Glial fibrillary acidic protein gene promoter is differently modulated by transforming growth factor-beta 1 in astrocytes from distinct brain regions.
The expression of glial fibrillary acidic protein (GFAP), the major intermediate filament protein of mature astrocytes, is regulated under developmental and pathological conditions. Recently, we have investigated GFAP gene modulation by using a transgenic mouse bearing part of the GFAP gene promoter linked to the beta-galactosidase reporter gene. We demonstrated that cerebral cortex neurons activate the GFAP gene promoter, inducing transforming growth factor-beta 1 (TGF-beta 1) secretion by astrocytes. Here, we report that cortical neurons or conditioned medium derived from them do not activate the GFAP gene promoter of transgenic astrocytes derived from midbrain and cerebellum suggesting a neuroanatomical regional specificity of this phenomenon. Surprisingly, they do induce synthesis of TGF-beta 1 by these cells. Western blot and immunocytochemistry assays revealed wild distribution of TGF receptor in all subpopulations of astrocytes and expression of TGF-beta 1 in neurons derived from all regions, thus indicating that the unresponsiveness of the cerebellar and midbrain GFAP gene to TGF-beta 1 is not due to a defect in TGF-beta 1 signalling. Together, our data highlight the great complexity of neuron-glia interactions and might suggest a distinct mechanism underlying modulation of the GFAP gene in the heterogeneous population of astrocytes throughout the central nervous system.
Sousa
Vivian de Oliveira
Vde O
Departamento de Anatomia, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Centro de Ciências da Saúde, Bloco F, Ilha do Fundão, 21941-590, Rio de Janeiro, RJ, Brazil.
Romão
Luciana
L
Neto
Vivaldo Moura
VM
Gomes
Flávia Carvalho Alcantara
FC
D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D015153:Blotting, Western / Q000379:methods; D001921:Brain / Q000166:cytology* / Q000187:drug effects; D002452:Cell Count / Q000379:methods; D002478:Cells, Cultured; D018920:Coculture Techniques / Q000379:methods; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004622:Embryo, Mammalian; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005346:Fibroblast Growth Factors / Q000494:pharmacology; D005904:Glial Fibrillary Acidic Protein / Q000235:genetics* / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D051379:Mice; D008822:Mice, Transgenic; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000502:physiology*; D053773:Transforming Growth Factor beta1; D014404:Tubulin / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
D017077:Culture Media, Conditioned; D005904:Glial Fibrillary Acidic Protein; C508961:Tgfb1 protein, mouse; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D014404:Tubulin; C462941:beta3 tubulin, mouse; D005346:Fibroblast Growth Factors; D004815:Epidermal Growth Factor; D001616:beta-Galactosidase