Transcription Co-Factor LBH Is Necessary for Maintenance of Stereocilia Bundles and Survival of Cochlear Hair Cells

AbstractHearing loss affects ~10% of adults worldwide and is irreversible. Most sensorineural hearing loss is caused by progressive loss of mechanosensitive hair cells (HCs) in the cochlea of the inner ear. The molecular mechanisms underlying HC maintenance and loss are largely unknown. Our previous cell-specific transcriptome analysis showed that Limb-Bud-and-Heart (LBH), a transcription co-factor implicated in development, is abundantly expressed in outer hair cells (OHCs). We used Lbh-null mice to identify its role. Surprisingly, Lbh deletion did not affect differentiation and early development of HCs, as nascent HCs in Lbh knockout mice had normal looking stereocilia bundles. Whole-cell recording showed that the stereocilia bundle was mechanosensitive and OHCs exhibited the characteristic electromotility. However, Lbh-null mice displayed progressive hearing loss, with stereocilia bundle degeneration and OHC loss as early as postnatal day 12. Cell-specific RNA-seq and bioinformatic analyses identified Spp1, Six2, Gps2, Ercc6, Snx6 as well as Plscr1, Rarb, Per2, Gmnn and Map3k5 among the top five transcription factors up- or down-regulated in Lbh-null OHCs. Furthermore, this analysis showed significant gene enrichment of biological processes related to transcriptional regulation, cell cycle, DNA damage/repair and autophagy. In addition, Wnt and Notch pathway-related genes were found to be dysregulated in Lbh-deficient OHCs. We speculate that LBH may promote maintenance of HCs and stereocilia bundles by regulating Notch and Wnt signaling activity. Our study implicates, for the first time, loss of LBH function in progressive hearing loss, and demonstrates a critical requirement of LBH in promoting HC survival.

Download Full-text

Transcription co-factor LBH is necessary for the survival of cochlear hair cells

Journal of Cell Science ◽

10.1242/jcs.254458 ◽

2021 ◽

Vol 134 (7) ◽

Author(s):

Huizhan Liu ◽

Kimberlee P. Giffen ◽

M'Hamed Grati ◽

Seth W. Morrill ◽

Yi Li ◽

...

Keyword(s):

Hearing Loss ◽

Hair Cells ◽

Molecular Mechanisms ◽

Notch Pathway ◽

Outer Hair Cells ◽

Progressive Hearing Loss ◽

Cochlear Hair Cells ◽

Adult Mice ◽

Significant Gene ◽

Critical Requirement

ABSTRACT Hearing loss affects ∼10% of adults worldwide. Most sensorineural hearing loss is caused by the progressive loss of mechanosensitive hair cells (HCs) in the cochlea. The molecular mechanisms underlying HC maintenance and loss remain poorly understood. LBH, a transcription co-factor implicated in development, is abundantly expressed in outer hair cells (OHCs). We used Lbh-null mice to identify its role in HCs. Surprisingly, Lbh deletion did not affect differentiation and the early development of HCs, as nascent HCs in Lbh knockout mice had normal looking stereocilia. The stereocilia bundle was mechanosensitive and OHCs exhibited the characteristic electromotility. However, Lbh-null mice displayed progressive hearing loss, with stereocilia bundle degeneration and OHC loss as early as postnatal day 12. RNA-seq analysis showed significant gene enrichment of biological processes related to transcriptional regulation, cell cycle, DNA damage/repair and autophagy in Lbh-null OHCs. In addition, Wnt and Notch pathway-related genes were found to be dysregulated in Lbh-deficient OHCs. Our study implicates, for the first time, loss of LBH function in progressive hearing loss, and demonstrates a critical requirement of LBH in promoting HC survival in adult mice.

Download Full-text

Disruption of Hars2 in Cochlear Hair Cells Causes Progressive Mitochondrial Dysfunction and Hearing Loss in Mice

Frontiers in Cellular Neuroscience ◽

10.3389/fncel.2021.804345 ◽

2021 ◽

Vol 15 ◽

Author(s):

Pengcheng Xu ◽

Longhao Wang ◽

Hu Peng ◽

Huihui Liu ◽

Hongchao Liu ◽

...

