Expression and regulation of mouse selenoprotein P transcript variants differing in non-coding RNA

Abstract

Selenoprotein P (Sepp1), a glycoprotein rich in selenium, is thought to function in selenium transport throughout the body. The sepp1 gene locus potentially produces three alternative transcripts that differ only in their 5' untranslated regions (5'UTRs) and not in their protein coding regions, as indicated by transcript information in genomic databases. Here we investigated the distribution, relative expression, and biological significance of these transcript variants. We confirmed the expression of Sepp1 transcript variants using PCR and sequencing. Using 5'-RACE, we identified multiple 5'-termini upstream from three different splice donor sites, and a single splice acceptor site for exon 2. We found regional and temporal changes in variant expression in select adult and neonate murine tissue and brain regions. Distribution of variants in heart and kidney varied with stage of development. Notably, the Sepp1b variant was localized specifically to the hippocampus in brain. Targeted silencing of individual variants using RNAi demonstrated the biological importance for all transcript variants in cell viability. Additionally, we determined that the Sepp1b variant is a specific target for the miR-7 microRNA by means of its unique 5'UTR structure. Our results emphasize the importance of non-coding transcript variations as a regulatory means for Sepp1 expression in different tissues and stages of development. The presence of a variant localized in the hippocampus and regulated by a microRNA may have implications for the known deficits in synaptic function caused by genetic deletion of Sepp1.

Downregulation of lncRNA TUG1 Affects Apoptosis and Insulin Secretion in Mouse Pancreatic β Cells

“…1, TUG1 is expressed in many tissues, including the brain. Studies have shown that brain-selective kinase2 phosphorylation of PCTAIRE1 negatively regulates glucose-stimulated insulin secretion in pancreatic beta cells [35]. As certain signals in the brain can affect beta cells or GSIS, the in vivo results for blood and insulin may be due to TUG1 knockdown in tissue other than the pancreas.…”

The molecular biology of selenocysteine

“…In an early analysis of Sel P mRNA sequence, conserved regions were found that could potentially regulate SelP incorporation (134). The 5’ untranslated region (5‘UTR) of rat SelP was initially shown to be short (approximately 38 bases) and not very conserved, but a recent study has shown that human SelP exists as three alternative transcripts differing only in their 5‘UTR lengths (135). The smallest 5' UTR (approximately 76 bases) corresponds to the most abundant transcript and also has a target site for micro-RNA mir7 which may potentially play a role in SelP translation efficiency.…”

“…The smallest 5' UTR (approximately 76 bases) corresponds to the most abundant transcript and also has a target site for micro-RNA mir7 which may potentially play a role in SelP translation efficiency. The 5‘UTR of the 3 transcripts were predicted to fold with varying secondary structure complexity and it was speculated that this variation could in turn alter rate and efficiency of SelP translation (135). …”

Role of microRNA-7 and selenoprotein P in hepatocellular carcinoma

“…MicroRNA-7 (miR-7) has been proven to play a substantial role in tumorigenesis and to progress by several signaling pathways in various tumors, but its functions in the context of HCC need further study and investigation. [11][12][13][14] The selected miR-7 was analyzed by miRcode database (available at http://www.mircode.org/?gene=sepp1&mirfam=miR-7%2F7ab&class=&cons=&trregion) and based on previous study of Dewing et al, 15 where selenoprotein P (SeP) was selected as miR-7 target pair. SeP was retrieved and confirmed as an associated gene with HCC from gene atlas database (available at http://genatlas.medecine.univ-paris5.…”