{"id":1206,"date":"2019-07-02T18:07:37","date_gmt":"2019-07-02T10:07:37","guid":{"rendered":"http:\/\/www.bioactivescreeninglibrary.com\/?p=1206"},"modified":"2022-01-07T10:53:49","modified_gmt":"2022-01-07T02:53:49","slug":"penultimate-sec-participates-intramolecular-sl1-sels-functional-sre-identified","status":"publish","type":"post","link":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/2019\/07\/02\/penultimate-sec-participates-intramolecular-sl1-sels-functional-sre-identified\/","title":{"rendered":"The penultimate Sec participates in an intramolecular the SL1 within SelS is the second functional SRE to be identified"},"content":{"rendered":"

In addition to its function as a putative SRE, the formation of SL1 has an additional consequence in primates. RNA structures are well known to ASP1517<\/a> influence mRNA splicing. The 59 splice site responsible for generating the SelS variant 1 mRNA is sequestered in the double-stranded stem of SL1, preventing the splicing event. Thus, factors that influence the formation of SL1 have the potential to regulate the production of SelS variant 1 mRNAs, which cannot produce the Sec-containing SelS protein. The 140 nucleotides region downstream of the SelS SECIS element harbors sequences that strongly inhibit Sec insertion. Within this region, one candidate is SL2, which is predicted to form immediately downstream of the SECIS element. There are different mechanisms one can envision for how the presence of this conserved element might influence Sec insertion. The presence of a stable stem-loop immediately adjacent to the SECIS element may weaken the interactions at the base of the SECIS element, interfering with its ability to form or causing destabilization. SL2 also displays an ARE, which are known to modulate transcript stability and translational control, both positively and negatively. The selenoprotein Thioredoxin reductase 1 contains AREs in its 39UTR that destabilize that mRNA. However, the effects of AREs are transcript-specific, as are the protein factors that often mediate their effects. The ARE in SelS does not affect the stability of the mRNA and further studies will be required to determine the mechanism by which the SelS ARE inhibits Sec insertion. Given our findings, many of the results from previous studies on SelS need to be reinterpreted. With respect to RNA-based experiments, several studies used RT-PCR to examine SelS mRNA levels in human cell lines under various conditions. However the majority of these studies were published before the two RNA variants were annotated. Most use primer pairs in the 39UTR of the variant 2 mRNA to examine SelS levels. In some cases this results in an underrepresentation of SelS mRNA levels. It is also not clear that both variants will respond similarly to stresses. In the case of SelS protein studies, similar caveats exist. Standard cell culture conditions are selenium deficient and hyperglycemic, which both inhibit SelS expression. Under conditions of limiting selenium, the cell prioritizes its use for the expression of essential selenoproteins, at the expense of non-essential selenoproteins, a phenomenon known as the selenoprotein hierarchy. For interpreting overexpression studies, it is often not clear that the 39UTR or an intact SECIS element was included in the construct, which is necessary for Sec insertion. In contrast, overexpression of SelS BU 4061T Proteasome inhibitor<\/a> appears robust by immunofluorescence and western blot and can reach levels that distort the architecture of the ER itself. The discrepancy between these observations could be explained by a mixed population of protein isoforms. Overexpression of a SelS construct that can produce a selenoprotein in cell culture would need to overcome the obstacles of a poor SECIS element, deficient selenium supply and competition for limiting SBP2 in order to be expressed in the selenoprotein form. Thus, it is likely a truncated SelS protein that does not contain Sec would be expressed under standard cell culture conditions.<\/p>\n","protected":false},"excerpt":{"rendered":"

In addition to its function as a putative SRE, the formation of SL1 has an additional consequence in primates. RNA structures are well known to ASP1517 influence mRNA splicing. The 59 splice site responsible for generating the SelS variant 1 mRNA is sequestered in the double-stranded stem of SL1, preventing the splicing event. Thus, factors … Continue reading “The penultimate Sec participates in an intramolecular the SL1 within SelS is the second functional SRE to be identified”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"_links":{"self":[{"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/posts\/1206"}],"collection":[{"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/comments?post=1206"}],"version-history":[{"count":1,"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/posts\/1206\/revisions"}],"predecessor-version":[{"id":1207,"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/posts\/1206\/revisions\/1207"}],"wp:attachment":[{"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/media?parent=1206"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/categories?post=1206"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/tags?post=1206"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}