Keyword(s):

Hearing Loss ◽

Hair Cell ◽

Mitochondrial Dysfunction ◽

Hair Cells ◽

Cell Loss ◽

Outer Hair Cells ◽

Hair Cell Loss ◽

Progressive Hearing Loss ◽

Cochlear Hair Cells ◽

Inner Hair Cells

Mutations in a number of genes encoding mitochondrial aminoacyl-tRNA synthetases lead to non-syndromic and/or syndromic sensorineural hearing loss in humans, while their cellular and physiological pathology in cochlea has rarely been investigated in vivo. In this study, we showed that histidyl-tRNA synthetase HARS2, whose deficiency is associated with Perrault syndrome 2 (PRLTS2), is robustly expressed in postnatal mouse cochlea including the outer and inner hair cells. Targeted knockout of Hars2 in mouse hair cells resulted in delayed onset (P30), rapidly progressive hearing loss similar to the PRLTS2 hearing phenotype. Significant hair cell loss was observed starting from P45 following elevated reactive oxygen species (ROS) level and activated mitochondrial apoptotic pathway. Despite of normal ribbon synapse formation, whole-cell patch clamp of the inner hair cells revealed reduced calcium influx and compromised sustained synaptic exocytosis prior to the hair cell loss at P30, consistent with the decreased supra-threshold wave I amplitudes of the auditory brainstem response. Starting from P14, increasing proportion of morphologically abnormal mitochondria was observed by transmission electron microscope, exhibiting swelling, deformation, loss of cristae and emergence of large intrinsic vacuoles that are associated with mitochondrial dysfunction. Though the mitochondrial abnormalities are more prominent in inner hair cells, it is the outer hair cells suffering more severe cell loss. Taken together, our results suggest that conditional knockout of Hars2 in mouse cochlear hair cells leads to accumulating mitochondrial dysfunction and ROS stress, triggers progressive hearing loss highlighted by hair cell synaptopathy and apoptosis, and is differentially perceived by inner and outer hair cells.

Download Full-text

Deletion of Tricellulin Causes Progressive Hearing Loss Associated with Degeneration of Cochlear Hair Cells

Scientific Reports ◽

10.1038/srep18402 ◽

2015 ◽

Vol 5 (1) ◽

Cited By ~ 34

Author(s):

Toru Kamitani ◽

Hirofumi Sakaguchi ◽

Atsushi Tamura ◽

Takenori Miyashita ◽

Yuji Yamazaki ◽

...

Keyword(s):

Hearing Loss ◽

Hair Cells ◽

Progressive Hearing Loss ◽

Cochlear Hair Cells

Download Full-text

Hearing Loss in Neurological Disorders

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.716300 ◽

2021 ◽

Vol 9 ◽

Author(s):

Siyu Li ◽

Cheng Cheng ◽

Ling Lu ◽

Xiaofeng Ma ◽

Xiaoli Zhang ◽

...

Keyword(s):

Hearing Loss ◽

Hair Cells ◽

Neurological Disorders ◽

Molecular Mechanisms ◽

Relevant Literature ◽

Autism Spectrum ◽

Supporting Cells ◽

Cochlear Hair Cells ◽

Wide Range ◽

Histological Characteristics

Sensorineural hearing loss (SNHL) affects approximately 466 million people worldwide, which is projected to reach 900 million by 2050. Its histological characteristics are lesions in cochlear hair cells, supporting cells, and auditory nerve endings. Neurological disorders cover a wide range of diseases affecting the nervous system, including Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), autism spectrum disorder (ASD), etc. Many studies have revealed that neurological disorders manifest with hearing loss, in addition to typical nervous symptoms. The prevalence, manifestations, and neuropathological mechanisms underlying vary among different diseases. In this review, we discuss the relevant literature, from clinical trials to research mice models, to provide an overview of auditory dysfunctions in the most common neurological disorders, particularly those associated with hearing loss, and to explain their underlying pathological and molecular mechanisms.

Download Full-text

Umbilical Cord Mesenchymal Stromal Cell-Derived Exosomes Rescue the Loss of Outer Hair Cells and Repair Cochlear Damage in Cisplatin-Injected Mice

International Journal of Molecular Sciences ◽

10.3390/ijms22136664 ◽

2021 ◽

Vol 22 (13) ◽

pp. 6664

Author(s):

Stella Chin-Shaw Tsai ◽

Kuender D. Yang ◽

Kuang-Hsi Chang ◽

Frank Cheau-Feng Lin ◽

Ruey-Hwang Chou ◽

...

