Recent discoveries have revealed the existence of glycosylated RNAs (glycoRNA), in which glycans are covalently linked to small non‑coding RNAs and are predominantly localized to the cell surface. Since the initial discovery in 2021, glycoRNA has become an emerging field: 4 years in glycoRNA research have produced advances in labeling, imaging, and mass spectrometry that now highlight the role of glycoRNA in cell communication, immune regulation, and disease progression. In this review, we summarize current knowledge of glycoRNA biogenesis, detection techniques, and biological functions, and discuss how these findings reshape the future interface between glycobiology and RNA biology.

Cell surface RNAs, notably glycoRNAs, have been reported, yet the precise compositions of surface RNAs across different primary cell types remain unclear. Here, we introduce a comprehensive suite of methodologies for profiling, imaging, and quantifying specific surface RNAs. We present AMOUR, a method leveraging T7-based linear amplification, to profile surface RNAs while preserving plasma membrane integrity. By integrating fluorescently labeled DNA probes with live primary cells, and employing imaging along with flow cytometry analysis, we can effectively image and quantify representative surface RNAs. Utilizing these techniques, we have identified diverse non-coding RNAs present on mammalian cell surfaces, expanding beyond the known glycoRNAs. We confirm the membrane anchorage and quantify the abundance of several representative surface RNA molecules in cultured HeLa cells and human umbilical cord blood mononuclear cells (hUCB-MNCs). Our imaging and flow cytometry analyses unequivocally confirm the membrane localization of Y family RNAs, spliceosomal snRNA U5, mitochondrial rRNA MTRNR2, mitochondrial tRNA MT-TA, VTRNA1-1, and the long non-coding RNA XIST. Our study not only introduces effective approaches for investigating surface RNAs but also provides a detailed portrayal of the surface RNA landscapes of hUCB-MNCs and murine blood cells, paving the way for future research in the field of surface RNAs.

Mouse extended pluripotent stem (EPS) cells have demonstrated significant potential for generating embryo models in vitro. However, their limited capacity for extraembryonic trophoblast development has hindered their use in constructing whole embryo models, particularly post-implantation embryoids. Here, we establish a stepwise induction protocol to generate trophectoderm-like cells from mouse EPS cells. These cells retain trophectoderm-specific transcriptomic features and can differentiate into trophoblast lineages in vivo. Moreover, combining these trophectoderm-like cells with EPS cell-derived primitive endoderm/epiblast bilineage structures enabled the robust generation of post-implantation embryoids in a transgene-free manner. EPS-derived embryoids recapitulate key developmental events of post-implantation mouse embryos, including the formation of the pro-amniotic cavity, anterior-posterior axis, primitive streak, gastrulation, and complex extraembryonic tissues. Notably, single-cell transcriptomic analysis revealed a high degree of transcriptional similarity between EPS-derived embryoids at day 6 and natural E7.5 mouse embryos. Our study presents a novel platform for modeling post-implantation mouse embryogenesis in vitro.

Breast cancer is a prevalent malignancy worldwide. The majority of breast cancers belong to the estrogen receptor (ER)-positive luminal subtype that can be effectively treated with antiestrogen therapies. However, a significant portion of such malignancies become hormone-refractory and incurable. Cancer cells often uptake more cystines to increase glutathione (GSH) biosynthesis and reduce reactive oxygen species (ROS), thereby preventing ROS-induced ferroptosis and leading to therapeutic resistance. However, few molecules of these processes are targetable for cancer therapy. However, few therapeutic targets have been established that target these processes. Here, we report that the gene for SLC7A13, a member of the SLC7A13-SLC3A1 cystine transporter, was amplified and overexpressed in 19.7% and 49.7% of breast cancers, respectively. SLC7A13 amplification and overexpression were associated with worse overall survival and disease-free survival in patients with luminal breast cancer. Functionally, SLC7A13 overexpression promoted, while its silencing attenuated, cell survival or proliferation. Molecularly, SLC7A13 silencing reduced cystine uptake and GSH biosynthesis, leading to increased lipid ROS levels. The cryo-EM structure of the human SLC7A13-SLC3A1 complex was determined at 2.64 Å, revealing a dimer-of-heterodimers architecture similar to that of other SLC3A1-linked transporters. A specific substrate-binding pocket was identified, containing distinct residues, which suggests a regulatory role in the cystine transporter. These findings suggest that the SLC7A13-SLC3A1 cystine transporter is a therapeutic target for treating luminal breast cancer. They also provide the structural insights for therapeutic development targeting the cystine transporter.