Lens ER-stress response during cataract development in Mip-mutant mice
BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR BASIS OF DISEASE
Authors: Zhou, Yuefang; Bennett, Thomas M.; Shiels, Alan
Abstract
Major intrinsic protein (MIP) is a functional water-channel (AQPO) that also plays a key role in establishing lens fiber cell architecture. Genetic variants of MIP have been associated with inherited and age-related forms of cataract; however, the underlying pathogenic mechanisms are unclear. Here we have used lens transcriptome profiling by microarray-hybridization and OCR to identify pathogenic changes during cataract development in Mip-mutant (Lop/ +) mice. In postnatal Lop/ + lenses (P7) 99 genes were up-regulated and 75 were down-regulated (>2-fold, p = <0.05) when compared with wild-type. A pathway analysis of up-regulated genes in the Lop/ + lens (P7) was consistent with endoplasmic reticulum (ER)-stress and activation of the unfolded protein response (UPR). The most up-regulated UPR genes (>4-fold) in the Lop/ + lens included Chacl > Ddit3 > Atf3 > Trib3 > Xbpl and the most down-regulated genes (>5-fold) included two anti-oxidant genes, Hspb1 and Hmox1. Lop/ + lenses were further characterized by abundant TUNEL-positive nuclei within central degenerating fiber cells, glutathione depletion, free-radical overproduction, and calpain hyper-activation. These data suggest that Lop/+ lenses undergo proteotoxic ER -stress induced cell-death resulting from prolonged activation of the Eif2ak3/Perk-Atf4-Ddit3-Chac1 branch of the UPR coupled with severe oxidative-stress. (C) 2016 The Authors. Published by Elsevier B.V.
Short exposure to cadmium disrupts the olfactory system of zebrafish (Danio rerio)-Relating altered gene expression in the olfactory organ to behavioral deficits
AQUATIC TOXICOLOGY
Authors: Volz, Sina N.; Hausen, Jonas; Nachev, Milen; Ottermanns, Richard; Schiwy, Sabrina; Hollert, Henner
Abstract
Fish strongly rely on olfaction as a variety of essential behaviors such as foraging and predator avoidance are mediated by the olfactory system. Cadmium (Cd) is known to impair olfaction and accumulate in the olfactory epithelium (OE) and bulb (OB) of fishes. In the present study, the acute toxicity of Cd on olfaction in zebrafish (Danio rerio) was characterized on the molecular and behavioral level. To this end, quantitative real-time PCR was performed in order to analyze the expression of selected genes in both the OE and OB. Moreover, the response of zebrafish to an alarm cue was investigated. Following 24 h of exposure to Cd, the expression of genes associated with olfactory sensory neurons was reduced in the OE. Furthermore, the antioxidant genes peroxiredoxin 1 (prdx1) and heme oxygenase 1 (hmox1), as well as the metallothionein 2 gene (mt2) were upregulated in the OE, whereas hmox1 and the stress-inducible heat shock protein 70 gene (hsp70) were upregulated in the OB upon exposure to Cd. Following stimulation with a conspecific skin extract, zebrafish displayed a considerable disruption of the antipredator behavior with increasing Cd concentration. Taken together, Cd impaired olfaction in zebrafish, thereby disrupting the antipredator response, which is crucial for the survival of individuals. Cellular stress followed by disruption of olfactory sensory neurons may have contributed to the observed behavioral deficits.