Nuclear microRNA-mediated transcriptional control determines adult microglial homeostasis and brain function.

Microglia are versatile regulators in brain development and disorders. Emerging evidence links microRNA (miRNA)-mediated regulation to microglial function; however, the exact underlying mechanism remains largely unknown. Here, we uncover the enrichment of miR-137, a neuropsychiatric-disorder-associated miRNA, in the microglial nucleus, and reveal its unexpected nuclear functions in maintaining the microglial global transcriptomic state, phagocytosis, and inflammatory response. Mechanistically, microglial Mir137 deletion increases chromatin accessibility, which contains binding motifs for the microglial master transcription factor Pu.1. Through biochemical and bioinformatics analyses, we propose that miR-137 modulates Pu.1-mediated gene expression by suppressing Pu.1 binding to chromatin. Importantly, we find that increased Pu.1 binding upregulates the target gene Jdp2 (Jun dimerization protein 2) and that knockdown of Jdp2 significantly suppresses the impaired phagocytosis and pro-inflammatory response in Mir137 knockout microglia. Collectively, our study provides evidence supporting the notion that nuclear miR-137 acts as a transcriptional modulator and that this microglia-specific function is essential for maintaining normal adult brain function.

Preparation and properties of nanometer titanium dioxide/silk fibroin blend membrane.

A novel nanometer titanium dioxide (nanoTD)/silk fibroin (SF) blend membrane was prepared and characterized by AFM, FTIR, DSC, and XRD. The strength, solubility and thermal properties and the antibacterial activity of the blend membrane were then investigated. The results show that at a nanoTD/SF weight ratio of 0.1%, nanoTD particles were evenly dispersed in the blend membrane. The blend membrane exhibited a crystalline 2theta XRD peak at 21.1 degrees and the decomposition temperature was 28.72 degrees C higher than for a pure SF membrane. The results show that the blend membrane had higher crystallinity and better antibacterial activity and strength than a pure SF membrane, whereas its solubility was lower.