The phosphoinositol 3,4-bisphosphate-binding protein TAPP1 interacts with syntrophins and regulates actin cytoskeletal organization.
Syntrophins are scaffold proteins of the dystrophin glycoprotein complex (DGC), which target ion channels, receptors, and signaling proteins to specialized subcellular domains. A yeast two-hybrid screen of a human brain cDNA library with the PSD-95, Discs-large, ZO-1 (PDZ) domain of gamma1-syntrophin yielded overlapping clones encoding the C terminus of TAPP1, a pleckstrin homology (PH) domain-containing adapter protein that interacts specifically with phosphatidylinositol 3,4-bisphosphate (PI(3,4)P(2)). In biochemical assays, the C terminus of TAPP1 bound specifically to the PDZ domains of gamma1-, alpha1-, and beta2-syntrophin and was required for syntrophin binding and for the correct subcellular localization of TAPP1. TAPP1 is recruited to the plasma membrane of cells stimulated with platelet-derived growth factor (PDGF), a motogen that produces PI(3,4)P(2). Cell migration in response to PDGF stimulation is characterized by a rapid reorganization of the actin cytoskeleton, which gives rise to plasma membrane specializations including peripheral and dorsal circular ruffles. Both TAPP1 and syntrophins were localized to PDGF-induced circular membrane ruffles in NIH-3T3 cells. Ectopic expression of TAPP1 potently blocked PDGF-induced formation of dorsal circular ruffles, but did not affect peripheral ruffling. Interestingly, coexpression of alpha1- or gamma1-syntrophin with TAPP1 prevented the blockade of circular ruffling. In addition to syntrophins, several other proteins of the DGC were enriched in circular ruffles. Collectively, our results suggest syntrophins regulate the localization of TAPP1, which may be important for remodeling the actin cytoskeleton in response to growth factor stimulation.
Department of Cellular and Molecular Medicine, Centre for Neuromuscular Disease, University of Ottawa, 451 Smyth Rd., Ottawa, ON K1H 8M5, Canada.
Angela
A
Hogan
Yury
Y
Yakubchyk
Josée
J
Chabot
Christopher
C
Obagi
Elias
E
Daher
Kazuhiko
K
Maekawa
Stephen H
SH
Gee
D000199:Actins / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001921:Brain / Q000196:embryology / Q000378:metabolism; D019556:COS Cells; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement; D003001:Cloning, Molecular; D003599:Cytoskeleton / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D000074288:Discs Large Homolog 1 Protein; D000076122:Disks Large Homolog 4 Protein; D016189:Dystrophin / Q000378:metabolism; D049029:Dystrophin-Associated Proteins / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes / Q000737:chemistry; D006133:Growth Substances / Q000378:metabolism; D051528:Guanylate Kinases; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry / Q000502:physiology*; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008856:Microscopy, Fluorescence; D041681:NIH 3T3 Cells; D009419:Nerve Tissue Proteins / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates / Q000737:chemistry; D010750:Phosphoproteins / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D013997:Time Factors; D014162:Transfection; D020798:Two-Hybrid System Techniques; D062826:Zonula Occludens-1 Protein
D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; C513314:DLG1 protein, human; D018076:DNA, Complementary; D000074288:Discs Large Homolog 1 Protein; D000076122:Disks Large Homolog 4 Protein; C000614189:Dlg1 protein, mouse; C501447:Dlg4 protein, mouse; D016189:Dystrophin; D049029:Dystrophin-Associated Proteins; D000939:Epitopes; D006133:Growth Substances; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D018129:Phosphatidylinositol Phosphates; D010750:Phosphoproteins; C461495:Plekha1 protein, mouse; D011506:Proteins; D011993:Recombinant Fusion Proteins; C569042:TJP1 protein, human; C569043:Tjp1 protein, mouse; D062826:Zonula Occludens-1 Protein; C060980:phosphatidylinositol 3,4-diphosphate; C033652:postsynaptic density proteins; C091824:syntrophin; D004247:DNA; D051528:Guanylate Kinases