skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Transcriptional up-regulation of the myo -inositol biosynthesis pathway is enhanced by NFAT5 in hyperosmotically stressed tilapia cells
Title: Transcriptional up-regulation of the myo -inositol biosynthesis pathway is enhanced by NFAT5 in hyperosmotically stressed tilapia cells
Euryhaline fish experience variable osmotic environments requiring physiological adjustments to tolerate elevated salinity. Mozambique tilapia ( Oreochromis mossambicus) possess one of the highest salinity tolerance limits of any fish. In tilapia and other euryhaline fish species the myo-inositol biosynthesis (MIB) pathway enzymes, myo-inositol phosphate synthase (MIPS) and inositol monophosphatase 1 (IMPA1.1), are among the most upregulated mRNAs and proteins indicating the high importance of this pathway for hyper-osmotic (HO) stress tolerance. These abundance changes must be precluded by HO perception and signaling mechanism activation to regulate the expression of MIPS and IMPA1.1 genes. In previous work using a O. mossambicus cell line (OmB), a reoccurring osmosensitive enhancer element (OSRE1) in both MIPS and IMPA1.1 was shown to transcriptionally upregulate these enzymes in response to HO stress. The OSRE1 core consensus (5'-GGAAA-3') matches the core binding sequence of the predominant mammalian HO response transcription factor, nuclear factor of activated T-cells (NFAT5). HO challenged OmB cells showed an increase in NFAT5 mRNA suggesting NFAT5 may contribute to MIB pathway regulation in euryhaline fish. Ectopic expression of wild-type NFAT5 induced an IMPA1.1 promoter-driven reporter by 5.1-fold (p < 0.01). Moreover, expression of dominant negative NFAT5 in HO media resulted in a 47% suppression of the reporter signal (p<0.005). Furthermore, reductions of IMPA1.1 (37-49%) and MIPS (6-37%) mRNA abundance were observed in HO challenged NFAT5 knockout cells relative to control cells. Collectively, these multiple lines of experimental evidence establish NFAT5 as a tilapia transcription factor contributing to HO induced activation of the MIB pathway.  more » « less
Award ID(s):
2209383
PAR ID:
10524873
Author(s) / Creator(s):
; ;
Publisher / Repository:
American Physiological Society
Date Published:
Journal Name:
American Journal of Physiology-Cell Physiology
ISSN:
0363-6143
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; (, SICB Virtual Annual Meeting 2021)
    null (Ed.)
    Euryhaline fish tolerate a wide range of environmental salinity by employing molecular mechanisms for coping with the associated osmotic stress. We have previously shown that osmotic stress transcription factor 1 (OSTF1) is part of these mechanisms. OSTF1 is transiently and rapidly upregulated in gill epithelial cells of tilapia (Oreochromis mossambicus) exposed to hyperosmolality. Hyperosmotic induction of OSTF1 in tilapia gills was reproduced in the tilapia OmB cell neuroepithelial cell line. OSTF1 shares the signature sequence of the TSC-22 family suggesting that it is a transcriptional repressor. If, in fact, OSTF1 is a transcription factor, we hypothesize that it will localize to the nucleus during hyperosmotic stress. Using standard cloning procedures, OSTF1 was tagged with enhanced green fluorescent protein (EGFP) at either the C- or N-terminus. Using fluorescent microscopy we show that the fusion proteins are retained in the cytosol under iso-osmotic conditions. To evaluate potential nuclear translocation of OSTF1 during hyperosmotic stress, we subjected OmB cells expressing the OSTF1:EGFP fusion protein to hyperosmotic media and imaged at time intervals from 5 minutes to 4 hours using a Leica Dmi8 microscope with automated scanning stage. At four hours and 650 mOsmol/kg, subcellular localization quantified by LASX image analysis (Leica) demonstrated that OSTF1:EGFP was mostly localized to the nucleus. This result supports our hypothesis that OSTF1 is indeed an osmotically inducible transcription factor. Current work evaluates influence of specific OSTF1 domains on nuclear localization. 
