The Epilepsy Gene LGI1 Encodes a Secreted Glycoprotein That Binds to the Cell Surface

Hum Mol Genet. 2006 Dec 1;15(23):3436-45. doi: 10.1093/hmg/ddl421. Epub 2006 Oct 26.

Abstract

Autosomal dominant lateral temporal epilepsy (ADTLE) is a partial epilepsy caused by mutations in LGI1, a multidomain protein of unknown function. To begin to understand the biological function of LGI1, we have determined its pattern of glycosylation, subcellular expression and capacity for secretion. LGI1 is expressed as two different isoforms in the brain, and we show that the long isoform is a secreted protein, whereas the short isoform is retained in an intracellular pool. ADLTE-related mutants of the long form are defective for secretion and are retained in the endoplasmic reticulum and Golgi complex. Finally, we show that normal secreted LGI1 specifically binds to the cell surface of differentiated PC12 cells. We propose that LGI1 is a secreted factor important for neuronal development and that ADTLE is a disease that results from the loss of regulation in the protein available either extracellular or intracellularly.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Membrane / chemistry
  • Cells, Cultured
  • Enzyme Activation
  • Epilepsy, Temporal Lobe / genetics*
  • Glycoproteins / analysis
  • Glycoproteins / genetics
  • Glycoproteins / metabolism*
  • Glycosylation
  • Humans
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • PC12 Cells
  • Protein Isoforms / analysis
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • Protein Structure, Tertiary / genetics
  • Protein Structure, Tertiary / physiology
  • Proteins / analysis
  • Proteins / genetics*
  • Proteins / metabolism*
  • Rats

Substances

  • Glycoproteins
  • LGI1 protein, human
  • Protein Isoforms
  • Proteins
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3