Apotransferrin Decreases Migration and Enhances Differentiation of Oligodendroglial Progenitor Cells in an in vitro System

Abstract

We have previously shown that a single intracranial injection of apotransferrin (aTf) in neonatal rats produces an accelerated mylinogenesis and increases the expression of certain myelin proteins such as myelin basic protein (MBP). In the present work, we studied the effects of aTf upon oligodendrocyte progenitor cell (Opc) cultures. In the presence of aTf, cells developed a multipolar morphology and showed an increased expression of O₄, MBP, O₁ and myelin-associated glycoprotein compared to controls. Migration studies using the agarose drop assay showed that aTf strongly inhibited OPc migration. This effect was not observed when an antibody against the transferrin receptor was added. The expression of two cell adhesion molecules, neural cell adhesion molecule (NCAM), N-cadherin and of polysialylated NCAM (PSA-NCAM) was evaluated by immunocytochemistry and by Western blot. Although NCAM expression did not change, there was a significant increase in N-cadherin expression and a decrease in PSA-NCAM in the aTf-treated cells. Time lapse studies of the expression of PSA-NCAM as an indicator of migration and of MBP as a marker of differentiation showed that in the cultures treated with aTf there is first a decrease in the percentage of cells expressing the former molecule which is followed by an increase in the percentage of cells expressing MBP. These results suggest that aTf added in vitro to cultured OPcs inhibits first their migration and then enhances their differentiation.

H‐ferritin is the major source of iron for oligodendrocytes

“…This pro-differentiating effect of HF was confirmed by Western, which revealed an increase in expression of both MBP and olig2 proteins, consistent with increased differentiation of these cells in response to HF treatment. These observations are in agreement with several studies, which have shown that increasing iron availability to differentiating oligodendrocytes by treatment with transferrin was able to accelerate their differentiation (Paez et al, 2002(Paez et al, , 2004(Paez et al, , 2006a. For purposes of comparison in this study, 55 ug/ml HF was effective at promoting differentiation of OPCs, whereas in the published studies for Tfn, it required 100 ug/mL to produce a similar effect (Paez et al, 2004).…”

“…As early as 1986, Bottenstein identified transferrin as one of the essential component of chemically defined medium for oligodendrocytes in culture (Bottenstein, 1986). The function of transferrin is to deliver iron to cells, although some investigators have argued that the trophic effect of transferrin is independent of iron (Adamo et al, 2006;Badaracco et al, 2008;Escobar Cabrera et al, 1997Paez et al, 2006bPaez et al, 2002).…”

Inhalation of growth factors and apo-transferrin to protect and repair the hypoxic-ischemic brain

“…We have reported that a single intracranial injection of aTf upregulates the expression of diverse myelin constituents and significantly increases myelin deposition, especially in areas close to the lateral ventricles in rats [32,33]. This promyelinating effect was also seen in primary cultures of oligodendrocytes [34], as well as in oligodendroglial cell lines treated with aTf [35,36]. We have demonstrated that aTf modulates the expression of myelin basic protein (MBP) through different signaling pathways and, furthermore, we have shown that aTf overexpression promotes oligodendrocyte differentiation and myelination of cortical neurons [36,37].These data have been confirmed by other authors who showed that aTf regulates MBP expression [38] and that transgenic mice overexpressing the human Tf gene in the CNS evidence increased myelination [39].…”

Apotransferrin promotes the differentiation of two oligodendroglial cell lines

“…During development, OLGcs synthesize and secrete transferrin (Tf), an iron carrier glycoprotein shown to be an essential factor for myelination (Espinosa de los Monteros, 1989Monteros, , 1999Marta et al, 2000). Recently, we demonstrated that with the addition of apotransferrin (aTf) to OLGc primary cul-tures, the cells developed a multipolar morphology and showed an increased expression of O4, MBP, galactocerebroside (GC), and myelin-associated glycoprotein (MAG) compared to controls (Paez et al, 2002).…”