Project description:Abstract: Secretion occurs in all cells, with relatively low levels in most cells and extremely high levels in specialized secretory cells, such as those of the pancreas, salivary and mammary glands. Here, we report that the CrebA/Creb3-like family of bZip transcription factors functions to upregulate expression of both the general protein machinery required in all cells for secretion and of cell-type specific secreted proteins. Drosophila CrebA directly binds the enhancers of secretory pathway genes and is both necessary and sufficient to activate expression of every secretory pathway component gene examined thus far. Microarray profiling reveals that CrebA also upregulates expression of genes encoding cell type specific secreted components. Finally, we find that the human CrebA orthologues, Creb3L1 and Creb3L2, have the ability to upregulate the secretory pathway in non-secretory cell types. This SuperSeries is composed of the following subset Series: GSE23334: Active Creb3L1 can upregulate secretory pathway genes in HeLa cells GSE23346: CrebA is a major and direct regulator of secretory pathway gene expression Refer to individual Series
Project description:DNA binding assays, expression analyses, and binding site mutagenesis revealed that the Drosophila CrebA transcription factor (TF) boosts secretory capacity in the embryonic salivary gland (SG) through direct regulation of secretory pathway component genes (SPCGs). The mammalian orthologues of CrebA, the Creb3L-family of leucine zipper TFs, not only activate SPCG expression in a variety of mammalian tissues but can also activate SPCG expression in Drosophila embryos, suggesting a highly conserved role for this family of proteins in boosting secretory capacity. However, in vivo assays reveal that CrebA binds far more genes than it regulates, and it remains unclear what distinguishes functional binding. It is also unclear if CrebA is the major factor driving SPCG gene expression in all Drosophila embryonic tissues and/or if CrebA also regulates other tissue-specific functions. Thus, we did single cell RNA sequencing (scRNA-seq) of wild-type (WT) and CrebA null embryos to explore the relationship between CrebA binding and gene regulation. We find that CrebA binds the proximal promoters of its targets, that SPCGs are the major class of genes regulated by CrebA across tissues, and that CrebA is sufficient to activate SPCG expression even in cells that do not normally express the protein. A comparison of scRNA-Seq to other methods for capturing regulated transcripts reveals that the different methodologies identify overlapping but distinct sets of CrebA targets.
Project description:Abstract: Secretion occurs in all cells, with relatively low levels in most cells and extremely high levels in specialized secretory cells, such as those of the pancreas, salivary and mammary glands. Here, we report that the CrebA/Creb3-like family of bZip transcription factors functions to upregulate expression of both the general protein machinery required in all cells for secretion and of cell-type specific secreted proteins. Drosophila CrebA directly binds the enhancers of secretory pathway genes and is both necessary and sufficient to activate expression of every secretory pathway component gene examined thus far. Microarray profiling reveals that CrebA also upregulates expression of genes encoding cell type specific secreted components. Finally, we find that the human CrebA orthologues, Creb3L1 and Creb3L2, have the ability to upregulate the secretory pathway in non-secretory cell types. Goals: The goals of the microarray experiments were to identify additional targets of the CrebA transcription factor to learn the range of genes regulated by this transcription factor during embryogenesis. Previous work had indicated that CrebA upregulates the protein machinery of the early secretory pathway. Our new data now shows that in addition to the protein machinery, CrebA also upregulates genes encoding the protein cargo that is secreted from specialized secretory organs. RNA was isolated from stage 11-15 wild type Drosophila embryos and compared to RNA from CrebA null mutant embryos of the same age; all samples were hybridized to the Drosophila Genome 2.0 Affymetrix array. Three individual replicates were obtained for each sample.
Project description:Abstract: Secretion occurs in all cells, with relatively low levels in most cells and extremely high levels in specialized secretory cells, such as those of the pancreas, salivary and mammary glands. Here, we report that the CrebA/Creb3-like family of bZip transcription factors functions to upregulate expression of both the general protein machinery required in all cells for secretion and of cell-type specific secreted proteins. Drosophila CrebA directly binds the enhancers of secretory pathway genes and is both necessary and sufficient to activate expression of every secretory pathway component gene examined thus far. Microarray profiling reveals that CrebA also upregulates expression of genes encoding cell type specific secreted components. Finally, we find that the human CrebA orthologues, Creb3L1 and Creb3L2, have the ability to upregulate the secretory pathway in non-secretory cell types. Goals: Creb3L1 is the closest related human orthologue of Drosophila CrebA. CrebA is required to upregulate genes encoding the protein machinery and cargo in specialized secretory cells. To determine if the human orthologues of CrebA, Creb3L1 and Creb3L2, perform the same function, we expressed the truncated active form of Creb3L1 in non-secretory HeLa cells. We then performed microarray experiments and found that active Creb3L1 is sufficient to upregulate genes encoding the protein machinery of the secretory pathway, as observed with Drosophila CrebA. HeLa cells were transiently co-transfected with truncated Creb3L1 (Creb3L1 T) and GFP. Following 20 hours in culture, GFP positive cells were isolated by FACS and RNA was extracted using the Rneasy kit (Qiagen). As a control, mock transfected cells were also subjected to cell sorting and RNA was extracted using the same protocols. At least three replicates were obtained for each group.
