LFNG O-fucosylpeptide 3-beta-N-acetylglucosaminyltransferase, also known as LFNG and Lunatic Fringe, is a human gene.
This gene encodes a member of the glycosyltransferase superfamily. The encoded protein is a single-pass type II Golgi membrane protein that functions as a fucose-specific glycosyltransferase, adding an N-acetylglucosamine to the fucose residue of a group of signaling receptors involved in regulating cell fate decisions during development. Mutations in this gene have been associated with autosomal recessive spondylocostal dysostosis 3. Alternatively spliced transcript variants that encode different isoforms have been described, however, not all variants have been fully characterized.
Lunatic Fringe (Lfng) is a gene whose role in embryonic development is to establish the anterior boundary of somites, which will eventually develop in vertebrae, ribs, and dermis. Lunatic Fringe responds to certain threshold ratios of retinoic acid and FGF-8 in order to mark the anterior boundary of somites while another transcription factor, Hairy, responds to different threshold ratios of retinoic acid and FGF-8 to form the posterior boundaries of somites.
A defect associated with Lfng mutations is spondylocostal dysostosis. Spondylocostal dysostosis is characterized by segmentation problems in the developing vertebrae resulting in fusion or lack of vertebrae along with abnormalities in the ribs. Clinically, spondylocostal dysostosis presents as a shortened neck and trunk relative total height and a mild form of scoliosis. Respiratory problems are also common in spondylocostal dysostosis because of the shortened trunk.
A knockout model for Lfng has been created in mice, and without Lfng, mice have shorter tails, and impaired rib, lung, and somite development. A deficiency of Lfng in male mice has also been associated with lack of spermatozoa in the epididymis of many mice; however, spermatogenesis was not impaired. Rather, the male mice were subfertile. In female mice, Lfng deficiency led to infertility because of abnormal folliculogenesis. Further examination showed that oocytes from these female mice did not complete meiotic maturation. However, there are other studies that contradict this stating that not all female mile deficient of Lfng are infertile. A possible explanation for this difference between these studies is that the Lfng alleles were functional different, however, this is unlikely. More likely is that this discrepancy results from differences in the genetic background of the mice or husbandry and colony conditions.
^Shifley ET, Vanhorn KM, Perez-Balaguer A, Franklin JD, Weinstein M, Cole SE (2008). "Oscillatory lunatic fringe activity is crucial for segmentation of the anterior but not posterior skeleton". Development. 135 (5): 899–908. doi:10.1242/dev.006742. PMID18234727.
^Hahn KL, Beres B, Rowton MJ, Skinner MK, Chang Y, Rawls A, Wilson-Rawls J (2009). "A deficiency of lunatic fringe is associated with cystic dilation of the rete testis". Reproduction. 137 (1): 79–93. doi:10.1530/REP-08-0207. PMID18801836.
^Hahn KL, Johnson J, Beres BJ, Howard S, Wilson-Rawls J (2005). "Lunatic fringe null female mice are infertile due to defects in meiotic maturation". Development. 132 (4): 817–28. doi:10.1242/dev.01601. PMID15659488.
^Xu J, Norton CR, Gridley T (2006). "Not all lunatic fringe null female mice are infertile". Development. 133 (4): 579; author reply 579–80. doi:10.1242/dev.02221. PMID16436621.
Johnston SH, Rauskolb C, Wilson R, Prabhakaran B, Irvine KD, Vogt TF (1997). "A family of mammalian Fringe genes implicated in boundary determination and the Notch pathway". Development. 124 (11): 2245–54. PMID9187150.
Moran JL, Johnston SH, Rauskolb C, Bhalerao J, Bowcock AM, Vogt TF (June 1999). "Genomic structure, mapping, and expression analysis of the mammalian Lunatic, Manic, and Radical fringe genes". Mamm. Genome. 10 (6): 535–41. doi:10.1007/s003359901039. PMID10341080.
Moloney DJ, Panin VM, Johnston SH, Chen J, Shao L, Wilson R, Wang Y, Stanley P, Irvine KD, Haltiwanger RS, Vogt TF (2000). "Fringe is a glycosyltransferase that modifies Notch". Nature. 406 (6794): 369–75. doi:10.1038/35019000. PMID10935626.
Shimizu K, Chiba S, Saito T, Kumano K, Takahashi T, Hirai H (2001). "Manic fringe and lunatic fringe modify different sites of the Notch2 extracellular region, resulting in different signaling modulation". J. Biol. Chem. 276 (28): 25753–8. doi:10.1074/jbc.M103473200. PMID11346656.
Shao L, Moloney DJ, Haltiwanger R (2003). "Fringe modifies O-fucose on mouse Notch1 at epidermal growth factor-like repeats within the ligand-binding site and the Abruptex region". J. Biol. Chem. 278 (10): 7775–82. doi:10.1074/jbc.M212221200. PMID12486116.
Oh JH, Yang JO, Hahn Y, Kim MR, Byun SS, Jeon YJ, Kim JM, Song KS, Noh SM, Kim S, Yoo HS, Kim YS, Kim NS (2005). "Transcriptome analysis of human gastric cancer". Mamm. Genome. 16 (12): 942–54. doi:10.1007/s00335-005-0075-2. PMID16341674.