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An osmolality/salinity-responsive enhancer 1 (OSRE1) in intron 1 promotes salinity induction of tilapia glutamine synthetase.

ABSTRACT: Euryhaline tilapia (Oreochromis mossambicus) are fish that tolerate a wide salinity range from fresh water to > 3× seawater. Even though the physiological effector mechanisms of osmoregulation that maintain plasma homeostasis in fresh water and seawater fish are well known, the corresponding molecular mechanisms that control switching between hyper- (fresh water) and hypo-osmoregulation (seawater) remain mostly elusive. In this study we show that hyperosmotic induction of glutamine synthetase represents a prominent part of this switch. Proteomics analysis of the O. mossambicus OmB cell line revealed that glutamine synthetase is transcriptionally regulated by hyperosmolality. Therefore, the 5' regulatory sequence of O. mossambicus glutamine synthetase was investigated. Using an enhancer trapping assay, we discovered a novel osmosensitive mechanism by which intron 1 positively mediates glutamine synthetase transcription. Intron 1 includes a single, functional copy of an osmoresponsive element, osmolality/salinity-responsive enhancer 1 (OSRE1). Unlike for conventional enhancers, the hyperosmotic induction of glutamine synthetase by intron 1 is position dependent. But irrespective of intron 1 position, OSRE1 deletion from intron 1 abolishes hyperosmotic enhancer activity. These findings indicate that proper intron 1 positioning and the presence of an OSRE1 in intron 1 are required for precise enhancement of hyperosmotic glutamine synthetase expression.

SUBMITTER: Kim C

PROVIDER: S-EPMC7374092 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature

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An osmolality/salinity-responsive enhancer 1 (OSRE1) in intron 1 promotes salinity induction of tilapia glutamine synthetase.

Kim Chanhee C Kültz Dietmar D

Scientific reports 20200721 1

Euryhaline tilapia (Oreochromis mossambicus) are fish that tolerate a wide salinity range from fresh water to > 3× seawater. Even though the physiological effector mechanisms of osmoregulation that maintain plasma homeostasis in fresh water and seawater fish are well known, the corresponding molecular mechanisms that control switching between hyper- (fresh water) and hypo-osmoregulation (seawater) remain mostly elusive. In this study we show that hyperosmotic induction of glutamine synthetase re ...[more]

PMID: 32694739

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Project description:In this study, RNA-Seq was used to reveal the differences of molecular pathways in hepatopancreas of O. niloticus adapated to water with salinity of 8 or 16 practical salinity (psu), respectively, with fish at freshwater as the control,. Significantly changed pathways were mainly related to lipid metabolism, glucose utilization, protein consumption, osmotic regulation, signal transduction and immunology. Based on the tendencies from freshwater to 8 or 16 psu, the differentially expressed gene unions were categorized into eight unique models, which were further classified into three categories which were constant-change (either keep increasing or decreasing), change-then-stable and stable-then-change. In constant-change category, steroid biosynthesis, steroid hormone biosynthesis, fat digestion and absorption, complement and coagulation cascades were extremely significantly affected by ambient salinity (P < 0.01), indicating that these pathways play pivotal roles in molecular response to salinity acclimation from freshwater to saline water in O. niloticus, and should be the main research focus in the future. In change-then-stable category, ribosome, oxidative phosphorylation, peroxisome proliferator-activated receptors (PPAR) signaling pathway, fat digestion and absorption changed significantly with ambient increasing salinity (P < 0.01), showing these pathways were sensitive to environmental salinity variation, but had a response threshold, and would stop changing once salinity exceeds the threshold. In stable-then-change category, protein export, protein processing in endoplasmic reticulum, tight junction, thyroid hormone synthesis, antigen processing and presentation, glycolysis/gluconeogenesis and glycosaminoglycan biosynthesis - keratan sulfate were the top changed pathways (P < 0.01), suggesting that these pathways were not sensitive to salinity variation, but these pathways will respond significantly under salinity exceeding a certain level. The pathways and genes reported in this study laid on a solid foundation for future studies in understanding the underlying mechanism for salinity adaptation of freshwater fish. Examination of 3 different salinities treated hepatopancreas in Nile tilapia

Dataset Information

An osmolality/salinity-responsive enhancer 1 (OSRE1) in intron 1 promotes salinity induction of tilapia glutamine synthetase.

Publications

An osmolality/salinity-responsive enhancer 1 (OSRE1) in intron 1 promotes salinity induction of tilapia glutamine synthetase.

Similar Datasets

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