinity challenge.
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Affiliation(s)
- Alison M Gardell
- Department of Animal Science, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
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