title: Discovery of transcriptional programs in cerebral ischemia by in silico promoter analysis.
abstract: In stroke, gene transcription plays a central role in processes such as neuroinflammation and neuroregeneration. To predict new transcriptional regulatory mechanisms in cerebral ischemia, we applied a computational approach combining two kinds of information: the results of a microarray analysis in a mouse model of stroke and in silico detection of transcription factor (TF) binding sites in promoter regions of the genes on the array. By using a discriminative logistic regression model, we identified binding sites significantly associated with the up-regulation of genes. Out of 356 TF binding sites defined in TRANSFAC, we could link 32 to gene up-regulation in cerebral ischemia. These sites bind both TFs with an established and a so far unknown role in cerebral ischemia. To evaluate the results further we investigated whether two TFs, CCAAT/enhancer binding protein beta (C/EBP beta) and vitamin D receptor (VDR), are activated as predicted. Immunohistochemistry demonstrated that C/EBP beta and VDR translocated to the nucleus in cerebral ischemia. Chromatin immunoprecipitation revealed increased binding of C/EBP beta to the promoter of its target gene saa3. In addition, we found evidence for the up-regulation of VDR in brain samples from human stroke patients. These results confirm the activation of C/EBP beta and VDR in cerebral ischemia. Thus, our in silico analysis may provide additional information on transcriptional regulation in stroke and suggests several novel transcriptional programs for further exploration.
authors.affiliation: Department of Pharmacology, University of Heidelberg, Germany.
authors.forename: Dirk A
authors.initials: DA
authors.lastname: Ridder
authors.forename: Svetlana
authors.initials: S
authors.lastname: Bulashevska
authors.forename: Ganta Vijay
authors.initials: GV
authors.lastname: Chaitanya
authors.forename: Phanithi Prakash
authors.initials: PP
authors.lastname: Babu
authors.forename: Benedikt
authors.initials: B
authors.lastname: Brors
authors.forename: Roland
authors.initials: R
authors.lastname: Eils
authors.forename: Armin
authors.initials: A
authors.lastname: Schneider
authors.forename: Markus
authors.initials: M
authors.lastname: Schwaninger