title: Cadm1 expression and function in the mouse lens.
abstract: OBJECTIVE
  The immunoglobulin superfamily member Cadm1 is a single-pass, type 1 membrane protein that mediates calcium-independent, cell-cell adhesion. Cadm1 has been implicated in tumor formation and synaptogenesis. A recent analysis of mouse lens cell membranes identified Cadm1 as a major constituent of the fiber cell membrane proteome. Here the authors examined the expression and function of Cadm1 in the mouse lens.
  
  
  METHODS
  Cadm1 expression was analyzed by Western blotting and immunofluorescence. The morphology of individual wild-type and Cadm1-null lens cells was visualized by confocal microscopy.
  
  
  RESULTS
  Cadm1 was present in epithelial and superficial fiber cells as a heavily glycosylated protein with an apparent molecular mass of ≈80 kDa. Analysis of proteins extracted from various strata of the lens indicated that Cadm1 was degraded during fiber cell differentiation, at approximately the same time as the lens organelles, an observation confirmed by confocal microscopy. In epithelial cells, Cadm1 was enriched in basolateral membranes, whereas, in fiber cells, expression was restricted to the lateral membranes. Lenses from Cadm1-null mice were of normal size and transparency. The three-dimensional morphology of the cells in the epithelial layer was unaltered in the absence of Cadm1. However, in contrast to wild-type lens fiber cells, Cadm1-null fiber cells had an irregular, highly undulating morphology.
  
  
  CONCLUSIONS
  Cadm1 is an abundant component of the lens fiber cell membrane. Although not essential for lens transparency, Cadm1 has an indispensable role in establishing and maintaining the characteristic three-dimensional architecture of the lens fiber cell mass.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, USA.
authors.forename: Alicia
authors.initials: A
authors.lastname: De Maria
authors.forename: Yanrong
authors.initials: Y
authors.lastname: Shi
authors.forename: Xianmin
authors.initials: X
authors.lastname: Luo
authors.forename: Louise
authors.initials: L
authors.lastname: Van Der Weyden
authors.forename: Steven
authors.initials: S
authors.lastname: Bassnett
mesh_terms: D000818:Animals; D001485:Basement Membrane / Q000378:metabolism; D015153:Blotting, Western; D000075982:Cell Adhesion Molecule-1; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D004591:Electrophoresis, Polyacrylamide Gel; D019084:Fluorescent Antibody Technique, Indirect; D007136:Immunoglobulins / Q000235:genetics / Q000378:metabolism*; D007908:Lens, Crystalline / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D012333:RNA, Messenger / Q000235:genetics
chemical_list: C498598:Cadm1 protein, mouse; D000075982:Cell Adhesion Molecule-1; D015815:Cell Adhesion Molecules; D007136:Immunoglobulins; D012333:RNA, Messenger