Vanishin is a novel ubiquitinylated death-effector domain protein that blocks ERK activation

The ERK (extracellular-signal regulated-kinase)/MAPK (mitogen-activated protein kinase) pathway can regulate transcription, proliferation, migration and apoptosis. The small DED (death-effector domain) protein PEA-15 (phosphoprotein enriched in astrocytes-15) binds ERK and targets it to the cytoplasm. Other DED-containing proteins including cFLIP and DEDD can also regulate signal transduction events and transcription in addition to apoptosis. In the present study, we report the identification of a novel DED-containing protein called Vanishin. The amino acid sequence of Vanishin is closest in similarly to PEA-15 (61% identical). Vanishin mRNA is expressed in several mouse tissues and in both mouse and human cell lines. Interestingly, Vanishin is regulated by ubiquitinylation and subsequent degradation by the 26 S proteasome. The ubiquitinylation is complex and occurs at both the internal lysine residues and the N-terminus. We further show that Vanishin binds ERK/MAPK but not the DED proteins Fas-associated death domain, caspase 8 or PEA-15. Vanishin is present in both the nucleus and Golgi on overexpression and forces increased ERK accumulation in the nucleus in the absence of ERK stimulation. Moreover, Vanishin expression inhibits ERK activation and ERK-dependent transcription in cells, but does not alter MAPK/ERK activity. Therefore Vanishin is a novel regulator of ERK that is controlled by ubiquitinylation.