Glial fibrillary acidic protein and Alzheimer's disease

A major protein associated with Alzheimer's disease (AD) was detected by an electrophoretic study of temporal cortex obtained at autopsy from patients affected with AD, non-AD dementia, and normal controls matched for age and sex. A markedly increased amount of a 50,000 dalton molecular weight protein, which has been identified as glial fibrillary acidic protein (GFAP), was observed in the crude nuclear fraction of temporal cortex from AD patients. These electrophoretic data may reflect the presence of GFAP immunopositive astrocytic processes that have been shown by immunocytologic methods to infiltrate the neurofibrillary tangles that characterize AD.Some aspects of this work have been published as an abstract in 1983, Fed. Proc. 42:2009.     

Glial fibrillary acidic protein and desmin in salivary neoplasms

The presence of intermediate filament proteins (IFP) in normal salivary gland tissue and in a number of salivary gland neoplasms has been investigated by immunohistochemical techniques on frozen sections. Cytokeratins (CKs) were seen in almost all normal epithelial cells. In the parotid gland and in palatal gland tissue, a co-expression of cytokeratin and glial fibrillary acidic protein (GFAP) was seen in some myoepithelial cells, but this was not apparent in the submandibular gland. In some pleomorphic adenomas, carcinomas in pleomorphic adenomas, one mucoepidermoid carcinoma, one mucus-producing adenopapillary carcinoma and one adenoid cystic carcinoma, cells expressing three different IFP classes were found (CKs, vimentin, GFAP). These cells were most often situated peripherally in the tumour cords or ducts. The cytokeratin pattern in these cells, as revealed by mAbs PKK1-3, was similar to that in normal myoepithelial cells. Furthermore, reactivity for a fourth class of IFP, desmin, could be seen in this cell type in two carcinomas in pleomorphic adenomas, and also in a few cells in a pleomorphic adenoma and an adenoid cystic carcinoma. Thus the pattern of IFP expression in salivary gland neoplasms, is very complex, and cannot always be related to the normal tissue.     

Glial fibrillary acidic protein is localized in the lens epithelium

The epithelium of the mouse lens stains intensely with antisera to glial fibrillary acidic protein (GFAP). A protein co-migrating with GFAP and immunoreactive with antisera to GFAP can be demonstrated in lens epithelium protein extracts by immunoblots. GFAP has previously been considered unique to cells of neural origin, but this study demonstrates that ectodermally derived cells express GFAP or a highly similar protein.     

Expression of vimentin and glial fibrillary acidic protein in human developing spinal cord

Summary Expression of intermediate filament proteins was studied in human developing spinal cord using immunoperoxidase and double-label immunofluorescence methods with monoclonal antibodies to vimentin and glial fibrillary acidic protein (GFAP). Vimentin was found in the processes of radial glial cells in 6-week embryos, while GFAP appeared in vimentin-positive astroglial cells at 8–10 weeks. GFAP and vimentin were present in approximately equal amounts in differentiating astrocytes in 23-week spinal cord. In 30-week fetuses, astrocytes reacted strongly for GFAP, while both the reaction intensity and the number of vimentin-positive cells fluctuated predominantly in the grey matter. No clear-cut transition from vimentin to GFAP was noticed during the development of astrocytes. The majority of ependymal cells in 23-week fetuses contained vimentin but only a few of them reacted for GFAP. The expression of vimentin continued during the whole development of the ependymal layer, in contrast to the reactivity for GFAP which disappeared between the 30th week and term.     

Glial fibrillary acidic protein in the brain of prenatally stressed rats

The content of glial fibrillary acidic protein (GFAP) was studied in the brain structures of rats borne by intact females and females that underwent stress. In the offspring of stressed rats, the GFAP content in the brain gray and white matter on the 15th postnatal day noticeably dropped. On the 30th postnatal day, the GFAP content in the cortex and pons increased, while it somewhat decreased in the striatum and cerebellum. The results suggest that formation of the intermediate astrocyte filaments in the animals subjected to prenatal stress is markedly disturbed.     

Glial fibrillary acidic protein and differentiation of neonatal rat pituicytes in vitro

Summary The appearance and intracellular localisation of glial fibrillary acidic protein (GFAP) in pituicytes in neural lobe cultures of newborn rats aged 7 to 30 days were investigated by use of the indirect immunofluorescence method. GFAP-immunoreactive cells were observed mostly in the outgrowth zone. GFAP was localised in the perikaryal cytoplasm as well as in pituicyte processes. GFAP-positive pituicytes showed considerable morphological polymorphism. The presence of GFAP — astrocytic marker — in pituicytes in vitro and the evident morphological similarity to cultured astrocytes suggest the astroglial character of these cells.     

