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[Shape change in human megakaryoblastic leukemia cells, MEG-01]
S Goto1, M Kobayashi, H Hidaka
1First Department of Internal Medicine, Nagoya University School of Medicine.
Abstract:
We investigated the intracellular processes of the shape change in the human megakaryoblastic leukemia cell, MEG-01, by platelet agonists. Thrombin induced the formation of many pseudopods. This shape change was also induced by TPA and A23187, but not by ADP, collagen, or epinephrine. Electron microscopy and FITC-labeled phalloidin staining revealed thick submembranous microfilament bundles in the pseudopods of the shape-changed cells induced by thrombin. Shape change was inhibited by cytochalasin B. Protein kinase C (RKC) inhibitor, H-7, markedly inhibited thrombin-induced shape change, while the myosin light chain kinase (MLCK) inhibitor, ML-9 did not. These results suggest that thrombin-induced reorganization of microfilaments and shape change of MEG-01 cells are mediated by PKC but not by MLCK.
Insights
Thrombin triggers shape changes in MEG-01 cells by reorganizing microfilaments via Protein Kinase C (PKC), not Myosin Light Chain Kinase (MLCK). This reveals key intracellular signaling pathways in cell morphology.
Area of Science:
- Cell Biology
- Hematology
- Biochemistry
Context:
- Human megakaryoblastic leukemia cell line (MEG-01) is a model for megakaryocyte studies.
- Platelet agonists play crucial roles in cellular processes, including shape change.
- Understanding intracellular signaling is vital for cell function research.
Purpose:
- To investigate the intracellular mechanisms underlying agonist-induced shape change in MEG-01 cells.
- To identify the specific signaling pathways involved in thrombin-induced cell morphology.
- To differentiate the roles of Protein Kinase C (PKC) and Myosin Light Chain Kinase (MLCK) in this process.
Summary:
- Thrombin, TPA, and A23187 induced significant shape changes in MEG-01 cells, characterized by pseudopod formation.
- Electron microscopy and phalloidin staining revealed microfilament bundle reorganization in thrombin-treated cells.
- Inhibition studies indicated that thrombin-induced shape change is mediated by PKC, as evidenced by H-7 inhibition, and not by MLCK, as ML-9 had no significant effect.
Impact:
- This study elucidates the signaling cascade involving PKC in thrombin-mediated microfilament reorganization and cell shape change.
- Findings contribute to understanding platelet agonist signaling and cellular responses in leukemia cell models.
- Identifies specific molecular targets for potential therapeutic interventions related to cell morphology and function.