The walking dead: sequential nuclear and organelle destruction during hair development

Summary Shiny, thick, smooth, bouncy, bright; everyone wants healthy looking hair. Ironically this vivacious, healthy hair is actually dead! The building blocks of hair begin life as active cells busily moving, dividing and making all sorts of molecules in order to stay alive. However, to turn into “hair” they need to pack themselves full of fibres known as “keratin” to make them tough and strong. To make space for this “keratin” the cell first has to have a spring clean and throw away all of its contents including its brain (nucleus) and lungs (mitochondria). This study aimed to find out more about this mysterious process. Samples of hair follicles (hair plus surrounding scalp) were taken from healthy volunteers in a process much like coring an apple. These samples were then stained using specific chemicals to look at hair cells using a very powerful microscope. These studies found that the spring cleaning process of hair cells happened in a surprisingly organized way and all within the first 1mm of hair follicle deep in the scalp. First the cells threw away their nucleus, or “brain”, meaning that they could no longer make decisions, much like a zombie. However, these cells could continue to “breathe” as they still had their mitochondria, or “lungs”. These zombie cells had one singular role which was to fill themselves full of keratin, throwing away their “lungs” at the last minute, when no further space remained. This discovery is not only interesting but informs hair scientists to target the first 1mm of the hair follicle when developing treatments to prevent hair thinning, greying and hair loss.