CD9 tetraspanin is the only egg membrane protein known to be essential for fertilization. To investigate its role, we have measured, on a unique acrosome reacted sperm brought in contact with an egg, the adhesion probability and strength with a sensitivity of a single molecule attachment. Probing the binding events at different locations of wild-type egg we described different modes of interact...

The stromal cell-derived factor-1 (SDF-1)/chemokine C-X-C receptor 4 (CXCR4) axis plays a critical role in homing and engraftment of hematopoietic stem/progenitor cells (HSCs) during bone marrow transplantation. To investigate the transcriptional regulation provided by this axis, we performed the first differential transcriptome profiling of human cord blood CD34(+) cells in response to short-t...

The tetraspan cell surface glycoprotein, CD9, has been implicated in cellular signaling during growth and differentiation in the hematopoietic and nervous systems. Because CD9 expression is induced early in development in sensory and sympathetic neuroblasts, we investigated the role of CD9 in neurite outgrowth. We plated dissociated cells from neonatal sympathetic ganglia on immobilized anti-CD...

Multinucleated giant cells, formed by the fusion of monocytes/macrophages, are features of chronic granulomatous inflammation associated with infections or the persistent presence of foreign material. The tetraspanins CD9 and CD81 regulate multinucleated giant cell formation: soluble recombinant proteins corresponding to the large extracellular domain (EC2) of human but not mouse CD9 can inhibi...

Myeloma tumor cells, both freshly excised and cultured, are extremely resistant to cell-mediated cytolysis. As evidence suggests that B-cell susceptibility to lysis is dependent upon its state of differentiation and activation, we tested the ability of a variety of B-cell proliferation and differentiation agents, including pokeweed mitogen (PWM), to enhance the sensitivity of myeloma cells to c...

Metastasis-suppressing gene product CD82 and its analogue CD9 are considered to suppress the malignancy of various human cancers, although the rationale for this effect is unknown. The present study addresses phenotypic changes in Chinese hamster ovary mutant cell line ldlD deficient in UDP-Glc 4-epimerase and expressing CD82 or CD9 by cDNA transfection. Only CD82- or CD9-expressing cells grown...

Tetraspanin-29 (CD9) is an integral membrane protein involved in several fundamental cell processes and in cancermetastasis. Here, characterization of a panel of breast cancer cells revealed a nuclear pool of CD9, not present in normal human mammary epithelial cells. Antibody binding to surface CD9 of breast cancer cells resulted in increased nuclear CD9 fluorescence. CD9 was also found, along ...

Tetraspanins serve as molecular organizers of multiprotein microdomains in cell membranes. Hence to understand functions of tetraspanin proteins, it is critical to identify laterally interacting partner proteins. Here we used a novel technical approach involving exposure and cross-linking of membrane-proximal cysteines coupled with LC-MS/MS protein identification. In this manner we identified n...

The well documented source for adult multipotent stem cells is spermatogonial stem cells (SSCs) of mammalian testis. It is foundation of spermatogenesis in the testis throughout adult life by balancing self-renewal and differentiation. SSCs isolation from mammalian testis is difficult because of their scarcity and the lack of well characterized cell surface markers. Thus, the isolation of SSCs ...

Acquisition of fertilization ability by spermatozoa during epididymal transit occurs in part by the transfer of molecules from membranous vesicles called epididymosomes. Epididymosomes are heterogeneous in terms of both size and molecular composition. Exosomes and other related small membranous vesicles (30-120 nm) containing tetraspanin proteins on their surface are found in many biological fl...