Changes in the Expression of Cytoskeletal Proteins in the CNS of Transferrin Transgenic Mice

Self Cite

Mechanisms that regulate oligodendroglial cell (OLGc) differentiation are the focus of intensive research in the field of cellular and molecular neurobiology. We have previously shown that the addition of apotransferrin (aTf) to primary OLGc cultures accelerates their differentiation and induces an increase in the expression of different components of the myelin cytoskeleton (CSK) such as actin, tubulin, and some of the microtubule-associated proteins, particularly the stable tubulin only peptide (STOP). Fyn protein-tyrosine kinase (Fyn kinase), a member of the Src family, participates in signalling pathways that regulate OLGs/myelin cytoskeletal reorganization. It is essential for myelin development in the central nervous system (CNS), and its absence results in hypomyelination. In the present study, we used both primary cell and N19 cell line cultures to investigate further the mechanisms of action involved in the accelerated differentiation of OLGcs induced by aTf. In particular, we were interested in studying the participation of Fyn kinase in the different pathways involved in the reorganization of the OLGc/myelin cytoskeleton. In agreement with results already published, we found that in OLGcs, Fyn kinase is associated with Tau and tubulin. Using a dominant-negative of Tau in which the Fyn-Tau-microtubules (MTs) interaction is blocked, we found that aTf was unable to induce OLGc morphological differentiation. It was also observed that aTf decreases the activated RhoA content in coincidence with a redistribution of actin immunoreactivity. These results give support to our hypothesis that Fyn kinase plays a key role in the differentiation process of OLGcs promoted by aTf.

supporting

confidence: 87%

Fyn kinase is involved in oligodendroglial cell differentiation induced by apotransferrin

Pérez

Ortiz

Roffé

et al. 2008

Self Cite

“…The effects were more pronounced at 10 days and the changes occurred before the increase of MBP and CNPase mRNA. The development of a human transferrin transgenic mouse by Saleh et al (2003) confirmed the abovementioned results and allowed us to study the effects of a sustained overexpression of the human transferrin gene on the CSK of OLGcs (Marta et al, 2002a).…”

Section: Discussionsupporting

confidence: 61%

“…Transgenic mice overexpressing the human transferrin gene also show an increase in the immunoreactivity of certain CSK proteins (Marta et al, 2002a), specifically in areas enriched in myelinated axons such as the corpus callosum. The molecular mechanisms involved in the action of aTf on the CNS, particularly the role of the CSK and of second messengers has been studied recently in our laboratories (Marta et al, 2002b).…”

mentioning

confidence: 99%

Apotransferrin and the cytoskeleton of oligodendroglial cells

Ortiz

Pasquini

Soto

et al. 2005

Apotransferrin (aTf), has been shown to accelerate the differentiation of oligodendroglial cells (OLGcs) in primary cultures and to increase the expression of different components of the myelin cytoskeleton (CSK). We examined the incorporation and distribution of human aTf (aTfh) exogenously added to OLGcs cultures and its effects on the CSK of the OLGcs. When OLGcs treated with aTfh were extracted with a CSK-stabilizing buffer containing detergent, aTfh was found in the soluble fraction. In vitro experiments showed that purified tubulin was not altered by the addition of aTfh. In OLGc primary cultures treated with aTfh, this glycoprotein showed a punctate distribution pattern along the OLGc processes. Treatment of the cultures with colchicine, cytochalasin, or taxol induced a displacement of the immunoreactivity of aTfh toward the OLGc soma. Analysis of the effects of aTfh on the cell distribution of tyrosinated and detyrosinated tubulin and STOP (stable tubule only polypeptide), showed that aTfh added to OLGc cultures promoted changes suggesting a stabilizing effect on the microtubules (MT) at the tip of the processes. Kinesin and dynein were found to colocalize with the aTfh, indicating that these motors participate in the transport of the added glycoprotein. Moreover, after treatment with aTfh, clathrin immunoreactivity was displaced from the OLGc body toward the cell processes. These results indicate that although aTfh added to OLGcs does not interact directly with CSK components, it seems to be transported in clathrin coated vesicles from the cell body to the tips of the OLGc processes where it promotes their stabilization. This mechanism may be of importance in the increased formation of the myelin membrane induced by aTf.

“…Beaulieu (2002) observed that factors modulating the fast axonal transport change the axial diffusivities of water. This observation was supported by Marta et al (2002), who showed that the continuous overexpression of Tf might induce some neuronal changes in the adult.…”

Section: Discussionsupporting

confidence: 56%

Oligodendrocyte differentiation is increased in transferrin transgenic mice

Sow¹,

Lamant²,

Bonny³

et al. 2006

Transferrin (Tf), the iron transport glycoprotein found in biological fluids of vertebrates, is synthesized mainly by hepatocytes. Tf is also synthesized by oligodendrocytes (Ol), and several lines of evidence indicate that brain Tf could be involved in myelinogenesis. Because Tf is postnatally expressed in the brain, we sought to investigate whether Tf could intervene in Ol differentiation. For this purpose, we analyzed transgenic mice overexpressing the complete human Tf gene in Ol. We show that the hTf transgene was expressed only from 5 days postpartum onward. In the brain of 14-day-old transgenic mice, the DM-20 mRNA level was decreased, whereas the PLP, MBP, CNP, and MAG mRNA levels were increased. We counted a higher proportion of Ol expressing the O4 (Ol-specific antigens) and PLP in brain cells cultured from transgenic mice. These results support the idea that overexpressing Tf in the brain accelerates the oligodendrocyte lineage maturation. Accordingly, by NMR imaging acquisition of diffusion tensor in hTf transgenic mice, we observed early maturation of the cerebellum and spinal cord and more myelination in the corpus callosum. In addition, hTf overexpression led to an increase in Sox10 mRNA and protein. Increases in Sox10 and in Tf expression occur simultaneously during brain development. The Olig1 mRNA level also increased, but long after the rise of hTf and Sox10. The Olig2 mRNA level remained unchanged in the brain of transgenic mice. Our findings suggest that Tf could influence oligodendrocyte progenitor differentiation in the CNS.