HRH4
Description
The HRH4 (histamine receptor H4) is a protein-coding gene located on chromosome 18.
The histamine H4 receptor, like the other three histamine receptors, is a member of the G protein-coupled receptor superfamily that in humans is encoded by the HRH4 gene. Unlike the histamine receptors discovered earlier, H4 was found in 2000 through a search of the human genomic DNA data base. H4 is highly expressed in bone marrow and white blood cells and regulates neutrophil release from bone marrow and subsequent infiltration in the zymosan-induced pleurisy mouse model. It was also found that H4 receptor exhibits a uniform expression pattern in the human oral epithelium. The Histamine H4 receptor has been shown to be involved in mediating eosinophil shape change and mast cell chemotaxis. This occurs via the βγ subunit acting at phospholipase C to cause actin polymerization and eventually chemotaxis. The histamine H4 receptor has been identified as a vital regulator of the immune system, involved in eosinophil migration, mast cell recruitment, dendritic cell activation, and T cell differentiation. The discovery of this receptor has brought it to increasing attention for its therapeutic use in inflammatory diseases such as allergy, asthma, chronic itch, and autoimmune diseases. The 3D structure of the H4 receptor has not been solved yet due to the difficulties of GPCR crystallization. Some attempts have been made to develop structural models of the H4 receptor for different purposes.
HRH4 is also known as AXOR35, BG26, GPCR105, GPRv53, H4, H4R, HH4R.
