Myosin Light-Chain Kinase Is Necessary for Membrane Homeostasis in Cochlear Inner Hair Cells
Figure 2
Disruption of the Mylk gene in IHCs and ABR threshold analyses.
(A) Generation of knockout mice with deletion of Mylk in the IHCs (schematic). The 1.4-kb genomic DNA fragment contains Mylk exons 23–25 (Mylk accession number: NC_000082), which encode the adenosine triphosphate-binding site of the kinase. Mice containing the floxed allele were crossed with IHC-Cre mice to generate Mylkflox/+ (CTR) and Mylkflox/flox;IHC-Cre (MLCKIKO) mice. The locations of PCR primers a and b are indicated by arrows. (B) DNA isolated from CTR and MLCKIKO mice IHCs and OHCs was analyzed by PCR; the 1.4-kb and 308-bp products represent CTR and mutated MLCK, respectively. (C) Representative ABR waveforms measured in CTR and MLCKIKO knockout mice at 4–6 months in age measured in response to click stimuli of the indicated intensities. *ABR threshold. (D) Summary of the ABR thresholds for click and tone stimuli in 4- to 6-month-old control (filled circles) (n = 13) and MLCK-null mice (open circles) (n = 18). Averaged data (means ± S.E.) are shown for the click and tone stimuli. *Significant difference compared with control mice are shown. *, P<0.05; **, P<0.01.