title: Experimental glaucoma and optic nerve transection induce simultaneous upregulation of proapoptotic and prosurvival genes.
abstract: OBJECTIVE
  To investigate changes in gene expression induced by elevated intraocular pressure (IOP) and complete optic nerve transsection (ONT) over time.
  
  
  METHODS
  A gene array of 18 signal transduction pathways was used to examine the changes in RNA profiles of retinas post-ONT in rats. Among the seven genes that were determined to be upregulated, four were confirmed to have higher expression by semiquantitative RT-PCR analysis: Ei24 and Gadd45a (both associated with apoptosis induced via the p53 pathway), IAP-1 (inhibitor of apoptosis protein 1), and Cdk2 (cell cycle regulation and apoptosis). Their mRNA levels were then studied by quantitative RT-PCR in experimental glaucoma and ONT over time. Levels of the corresponding proteins were evaluated by Western blot analysis and immunohistochemistry.
  
  
  RESULTS
  Proapoptotic genes from the p-53 pathway (Ei24 and Gadd45a), Cdk2 and the prosurvival gene IAP-1 (a caspase inhibitor) were simultaneously and significantly upregulated early after ONT, returning to baseline at 2 weeks. In experimental glaucoma, Gadd45a was significantly upregulated 1 week after induction of increased IOP and stayed upregulated for 2 months and long after IOP returned to baseline. The prosurvival gene IAP-1 was simultaneously upregulated but returned to baseline earlier than the proapoptotic gene. Ei24 and Cdk2 were only slightly upregulated in glaucoma. Western blot analysis demonstrated upregulation of Gadd45a and IAP-1 proteins. Immunohistochemistry localized these changes to the retinal ganglion cell layer.
  
  
  CONCLUSIONS
  Members of the p-53 signal transduction pathway are significantly involved in glaucoma and ONT. The endogenous caspase inhibitor IAP-1 is upregulated simultaneously, possibly as part of an intrinsic neuroprotective mechanism. Changes in glaucoma are gradual and last long after IOP returns to normal.
authors.affiliation: Sam Rothberg Ophthalmic Molecular Biology Laboratory, Goldschleger Eye Institute, Sheba Medical Center, Tel-Hashomer, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel. hani.verbin@sheba.health.gov.il
authors.forename: Hani
authors.initials: H
authors.lastname: Levkovitch-Verbin
authors.forename: Rima
authors.initials: R
authors.lastname: Dardik
authors.forename: Shelly
authors.initials: S
authors.lastname: Vander
authors.forename: Yael
authors.initials: Y
authors.lastname: Nisgav
authors.forename: Maya
authors.initials: M
authors.lastname: Kalev-Landoy
authors.forename: Shlomo
authors.initials: S
authors.lastname: Melamed
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D015153:Blotting, Western; D061945:Caspase Inhibitors; D002470:Cell Survival / Q000235:genetics*; D004195:Disease Models, Animal; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000502:physiology*; D005901:Glaucoma / Q000235:genetics*; D007150:Immunohistochemistry; D051034:Inhibitor of Apoptosis Proteins / Q000378:metabolism; D007429:Intraocular Pressure; D020221:Optic Nerve Injuries / Q000235:genetics*; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000235:genetics*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D061945:Caspase Inhibitors; D051034:Inhibitor of Apoptosis Proteins; D016159:Tumor Suppressor Protein p53