Extreme Inaction

The lack of microscopic red baubles adorning the two of these gothic Christmas trees to the right shows what happens when microglia – the brain’s resident immune cells – are missing a key protein called IMP1. Microglia constantly reshape their extremities to monitor the brain and clear debris. This restructuring is driven by a protein called actin (red in the microglia pictured, in usual conditions (left) and during inflammation (second image along)). A new study has identified a core mechanism of this on-site construction process: IMP1 delivers the genetic instructions for actin production to the microglia periphery, and without it no local actin production is possible, even during inflammation (fourth panel). Without actin, microglia can’t reorganise to deal with threats or clear debris. Several brain disorders are linked to microglia dysfunction, so identifying a fundamental process that controls their behaviour during inflammation might highlight a new target for neurological disease interventions.

Written by Anthony Lewis

Anthony Lewis

Writer

Ant was the web editor in the early days of BPoD, and has since worked with the UK’s top science organisations as a writer and multimedia producer. He now splits his time between freelance work and managing multimedia at The Lancet.

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• Image from work by Josune Imaz-Iruretagoyena and colleagues
• Achucarro Basque Center for Neuroscience, Leioa, Spain, Departamento de Neurociencias, Universidad del País Vasco (UPV/EHU), Leioa, Spain
• Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
• Published in PLOS Biology, November 2025