16 research outputs found
Transcriptional Control of Steroid Biosynthesis Genes in the Drosophila Prothoracic Gland by Ventral Veins Lacking and Knirps.
Specialized endocrine cells produce and release steroid hormones that govern development, metabolism and reproduction. In order to synthesize steroids, all the genes in the biosynthetic pathway must be coordinately turned on in steroidogenic cells. In Drosophila, the steroid producing endocrine cells are located in the prothoracic gland (PG) that releases the steroid hormone ecdysone. The transcriptional regulatory network that specifies the unique PG specific expression pattern of the ecdysone biosynthetic genes remains unknown. Here, we show that two transcription factors, the POU-domain Ventral veins lacking (Vvl) and the nuclear receptor Knirps (Kni), have essential roles in the PG during larval development. Vvl is highly expressed in the PG during embryogenesis and is enriched in the gland during larval development, suggesting that Vvl might function as a master transcriptional regulator in this tissue. Vvl and Kni bind to PG specific cis-regulatory elements that are required for expression of the ecdysone biosynthetic genes. Knock down of either vvl or kni in the PG results in a larval developmental arrest due to failure in ecdysone production. Furthermore, Vvl and Kni are also required for maintenance of TOR/S6K and prothoracicotropic hormone (PTTH) signaling in the PG, two major pathways that control ecdysone biosynthesis and PG cell growth. We also show that the transcriptional regulator, Molting defective (Mld), controls early biosynthetic pathway steps. Our data show that Vvl and Kni directly regulate ecdysone biosynthesis by transcriptional control of biosynthetic gene expression and indirectly by affecting PTTH and TOR/S6K signaling. This provides new insight into the regulatory network of transcription factors involved in the coordinated regulation of steroidogenic cell specific transcription, and identifies a new function of Vvl and Knirps in endocrine cells during post-embryonic development
In malga: indagine in quattro aree delle Alpi Centrali sugli atteggiamenti dei turisti-escursionisti riguardo agli alpeggi
This paper discusses the results of a survey carried out in the summer of 2003 with the aim of gaining a deeper understanding of the attitudes of contemporary tourists towards mountain pastures. 829 visitors were interviewed in four areas in the provinces of Bergamo, Sondrio and Trento using a brief questionnaire. Besides enabling us to gather information about the basic demographic features of the tourist, the questions focused on the motivations for the visit and the attitudes towards specific aspects of pasture land such as landscape, grazing animals and local produce. The tourist profile which emerged from the bivariate analysis ascribed major relevance to the culture and environment associated with mountain pastures rather than the functional meanings. The age of the interviewees was the most significant variable in discriminating the answers: older people tended to appreciate the various different aspects to a greater extent
Purification and characterization of human cell-cell adhesion molecule 1 (C-CAM1) expressed in insect cells
Available online 12 March 2002.The cell-cell adhesion molecule 1 (C-CAM1) plays an important role as a tumor suppressor for prostate cancer. Decreased expression of C-CAM1 was detected in prostate, breast, and colon carcinoma. Reexpression of C-CAM1 in prostate and breast cancer cell lines was able to suppress tumorigenicity in vivo. These observations suggest that C-CAM1 may be used as a marker for cancer detection or diagnosis. To generate monoclonal antibodies specific to C-CAM1, we have overexpressed full-length human C-CAM1 in Sf9 cells using a baculovirus expression system. The protein was purified 104-fold using nickel affinity chromatography. About 0.4 mg purified C-CAM1 was obtained from 200 mg of infected cells. When the purified protein was digested with peptidyl-N-glycosidase, the apparent mobility of the protein on SDS-PAGE changed from 90 to 58 kDa, which is close to the molecular weight predicted from the cloned cDNA sequence. This observation suggests that C-CAM1 was glycosylated on asparagine residues when expressed in Sf9 cells. Western blotting and internal protein sequencing analysis confirmed that the purified protein is human C-CAM1. Biochemical and functional assays indicate that this protein expressed in Sf9 cells displays characteristics similar to those of native protein, including adhesion function and glycosylation modification. Using this protocol, sufficient quantity of this protein can be produced with purity suitable for monoclonal antibody generation and biochemical study.Dillon Phan, Eric Han, Geoff Birrell, Sophie Bonnal, Laura Duggan, Noriko Esumi, Howard Gutstein, Ruixiang Li, Sergiy Lopato, Anita Manogaran, Eleanor S. Pollak, Alo Ray, P.Prabhakara Reddi, Andreas S. Reichert, Paolo Struffi, Gustavo Tiscornia, Laurie Ann Ximenez-Fyvie, Hongbing Zhang and Sue-Hwa Li
The oligomeric state of CtBP determines its role as a transcriptional co-activator and co-repressor of Wingless targets
CtBP has been implicated as both a transcriptional activator and a repressor. Here, in the context of Wingless signalling in Drosophila, it is shown that dimeric CtBP has co-repressor activity, while monomeric CtBP promotes gene expression
The oligomeric state of CtBP determines its role as a transcriptional co-activator and co-repressor of Wingless targets
CtBP has been implicated as both a transcriptional activator and a repressor. Here, in the context of Wingless signalling in Drosophila, it is shown that dimeric CtBP has co-repressor activity, while monomeric CtBP promotes gene expression
Drosophila Ebi mediates Snail-dependent transcriptional repression through HDAC3-induced histone deacetylation
The Drosophila Snail protein is a transcriptional repressor that is necessary for mesoderm formation. Here, we identify the Ebi protein as an essential Snail co-repressor. In ebi mutant embryos, Snail target genes are derepressed in the presumptive mesoderm. Ebi and Snail interact both genetically and physically. We identify a Snail domain that is sufficient for Ebi binding, and which functions independently of another Snail co-repressor, Drosophila CtBP. This Ebi interaction domain is conserved among all insect Snail-related proteins, is a potent repression domain and is required for Snail function in transgenic embryos. In mammalian cells, the Ebi homologue TBL1 is part of the NCoR/SMRT–HDAC3 (histone deacetylase 3) co-repressor complex. We found that Ebi interacts with Drosophila HDAC3, and that HDAC3 knockdown or addition of a HDAC inhibitor impairs Snail-mediated repression in cells. In the early embryo, Ebi is recruited to a Snail target gene in a Snail-dependent manner, which coincides with histone hypoacetylation. Our results demonstrate that Snail requires the combined activities of Ebi and CtBP, and indicate that histone deacetylation is a repression mechanism in early Drosophila development