Proteomic identification of differentially expressed genes during differentiation of cynomolgus monkey (Macaca fascicularis) embryonic stem cells to astrocyte progenitor cells in vitro.

Understanding astrocytogenesis is valuable for the treatment of nervous system disorders, as astrocytes provide structural, metabolic and defense support to neurons, and regulate neurons actively. However, there is limited information about the molecular events associated with the differentiation from primate ES cells to astrocytes. We therefore investigated the differentially expressed proteins in early astrocytogenesis, from cynomolgus monkey ES cells (CMK6 cell line) into astrocyte progenitor (AstP) cells via the formation of primitive neural stem spheres (Day 4), mature neural stem spheres (NSS), and neural stem (NS) cells in vitro, using two-dimensional gel electrophoresis (2-DE) and liquid chromatography-tandem mass spectrometry (LC-MS-MS). We identified 66 differentially expressed proteins involved in these five differentiation stages. Together with the results of Western blotting, RT-PCR, and a search of metabolic pathways related to the identified proteins, these results indicated that collapsin response mediator protein 2 (CRMP2), its phosphorylated forms, and cellular retinoic acid binding protein 1 (CRABP1) were upregulated from ES cells to Day 4 and NSS cells, to which differentiation stages apoptosis-associated proteins such as caspases were possibly related; Phosphorylated CRMP2s were further upregulated but CRABP1 was downregulated from NSS cells to NS cells, during which differentiation stage considerable axon guidance proteins for development of growth cones, axon attraction, and repulsion were possibly readied; Nonphosphorylated CRMP2 was downregulated but CRABP1 was re-upregulated from NS cells to AstP cells, in which differentiation stage reorganization of actin cytoskeleton linked to focal adhesion was possibly accompanied. These results provide insight into the molecular basis of early astrocytogenesis in monkey.