Biotin Regulates the Expression of Holocarboxylase Synthetase in the miR-539 Pathway in HEK-293 Cells

Abstract

Holocarboxylase synthetase (HCS) catalyzes the covalent binding of biotin to carboxylases and histones. In mammals, the expression of HCS depends on biotin, but the mechanism of regulation is unknown. Here we tested the hypothesis that microRNA (miR) plays a role in the regulation of the HCS gene. Human embryonic kidney cells were used as the primary model, but cell lines from other tissues and primary human cells were also tested. In silico searches revealed an evolutionary conserved binding site for miR-539 in the 3 prime -untranslated region (3 prime -UTR) of HCS mRNA. Transgenic cells and reporter gene constructs were used to demonstrate that miR-539 decreases the expression of HCS at the level of transcription rather than translation; these findings were corroborated in nontransgenic cells. When miR-539 was overexpressed in transgenic cells, the abundance of both HCS and biotinylated histones decreased. The abundance of miR-539 was tissue dependent: fibroblasts gt kidney cells gt intestinal cells gt lymphoid cells. Dose-response studies revealed that the abundance of miR-539 was significantly higher at physiological concentrations of biotin than both biotin-deficient and biotin-supplemented media in all cell lines tested. In kidney cells, the expression of HCS was lower in cells in physiological medium than in deficient and supplemented medium. In contrast, in fibroblasts, lymphoid cells, and intestinal cells, there was no apparent link between miR-539 abundance and HCS expression, suggesting that factors other than miR-539 also contribute to the regulation of HCS expression in some tissues. Collectively, the results of this study suggest that miR-539 is among the factors sensing biotin and regulating HCS.

MiR-539 inhibits thyroid cancer cell migration and invasion by directly targeting CARMA1

“…However, to our knowledge, only three reports have described the function of miR-539. Firstly, one study found that miR-539 is among the factors sensing cellular biotin levels and targets holocarboxylase synthetase (HCS) [18]. Secondly, miR-539 has been reported to suppress O-GlcNAcase expression and to play an important role in the failing heart [19].…”

Nutrition, Histone Epigenetic Marks, and Disease

“…(b) The human HLCS promoter has been tentatively identified (Warnatz et al 2010) but not yet characterized in great detail. (c) The expression of HLCS is repressed by miR-539 (Bao et al 2010). (d) HLCS-dependent histone biotinylation cross talks with cytosine methylation in gene regulation.…”

The Emerging Role of MicroRNAs in the Regulation of Gene Expression by Nutrients

“…Additionally, it was found that the expression of the holocarboxylase synthetase enzyme responsible for attaching biotin to the carboxylases is regulated by miR-539 and miR-153 [45,46]. …”

“…Biotin deficiency (vitamin H or vitamin B 7 ) has been shown to alter carbon metabolism gene expression in three different eukaryotes (yeast, worm, and rat [44]), and a decrease in the expression of miR-539 is observed under these circumstances [45]. Additionally, it was found that the expression of the holocarboxylase synthetase enzyme responsible for attaching biotin to the carboxylases is regulated by miR-539 and miR-153 [45,46].…”