Targeting mannosylation of nicastrin N-glycans attenuates γ-secretase activity and notch-dependent leukemia progression
Hua Jiang, Weixiang Bian, Yanjun Cao, Zhuo Zhang, Yijia Chen, Yue Sui, Hongqiang Qin, Xu Li
Hua Jiang, Weixiang Bian, Yanjun Cao, Zhuo Zhang, Yijia Chen, Yue Sui, Hongqiang Qin, Xu Li
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Research Article Cell biology Oncology

Targeting mannosylation of nicastrin N-glycans attenuates γ-secretase activity and notch-dependent leukemia progression

Abstract

γ-Secretase is a transmembrane protease complex that cleaves multiple type I transmembrane proteins, including amyloid precursor protein and neurogenic locus notch homolog protein (NOTCH). Although numerous γ-secretase inhibitors and modulators targeting Notch-dependent cancers have been developed in recent decades, their clinical translation has been hampered by low substrate specificity and on-target gut toxicity. Using a proteomics-based screening approach, we identified dedicator of cytokinesis protein 2 (DOCK2) as an interactor of the γ-secretase subunit nicastrin (NCSTN). We further demonstrate that DOCK2 regulates mannosylation of NCSTN N-glycans, which in turn modulates γ-secretase activity toward NOTCH receptors. Both genetic depletion of DOCK2 and pharmacological inhibition of NCSTN mannosylation with kifunensine attenuated Notch-dependent leukemia progression in vivo. Collectively, these findings uncover a regulatory mechanism underlying substrate-specific activation of γ-secretase and suggest a promising therapeutic strategy for Notch-related diseases.

Authors

Hua Jiang, Weixiang Bian, Yanjun Cao, Zhuo Zhang, Yijia Chen, Yue Sui, Hongqiang Qin, Xu Li

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Figure 7

Inhibition of N-glycosylation with kifunensine attenuates Notch-dependent leukemia in vivo.

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Inhibition of N-glycosylation with kifunensine attenuates Notch-dependen...
(A) NSG mice received tail vein injections of luciferase-expressing JURKAT cells, followed by a 3-week treatment with 10 mg/kg kifunensine or vehicle. Leukemia progression was monitored by bioluminescence imaging. (B) Representative bioluminescence image showing leukemia infiltration in vivo. n = 5. (C) Quantitative analysis of the luciferase intensity presented in B. (D and E) Tumor cell infiltration in liver and spleen tissues from each group was evaluated via H&E staining. Scale bars: 50 μm. (F) Schematic of the patient-derived xenograft model establishment and treatment workflow. Patient-derived leukemia cells were subcutaneously engrafted in NSG mice, expanded, then transplanted intravenously into secondary NSG recipients to establish a disseminated leukemia model for kifunensine efficacy testing. (G and H) Flow cytometry analysis of CD5+ leukemia cells in peripheral blood. Representative dot plots are shown. (I) H&E staining of spleen sections demonstrating extent of leukemic infiltration across treatment groups. Scale bars: 50 μm. (J) Survival curves of PDX model mice from F following kifunensine or vehicle treatment. (K) Mouse weight after kifunensine administration. (L) H&E staining of gastrointestinal tissues. Scale bars: 50 μm. (M) Plasma and brain concentration of kifunensine. Mean ± SEM; B–E, n = 5; G–I, n = 3; J, n = 10, K and L, n = 6, 3 male and 3 female; M, n = 3; *P < 0.05, unpaired 2-tailed Student’s t test.