Salinity Modifies Hepatic Outer‐Ring Deiodinating Activity in <i>Fundulus heteroclitus</i>

Orozco, Aurea; Linser, Paul J.; Valverde-R, R. Carlos

doi:10.1111/j.1749-6632.1998.tb10815.x

Cited by 9 publications

(8 citation statements)

References 3 publications

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“…Discussion This work confirms and extends previous preliminary results (Orozco et al, 1998) showing that killifish hepatic D2 increases during hypo-osmotic stress. Indeed, the present studies demonstrate that to cope with a sudden drop in salinity, the liver of killifish triggers a homeostatic response in which a putative OREBP kinase-activated pathway stimulates D2 transcription and enzymatic activity.…”

Section: López-bojórquez and Otherssupporting

confidence: 82%

“…Indeed TH have been thought to support long-term adaptive responses mediated by growth hormone, prolactin and cortisol, among other classical osmoregulatory messengers (Sakamoto and McCormick, 2006). However, previous studies from our laboratory (Orozco et al, 1998;Orozco et al, 2002b) and recent studies in the seabream gill (Klaren et al, 2007), strongly suggest a more direct involvement of TH in the hydro-osmotic balance in fish. Furthermore, our present results support the suggestion that a putative hypo-osmotic, OREBP-mediated increase in hepatic D2 activity could be an important endocrine component for the maintenance of hydro-osmotic homeostasis in fish.…”

Section: López-bojórquez and Othersmentioning

confidence: 44%

“…Nevertheless, the function of TH in hydro-osmotic balance in fish has been a controversial issue (for reviews, see McCormick, 2001;Orozco and Valverde-R., 2005;Klaren et al, 2007). Previous data from our laboratory have shown that in the euryhaline teleost Fundulus heteroclitus (Fh), hypo-osmotic stress elicits an increase in liver iodothyronine deiodinase type 2 (D2) activity (Orozco et al, 1998). D2 is known to be the major provider of T 3 at the target cell level; thus, an upregulation of this enzyme after an osmotic challenge suggested the participation of TH during this homeostatic response.…”

Section: Introductionmentioning

confidence: 99%

“…Except for the change in water salinity, control and experimental groups were handled in the same manner. Based on previous experiments (Orozco et al, 1998), fish were sacrificed 0.5, 1, 2, 4, 6, 8, 12 and 16·h after the hypoosmotic challenge. Animals were sacrificed by decapitation, and the liver was collected and divided to measure D2 mRNA concentrations, D2 activity and for nuclear extraction (see below).…”

Section: In Vivo Experimentsmentioning

confidence: 99%

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Functional identification of an osmotic response element (ORE) in the promoter region of the killifish deiodinase 2 gene (FhDio2)

López-Bojórquez

Villalobos

Garcı́a-G

et al. 2007

Journal of Experimental Biology

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SUMMARY The physiological role played by thyroid hormones (TH) in hydro-osmotic homeostasis in fish remains a controversial issue. Previous studies have shown that in Fundulus heteroclitus (killifish) hypo-osmotic stress increases liver iodothyronine deiodinase type 2 (D2) mRNA and D2 activity. In this study we identified two conserved osmotic response element (ORE) motifs in the promoter region of the killifish D2 gene (FhDio2) and examined their possible role in the transcriptional regulation of FhDio2during hypo-osmotic stress. As assessed by the electrophoretic mobility shift assay, results from in vivo and in vitro experiments demonstrate that exposure to an abrupt hyposmotic challenge triggers in the liver of killifish a strong nuclear recruitment of a putative osmotic response element binding protein (OREBP). This protein–DNA binding is time-dependent, attains a maximum within 2–8 h after the osmotic stress,and is followed by a significant increase in D2 activity. Furthermore,protein–DNA binding and the subsequent elevation in enzyme activity were blocked by the tyrosine kinase inhibitor genistein. Thus, during hypo-osmotic stress, a putative OREBP kinase-activated pathway stimulates FhDio2transcription and enzymatic activity. These data and the fact that D2 is the major enzyme providing local intracellular T3 suggest that TH plays a direct role in osmoregulation in fish, possibly by participating in hepatic ammonia metabolism. This study provides important insight into the physiological role of TH in hydro-osmotic homeostasis in fish.

