Lfng

LFNG, also known as Lunatic fringe, is a human gene encoding a member of the Fringe family of glycosyltransferases. Fringe enzymes are type II transmembrane proteins localized to the Golgi apparatus and are conserved from Drosophila to vertebrates. They catalyze the addition of N-acetylglucosamine to O-fucose residues on epidermal growth factor-like repeats of the Notch receptor, modifying Notch signaling outcomes.

In mammals, there are three Fringe homologs: LFNG (Lunatic fringe), MFNG (Manic fringe), and RFNG (Radical fringe). The Fringe enzymes alter the glycosylation state of Notch receptors, thereby biasing receptor activity toward responses to certain ligands, such as Delta-like versus Jagged. This modulation influences context-dependent Notch signaling across various tissues.

LFNG expression is dynamic during development and in adult tissues, consistent with roles in processes governed by Notch signaling. The gene and its family members contribute to tissue patterning and cell fate decisions in systems including the developing somites, nervous system, and vasculature. In experimental models, loss or misregulation of LFNG perturbs Notch-dependent developmental events, underscoring the significance of Fringe-mediated glycosylation in signaling specificity.

Beyond development, LFNG and related Fringe genes have been examined in the context of disease, where altered Notch signaling can contribute to developmental disorders and cancer in certain contexts. The name Fringe originates from the Drosophila gene that first revealed this class of glycosyltransferases, with vertebrate LFNG representing the functional vertebrate homolog.