engleski

Domain analysis of TRIOBP-1 implies a common basis underlying its actin polymerization activity and its aggregation in schizophrenia

The presence of aggregates of specific proteins in the brain can be used to characterize multiple neurodegenerative conditions, and arises as a result of imbalances in protein homeostasis during the development of the condition. We have previously proposed that similar protein deposits may arise in subsets of patients suffering from chronic mental illness, and were able to determine that proteins produced by two established schizophrenia risk factors, DISC1 and dysbindin, could be seen to aggregate specifically in the brains of a subset of patients with major mental illness. To detect other such proteins not previously implicated by genetics, we employed an antibody proteomics approach, identifying TRIOBP-1 as an additional protein which putatively shows schizophrenia-specific aggregation in the brain. The propensity for both over-expressed and endogenous TRIOBP-1 protein to aggregate was then confirmed in a variety of systems. The TRIOBP-1 protein is predicted to consist of an N-terminal Pleckstrin homology domain, as well as extensive predicted coiled-coil regions. In order to investigate the domain structure of TRIOBP-1 in more depth, and specifically in order to determine which elements of the protein were implicated in both its normal function and in its aggregation propensity, a large number of constructs were subcloned containing combinations of structural elements of TRIOBP-1. These were expressed in both neuroblastoma cell lines and in E. coli for recombinant protein production. In this manner, we have now identified a central segment of the protein, as being critical for the aggregation of the coiled-coil C-terminal segment of TRIOBP-1. The N-terminal section of TRIOBP-1 shows no such propensity, but was seen to be localized to the actin cytoskeleton by this same central region, implying a common underlying relationship between the aggregation and actin-binding features of TRIOBP-1. We have also found the first evidence that the N- and C-terminal portions of TRIOBP-1 may play distinct roles in the promotion of actin polymerization by TRIOBP-1. Experiments to confirm the relevance of TRIOBP-1 aggregation to schizophrenia in the wider population are currently underway. Through probing a protein misfolding event seemingly present in at least a subset of patients, we hope to determine both its potential utility as a biomarker, and more generally to understand a physiological element of chronic mental illness which has the potential to lie downstream of both genetic and environmental risk factors.

TRIOBP ; Tara ; Aggregation ; Mental illness ; Schizophrenia

nije evidentirano