Tunnelling nanotubes: A highway for prion spreading?

The discovery of tunnelling nanotubes (TNTs) and their proposed role in long intercellular transport of organelles, bacteria and viruses have led us to examine their potential role during prion spreading. We have recently shown that these membrane bridges can form between neuronal cells, as well as between dendritic cells and primary neurons and that both endogenous and exogenous PrP(Sc) appear to traffic through these structures between infected and non-infected cells. Furthermore, prion infection can be efficiently transmitted from infected dendritic cells to primary neurons only in co-culture conditions permissive for TNT formation. Therefore, we propose a role for TNTs during prion spreading from the periphery to the central nervous system (CNS). Here, we discuss some of the key steps where TNTs might play a role during prion neuroinvasion.