Decoding Biomechanical Cues Based on DNA Sensors.

Biological systems perceive and respond to mechanical forces, generating mechanical cues to regulate life processes. Analyzing biomechanical forces has profound significance for understanding biological functions. Therefore, a series of molecular mechanical techniques have been developed, mainly including single-molecule force spectroscopy, traction force microscopy, and molecular tension sensor systems, which provide indispensable tools for advancing the field of mechanobiology. DNA molecules with a programmable structure and well-defined mechanical characteristics have attached much attention to molecular tension sensors as sensing elements, and are designed for the study of biomechanical forces to present biomechanical information with high sensitivity and resolution. In this work, a comprehensive overview of molecular mechanical technology is presented, with a particular focus on molecular tension sensor systems, specifically those based on DNA. Finally, the future development and challenges of DNA-based molecular tension sensor systems are looked upon.

Gradient-independent Wnt signaling instructs asymmetric neurite pruning in C. elegans.

During development, the nervous system undergoes a refinement process by which neurons initially extend an excess number of neurites, the majority of which will be eliminated by the mechanism called neurite pruning. Some neurites undergo stereotyped and developmentally regulated pruning. However, the signaling cues that instruct stereotyped neurite pruning are yet to be fully elucidated. Here we show that Wnt morphogen instructs stereotyped neurite pruning for proper neurite projection patterning of the cholinergic motor neuron called PDB in C. elegans. In lin-44/wnt and lin-17/frizzled mutant animals, the PDB neurites often failed to prune and grew towards the lin-44-expressing cells. Surprisingly, membrane-tethered lin-44 is sufficient to induce proper neurite pruning in PDB, suggesting that neurite pruning does not require a Wnt gradient. LIN-17 and DSH-1/Dishevelled proteins were recruited to the pruning neurites in lin-44-dependent manners. Our results revealed the novel gradient-independent role of Wnt signaling in instructing neurite pruning.