Drosophila integrin-linked kinase is required at sites of integrin adhesion to link the cytoskeleton to the plasma membrane.
Integrin-linked kinase (ILK) was identified by its interaction with the cytoplasmic tail of human beta1 integrin and previous data suggest that ILK is a component of diverse signaling pathways, including integrin, Wnt, and protein kinase B. Here we show that the absence of ILK function in Drosophila causes defects similar to loss of integrin adhesion, but not similar to loss of these signaling pathways. ILK mutations cause embryonic lethality and defects in muscle attachment, and clones of cells lacking ILK in the adult wing fail to adhere, forming wing blisters. Consistent with this, an ILK-green fluorescent protein fusion protein colocalizes with the position-specific integrins at sites of integrin function: muscle attachment sites and the basal junctions of the wing epithelium. Surprisingly, mutations in the kinase domain shown to inactivate the kinase activity of human ILK do not show any phenotype in Drosophila, suggesting a kinase-independent function for ILK. The muscle detachment in ILK mutants is associated with detachment of the actin filaments from the muscle ends, unlike integrin mutants, in which the primary defect is detachment of the plasma membrane from the extracellular matrix. Our data suggest that ILK is a component of the structure linking the cytoskeleton and the plasma membrane at sites of integrin-mediated adhesion.
Wellcome/CRC Institute and Department of Anatomy, University of Cambridge, Cambridge CB2 1QR, United Kingdom.
C G
CG
Zervas
S L
SL
Gregory
N H
NH
Brown
D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D020134:Catalytic Domain; D002448:Cell Adhesion; D002462:Cell Membrane / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology* / Q000196:embryology / Q000201:enzymology / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D017403:In Situ Hybridization; D016023:Integrins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009132:Muscles / Q000002:abnormalities / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction; D015534:Trans-Activators; D014921:Wings, Animal / Q000002:abnormalities / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D051176:beta Catenin; D000099200:Scaffold Protein ILK
D000199:Actins; D003598:Cytoskeletal Proteins; D016023:Integrins; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger; D015534:Trans-Activators; D051176:beta Catenin; D000099200:Scaffold Protein ILK; C495270:CTNNB1 protein, human