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Tetraspanins interact with a wide variety of transmembrane and intracellular proteins called molecular partners, and modulate their function. In this article, we describe a new partner of tetraspanin web, membrane metalloprotease CD10, which is selectively associated with CD9. By constructing chimeras between tetraspanins CD9 and CD82 (the latter does not interact with CD10) or by using site-directed mutagenesis, we determined that a portion of the large extracellular loop from the CCG motif to transmembrane domain 4, as well as the C-terminal tail of CD9, are involved in the interaction with CD10. The stable expression of wild-type CD9 in K562 CD10-positive cells enhanced the level of CD10 released with exosomes five-fold. In contrast, the expression of chimeric CD9, which contained the cytoplasmic C-terminal domain from CD82, had little effect on CD10 release. Short hairpin RNA knockdown of CD9 expression in Nalm-6 pre-B cells resulted in a two-fold reduction in the amount of endogenous CD10 released with microvesicles. The peptidase activity of CD10 measured either on cells or on exosomes correlated with the level of CD10 expression, and was not significantly modulated by CD9 expression as such. Our data suggest that the interaction of CD10 with tetraspanin CD9 can play an important role in the redistribution of peptidase activity from the cell surface to outer microenvironments. In bone marrow, where CD10 presumably contributes to the maturation of pre-B cells and migration of B cells to the blood circulation, release of CD10 peptidase activity with exosomes may effectively regulate extracellular matrix microenvironments.
Structured digital abstract
- CD9 physically interacts with CD179b, Tetraspanin-9, CD63, CD81, HLA class II, Uncharacterized protein C14orf166B, Tetraspanin-14, HLA class I, Galactokinase, Protein disulfide-isomerase A6, CD98, CD19, CD316, CD146, CD92, Annexin A6, CD156c, CD71, CD10, CD29, CD315, DAAM1 and CD49f by anti bait coimmunoprecipitation (View interaction)
- CD10 physically interacts with CD9 by anti bait coimmunoprecipitation (View Interaction: 1, 2, 3, 4)
- CD10 physically interacts with CD179b, Protein FAM207A, CD9, CD81, Uncharacterized protein C22orf13, HLA class II, Uncharacterized protein C3orf26, HLA class I, Protein C14orf21, Annexin A6 and DAAM1 by anti bait coimmunoprecipitation (View interaction)