The timely expression of myelin basic protein gene in cultured rat brain oligodendrocytes is independent of continuous neuronal influences

Abstract

The developmental expression of the myelin basic protein (MBP) gene was studied in rat cultured oligodendrocytes using immunofluorescence and in situ hybridization. In newborn rat brain cultures, which contain only glial cells, large amounts of MBP-specific mRNA (as assayed by grain counts in autoradiograms) abruptly accumulated within immature oligodendrocytes 5 to 6 days postnatal. MBP always emerged 6 to 8 days after birth; thus, a week after, galactocerebroside (GC), an early oligodendrocyte marker, had appeared. The percentage of MBP mRNA and MBP-positive cells peaked at about 15 days postnatal and decreased thereafter. The time of emergence of MBP in these cultured oligodendrocytes appears to be determined at a very early stage in their development and independent of continuous neuronal influences. There is a striking correspondence between the times of appearance of MBP in cultured oligodendrocytes and those in the intact animal. Thus, primary cultures made from 5-day prenatal, newborn, and 2-day postnatal animals all express MBP at about the same developmental stage, namely, after 14, 8, and 6 days in culture, respectively. Furthermore, cultured oligodendrocytes obtained from the spinal cord express MBP before those obtained from midbrain or hemispheres, as they would in the intact animal. Thus, the developmental expression of the MBP gene occurs in a similar time frame in vitro and in vivo. In oligodendrocyte-enriched cultures, where 60% to 80% of the cells express MBP, in situ hybridization with the cDNA clone revealed MBP-specific mRNA in the cell body and sometimes in the processes of the differentiated oligodendrocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

The Microtubule-Associated Protein Tumor Overexpressed Gene/Cytoskeleton-Associated Protein 5 Is Necessary for Myelin Basic Protein Expression in Oligodendrocytes

“…MBP mRNA is enriched in myelin and processes of oligodendrocytes, in which MBP is preferentially located, suggesting that these are the sites of translation (Colman et al, 1982;Campagnoni et al, 1991;AmurUmarjee et al, 1997;Barbarese et al, 1999). MBP mRNA starts to accumulate in oligodendrocytes 3-4 d after their isolation from mixed cultures, and the protein can be detected 1-2 d later (Zeller et al, 1985) (our results). Other myelin-specific proteins, such as proteolipid protein (PLP) and myelin-oligodendrocytic glycoprotein (MOG), follow the same developmental pattern of expression, but, in contrast to MBP, they are synthesized in the oligodendrocyte cell body (Sorg et al, 1986;Holz et al, 1996).…”

“…TOG shRNA was injected into 4-d-old oligodendrocytes, a developmental stage at which few MBP transcripts are detectable (Zeller et al, 1985) (Fig. 3A).…”

Phosphodiesterase-Iα/autotaxin's MORFO domain regulates oligodendroglial process network formation and focal adhesion organization

“…During normal development it is associated with an increased expression of myelin proteins, such as myelin basic protein (MBP) (Zeller et al, 1985;Dubois-Dalcq et al, 1986;Hardy and Friedrich, 1996). Under experimental conditions, morphological maturation of oligodendrocytes can occur in the absence of an increase in myelin gene expression, suggesting that these two events may be regulated independently from each other (Buttery and ffrenchConstant, 1999;Osterhout et al, 1999;Sloane and Vartanian, 2007).…”

nkx2.2apromotes specification and differentiation of a myelinating subset of oligodendrocyte lineage cells in zebrafish

“…Oligodendrocytes can express MBP in the absence of axons (Mirsky et al, 1980;Bradel and Prince, 1983;Zeller et al, 1985;Dubois-Dalcq et al, 1986). Therefore, the reduction of axon wrapping and delay in mbp expression might reflect distinct roles for nkx2.2a function in myelination.…”