In Science this week, a team from the Cincinnati Children's Hospital Research Foundation reports on the discovery that the interaction between a microRNA known as let-7 and a gene called lin-41 is partly responsible for why aging neurons lose the ability to regenerate. The scientists found that in Caenorhabditis elegans, let-7 inhibits the expression of lin-41, which helps promote neuron regeneration in older anterior ventral microtubule neurons. In younger neurons, however, lin-41 appears to block let-7 expression. "This reciprocal inhibition ensures that axon regeneration is inhibited only in older neurons," the researchers write. "These findings show that a let-7–lin-41 regulatory circuit, which was previously shown to control timing of events in mitotic stem cell lineages, is reutilized in postmitotic neurons to control postdifferentiation events."
Meanwhile, in Science Translational Medicine, a team of academic and industry scientists publish details about a set of genetic signatures that may provide predictive information about breast cancer. As part of a competition with other groups, the researchers developed a new computational model for gene signature analysis, and trained it using genomic and clinical data from more than a thousand women diagnosed with breast cancer. They then tested it using a new dataset from 184 women breast cancer and found that it could predict patient survival compared with other entries in the competition.