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 konckout 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）. 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. Key words: Myosin-light-chain Kinase ;  Mice, knockout;  Hair cells, inner;  Evokedpotentials, auditory, brain stem