| First Author | Takizawa H | Year | 2008 |
| Journal | Exp Hematol | Volume | 36 |
| Issue | 7 | Pages | 897-906 |
| PubMed ID | 18456388 | Mgi Jnum | J:136990 |
| Mgi Id | MGI:3797465 | Doi | 10.1016/j.exphem.2008.02.004 |
| Citation | Takizawa H, et al. (2008) Growth and maturation of megakaryocytes is regulated by Lnk/Sh2b3 adaptor protein through crosstalk between cytokine- and integrin-mediated signals. Exp Hematol 36(7):897-906 |
| abstractText | OBJECTIVE: Various cytokines and growth factors control the differentiation and maturation of megakaryocytes (MKs). However, the mechanism regulating platelet release from MKs is not well understood. Here, we investigated a role of Lnk/Sh2b3, an intracellular adaptor protein, in megakaryopoiesis. MATERIALS AND METHODS: Number of MK progenitor in bone marrow (BM) of wild-type or Lnk(-/-) mice and their sensitivity to thrombopoietin (TPO) were determined in colony-forming unit assay. Using BM-derived wild-type or Lnk(-/-) MKs stimulated with TPO, activation of the signaling molecules was biochemically analyzed and effect of integrin stimulation on TPO signals was studied by addition of vascular cell adhesion molecule (VCAM-1). Platelet production from MKs in the presence of VCAM-1 was counted by flow cytometry and their morphological change was observed by time-lapse microscopy. RESULTS: Lnk(-/-) mice showed elevated platelets and mature MKs due to enhanced sensitivity of progenitors to TPO. Erk1/2 phosphorylation induced by TPO was augmented and prolonged in Lnk(-/-) MKs while activation of signal transducers and activators of transcription (Stat)3, Stat5, and Akt was normal. Wild-type MKs, but not in Lnk(-/-) MKs on VCAM-1 showed reduced Stat5 phosphorylation and mitogen-activated protein kinases activation upon stimulation with TPO. Additionally, the presence of VCAM in culture accelerated spontaneous platelet release from mature wild-type MKs, but not from Lnk(-/-) MKs. CONCLUSIONS: Results suggest that contact of MKs with adhesion molecules via integrins might contribute to platelet release, which is under Lnk-mediated regulation of Stat-5 activation and show that Lnk functions in responses controlled by cell adhesion and in crosstalk between integrin- and cytokine-mediated signaling. |
