BMP-1-induced GBA1 nuclear accumulation provokes CCN2 mRNA expression via importin-β-mediated nucleocytoplasmic pathway

Bone morphogenetic protein (BMP)-1 is produced by odontoblasts within the dentin-pulp complex. While the functional effects of BMP-1 on the maturation of various proteins and enzymes essential for initiating mineralization have been extensively documented, its impact on cellular molecules remains unclear. We conducted a thorough analysis of glycome profiles altered by BMP-1 and subsequent assays to identify the target glycoproteins in human dental pulp cells (hDPCs) using a glycomic approach. In the presence of BMP-1, lectin microarray analysis and lectin-probed blotting revealed a significant reduction in α2,6-sialylation in insoluble fractions from hDPCs. Mass spectrometry identified six proteins among the α2,6-sialylated glycoproteins purified via a lectin column. Notably, glucosylceramidase (GBA1) was observed to accumulate in the nuclei of hDPCs in the presence of BMP-1. Additionally, the expression of cellular communication network factor (CCN) 2, a well-established marker of osteogenesis and chondrogenesis, was significantly inhibited in cells transfected with GBA1 siRNA. Importantly, importazole, a potent inhibitor of importin-β-mediated nuclear import, markedly suppressed both BMP-1-induced GBA1 nuclear accumulation and BMP-1-induced CCN2 mRNA expression. Therefore, BMP-1 promotes the nuclear accumulation of GBA1 by reducing α2,6-sialic acid, which may play a role in the transcriptional regulation of the CCN2 gene via the importin-β-mediated nuclear import pathway in hDPCs. Our findings provide new insights into the BMP-1-GBA1-CCN2 axis’s role in the development, tissue remodeling, and pathology of dental and craniofacial diseases.