Lithium treatment increases endothelial cell survival and autophagy in a mouse model of Fuchs endothelial corneal dystrophy
BRITISH JOURNAL OF OPHTHALMOLOGY
Authors: Kim, Eun Chul; Meng, Huan; Jun, Albert S.
Abstract
Background Lithium previously has been shown to reduce both endoplasmic reticulum (ER) and oxidative stress in other in vitro and in vivo model systems. We investigated lithium's effects on cultured corneal endothelial cells (CECs) exposed to these types of stress and in a mouse model of Fuchs endothelial corneal dystrophy (FECD). Methods Viability of cultured bovine CECs was determined by CellTiter-Glo. 2-month-old Col8a2(Q455K/Q455K) mutant (Q455K) and C57/Bl6 wild type animals were divided into two groups of 15 mice. Group I received 0.2% lithium carbonate-containing chow and Group II received control chow for 7months. Confocal microscopy, transmission electron microscopy, real-time PCR (RT-PCR) and western blot were performed. Results Pretreatment with lithium increased viability of cultured CECs after H2O2 and thapsigargin exposure compared with untreated controls (p<0.05). In vivo analysis of mouse corneal endothelium showed the following: endothelial cell density of lithium treated Q455K was higher than for untreated Q455K (p<0.01). transmission electron microscopy of lithium treated Q455K showed normal endothelium with enlarged autophagosomes, but untreated Q455K showed dilated ER and guttae. Compared with untreated Q455K endothelium, lithium treated Q455K showed significant upregulation of P62, Tmem74, Tm9sf1 and Tmem166 by RT-PCR and of Atg5-12 conjugate by western blotting indicating that lithium treatment increased autophagy. Although RT-PCR unexpectedly showed increased levels of lithium response genes, caspase 12, Gsk3, Arr2 and Impa1, western blotting showed the expected downregulation of Arr2 and Impa1 proteins in response to lithium treatment. Conclusions Lithium increases cultured CEC survival against ER and oxidative stress. Increased autophagy in lithium treated endothelium in a mouse model of FECD suggests autophagy may contribute to increased endothelial cell survival.
Serial induction of mutations by ethylnitrosourea in PC12 cells: a new model for a phenotypical characterization of the neurotoxic response to 6-hydroxydopamine
JOURNAL OF NEUROSCIENCE METHODS
Authors: Schlegel, J; Neff, F; Piontek, G
Abstract
Here we show that the serial generation of allelic mutations by treatment with the mutagen ethylnitrosourea (ENU) in PC 12 cells provides a new model for the phenotypical dissection of biological properties. We tested this approach in the neurotoxic 6-OHDA model of Parkinson's disease in PC12 cells which has been widely used as an in vitro model for the investigation of the molecular pathogenesis of neuronal cell death and for novel treatment approaches. ENU treatment at doses of 0.2 and 0.3 mg/ml for I h resulted in 35 and 25% surviving PC12 cells, respectively, which showed mutation frequencies of approximately 10 mutations per genome. Clones derived from single ENU treated PC 12 cells showed marked differences in their resistance against 6-OHDA. The phenotypical analysis of resistant and sensitive clones showed a differential transcriptional regulation of multiple genes. The applicability of this approach could be demonstrated by the identification of the rat TM9SF1 gene coding for a transmembrane protein of the nonaspanin superfamily as a regulated gene in PC 12 clones resistant against 6-OHDA. Our data demonstrate the suitability of this model for the investigation of the molecular pathogenesis of neurodegeneration and for high-throughput analysis, e.g. for drug discovery. (C) 2004 Elsevier B.V. All rights reserved.