Research

Little is known about the biological roles of glycosylated RNAs (glycoRNAs), a recently discovered class of glycosylated molecules, because of a lack of visualization methods. We report sialic acid aptamer and RNA in situ hybridization-mediated proximity ligation assay (ARPLA) to visualize glycoRNAs in single cells with high sensitivity and selectivity. The signal output of ARPLA occurs only when dual recognition of a glycan and an RNA triggers in situ ligation, followed by rolling circle amplification of a complementary DNA, which generates a fluorescent signal by binding fluorophore-labeled oligonucleotides. Using ARPLA, we detect spatial distributions of glycoRNAs on the cell surface and their colocalization with lipid rafts as well as the intracellular trafficking of glycoRNAs through SNARE protein-mediated secretory exocytosis. Studies in breast cell lines suggest that surface glycoRNA is inversely associated with tumor malignancy and metastasis. Investigation of the relationship between glycoRNAs and monocyte–endothelial cell interactions suggests that glycoRNAs may mediate cell–cell interactions during the immune response.

Despite the promise of combination cancer therapy, it remains challenging to develop targeted strategies that are nontoxic to normal cells. Here we report a combination therapeutic strategy based on engineered DNAzyme molecular machines that can promote cancer apoptosis via dynamic inter- and intracellular regulation. 

We reported a thiol-mediated uptake method that more efficiently delivers DNA into Arabidopsis and tobacco leaf cells than another state-of-the-art method, DNA nanostructures. Such a method allowed efficient delivery of a glucose DNA aptamer sensor into Arabidopsis for sensing glucose. This demonstration opens a new avenue to apply DNA aptamer sensors for functional studies of various targets, including metabolites, plant hormones, metal ions, and proteins in plants for a better understanding of the biodistribution and regulation of these species and their functions.

Detecting metal ions in vivo with a high spatiotemporal resolution is critical to understanding the roles of the metal ions in both healthy and disease states. We reported the use of high-intensity focused ultrasound (HIFU) to remotely deliver on-demand, spatiotemporally resolved thermal energy to activate the DNAzyme sensors at the targeted region both in vitro and in vivo. The current method can be applied to monitor many other metal ions for in vivo imaging and medical diagnosis using metal-specific DNAzymes that have either been obtained or can be selected using in vitro selection.

The misfolded proteins or polypeptides commonly observed in neurodegenerative diseases, including Alzheimer's disease (AD), are promising drug targets for developing therapeutic agents. To target the amyloid-β (Aβ) peptide plaques and oligomers, we have developed twelve amphiphilic small molecules with different hydrophobic and hydrophilic fragments. These amphiphilic compounds can label the Aβ species in the brain sections of transgenic AD mice.  ZY-15-MT and ZY-15-OMe, can disrupt the interactions between Aβ oligomers and cell membranes. Overall, these studies strongly suggest that developing compounds with amphiphilic properties that target Aβ oligomers and modulate the Aβ oligomer–cell membrane interactions can be an effective strategy for the development of small molecule AD therapeutics.

Lithium has been a drug for bipolar disorders (BD) for over 70 years; however, its usage has been limited by its narrow therapeutic window (between 0.6 and 1.2 mM). Understanding the cellular distribution of lithium ions (Li+) in patient cells will offer deep insight into this limitation, but selective imaging of Li+ in living cells under biomedically relevant concentration ranges has not been achieved. Herein, we report in vitro selection and development of a Li+-specific DNAzyme fluorescent sensor with >100-fold selectivity over other biorelevant metal ions. This sensor allows comparative Li+ visualization in HeLa cells, human neuronal progenitor cells (NPCs), and neurons derived from BD patients and healthy controls. Strikingly, we detected enhanced accumulation of Li+ in cells derived from BD patients compared with healthy controls in differentiated neurons but not NPCs. These results establish the DNAzyme-based sensor as a novel platform for biomedical research into BD and related areas using lithium drugs.

Regulating cell–cell interactions and cell behaviors via cell surface engineering is of significance for biological research. While extensive efforts have been made to induce cell–cell assembly, controllable cell–cell interactions that include both assembly and disassembly triggered by metal ions remain a challenge. Herein, we report a strategy based on DNAzymes to realize controllable cell–cell interactions, triggered by metal ions. The metal-dependent DNAzyme-based cleavage can effectively manipulate cell behaviors, including cell–cell conjunctions and disaggregation. Moreover, the method has been applied to control the assembly and disassembly between two cell spheroids. This method can be readily applied to construct cell dynamic systems controlled by other metal ions, providing a smart and versatile platform to regulate dynamic cell behavior.

The limited number of human hematopoietic stem cells (HSCs) has restrained their widespread clinical application. Despite great efforts in recent years, the in vitro expansion of HSCs remains a challenge due to incomplete understanding of the signaling networks underlying HSC self-renewal. Here, we show that culturing human cord blood (CB) CD34+ cells with JNK-IN-8, an inhibitor of the JNK signaling pathway, can enhance the self-renewal of HSCs with a 3.88-fold increase in cell number. These cultured CD34+ cells repopulated recipient mice for 21 weeks and can form secondary engraftment that lasted for more than 21 weeks. Knockdown of c-Jun, a major downstream target in the JNK pathway, promoted the expansion of hematopoietic stem and progenitor cells (HSPCs). Our findings demonstrate a critical role of the JNK pathway in regulating HSC expansion, provide new insights into HSC self-renewal mechanism, and may lead to improved clinical application of HSCs.