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Spatial Separation of Molecular Conformers and Clusters
Published on: January 9, 2014
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Separable roles for Microprocessor and its cofactors, ERH and SAFB1/2, during microRNA cluster assistance
Renfu Shang1, Niko Popitsch2,3, Seungjae Lee1
1Developmental Biology Program, Sloan Kettering Institute, New York, New York 10065, USA.
Genes & Development
|January 22, 2026
Summary
Cluster assistance enhances microRNA (miRNA) biogenesis for suboptimal hairpins by transferring the Microprocessor complex. This study reveals the pathway for cofactors ERH and SAFB2 in this crucial miRNA processing regulation.
Area of Science:
- Molecular Biology
- RNA Biology
- Gene Regulation
Background:
- Most microRNA (miRNA) transcripts are efficiently processed into small RNAs.
- Some miRNA loci possess suboptimal features requiring additional regulatory layers, such as cluster assistance.
- Cluster assistance involves the Microprocessor complex (Drosha-DGCR8) and cofactors (ERH, SAFB1/2) facilitating suboptimal miRNA hairpin biogenesis.
Purpose of the Study:
- To elucidate the mechanisms underlying miRNA cluster assistance.
- To define features of suboptimal miRNAs dependent on cluster assistance.
- To delineate the roles of Microprocessor complex cofactors in this process.
Main Methods:
- Integration of mutant cells lacking Microprocessor components or cofactors.
- Analysis of miRNA structure-function variants.
- Biochemical assays and genome-wide profiling.
- Epistatic tests to order cofactor function.
Main Results:
- Identified critical interactions among Microprocessor components and cofactors for cluster assistance.
- Established a pathway for ERH (Microprocessor transfer) and SAFB factors (hairpin recognition/binding).
- Demonstrated cluster assistance integrates into a feedback loop regulating Microprocessor activity via DGCR8 transcript cleavage.
Conclusions:
- Uncovered complex regulatory transactions in clustered miRNA biogenesis.
- ERH facilitates Microprocessor complex transfer, while SAFB2 mediates stable binding to suboptimal miRNA hairpins.
- Cluster assistance represents a feedback mechanism influencing Microprocessor complex function.
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