DISTRIBUTION OF STRIATIN, A NEWLY IDENTIFIED CALMODULIN-BINDING PROTEIN IN THE RAT-BRAIN - AN IN-SITU HYBRIDIZATION AND IMMUNOCYTOCHEMICAL STUDY

Striatin, a 110-kDa protein, is the first member of the tryptophane-as partate repeat protein family known to bind calmodulin in the presence of Ca2+. We examined the distribution of striatin and its mRNA in the rat central nervous system (CNS) by using immunocytochemistry and in situ hybridization, respectively. Striatin immunostaining and mRNA lab eling patterns are generally concordant. Regions showing the most inte nse staining are the dorsal striatum, nucleus accumbens (anterior and shell parts), olfactory tubercle, red nucleus, subthalamic nucleus, cr anial nerve motor nuclei, and layer IX of the spinal cord (motoneurons ). Low levels of both striatin and its mRNA are detected in the cerebr al cortex, thalamus, septum, amygdala, hippocampus, midbrain and cereb ellum. Striatin-immunoreactive neuronal processes are found predominan tly in the structures containing striatin-positive neurons, suggesting that these labeled processes represent dendritic arborization rather than axonal processes. Except for the medial forebrain bundle, all axo nal fiber tracts examined are devoid of striatin immunolabeling. These data show that the somatodendritic localization of striatin, previous ly described in the striatum, may be a main feature of the subcellular distribution of this protein throughout the CNS. Although widely dist ributed in neurons throughout the rat CNS, striatin is expressed promi nently in the structures belonging to the motor system, suggesting tha t this protein may play a preponderant role in motor control. (C) 1998 Wiley-Liss, Inc.