Project description:Abstract: Secretion occurs in all cells, with relatively low levels in most cells and extremely high levels in specialized secretory cells, such as those of the pancreas, salivary and mammary glands. Here, we report that the CrebA/Creb3-like family of bZip transcription factors functions to upregulate expression of both the general protein machinery required in all cells for secretion and of cell-type specific secreted proteins. Drosophila CrebA directly binds the enhancers of secretory pathway genes and is both necessary and sufficient to activate expression of every secretory pathway component gene examined thus far. Microarray profiling reveals that CrebA also upregulates expression of genes encoding cell type specific secreted components. Finally, we find that the human CrebA orthologues, Creb3L1 and Creb3L2, have the ability to upregulate the secretory pathway in non-secretory cell types. Goals: Creb3L1 is the closest related human orthologue of Drosophila CrebA. CrebA is required to upregulate genes encoding the protein machinery and cargo in specialized secretory cells. To determine if the human orthologues of CrebA, Creb3L1 and Creb3L2, perform the same function, we expressed the truncated active form of Creb3L1 in non-secretory HeLa cells. We then performed microarray experiments and found that active Creb3L1 is sufficient to upregulate genes encoding the protein machinery of the secretory pathway, as observed with Drosophila CrebA.
Project description:Abstract: Secretion occurs in all cells, with relatively low levels in most cells and extremely high levels in specialized secretory cells, such as those of the pancreas, salivary and mammary glands. Here, we report that the CrebA/Creb3-like family of bZip transcription factors functions to upregulate expression of both the general protein machinery required in all cells for secretion and of cell-type specific secreted proteins. Drosophila CrebA directly binds the enhancers of secretory pathway genes and is both necessary and sufficient to activate expression of every secretory pathway component gene examined thus far. Microarray profiling reveals that CrebA also upregulates expression of genes encoding cell type specific secreted components. Finally, we find that the human CrebA orthologues, Creb3L1 and Creb3L2, have the ability to upregulate the secretory pathway in non-secretory cell types. Goals: The goals of the microarray experiments were to identify additional targets of the CrebA transcription factor to learn the range of genes regulated by this transcription factor during embryogenesis. Previous work had indicated that CrebA upregulates the protein machinery of the early secretory pathway. Our new data now shows that in addition to the protein machinery, CrebA also upregulates genes encoding the protein cargo that is secreted from specialized secretory organs.
Project description:Abstract: Secretion occurs in all cells, with relatively low levels in most cells and extremely high levels in specialized secretory cells, such as those of the pancreas, salivary and mammary glands. Here, we report that the CrebA/Creb3-like family of bZip transcription factors functions to upregulate expression of both the general protein machinery required in all cells for secretion and of cell-type specific secreted proteins. Drosophila CrebA directly binds the enhancers of secretory pathway genes and is both necessary and sufficient to activate expression of every secretory pathway component gene examined thus far. Microarray profiling reveals that CrebA also upregulates expression of genes encoding cell type specific secreted components. Finally, we find that the human CrebA orthologues, Creb3L1 and Creb3L2, have the ability to upregulate the secretory pathway in non-secretory cell types. This SuperSeries is composed of the SubSeries listed below.
Project description:Salivary gland-specific binding assays reveal that CrebA, a bZIP transcription factor, directly binds the vast majority of genes encoding the secretory machinery, including proteins of the signal recognition particle and receptor, proteins involved in co-translational import of cargo into the ER, proteins involved in vesicular transport between the ER and Golgi, as well as the structural proteins and enzymes of these organelles. CrebA does not bind salivary gland-specific cargo genes. Instead, it binds and boosts expression of Sage, which encodes a bHLH transcription factor that upregulates cargo expression. CrebA also directly binds and upregulates Xbp1, which encodes a key factor in the unfolded protein response, and Tudor-SN, which encodes a protein that in other systems increases secretory cargo mRNA levels.
Project description:Dendrite aberration is a common feature of neurodegenerative diseases caused by protein toxicity, but the underlying mechanisms remain largely elusive. Here, we show that nuclear polyglutamine (polyQ) toxicity resulted in defective terminal dendrite elongation accompanied with a loss of Golgi outposts (GOPs) and decreased supply of plasma membrane (PM) in Drosophila Class IV da (C4da) neurons. mRNA sequencing revealed that down-regulated genes by polyQ proteins included many secretory pathway-related genes, including COPII genes regulating GOP synthesis. Transcription factor enrichment analysis identified CREB3L1/CrebA, which regulates COPII gene expression. CrebA overexpression in C4da neurons restored the dysregulation of COPII genes, GOP synthesis, and PM supply. The ChIP-PCR assay revealed that CrebA expression was regulated by CBP, which was sequestered by polyQ proteins. Furthermore, co-overexpression of CrebA and Rac1 synergistically restored the polyQ-induced dendrite pathology. Collectively, our results suggest that GOPs impaired by polyQ proteins contribute to dendrite pathology through the CBP-CrebA-COPII pathway.