[Study on conditional myosin light chain kinase gene knockout mice resulting in hearing loss].

Objective: To investigate the function of myosin light chain kinase (MLCK) in hearing in mouse by generating inner hair cell-specific Mlck knockout mice and analyze the effect on their hearing.

Methods: Cross Mlck floxed mice with IHC-Cre mice, the genotype and knockout efficiency were confirmed by PCR. We used auditory brain stem response (ABR) to evaluate mice hearing function at different frequencies.

Results: Mlck knockout mice were selected by mice tail DNA genotyping and confirmed the deletion of the target gene by isolated inner hair cell DNA genotyping. Mlck-deficient mice showed impaired hearing with a rise in ABR threshold response to click and three different pure tones (8 kHz, 16 kHz, 32 kHz), and the rise was over 20 dB at high-frequency(32 kHz). Further analyses of waveforms showed that wave-I amplitudes on 60 dB SPL, 50 dB SPL and 40 dBSPL in response to tone (16 kHz) were less than control group(P < 0.05) on average, but the ratio of wave I/II and I/III were not difference (P > 0.05).

Conclusions: Mlck is successfully deleted in inner hair cell-specific Mlck knockout mice. Mlck knockout mice display a significantly higher threshold in response to click and tones, especially in high-frequencies.