Research

In Ghalei lab, we combine an array of in vivo and in vitro techniques to understand the assembly and turnover of box C/D snoRNPs involved in RNA-guided site-specific methylation of their targets. Ribose 2’-O-methylation is one of the most abundant modifications found in all major classes of RNA (mRNAs, tRNAs, rRNAs, snRNAs and lnRNAs). The modification sites are often located in the most conserved and functionally important regions of the RNA. The vast majority of these modifications are introduced by box C/D snoRNPs using an RNA-guided mechanism.

Beyond their role in ribose methylation, box C/D snoRNAs are also involved in processing and acetylation of rRNAs. Furthermore, they have been implicated in regulation of mRNAs during metabolic stress, alternative splicing and control of tumor cell fate by acting as oncogenes or tumor suppressors. Thus, dysregulation of box C/D snoRNPs leads to perturbation of serval cellular processes and is associated with an increased risk for many cancers, but the molecular bases behind these links are not understood.

Interestingly, snoRNAs are found to be differentially expressed between different cell types, in normal and malignant cells, and under different stress conditions, suggesting that they might have different turnover rates that could affect the function of their targets under cellular stress. In line with this, recent advancements in sequencing technologies and mapping of 2’-O-methylation sites have enabled detection of differential ribose methylation patterns in the ribosomal and spliceosomal RNAs in different cell populations, implying the combinatorial potential of modified RNA residues in regulating or fine-tuning ribosomes or spliceosomes. It remains to be cleared whether and how the spliceosome and ribosome heterogeneity affects cellular transcriptome and proteome.

Despite their importance, eukaryotic box C/D snoRNPs and their precursors have so far escaped in depth structural and biochemical characterization. Moreover, little is known about regulation of snoRNA turnover and quality control mechanisms that recognize and degrade aberrant snoRNP complexes. In the Ghalei lab, we aim at: 1) dissecting the assembly pathway of eukaryotic box C/D snoRNPs at a molecular level, 2) understanding how dysregulation of box C/D snoRNP biogenesis and function affect the cell and 3) unveiling how the defective box C/D snoRNPs are degraded.

Our findings will not only answer fundamental novel biological questions but also provide new avenues for the design of therapeutic agents that facilitate the selective manipulation of ribosome and spliceosome biogenesis in malignant cells.