C-mannosylation promotes ADAMTS1 activation and secretion in human testicular germ cell tumor NEC8 cells

C-mannosylation is a protein glycosylation that regulates the functions of target proteins. Although it has been reported that a disintegrin and metalloproteinase with thrombospondin motifs 1 (ADAMTS1), an important spermatogenesis factor, is C-mannosylated, the roles of C-mannosylation in ADAMTS1 in testicular cells are still unclear. In this study, we found that ADAMTS1 is C-mannosylated at Trp⁵⁶² and Trp⁵⁶⁵ in testis germ NEC8 cells. To determine the roles of C-mannosylation in ADAMTS1, we established cells expressing a C-mannosylation-defective ADAMTS1, in which C-mannosylated tryptophan residues were replaced with phenylalanine residues (ADAMTS1/2WF). Processing and secretion of ADAMTS1/2WF were both inhibited compared to those of wild-type. Moreover, wild-type ADAMTS1 degraded aggrecan, whereas ADAMTS1/2WF could not. These results indicate the impact of C-mannosylation on ADAMTS1 function.