Keyword(s):

Hearing Loss ◽

Umbilical Cord ◽

Hair Cells ◽

Round Window ◽

Outer Hair Cells ◽

Protective Effects ◽

Cochlear Hair Cells ◽

Potential Applications ◽

Round Window Niche

Umbilical cord-derived mesenchymal stromal cells (UCMSCs) have potential applications in regenerative medicine. UCMSCs have been demonstrated to repair tissue damage in many inflammatory and degenerative diseases. We have previously shown that UCMSC exosomes reduce nerve injury-induced pain in rats. In this study, we characterized UCMSC exosomes using RNA sequencing and proteomic analyses and investigated their protective effects on cisplatin-induced hearing loss in mice. Two independent experiments were designed to investigate the protective effects on cisplatin-induced hearing loss in mice: (i) chronic intraperitoneal cisplatin administration (4 mg/kg) once per day for 5 consecutive days and intraperitoneal UCMSC exosome (1.2 μg/μL) injection at the same time point; and (ii) UCMSC exosome (1.2 μg/μL) injection through a round window niche 3 days after chronic cisplatin administration. Our data suggest that UCMSC exosomes exert protective effects in vivo. The post-traumatic administration of UCMSC exosomes significantly improved hearing loss and rescued the loss of cochlear hair cells in mice receiving chronic cisplatin injection. Neuropathological gene panel analyses further revealed the UCMSC exosomes treatment led to beneficial changes in the expression levels of many genes in the cochlear tissues of cisplatin-injected mice. In conclusion, UCMSC exosomes exerted protective effects in treating ototoxicity-induced hearing loss by promoting tissue remodeling and repair.

Download Full-text

Elmod3 knockout leads to progressive hearing loss and abnormalities in cochlear hair cell stereocilia

Human Molecular Genetics ◽

10.1093/hmg/ddz240 ◽

2019 ◽

Vol 28 (24) ◽

pp. 4103-4112 ◽

Cited By ~ 2

Author(s):

Wu Li ◽

Yong Feng ◽

Anhai Chen ◽

Taoxi Li ◽

Sida Huang ◽

...

Keyword(s):

Hearing Loss ◽

Actin Cytoskeleton ◽

Hearing Impairment ◽

Hair Cells ◽

Organ Of Corti ◽

Vestibular Function ◽

Outer Hair Cells ◽

Auditory Function ◽

Cochlear Hair Cells

Abstract ELMOD3, an ARL2 GTPase-activating protein, is implicated in causing hearing impairment in humans. However, the specific role of ELMOD3 in auditory function is still far from being elucidated. In the present study, we used the CRISPR/Cas9 technology to establish an Elmod3 knockout mice line in the C57BL/6 background (hereinafter referred to as Elmod3−/− mice) and investigated the role of Elmod3 in the cochlea and auditory function. Elmod3−/− mice started to exhibit hearing loss from 2 months of age, and the deafness progressed with aging, while the vestibular function of Elmod3−/− mice was normal. We also observed that Elmod3−/− mice showed thinning and receding hair cells in the organ of Corti and much lower expression of F-actin cytoskeleton in the cochlea compared with wild-type mice. The deafness associated with the mutation may be caused by cochlear hair cells dysfunction, which manifests with shortening and fusion of inner hair cells stereocilia and progressive degeneration of outer hair cells stereocilia. Our finding associates Elmod3 deficiencies with stereocilia dysmorphologies and reveals that they might play roles in the actin cytoskeleton dynamics in cochlear hair cells, and thus relate to hearing impairment.

Download Full-text

The integrity of cochlear hair cells is established and maintained through the localization of Dia1 at apical junctional complexes and stereocilia

Cell Death and Disease ◽

10.1038/s41419-020-02743-z ◽

2020 ◽

Vol 11 (7) ◽

Author(s):

Yuzuru Ninoyu ◽

Hirofumi Sakaguchi ◽

Chen Lin ◽

Toshiaki Suzuki ◽

Shigeru Hirano ◽

...

