Functional roles of S100 proteins, calcium-binding proteins of the EF-hand type

The cytological and topographical distribution of S-100 and glial fibrillary acidic (GFA) proteins in the adult rat brain has been compared using the horseradish peroxidase-labelled antibody technique. Both proteins are present in astrocytes and structures composed of astrocytic processes, namely the glial limitans and the perivascular membranes, but the cytological localization varies between the two proteins. S-100 is found in the nucleus and cytoplasm whereas GFA protein is confined to the cytoplasm. Neither is found in neurons, but S-100 is present in some oligodendroglia, suggesting a general regulatory role in glia. Although GFA protein in present in both protoplasmic and fibrous astrocytes, it is more prominent in the latter, confirming its association with astrocytic filaments.

The topographical distribution of S‐100 and GFA proteins in the adult rat brain: An immunohistochemical study using horseradish peroxidase‐labelled antibodies

Autoradiographic demonstration of ocular-dominance columns in the monkey striate cortex by means of transneuronal transport.

Isoelectric points and molecular weights of proteins.

The study involved 77 myxopapillary ependymomas of the spinal cord encountered during a 60-year period (1924-1983). This variant of ependymoma was, with few exceptions, limited to the lumbosacral region, particularly the filum terminale. The male:female ratio was 1.7:1, and the mean age at diagnosis was 36.4 years (range, 6-82); at presentation, 15 (19%) of the patients were in the first two decades of life. The duration of symptoms ranged from 1 month to 30 years; the most frequent complaint was low-back pain, and eight patients had undergone prior "disc surgery." Generally, myelographic block was disclosed. Preoperative cerebrospinal fluid protein levels averaged 2462 mg/dl. Myxopapillary ependymomas are slow-growing tumors that show no significant tendency to histologic dedifferentiation. Despite some variation in cytologic features and the presence of atypia and modest mitotic activity in most cases, the gross characteristics of the tumors appear to be of greater prognostic significance than the histologic features. Tumors that were encapsulated (25%) and amenable to intact, total surgical removal had a recurrence rate of 10%, whereas those that were removed either piecemeal (34%) or subtotally (41%) had recurrence rates of 19%. Overall survival, however, was more closely related to residual disease; total removal of tumor, whether intact (encapsulated) or piecemeal, resulted in longer survival (19 years) than did subtotal resection (14 years). Patients who died (6.5%) did so after a prolonged course marked by multiple recurrences. Radiotherapy may be of particular benefit to patients whose tumors are not amenable to intact total removal.

Myxopapillary ependymoma. A clinicopathologic and immunocytochemical study of 77 cases.

Soluble and membrane-bound S-100 protein in cerebral cortex synaptosomes. Properties of the S-100 receptor.

— α-Bungarotoxin (α-BuTX) has been used as a marker for studying the acetylcholine receptors (AChRs) in the superior cervical ganglion (SCG) of the adult rat. Binding of [125I]α-BuTX to detergent-solubilized AChRs from rat SCG is a saturable and practically irreversible process. The rate constant of association of the toxin-receptor complex is 1.66 × 105M −1 S−1. The receptor is of nicotinic type. One SCG of adult rat binds about 57 fmol of [125I]α-BuTX corresponding to 9.2 × 105 AChRs per sympathetic neuron. Light microscope autoradiography shows that AChRs are mainly localized along neuronal processes (probably dendrites). The perikarya exhibit a weak radioactive reaction, while the nerve fibres are devoid of AChRs. Following preganglionic denervation the number of AChRs never increases and their spatial distribution seems not to change.

Acetylcholine receptors: number and distribution in intact and deafferented superior cervical ganglion of the rat.

— S-100 protein has been found in the nuclei isolated from the brain cortex of rabbit. The nuclear S-100 constitutes a small portion (0.55 per cent) of the S-100 present in the cytosol. Most of the large and pale nuclei appear to contain much more S-100 than the small and dark ones. The nuclear membrane is permeable in vitro to S-100 in presence of divalent cations. Three forms of S-100 occur in subnuclear fractions: free S-100, present in the soluble protein fraction; labile-bound S-100, present in the deoxyribonucleoprotein fraction and stable-bound S-100, present in the residual or‘nucleolar’fraction. The localization of the S-100 in those regions of the nucleus that are most active in RNA synthesis provides basic information for further studies on the possible role of this protein on genomic expression in nervous tissue.

Nuclear localization of S-100 protein.

— The brain-specific S-100 protein is a neuronal as well as a glial protein. Neuronal S-100 is a migratory protein from soma to terminal of the hypoglossal, vagus and glossopharyngeal nerves of the rabbit (axonal transport of S-100 protein). There is a distinctive rate of flow for S-100 in the somatic and parasympathetic efferent fibres of such cranial nerves.

Nicolo` Miani

Papers

Soluble and membrane-bound S-100 protein in cerebral cortex synaptosomes. Properties of the S-100 receptor.

Acetylcholine receptors: number and distribution in intact and deafferented superior cervical ganglion of the rat.

Nuclear localization of S-100 protein.

Axonal transport of s‐100 protein in mammalian nerve fibres

α-Bungarotoxin-acetylcholine receptors in the chick ciliary ganglion: Effects of deafferentation and axotomy