Emerging extranuclear roles of protein SUMOylation in neuronal function and dysfunction

Post-translational protein modifications are integral components of signalling cascades that enable cells to efficiently, rapidly and reversibly respond to extracellular stimuli. These modifications have crucial roles in the CNS, where the communication between neurons is particularly complex. SUMOylation is a post-translational modification in which a member of the small ubiquitin-like modifier (SUMO) family of proteins is conjugated to lysine residues in target proteins. It is well established that SUMOylation controls many aspects of nuclear function, but it is now clear that it is also a key determinant in many extranuclear neuronal processes, and it has also been implicated in a wide range of neuropathological conditions

Redefining the Chaperone Mechanism of sHsps: Not Just Holdase Chaperones

The small heat-shock proteins (sHsps) are molecular chaperones that play a fundamental role in maintaining cellular protein homeostasis (proteostasis) by preventing the aggregation of destabilised proteins. They are generally described as \u27holdase\u27 type chaperones since they have the ability to bind partially folded intermediate states of target proteins, in an ATP-independent manner, and, in doing so, they can form high molecular weight complexes with some of them. However, recent work has shown that the ability of sHsps to interact with target proteins is multi-faceted. This review highlights the mechanisms by which sHsps can interact with aggregation-prone target proteins and proposes that they should be considered as protein \u27stabilisers\u27 rather than \u27holdase\u27 chaperones