Project description:Teneurins are large type II transmembrane proteins that are necessary for the normal development of the central nervous system (CNS). While many studies highlight the significance of teneurins, especially during development, there is only limited information known about the molecular mechanisms of function. Previous studies have shown that the N-terminal intracellular domain (ICD) of teneurins can be cleaved at the membrane and subsequently translocates to the nucleus where it can influence gene transcription. Target genes as well as mechanisms have yet to be elucidated, and thus we are investigating the transcriptional activity of the human teneurin-1 ICD in this study. For the whole transcriptome analysis of TEN1-ICD overexpression, we used a modified and improved tet-system. Two separate vectors are required to make the cell line stable. One contains the tet-activating domain fused to a glucocorticoid binding domain (GBD). The other contains the tetO operator sequences directly upstream of a CMV promoter and the gene to be overexpressed. BS149 cells were first transfected with pirtetR-GBD and made stable by Puromycin selection, and then after further transfection with either ptetO-eGFP-His (negative control) or ptetO-TEN1-ICD-eGFP-His by Hygromycin selection. The stable BS149 cell lines were split into three 10 cm Petri dishes each. The triplicate cell lines were cultured once before induction with Dexamethasone and Doxycycline. The overexpressing cells were then FACS-sorted directly into RLT lysis buffer (Qiagen) at a 3:1 volume ratio of lysis buffer to cells in PBS, 24 h post-induction.
Project description:We identified histidine triad nucleotide binding protein 1 (HINT1) as a human teneurin-1 ICD interaction partner in a yeast-2 hybrid screen. This interaction was confirmed in human cells, where HINT1 is known to inhibit the transcription of target genes by directly binding to transcription factors at the promoter. In a whole transcriptome analysis of BS149 glioblastoma cells overexpressing the teneurin-1 ICD, several microphthalmia-associated transcription factor (MITF) target genes were found to be up-regulated. Interestingly, MITF is one of the transcription factors inhibited by HINT1. Thus, we directly compare the transcriptomes of MITF versus TEN1-ICD overexpressing BS149 cells in this study, in order to reveal any co-regulated genes.
Project description:We identified histidine triad nucleotide binding protein 1 (HINT1) as a human teneurin-1 ICD interaction partner in a yeast-2 hybrid screen. This interaction was confirmed in human cells, where HINT1 is known to inhibit the transcription of target genes by directly binding to transcription factors at the promoter. In a whole transcriptome analysis of BS149 glioblastoma cells overexpressing the teneurin-1 ICD, several microphthalmia-associated transcription factor (MITF) target genes were found to be up-regulated. Interestingly, MITF is one of the transcription factors inhibited by HINT1. Thus, we directly compare the transcriptomes of MITF versus TEN1-ICD overexpressing BS149 cells in this study, in order to reveal any co-regulated genes. For the whole transcriptome analysis of MITF, cells were transiently transfected in triplicates with either, pcDNA3.1-RFP-HA (negative control) or pcDNA3.1-MITF-RFP-HA. The overexpressing cells were then FACS-sorted directly into RLT lysis buffer (Qiagen) at a 3:1 volume ratio of lysis buffer to cells in PBS, 24 h post-transfection.
Project description:Specialized telomeric proteins have an essential role in maintaining genome stability through chromosome end protection and telomere length regulation. In the yeast Saccharomyces cerevisiae, the evolutionary conserved CST complex, composed of the Cdc13, Stn1 and Ten1 proteins, largely contributes to these functions. Here, we report the existence of genetic interactions between TEN1 and several genes coding for transcription regulators. Molecular assays confirmed this novel function of Ten1 and further established that it regulates the occupancies of RNA polymerase II and the Spt5 elongation factor within transcribed genes. Since Ten1, but also Cdc13 and Stn1, were found to physically associate with Spt5, we propose that Spt5 represents the target of CST in transcription regulation. Moreover, CST physically associated with Hmo1, previously shown to mediate the architecture of S phase-transcribed genes. The fact that, genome-wide, the promoters of genes down-regulated in the ten1-31 mutant are prefentially bound by Hmo1, leads us to propose a potential role for CST in synchronizing transcription with replication fork progression following head-on collisions. The present finding of the existence of extra-telomeric functions for Ten1 in the regulation of RNA polymerase II in cooperation with Stn1 and Cdc13 has profound repercussions on future studies both on telomeric and transcription pathways.
Project description:Notch signaling is an evolutionarily conserved signal transduction pathway that is essential for metazoan development. At the molecular level, the key components of the Notch pathway are the NOTCH-family receptors, the ligands of the DSL (Delta, Serrate, Lag-2) family and the transcription factor CSL [CBF1/RBPJ, Su(H), Lag-1]. Upon ligand binding, the NOTCH Intra-Cellular Domain (NOTCH ICD) translocates into the nucleus and forms a complex with RBPJ to activate the transcription of target genes. In the absence of NOTCH ICD, RBPJ acts as a transcriptional repressor. Using a proteomic approach, we identified L3MBTL3 as a novel interactor of RBPJ. We discovered that L3MBTL3 competes with NOTCH ICD for binding to RBPJ. In the absence of NOTCH ICD, RBPJ recruits L3MBTL3 and its co-factor KDM1A [lysine (K)-specific demethylase 1A] to the promoters/enhancers of Notch target genes to promote H3K4me2 demethylation and transcriptional repression. In three distinct cell contexts in which Notch signaling governs cell fate, i.e., mature T-cells as well as brain and breast tumor cells, the loss of L3MBTL3 results in the de-repression of Notch target genes. Finally, the genetic analyses of the homologs of RBPJ and L3MBTL3 in Drosophila melanogaster and Caenorhabditis elegans demonstrate that the functional link between RBPJ/Su(H)/lag-1 and L3MBTL3/dL(3)mbt/lin-61 is evolutionarily conserved, thus identifying L3MBTL3 as a universal modulator of Notch signaling in metazoans.
Project description:Teneurins are large type II transmembrane proteins that are necessary for the normal development of the central nervous system (CNS). While many studies highlight the significance of teneurins, especially during development, there is only limited information known about the molecular mechanisms of function. Previous studies have shown that the N-terminal intracellular domain (ICD) of teneurins can be cleaved at the membrane and subsequently translocates to the nucleus where it can influence gene transcription. Target genes as well as mechanisms have yet to be elucidated, and thus we are investigating the transcriptional activity of the human teneurin-1 ICD in this study.