scholarly journals Disrupted glial fibrillary acidic protein network in astrocytes from vimentin knockout mice.

1996 ◽  
Vol 133 (4) ◽  
pp. 853-863 ◽  
Author(s):  
M Galou ◽  
E Colucci-Guyon ◽  
D Ensergueix ◽  
J L Ridet ◽  
M Gimenez y Ribotta ◽  
...  
Keyword(s):  
Glial Fibrillary Acidic Protein ◽  
Intermediate Filament ◽  
Network Formation ◽  
Reactive Astrocytes ◽  
Acidic Protein ◽  
Intermediate Filament Protein ◽  
Cultured Astrocytes ◽  
Gfap Expression ◽  
Gfap Immunoreactivity ◽  
Filament Protein

Glial fibrillary acidic protein (GFAP) is an intermediate filament protein expressed predominantly in astrocytes. The study of its expression in the astrocyte lineage during development and in reactive astrocytes has revealed an intricate relationship with the expression of vimentin, another intermediate filament protein widely expressed in embryonic development. these findings suggested that vimentin could be implicated in the organization of the GFAP network. To address this question, we have examined GFAP expression and network formation in the recently generated vimentin knockout (Vim-) mice. We show that the GFAP network is disrupted in astrocytes that normally coexpress vimentin and GFAP, e.g., those of the corpus callosum or the Bergmann glia of cerebellum. Furthermore, Western blot analysis of GFAP protein content in the cerebellum suggests that posttranslational mechanisms are implicated in the disturbance of GFAP network formation. The role of vimentin in this process was further suggested by transfection of Vim-cultured astrocytes with a vimentin cDNA, which resulted in the normal assembly of the GFAP network. Finally, we examined GFAP expression after stab wound-induced astrogliosis. We demonstrate that in Vim- mice, reactive astrocytes that normally express both GFAP and vimentin do not exhibit GFAP immunoreactivity, whereas those that normally express GFAP only retain GFAP immunoreactivity. Taken together, these results show that in astrocytes, where vimentin is normally expressed with GFAP fails to assemble into a filamentous network in the absence of vimentin. In these cells, therefore, vimentin appears necessary to stabilize GFAP filaments and consequently the network formation.

scholarly journals Reexpression of glial fibrillary acidic protein rescues the ability of astrocytoma cells to form processes in response to neurons.

1994 ◽  
Vol 127 (3) ◽  
pp. 813-823 ◽  
Author(s):  
W J Chen ◽  
R K Liem
Keyword(s):  
Glial Fibrillary Acidic Protein ◽  
Intermediate Filament ◽  
Nervous System Development ◽  
Acidic Protein ◽  
Stable Processes ◽  
Intermediate Filament Protein ◽  
Granule Neurons ◽  
Astrocytoma Cells ◽  
Filament Protein ◽  
U251 Cells

Astroglial cells play an important role in orchestrating the migration and positioning of neurons during central nervous system development. Primary astroglia, as well as astrocytoma cells will extend long stable processes when co-cultured with granule neurons. In order to determine the function of the glial fibrillary acidic protein (GFAP), the major intermediate filament protein in astroglia and astrocytoma cells, we suppressed the expression of GFAP by stable transfection of an anti-sense GFAP construct in human astrocytoma U251MG cells. The resulting AS2-U251 cells can no longer extend stable processes in the presence of granule neurons. To show that this effect is due specifically to the absence of GFAP, we reintroduced a fully encoding rat brain GFAP cDNA into these AS2-U251 cells. The resulting rat GFAP appeared as a filamentous network and the reexpression of GFAP rescued the ability of these astrocytoma cells to form stable processes when co-cultured with neurons. From these results, it is clear that the glial specific intermediate filament protein, GFAP, is required for process extension of these astrocytoma cells in response to granule neurons.

scholarly journals Suppression by antisense mRNA demonstrates a requirement for the glial fibrillary acidic protein in the formation of stable astrocytic processes in response to neurons.

1991 ◽  
Vol 112 (6) ◽  
pp. 1205-1213 ◽  
Author(s):  
D E Weinstein ◽  
M L Shelanski ◽  
R K Liem
Keyword(s):  
Glial Fibrillary Acidic Protein ◽  
Cell Lines ◽  
Intermediate Filament ◽  
Neuronal Cell ◽  
Acidic Protein ◽  
Intermediate Filament Protein ◽  
Astrocytoma Cell ◽  
Filament Protein ◽  
U251 Cells

The glial fibrillary acidic protein (GFAP) is a glial-specific intermediate filament protein, which is expressed in astrocytes in the central nervous system, as well as in astrocytoma cell lines. To investigate the function of GFAP, we have studied the human astrocytoma cell line, U251, which constitutively expresses GFAP and vimentin in the same 10-nm filaments. These cells respond to neurons in vitro in the same way as primary astrocytes: they withdraw from the cell cycle, support neuronal cell survival and neurite outgrowth, and they extend complex, GFAP-positive processes. To determine the role of GFAP in these responses, we have specifically suppressed its expression by stably transfecting the U251 cells with an antisense GFAP construct. Two stable antisense cell lines from separate transfections were isolated and were shown to be GFAP negative by Northern and Western blot analyses, and by immunofluorescence studies. The antisense cell lines were inhibited in their ability to extend significant glial processes in response to neurons. In culture with primary neurons, the average increase in process length of the U251 cells was nearly 400%, as compared to only 14% for the antisense transfectants. The other neuron induced responses of astrocytes, i.e., proliferative arrest and neuronal support, were not affected in these cell lines. These data support the conclusion that the glial-specific intermediate filament protein, GFAP, is required for the formation of stable astrocytic processes in response to neurons.

