Ultra-low-input rG4-seq reveals the RNA G-quadruplex regulome in gene expression and genome integrity.

RNA G-quadruplexes (rG4s), formed through guanine self-recognition into stacked tetrads, serve as critical regulators of gene expression, yet their comprehensive mapping and dynamic regulation in physiological contexts remain technically challenging. Here, we develop Ultra-low-input rG4-seq (ULI-rG4-seq), enabling precise rG4 detection enabling precise rG4 detection with ∼140 bp resolution in samples as small as 100 oocytes, and reveal notable enrichment of rG4s near crucial regulatory regions, particularly transcription start sites and end sites. This technological advance, combined with Trim-away or oocyte-specific knockout of DHX36 (also known as G4R1 or RHAU), an rG4-specific helicase, reveals acute and chronic loss of DHX36 leads to opposing effects on rG4 levels. This observation extends beyond the traditional view of helicases as unwinding enzymes and suggests sophisticated cellular mechanisms maintaining RNA structural homeostasis. Through integrated analysis of rG4 landscapes and DHX36-binding profiles, we demonstrate coordination between cytoplasmic rG4 regulation and nuclear gene expression, revealing how RNA structure dynamics orchestrate RNA stability and translation, thereby influencing transcriptional elongation, genome stability, and alternative splicing. Finally, we show that deletion of DHX36 resulted in decreased oocyte quality, premature ovarian failure and complete female infertility due to transcriptional defects and genome instability related to R-loop accumulation. These technological and conceptual advances not only deepen our understanding of RNA-based regulation but also open new therapeutic possibilities for diseases involving RNA structure.