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Section: López-bojórquez and Otherssupporting

confidence: 82%

Section: López-bojórquez and Othersmentioning

confidence: 44%

Section: Introductionmentioning

confidence: 99%

Section: In Vivo Experimentsmentioning

confidence: 99%

See 2 more Smart Citations

Functional identification of an osmotic response element (ORE) in the promoter region of the killifish deiodinase 2 gene (FhDio2)

López-Bojórquez

Villalobos

Garcı́a-G

et al. 2007

Journal of Experimental Biology

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“…Cortisol stimulated the conversion, by ORD, of T 4 to T 3 in Salvelinus fontinalis liver in vitro (Vijayan et al 1988), and enhanced liver D1 and D2 activities in Fundulus heteroclitus (Orozco et al 1998). Negative results have also been reported, i.e.…”

Section: Introductionmentioning

confidence: 71%

Effects of cortisol and thyroid hormone on peripheral outer ring deiodination and osmoregulatory parameters in the Senegalese sole (Solea senegalensis)

Arjona¹,

Vargas‐Chacoff²,

Río³

et al. 2011

Journal of Endocrinology

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The thyroid gland in fish mainly secretes the thyroid prohormone 3,5,3 0 ,5 0 -tetraiodothyronine (T 4 ), and extrathyroidal outer ring deiodination (ORD) of the prohormone to 3,5,3 0 -triiodothyronine (T 3 ) is pivotal in thyroid hormone economy. Despite its importance in thyroid hormone metabolism, factors that regulate ORD are still largely unresolved in fish. In addition, the osmoregulatory role of T 3 is still a controversial issue in teleosts. In this study, we investigated the regulation of the ORD pathway by cortisol and T 3 in different organs (liver, kidney, and gills) of Solea senegalensis and the involvement of T 3 in the control of branchial and renal Na C , K C -ATPase activity, a prime determinant of the hydromineral balance in teleosts. Animals were treated with i.p. slow-release coconut oil implants containing cortisol or T 3 . Hepatic and renal ORD activities were up-regulated in cortisol-injected animals. T 3 -treated fish showed a prominent decrease in plasma-free T 4 levels, whereas ORD activities did not change significantly. Branchial and renal Na C , K C -ATPase activities were virtually unaffected by T 3 , but were transiently up-regulated by cortisol. We conclude that cortisol regulates local T 3 bioavailability in S. senegalensis via ORD in an organ-specific manner. Unlike T 3 , cortisol appears to be directly implicated in the up-regulation of branchial and renal Na

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Effects of acclimation salinity on the expression of selenoproteins in the tilapia, Oreochromis mossambicus

Seale

Gilman

Moorman

et al. 2014

Journal of Trace Elements in Medicine and Biology

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Selenoproteins are ubiquitously expressed, act on a variety of physiological redox-related processes, and are mostly regulated by selenium levels in animals. To date, the expression of most selenoproteins has not been verified in euryhaline fish models. The Mozambique tilapia, Oreochromis mossambicus, a euryhaline cichlid fish, has a high tolerance for changes in salinity and survives in fresh water (FW) and seawater (SW) environments which differ greatly in selenium availability. In the present study, we searched EST databases for cichlid selenoprotein mRNAs and screened for their differential expression in FW and SW-acclimated tilapia. The expression of mRNAs encoding iodothyronine deiodinases 1, 2 and 3 (Dio1, Dio2, Dio3), Fep15, glutathione peroxidase 2, selenoproteins J, K, L, M, P, S, and W, was measured in the brain, eye, gill, kidney, liver, pituitary, muscle, and intraperitoneal white adipose tissue. Gene expression of selenophosphate synthetase 1, Secp43, and selenocysteine lyase, factors involved in selenoprotein synthesis or in selenium metabolism, were also measured. The highest variation in selenoprotein and synthesis factor mRNA expression between FW- and SW-acclimated fish was found in gill and kidney. While the branchial expression of Dio3 was increased upon transferring tilapia from SW to FW, the inverse effect was observed when fish were transferred from FW to SW. Protein content of Dio3 was higher in fish acclimated to FW than in those acclimated to SW. Together, these results outline tissue distribution of selenoproteins in FW and SW-acclimated tilapia, and indicate that at least Dio3 expression is regulated by environmental salinity.

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Salinity Modifies Hepatic Outer‐Ring Deiodinating Activity in Fundulus heteroclitus

Cited by 9 publications

References 3 publications

Functional identification of an osmotic response element (ORE) in the promoter region of the killifish deiodinase 2 gene (FhDio2)

Functional identification of an osmotic response element (ORE) in the promoter region of the killifish deiodinase 2 gene (FhDio2)

Effects of cortisol and thyroid hormone on peripheral outer ring deiodination and osmoregulatory parameters in the Senegalese sole (Solea senegalensis)

Effects of acclimation salinity on the expression of selenoproteins in the tilapia, Oreochromis mossambicus

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