PLECTIN IN THE HUMAN CENTRAL-NERVOUS-SYSTEM - PREDOMINANT EXPRESSION AT PIA GLIA AND ENDOTHELIA/GLIA INTERFACES/

Plectin is a high molecular weight protein that serves as a versatile cytoskeletal cross-linker molecule. Mutations of the human plectin gen e have recently been identified to cause the autosomal recessive disor der epidermolysis bullosa simplex with muscular dystrophy (EBS-MD). A subgroup of EBS-MD patients display signs of a neurodegenerative disor der suggesting that the expression of defective plectin may also inter fere with the structural and functional integrity of the human central nervous system. However, the expression pattern of plectin in the hum an brain is still unknown. We therefore analyzed the immunohistochemic al distribution of plectin in normal hippocampal specimens obtained at autopsy and in neocortical and hippocampal tissue of patients who had undergone epilepsy surgery. In general, plectin-immunoreactive cells were identified as capillary endothelia and astrocytes. A striking fea ture seen in all specimens was the accentuated plectin immunoreactivit y of astrocytic end feet abutting on blood vessels and on the pial sur face. Furthermore, the analysis of hippocampal tissue of epilepsy pati ents with Ammon's horn sclerosis (AHS) revealed a strong plectin label ing of reactive astrocytes. The latter finding suggests that the up-re gulation of plectin, which parallels the increase of glial fibrillary acidic protein, may be a general feature of reactive astroglia. The pr edominant expression of plectin at pia/glia and endothelia/glia interf aces in the human brain indicates that plectin may have an integral ro le in the structural organization of the blood-brain barrier and the l eptomeninges.