Direct observation of cytoskeleton-dependent trafficking of miRNA visualized by the introduction of pre-miRNA.

MicroRNA (miRNA) plays physiologically and pathologically important roles in post-transcriptional regulation. Although miRNA has been suggested to dynamically interact with cellular organelles, the dynamicity of intracellular miRNA behavior has remained unclear. Here, by introducing fluorescently labeled pre-miRNA into living cells, we improved the miRNA visualization method using exogenous miRNA precursors. Through the combination of our miRNA visualization method and single-molecule sensitive fluorescence microscopy, we quantitatively analyzed the process of miRNA maturation. Furthermore, single-particle tracking of fluorescent miRNA in cells revealed the directed movements of miRNA on cytoskeletal components (i.e., microtubules and actin filaments). Our results also suggest that cytoskeleton-dependent miRNA trafficking is associated with the interaction of miRNAs with the nucleus and the endoplasmic reticulum/Golgi apparatus. Our method should facilitate the elucidation of the mechanism and physiological significance of the subcellular localization and organelle interaction of miRNA.

Worsening physical functioning in patients with neuroinflammatory disease during the COVID-19 pandemic.

OBJECTIVE: To quantify changes in psychological wellbeing and physical function as reported by people with neurological inflammatory disease (PwNID) during the COVID-19 pandemic. METHODS: 1134 PwNID and 868 control participants were recruited through five major academic medical centers in the Northeast/Mid-Atlantic U.S. beginning in April 2020. Participants completed serial surveys throughout the COVID-19 pandemic that aimed to quantify mood symptoms and physical function, analyzed cross-sectionally with a smaller cohort analyzed longitudinally. RESULTS: Throughout the pandemic, depression scores were not significantly different between PwNID and controls, although a higher proportion of PwNID reported clinically significant depression at study entry. Depression scores did not worsen over time for either group. Loneliness was the strongest predictor of worse depression, along with older age, male gender in both PwNID and controls, as well as lack of disease modifying therapy use, and disease duration in PwNID only. In contrast, physical disability worsened significantly over time for both PwNID and controls. Age, DMT status and comorbid health conditions emerged as significant predictors of physical function. CONCLUSIONS: Depressive symptoms remained consistent for both PwNID and controls throughout the COVID-19 pandemic, but physical function worsened significantly over time for both groups. This is particularly impactful for PwNID, who have higher baseline levels of physical disability, and underscores the importance of reinstituting services and interventions that facilitate exercise and reconditioning for this population.