Changes in retinal gene expression in proliferativevitreoretinopathy: glial cell expression of HB-EGF

[摘要] Purpose: To compare the gene expression pattern of controlpostmortem retinas with retinas from patients with proliferativevitreoretinopathy (PVR), to determine the expression of the heparinbinding epidermal growth factor-like growth factor (HB-EGF) by glialcells in fibroproliferative membranes, and to examine whether cells ofthe human Müller cell line, MIO-M1, respond to HB-EGF withproliferation, migration, and secretion of the vascular endothelialgrowth factor (VEGF).Methods: To identify genes that were differently expressed in PVRand control retinas, the RNA from the neural retinas of seven postmortemdonors and of two patients with PVR were analyzed for differential geneexpression, by hybridization of labeled cRNA probes to an Affymetrixhuman genome microarray set. The results were validated by real time PCRexperiments investigating RNA from 6 postmortem retinas and 4 PVRretinas. Epiretinal PVR membranes were immunohistochemically stained forcolocalization of HB-EGF and the glial cell marker, glial fibrillaryacidic protein (GFAP). The HB-EGF evoked proliferation of culturedMüller cells was investigated by a bromodeoxyuridine immunoassay,chemotaxis was assessed with a migration assay, and the release of VEGFwas evaluated by ELISA.Results: Out of the 12,600 genes and expressed sequence tagsinvestigated, the levels of 80 showed an increased expression, and 21were expressed at decreased levels, in the retinas of PVR patientscompared to the control retinas. The upregulated signals include genesfor nuclear and cell cycle related proteins, extracellular secretoryproteins, cytosolic signaling proteins, and proteins of the membrane andthe extracellular matrix. The genes of the hepatocyte growth factor andof HB-EGF were found to be expressed in PVR retinas but not in controlretinas. In epiretinal membranes of patients with PVR, HB-EGFimmunoreactivity partially colocalized with GFAP. In cultured Müllercells, HB-EGF stimulated both proliferation and chemotaxis, and thesecretion of VEGF, via activation of the extracellular signal regulatedkinases 1 and 2 and of the phosphatidylinositol-3 kinase.Conclusions: The development of PVR is accompanied by complexchanges of the gene expression in the neural retina, with anupregulation of genes that support cell proliferation, cell signaling,cell motility, and extracellular matrix remodeling. HB-EGF is one of thefactors that are significantly upregulated in PVR retinas. HB-EGFexpression in fibroproliferative tissue and its stimulatory effect onglial cell proliferation, chemotaxis, and VEGF secretion suggest thatHB-EGF may be a factor mediating glial cell responses during PVR.

[学科分类] 生物化学/生物物理