XBP1 mitigates aminoglycoside-induced endoplasmic reticulum stress and neuronal cell death

Abstract

Here we study links between aminoglycoside-induced mistranslation, protein misfolding and neuropathy. We demonstrate that aminoglycosides induce misreading in mammalian cells and assess endoplasmic reticulum (ER) stress and unfolded protein response (UPR) pathways. Genome-wide transcriptome and proteome analyses revealed upregulation of genes related to protein folding and degradation. Quantitative PCR confirmed induction of UPR markers including C/EBP homologous protein, glucose-regulated protein 94, binding immunoglobulin protein and X-box binding protein-1 (XBP1) mRNA splicing, which is crucial for UPR activation. We studied the effect of a compromised UPR on aminoglycoside ototoxicity in haploinsufficient XBP1 (XBP1+/−) mice. Intra-tympanic aminoglycoside treatment caused high-frequency hearing loss in XBP1+/− mice but not in wild-type littermates. Densities of spiral ganglion cells and synaptic ribbons were decreased in gentamicin-treated XBP1+/− mice, while sensory cells were preserved. Co-injection of the chemical chaperone tauroursodeoxycholic acid attenuated hearing loss. These results suggest that aminoglycoside-induced ER stress and cell death in spiral ganglion neurons is mitigated by XBP1, masking aminoglycoside neurotoxicity at the organismal level.

Endoplasmic Reticulum Stress in Hearing Loss

“…Interestingly, XBP1 could alleviate aminoglycoside-induced ER stress and hearing loss. Aminoglycoside-induced UPR was compromised and more severe hearing loss was observed in Xbp1 +/− mice compared with wild-type mice [41]. Moreover, treatment of the chemical chaperone tauroursodeoxycholic acid (TUDCA) attenuated aminoglycoside-induced hearing loss in Xbp1 +/− mice, further supporting the hypothesis that UPR could protect drug-induced hearing loss [41].…”

“…In cultured cells derived from mouse organ of Corti (HEI-OC1), APAP or NAPQI treatment alters eIF2α phosphorylation as well as CHOP expression independent of ATF4 activation, and results in cell death [40]. In contrast, aminoglycosides activate all three UPR pathways in cultured HEK293 cells [41]. Interestingly, XBP1 could alleviate aminoglycoside-induced ER stress and hearing loss.…”

“…Furthermore, perilymphatic perfusion of the ER-stress-activator tunicamycin results in profound hearing loss in rats [42]. In the cochlea, ER stress affects different cell types including hair cells (HCs), spiral ganglion cells (SGCs), and fibrocytes, depending on the chemicals used [39,41,42]. For example, tunicamycin induces ER stress in HCs and SGCs; in contrast, gentamicin induces ER stress in SGCs but not in HCs [41].…”

“…Animal and cell experiments have showed that ER stress is involved in hearing loss induced by ototoxic drugs such as aminoglycosides, 3-nitropropionic acid (3-NP), N-acetyl-para-aminophenol (APAP), and N-acetyl-p-benzoquinoneimine (NAPQI) [39][40][41]. Furthermore, perilymphatic perfusion of the ER-stress-activator tunicamycin results in profound hearing loss in rats [42].…”

Readthrough-Promoting Drugs Gentamicin and PTC124 Fail to Rescue Na v 1.5 Function of Human-Induced Pluripotent Stem Cell–Derived Cardiomyocytes Carrying Nonsense Mutations in the Sodium Channel Gene SCN5A

“…Immunofluorescence demonstrated the presence of GFP in gentamicin-and PTC124-treated cells transfected with H2B-GFP opal, whereas untreated cells did not demonstrate any signal, indicating the potency of these drugs in evoking readthrough ( Figure 5A). To demonstrate that gentamicin was actually present in the nucleus of hiPSC-CMs, genes known to be upregulated after gentamicin exposure 25 were examined by quantitative PCR. GRP94, CHOP, and BiP expressions were upregulated in gentamicin-treated hiPSC-CM R1638X and hiPSC-CM W156X compared with untreated cells from the same line ( Figure 5B).…”