title: ILK mediates actin filament rearrangements and cell migration and invasion through PI3K/Akt/Rac1 signaling.
abstract: One of the hallmarks of integrin signaling is an increase in cell migration and invasion, both of which are associated with actin filament rearrangements. Integrin-linked kinase (ILK) is a cytoplasmic effector of integrin receptors. ILK is known to be involved in multiple cellular functions. However, the signaling pathways involved in ILK-mediated cellular structure and motility remain to be elucidated. Here, we have demonstrated that overexpression of ILK was sufficient to induce actin filament rearrangements, to form cell motility structures, and to increase cell migration and invasion in a phosphatidylinositol 3-kinase (PI3K)-dependent manner. This corresponds with the activation of both Akt and p70 ribosomal protein S6 kinase (p70S6K1). Overexpression of dominant-negative mutants of Akt inhibited ILK-dependent activation of p70S6K1, indicating that Akt is upstream of p70S6K1 in response to ILK signaling. Overexpression of ILK was sufficient to induce Rac1 activation, which was abolish by a PI3K inhibitor, indicating that Rac1 activity is involved in ILK signaling in a PI3K dependent manner. Inhibition of Akt, Rac1, or p70S6K1 inhibited the effects of ILK on actin filaments and cell migration, suggesting a regulatory role of the PI3K/Akt/p70S6K1/Rac1 signaling pathway in response to ILK signaling. We have shown that overexpression of a dominant-negative ILK was sufficient to abolish fibronectin peptide (PHSRN)-induced rearrangements of actin filaments and cell migration and invasion. Taken together, our results identify a mechanism through which ILK can regulate both integrin-associated rearrangements of actin filaments and cell migration and invasion at the integrin receptor-proximal region.
authors.affiliation: Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26506, USA. yaq2@cdc.gov
authors.forename: Yong
authors.initials: Y
authors.lastname: Qian
authors.forename: Xiaosong
authors.initials: X
authors.lastname: Zhong
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Flynn
authors.forename: Jenny Z
authors.initials: JZ
authors.lastname: Zheng
authors.forename: Meng
authors.initials: M
authors.lastname: Qiao
authors.forename: Chuanyue
authors.initials: C
authors.lastname: Wu
authors.forename: Shoukat
authors.initials: S
authors.lastname: Dedhar
authors.forename: Xianglin
authors.initials: X
authors.lastname: Shi
authors.forename: Bing-Hua
authors.initials: BH
authors.lastname: Jiang
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002465:Cell Movement; D002645:Chickens; D003593:Cytoplasm / Q000378:metabolism; D004789:Enzyme Activation; D005347:Fibroblasts / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism; D005799:Genes, Dominant; D006801:Humans; D016023:Integrins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism* / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D015398:Signal Transduction; D014945:Wound Healing; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*; D000099200:Scaffold Protein ILK
chemical_list: D005353:Fibronectins; D016023:Integrins; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein; D000099200:Scaffold Protein ILK; C494918:AKT1 protein, human