    more » « less
  2. (, ICBF Proceeedings)
    Aquatic animals existing in variable salinity environments must possess mechanisms to maintain cellular osmotic balance essential for function. When facing hyper-osmotic stress, some cells can produce biochemically inert compatible organic osmolytes, such as myoinositol, to combat the osmotic gradient across the cell membrane. Myo-inositol is commonly utilized in this manner across widely diverse taxa. The final enzyme in the myo-inositol synthesis pathway is IMPA1.1 which has been shown to be highly upregulated in multiple tissues in several fish species in response to hyperosmotic challenge including Oreochromis mossambicus, a teleost fish tolerant of extreme hypersaline conditions. When the regulatory region of IMPA1.1 from this species was cloned upstream of multiple reporter genes and transfected into cell cultures, high reporter activity was observed in cells of both this species and a distantly related species, suggesting high conservation of regulatory elements and utilization of a common hyperosmotic response signaling pathway. Current work includes further genetic manipulations of this pathway in cell culture models to decipher its components from cellular osmosensing leading to differential regulation of relevant genes. Supported by NSF award 1656371 and BARD award IS-4800-15 R. 
    more » « less
  3. ; ; ; (, Frontiers in Aging)
    null (Ed.)
    Euryhaline teleost fish are characterized by their ability to tolerate a wide range of environmental salinities by modifying the function of osmoregulatory cells and tissues. In this study, we experimentally addressed the age-related decline in the sensitivity of osmoregulatory transcripts associated with a transfer from fresh water (FW) to seawater (SW) in the euryhaline teleost, Mozambique tilapia, Oreochromis mossambicus . The survival rates of tilapia transferred from FW to SW were inversely related with age, indicating that older fish require a longer acclimation period during a salinity challenge. The relative expression of Na + /K + /2Cl − cotransporter 1a ( nkcc1a ), which plays an important role in hyposmoregulation, was significantly upregulated in younger fish after SW transfer, indicating a clear effect of age in the sensitivity of branchial ionocytes. Prolactin (Prl), a hyperosmoregulatory hormone in O. mossambicus , is released in direct response to a fall in extracellular osmolality. Prl cells of 4-month-old tilapia were sensitive to hyposmotic stimuli, while those of >24-month-old fish did not respond. Moreover, the responsiveness of branchial ionocytes to Prl was more robust in younger fish. Taken together, multiple aspects of osmotic homeostasis, from osmoreception to hormonal and environmental control of osmoregulation, declined in older fish. This decline appears to undermine the ability of older fish to survive transfer to hyperosmotic environments. 
    more » « less
  4. ; ; ; (, Scientific Reports)
    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, Prl188and 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 ofprl188increased with rising temperatures at lower osmolalities, while andprl177decreased 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,stat1aandnfat1c, known to regulateprl188andprl177,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. 
    more » « less
  5. ; (, Panorama Public)
    Histone post-translational modifications (PTMs) are epigenetic marks that can be induced by environmental stress and elicit heritable patterns of gene expression. To investigate this process in an ecological context, we characterized the influence of salinity stress on histone PTMs within the gills, kidney, and testes of Mozambique tilapia (Oreochromis mossambicus). A total of 503 histone PTMs were quantified in each tissue sample and compared between freshwater-adapted fish exposed to salinity treatments that varied in intensity and duration. Three salinity-responsive histone PTMs were identified in this study. When freshwater-adapted fish were exposed to seawater for two hours, the relative abundance of H1K16ub significantly increased in the gills. Long-term salinity stress elicited changes in an additional two histone PTMs in the testes. When freshwater-adapted fish were exposed to a pulse of severe salinity stress, where salinity reached a maximum of 82.5 g/kg, the relative abundance of H3K14ac and H3K18ub decreased significantly in the testes. This study demonstrates that specific types of salinity stress can alter histone PTMs in Mozambique tilapia, both in an osmoregulatory organ and in the germ line. These results signify a potential for histone PTMs to be involved in salinity acclimation and adaptation in euryhaline fishes, thereby adding to a growing body of evidence that epigenetic mechanisms are involved in such processes. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email