ABSTRACT
Little is known about the functions of downstream regulatory element antagonist modulator (DREAM) in embryonic stem cells (ESCs). However, DREAM interacts with cAMP response element-binding protein (CREB) in a Ca(2+)-dependent manner, preventing CREB binding protein (CBP) recruitment. Furthermore, CREB and CBP are involved in maintaining ESC self-renewal and pluripotency. However, a previous knockout study revealed the protective function of DREAM depletion in brain aging degeneration and that aging is accompanied by a progressive decline in stem cells (SCs) function. Interestingly, we found that DREAM is expressed in different cell types, including human ESCs (hESCs), human adipose-derived stromal cells (hASCs), human bone marrow-derived stromal cells (hBMSCs), and human newborn foreskin fibroblasts (hFFs), and that transitory inhibition of DREAM in hESCs reduces their pluripotency, increasing differentiation. We stipulate that these changes are partly mediated by increased CREB transcriptional activity. Overall, our data indicates that DREAM acts in the regulation of hESC pluripotency and could be a target to promote or prevent differentiation in embryonic cells.
Subject(s)
Human Embryonic Stem Cells/metabolism , Kv Channel-Interacting Proteins/metabolism , Adipose Tissue/cytology , Antigens, Surface/metabolism , CREB-Binding Protein/genetics , CREB-Binding Protein/metabolism , Cell Differentiation , Cells, Cultured , Cyclic AMP Response Element-Binding Protein/genetics , Cyclic AMP Response Element-Binding Protein/metabolism , Down-Regulation , Fibroblasts/cytology , Fibroblasts/metabolism , Human Embryonic Stem Cells/cytology , Humans , Kv Channel-Interacting Proteins/antagonists & inhibitors , Kv Channel-Interacting Proteins/genetics , Proteoglycans/metabolism , RNA Interference , RNA, Small Interfering/metabolism , Real-Time Polymerase Chain Reaction , Stage-Specific Embryonic Antigens/metabolism , Stromal Cells/cytology , Stromal Cells/metabolismABSTRACT
N-ethyl-N-nitrosurea (ENU), a type of N-nitrous compound (NOC), has been used as inductor for brain tumours due to its mutagenic effect on the rodent embryo. ENU also affected adult neurogenesis when administered during pregnancy. However, no studies have investigated the effect of ENU when exposured during adulthood. For this purpose, three experimental groups of adult mice were injected with ENU at different doses and killed shortly after exposure. When administered in adult mice, ENU did not form brain tumours but led to a disruption of the subventricular zone (SVZ), an adult neurogenic region. Analyses of the samples revealed a reduction in the numbers of neural progenitors compared with control animals, and morphological changes in ependymal cells. A significant decrease in proliferation was tested in vivo with 5-bromo-2-deoxyuridine administration and confirmed in vitro with a neurosphere assay. Cell death, assessed as active-caspase-3 reactivity, was more prominent in treated animals and cell death-related populations increased in parallel. Two additional groups were maintained for 45 and 120 days after five doses of ENU to study the potential regeneration of the SVZ, but only partial recovery was detected. In conclusion, exposure to ENU alters the organization of the SVZ and causes partial exhaustion of the neurogenic niche. The functional repercussion of these changes remains unknown, but exposure to NOCs implies a potential risk that needs further evaluation.
