In vivo genome-wide binding of Id2 to E2F4 target genes as part of a reversible program in mice liver
CELLULAR AND MOLECULAR LIFE SCIENCES
Authors: Ferrer-Vicens, Ivan; Riffo-Campos, Angela L.; Zaragoza, Rosa; Garcia, Concha; Lopez-Rodas, Gerardo; Vina, Juan R.; Torres, Luis; Garcia-Trevijano, Elena R.
Abstract
The inhibitor of differentiation Id2, a protein lacking the basic DNA-binding domain, is involved in the modulation of a number of biological processes. The molecular mechanisms explaining Id2 pleiotropic functions are poorly understood. Id2 and E2F4 are known to bind simultaneously to c-myc promoter. To study whether Id2 plays a global role on transcriptional regulation, we performed in vivo genome-wide ChIP/chip experiments for Id2 and E2F4 in adult mouse liver. An Id2-containing complex was bound to a common sequence downstream from the TSS on a subset of 442 E2F4 target genes mainly related to cell development and chromatin structure. We found a positive correlation between Id2 protein levels and the expression of E2F4/Id2 targets in fetal and adult liver. Id2 protein stability increased in fetal liver by interaction with USP1 de-ubiquitinating enzyme, which was induced during development. In adult liver, USP1 and Id2 levels dramatically decreased. In differentiated liver tissue, when Id2 concentration was low, E2F4/Id2 was bound to the same region as paused Pol II and target genes remained transcriptionally inactive. Conversely, in fetal liver when Id2 levels were increased, Id2 and Pol II were released from gene promoters and target genes up-regulated. During liver regeneration after partial hepatectomy, we obtained the same results as in fetal liver. Our results suggest that Id2 might be part of a reversible development-related program involved in the paused-ON/OFF state of Pol II on selected genes that would remain responsive to specific stimuli.
Effect of Notch1 gene on remyelination in multiple sclerosis in mouse models of acute demyelination
JOURNAL OF CELLULAR BIOCHEMISTRY
Authors: Fan, Hua; Zhao, Jie-Gang; Yan, Jun-Qiang; Du, Gan-Qin; Fu, Qi-Zhi; Shi, Jian; Yang, Yan-Hui; Du, Xiao-Wei; Bai, Xiao-Li
Abstract
This study aims to explore the effects of Notch1 gene on remyelination in multiple sclerosis (MS). A mouse model of acute demyelination was successfully established and the model mice were grouped as cuprizone (CPZ) group, CPZ+small interfering RNA (siRNA)-Notch1 (siNotch1) group, and CPZ+siRNA negative control (NC) group. Meanwhile, another 3 groups (control, control+siNotch1, and control+siRNA NC) were established in normal mice. The changes of weight and maintenance time in rotating drum of mice were observed. Western blot analysis for the protein expressions related to Notch signaling pathway and oligodendrocyte (OL) differentiation in the corpus callosum of the mice. After model establishment, the weight of CPZ-induced demyelinated mice was decreased. During the repair period, the balance ability and movement of the mice was recovered, especially for those injected with siNotch1 plasmid. After model establishment, the number of myelinated axons was decreased. In comparison with the CPZ and CPZ siRNA NC groups, the CPZ+siNotch1 group had a decrease in the number of premature OLs, but increase in mature OLs, and a decrease in oligodendrocyte precursor cells and astrocytes. The expressions of proteins related to Notch signaling pathway, such as HES, Jagged-1 were decreased in the CPZ+siNotch1 group in contrast to the CPZ and CPZ+siRNA groups, but the OL-related transcription factor Sox10 was increased in the CPZ+siNotch1 group than in the CPZ+siRNA NC and CPZ groups, and Id2 was decreased. Our study provided evidence that the inhibition of Notch1 gene could accelerate remyelination in MS.