Role of integrin-linked kinase in nerve growth factor-stimulated neurite outgrowth.
The role of integrin-linked kinase (ILK), a kinase that is involved in various cellular processes, including adhesion and migration, has not been studied in primary neurons. Using mRNA dot blot and Western blot analysis of ILK in rat and human brain tissue, we found that ILK is expressed in various regions of the CNS. Immunohistochemical and immunocytochemical techniques revealed granular ILK staining that is enriched in neurons and colocalizes with the beta1 integrin subunit. The role of ILK in neurite growth promotion by NGF was studied in rat pheochromocytoma cells and dorsal root ganglion neurons using a pharmacological inhibitor of ILK (KP-392) or after overexpression of dominant-negative ILK (ILK-DN). Both molecular and pharmacological inhibition of ILK activity significantly reduced NGF-induced neurite outgrowth. Survival assays indicate that KP-392-induced suppression of neurite outgrowth occurred in the absence of cell death. ILK kinase activity was stimulated by NGF. NGF-mediated stimulation of phosphorylation of both AKT and the Tau kinase glycogen synthase kinase-3 (GSK-3) was inhibited in the presence of KP-392 and after overexpression of ILK-DN. Consequently, ILK inhibition resulted in an increase in the hyperphosphorylation of Tau, a substrate of GSK-3. Together these findings indicate that ILK is an important effector in NGF-mediated neurite outgrowth.
Mills
Julia
J
Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada V6T 123.
Digicaylioglu
Murat
M
Legg
Arthur T
AT
Young
Clint E
CE
Young
Sean S
SS
Barr
Alasdair M
AM
Fletcher
Lauren
L
O'Connor
Timothy P
TP
Dedhar
Shoukat
S
D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000201:enzymology; D002642:Chick Embryo; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005109:Extracellular Matrix / Q000378:metabolism; D005727:Ganglia, Spinal / Q000166:cytology / Q000201:enzymology; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology / Q000201:enzymology; D006801:Humans; D007150:Immunohistochemistry; D019012:Integrin beta1 / Q000096:biosynthesis; D020932:Nerve Growth Factor / Q000494:pharmacology*; D016501:Neurites / Q000187:drug effects* / Q000648:ultrastructure; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D009928:Organ Specificity; D016716:PC12 Cells; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000187:drug effects / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D016875:tau Proteins / Q000378:metabolism; D000099200:Scaffold Protein ILK
D004791:Enzyme Inhibitors; D038362:Glycogen Synthase Kinase 3; D019012:Integrin beta1; D020932:Nerve Growth Factor; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger; D016875:tau Proteins; D000099200:Scaffold Protein ILK; C494918:AKT1 protein, human; C494920:Akt1 protein, rat