In vivo overexpression of X-linked inhibitor of apoptosis protein protects against neomycin-induced hair cell loss in the apical turn of the cochlea during the ototoxic-sensitive period

Abstract

Aminoglycoside-induced cochlear ototoxicity causes hair cell (HC) loss and results in hearing impairment in patients. Previous studies have developed the concept of an ototoxicity-sensitive period during which the cochleae of young mice are more vulnerable to auditory trauma than adults. Here, we compared neomycin-induced ototoxicity at the following four developmental ages in mice: postnatal day (P)1–P7, P8–P14, P15–P21, and P60–P66. We found that when neomycin was administered between P8 and P14, the auditory brainstem response threshold increase was significantly higher at low frequencies and HC loss was significantly greater in the apical turn of the cochlea compared to neomycin administration during the other age ranges. Quantitative real-time PCR (qPCR) data revealed that the expression of apoptotic markers, including Casp3 and Casp9, was significantly higher when neomycin was injected from P8 to P14, while the expression of the X-linked inhibitor of apoptosis protein (XIAP) gene was significantly higher when neomycin was injected from P60 to P66. Because XIAP expression was low during the neomycin-sensitive period, we overexpressed XIAP in mice and found that it could protect against neomycin-induced hearing loss at low frequencies and HC loss in the apical turn of the cochlea. Altogether, our findings demonstrate a protective role for XIAP against neomycin-induced hearing loss and HC loss in the apical turn of the cochlea during the ototoxic-sensitive period, and suggest that apoptotic factors mediate the effect of neomycin during the ototoxic-sensitive period.

c-Myb knockdown increases the neomycin-induced damage to hair-cell-like HEI-OC1 cells in vitro

“…6a,c). Previous studies have reported that cleaved caspase-3 and TUNEL can be used as markers of apoptosis in aminoglycoside-induced HC death303233343536. To confirm our findings, we performed active caspase-3 and TUNEL staining to detect the apoptotic HEI-OC1 cells.…”

“…To determine whether the c-Myb expression in cochlear HCs was affected by neomycin treatment, C57BL/6 mice were given daily subcutaneous injections of neomycin (200 mg/kg) from P7 to P14, which is the ototoxic-sensitive period in the cochlea32. Mice in the control group were given sterile saline.…”

“…Mice in the control group were given sterile saline. At P17, the cochlear sensory epithelium was dissected out, and as reported before, the HC loss after neomycin injection forms a gradient from the apex to the base with the basal turns having greater HC loss than the apical turns32. We chose the middle turn as the representative image (Fig.…”

Citicoline Protects Auditory Hair Cells Against Neomycin-Induced Damage

“…Ototoxic drugs cause hearing loss by inducing HC apoptosis, primarily by altering the MMP of the mitochondria ( Huang et al, 2000 ; Wu et al, 2002 ; Sun et al, 2015 ; Guan et al, 2016 ; He et al, 2016 ; Yu et al, 2017 ). Mitochondria play an important role in cell metabolism, and aminoglycoside-induced apoptosis is closely related to mitochondrial dysfunction, which leads to decreased MMP and increased ROS ( Joza et al, 2001 ; Chipuk et al, 2004 ; Coffin et al, 2013 ; Sun et al, 2014 , 2015 ; Mei et al, 2015 ). The accumulation of ROS in the mitochondria is an important trigger of apoptosis, and it has been reported that ROS play an important role in noise-induced and ototoxic drug-induced HC damage and hearing loss ( Sun et al, 2014 , 2015 ; Chen et al, 2015 ).…”

“…Therefore, it is important to investigate the molecular mechanism behind aminoglycoside-induced auditory sensory cell damage and to seek effective drugs for preventing and treating aminoglycoside-induced deafness. Several studies have suggested that aminoglycosides induce intrinsic apoptosis of HCs through oxidative stress ( Mangiardi et al, 2004 ; Coffin et al, 2013 ; Sun et al, 2014 , 2015 ; Liu et al, 2016 ), while others have reported that the accumulation of reactive oxygen species (ROS) plays an important role in the death of HCs ( Clerici et al, 1996 ; Choung et al, 2009 ). ROS can be cleared by physiological cellular processes; however, they are harmful when their concentration exceeds the cell’s capacity to remove them ( He et al, 2020 ).…”