Spaceflight-Associated miRNAs Alters Expression of Targeted Genes in Ocular and Spinal Tissue Under Simulated Spaceflight Conditions

Abstract

Purpose : Spaceflight exposes humans to stress of microgravity and radiation, leading to immunosuppression, muscle atrophy, cardiovascular damage, and visual disturbances. Minimizing or mitigating these pathological changes is necessary for future deep space missions. Several spaceflight-related pathologies are associated with the altered expression of 13 miRNAs. Previously, we found increased expression of these spaceflight-associated miRNAs in rodents exposed to either simulated or real spaceflight and partial conservation in the space-flown twin of the NASA Twins Study. Moreover, small molecule inhibitors (antagomirs-Ag) targeting 3 spaceflight-associated miRNAs reduced vascular inflammation in human tissue exposed to simulated spaceflight. Here, we examined the effects of inhibiting these 3 spaceflight-associated miRNAs in mice before exposure to simulated spaceflight conditions.

Methods : We used 6 groups of 20 female mice: control, control + Ag, simulated gamma-cosmic rays (GCRs), GCRs + Ag, simulated space particle event (SPE), and SPE + Ag. Half of each group was housed with hindlimb unloading to simulate microgravity. Ag-treated mice were treated every 3 days, with the last treatment 24 hours before irradiation. We harvested the vertebral column and eyes. We isolated total RNA and used RT-qPCR to measure expression levels of 13 candidate genes.

Results : We identified 13 gene targets of 3 miRNAs via mirNET, mirWalk, and Cluepedia databases (Figure). Differences in relative expression of 13 genes was analyzed via Welch’s unpaired t-test and two-way ANOVA. We found changes in spinal cord expression of 9 genes when treated with spaceflight-associated miRNA Ag (p < 0.05), several of which are involved in mitotic function, membrane organization, and phosphatase regulation. Conversely, in eyes we found that Ag treatment only changed expression of one gene (Zcchc9; sham vs SPE + Ag, p< 0.05; sham vs Sham + Ag p< 0.05), that encodes a zinc-finger containing protein phosphatase. However, simulated-spaceflight radiation and microgravity alone did not influence expression of the 13 target genes in the eye or spinal cord.

Conclusions : Our study demonstrates that inhibition of miRNAs in preclinical models of simulated spaceflight has potential for preventing biological damage.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

Spaceflight-Associated miRNAs Alters Expression of Targeted Genes in Ocular and Spinal Tissue