title: Integrins on eggs: focal adhesion kinase is activated at fertilization, forms a complex with integrins, and is necessary for cortex formation and cell cycle initiation.
abstract: We investigate the proposal that integrins and focal adhesion kinase (FAK) form a complex that has structural and signaling functions in eggs. FAK protein is present in eggs and is phosphorylated at fertilization. pY(397)FAK localizes to the membrane 30 min after fertilization, which correlates with the expression of βC integrins and egg cortex development. The βC integrin and pY(397)FAK coimmunoprecipitate from egg cortex lysates. PF573 228 and Y11, inhibitors of FAK, interfere with pronuclear fusion and reduce the abundance of pY(397)FAK and cortical actin without affecting microvillar actin. Cyclin E normally accumulates in the nucleus 15 min after fertilization, then returns to background levels. PF573 228- or Y11-treated eggs accumulate cyclin E in the nucleus; however, levels remain high. In addition, PF573 228 interferes with the accumulation of pERK1/2 in the nucleus and in eggs initiating mitosis. Injection of eggs with a fusion protein consisting of the focal adhesion-targeting domain of FAK fused to green fluorescent protein interferes with cortex formation and produces abnormal nuclei. These data indicate that an integrin-FAK adhesion complex forms at the egg surface that functions in formation of actin arrays in the egg cortex and provides signaling inputs for cell cycle initiation.
authors.affiliation: Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8P 5C2, Canada.
authors.forename: D
authors.initials: D
authors.lastname: Chan
authors.forename: C J
authors.initials: CJ
authors.lastname: Thomas
authors.forename: V J
authors.initials: VJ
authors.lastname: Taylor
authors.forename: R D
authors.initials: RD
authors.lastname: Burke
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D019927:Cyclin E / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D005306:Fertilization / Q000502:physiology*; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006572:Heterocyclic Compounds, Bridged-Ring / Q000494:pharmacology; D015151:Immunoblotting; D039641:Integrin beta Chains / Q000378:metabolism*; D008297:Male; D018613:Microscopy, Confocal; D010063:Ovum / Q000166:cytology / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D015363:Quinolones / Q000494:pharmacology; D047270:Strongylocentrotus purpuratus / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D013450:Sulfones / Q000494:pharmacology; D013997:Time Factors; D015053:Zygote / Q000166:cytology / Q000378:metabolism
chemical_list: C574188:1-(2-hydroxyethyl)-3,5,7-triaza-1-azoniatricyclo(3.3.1.1(3,7))decane bromide; C521108:6-(4-(3-(methylsulfonyl)benzylamino)-5-(trifluoromethyl)pyrimidin-2-ylamino)-3,4-dihydroquinolin-2(1H)-one; D019927:Cyclin E; D006572:Heterocyclic Compounds, Bridged-Ring; D039641:Integrin beta Chains; D015363:Quinolones; D013450:Sulfones; D049452:Green Fluorescent Proteins; D051416:Focal Adhesion Protein-Tyrosine Kinases; D048049:Extracellular Signal-Regulated MAP Kinases