A Unique Stem-Loop Structure In The 3'-Untranslated Region Of The Human Surfactant Protein-B (SP-B) MRNA Binds A 115 KDa Protein And Is Sufficient For Regulation Of MRNA Stability

Author(s):  
Joseph L. Alcorn ◽  
David E. Payne ◽  
Weizhen Bi ◽  
Su Pan
2012 ◽  
Vol 302 (10) ◽  
pp. L1107-L1117 ◽  
Author(s):  
Helen W. Huang ◽  
David E. Payne ◽  
Weizhen Bi ◽  
Su Pan ◽  
Shirley R. Bruce ◽  
...  

The ability of pulmonary surfactant to reduce alveolar surface tension requires adequate expression of surfactant protein B (SP-B). Dexamethasone (DEX, 10−7 M) increases human SP-B mRNA stability by a mechanism that requires a 126-nt-long segment (the 7.6S region) of the 3′-untranslated region (3′-UTR). The objective of this study was to identify sequences in the 7.6S region that mediate regulation of SP-B mRNA stability. The 7.6S region was found to be sufficient for DEX-mediated stabilization of mRNA. Sequential substitution mutagenesis of the 7.6S region indicates that a 90-nt region is required for DEX-mediated stabilization and maintenance of intrinsic stability. In this region, one 30-nt-long element (002), predicted to form a stem-loop structure, is sufficient for DEX-mediated stabilization of mRNA and intrinsic mRNA stability. Cytosolic proteins specifically bind element 002, and binding activity is unaffected whether proteins are isolated from cells incubated in the absence or presence of DEX. While loop sequences of element 002 have no role in regulation of SP-B mRNA stability, the proximal stem sequences are required for DEX-mediated stabilization and specific binding of proteins. Mutation of the sequences that comprise the proximal or distal arm of the stem negates the destabilizing activity of element 002 on intrinsic SP-B mRNA stability. These results indicate that cytosolic proteins bind a single hairpin structure that mediates intrinsic and hormonal regulation of SP-B mRNA stability via mechanisms that involve sequences of the stems of the hairpin structure.


2018 ◽  
Vol 87 (2) ◽  
Author(s):  
John T. Loh ◽  
Aung Soe Lin ◽  
Amber C. Beckett ◽  
Mark S. McClain ◽  
Timothy L. Cover

ABSTRACTHelicobacter pyloriCagA is a secreted effector protein that contributes to gastric carcinogenesis. Previous studies showed that there is variation amongH. pyloristrains in the steady-state levels of CagA and that a strain-specific motif downstream of thecagAtranscriptional start site (the +59 motif) is associated with both high levels of CagA and premalignant gastric histology. ThecagA5′ untranslated region contains a predicted stem-loop-forming structure adjacent to the +59 motif. In the current study, we investigated the effect of the +59 motif and the adjacent stem-loop oncagAtranscript levels andcagAmRNA stability. Using site-directed mutagenesis, we found that mutations predicted to disrupt the stem-loop structure resulted in decreased steady-state levels of both thecagAtranscript and the CagA protein. Additionally, these mutations resulted in a decreasedcagAmRNA half-life. Mutagenesis of the +59 motif without altering the stem-loop structure resulted in reduced steady-statecagAtranscript and CagA protein levels but did not affectcagAtranscript stability.cagAtranscript stability was not affected by increased sodium chloride concentrations, an environmental factor known to augmentcagAtranscript levels and CagA protein levels. These results indicate that both a predicted stem-loop structure and a strain-specific +59 motif in thecagA5′ untranslated region influence the levels ofcagAexpression.


2010 ◽  
Vol 30 (15) ◽  
pp. 3875-3886 ◽  
Author(s):  
Na Chang ◽  
Jie Yi ◽  
Gaier Guo ◽  
Xinwen Liu ◽  
Yongfeng Shang ◽  
...  

