Abstract
Purpose: :
ADAMTSL4
Methods: :
ADAMTSL4 cDNA was cloned in a pcDNA3.1A vector in-frame with a C-terminal Myc+6XHis tag and transfected into HEK293F cells to characterize the recombinant protein. ADAMTSL4 polyclonal Ab was characterized by immunoblotting of medium and the cell lysate, and comparison with anti-Myc Ab. Extracted protein from different structures in healthy human eye tissue was analyzed by western blotting with ADAMTSL4 Ab, and immunoperoxidase staining of sections of normal and Marfan syndrome human eyes were performed to determine the ocular distribution of ADAMTSL4. To check whether ADAMTSL4 influenced FBN-1 deposition in extracellular matrix, we used a functional assay in which fetal bovine nuchal ligament cells (FBNLC) were incubated with medium containing ADAMTSL4 or a control medium, and FBN-1 immunofluorescence was done to evaluate FBN-1 deposition.
Results: :
ADAMTSL4 cDNA sequence predicts a core protein of 140 kDa with substantial N-glycosylation. Western blotting of recombinant protein with ADAMTSL4 Ab showed a major band of 150 kDa in ADAMTSL4-transfected but not vector-transfected cells, similar to results with anti-Myc Ab. By tissue western blotting, ADAMTSL4 protein was detected in the uveal tract, lens capsule, zonule fibers, cornea, and retina. Immunoperoxidase staining of one healthy eye and one Marfan syndrome eye showed primarily a fibrillar, extracellular staining in most components of the eye, and was not restricted to the zonular apparatus. In the presence of ADAMTSL4-containing medium, FBNLC showed enhanced FBN-1 deposition compared with the control.
Conclusions: :
ADAMTSL4 is a secreted glycoprotein that is widely distributed in the human eye including regions where the zonular apparatus is assembled. Our in vitro data demonstrating enhanced FBN-1 deposition in the presence of ADAMTSL4 suggest a role in the interaction of these proteins in the assembly of the zonule.
Keywords: extracellular matrix • anterior segment • genetics