Distribution of Striatin, a newly identified calmodulin-binding protein in the rat brain: An in situ hybridization and immunocytochemical study

Abstract

Striatin, a 110-kDa protein, is the first member of the tryptophane-aspartate 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 labeling patterns are generally concordant. Regions showing the most intense staining are the dorsal striatum, nucleus accumbens (anterior and shell parts), olfactory tubercle, red nucleus, subthalamic nucleus, cranial nerve motor nuclei, and layer IX of the spinal cord (motoneurons). Low levels of both striatin and its mRNA are detected in the cerebral cortex, thalamus, septum, amygdala, hippocampus, midbrain and cerebellum. Striatin-immunoreactive neuronal processes are found predominantly 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 axonal fiber tracts examined are devoid of striatin immunolabeling. These data show that the somatodendritic localization of striatin, previously described in the striatum, may be a main feature of the subcellular distribution of this protein throughout the CNS. Although widely distributed in neurons throughout the rat CNS, striatin is expressed prominently in the structures belonging to the motor system, suggesting that this protein may play a preponderant role in motor control.

A WD40 Repeat Protein Regulates Fungal Cell Differentiation and Can Be Replaced Functionally by the Mammalian Homologue Striatin

“…It is important to consider the subcellular localization of the PRO11 WD40 protein because mammalian homologues, such as striatin, SG2NA, and zinedin, are neuronal proteins that are strictly expressed in the somatodendritic compartments. These are found in the cytosol and are also associated with membranes (11,16,38).…”

Molecular Cloning and Characterization of Phocein, a Protein Found from the Golgi Complex to Dendritic Spines

“…Indeed, striatin, an intracellular, neuronal protein endowed with multiple protein-protein interaction domains, has a very peculiar localization, being restricted to CNS structures primarily related to locomotor activity (Castets et al, 1996;Bartoli et al 1998Bartoli et al , 1999aMoqrich et al, 1998). Furthermore, it displays a polar subcellular distribution, being strictly localized to the somato-dendritic compartment (Castets et al, 1996;Kachidian et al, 1998;Salin et al, 1998;). On the one hand, the transient blockade of striatin synthesis in embryonic motoneurons resulted in the severe impairment of dendritic growth.…”

“…The structure and composition of axons and dendrites are quite different, particularly concerning their respective plasma membranes, cytoskeleton (Gunning et al, 1998;Baas, 1999), and proteins involved in vesicular traffic, such as motor proteins (Foletti et al, 1999;Burack et al, 2000). Striatin is a neuronal, intracellular protein strictly expressed in the somato-dendritic compartment, including spines, of subsets of neurons: thus, it can be considered as a marker of neuronal polarity (Castets et al, 1996;Kachidian et al, 1998;Salin et al, 1998). Found in the cytosol as well as associated with membranes, striatin is endowed with protein-protein association modules as diverse as a caveolin-binding motif, a coiled-coil structure, a Ca 2ϩ -calmodulin-binding amphiphilic helix, and a WD-repeat domain (Castets et al, 1996;Bartoli et al, 1998Bartoli et al, , 1999bMoqrich et al, 1998).…”

A Mammalian Homolog of Yeast MOB1 Is Both a Member and a Putative Substrate of Striatin Family-Protein Phosphatase 2A Complexes

“…For example, striatin is highly abundant in the postsynaptic densities of neurons in rat brains (6,8), and striatin antisense experiments in rat neuronal cell culture (9) resulted in a decrease in the number of observed neurites. Recently, it has been shown that Rho kinase phosphorylation of vimentin on Ser-71 and Ser-38 results in neurite retraction (31), whereas Rho kinase inhibitors produce irregular neurite outgrowth.…”

“…However, more recent studies (7) indicate that SG2NA, like striatin (6,7), is primarily localized to the cytosol and the membrane. Striatin has been detected by immunofluorescence throughout neuronal dendrites, especially in the post-synaptic densities of neuronal dendritic spines (6,8). Moreover, striatin contains two polybasic domains that are absent in SG2NA and may facilitate association with the post-synaptic membrane (6).…”