title: Integrin-linked kinase deletion in the developing lens leads to capsule rupture, impaired fiber migration and non-apoptotic epithelial cell death.
abstract: OBJECTIVE
  The lens is a powerful model system to study integrin-mediated cell-matrix interaction in an in vivo context, as it is surrounded by a true basement membrane, the lens capsule. To characterize better the function of integrin-linked kinase (ILK), we examined the phenotypic consequences of its deletion in the developing mouse lens.
  
  
  METHODS
  ILK was deleted from the embryonic lens either at the time of placode invagination using the Le-Cre line or after initial lens formation using the Nestin-Cre line.
  
  
  RESULTS
  Early deletion of ILK leads to defects in extracellular matrix deposition that result in lens capsule rupture at the lens vesicle stage (E13.5). If ILK was deleted at a later time-point after initial establishment of the lens capsule, rupture was prevented. Instead, ILK deletion resulted in secondary fiber migration defects and, most notably, in cell death of the anterior epithelium (E18.5-P0). Remarkably, dying cells did not stain positively for terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) or activated-caspase 3, suggesting that they were dying from a non-apoptotic mechanism. Moreover, cross to a Bax(fl/fl)/Bak⁻/⁻ mouse line that is resistant to most forms of apoptosis failed to promote cell survival in the ILK-deleted lens epithelium. Electron microscopy revealed the presence of numerous membranous vacuoles containing degrading cellular material. CONCLUSIONS. Our study reveals a role for ILK in extracellular matrix organization, fiber migration, and cell survival. Furthermore, to our knowledge we show for the first time that ILK disruption results in non-apoptotic cell death in vivo.
authors.affiliation: Department of Ophthalmology, University of California, San Francisco, CA, USA.
authors.forename: Laura
authors.initials: L
authors.lastname: Cammas
authors.forename: Jordan
authors.initials: J
authors.lastname: Wolfe
authors.forename: Sue-Yeon
authors.initials: SY
authors.lastname: Choi
authors.forename: Shoukat
authors.initials: S
authors.lastname: Dedhar
authors.forename: Hilary E
authors.initials: HE
authors.lastname: Beggs
mesh_terms: D000818:Animals; D057866:Anterior Capsule of the Lens / Q000293:injuries / Q000473:pathology; D015820:Cadherins / Q000378:metabolism; D016923:Cell Death / Q000235:genetics / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D024141:Collagen Type IV / Q000378:metabolism; D004847:Epithelial Cells / Q000473:pathology*; D004848:Epithelium / Q000378:metabolism; D005136:Eye Proteins / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism; D017353:Gene Deletion; D018398:Homeodomain Proteins / Q000378:metabolism; D007797:Laminin / Q000378:metabolism; D007903:Lens Capsule, Crystalline / Q000196:embryology* / Q000293:injuries / Q000473:pathology*; D051379:Mice; D008822:Mice, Transgenic; D008854:Microscopy, Electron; D046529:Microscopy, Electron, Transmission; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D012421:Rupture; D015854:Up-Regulation; D014617:Vacuoles / Q000473:pathology; D000099200:Scaffold Protein ILK
chemical_list: D015820:Cadherins; D024141:Collagen Type IV; D005136:Eye Proteins; D005353:Fibronectins; D018398:Homeodomain Proteins; D007797:Laminin; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D017346:Protein Serine-Threonine Kinases; D012097:Repressor Proteins; D000099200:Scaffold Protein ILK; C000605732:Pax6 protein, mouse