Gwang-Min Choi

Components of microbial cell walls are potent activators of innate immune responses in animals. For example, the mammalian TLR4 signaling pathway is activated by bacterial lipopolysaccharide and is required for resistance to infection by Gram-negative bacteria. Other components of microbial surfaces, such as peptidoglycan, are also potent activators of innate immune responses, but less is known about how those components activate host defense. Here we show that a peptidoglycan recognition protei

Drosophila peptidoglycan recognition protein LC (PGRP-LC), a transmembrane protein required for the response to bacterial infection, acts at the top of a cytoplasmic signaling cascade that requires the death-domain protein Imd and an IkappaB kinase to activate Relish, an NF-kappaB family member. It is not clear how binding of peptidoglycan to the extracellular domain of PGRP-LC activates intracellular signaling because its cytoplasmic domain has no homology to characterized proteins. Here, we de

Classical cadherin-mediated interactions between axons and dendrites are critical to target selection and synapse assembly. However, the molecular mechanisms by which these interactions are controlled are incompletely understood. In the Drosophila visual system, N-cadherin is required in both photoreceptor (R cell) axons and their targets to mediate stabilizing interactions required for R cell target selection. Here we identify the scaffolding protein Liprin-alpha as a critical component in this

The mechanism underlying immune system recognition of different types of pathogens has been extensively studied over the past few decades; however, the mechanism by which healthy self-tissue evades an attack by its own immune system is less well-understood. Here, we established an autoimmune model of melanotic mass formation in Drosophila by genetically disrupting the basement membrane. We found that the basement membrane endows otherwise susceptible target tissues with self-tolerance that preve

We have screened the third chromosome of Drosophila melanogaster for mutations that prevent the normal immune response. We identified mutant lines on the basis of their failure to induce transcription of an antibacterial peptide gene in response to infection or their failure to form melanized clots at the site of wounding. These mutations define 14 genes [immune response deficient (ird) genes] that have distinct roles in the immune response. We have identified the molecular basis of several ird

ABSTRACT Cell–cell fusion is widely observed during development and disease, and imposes a dramatic change on participating cells. Cell fusion should be tightly controlled, but the underlying mechanism is poorly understood. Here, we found that the JAK/STAT pathway suppressed cell fusion during wound healing in the Drosophila larval epidermis, restricting cell fusion to the vicinity of the wound. In the absence of JAK/STAT signaling, a large syncytium containing a 3-fold higher number of nuclei t

Rho-family small GTPases regulate epithelial cell sheet migration by organizing actin and myosin during wound healing. Here, we report that Pak3, but not Pak1, is a downstream target protein for Rac1 in wound closure of the Drosophila larval epidermis. Pak3-deficient larvae failed to close a wound hole and this defect was not rescued by Pak1 expression, indicating differential functions of the two proteins. Pak3 localized to the wound margin, which selectively required Rac1. Pak3-deficient larva