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Nucleotide sequence of miRNA precursor contributes to cleavage site selection by Dicer.

ABSTRACT: The ribonuclease Dicer excises mature miRNAs from a diverse group of precursors (pre-miRNAs), most of which contain various secondary structure motifs in their hairpin stem. In this study, we analyzed Dicer cleavage in hairpin substrates deprived of such motifs. We searched for the factors other than the secondary structure, which may influence the length diversity and heterogeneity of miRNAs. We found that the nucleotide sequence at the Dicer cleavage site influences both of these miRNA characteristics. With regard to cleavage mechanism, we demonstrate that the Dicer RNase IIIA domain that cleaves within the 3' arm of the pre-miRNA is more sensitive to the nucleotide sequence of its substrate than is the RNase IIIB domain. The RNase IIIA domain avoids releasing miRNAs with G nucleotide and prefers to generate miRNAs with a U nucleotide at the 5' end. We also propose that the sequence restrictions at the Dicer cleavage site might be the factor that contributes to the generation of miRNA duplexes with 3' overhangs of atypical lengths. This finding implies that the two RNase III domains forming the single processing center of Dicer may exhibit some degree of flexibility, which allows for the formation of these non-standard 3' overhangs.

SUBMITTER: Starega-Roslan J

PROVIDER: S-EPMC4678860 | biostudies-other | 2015 Dec

REPOSITORIES: biostudies-other

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Nucleotide sequence of miRNA precursor contributes to cleavage site selection by Dicer.

Starega-Roslan Julia J Galka-Marciniak Paulina P Krzyzosiak Wlodzimierz J WJ

Nucleic acids research 20150930 22

The ribonuclease Dicer excises mature miRNAs from a diverse group of precursors (pre-miRNAs), most of which contain various secondary structure motifs in their hairpin stem. In this study, we analyzed Dicer cleavage in hairpin substrates deprived of such motifs. We searched for the factors other than the secondary structure, which may influence the length diversity and heterogeneity of miRNAs. We found that the nucleotide sequence at the Dicer cleavage site influences both of these miRNA charact ...[more]

PMID: 26424848

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Project description:Mutations in amyloid ? precursor protein (APP) gene alter APP processing, either causing familial Alzheimer's disease (AD) or protecting against dementia. Under normal conditions, ?-site APP cleaving enzyme 1 (BACE1) cleaves APP at minor Asp1 site to generate C99 for amyloid ? protein (A?) production, and predominantly at major Glu11 site to generate C89, resulting in truncated A? production. We discovered that A673V mutation, the only recessive AD-associated APP mutation, shifted the preferential ?-cleavage site of BACE1 in APP from the Glu11 site to the Asp1 site both in male and female transgenic mice in vivo and in cell lines and primary neuronal culture derived from timed pregnant rats in vitro, resulting in a much higher C99 level and C99/C89 ratio. All other mutations at this site, including the protective Icelandic A673T mutation, reduced C99 generation, and decreased the C99/C89 ratio. Furthermore, A673V mutation caused stronger dimerization between mutant and wild-type APP, enhanced the lysosomal degradation of the mutant APP, and inhibited ?-secretase cleavage of the mutant C99 to generate A?, leading to recessively inherited AD. The results demonstrate that APP673 regulates APP processing and the BACE1 cleavage site selection is critical for amyloidogenesis in AD pathogenesis, and implicate a pharmaceutical potential for targeting the APP673 site for AD drug development.SIGNIFICANCE STATEMENT ?-site APP cleaving enzyme 1 (BACE1) is essential for amyloid ? protein production. We discovered that A673V mutation shifted the BACE1 cleavage site from the Glu11 to the Asp1 site, resulting in much higher C99 level and C99/C89 ratio. All other mutations at this site of amyloid ? precursor protein (APP) reduced C99 generation and decreased the C99/C89 ratio. Furthermore, A673V mutation resulted in stronger dimerization between mutant and wild-type APP, enhanced the lysosomal degradation of the mutant APP, and inhibited ?-secretase cleavage of the mutant C99 to generate amyloid ? protein, leading to recessively inherited Alzheimer's disease (AD). The results demonstrate that APP673 regulates APP processing, and the BACE1 cleavage site selection is critical for amyloidogenesis in AD pathogenesis, and implicate a pharmaceutical potential for targeting the APP673 site for AD drug development.

Dataset Information

Nucleotide sequence of miRNA precursor contributes to cleavage site selection by Dicer.

Publications

Nucleotide sequence of miRNA precursor contributes to cleavage site selection by Dicer.

Similar Datasets

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