The Proteome Profiles of the Cerebellum of Juvenile, Adult and Aged Rats--An Ontogenetic Study

Abstract

In this study, we searched for proteins that change their expression in the cerebellum (Ce) of rats during ontogenesis. This study focuses on the question of whether specific proteins exist which are differentially expressed with regard to postnatal stages of development. A better characterization of the microenvironment and its development may result from these study findings. A differential two-dimensional polyacrylamide gel electrophoresis (2DE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis of the samples revealed that the number of proteins of the functional classes differed depending on the developmental stages. Especially members of the functional classes of biosynthesis, regulatory proteins, chaperones and structural proteins show the highest differential expression within the analyzed stages of development. Therefore, members of these functional protein groups seem to be involved in the development and differentiation of the Ce within the analyzed development stages. In this study, changes in the expression of proteins in the Ce at different postnatal developmental stages (postnatal days (P) 7, 90, and 637) could be observed. At the same time, an identification of proteins which are involved in cell migration and differentiation was possible. Especially proteins involved in processes of the biosynthesis and regulation, the dynamic organization of the cytoskeleton as well as chaperones showed a high amount of differentially expressed proteins between the analyzed dates.

Keywords: brain; cerebellum; development; proteomics; rat.

Figure 1

Overview of the reference gel images from the Ce. The Coomassie blue stainings of the gels have similar intensities. The 2DE-gel image of a P7 animal is shown in (a); In (b) the 2DE-gel image of a P90 animal is presented; (c) Shows the 2DE-gel image of an old P637 rat.

Figure 2

In order to perform an accurate segmentation of spots, the manual editing of spots was augmented by a 3D-visualization. This procedure has been applied to all reference gels as well as to all template gels. An example of the latter is presented here. The green box on the left indicates a region which is visualized as a 3D-view on the right side. The yellow circle is a temporary marker of the PG200.

Figure 3

Differential expression of proteins in the Ce at P7. (A) Relative frequencies of proteins in the Ce that are differentially expressed (P7 vs. P90); (B) Number of differentially expressed proteins of different protein categories within the Ce (P7) vs. (P90). (Abbreviations for Figure 3B and Figure 4B, pcm: proteins carbohydrate metabolism, paam: proteins amino acid metabolism, pfm: proteins fat metabolism, pem: proteins energy metabolism, pd: proteins degradation, pa: proteins antioxidants, ptm: proteins transmitter metabolism, pb: proteins biosynthesis, pst: proteins signal transduction, pr: proteins regulation, cp: chaperones, sp: structural proteins, tp: transport proteins).

Figure 4

Differential expression of proteins in the Ce at P637. (A) Relative frequencies of proteins in the Ce that are differentially expressed (P637 vs. P90); (B) Number of differentially expressed proteins of different protein categories within the Ce (P637) vs. (P90). Same abbreviations performed as in Figure 3B.