Abstract
Purpose: :
The Sox10 transcription factor belongs to the SoxE subfamily and participates in the oligodendrocyte lineage formation, differentiation and survival during development in vertebrates. Sox10, in particular, is necessary in oligodendrocyte differentiation and controls the expression of some myelin genes such as MBP. Moreover, it seems that it promotes the gene expression of factors that mediate the oligodendrocyte-axon interactions, necessary for oligodendrocyte survival. In adults, mature oligodendrocytes maintain sox10 expression keeping their glial phenotype. Here we have characterized a Sox10+population in the goldfish retina and optic nerve, a model of continuous growth and regeneration.
Methods: :
We used goldfish as controls and others injured with a cryo-lesion of the peripheral retina (CL) and an optic nerve crush (OC). They were maintained from 2 to 210 days post-injury, in accordance with the European normative for animal care. We used double immunofluorescence analyses to label oligodendrocytes (Sox10), astrocytes (GS, S100), myelin (MBP), proliferating cells (PCNA) and growing axons (Zn8), and conventional electron microscopy.
Results: :
Sox10+ cells are located in the nerve fiber layer and optic nerve head (ONH) in an increasing gradient in control conditions; which coincides with the MBP+ labeling pattern. In the ONH and optic nerve (ON), Sox10+ cells are organized in rows and they have oligodendrocyte ultrastructural features, however, they co-localize with the astrocyte GS and S100 proteins. From 7 to 21d after CL, the ONH and ON Sox10+ population is not altered, although MBP- areas corresponding with myelin degeneration in the ONH are detected. In contrast, 7-21d after OC, the number of Sox10+ cells and MBP+ profiles radically decreases in the ONH and is restored 30d after injury. Similar results are observed in the crushed area of the ON while the posterior ON suffers a delay in the loss and acquisition of myelin. Sox10-PCNA labeling shows an increase of proliferating Sox10+ cells in the ONH and ON after both injuries compared with controls.
Conclusions: :
The transcription factor Sox10 is expressed by the oligodendrocytes in the goldfish retina, ONH and ON. The Sox10+ population is highly affected after OC in the ONH and ON while small changes are detected after CL.
Keywords: glia • regeneration • optic nerve