Biology subjects

Abrahamsson, A.

Publications and source records attributed to Abrahamsson, A..

3 recordsLinked to original sources

bioRxiv2026

Dual Recognition Drives Site-Directed G-Quadruplex Stabilization: Exploring Oligonucleotide Design in G4 Ligand-Oligonucleotide Conjugates

G-quadruplex (G4) DNA structures are increasingly recognized for their roles in key cellular processes, including transcriptional regulation and genome stability, making them attractive therapeutic targets. Selective recognition of individual G4s remains challenging due to the high structural similarity among human G4 motifs. The G4 Ligand-conjugated Oligonucleotide strategy addresses this need by combining the G4-binding capabilities of small-molecule G4-ligands with the sequence specificity of an oligonucleotide complementary to the flanking region of the target G4. Here, we systematically explore how the oligonucleotide component governs G4 binding and stabilization by varying its length, backbone composition, and sequence complementarity. This revealed that efficient G4 recognition depends on a strong interdependence between hybridization and G4-ligand binding, such that both elements cooperatively reinforce complex stability and site specificity. Central mismatches disrupt this dual recognition and reduce selectivity. While longer oligonucleotides hybridize more slowly, they form more stable complexes and show stronger G4 stabilization in thermal melting and polymerase stop assays. Replacing the DNA oligonucleotide with peptide nucleic acid enhances binding strength, thermal stability, and metabolic stability, but selective G4 stabilization is achieved only upon ligand conjugation. Together, these results show how rational oligonucleotide design enables selective and potent recognition of G4 structures using GL-Os.

molecular biology↗

bioRxiv2023

G4-Ligand Conjugated Oligonucleotides Mediate Selective Binding and Stabilization of Individual G4 DNA Structures

G-quadruplex (G4) DNA structures are prevalent secondary DNA structures implicated in fundamental cellular functions such as replication and transcription. Furthermore, G4 structures are directly correlated to human diseases such as cancer and have been highlighted as promising therapeutic targets for their ability to regulate disease-causing genes, e.g., oncogenes. Small molecules that bind and stabilize these structures are thus valuable from a therapeutic perspective and helpful in studying the biological functions of G4 structures. However, there are hundreds of thousands of G4 DNA motifs in the human genome, and a longstanding problem in the field is how to achieve specificity amongst these different G4 structures. Here, we have developed a strategy to selectively target an individual G4 DNA structure. The strategy is based on a ligand that binds and stabilizes G4s without selectivity, conjugated to a guide oligonucleotide, that specifically directs the G4 Ligand conjugated Oligo (GL-O) to the single target G4 structure. By employing various biophysical and biochemical techniques, we show that the developed method enables the targeting of a unique, specific G4 structure without impacting other off-target G4 formations. Considering the vast amounts of G4s in the human genome, this represents a promising strategy to study the presence and functions of individual G4s but may also hold potential as a future therapeutic modality.

biochemistry↗

bioRxiv2023

Proteolytic Remodeling of 3D Bioprinted Tumor Microenvironments

In native tissue, remodeling of the pericellular space is essential for cellular activities and is mediated by tightly regulated proteases. Protease activity is dysregulated in many diseases, including many forms of cancer. Increased proteolytic activity is directly linked to tumor invasion into stroma, metastasis, and angiogenesis as well as all other hallmarks of cancer. Here we show how integrated 3D bioprinted structures with distinctly different responses to proteolytic activity can be utilized for systematic investigation of proteolytic remodeling of the extra cellular matrix and the impact of stromal cells on protease driven processes. Bioprinted structures combining non-degradable and degradable hydrogels were designed and demonstrated to be selectively degraded by proteases allowing for protease-mediated material reorganization with high spatial resolution. Bioprinting of tumor microenvironments combining bioinks with different susceptibilities to proteolytic degradation shows that breast cancer cell proliferation, migration into stromal compartments, and spheroid size are significantly increased in protease degradable hydrogels, but only in the presence of fibroblasts. Proteolytic remodeling of the tumor microenvironment has a significant effect on tumor progression and is drastically influenced by the intimate crosstalk between fibroblast and breast cancer cells.

bioengineering↗