Expression analysis of the adOA associated protein OPA1 in the human brain

Abstract

Abstract: : Purpose:Autosomal dominant optic atrophy (adOA) is the most prevalent hereditary optic neuropathy with moderate to severe decrease of visual acuity. The majority of cases of adOA is associated with mutations in the OPA1 gene. Northern Blot analyses show that OPA1 is expressed in all tissues examined, with the highest transcript level in the retina and the second highest level in the brain. Here we addressed the cell type specific expression of the OPA1 protein in human brain sections using immunohistochemical techniques. Methods:We studied OPA1 expression in normal brains obtained at autopsy from patients with no reported neurological and neuropathological symptoms or diseases using a polyclonal antibody raised against a carboxyterminal peptide of OPA1. We analysed paraffin sections of the cerebellum and different areas of the cerebrum. Specificity of the OPA1 antibody was controlled by its inhibition by the peptide and by Western Blot analysis of human brain homogenate. Results:We found OPA1 expression in somata and dendrites of neurons of the layers II–VI of the motorcortex. In the cerebellar cortex OPA1 expression was detected in the purkinje cell layer, in the granule cell layer and in the molecular layer, which indicates a presence of OPA1 in the dendrites of the purkinje cells. Double labelling experiments will be done to show if there are also glia cells stained. Conclusions:OPA1 expression was found in selective neurons of the cerebrum and the cerebellum. Since mutations in the OPA1 gene specifically causes optic atrophy and that in adOA, simultaneous occurrence of cerebral anomalies is not characteristic, this finding suggest different roles of OPA1 in brain and retinal tissues.

Keywords: proteins encoded by disease genes • immunohistochemistry • ganglion cells