Paraspeckle-Independent Co-Transcriptional Regulation of Nuclear microRNA Biogenesis by SFPQ [PRO-seq]

MicroRNAs (miRNAs) play crucial roles in physiological functions and diseases such as cancer, but the regulation of their nuclear biogenesis remains poorly understood. Here, BioID on Drosha, the catalytic subunit of the microprocessor complex, revealed its proximity to SFPQ, a multifunctional RNA-binding protein (RBP) notably involved in forming the paraspeckle nuclear condensates. SFPQ depletion impacted both primary and mature miRNA expression, while other crucial paraspeckle proteins or the paraspeckle scaffolding lncRNA NEAT1 did not, indicating a unique paraspeckle-independent role. Comprehensive transcriptomic analyses showed that SFPQ loss broadly affects RNA and miRNA host gene (miRNA HG) expression, influencing both their transcription and stability. Notably, SFPQ protects specific miRNA HGs, including the oncogenic miR-17~92 polycistron, from degradation by the nuclear NEXT-exosome complex. Lastly, we show that high SFPQ is tightly linked with overexpression miR-17~92 and its mature miRNAs across a broad variety of cancers. Our findings reveal a dual role for SFPQ in the regulation of miRNA HGs transcription and stability, as well as its significance in cancers. We used a multi-omic approach to uncover a dual role for SFPQ in the regulation of pri-miRNAs’ transcription and stability. We established an SBC-3 cell line in which SFPQ has been knocked down by siRNAs. We then performed nascent transcription profiling analysis using data obtained from PRO-seq at the 72h time point post-transfection.