ABSTRACT
Apoptosis is an essential process required for development and morphogenesis in metazoan organisms. The apoptosis pathway and cell death machinery have been extensively studied, but little is known how apoptosis genes are regulated in the course of development . In this study, we analyzed the transcriptional regulation of the pro-apoptotic gene reaper (rpr) by performing whole-mount in situ hybridization in embryos mutant for a number of transcription factor genes in Drosophila melanogaster. In sum, our data show that all factors studied have very specific temporal and spatial effects on rpr transcription . Thus, our results reinforce the concept that apoptosis is an essential process for morphogenesis and that apoptosis related genes very tight developmental factors identified in sculpting the morphology of various embryonic structures by modulating the apoptosis pathway.
Subject(s)
Drosophila Proteins/genetics , Drosophila melanogaster/genetics , Gene Expression Regulation, Developmental , Mutation , Animals , Apoptosis/genetics , Body Patterning/genetics , Drosophila melanogaster/embryology , Embryo, Nonmammalian/embryology , Embryo, Nonmammalian/metabolism , Gene Expression Profiling , Homeodomain Proteins/genetics , In Situ Hybridization/methodsSubject(s)
Adipose Tissue, White/immunology , Atherosclerosis/immunology , CD4-Positive T-Lymphocytes/immunology , Hyperlipidemias/immunology , Inflammation/immunology , Insulin Resistance , 11-beta-Hydroxysteroid Dehydrogenase Type 1/metabolism , Adipokines/metabolism , Adipose Tissue, White/physiopathology , Animals , Atherosclerosis/physiopathology , Blood Glucose/metabolism , Body Weight , Chemokine CCL2/metabolism , Humans , Hydrocortisone/metabolism , Hyperlipidemias/physiopathology , Inflammation/physiopathology , Inflammation Mediators/metabolism , Interferon-gamma/metabolism , Interleukin-6/metabolism , Lipogenesis , Mice , Time Factors , Tumor Necrosis Factor-alpha/metabolismABSTRACT
Hox proteins play fundamental roles in controlling morphogenetic diversity along the anterior-posterior body axis of animals by regulating distinct sets of target genes. Within their rather broad expression domains, individual Hox proteins control cell diversification and pattern formation and consequently target gene expression in a highly localized manner, sometimes even only in a single cell. To achieve this high-regulatory specificity, it has been postulated that Hox proteins co-operate with other transcription factors to activate or repress their target genes in a highly context-specific manner in vivo. However, only a few of these factors have been identified. Here, we analyze the regulation of the cell death gene reaper (rpr) by the Hox protein Deformed (Dfd) and suggest that local activation of rpr expression in the anterior part of the maxillary segment is achieved through a combinatorial interaction of Dfd with at least eight functionally diverse transcriptional regulators on a minimal enhancer. It follows that context-dependent combinations of Hox proteins and other transcription factors on small, modular Hox response elements (HREs) could be responsible for the proper spatio-temporal expression of Hox targets. Thus, a large number of transcription factors are likely to be directly involved in Hox target gene regulation in vivo.
