DJ‐1 is present in a large molecular complex in human brain tissue and interacts with α‐synuclein

DJ‐1 is a ubiquitously expressed protein involved in various cellular processes including cell proliferation, RNA‐binding, and oxidative stress. Mutations that result in loss of DJ‐1 function lead to early onset parkinsonism in humans, and DJ‐1 protein is present in pathological lesions of several tauopathies and synucleinopathies. In order to further investigate the role of DJ‐1 in human neurodegenerative disease, we have generated novel polyclonal and monoclonal antibodies to human DJ‐1 protein. We have characterized these antibodies and confirmed the pathological co‐localization of DJ‐1 with other neurodegenerative disease‐associated proteins, as well as the decrease in DJ‐1 solubility in disease tissue. In addition, we report the presence of DJ‐1 in a large molecular complex (> 2000 kDa), and provide evidence for an interaction between endogenous DJ‐1 and α‐synuclein in normal and diseased tissue. These findings provide new avenues towards the study of DJ‐1 function and how loss of its activity may lead to parkinsonism. Furthermore, our results provide further evidence for the interplay between neurodegenerative disease‐associated proteins.