Effects of semaphorin 4D in the immune system mediated by plexin receptors

Plexins are proteins that serve as receptors for molecules of the semaphorin family, including IV class semaphoring Sema4D.The plexin receptors mediate the key effects of Sema4D in the body, such as axonal targeting and stimulation of angiogenesis. For a long time it was believed that the expression of plexins was limited to non-immune tissues, whereas in the immune system Sema4D implements its effects through the membrane molecule CD72. However, in a number of papers has been shown the presence of plexin receptors for Sema4D on the membrane of immune cells. Therefore, they should be involved in mediating the immunoregulatory effects of Sema4D. This review is devoted to the analysis of data on the main functions of plexin receptors for Sema4D in the immune system and the mechanisms for realizing the plexin-dependent effects of this semaphorin in immune cells.