Glial fibrillary acidic protein is greatly modified by oxidative stress in aceruloplasminemia brain

Aceruloplasminemia is an autosomal recessive disorder of iron metabolism caused by mutations in the ceruloplasmin (Cp) gene. The neuropathological hallmark of this disease is intracellular iron overload, which is thought to lead to neuronal cell death through increased oxidative stress. We evaluated and characterized protein oxidation in the brain of a patient with this disease. The protein carbonyl content in the cerebral cortex of the patient was elevated compared to controls. Furthermore, peptide mass fingerprinting and partial amino acid sequencing identified glial fibrillary acidic protein (GFAP) as the major carbonylated protein in the cerebral cortex of the patient. In conjunction with the facts that Cp mainly localizes to astrocytes in the central nervous system and that astrocytes are loaded with much more iron than neurons in the cerebral cortex, our findings indicate that Cp deficiency may primarily damage astrocytes. We speculate that the dysfunction of astrocytes may be causatively related to neuronal cell loss in aceruloplasminemia.     

Glial fibrillary acidic protein from bovin and rat brain Degradation in tissues and homogenates

Compared with human material glial fibrillary acidic protein isolated from bovine, rat and mouse brain was remarkably homogeneous and migrated as a single band at 54 000 mol. wt. on sodium dodecyl sulfate gel electrophoresis. The protein was extremely susceptible to proteolysis and lower molecular weight components were invariably isolated together with the major species when the brain was not rapidly frozen. Further degradation of the 54 000 mol. wt. polypeptide in bovine tissues incubated at 24 °C resulted in preparations essentially identical to those previously isolated from human autopsy material and separating into a series of immunologically active polypeptides ranging in molecular weight from 54 000 to approximately 40 500. The gel band pattern obtained after progressively longer periods of autolysis suggested that small fragments were cleaved from the original polypeptide in successive steps of degradation. As in human brain, the lower molecular weight products in the 45 000–40 500 range were more resistant to proteolysis and still present after prolonged periods of tissue autolysis. The effect of the pH and of proteinase inhibitors on degradation was studied in homogenates of bovine brain stem incubated at 37 °C. At pH 8.0 proteolysis of the glial fibrillary acidic protein followed essentially the same pattern as in tissue. Cleavage of the major species was not prevented by the addition of proteinase inhibitors. At pH 6.0 and 6.5 a different type of degradation was observed, with rapid breakdown of the protein and loss of immunological activity. Increased solubility in buffer solutions was another effect of autolysis. Compared with cerebral cortex and brain stem, where most of the protein was water soluble, only a small fraction was extracted with buffer from bovine white matter. However, the solubility markedly increased following incubation and comparable amounts were extracted in buffer and in 6 M urea.     

Glial fibrillary acidic protein (GFAP)-like immunoreactivity in rat endocrine pancreas.

The study of intermediate filament expression in the pancreatic epithelium has been previously focused almost exclusively on cytokeratins. Transient vimentin immunoreactivity has also been detected in duct cells of rat fetal pancreas. Here we report that, in rat pancreas, intense GFAP-like immunoreactivity is detectable in a subpopulation of endocrine cells located in the periphery of the islet of Langerhans. In addition, staining appeared to be preferentially localized to the apical pole of the cells. Two different polyclonal antibodies were employed in this study, with analogous results. Staining of consecutive sections with anti-GFAP, anti-glucagon, and anti-somatostatin antibodies demonstrates that GFAP-like immunoreactivity is present in glucagon-secreting cells. The relevance of this finding is discussed. (J Histochem Cytochem 48:259-265, 2000)     

Ependyma: phylogenetic evolution of glial fibrillary acidic protein (GFAP) and vimentin expression in vertebrate spinal cord

The phylogenetic evolution was studied of both glial fibrillary acidic protein (GFAP) and vimentin expression in the ependyma of the adult vertebrate spinal cord. Eleven species from different vertebrate groups were examined using different fixatives and fixation procedures to demonstrate any differences in immunoreactivity. GFAP expression in the ependymal cells showed a clear inverse relation with phylogenetic evolution because it was more elevated in lower than in higher vertebrates. GFAP positive cells can be ependymocytes and tanycytes, although depending on their structural characteristics and distribution, the scarce GFAP positive ependymal cells in higher vertebrates may be tanycytes. Ependymal vimentin expression showed a species-dependent pattern instead of a phylogenetic pattern of expression. Vimentin positive ependymal cells were only found in fish and rats; in fish, they were tanycytes and were quite scarce, with only one or two cells per section being immunostained. However, in the rat spinal cord, all the ependymocytes showed positive immunostaining for vimentin. The importance of the immunohistochemical procedure, the cellular nature of GFAP positive ependymal cells and the relationship between tanycytes and ependymocytes are discussed, as well as GFAP and vimentin expression.     

