Potentiated activation of VLA-4 and VLA-5 accelerates proplatelet-like formation.
Fibronectin (FN) plays important roles in the proliferation, differentiation, and maintenance of megakaryocytic-lineage cells through FN receptors. However, substantial role of FN receptors and their functional assignment in proplatelet-like formation (PPF) of megakaryocytes are not yet fully understood. Herein, we investigated the effects of FN receptors on PPF using the CHRF-288 human megakaryoblastic cell line, which expresses VLA-4 and VLA-5 as FN receptors. FN and phorbol 12-myristate 13-acetate (PMA) were essential for inducing PPF in CHRF-288 cells. Blocking experiments using anti-β1-integrin monoclonal antibodies indicated that the adhesive interaction with FN via VLA-4 and VLA-5 were required for PPF. PPF induced by FN plus PMA was accelerated when CHRF-288 cells were enforced adhering to FN by TNIIIA2, a peptide derived from tenascin-C, which we recently found to induce β1-integrin activation. Adhesion to FN enhanced PMA-stimulated activation of extracellular signal-regulated protein kinase 1 (ERK1)/2 and enforced adhesion to FN via VLA-4 and VLA-5 by TNIIIA2-accelerated activation of ERK1/2 with FN plus PMA. However, c-Jun amino-terminal kinase 1 (JNK1), p38, and phosphoinositide-3 kinase (PI3K)/Akt were not stimulated by FN plus PMA, even with TNIIIA2. Thus, the enhanced activation of ERK1/2 by FN, PMA plus TNIIIA2 was responsible for acceleration of PPF with FN plus PMA.
Department of Gastroenterology and Hematology, Miyazaki University, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan. m-takuya@med.kagawa-u.ac.jp
Takuya
T
Matsunaga
Fumio
F
Fukai
Takuro
T
Kameda
Kotaro
K
Shide
Haruko
H
Shimoda
Eri
E
Torii
Ayako
A
Kamiunten
Masaaki
M
Sekine
Shojirou
S
Yamamoto
Tomonori
T
Hidaka
Yoko
Y
Kubuki
Shigeyuki
S
Yokokura
Makiko
M
Uemura
Akihito
A
Matsuoka
Fusako
F
Waki
Kensuke
K
Matsumoto
Nobuhiro
N
Kanaji
Tomoya
T
Ishii
Osamu
O
Imataki
Hiroaki
H
Dobashi
Shuji
S
Bandoh
Kazuya
K
Shimoda
D001792:Blood Platelets / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D004357:Drug Synergism; D006801:Humans; D039041:Integrin alpha4beta1 / Q000378:metabolism*; D039482:Integrin alpha5 / Q000378:metabolism*; D039081:Integrin alpha5beta1 / Q000378:metabolism*; D055016:Megakaryocyte Progenitor Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008533:Megakaryocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015539:Platelet Activation / Q000187:drug effects / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000031:analogs & derivatives / Q000494:pharmacology
D039041:Integrin alpha4beta1; D039482:Integrin alpha5; D039081:Integrin alpha5beta1; C016658:phorbolol myristate acetate; D013755:Tetradecanoylphorbol Acetate