|Deficits in auditory processing, among the best documented endophenotypes in schizophrenia, are possibly due to loss of excitatory synaptic connections. Dendritic spines, the principal post-synaptic target of excitatory projections, are reduced in schizophrenia. p21-activated kinase (PAK1) regulates both the actin cytoskeleton and dendritic spine density, and is a downstream effector of both Kalirin and CDC42, both of which have altered expression in schizophrenia. This study sought to determine if there is decreased PAK1 protein expression in schizophrenia through the use of quantitative western blots of 25 schizophrenia subjects and matched controls. There was no significant change in PAK1 level detected in the schizophrenia subjects in our cohort. PAK1 protein levels within subject pairs correlated positively with prior measures of total Kalirin protein in the same pairs. Evaluation of PAK1 protein expression in a mouse model of postmortem interval revealed it to be relatively stable over the intervals present in our human cohort. These latter two findings suggest that the lack of change in PAK1 level in schizophrenia is not due to limited sensitivity of our assay to detect meaningful differences in PAK1 protein expression. Future studies are needed to evaluate whether alterations in PAK1 phosphorylation states, or alterations in protein expression of other members of the PAK family (figure), are present in schizophrenia.
|Deo A, Goldszer I, Li S, Henteleff R, Sampson A, Lewis D, Penzes P, Sweet R: PAK1 Protein Expression in the Auditory Cortex of Schizophrenia Subjects. PLoS ONE 7:e43904, 2012.