Aminoglycoside-driven biosynthesis of selenium-deficient Selenoprotein P

Abstract

Selenoprotein biosynthesis relies on the co-translational insertion of selenocysteine in response to UGA codons. Aminoglycoside antibiotics interfere with ribosomal function and may cause codon misreading. We hypothesized that biosynthesis of the selenium (Se) transporter selenoprotein P (SELENOP) is particularly sensitive to antibiotics due to its ten in frame UGA codons. As liver regulates Se metabolism, we tested the aminoglycosides G418 and gentamicin in hepatoma cell lines (HepG2, Hep3B and Hepa1-6) and in experimental mice. In vitro, SELENOP levels increased strongly in response to G418, whereas expression of the glutathione peroxidases GPX1 and GPX2 was marginally affected. Se content of G418-induced SELENOP was dependent on Se availability, and was completely suppressed by G418 under Se-poor conditions. Selenocysteine residues were replaced mainly by cysteine, tryptophan and arginine in a codon-specific manner. Interestingly, in young healthy mice, antibiotic treatment failed to affect Selenop biosynthesis to a detectable degree. These findings suggest that the interfering activity of aminoglycosides on selenoprotein biosynthesis can be severe, but depend on the Se status, and other parameters likely including age and general health. Focused analyses with aminoglycoside-treated patients are needed next to evaluate a possible interference of selenoprotein biosynthesis by the antibiotics and elucidate potential side effects.

Stop codon context influences genome-wide stimulation of termination codon readthrough by aminoglycosides

“…Simple replacement of selenocysteine with other amino acids has been shown to decrease function of several of these proteins (Axley, Böck, & Stadtman, 1991;Berry, Banu, & Larsen, 1991). Thus, while increased readthrough of UGA codons may generally increase the amount of full-length protein product for these mRNAs, functional levels of selenoproteins may decline with G418 treatment (Renko et al, 2017). While selenocysteine insertion is normally specified by an additional RNA sequence element (SECIS) at particular UGA codons, the extent to which the general availability of selenocysteine tRNA (which normally reads UGA in a cognate fashion) contributes to the relatively higher levels of readthrough of UGA(C) stop codons genome-wide remains unclear.…”

Autoimmunity to selenoprotein P predicts breast cancer recurrence

“…Three complementary Se status biomarkers in the serum samples, i.e., total serum Se and SELENOP concentrations along with GPX3 enzyme activity, have been assessed and were described earlier [ 16 ]. Total reflection X-ray fluorescence (TXRF) was used for total serum Se [ 24 ], a validated sandwich ELISA (selenOtest™-ELISA,selenOmed GmbH, Berlin, Germany) for serum SELENOP concentrations [ 25 , 26 ], and an NADPH-coupled enzymatic test for serum GPX3 activity [ 27 , 28 ]. Inter- and intraassay coefficients of variation were below 15% at all times, as reported earlier [ 16 ].…”

Natural Autoimmunity to Selenoprotein P Impairs Selenium Transport in Hashimoto’s Thyroiditis

“…Translational errors occur during decoding of the ten UGA triplets within the open reading frame [ 25 ], and cysteine can replace selenocysteine during biosynthesis [ 26 ]. Under antibiotic treatment, Se-free selenoproteins can be synthesized [ 27 ]; additionally, tryptophan or arginine may become inserted at UGA codons [ 28 ]. Consequently, the average content of Se per SELENOP molecule has been determined at 5.4 ± 0.5 Se/SELENOP in human [ 29 ], 7.5 Se/Selenop in rat, and 5 Se/Selenop in mouse [ 30 ].…”