Dystrophin immunoreactivity in normal and duchenne human fetal neurons in culture

Abstract

Dystrophin, the protein product defective in Duchenne muscular dystrophy (DMD), is present in all types of muscle and in the brain. The function of the protein is unknown and its role in the brain is unclear, although 30% of DMD patients show nonprogressive mental retardation. We have therefore studied the localisation of dystrophin in cultures of normal and DMD human fetal neurons using antibodies raised to different regions of the protein. Dystrophin immunoreactivity was demonstrated in the soma and axon hillock of normal neurons and appeared to be associated with the inner part of the cell membrane, although some intracellular staining was also observed. Positive dystrophin staining was present only in cells with fully developed neuronal features, although not all the neurons were positive. Glial cells were always negative for the antigen. Immunostaining with antibodies to the brain spectrins indicate that the dystrophin antibodies did not crossreact with these proteins. The possibility of cross-reactivity with other proteins is discussed. Studies of cells cultured from a DMD fetus also showed specific dystrophin immunostaining in neurons, although the muscle was generally negative for dystrophin. However, the localisation of dystrophin immunostaining and that of the brain spectrins and neurofilaments appeared abnormal, as did the overall morphology of the cells. This suggests that dystrophin may play a role during brain development and dystrophin deficiency results in abnormal neuronal features. This would be consistent with the nonprogressive nature of the mental retardation observed in DMD patients.

Immunofluorescence mapping of dystrophin in the rat brain: astrocytes contain the splice variant Dp71f, but this is confined to subpopulations

“…In astrocytoma Dp71f was found in the lamellipodia, with focal complexes, actin and integrin (Garcia-Tovar et al 2002). A similar pattern was observed in cultures of immature neurons (Mussini et al 1995;Torelli et al 1992). According to Garcia-Tovar et al (2001) Dys2 did not colocalize with the GFAP antibody, although it did with neurofilaments, whereas 5F3 immunoreactivity even in neurons does not co-localize with microtubules or intermediate filaments.…”

“…The results of Rowilski et al (1996) concur with this latter finding. In vitro, Torelli et al (1992) found that, in human cell culture, only neurons, not glial cells, were immunoreactive to dystrophin. Subcellular fractionation and ultrastructural studies have even revealed the binding of both full-length dystrophin and Dp71 to the cell membrane, including synaptic membranes (Jung et al 1993;Lidov et al 1990).…”

Subcellular localization of Dp71 dystrophin isoforms in cultured hippocampal neurons and forebrain astrocytes

“…As Dp71d is the most abundant dystrophin short product in the brain, and seems to be associated with the cytoplasmic NF reticulum, its absence or a structural change of this protein in DMD patients may induce alterations in its subcellular distribution and interactions with NFs, as has been detected by Torelli et al (1992). This type of change may also contribute to alterations in the cognitive functions observed in some DMD patients.…”

Immunocytochemical Study of Dystrophin-Related Protein in the Rat Retina

“…It has been known that dystrophin exists in neuronal cells, but not in glial cells [21][22][23][24][25], Moreover, its localization is restricted to the plasma membrane of cell bodies and den drites, especially at the postsynaptic mem brane, but not in the axoplasm. Miike et al [16] firstly reported that the dystrophin ex isted in the OPL of mouse and rat retinas.…”