Abstract
Purpose: :
Aqueous humor outflow resistance is generated near the juxtacanalicular connective tissue and the inner wall endothelium of Schlemm’s canal (SC). Due to a basal-to-apical directed pressure drop across these tissues, we hypothesize that SC cells must strongly adhere to their basement membrane through function-specific laminin heterotrimers and their cognate integrins. The purpose of this study was to characterize the laminin and laminin-specific integrins in Schlemm’s canal basement membrane.
Methods: :
Frozen sagittal sections through conventional outflow tissues from human donor eyes were probed with antibodies recognizing several monomers of laminin (laminin α5, β1, γ1, α3, β3, γ2) and laminin-specific integrin pairs (integrin α3, α6, β1, β4). En-face preparations of SC’s inner wall from perfusion-fixed eyes were immunostained for laminin and integrin co-localization. All tissue samples were examined with confocal microscopy and compared to controls. Mature SC cell monolayers were prepared for immunoprecipitation and Western blot to examine specific laminin heterotrimers.
Results: :
In situ
Conclusions: :
Immunofluorescence, en-face imaging and Western blot show SC expression of LM-511 and integrin α6 in situ and in vitro. The patterned expression suggests that inner wall endothelia utilize integrin α6 to adhere to LM-511 in opposition to the force of basal-apical pressure gradient in vivo.
Keywords: extracellular matrix • cell adhesions/cell junctions • immunohistochemistry