In the era of space exploration, the microgravity environment has had a profound impact on the mechanical perception system of cells. When the gravitational acceleration drops to one millionth of the Earth's surface, the integrin receptors on the cell membrane first sense the absence of mechanical stimulation, and this primary signal is transmitted into the cell through the adhesive plaque complex. Research has found that stress fibers in the cytoskeleton undergo significant depolymerization within 24 hours, and the arrangement direction of actin fibers changes from a regular network structure to a disordered state.

The cascade reaction of the mechanosensitive signaling pathway unfolds as follows: the decrease in ROCK kinase activity leads to a decrease in myosin light chain phosphorylation levels, which weakens cell contractility; At the same time, the activity of the FAK Src signal axis is suppressed, and the efficiency of adhesive spot formation is reduced by more than 40%. More notably, the nuclear localization of the mechanical transduction core element YAP/TAZ was significantly reduced, resulting in a decrease of approximately 60% in the expression of proliferation related genes mediated by TEAD transcription factors.

At the level of metabolic signaling networks, abnormal activation of the AMPK pathway prompts cells to shift from oxidative phosphorylation to glycolysis for energy supply. Mitochondrial morphological analysis showed a 30% decrease in ridge structure density, accompanied by a decrease in ATP production. This energy crisis further exacerbates the inhibition of the ERK/MAPK pathway, leading to a 1.8-fold increase in the proportion of cell cycle arrest in the G1 phase.

Epigenetic regulation is also involved in this process: the activity of histone deacetylase HDAC3 increases, leading to a decrease in the acetylation modification level of histone H3K27 in the promoter region of mechanosensitive genes. Single cell transcriptome sequencing revealed significant changes in the expression profiles of 378 genes involved in cytoskeleton remodeling, with prominent disruptions in the Rho GTPase regulatory network.

These findings not only reveal the fundamental role of gravity in cellular signaling networks, but also provide a molecular blueprint for developing targeted intervention strategies to combat the physiological effects of the space environment. In the future, research on bioreactors that simulate microgravity effects is expected to open up new application pathways in the fields of tissue engineering and regenerative medicine.