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Critical Reviews™ in Immunology

Impact factor: 3.889

ISSN Print: 1040-8401
ISSN Online: 2162-6472

Critical Reviews™ in Immunology

DOI: 10.1615/CritRevImmunol.v23.i12.40
17 pages

Structure and Function of the Immune Semaphorin CD100/SEMA4D

Abdellah Elhabazi
Department of Biology, Faculty of Sciences, El Jadida Morocco; Inserm U448, Creteil Faculty of Medicine, 94010 Creteil, France
Anne Marie-Cardine
Inserm U448, Creteil Faculty of Medicine, 94010 Creteil, France
Isabelle Chabbert-de Ponnat
Inserm U448, Creteil Faculty of Medicine, 94010 Creteil, France
Armand Bensussan
Inserm U448, Creteil Faculty of Medicine, 94010 Creteil, France
Laurence Boumsell
Inserm U448, Creteil Faculty of Medicine, 94010 Creteil, France

ABSTRACT

Semaphorins are a large family of membrane-bound and secreted molecules involved in numerous functions, including axon guidance, morphogenesis, carcinogenesis, and immunomodulation. A growing number of semaphorins—namely, human CD100/SEMA4D, CD108/SEMA7A, and SEMA3A; viral semaphorins, SemaVA and SemaVB; and, very recently, mouse Sema4A—were reported to regulate immune cell responses. Among them, the role of CD100 has been well documented in both humans and mice. CD100, in particular, has been shown to influence monocyte migration, T-cell activation, B-cell survival, as well as T/B and T/dendritic cell cooperation. In contrast to other semaphorins, CD100 is the only semaphorin for which membrane and soluble forms are endowed with functional properties, and for which bidirectional signaling has been suggested. The human membrane-bound CD100 engagement triggers costimulatory signals to T cells through its interaction with membrane protein tyrosine phosphatase CD45 and an intracellular serine kinase. Its soluble extracellular region acts most likely through its receptors, human PlexinB1 and mouse CD72, to promote T-cell priming, B-cell survival, and antibody production in response to T-dependent antigens. Human soluble CD100 also induces monocyte paralysis and the arrest of its spontaneous and chemokine-induced migration by signaling through an as yet unknown receptor that is different from PlexinB1 and CD72. In this review, we discuss recent advances in reseach studies on human and murine CD100, and we describe the relationship of CD100 function to its expression and Structure. The signaling events that support CD100 function are also discussed.