Altered susceptibility to apoptosis and N-glycan profiles of hematopoietic KG1a cells following co-culture with bone marrow-derived stromal cells under hypoxic conditions

Mesenchymal stromal cells are an important component of the bone marrow microenvironment (niche), where they support hematopoiesis via direct cell-cell interactions with hematopoietic stem and progenitor cells, and by releasing soluble factors. Glycans, including N-glycans, are involved in numerous biological processes, including inflammation, cell-cell interactions, as well as cancer development and progression. Lectin-based microarray analysis has provided a powerful new tool in recent years, for the investigation of aberrantly expressed N-glycans and their functions in the bone marrow microenvironment. In the present study, we used an in vitro stromal/hematopoietic cell co-culture system to examine the effects of stromal-derived signals on apoptosis susceptibility of co-cultured KG1a hematopoietic cells under hypoxic (1% O-2) conditions. MALDI-TOF/TOF-MS analysis was used for the comparative global profiling of N-glycans in KG1a cells and co-cultured KG1a cells under hypoxia. KG1a cells became more susceptible to p53-dependent apoptosis when co-cultured with HS27A human stromal cells (derived from normal bone marrow) under hypoxia. We observed enhanced levels of core-fucosylated N-glycans (catalyzed by FUT8), bisecting GlcNAc (catalyzed by MGAT3), and their corresponding genes in co-cultured cells. In addition we observed that overexpressing MGAT3 or FUT8 facilitated cell apoptosis in KG1a cells. Collectively, our data revealed the profiling of N-glycans in KG1a cells before and after stroma contact. Our findings and future functional studies of core-fucosylated N-glycans and bisecting GlcNAc, will improve our understanding of the bone marrow microenvironment.