OPA1, associated with autosomal dominant optic atrophy, is widely expressed in the human brain

Autosomal dominant optic atrophy (adOA) is the most prevalent hereditary optic neuropathy with moderate to severe visual field loss and loss of retinal ganglion cells. The majority of cases of adOA is associated with mutations in the OPA1 gene. Northern blot analyses showed that OPA1 is expressed in all tissues examined, with the highest transcript level in the retina and in the brain. Here we addressed the cell type-specific expression of the OPA1 protein in human brain sections using immunohistochemical techniques and Western blotting. We studied OPA1 expression in normal cerebellum and various cerebral CNS tissue specimen of different areas obtained at autopsy from patients with no reported neurological symptoms or diseases and no neuropathological alterations using a polyclonal antibody raised against a C-terminal peptide of OPA1. We found OPA1 expression in somata and dendrites of neurons of the layers II-VI of the motor cortex and frontal brain. In the cerebellar cortex, OPA1 expression was detected in the Purkinje cell layer, in the granule cell layer and in the molecular layer. Double-labeling experiments showed also OPA1 expression in GFAP-positive astrocytes. Since mutations in the OPA1 gene specifically causes optic atrophy and occurrence of cerebral anomalies in adOA patients is not characteristic, this finding may suggest different cellular susceptibility of OPA1 in brain and retinal tissues.