semaphorin4D

Semaphorin 4D (SEMA4D), also known as CD100, is a member of the class IV semaphorin family, a group of proteins primarily involved in axonal guidance, immune responses, and angiogenesis. SEMA4D is a transmembrane glycoprotein that can also be cleaved to produce a soluble form, enabling it to function in both cell-cell contact-dependent and -independent signaling pathways.

Originally identified in neurons, SEMA4D plays a critical role in the nervous system by guiding the development of nerve fibers during embryogenesis. It interacts with receptors such as plexins and neuropilins, triggering intracellular signaling cascades that influence cell migration, growth cone collapse, and apoptosis.

Beyond the nervous system, SEMA4D is expressed in various tissues, including immune cells such as T cells, B cells, and monocytes. In the immune system, it is involved in mediating immune cell activation, differentiation, and cytokine production. It also influences angiogenesis, the formation of new blood vessels, by interacting with endothelial cells, making it relevant in processes like wound healing and tumor progression.

Alterations in SEMA4D expression or signaling have been associated with various pathological conditions, including cancer, autoimmune diseases, and neurodegenerative disorders. Therapeutic strategies targeting SEMA4D are under investigation, aiming to modulate its function to treat certain cancers, inflammatory diseases, and neural injury.

Overall, Semaphorin 4D is a multifunctional protein critical for developmental and physiological processes, with significant implications for health and disease management.