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The Drosophila compound eye is formed by selective recruitment of undifferentiated cells into clusters called ommatidia during late larval and early pupal development. Ommatidia at the edge of the eye, which often lack the full complement of photoreceptors and support cells, undergo apoptosis during mid-pupation. We have found that this cell death is(More)
neurotransmitter γ-aminobutyric acid (GABA), the multipolar cell, were on average three times the size of Ca 2+ transients in terminals apposed to another class of GABAergic interneuron, the bitufted cell. Pyramidal cell boutons apposed to other pyramidal cells displayed the full 10-fold range in amplitude of the Ca 2+ transient. What are the consequences(More)
This paper reports the isolation and characterization of Chinese hamster ovary cell mutants defective in low density lipoprotein (LDL)-cholesterol trafficking. The parental cell line was 25-RA, which possesses LDL receptors and various cholesterogenic enzyme activities that are partially resistant to down regulation by exogenous sterols (Chang, T. Y., and(More)
Specific recognition of DNA by transcription factors is essential for precise gene regulation. In Wingless (Wg) signaling in Drosophila, target gene regulation is controlled by T cell factor (TCF), which binds to specific DNA sequences through a high mobility group (HMG) domain. However, there is considerable variability in TCF binding sites, raising the(More)
will break the barrier, making the TJ a frequent contributor to a vast range of pathologies of blood vessels and epithelial organs. Since most of these insults have pleotropic cellular effects, it is difficult to envision therapies that could target specific TJ components or functions. In contrast, some assaults on the barrier are quite specific. For(More)
Regulation of gene expression by signaling pathways often occurs through a transcriptional switch, where the transcription factor responsible for signal-dependent gene activation represses the same targets in the absence of signaling. T-cell factors (TCFs) are transcription factors in the Wnt/ß-catenin pathway, which control numerous cell fate specification(More)
The T-cell factor (TCF) family of transcription factors are major mediators of Wnt/β-catenin signaling in metazoans. All TCFs contain a High Mobility Group (HMG) domain that possesses specific DNA binding activity. In addition, many TCFs contain a second DNA binding domain, the C-clamp, which binds to DNA motifs referred to as Helper sites. While HMG and(More)
The Wnt/β-catenin signaling pathway plays many important roles in animal development, tissue homeostasis and human disease. Transcription factors of the TCF family mediate many Wnt transcriptional responses, promoting signal-dependent activation or repression of target gene expression. The mechanism of this specificity is poorly understood. Previously, we(More)
The evolutionarily conserved Wnt/ß-catenin (Wnt/ß-cat) pathway plays an important role in animal development in metazoans. Many Wnt targets are regulated by members of the TCF/LEF1 (TCF) family of transcription factors. All TCFs contain a High Mobility Group (HMG) domain that bind specific DNA sequences. Invertebrate TCFs and some vertebrate TCF isoforms(More)
Intestinal stem cell (ISC) self-renewal and proliferation are directed by Wnt/β-catenin signaling in mammals, whereas aberrant Wnt pathway activation in ISCs triggers the development of human colorectal carcinoma. Herein, we have utilized the Drosophila midgut, a powerful model for ISC regulation, to elucidate the mechanisms by which Wingless (Wg)/Wnt(More)