Kirito Keita, Osawa Masatake, Morita Haruhiko, Shimizu Ritsuko, Yamamoto Masayuki, Oda Atsushi, Fujita Hiroyoshi, Tanaka Masaru, Nakajima Koichi, Miura Yasusada, Ozawa Keiya, Komatsu Norio
Division of Hematology, Department of Medicine, Jichi Medical School, Tochigi, Japan.
Blood. 2002 May 1;99(9):3220-7. doi: 10.1182/blood.v99.9.3220.
The signal transducer and activator of transcription 3 (Stat3), a member of the Stat family of proteins, is commonly activated by thrombopoietic cytokines including thrombopoietin (TPO), interleukin (IL)-6, and interleukin-11. This finding strongly suggested that Stat3 has an important role in megakaryopoiesis and thrombopoiesis. To clarify the functional role of Stat3 in in vivo megakaryopoiesis and thrombopoiesis, we generated transgenic mice overexpressing a dominant-negative Stat3, Stat3F, to suppress the function of endogenous Stat3. To accomplish the selective expression of Stat3F in megakaryocytic lineage cells, we used the regulatory gene region of GATA-1 transcription factor selectively expressed in megakaryocytic and erythroid lineage cells. Two independent transgenic (Tg) mice lines were established. It was confirmed by Western blotting analysis that Stat3F proteins were highly expressed in the platelets from the Tg mice. In addition, it was found that Stat3 activation induced by TPO stimulation was drastically suppressed in these Tg mice compared with littermates. These findings indicate that Stat3F works well in the Tg mice. Platelet counts were within the normal range in steady-state conditions and were recovered normally from transient thrombocytopenia induced by antiplatelet serum injection. Interestingly, the platelet recovery from myelosuppression after 5-fluorouracil treatment was significantly delayed in the Tg mice. Collectively, our results strongly suggest that Stat3 plays an important role in the early stage of megakaryopoiesis, presumably through the expansion of megakaryocytic progenitor cells.
信号转导与转录激活因子3（Stat3）是Stat蛋白家族的成员之一，通常被包括血小板生成素（TPO）、白细胞介素（IL）-6和白细胞介素-11在内的血小板生成细胞因子激活。这一发现强烈表明Stat3在巨核细胞生成和血小板生成中具有重要作用。为了阐明Stat3在体内巨核细胞生成和血小板生成中的功能作用，我们构建了过表达显性负性Stat3（Stat3F）的转基因小鼠，以抑制内源性Stat3的功能。为了在巨核细胞系细胞中实现Stat3F的选择性表达，我们使用了在巨核细胞和红细胞系细胞中选择性表达的GATA-1转录因子的调控基因区域。建立了两个独立的转基因（Tg）小鼠品系。通过蛋白质免疫印迹分析证实，Stat3F蛋白在Tg小鼠的血小板中高表达。此外，发现与同窝小鼠相比，这些Tg小鼠中TPO刺激诱导的Stat3激活被显著抑制。这些发现表明Stat3F在Tg小鼠中发挥了良好的作用。在稳态条件下血小板计数在正常范围内，并且在注射抗血小板血清诱导的短暂血小板减少后能够正常恢复。有趣的是，在5-氟尿嘧啶治疗后骨髓抑制后的血小板恢复在Tg小鼠中显著延迟。总的来说，我们的结果强烈表明Stat3在巨核细胞生成的早期阶段发挥重要作用，可能是通过巨核细胞祖细胞的扩增来实现的。
