The acetylglucosaminyltransferase GnT-Ⅲ regulates erythroid differentiation through ERK/MAPK signaling.

Differentiation therapy is an alternative strategy used in treating chronic myelogenous leukemia (CML) to induce the differentiation of immature or cancerous cells towards mature cells and inhibit tumor cell proliferation. We aimed to explore N-glycans' roles in erythroid differentiation using the sodium butyrate (NaBu)-induced model of K562 cells (WT/NaBu cells). Here, using lectin blot, flow cytometry, real-time PCR, and mass spectrometry analyses, we demonstrated that the mRNA levels of N-acetylglucosaminyltransferase Ⅲ (GnT-Ⅲ encoded by the MGAT3 gene) and its product (bisected N-glycans) were significantly increased during erythroid differentiation. To address the importance of GnT-Ⅲ in this progress, we established a stable MGAT3 knockout (KO) K562 cell line using the CRISPR/Cas9 technology. Compared to WT/NaBu cells, MGAT3 KO significantly impeded the progression of erythroid differentiation, as shown in decreased cell color and levels of erythroid markers, glycophorin A (CD235a), and β-globin. Consistently, MGAT3 KO mitigated the inhibitory impact of NaBu on cell proliferation. During induction, MGAT3 KO suppressed the cellular phosphorylated tyrosine and phospho-ERK1/2 levels. Inhibition of the ERK/MAPK signaling pathway using U0126 blocked erythroid differentiation while concurrently suppressing the expression levels of MGAT3 and bisected N-glycans. Furthermore, the lack of bisecting GlcNAc modification on c-Kit and transferrin receptor 1 (CD71) suppressed cellular signaling and accelerated the degradation of the CD71 protein, respectively. Our study highlights the critical role of MGAT3 in regulating erythroid differentiation associated with the ERK/MAPK signaling pathway, which may shed light on identifying new differentiation therapy in chronic myelogenous leukemia.