Neuronal expression of GFAP in patients with Alzheimer pathology and identification of novel GFAP splice forms.

Glial fibrillary acidic protein (GFAP) is considered to be a highly specific marker for glia. Here, we report on the expression of GFAP in neurons in the human hippocampus. Intriguingly, this neuronal GFAP is coded by out-of-frame splice variants and its expression is associated with Alzheimer pathology. We identified three novel GFAP splice forms: Delta 135 nt, Delta exon 6 and Delta 164 nt. Neuronal GFAP is mainly observed in the pyramidal neurons of the hippocampus of Alzheimer and Down syndrome patients and aged controls, but not in neurons of patients suffering from hippocampal sclerosis. Apparently, the hippocampal neurons in patients with Alzheimer's disease pathology are capable of expressing glia-specific genes.