Nuclear localization of Src-family tyrosine kinases is required for growth factor-induced euchromatinization.
Src-family kinases (SFKs), which participate in various signaling events, are found at not only the plasma membrane but also several subcellular compartments, including the nucleus. Nuclear structural changes are frequently observed during transcription, cell differentiation, senescence, tumorigenesis, and cell cycle. However, little is known about signal transduction in the alteration of chromatin texture. Here, we develop a pixel imaging method for quantitatively evaluating chromatin structural changes. Growth factor stimulation increases euchromatic hypocondensation and concomitant heterochromatic hypercondensation in G(1) phase, and the levels reach a plateau by 30 min, sustain for at least 5 h and return to the basal levels after 24 h. Serum-activated SFKs in the nucleus were more frequently detected in the euchromatin areas than the heterochromatin areas. Nuclear expression of kinase-active SFKs, but not unrelated Syk kinase, drastically increases both euchromatinization and heterochromatinization in a manner dependent on the levels of nuclear tyrosine phosphorylation. However, growth factor stimulation does not induce chromatin structural changes in SYF cells lacking SFKs, and reintroduction of one SFK member into SYF cells can, albeit insufficiently, induce chromatin structural changes. These results suggest that nuclear tyrosine phosphorylation by SFKs plays an important role in chromatin structural changes upon growth factor stimulation.
Takahashi
Akinori
A
Department of Molecular Cell Biology, Graduate School of Pharmaceutical Sciences, Chiba University, Chuo-ku, Chiba 260-8675, Japan.
Obata
Yuuki
Y
Fukumoto
Yasunori
Y
Nakayama
Yuji
Y
Kasahara
Kousuke
K
Kuga
Takahisa
T
Higashiyama
Yukihiro
Y
Saito
Takashi
T
Yokoyama
Kazunari K
KK
Yamaguchi
Naoto
N
D000730:Androstadienes / Q000378:metabolism; D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D019556:COS Cells; D002453:Cell Cycle / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism / Q000648:ultrastructure; D002522:Chlorocebus aethiops; D022041:Euchromatin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D008856:Microscopy, Fluorescence / Q000379:methods*; D009690:Nucleic Acid Conformation; D047428:Protein Kinase Inhibitors / Q000378:metabolism; D054648:Protein Phosphatase 2 / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D014638:Vanadates / Q000378:metabolism; D000077191:Wortmannin; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism*
D000730:Androstadienes; D000911:Antibodies, Monoclonal; D022041:Euchromatin; D006657:Histones; D036341:Intercellular Signaling Peptides and Proteins; D047428:Protein Kinase Inhibitors; D014638:Vanadates; D019061:src-Family Kinases; D054648:Protein Phosphatase 2; D000077191:Wortmannin