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A role of GAGs in ECM on morphogenesis of megakaryocytes
1Department of Haematology/Oncology, University of Tokyo, Japan.
Abstract:
The morphogenesis of megakaryocytes that results in the formation of cytoplasmic processes is thought to be the final maturation step before liberation of platelets. We studied the in vitro effects of glycosaminoglycans (GAGs) which are abundant in the bone marrow extracellular matrices, on the morphogenesis of murine megakaryocytes and compared them with those of thrombopoietic cytokines. Heparin, heparan sulfate, chondroitin-6 sulfate, and dermatan sulfate promoted the formation of megakaryocytic processes. Hyaluronic acid failed to support this phenomenon, suggesting that sulfated GAGs in extracellular matrices are involved in the morphogenesis of megakaryocytes. Sulfated GAGs began to act on megakaryocytes with a higher ploidy (16N-32N) from 6 to 24h after incubation, whereas neither rhIL-6 nor rhIL-11 affected this early phase. Our findings indicate that sulfated GAGs promote the morphogenesis of murine megakaryocytes and participate in thrombopoiesis in a different manner from that of cytokines such as rhIL-6 and rhIL-11.
Insights
Sulfated glycosaminoglycans (GAGs) promote megakaryocyte maturation and platelet formation. These molecules influence megakaryocyte cytoplasmic process development, distinct from cytokine actions.
Area of Science:
- Hematology
- Cell Biology
- Biochemistry
Background:
- Megakaryocyte (MK) morphogenesis, involving cytoplasmic process formation, is crucial for platelet production.
- Bone marrow extracellular matrix (ECM) contains abundant glycosaminoglycans (GAGs).
Purpose of the Study:
- To investigate the in vitro effects of various GAGs on murine megakaryocyte morphogenesis.
- To compare GAG effects with those of thrombopoietic cytokines like rhIL-6 and rhIL-11.
Main Methods:
- In vitro incubation of murine megakaryocytes with different GAGs (heparin, heparan sulfate, chondroitin-6 sulfate, dermatan sulfate, hyaluronic acid).
- Assessment of megakaryocyte cytoplasmic process formation.
- Comparison with the effects of recombinant human interleukin-6 (rhIL-6) and rhIL-11.
Main Results:
- Sulfated GAGs (heparin, heparan sulfate, chondroitin-6 sulfate, dermatan sulfate) significantly promoted megakaryocyte process formation.
- Hyaluronic acid did not support megakaryocyte morphogenesis.
- Sulfated GAGs acted on higher ploidy megakaryocytes (16N-32N) within 6-24 hours, preceding cytokine effects.
Conclusions:
- Sulfated GAGs are key regulators of megakaryocyte morphogenesis and platelet formation.
- GAGs influence megakaryocyte maturation through mechanisms distinct from those of thrombopoietic cytokines.