Spatiotemporal expression of the selenoprotein P genein postimplantational mouse embryos

Abstract

Selenoprotein P (Sepp) is an extracellular glycoprotein which functions principally as a selenium (Se) transporter and antioxidant. In order to assess the spatiotemporal expression of the Sepp gene during mouse embryogenesis, quantitative RT-PCR and in situ hybridization analyses were conducted in embryos and extraembryonic tissues, including placenta. Sepp mRNA expression was detected in all embryos and extraembryonic tissues on embryonic days (E) 7.5 to 18.5. Sepp mRNA levels were high in extraembryonic tissues, as compared to embryos, on E 7.5-13.5. However, the levels were higher in embryos than in extraembryonic tissues on E 14.5-15.5, but were similar in both tissues during the subsequent periods prior to birth. According to the results of in situ hybridization, Sepp mRNA was expressed principally in the ectoplacental cone and neural ectoderm, including the neural tubes and neural folds. In whole embryos, Sepp mRNA was expressed abundantly in nervous tissues on E 9.5-12.5. Sepp mRNA was also expressed in forelimb and hindlimb buds on E 10.5-12.5. In the sectioned embryos, on E 13.5-18.5, Sepp mRNA was expressed persistently in the developing limbs, gastrointestinal tract, nervous tissue, lung, kidney and liver. On E 16.5-18.5, Sepp mRNA expression in the submandibular gland, whisker follicles, pancreas, urinary bladder and skin was apparent. In particular, Sepp mRNA was detected abundantly in blood cells during all the observed developmental periods. These results show that Sepp may function as a transporter of selenium, as well as an antioxidant, during embryogenesis.

Selenoprotein P regulation by the glucocorticoid receptor

“…Spatiotemporal expression of Sepp was observed in the central nervous system, limb buds, blood cells, lung, liver, intestine, testis, and developing epithelia, as well as in extraembryonic tissues, during organogenesis. The authors suggest that this increase in Sepp may provide antioxidant protection against the reactive oxygen species formed during embryogenesis, as well as provide a transplacental or intraembyronic selenium transport function (Lee et al 2008). Additional evidence supporting a role for SelP in growth and development includes observations from the SelP knockout mouse, which displays a phenotype that includes growth retardation, neurological impairment, and male infertility (Hill et al 2003; Schomburg et al 2003; Renko et al 2008).…”

“…Elegant developmental studies have demonstrated SEPP1 ortholog spatiotemporal expression in both zebrafish (Thisse et al 2003) and murine model systems (Lee et al 2008). Increased expression has been observed in differentiating myeloid, pulmonary, and Sertoli cells (Tabuchi et al 2005; Ghassabeh et al 2006; Wade et al 2006).…”

Localization and regulation of pancreatic selenoprotein P

“…We hypothesized that b-cells may possess an additional antioxidant protein, Sepp1, as the presence of Sepp1 mRNA has been demonstrated before in the rodent pancreas and in b-cells (Niwa et al 1997, Lee et al 2008. As both Sepp1 and GPx1 mRNA have been detected in liver and kidney at high copy numbers (Hoffmann et al 2007), we first compared their gene expression in liver, kidney, and pancreas taken from rats fed a Se-adequate standard diet.…”

“…Knockdown of Sepp1 biosynthesis in astrocytes and in adipocytes has been shown to increase their sensitivity for oxidative damage (Steinbrenner et al 2006, Zhang & Chen 2011. Sepp1 mRNA has also been detected in the mouse pancreas (Lee et al 2008), where it has been described to be enriched in b-cells compared with a-cells of islets (Niwa et al 1997).…”

The Relationship between Selenoprotein P and Glucose Metabolism in Experimental Studies

“…Pancreatic expression in rodents is restricted to the islets and endocrine cell lines, is not produced in the exocrine pancreas tissue [32,33,34] and appears to be co-localized with both insulin and glucagon by immunofluorescence [32]; however, it is expressed more strongly in beta-cells than in alpha-cells [34]. Additionally, no secreted Sepp1 isoforms were detected in the supernatant from the rat insulinoma cell INS-1, which suggests that Sepp1 produced by pancreatic cells does not function as an external secretion as does liver.…”