Immunoblot identification of glial fibrillary acidic protein in rat sciatic nerve,brain, and spinal cord during development

The appearance of the glial fibrillary acidic protein (GFAP) during embryonic and postnatal development of the rat brain and spinal cord and in rat sciatic nerve during postnatal development was examined by the immunoblot technique. Cytoskeletal proteins were isolated from the central and peripheral nervous system and separated by SDS slab gel electrophoresis or two-dimensional gel electrophoresis. Proteins from the acrylamide gels were transferred to nitrocellulose sheets which were treated with anti-bovine GFAP serum and GFAP was identified by the immunoblot technique. GFAP was present in the embryonic rat brain and spinal cord at 14 and 16 days of gestation respectively. The appearance of GFAP at this stage of neural development suggests that the synthesis of GFAP may be related to the proliferation of radial glial cells from which astrocytes are derived. It is also feasible that GFAP provides structural support for the radial glial cell processes analogous to its role in differentiated astrocytes. GFAP was found to be present in rat sciatic nerves at birth and at all subsequent stages of development. These results indicate that some cellular elements in the rat sciatic nerve, such as Schwann cells, are capable of synthesizing GFAP which is immunochemically indistinguishable from its counterpart in the central nervous system. Thus it appears that GFAP is present both in the central and peripheral nervous system of the rat when the glial cells synthesizing GFAP are still undergoing differentiation.     

Modulation of NADPH-diaphorase and glial fibrillary acidic protein by progesterone in astrocytes from normal and injured rat spinal cord

Progesterone (P4) can be synthesized in both central and peripheral nervous system (PNS) and exerts trophic effects in the PNS. To study its potential effects in the spinal cord, we investigated P4 modulation (4 mg/kg/day for 3 days) of two proteins responding to injury: NADPH-diaphorase, an enzyme with nitric oxide synthase activity, and glial fibrillary acidic protein (GFAP), a marker of astrocyte reactivity. The proteins were studied at three levels of the spinal cord from rats with total transection (TRX) at T10: above (T5 level), below (L1 level) and caudal to the lesion (L3 level). Equivalent regions were dissected in controls. The number and area of NADPH-diaphorase active or GFAP immunoreactive astrocytes/0.1 mm(2) in white matter (lateral funiculus) or gray matter (Lamina IX) was measured by computerized image analysis. In controls, P4 increased the number of GFAP-immunoreactive astrocytes in gray and white matter at all levels of the spinal cord, while astrocyte area also increased in white matter throughout and in gray matter at the T5 region. In control rats P4 did not change NADPH-diaphorase activity. In rats with TRX and not receiving hormone, a general up-regulation of the number and area of GFAP-positive astrocytes was found at all levels of the spinal cord. In rats with TRX, P4 did not change the already high GFAP-expression. In the TRX group, instead, P4 increased the number and area of NADPH-diaphorase active astrocytes in white and gray matter immediately above and below, but not caudal to the lesion. Thus, the response of the two proteins to P4 was conditioned by environmental factors, in that NADPH-diaphorase activity was hormonally modulated in astrocytes reacting to trauma, whereas up-regulation of GFAP by P4 was produced in resting astrocytes from non-injured animals.     

Developmental expression of the Glial fibrillary acidic protein (GFAP) gene in the mouse retina

1. In the nervous system, Glial fibrillary acidic protein (GFAP) is a well-known, cell type-specific marker for astrocytes. 2. In the mammalian retina, Muller cells, the major class of retinal glia, do not express GFAP or contain only low amounts of this protein. In retinas with photoreceptor degeneration, however, high levels of GFAP are found. It is possible that GFAP synthesis in these retinas could result from "dedifferentiation" of Muller cells as a consequence of disruption of normal neuron-glia interactions. 3. We have carried out immunocytochemical and in situ hybridization studies to examine whether GFAP or its mRNA is expressed by retinal cells early in embryonic development. 4. Our results show that GFAP-containing cells, which are probably astrocytes, are found only in the ganglion cell and nerve fiber layers and that these cells appear after postnatal day-1 (P-1) and continue to form until P-10. 5. Astrocyte formation starts from the optic disc and moves toward the periphery of the retina at a rate of approximately 160-200 microns per day. 6. An unexpected result from these studies is that GFAP mRNA levels are high in the first week of birth and decline rapidly as the animal develops. 7. Finally, we did not find either GFAP or GFAP mRNA in retinal cells other than astrocytes during normal development.     