scholarly journals Glial Fibrillary Acidic Protein (GFAP) in Oligodendrogliomas: A Reflection of Transient GFAP Expression by Immature Oligodendroglia

1986 ◽  
Vol 13 (4) ◽  
pp. 307-311 ◽  
Author(s):  
V. Jagadha ◽  
W.C. Halliday ◽  
L.E. Becker
Keyword(s):  
White Matter ◽  
Glial Fibrillary Acidic Protein ◽  
Tumor Cells ◽  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Immunohistochemical Staining ◽  
Neuron Specific Enolase ◽  
Acidic Protein ◽  
Gfap Expression ◽  
S 100

ABSTRACT:Fourteen pure oligodendrogliomas were studied by light- and electronmicroscopy and immunohistochemistry to examine glial fibrillary acidic protein (GFAP) positivity in the tumors. To compare the immunohistochemical staining patterns of neoplastic oligodendroglia and immature oligodendroglia, myelination glia in the white matter of eight normal brains from children under 6 months of age were studied. The tumors possessed light microscopic and ultrastructural features characteristic of oligodendrogliomas. Microtubules were found in the cytoplasm of nine tumors on electronmicroscopy. In one, intermediate filaments and microtubules were observed in occasional tumor cells with polygonal crystalline structures in the cytoplasm. Using the peroxidase-antiperoxidase technique, all specimens were stained for GFAP, vimentin, S-100 and neuron-specific enolase (NSE). In nine tumors, variable numbers of cells with an oligodendroglial morphology reacted positively for GFAP. All tumors were positive for S-100 and negative for vimentin and NSE. The myelination glia in the eight normal brains stained positively for GFAP but not for vimentin. Vimentin is expressed by developing, reactive and neoplastic astrocytes. Thus, GFAP positivity combined with vimentin negativity in both neoplastic and immature oligodendroglia suggests that GFAP positivity in oligodendrogliomas may reflect the transient expression of this intermediate filament by immature oligodendroglia.

scholarly journals The Use of Glial Fibrillary Acidic Protein in First-Tier Assessments of Neurotoxicity

1991 ◽  
Vol 10 (6) ◽  
pp. 719-726 ◽  
Author(s):  
James P. O'Callaghan
Keyword(s):  
Glial Fibrillary Acidic Protein ◽  
Cell Loss ◽  
Acidic Protein ◽  
Intermediate Filament Protein ◽  
Pharmacological Agents ◽  
Cellular Targets ◽  
Dose Time ◽  
Enhanced Expression ◽  
Second Tier ◽  
Filament Protein

Diverse neurotoxic insults result in proliferation and hypertrophy of astrocytes, a subtype of central nervous system glia. The hallmark of this response, often termed “reactive gliosis,” is the enhanced expression of the major intermediate filament protein of astrocytes, glial fibrillary acidic protein (GFAP). These morphological observations suggest that GFAP may be a useful biochemical indicator of neurotoxicity. To investigate this possibility we have administered prototype neurotoxicants to experimental animals and then assessed the effects of these agents on the tissue content of GFAP, as determined by radioimmunoassay. We found that assays of GFAP reveal dose-, time-, and region-dependent patterns of neurotoxicity at toxicant dosages below those that cause light microscopic evidence of cell loss or damage. No false positives have been seen following exposure to a variety of pharmacological agents. By using regional assessments of GFAP in a first-tier evaluation, it should be possible to localize areas of damage. A second-tier evaluation, using assays of proteins or transmitters associated with cells in the affected region, may reveal the cellular targets of neurotoxicity. This two-tiered approach should serve as a foundation for guiding studies aimed at determining mechanisms of neurotoxicity.

scholarly journals Regulation of GFAP Expression

ASN NEURO ◽  
2021 ◽  
Vol 13 ◽  
pp. 175909142098120
Author(s):  
Michael Brenner ◽  
Albee Messing
Keyword(s):  
Transcription Factors ◽  
Histone Methylation ◽  
Intermediate Filament ◽  
Genetic Manipulation ◽  
Direct Interaction ◽  
Intermediate Filament Protein ◽  
Its Gene ◽  
Gfap Expression ◽  
Experimental Findings ◽  
Filament Protein

Expression of the GFAP gene has attracted considerable attention because its onset is a marker for astrocyte development, its upregulation is a marker for reactive gliosis, and its predominance in astrocytes provides a tool for their genetic manipulation. The literature on GFAP regulation is voluminous, as almost any perturbation of development or homeostasis in the CNS will lead to changes in its expression. In this review, we limit our discussion to mechanisms proposed to regulate GFAP synthesis through a direct interaction with its gene or mRNA. Strengths and weaknesses of the supportive experimental findings are described, and suggestions made for additional studies. This review covers 15 transcription factors, DNA and histone methylation, and microRNAs. The complexity involved in regulating the expression of this intermediate filament protein suggests that GFAP function may vary among both astrocyte subtypes and other GFAP-expressing cells, as well as during development and in response to perturbations.

Sign in / Sign up

Export Citation Format

Share Document