Myo-inositol phosphate synthase expression in the European eel (Anguilla anguilla) and Nile tilapia (Oreochromis niloticus): effect of seawater acclimation

Abstract

A single MIPS gene (Isyna1/Ino1) exists in eel and tilapia genomes with a single myo-d-inositol 3-phosphate synthase (MIPS) transcript identified in all eel tissues, although two MIPS spliced variants [termed MIPS(s) and MIPS(l)] are found in all tilapia tissues. The larger tilapia transcript [MIPS(l)] results from the inclusion of the 87-nucleotide intron between exons 5 and 6 in the genomic sequence. In most tilapia tissues, the MIPS(s) transcript exhibits much higher abundance (generally >10-fold) with the exception of white skeletal muscle and oocytes, in which the MIPS(l) transcript predominates. SW acclimation resulted in large (6- to 32-fold) increases in mRNA expression for both MIPS(s) and MIPS(l) in all tilapia tissues tested, whereas in the eel, changes in expression were limited to a more modest 2.5-fold increase and only in the kidney. Western blots identified a number of species- and tissue-specific immunoreactive MIPS proteins ranging from 40 to 67 kDa molecular weight. SW acclimation failed to affect the abundance of any immunoreactive protein in any tissue tested from the eel. However, a major 67-kDa immunoreactive protein (presumed to be MIPS) found in tilapia tissues exhibited 11- and 54-fold increases in expression in gill and fin samples from SW-acclimated fish. Immunohistochemical investigations revealed specific immunoreactivity in the gill, fin, skin, and intestine taken from only SW-acclimated tilapia. Immunofluorescence indicated that MIPS was expressed within gill chondrocytes and epithelial cells of the primary filaments, basal epithelial cell layers of the skin and fin, the cytosol of columnar intestinal epithelial and mucous cells, as well as unknown entero-endocrine-like cells.

Osmolality/salinity-responsive enhancers (OSREs) control induction of osmoprotective genes in euryhaline fish

“…This finding is consistent with the lower salinity tolerance of O. niloticus compared with O. mossambicus (68). However, a recently published article shows that MIPS is still potently induced by salinity stress in O. niloticus (52). Thus, the two remaining copies of OSRE1 and/or another OSRE may be sufficient for potent MIPS induction during salinity stress.…”

Post‐glacial establishment of locally adapted fish populations over a steep salinity gradient

“…The myo‐inositol synthesis pathway is linked to osmoregulation (Gardell et al., 2013; Kalujnaia, Hazon, & Cramb, 2016; Sacchi, Li, Villarreal, Gardell, & Kültz, 2013) and upregulated in response to increased salinity. Myo‐inositol is a small molecule used to adjust cellular osmolality, and by increasing the concentration, organisms can cope with hyperosmotic stress (Burg, Ferraris, & Dmitrieva, 2007).…”

“…The latter is a molecule that provides energy for vasopressin and thus affects membrane permeability allowing for water transport through aquaporin channels (Moeller, Fenton, Zeuthen, & Macaulay, 2009). The myo-inositol synthesis pathway is linked to osmoregulation (Gardell et al, 2013;Kalujnaia, Hazon, & Cramb, 2016;Sacchi, Li, Villarreal, Gardell, & Kültz, 2013) and upregulated in response to increased salinity. Myo-inositol is a small molecule used to adjust cellular osmolality, and by increasing the concentration, organisms can cope with hyperosmotic stress (Burg, Ferraris, & Dmitrieva, 2007).…”

Musashi2 promotes the progression of pancreatic cancer through a novel ISYNA1‐p21/ZEB‐1 pathway

“…8,9 Myoinositol, a kind of water-soluble vitamin synthesized in cells, exhibits various functions, such as seawater acclimation, glucose-lipid metabolism and tumour suppression. [10][11][12][13] Inositol-3-phosphate synthase 1 (ISYNA1) encodes a necessary limit-enzyme in myoinositol biosynthesis and is a direct target of wtp53 in HCT116 and HepG2 cells. 15 Meanwhile, ISYNA1 is closely related with the chemotherapeutic resistance in malignant melanoma.…”