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Updated: Nov 17, 2025

A Reporter Assay to Analyze Intronic microRNA Maturation in Mammalian Cells
Published on: June 16, 2022
DGCR8-dependent efficient pri-miRNA processing of human pri-miR-9-2
Masahiro Nogami1, Kazumasa Miyamoto2, Yoshika Hayakawa-Yano3
1Innovative Biology Laboratories, Neuroscience Drug Discovery Unit, Research, Takeda Pharmaceutical Company Limited, Fujisawa, Kanagawa, Japan; Shonan Incubation Laboratories, Takeda Pharmaceutical Company Limited, Fujisawa, Kanagawa, Japan.
Abstract:
Microprocessor complex, including DiGeorge syndrome critical region gene 8 (DGCR8) and DROSHA, recognizes and cleaves primary transcripts of microRNAs (pri-miRNAs) in the maturation of canonical miRNAs. The study of DGCR8 haploinsufficiency reveals that the efficiency of this activity varies for different miRNA species. It is thought that this variation might be associated with the risk of schizophrenia with 22q11 deletion syndrome caused by disruption of the DGCR8 gene. However, the underlying mechanism for varying action of DGCR8 with each miRNA remains largely unknown. Here, we used in vivo monitoring to measure the efficiency of DGCR8-dependent microprocessor activity in cultured cells. We confirmed that this system recapitulates the microprocessor activity of endogenous pri-miRNA with expression of a ratiometric fluorescence reporter. Using this system, we detected mir-9-2 as one of the most efficient targets. We also identified a novel DGCR8-responsive RNA element, which is highly conserved among mammalian species and could be regulated at the epi-transcriptome (RNA modification) level. This unique feature between DGCR8 and pri-miR-9-2 processing may suggest a link to the risk of schizophrenia.
Insights
DiGeorge syndrome critical region gene 8 (DGCR8) efficiency varies for different microRNAs (miRNAs), potentially linking DGCR8 disruption to schizophrenia risk. A novel DGCR8-responsive element in pri-miR-9-2 may be key.
Area of Science:
- Molecular Biology
- Genetics
- Neuroscience
Background:
- The microprocessor complex, containing DGCR8 and DROSHA, processes primary microRNAs (pri-miRNAs) for canonical miRNA maturation.
- DGCR8 haploinsufficiency shows variable efficiency across miRNA species, implicated in schizophrenia risk associated with 22q11 deletion syndrome.
- The precise mechanisms behind DGCR8's differential activity on various miRNAs are not fully understood.
Purpose of the Study:
- To investigate the varying efficiency of DGCR8-dependent microprocessor activity on different pri-miRNAs.
- To identify specific miRNA targets and regulatory elements involved in DGCR8 processing.
- To explore potential links between DGCR8-miRNA interactions and schizophrenia risk.
Main Methods:
- Utilized an in vivo monitoring system with ratiometric fluorescence reporters to measure DGCR8-dependent microprocessor activity in cultured cells.
- Validated the system's ability to recapitulate endogenous pri-miRNA processing.
- Analyzed DGCR8-responsive RNA elements and their conservation across species.
Main Results:
- Confirmed DGCR8-dependent microprocessor activity using the developed reporter system.
- Identified microRNA-9-2 (mir-9-2) as a highly efficient DGCR8 target.
- Discovered a novel, conserved DGCR8-responsive RNA element potentially regulated at the epitranscriptome level.
Conclusions:
- The study provides a system to measure DGCR8 activity and reveals differential processing of pri-miRNAs.
- Pri-miR-9-2 processing by DGCR8, influenced by a novel RNA element, may contribute to schizophrenia risk in 22q11 deletion syndrome.
- Further research into DGCR8-miRNA interactions and epitranscriptomic regulation is warranted.
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