alpha B-crystallin is expressed in myelinating oligodendrocytes of the developing and adult avian retina

It is well known that the expression of α B-crystallin (aBC) is increased in neurons and glia under pathologic conditions. However, the expression of aBC during the normal development of the central nervous system has not been reported. This study aimed to clarify the cell type in the chick retina in which aBC is expressed and timing of aBC expression in this cell type during development. Double immunofluorescence with cell-specific markers demonstrated that aBC was selectively expressed in oligodendrocytes (OLs) in the embryonic day 20 (E20) chick retina. A small number of aBC-expressing OLs first appeared in the nerve fiber layer of the central and peripheral retina at E16. Faint aBC expression was also observed in myelin sheaths near cell bodies in the central retina. The number of aBC-expressing OLs and intensity of aBC expression in myelin sheaths were increased in the periphery as well as in the center of the E19 retina. aBC signals in the post-hatching day 120 retina were observed in the entire nerve fiber layer. The spatiotemporal expression pattern of aBC was identical to that of myelin basic protein. These data indicate that aBC-expressing OLs are myelinating OLs among OL-lineage cells. Besides, intrayolk injection of tocopherol, an antioxidant, provoked a decrease in the levels of aBC expression in myelinating OLs. These data suggest that aBC expression in myelinating OLs responds to the change of physiological oxidative stress.