title: Nuclear compartmentalization of FAK and FRNK in cardiac myocytes.
abstract: Focal adhesion kinase (FAK) and FAK-related non-kinase (FRNK) accumulate in the nucleus of cardiac myocytes during hypertensive hypertrophy. Nuclear FAK and FRNK are phosphorylated on different serines and form distinct bright spots. The subnuclear distribution of serine-phosphorylated FAK and FRNK was examined in this study by double labeling with fibrillarin, a component of nucleoli, and Sam68, a constituent of Sam68 nuclear bodies. We also investigated the role of protein kinase C (PKC)-mediated phosphorylation of FAK and FRNK on nuclear translocation. PKC activation by 12-O-tetradecanoylphorbol 13-acetate treatment increased serine phosphorylation of FAK and FRNK. Specifically, FAK was phosphorylated on serine 722 but not serine 910. On the other hand, FRNK was phosphorylated on serine 217, the equivalent site of FAK serine 910, but not serine 30, the homologous site of FAK serine 722. Serine-phosphorylated FAK and FRNK redistributed into the nucleus and formed distinct patterns. FAK with phosphorylation on serine 722 colocalized with Sam68 but not fibrillarin. On the contrary, FRNK phosphorylated on 217 coexisted with fibrillarin but not Sam68. Immunoprecipitation also confirmed that FAK associated with Sam68 and FRNK interacted with fibrillarin, respectively. These results suggest that FAK and FRNK target different nuclear subdomains by their association with distinct nuclear proteins.
authors.affiliation: Cardiovascular Research Institute-South Dakota Health Research Foundation, 1100 East 21st Street, Sioux Falls, SD 57105, USA.
authors.forename: Xian Ping
authors.initials: XP
authors.lastname: Yi
authors.forename: Jibin
authors.initials: J
authors.lastname: Zhou
authors.forename: Lu
authors.initials: L
authors.lastname: Huber
authors.forename: Jiaxiang
authors.initials: J
authors.lastname: Qu
authors.forename: Xuejun
authors.initials: X
authors.lastname: Wang
authors.forename: A Martin
authors.initials: AM
authors.lastname: Gerdes
authors.forename: Faqian
authors.initials: F
authors.lastname: Li
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism*; D002469:Cell Separation; D002868:Chromosomal Proteins, Non-Histone / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism*; D006333:Heart Failure / Q000201:enzymology / Q000235:genetics; D047468:Immunoprecipitation; D018613:Microscopy, Confocal; D032383:Myocytes, Cardiac / Q000201:enzymology*; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012694:Serine / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D010750:Phosphoproteins; D016601:RNA-Binding Proteins; C047458:fibrillarin; D012694:Serine; C113183:FAK-related nonkinase; D011505:Protein-Tyrosine Kinases; D051416:Focal Adhesion Protein-Tyrosine Kinases; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate