Comparative proteomics in the corpus callosal sub-regions of postmortem human brain.

The corpus callosum (CC) is a single anatomical region with homologous cytoarchitecture and divided into four sub-regions such as the rostrum, the genu, the body and the splenium. Neuroimaging analysis revealed that susceptibility to clinical neurological diseases of these sub-regions is variable, indicating biochemical and physiological heterogenecity. To understand the biochemical make up of these regions, we compared the protein expression of these three sub-regional areas [the genu, the body and the splenium (n=9)] through 2D proteomics, which is a high-throughput global protein expression analysis technique. Normative proteomic comparison of gels, and analysis of spectra revealed that 17 (identified as 7 proteins), 35 (identified as 20 proteins) and 39 (identified as 21 proteins) protein spots were differentially expressed in the genu vs. the body, the genu vs. the splenium and the body vs. the splenium, respectively. These results suggest that the sub-regions of the CC differ at the level of protein expression. Identified proteins of the different groups belong to several functional classes such as cytoskeletal, metabolic, signaling, oxidative stress and calcium regulation. Interestingly, oxidative stress defense and glucose metabolic pathways of the splenium are quite different from the genu which might be correlated to region specific vulnerability of neuronal illness. Protein expression maps of these regions can be used as a reference source for future studies to investigate the molecular basis of functional differences and degree of pathogenesis of various neurodegenerative diseases of the CC.