Deletion of Limk1 and Limk2 in mice does not alter cochlear development or auditory function

Abstract

Inherited hearing loss is associated with gene mutations that result in sensory hair cell (HC) malfunction. HC structure is defined by the cytoskeleton, which is mainly composed of actin filaments and actin-binding partners. LIM motif-containing protein kinases (LIMKs) are the primary regulators of actin dynamics and consist of two members: LIMK1 and LIMK2. Actin arrangement is directly involved in the regulation of cytoskeletal structure and the maturation of synapses in the central nervous system, and LIMKs are involved in structural plasticity by controlling the activation of the actin depolymerization protein cofilin in the olfactory system and in the hippocampus. However, the expression pattern and the role of LIMKs in mouse cochlear development and synapse function also need to be further studied. We show here that the Limk genes are expressed in the mouse cochlea. We examined the morphology and the afferent synapse densities of HCs and measured the auditory function in Limk1 and Limk2 double knockout (DKO) mice. We found that the loss of Limk1 and Limk2 did not appear to affect the overall development of the cochlea, including the number of HCs and the structure of hair bundles. There were no significant differences in auditory thresholds between DKO mice and wild-type littermates. However, the expression of p-cofilin in the DKO mice was significantly decreased. Additionally, no significant differences were found in the number or distribution of ribbon synapses between the DKO and wild-type mice. In summary, our data suggest that the Limk genes play a different role in the development of the cochlea compared to their role in the central nervous system.

CCDC154 Mutant Caused Abnormal Remodeling of the Otic Capsule and Hearing Loss in Mice

“…Knockdown Arhgef6 in mice caused progressive hearing loss due to HC loss and stereocilia deficits ( Zhu et al, 2018 ). Fang et al (2019) reported that loss of Limk1 and Limk2 did not affect the overall development of the cochlea and the structure of hair bundles. CCDC154 is not necessary for the survival of hair cells or spiral ganglion cells.…”

Deletion of Clusterin Protects Cochlear Hair Cells against Hair Cell Aging and Ototoxicity

“…HCs in the inner ear cochlea function in transducing sound waves into electric signals [17][18][19][20][21], while supporting cells function in supporting the HCs and providing the potential pool for HC regeneration [22][23][24][25][26]. Damages from a variety of sources can impair HC function, including genetic factors, aging, ototoxic drugs, chronic cochlear infections, and noise exposure [19,[27][28][29][30][31]. In this study, we reported the protective effect of Clusterin deficiency against age-related hearing loss and drug-induced ototoxicity, which are both due to irreversible loss of sensory HCs [32][33][34][35][36] and degeneration of the spiral ganglion neurons (SGNs) [37][38][39][40][41][42].…”

Deletion of Kcnj16 in Mice Does Not Alter Auditory Function

“…Whole-mount immunohistochemistry was performed as previously described ( Fang et al, 2019 ). The cochleae were dissected from the temporal bones in cold PBS and were then fixed in 4% polyoxymethylene (Sigma,158127) for 1 h, followed by permeabilization with 0.1% Triton X-100 (Solarbio, T8200-500) for 1 h. After blocking (10% donkey serum, 0.5% Triton X-100, and 1% BSA in PBS at pH 7.2) for 1 h at room temperature, the sensory epithelia were incubated with the following primary antibodies overnight at 4°C: anti-Kir5.1 (Abnova, PBA-18407); anti-Myo7A (Proteus Bioscience, 25-6790; DSHB,138-1); anti-Sox2 (Santa Cruz Biotechnology, sc-17320); anti-CtBP2 (BD Biosciences, 612044); and anti-PSD95 (Millipore, MAB1596).…”