A family of structurally related growth and differentiation factors found in the central and peripheral nervous systems, which includes products of the Nrg1, Nrg2, Nrg3, and Nrg4 genes. NRG1, the most widely studied neuregulin, has 14 different isoforms, produced by alternative splicing of its mRNA, and 7 isoforms of NRG2 have been identified. A variety of proteins identified in various independent studies, including the neu differentiation factor (NDF), heregulin (HRG), glial growth factor 2 (GGF2), and acetylcholine receptor- inducing activity (ARIA), are all isoforms of NRG1, produced by alternatively spliced mRNA. All NRG1 isoforms have in common with each other and with other neuregulins an epidermal growth factor (EGF)-like sequence, which is essential for their function. Some neuregulins have in common a transmembrane domain, followed by a variable intracellular domain, while others differ from one another in their N-terminal domains. These structural features suggest functional similarities as well as distinctions between the neuregulin family members. NRGs interact with a family of receptor tyrosine kinases on target cells to influence a number of cellular processes, including the synthesis of acetylcholine receptors at neuromuscular junctions, the proliferation and survival of oligodendrocytes, and the proliferation and myelination of Schwann cells. Nrg1 is a candidate gene for schizophrenia (q.v.) and is also thought to be linked to age-related memory loss. See epidermal growth factor (EGF).
Subjects: Genetics and Genomics — Medicine and Health.