title: Neuronal differentiation alters the ratio of Sp transcription factors recruited to the CYP46A1 promoter.
abstract: CYP46A1 is a neuron-specific cytochrome P450 that plays a pivotal role in maintaining cholesterol homeostasis in the CNS. However, the molecular mechanisms underlying human CYP46A1 expression are still poorly understood, partly because of the lack of a cellular model that expresses high levels of CYP46A1. Our previous studies demonstrated that specificity protein (Sp) transcription factors control CYP46A1 expression, and are probably responsible for cell-type specificity. Herein, we have differentiated Ntera2/cloneD1 cells into post-mitotic neurons and identified for the first time a human cell model that expresses high levels of CYP46A1 mRNA. Our results show a decrease in Sp1 protein levels, concomitant with the increase in CYP46A1 mRNA levels. This decrease was correlated with changes in the ratio of Sp proteins associated to the CYP46A1 proximal promoter. To examine if the increase in (Sp3+Sp4)/Sp1 ratio was observed in other Sp-regulated promoters, we have selected four genes--reelin, glutamate receptor subunit zeta-1, glutamate receptor subunit epsilon-1 and μ-opioid receptor--known to be expressed in the human brain and analyzed the Sp proteins binding pattern to the promoter of these genes, in undifferentiated and differentiated Ntera2/cloneD1. Our data indicate that the dissociation of Sp1 from promoter regions is a common feature amongst Sp-regulated genes that are up-regulated after neuronal differentiation.
authors: Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL), University of Lisbon, Lisbon, Portugal.
authors: Inês
authors: I
authors: Milagre
authors: Maria João
authors: MJ
authors: Nunes
authors: Margarida
authors: M
authors: Castro-Caldas
authors: Miguel
authors: M
authors: Moutinho
authors: Maria João
authors: MJ
authors: Gama
authors: Elsa
authors: E
authors: Rodrigues
mesh_terms: D002277:Carcinoma / Q000473:pathology; D002352:Carrier Proteins / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D045744:Cell Line, Tumor; D000072556:Cholesterol 24-Hydroxylase; D047369:Chromatin Immunoprecipitation; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D000091042:Reelin Protein; D051703:Sp Transcription Factors / Q000235:genetics / Q000378:metabolism*; D018709:Statistics, Nonparametric; D013250:Steroid Hydroxylases / Q000235:genetics*; D015533:Transcriptional Activation / Q000187:drug effects; D014212:Tretinoin / Q000494:pharmacology
chemical_list: D002352:Carrier Proteins; C485668:GRIN1 protein, human; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D016194:Receptors, N-Methyl-D-Aspartate; D000091042:Reelin Protein; D051703:Sp Transcription Factors; D014212:Tretinoin; D013250:Steroid Hydroxylases; D000072556:Cholesterol 24-Hydroxylase; C000717127:RELN protein, human