Parkin is expressed in vascular endothelial cells.

Mutations in the parkin gene are related with early-onset Parkinson's disease. Parkin is identified as an E3-ligase that combines target proteins with ubiquitin. alpha-Synuclein and synphilin-1 are substrates for E3-ligase activity of parkin and considered to be involved in the pathogenesis of Parkinson's disease. We previously demonstrated both alpha-synuclein and synphilin-1 are expressed in vascular endothelial cells (VEC). In the present study, we addressed possible expression of parkin in VEC. Parkin immunoreactivity was detected in vascular endothelial cells in postmortem human brain. Expressions of parkin mRNA and protein in human umbilical vein endothelial cells (HUVEC) were demonstrated by reverse-transcription polymerase-chain reaction (RT-PCR) and western blotting. Expression of parkin in HUVEC was not altered with tunicamycin treatment, which exerts unfolded protein stress on cells. We conclude that parkin is expressed in VEC, and that unfolded protein stress may not regulate its expression.