An unconventional role for miRNA: let-7 activates Toll-like receptor 7 and causes neurodegeneration

In addition to their function in gene regulation, certain microRNAs can be secreted by cells. Here, the authors show that the microRNA let-7 can cause neurodegeneration by directly activating Toll-like receptor 7 and that individuals with Alzheimer's disease have more let-7b in their cerebrospinal fluid.