Pathobiology of epiretinal and subretinal membranes: possible roles for the matricellular proteins thrombospondin 1 and osteonectin (SPARC).
Epiretinal and subretinal membranes are fibrocellular proliferations which form on the surfaces of the neuroretina as a sequel to a variety of ocular diseases. When these proliferations complicate rhegmatogenous retinal detachment (a condition known as proliferative vitreoretinopathy or PVR), the membranes often contain numerous retinal pigment epithelial (RPE) cells and a variety of extracellular proteins. The extracellular proteins include adhesive proteins like collagen, laminin and fibronectin. In addition, several matricellular proteins with potential counter-adhesive functions are present in the membranes. Two such matricellular proteins, thrombospondin 1 and osteonectin (or SPARC: Secreted Protein Acidic and Rich in Cysteine), tend to be co-distributed with the RPE cells in PVR membranes. By virtue of their counter-adhesive properties, thrombospondin 1 and SPARC may reduce RPE cell-matrix adhesion and so permit key RPE cellular activities (for example, migration or shape change) in periretinal membrane development. Furthermore, within a 'cocktail' containing other proteins such as the metalloproteinases and growth factors like the scatter factor/hepatocyte growth factor family, matricellular proteins may play a role in the RPE cell dissociation from Bruch's membrane, which characterises early PVR.
Hiscott
P
P
Unit of Ophthalmology Department of Medicine University of Liverpool Liverpool, UK. paulsh@liv.ac.uk
Hagan
S
S
Heathcote
L
L
Sheridan
C M
CM
Groenewald
C P
CP
Grierson
I
I
Wong
D
D
Paraoan
L
L
D019773:Epiretinal Membrane / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D015676:Osteonectin / Q000502:physiology*; D010857:Pigment Epithelium of Eye / Q000473:pathology; D019700:Thrombospondin 1 / Q000502:physiology*; D018630:Vitreoretinopathy, Proliferative / Q000378:metabolism*
D015676:Osteonectin; D019700:Thrombospondin 1