Introduction: Small nucleolar RNA (snoRNA) mediates RNA modifications, including 2′-O-methylation (Nm) and pseudouridine (Ψ), which has been proven to impact tumor progression. However, the role of snoRNA in the epigenetics of tumors remains poorly understood due to the lack of sufficiently effective experimental methods to identify snoRNA targets. Here, we identified SNORD13H, a C/D box snoRNA, as being downregulated in hepatocellular carcinoma (HCC), and its low expression was associated with HCC development.Methods: To elucidate specific roles of SNORD13H in HCC, we used a comprehensive array of methodologies, including flow cytometry, xenograft mouse model, reverse transcription at low dNTP concentration followed by PCR (RTL-P) assay, and surface sensing of translation (SUnSET) assay.Results: In this study, we first demonstrated that reduced SNORD13H serves as a biomarker for HCC, facilitating cellular proliferation. SNORD13H mediates 2′-O-methylations of 18S rRNA and RAS mRNA, thereby enhancing translation efficiency and regulating RAS protein levels in HCC. The diminution of SNORD13H activates the RAS pathway, contributing to the progression of HCC.Discussion: Our study establishes SNORD13H as a dual-function regulator in HCC progression. Furthermore, our findings indicate that SNORD13H is detectable in plasma, highlighting its potential utility in tumor screening.
Tissue homeostasis and regeneration involve complex cellular changes. The role of rRNA modification-dependent translational regulation in these processes remains largely unknown. Planarians, renowned for their ability to undergo remarkable tissue regeneration, provide an ideal model for the analysis of differential rRNA regulation in diverse cell types during tissue homeostasis and regeneration. We investigated the role of RNA 2’-O-methyltransferase, Fibrillarin (FBL), in the planarian Schmidtea mediterranea and identified two FBL homologs: Smed-fbl-1 (fbl-1) and Smed-fbl-2 (fbl-2). Both are essential for planarian regeneration, but play distinct roles: fbl-1 is crucial for progenitor cell differentiation, while fbl-2 is important for late-stage epidermal lineage specification. Different 2’-O-methylation patterns were observed upon fbl-1 and fbl-2 knockdown, suggesting their roles in translation of specific mRNA pools during regeneration. Ribo-seq analysis further revealed differing impacts of fbl-1 and fbl-2 knockdown on gene translation. These findings indicate divergent roles of the duplicate fbl genes in specific cell lineage development in planarians and suggest a role of rRNA modifications in translational regulation during tissue maintenance and regeneration.
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