An organelle proteomic method to study neurotransmission-related proteins, applied to a neurodevelopmental model of schizophrenia.

Limited information is currently available on molecular events that underlie schizophrenia-like behaviors in animal models. Accordingly, we developed an organelle proteomic approach enabling the study of neurotransmission-related proteins in the prefrontal cortex (PFC) of postpubertal (postnatal day 60 (PD60)) neonatally ventral hippocampal (nVH) lesioned rats, an extensively used neurodevelopmental model of schizophrenia-like behaviors. The PFC was chosen because of its purported role in the etiology of the disease. Statistical analysis of 392 reproducible spots on 2-D organelle proteomic patterns revealed significant changes in intensity of 18 proteinous spots in plasma membrane-enriched fractions obtained from postpubertal nVH lesioned rats compared to controls. Mass spectrometric analysis and database searching allowed the identification of a single protein in each of the nine differential spots, including proteins of low abundance, such as neurocalcin delta. Most of the identified dysregulated proteins, including clathrin light chain B, syntaxin binding protein 1b and visinin-like protein 1 are known to be linked to various neurotransmitter systems and to play key roles in plasma membrane receptor expression and recycling as well as synaptic vesicle exocytosis/recycling. Organelle proteomic approaches have hence proved to be most useful to identify key proteins linked to a given behavior in animal models of brain diseases.

Early dysregulation of hippocampal proteins in transgenic rats with Alzheimer's disease-linked mutations in amyloid precursor protein and presenilin 1.

The response of the hippocampal proteome to expression of mutant proteins present in familial forms of Alzheimer's disease (AD) was studied using transgenic rats. These animals carry both the amyloid precursor protein Swedish and 717 mutation (APP(SW+717)) as well as the presenilin 1 Finnish mutation (PS1(FINN)). This transgenic rat model displays intracellular amyloid beta (Abeta) in neurons of the neocortex and the hippocampus (CA2 and CA3). The hippocampus was selected as it is one of the first brain regions affected in AD and is involved in the processing of short-term memory and spatial memory. Applying a proteomic approach, we demonstrate that the expression of APP(SW+717) and PS1(FINN) transgenes causes changes in expression of hippocampal proteins, some of which have been previously linked to learning and memory formation. The protein alterations documented here occur in the absence of plaque formation and prior to the onset of cognitive deficits later observed in these transgenic rats. This indicates that molecular changes take place in the hippocampal neurons in response to expression of mutant proteins APP(SW+717) and PS1(FINN), which precede the occurrence of overt extracellular accumulation of extracellular amyloid. The implications of these findings on our understanding of the early stages of AD are discussed.

Proteomic approaches in brain research and neuropharmacology.

Numerous applications of genomic technologies have enabled the assembly of unprecedented inventories of genes, expressed in cells under specific physiological and pathophysiological conditions. Complementing the valuable information generated through functional genomics with the integrative knowledge of protein expression and function should enable the development of more efficient diagnostic tools and therapeutic agents. Proteomic analyses are particularly suitable to elucidate posttranslational modifications, expression levels and protein-protein interactions of thousands of proteins at a time. In this review, two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) investigations of brain tissues in neurodegenerative diseases such as Alzheimer's disease, Down syndrome and schizophrenia, and the construction of 2D-PAGE proteome maps of the brain are discussed. The role of the Human Proteome Organization (HUPO) as an international coordinating organization for proteomic efforts, as well as challenges for proteomic technologies and data analysis are also addressed. It is expected that the use of proteomic strategies will have significant impact in neuropharmacology over the coming decade.