Small Rab GTPase Rab7b promotes megakaryocytic differentiation by enhancing IL-6 production and STAT3-GATA-1 association.
Induction of the differentiation of human leukemia cells is a useful strategy in treatment of human leukemia. However, the molecular mechanisms involved in leukemia cell differentiation have not been fully elucidated. Interleukin 6 (IL-6) is a pleiotropic cytokine acting on a variety of cell types, and plays important roles in hematopoiesis. GATA binding protein 1 (GATA-1) is an important transcription factor involved in either megakaryocytic or erythrocytic differentiation. Herein we report that Rab7b, a late endosome/lysosome-localized myeloid small GTPase, promotes phorbol-12-myristate-13-acetate (PMA)-induced megakaryocytic differentiation by increasing nuclear factor κB (NF-κB)-dependent IL-6 production and subsequently enhancing the association of activated signal transducer and activator of transcription 3 (STAT3) with GATA-1. By using PMA-induced megakaryocytic differentiation of leukemia cells as a model, we investigated the roles of Rab7b in megakaryocytic differentiation. We find that Rab7b can potentiate PMA-induced upregulation of megakaryocytic markers, production of IL-6, and activation of NF-κB. Inhibitor of NF-κB and neutralizing antibodies for IL-6 or the IL-6 signaling receptor gp130 can block the effects of Rab7b in megakaryocytic differentiation. In Rab7b-silenced cells, PMA-induced activation of NF-κB, IL-6 production, and megakaryocytic differentiation are impaired. Furthermore, we demonstrate that IL-6-induced activation of STAT3 and the subsequent association of STAT3 with GATA-1 may contribute to PMA-induced and Rab7b-mediated transcriptional upregulation of megakaryocytic differentiation markers. Therefore, our data suggest that Rab7b may play important roles in megakaryopoiesis by activating NF-κB and promoting IL-6 production. Our study also indicates that the IL-6-induced association of STAT3 with GATA-1 may regulate megakaryocytic differentiation.
Department of Hematology, First Affiliated Hospital, Zhejiang University School of Medicine, 38 Zheda Road, Hangzhou, 310027, China.
Donghua
D
He
Taoyong
T
Chen
Mingjin
M
Yang
Xuhui
X
Zhu
Chen
C
Wang
Xuetao
X
Cao
Zhen
Z
Cai
D002454:Cell Differentiation; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D050982:GATA1 Transcription Factor / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D020014:K562 Cells; D008533:Megakaryocytes / Q000166:cytology* / Q000201:enzymology; D016328:NF-kappa B / Q000378:metabolism; D034622:RNA Interference; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
D004268:DNA-Binding Proteins; D050982:GATA1 Transcription Factor; C494688:GATA1 protein, human; D015850:Interleukin-6; D016328:NF-kappa B; D050796:STAT3 Transcription Factor; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020691:rab GTP-Binding Proteins