ABSTRACT In this study, we show that HuR destabilizes p16INK4 mRNA. Although the knockdown of HuR or AUF1 increased p16 expression, concomitant AUF1 and HuR knockdown had a much weaker effect. The knockdown of Ago2, a component of the RNA-induced silencing complex (RISC), stabilized p16 mRNA. The knockdown of HuR diminished the association of the p16 3′ untranslated region (3′UTR) with AUF1 and vice versa. While the knockdown of HuR or AUF1 reduced the association of Ago2 with the p16 3′UTR, Ago2 knockdown had no influence on HuR or AUF1 binding to the p16 3′UTR. The use of EGFP-p16 chimeric reporter transcripts revealed that p16 mRNA decay depended on a stem-loop structure present in the p16 3′UTR, as HuR and AUF1 destabilized EGFP-derived chimeric transcripts bearing wild-type sequences but not transcripts with mutations in the stem-loop structure. In senescent and HuR-silenced IDH4 human diploid fibroblasts, the EGFP-p16 3′UTR transcript was more stable. Our results suggest that HuR destabilizes p16 mRNA by recruiting the RISC, an effect that depends on the secondary structure of the p16 3′UTR and requires AUF1 as a cofactor.


1987 ◽  
Vol 7 (12) ◽  
pp. 4557-4559
Author(s):  
N B Pandey ◽  
W F Marzluff

Chimeric genes were made by fusing mouse histone genes with a human alpha-globin gene. The genes were introduced into mouse L cells and the stability of the chimeric mRNAs was measured when DNA synthesis was inhibited. An mRNA containing all the globin coding sequences and the last 30 nucleotides of the histone mRNA was degraded at the same rate as histone mRNA.


Development ◽  
1995 ◽  
Vol 121 (11) ◽  
pp. 3809-3818 ◽  
Author(s):  
T.L. Serano ◽  
R.S. Cohen

The establishment of dorsoventral polarity in the Drosophila oocyte and future embryo is dependent on the efficient transport of K10 mRNA from nurse cells into the oocyte. To investigate the cis-requirements of K10 mRNA transport, we used a transgenic fly assay to analyze the expression patterns of a series of K10 deletion variants. Such studies identify a 44 nucleotide sequence within the K10 3′ untranslated region that is required and sufficient for K10 mRNA transport and subsequent localization to the oocyte's anterior cortex. An inspection of the 44 nucleotide transport/localization sequence (TLS) reveals a strong potential for the formation of a stem-loop secondary structure. Nucleotide substitutions that interfere with the predicted base-pairing of the TLS block mRNA transport and anterior localization. Conversely, mutations that alter the base composition of the TLS while maintaining predicted base-pairing do not block mRNA transport or anterior localization. We conclude that K10 mRNA transport and anterior localization is mediated by a 44 nucleotide stem-loop structure. A similar putative stem-loop structure is found in the 3′ untranslated region of the Drosophila orb mRNA, suggesting that the same factors mediate the transport and anterior localization of both K10 and orb mRNAs. Apart from orb, the K10 TLS is not found in any other localized mRNA, raising the possibility that the transport and localization of other mRNAs, e.g., bicoid, oskar and gurken, are mediated by novel sets of cis- and trans-acting factors. Moreover, we find that the K10 TLS overrides the activity of oskar cis-regulatory elements that mediate the late stage movement of the mRNA to the posterior pole. We propose the existence of a family of cis-regulatory elements that mediate mRNA transport into the oocyte, only some of which are compatible with the elements that mediate late stage movements.


2003 ◽  
Vol 77 (20) ◽  
pp. 11284-11289 ◽  
Author(s):  
A. Corina Vlot ◽  
John F. Bol

ABSTRACT The three genomic RNAs of alfalfa mosaic virus each contain a unique 5′ untranslated region (5′ UTR). Replacement of the 5′ UTR of RNA 1 by that of RNA 2 or 3 yielded infectious replicons. The sequence of a putative 5′ stem-loop structure in RNA 1 was found to be required for negative-strand RNA synthesis. A similar putative 5′ stem-loop structure is present in RNA 2 but not in RNA 3.


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