THE EXPRESSION OF MYRISTOYLATED ALANINE-RICH C-KINASE SUBSTRATE IN OLIGODENDROCYTES IS DEVELOPMENTALLY-REGULATED

Myristoylated alanine-rich C-kinase substrate (MARCKS), a major substr ate of activated protein kinase C (PKC), is thought to be involved in PKC-mediated signal transduction events. In the present study, we have examined the expression of MARCKS in primary cultures of rat glial ce lls. Western blot analysis of different glial cell types (i.e., astroc ytes, oligodendrocytes and microglia) revealed a relatively high level of MARCKS protein in oligodendrocytes. MARCKS protein and MARCKS mRNA levels in oligodendrocytes increased with time in culture, indicating a developmental regulation in MARCKS gene expression in differentiati ng oligodendrocytes. Immunocytochemical examination of developing olig odendrocytes indicated a strong labeling of MARCKS distributed both in the cell body and in the lacy network of processes. These findings, i n concert with our previous observations on the role of PKC in oligode ndrogenesis, strongly implicate a PKC-signaling system in oligodendroc yte development.