Abstract
Purpose::
To identify the molecular mechanisms by which CNTF, BDNF, and FGF-2 mediate retinal neuroprotection. At the previous ARVO we reported Initial results (ARVO 2006) included identification of several genes that were up-regulated by all 3 factors 6 and 48 hours after intravitreal injection. Immunohistochemistry localized some of the early-induced molecules to Müller glia, macrophage-like cells and/or astrocytes. Building on those findings, we performed additional transcriptional profiling for the 24 hour post-injection time point, and selected a group of genes for more detailed expression studies, with multiple biological replicates and expanded time-course analysis.
Methods::
Adult, wild type C57BL/6J mice received an intravitreal injection of 1ug/ul of either CNTF, BDNF, FGF-2 or vehicle. Animals were sacrificed 1, 6, 12, 24, 48 hours or 1 week post-injection for real time PCR (QPCR), or microarray analysis. RNA harvesting, QPCR and Affymetrix microarray analysis (MOE430_2) were performed by standard methods.
Results::
Microarray analysis of retinal samples 6, 24 and 48 hours post-injection identified several groups of molecules that were up-regulated by growth factors and could be potentially involved in mediating photoreceptor rescue. Among these were: 1) molecules whose mutation is associated with retinopathy (chemokine (C-C motif) ligand 2, dystrophin); 2) neuronal survival promoting factors (endothelin 2, interleukin 6, leukemia inhibitory factor); 3) growth factor receptors and modulators (oncostatin M receptor, suppressor of cytokine signaling; 4) interferon-induced molecules (interferon-induced transmembrane protein 3); 5) transcription factors (C/EBP delta, signal transducer and activator transcript 3); and 6) ion regulating molecules (ceruloplasmin, transferrin, lipocalin 2, metallothionein 2). QPCR showed characteristic time-courses of induction for different members of these families of molecules.
Conclusions::
Analysis of genes modulated by the intravitreal injection of CNTF, BDNF, and FGF-2 suggest the involvement of membrane stabilization, immunoregulation, and cytoskeletal modulation in growth factor-mediated retinal neuroprotection.
Keywords: cytokines/chemokines • growth factors/growth factor receptors • neuroprotection