JAM3 maintains leukemia-initiating cell self-renewal through LRP5/AKT/β-catenin/CCND1 signaling
Yaping Zhang, … , Guo-Qiang Chen, Junke Zheng
Yaping Zhang, … , Guo-Qiang Chen, Junke Zheng
Published March 26, 2018
Citation Information: J Clin Invest. 2018;128(5):1737-1751. https://doi.org/10.1172/JCI93198.
View: Text | PDF
Research Article Hematology

JAM3 maintains leukemia-initiating cell self-renewal through LRP5/AKT/β-catenin/CCND1 signaling

Abstract

Leukemia-initiating cells (LICs) are responsible for the initiation, development, and relapse of leukemia. The identification of novel therapeutic LIC targets is critical to curing leukemia. In this report, we reveal that junctional adhesion molecule 3 (JAM3) is highly enriched in both mouse and human LICs. Leukemogenesis is almost completely abrogated upon Jam3 deletion during serial transplantations in an MLL-AF9–induced murine acute myeloid leukemia model. In contrast, Jam3 deletion does not affect the functions of mouse hematopoietic stem cells. Moreover, knockdown of JAM3 leads to a dramatic decrease in the proliferation of both human leukemia cell lines and primary LICs. JAM3 directly associates with LRP5 to activate the downstream PDK1/AKT pathway, followed by the downregulation of GSK3β and activation of β-catenin/CCND1 signaling, to maintain the self-renewal ability and cell cycle entry of LICs. Thus, JAM3 may serve as a functional LIC marker and play an important role in the maintenance of LIC stemness through unexpected LRP5/PDK1/AKT/GSK3β/β-catenin/CCND1 signaling pathways but not via its canonical role in cell junctions and migration. JAM3 may be an ideal therapeutic target for the eradication of LICs without influencing normal hematopoiesis.

Authors

Yaping Zhang, Fangzhen Xia, Xiaoye Liu, Zhuo Yu, Li Xie, Ligen Liu, Chiqi Chen, Haishan Jiang, Xiaoxin Hao, Xiaoxiao He, Feifei Zhang, Hao Gu, Jun Zhu, Haitao Bai, Cheng Cheng Zhang, Guo-Qiang Chen, Junke Zheng

×

Figure 4

JAM3 collaborates with LRP5 to activate β-catenin/CCND1 signaling.

Options: View larger image (or click on image) Download as PowerPoint
JAM3 collaborates with LRP5 to activate β-catenin/CCND1 signaling. (A) P...
(A) Phospho–β-catenin (S552) and total β-catenin levels were evaluated between WT and Jam3-null YFP+Mac-1+c-Kit+ LICs by immunoblotting. (B) β-Catenin levels were compared between WT and Jam3-null YFP+Mac-1+c-Kit+ LICs by immunofluorescence staining. Scale bars: 5 µm. (C) A constitutively active form of phospho–β-catenin (S37A, β-cateninCN) was subcloned in the pCDH-EF1a-T2A-mCherry vector and ectopically expressed in Jam3-null leukemia cells, which were then injected into recipient mice. Survival was compared among the mice receiving WT cells, Jam3-null cells, and β-cateninCN–overexpressing WT or Jam3-null cells (n = 5–6; *P < 0.05, **P < 0.01, log-rank test). (D) Phospho–β-catenin (S552) and total β-catenin levels were validated in leukemia cells from the rescue experiment in C. (E) The cell cycle distribution in YFP+Mac-1+c-Kit+ LICs from the rescue experiment in C was determined using Ki-67 and Hoechst 33342 staining (n = 3; ***P < 0.001, 2-way ANOVA followed by Bonferroni’s post-test). (F) StrepII-tagged JAM3 and FLAG-tagged LRP5 were overexpressed in 293T cells, and their lysates were coimmunoprecipitated by strepII beads, followed by Western blotting analysis for FLAG (LRP5). (G) A reverse coimmunoprecipitation experiment was performed after LRP5-FLAG pull-down, followed by Western blotting analysis for strepII (JAM3). The empty vector was used as the control. Experiments were conducted 3 times for validation.