Transcriptional Regulation of Selenoprotein F by Heat Shock Factor 1 during Selenium Supplementation and Stress Response

Abstract

Changes of Selenoprotein F (SELENOF) protein levels have been reported during selenium supplementation, stressful, and pathological conditions. However, the mechanisms of how these external factors regulate SELENOF gene expression are largely unknown. In this study, HEK293T cells were chosen as an in vitro model. The 5′-flanking regions of SELENOF were analyzed for promoter features. Dual-Glo Luciferase assays were used to detect promoter activities. Putative binding sites of Heat Shock Factor 1 (HSF1) were predicted in silico and the associations were further proved by chromatin immunoprecipitation (ChIP) assay. Selenate and tunicamycin (Tm) treatment were used to induce SELENOF up-regulation. The fold changes in SELENOF expression and other relative proteins were analyzed by Q-PCR and western blot. Our results showed that selenate and Tm treatment up-regulated SELENOF at mRNA and protein levels. SELENOF 5′-flanking regions from −818 to −248 were identified as core positive regulatory element regions. Four putative HSF1 binding sites were predicted in regions from −1430 to −248, and six out of seven primers detected positive results in ChIP assay. HSF1 over-expression and heat shock activation increased the promoter activities, and mRNA and protein levels of SELENOF. Over-expression and knockdown of HSF1 showed transcriptional regulation effects on SELENOF during selenate and Tm treatment. In conclusion, HSF1 was discovered as one of the transcription factors that were associated with SELENOF 5′-flanking regions and mediated the up-regulation of SELENOF during selenate and Tm treatment. Our work has provided experimental data for the molecular mechanism of SELENOF gene regulation, as well as uncovered the involvement of HSF1 in selenotranscriptomic for the first time.

Nano-selenium Supplementation Increases Selenoprotein (Sel) Gene Expression Profiles and Milk Selenium Concentration in Lactating Dairy Cows

“…The upregulated GPX mRNA expression and GSH-PX activity that we detected indicated that Sel expression of mammary regulated the activities of milk Se-containing enzyme. It has been reported that the Se levels play a regulatory role for Sels, and Sel expression in animal tissues and cells were induced by Selenium supplement [32][33][34]. Since in the present study, nano-Se supplement resulted in significantly upregulated Sel mRNA expression (GPX, TXNRD, SelW, T, K and F), it is suggested that Se status is an important regulator of selenoprotein activity and expression in the mammary gland of dairy cows.…”

Distinct Roles of SELENOF in Different Human Cancers

“…Moreover, the minor SELENOF haplotype was less responsive to selenium with regard to SECIS-mediated UGA recoding efficiency [ 37 ]. One molecular mechanism of how stressful conditions or selenium availability regulate SELENOF gene expression implicates heat shock factor 1 [ 44 ]. SELENOF resides in the short arm of human chromosome 1 [ 34 ], a region frequently characterized by genetic alterations in cancers [ 36 ], predominantly deletions, indicating that loss of heterozygosity at the SELENOF locus may contribute to the reduction in SELENOF levels or the unmasking of deleterious recessive mutations.…”

Dietary Selenium Supplementation Ameliorates Female Reproductive Efficiency in Aging Mice

“…In addition to Gpxs 1, 3 and 4, our results also revealed a relatively lower expression of Selenof in response to a low-Se diet, whereas its expression was significantly higher in both Se-adequate and Se-supplemented groups. As a "thioredoxin-like" selenoprotein, SELENOF is believed to perform oxidoreductase roles and is differentially expressed under adaptive and acute cellular stress conditions and changes to the Se levels [101][102][103]. It has been shown that, as an ER-resident selenoprotein, SELENOF is implicated in unfolded protein response (UPR), protecting the accumulation of unfolded or misfolded proteins in ER and thereby mitigating ER stress in cells [101].…”

“…In any case, these findings reasonably highlight that expression of Selenof is regulated in a tissue-specific manner and responds differentially to Se levels. Our understanding of the regulation of this selenoprotein, both at transcriptional and translational levels, in different stress-related and pathologic conditions [102,103] is insufficient and further focused studies will help understand its physiological function in detail.…”