Ichthyin Background Information Ichthyin (ICHN) is a 466 amino acid protein that is highly expressed in brain, lung, stomach, keratinocytes and leukocytes, and is localized to the cellular membrane as a multi-pass membrane protein. Ichthyin is expressed as two isoforms and is thought to possibly be a membrane receptor for the hepoxilin pathway. An ortholog of Ichthyin in Drosophila melanogaster is spichthyin (Spict). In the event that Spict is not functional, bone morphogenetic protein (BMP) signaling is upregulated and expansion of the neuromuscular junction occurs. Spict is thought to inhibit BMP signaling and the upregulation of BMP is thought to be associated with autosomal recessive congenital ichthyosis (ARCI). ARCI is a group of skin disorders varying in severity and phenotypes and the association between genotype and phenotype is not well understood in patients with ARCI. Non-bullous congenital ichthyosiform erythroderma (NCIE) is a phenotype of ARCI which is common in the event that the gene encoding Ichthyin is mutated. As a possible ligand receptor for the hepoxilin pathway, Ichthyin’s ligand–receptor interactions may be a potential target for treatment of dry skin.
