Project description:In humans, DICER is a key regulator of gene expression through its production of miRNAs and siRNAs by processing miRNA precursors (pre-miRNAs), short-hairpin RNAs (shRNAs), and long double-stranded RNAs (dsRNAs). To advance our understanding of this process, we employed high-throughput dicing assays using various shRNA variants and both wild-type and mutant DICER. Our analysis revealed that DICER predominantly cleaves shRNAs at two positions, specifically at 21 (DC21) and 22 (DC22) nucleotides from their 5'-end. Our investigation identified two different motifs, mWCU and YCR, that determine whether DICER cleaves at DC21 or DC22, depending on their locations in shRNAs/pre-miRNAs. These motifs can work together or independently to determine the cleavage sites of DICER. Furthermore, our findings indicate that dsRNA-binding domain (dsRBD) of DICER enhances its cleavage, and mWCU strengthens the interaction between dsRBD and RNA, leading to an even greater enhancement of the cleavage. Conversely, YCR functions independently of dsRBD. Our study proposes a two-motif model that sheds light on the intricate regulatory mechanisms involved in gene expression by elucidating how DICER recognizes its substrates, providing valuable insights into this critical biological process.
Project description:DICER is a key regulator of gene expression in animals through its production of miRNAs and siRNAs by processing shRNA. To advance our understanding of this process, we employed high-throughput assays using various shRNA variants and both wild-type and mutant DICER (DICERΔdsRBD). Our analysis revealed that DICER predominantly cleaves shRNAs at two positions, specifically at 21 (DC21) and 22 (DC22) nucleotides from the 5'-end. Our investigation identified two independent motifs, mAHG and YSR, that determine whether DICER cleaves at DC21 or DC22, depending on their location in shRNA/pre-miRNAs. These motifs can work together or independently to determine the cleavage sites of DICER. Furthermore, our findings indicate that dsRBD enhances cleavage at DC21, and mAHG strengthens the interaction between dsRBD and RNA, leading to an even greater enhancement of DC21 cleavage. Conversely, YSR functions independently of dsRBD. Our study proposes a two-motif model that sheds light on the intricate regulatory mechanisms involved in gene expression by elucidating how DICER recognizes its substrate, providing valuable insights into this critical biological process.
Project description:In humans, DICER is a key regulator of gene expression in animals through its production of miRNAs and siRNAs by processing miRNA precursors (pre-miRNAs), short-hairpin RNAs (shRNAs), and long double-stranded RNAs (dsRNAs). To advance our understanding of this process, we employed high-throughput assays using various shRNA variants and both wild-type and mutant DICER (DICERΔdsRBD). Our analysis revealed that DICER predominantly cleaves shRNAs at two positions, specifically at 21 (DC21) and 22 (DC22) nucleotides from the 5'-end. Our investigation identified two independent motifs, mWCU and YCR, that determine whether DICER cleaves at DC21 or DC22, depending on their locations in shRNA/pre-miRNAs. These motifs can work together or independently to determine the cleavage sites of DICER. Furthermore, our findings indicate that dsRBD enhances cleavage at DC21, and mWCU strengthens the interaction between dsRBD and RNA, leading to an even greater enhancement of DC21 cleavage. Conversely, YCR functions independently of dsRBD. Our study proposes a two-motif model that sheds light on the intricate regulatory mechanisms involved in gene expression by elucidating how DICER recognizes its substrate, providing valuable insights into this critical biological process.
Project description:In humans, DICER is a key regulator of gene expression in animals through its production of miRNAs and siRNAs by processing miRNA precursors (pre-miRNAs), short-hairpin RNAs (shRNAs), and long double-stranded RNAs (dsRNAs). To advance our understanding of this process, we employed high-throughput assays using various shRNA variants and both wild-type and mutant DICER (DICERΔdsRBD). Our analysis revealed that DICER predominantly cleaves shRNAs at two positions, specifically at 21 (DC21) and 22 (DC22) nucleotides from the 5'-end. Our investigation identified two independent motifs, mWCU and YCR, that determine whether DICER cleaves at DC21 or DC22, depending on their locations in shRNA/pre-miRNAs. These motifs can work together or independently to determine the cleavage sites of DICER. Furthermore, our findings indicate that dsRBD enhances cleavage at DC21, and mWCU strengthens the interaction between dsRBD and RNA, leading to an even greater enhancement of DC21 cleavage. Conversely, YCR functions independently of dsRBD. Our study proposes a two-motif model that sheds light on the intricate regulatory mechanisms involved in gene expression by elucidating how DICER recognizes its substrate, providing valuable insights into this critical biological process.
Project description:Dicer proteins are known to produce small RNAs (sRNAs) from long double-stranded RNA (dsRNA) templates. These sRNAs are bound by Argonaute proteins, which select the guide strand, often with a 5' end sequence bias. However, Dicer proteins have never been shown to have sequence cleavage preferences. In Paramecium development, two classes of sRNAs that are required for DNA elimination are produced by three Dicer-like enzymes: Dcl2, Dcl3, and Dcl5. Through in vitro cleavage assays, we demonstrate that Dcl2 has a strict size preference for 25 nt and a sequence preference for 5' U and 5' AGA, while Dcl3 has a sequence preference for 5' UNG. Dcl5, however, has cleavage preferences for 5' UAG and 3' CUAC/UN, which leads to the production of RNAs precisely matching short excised DNA elements with corresponding end base preferences. Thus, we characterize three Dicer-like enzymes that are involved in Paramecium development and propose a biological role for their sequence-biased cleavage products.