Keyword(s):

Hearing Loss ◽

Hair Cells ◽

Noise Exposure ◽

Spiral Ganglion ◽

Cell Junctions ◽

Ultrastructural Changes ◽

Apical Surface ◽

Progressive Hearing Loss ◽

Cochlear Hair Cells ◽

Junctional Complexes

AbstractDia1, which belongs to the diaphanous-related formin family, influences a variety of cellular processes through straight actin elongation activity. Recently, novel DIA1 mutants such as p.R1213X (p.R1204X) and p.A265S, have been reported to cause an autosomal dominant sensorineural hearing loss (DFNA1). Additionally, active DIA1 mutants induce progressive hearing loss in a gain-of-function manner. However, the subcellular localization and pathological function of DIA1(R1213X/R1204X) remains unknown. In the present study, we demonstrated the localization of endogenous Dia1 and the constitutively active DIA1 mutant in the cochlea, using transgenic mice expressing FLAG-tagged DIA1(R1204X) (DIA1-TG). Endogenous Dia1 and the DIA1 mutant were regionally expressed at the organ of Corti and the spiral ganglion from early life; alongside cochlear maturation, they became localized at the apical junctional complexes (AJCs) between hair cells (HCs) and supporting cells (SCs). To investigate HC vulnerability in the DIA1-TG mice, we exposed 4-week-old mice to moderate noise, which induced temporary threshold shifts with cochlear synaptopathy and ultrastructural changes in stereocilia 4 weeks post noise exposure. Furthermore, we established a knock-in (KI) mouse line expressing AcGFP-tagged DIA1(R1213X) (DIA1-KI) and confirmed mutant localization at AJCs and the tips of stereocilia in HCs. In MDCKAcGFP-DIA1(R1213X) cells with stable expression of AcGFP-DIA1(R1213X), AcGFP-DIA1(R1213X) revealed marked localization at microvilli on the apical surface of cells and decreased localization at cell-cell junctions. The DIA1-TG mice demonstrated hazy and ruffled circumferential actin belts at AJCs and abnormal stereocilia accompanied with HC loss at 5 months of age. In conclusion, Dia1 plays a pivotal role in the development and maintenance of AJCs and stereocilia, ensuring cochlear and HC integrity. Subclinical/latent vulnerability of HCs may be the cause of progressive hearing loss in DFNA1 patients, thus suggesting new therapeutic targets for preventing HC degeneration and progressive hearing loss associated with DFNA1.

Download Full-text

Outcomes of Peptide Vaccine GV1001 Treatment in a Murine Model of Acute Noise-Induced Hearing Loss

Antioxidants ◽

10.3390/antiox9020112 ◽

2020 ◽

Vol 9 (2) ◽

pp. 112

Author(s):

Sang-Yeon Lee ◽

Jae Joon Han ◽

Sang-Youp Lee ◽

Gaon Jung ◽

Hyun Jin Min ◽

...

Keyword(s):

Oxidative Stress ◽

Hearing Loss ◽

White Noise ◽

Hair Cells ◽

Murine Model ◽

Outer Hair Cells ◽

Saline Control ◽

Noise Induced Hearing Loss ◽

Cochlear Hair Cells ◽

Ribbon Synapses

Noise-induced hearing loss (NIHL) is primarily caused by damage to cochlear hair cells, associated with synaptopathy. The novel cell-penetrating peptide GV1001, an antitumor agent, also has antioxidant and anti-inflammatory effects, and is otoprotective in a murine model of kanamycin-induced ototoxicity. Here, we explored whether GV1001 attenuated NIHL, and the underlying mechanism at play. We established an NIHL model by exposing 4- to 6-week-old C57/BL6 mice to white noise at 120 dB SPL for 2 h, resulting in a significant permanent threshold shift (PTS). We then subcutaneously injected saline (control), GV1001, or dexamethasone immediately after cessation of PTS-noise exposure and evaluated the threshold shifts, structural damages to outer hair cells (OHCs), and ribbon synapses. We also verified whether GV1001 attenuates oxidative stress at the level of lipid peroxidation or protein nitration in OHCs 1 h after exposure to white noise at 120 dB SPL. GV1001-treated mice exhibited significantly less hearing threshold shifts over 2 weeks and preserved OHCs and ribbon synapses compared with controls. Similarly, dexamethasone-treated mice showed comparable protection against NIHL. Importantly, GV1001 markedly attenuated oxidative stress in OHCs. Our findings suggest that GV1001 may protect against NIHL by lowering oxidative stress and may serve as preventive or adjuvant treatment.

Download Full-text