Glial fibrillary acidic protein is a major target of glycoxidative and lipoxidative damage in Pick's disease

Pick's disease is a subset of fronto-temporal dementia characterised by severe atrophy of the temporal and frontal lobes due to marked neuronal loss accompanied by astrocytic gliosis enriched in glial acidic protein. The remaining neurones have intracytoplasmic inclusions composed of hyperphosphorylated tau, called Pick bodies, in addition to hyperphosphorylated tau in astrocytes and oligodendrocytes. Gel electrophoresis and western blotting using markers of glycoxidation (advanced glycation end products, N-carboxyethyl-lysine and N-carboxymethyl-lysine: AGE, CEL, CML, respectively) and lipoxidation (4-hydroxy-2-nonenal: HNE, and malondialdehyde-lysine: MDAL) were used in the frontal and occipital cortex in three Pick's disease cases and three age-matched controls. In Pick's disease, increased AGE, CML, CEL, HNE and MDAL bands of about 50 kDa were observed in the frontal cortex (but not in the occipital cortex) in association with increased density of glial acidic protein bands. Bi-dimensional gel electrophoresis and western blotting also disclosed increased amounts and numbers of glial acidic protein isoforms in the frontal cortex in Pick's disease. Moreover, redox proteomics showed glycoxidation, as revealed with anti-CEL antibodies and lipoxidation using anti-HNE antibodies, of at least three glial acidic protein isoforms. The present results demonstrate that glial acidic protein is a target of oxidative damage in the frontal cortex in Pick's disease.     

Glial fibrillary acidic protein (GFAP) shows circadian oscillations in crayfish Procambarus clarkii putative pacemakers

Although several studies of glia have examined glial fibrillary acid protein (GFAP) and its relationship to the circadian rhythms of different organisms, they have not explored the daily GFAP oscillations in the putative pacemakers of the crayfish Procambarus clarkii or in other crustaceans. In this study we investigated the daily variations in GFAP concentrations in the eyestalk and brain, which are considered to be putative pacemakers in adult P. clarkii. In both structures, the glial GFAP was quantified using the indirect enzyme-linked immunosorbent assay (ELISA), and double labeling immunofluorescence was used to detect it and its co-localization with protein Period (PER), an important component of the circadian clock, in various regions of both structures. The ELISA results were analyzed using Cosinor and one-way ANOVA with Bonferroni and Scheffé’s post hoc tests. The results of this analysis showed that the GFAP levels present circadian oscillations in both structures. Moreover, GFAP was localized in different structures of the eyestalk and brain; however, co-localization with PER occurred only in the lamina ganglionaris, specifically in the cartridges of the eyestalk and in some of the cluster 9 brain cells. These results suggest that as in other invertebrates and vertebrates, glial cells could be involved in the circadian system of P. clarkii; however, thus far we cannot know whether the glial cells are only effectors, participate in afferent pathways, or are part of the circadian clock.     

Glial fibrillary acidic protein from bovine and rat brain. Degradation in tissues and homogenates.

Compared with human material glial fibrillary acidic protein isolated from bovine, rat and mouse brain was remarkably homogeneous and migrated as a single band at 54 000 mol. wt. on sodium dodecyl sulfate gel electrophoresis. The protein was extremely susceptible to proteolysis and lower molecular weight components were invariably isolated together with the major species when the brain was not rapidly frozen. Further degradation of the 54 000 mol wt. polypeptide in bovine tissues incubated at 24 degrees C resulted in preparations essentially identical to those previously isolated from human autopsy material and separating into a series of immunologically active polypeptides ranging in molecular weight from 54 000 to approximately 40 500. The gel band pattern obtained after progressively longer periods of autolysis suggested that small fragments were cleaved from the original polypeptide in successive steps of degradation. As in human brain, the lower molecular weight products in the 45 000-40 500 range were more resistant to proteolysis and still present after prolonged periods of tissue autolysis. The effect of the pH and of proteinase inhibitors on degradation was studied in homogenates of bovine brain stem incubated at 37 degrees C. At pH 8.0 PROTEOLYSIS OF The glial fibrillary acidic protein followed essentially the same pattern as in tissue. Cleavage of the major species was not prevented by the addition of proteinase inhibitors. At pH 6.0 and 6.5 a different type of degradation was observed, with rapid breakdown of the protein and loss of immunological activity. Increased solubility in buffer solutions was another effect of autolysis. Compared with cerebral cortex and brain stem, where most of the protein was water soluble, only a small fraction was extracted with buffer from bovine white matter. However, the solubility markedly increased following incubation and comparable amounts were extracted in buffer and in 6 M urea.     

Glial fibrillary acidic protein-like immunoreactivity in cat satellite cells of sympathetic ganglia

The presence and distribution of glial fibrillary acidic protein (GFAP), an astrocytic marker protein associated with glial filaments in the sympathetic ganglia of adult cats, was investigated immunocytochemically. This study revealed GFAP plus cells throughout the ganglion. Immunopositive cells surround nerve cell bodies and separate them from the blood vessels.