C‑mannosylation of R‑spondin2 activates Wnt/β‑catenin signaling and migration activity in human tumor cells

Abstract

, one of the four members of the R-spondin family of proteins, has agonistic activity in the Wnt/β-catenin signaling pathway, and it is associated with normal development, as well as disease, such as cancer. The present study focused on the C-mannosylation of Rspo2, which is a novel and unique type of glycosylation that occurs via a C-C linkage between the tryptophan residue and an α-mannose. Although Rspo2 has two putative C-mannosylation sites at residues Trp 150 and Trp 153 , it had not been reported to date whether these sites are C-mannosylated. Firstly, results from mass spectrometry demonstrated that Rspo2 was C-mannosylated at the Trp 150 and Trp 153 residues. Notably, while this C-mannosylation of Rspo2 resulted in increased extracellular secretion in human fibrosarcoma HT1080 cells, in other human tumor cell lines it inhibited secretion. However, C-mannosylation had consistent effects on the activation of Wnt/β-catenin signaling in PANC1 and MDA-MB-231 cells, as well as HT1080 cells. Furthermore, overexpression of wild-type Rspo2 significantly increased the migratory ability of A549 and HT1080 cells, whereas overexpression of a C-mannosylation-defective mutant enhanced migration to a lesser degree. These results suggested that C-mannosylation of Rspo2 may promote cancer progression and that the inhibition of C-mannosylation may serve as a potential novel therapeutic approach for cancer therapy.

Involvement of DPY19L3 in Myogenic Differentiation of C2C12 Myoblasts

“…There are four homologs of DPY19 (DPY19L1-L4) in mammals, and it has been demonstrated that DPY19L1 and DPY19L3 have a C -mannosyltransferase activity [ 11 , 12 ]. It has been revealed that C -mannosylation involves protein secretion, intracellular localization, and protein folding, which are similar with other forms of glycosylation [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ]; however, the role of C -mannosyltransferases on biological events is still obscured.…”

Protein C-Mannosylation and C-Mannosyl Tryptophan in Chemical Biology and Medicine

“…Secretion of C -mannosylation-defective mutants of R-spondin2 was reduced in human fibrosarcoma HT1080, whereas its secretion was increased in other human tumor cell lines, such as A549, PANC1, and MDA-MB-231 [ 65 ]. Thus, the secretion of R-spondin2 was different among tumor cell lines, indicating that the effect of C -mannosylation on R-spondin2 secretion may differ in a cell type-dependent manner.…”

“…C -Mannosylation of R-spondin1, 2, and 3 enhanced Wnt/β-catenin activation [ 62 , 63 , 65 ]. C -Mannosylation was also involved in the regulation of JAK-STAT signaling through effects on TPOR [ 72 ] or G-CSFR [ 73 ].…”

“…As described above, C -Man-Trp is produced in part by degradation of C -mannosylated proteins through the autophagic pathway in cells [ 91 ]. On the other hand, it was reported that C -mannosylation of R-spondin2 is involved in the promotion of cancer cell migration in various human tumor cells, suggesting a pathological correlation between protein C -mannosylation and tumor progression [ 65 ]. Thus, it is of interest to investigate the correlation of altered expression of C -mannosylated proteins and upregulated production of monomeric C -Man-Trp in cancer tissues.…”

C‑Mannosyl tryptophan increases in the plasma of patients with ovarian cancer

“…In regard to human health and protein C-mannosylation, it was reported that blood CMW is elevated in patients with renal dysfunction, including renal diseases associated with type 2 diabetes (17–21). As for cancer biology, it was recently reported that C-mannosylation of R-spondin 2 activates Wnt/β-catenin signaling and migration activity in various human tumor cells (22). This study suggested that C-mannosylation of R-spondin 2 is involved in the promotion of cancer progression.…”