Tetraspanin protein CD9 interacts with metalloprotease CD10 and enhances its release via exosomes

Abstract

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.

KAI1/CD82 and MRP1/CD9 Serve as Markers of Infiltration, Metastasis, and Prognosis in Laryngeal Squamous Cell Carcinomas

“…KAI1 gene products interconnect with other TM4SF members (Zoller, 2006). CD9, CD63, and CD82 interlink with each other and bind with integrins to form complexes, whereby to regulate the adhesion function of the integrins and influence cell transfer medicated by them (Ono et al, 1999, Mazurov et al, 2013. KAI1/CD82 and MRP1/CD9 cDNA transfection greatly reduces the locomotivity of KAI1/CD82 or MRP1/CD9 expressed ovarian mutant cells and causes the necrosis of most of them, which indicates that the common glycosylation of KAI1/CD82 and MRP1/CD9 inhibits cell movement and necrosis (Shibagaki et al, 1999).…”

Exosome mediated communication within the tumor microenvironment

“…The early endosome has receptors that can facilitate the encapsulation of cytosolic components; for example, tetraspanins have been demonstrated to facilitate the incorporation of specific cargo into exosomes. Tetraspanin CD9 has been shown to mediate exosomal loading of the metalloproteinase CD10 while CD63 has been shown to control the loading of LMP1 Epstein-Barr virus protein into exosomes [30][31][32]. Likewise, the lipid composition of the early endosome and MVB as well as membrane dynamics have been shown to govern exosomal content.…”

“…Through signaling interactions, endosomal constituents can determine exosome content. For example, a study examining the interaction between the tetraspanin protein CD9 and the metalloprotease CD10 demonstrated that CD9 controls the loading of CD10 into exosomes [30]. The study used K562 erythromyeloid cells that have a low level of basal CD9 expression, transfected the cells with a plasmid conferring CD10 expression and neomycin resistance via a lentiviral vector and selected for CD10 expressing (neomycin resistant) cells [30].…”

Post-translational add-ons mark the path in exosomal protein sorting

“…Such mechanisms do exist. In these, sorting depends on tetraspanins, sphingolipids and ceramide [58][59][60]. For example, LYPX(n)L motifs in the protein ALIX are implicated in its interaction with CD63 tetraspanin, and together with transmembrane proteins syndecans and syntenin induce budding and membrane abscission of ILVs [61].…”