SEMA7A
Description
The SEMA7A (semaphorin 7A (JohnMiltonHagen blood group)) is a protein-coding gene located on chromosome 15.
SEMA7A, also known as CD108 (Cluster of Differentiation 108), is a human gene that encodes a membrane-bound semaphorin. It associates with cell surfaces through a glycosylphosphatidylinositol (GPI) linkage and is also recognized as the John-Milton-Hagen (JMH) blood group antigen. This 80-kD glycoprotein is expressed on activated lymphocytes and erythrocytes. SEMA7A is found in various adult tissues, including adipose, colon, esophagus, heart, brain, spleen, testis, lung, ovary, and uterus. SEMA7A plays a vital role in promoting axonal growth during development. It is involved in the formation of somites, which are blocks of mesoderm that give rise to vertebrae, ribs, and muscles. The highest expression of Sema7A in mice occurs on embryonic day 7, indicating its importance in germ layer differentiation. SEMA7A is expressed throughout embryonic development, as well as in the newborn and adult thymus, suggesting a role in T-cell development. In vitro experiments demonstrate that Sema7A promotes the elongation and branching of neurons in a dose-dependent manner. Unlike most semaphorins, SEMA7A enhances axonal growth and is essential for the proper formation of embryonic axonal tracts. While limited expression is found in the hindbrain, SEMA7A is abundantly expressed in both cranial and trunk neural crest cells, indicating its involvement in migration and differentiation. Mice lacking SEMA7A (Sema7A -/- mice) exhibit defects in olfactory tract development.
SEMA7A plays a crucial role in integrin-mediated signaling, influencing both cell migration and immune responses. It facilitates the formation of focal adhesion complexes, activates the protein kinase PTK2/FAK1, and subsequently triggers the phosphorylation of MAPK1 and MAPK3. SEMA7A also stimulates the production of pro-inflammatory cytokines by monocytes and macrophages, contributing to the modulation of inflammation and T-cell-mediated immune responses. In embryonic development, SEMA7A promotes axon growth in the olfactory bulb. It also enhances attachment, spreading, and dendrite outgrowth in melanocytes.
SEMA7A is also known as CD108, CDw108, H-SEMA-K1, H-Sema-L, JMH, PFIC11, SEMAK1, SEMAL.
