title: The unique transcriptional activation domain of nuclear factor-I-X3 is critical to specifically induce marker gene expression in astrocytes.
abstract: Transcription factors of the nuclear factor 1 (NFI) family regulate normal brain development in vertebrates. However, multiple splice variants of four NFI isoforms exist, and their biological functions have yet to be elucidated. Here, we cloned and analyzed human NFI-X3, a novel splice variant of the nfix gene, which contains a unique transcriptional activation (TA) domain completely conserved in primates. In contrast to previously cloned NFI-X1, overexpression of NFI-X3 potently activates NFI reporters, including glial fibrillary acidic protein (GFAP) reporter, in astrocytes and glioma cells. The GAL4 fusion protein containing the TA domain of NFI-X3 strongly activates the GAL4 reporter, whereas the TA domain of NFI-X1 is ineffective. The expression of NFI-X3 is dramatically up-regulated during the differentiation of neural progenitors to astrocytes and precedes the expression of astrocyte markers, such as GFAP and SPARCL1 (Secreted Protein, Acidic and Rich in Cysteines-like 1). Overexpression of NFI-X3 dramatically up-regulates GFAP and SPARCL1 expression in glioma cells, whereas the knockdown of NFI-X3 diminishes the expression of both GFAP and SPARCL1 in astrocytes. Although activation of astrocyte-specific genes involves DNA demethylation and subsequent increase of histone acetylation, NFI-X3 activates GFAP expression, in part, by inducing alterations in the nucleosome architecture that lead to the increased recruitment of RNA polymerase II.
authors.affiliation: Department of Biochemistry, Massey Cancer Center, Virginia Commonwealth University, Richmond, Virginia 23298, USA.
authors.forename: Sandeep K
authors.initials: SK
authors.lastname: Singh
authors.forename: Katarzyna M
authors.initials: KM
authors.lastname: Wilczynska
authors.forename: Adrian
authors.initials: A
authors.lastname: Grzybowski
authors.forename: Jessie
authors.initials: J
authors.lastname: Yester
authors.forename: Bahiya
authors.initials: B
authors.lastname: Osrah
authors.forename: Lauren
authors.initials: L
authors.lastname: Bryan
authors.forename: Sarah
authors.initials: S
authors.lastname: Wright
authors.forename: Irene
authors.initials: I
authors.lastname: Griswold-Prenner
authors.forename: Tomasz
authors.initials: T
authors.lastname: Kordula
mesh_terms: D017398:Alternative Splicing / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D001253:Astrocytes / Q000166:cytology* / Q000502:physiology*; D002135:Calcium-Binding Proteins / Q000235:genetics; D002454:Cell Differentiation / Q000502:physiology; D045744:Cell Line, Tumor; D017124:Conserved Sequence; D053595:Embryonic Stem Cells / Q000166:cytology; D016326:Extracellular Matrix Proteins / Q000235:genetics; D005347:Fibroblasts / Q000166:cytology; D005819:Genetic Markers; D005904:Glial Fibrillary Acidic Protein / Q000235:genetics; D005909:Glioblastoma; D057809:HEK293 Cells; D006801:Humans; D008322:Mammals; D051379:Mice; D008969:Molecular Sequence Data; D051839:NFI Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000502:physiology; D017434:Protein Structure, Tertiary; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation / Q000502:physiology
chemical_list: D002135:Calcium-Binding Proteins; D016326:Extracellular Matrix Proteins; D005819:Genetic Markers; D005904:Glial Fibrillary Acidic Protein; D051839:NFI Transcription Factors; C503126:SPARCL1 protein, human; D012319:RNA Polymerase II