Fatty links between multisystem proteinopathy and small VCP-interacting protein.

Multisystem proteinopathy (MSP) is a rare, dominantly inherited disorder that includes a cluster of diseases, including frontotemporal dementia, inclusion body myopathy, and Paget's disease of bone. MSP is caused by mutations in the gene encoding valosin-containing protein (VCP). Patients with the same mutation, even within the same family, can present with a different combination of any or all of the above diseases, along with amyotrophic lateral sclerosis (ALS). The pleiotropic effects may be linked to the greater than 50 VCP co-factors that direct VCP's many roles in the cell. Small VCP-interacting protein (SVIP) is a small protein that directs VCP to autophagosomes and lysosomes. We found that SVIP directs VCP localization to lysosomes in an acylation-dependent manner. We demonstrate that SVIP is myristoylated at Glycine 2 and palmitoylated at Cysteines 4 and 7. Acylation of SVIP is required to mediate cell death in the presence of the MSP-associated VCP variant (R155H-VCP), whereas blocking SVIP myristoylation prevents cytotoxicity. Therefore, SVIP acylation may present a novel target in MSP.