Expression and Regulation of the Vitamin D Receptor in the Zebrafish, Danio rerio

Abstract

Vitamin D and vitamin D metabolites such as 25(OH) 2 D 3 ] circulate in the serum of fish. The receptor for 1␣,25(OH) 2 D 3 (VDR) has previously been cloned from fish intestine, and ligand binding assays have shown the presence of the VDR in the gills, intestine, and liver of fish. Using immunohistochemical methods with specific antibodies against the VDR, we now report that the VDR is widely expressed in tissues of the adult male and female zebrafish, Danio rerio, specifically in epithelial cells of gills, tubular cells of the kidney, and absorptive cells in the intestine. Additionally, the VDR is expressed in the skin, the olfactory organ, the retina, brain, and spinal cord. Sertoli cells of the testis, oocytes, acinar cells of the pancreas, hepatocytes, and bile duct epithelial cells express substantial amounts of the receptor. Osteoblast-like cells and chondrocytes also express VDR. Preimmune serum and antiserum preadsorbed with Danio VDR protein fails to detect VDR in the same tissues. The VDR is also present in the developing eye, brain, and otic vesicle of 48-and 96-h postfertilization zebrafish embryos. Parenteral administration of 1␣,25(OH) 2 D 3 increases concentrations of VDR in intestinal epithelial cells but not in epithelial cells of the gills. Lithocholic acid, however, does not alter concentrations of VDR after parenteral administration. The data suggest that VDR is widely distributed in tissues of the zebrafish, D. rerio, and is likely to play important roles in epithelial transport, bone, and endocrine function. Furthermore, concentrations of the receptor seem to be regulated by its ligand, 1␣,25-dihydroxyvitamin D but not by lithocholic acid. Zebrafish may serve as a useful model in which to assess the function of the VDR in diverse tissues.

Vitamin D: calcium and bone homeostasis during evolution

“…42 VDR is widely expressed in nearly all zebrafish tissues-not only related to calcium transport such as gills, kidney and intestine but also in bone and many endocrine tissues, brain and other tissues-starting already early in its embryonic development. 39,43 Such widespread distribution of VDR was also found in other fish such as rainbow trout. 44 1,25(OH) 2 D 3 also regulates the calcium-transporting transient receptor protein (TRP) genes and thereby increases calcium influx and the calcium content of zebrafish embryos 45,46 and rainbow trout.…”

Effects of dietary vitamin D3 administration on innate immune parameters of seabream (Sparus aurata L.)

“…The few studies that have been carried out on fish deal with the metabolic transformation of the vitamin in both liver and kidney [2,14,[30][31][32], the establishment of plasma levels of vitamin D metabolites [12,13,33,34], the identification of vitamin D plasma binding protein [35,36] and the expression, regulation and evolution of vD receptor in different organs [26,[37][38][39].…”

Fundamental Approaches to the Study of Zebrafi sh Nutrition

“…Mehrad and colleagues (2011) reported that inclusion of ascorbic acid at levels of 1000 mg/kg of feed increased growth rates, body weight, and fecundity in zebrafish. Vitamin D and its metabolites circulate in the blood of the zebrafish, and receptors for this vitamin are widely distributed in many tissues (Craig et al 2008), suggesting its potential importance as a dietary nutrient (Miller et al 2010). Lebold and colleagues (2011) fed zebrafish diets that were deficient in vitamin E (alpha-tocopherol); survival of offspring of deficient adults was lower, malformations resulted, and fatty acid profiles were altered, indicating the importance of vitamin E as a nutrient.…”