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. 2017 Dec 1;9(12):1711–1731. doi: 10.15252/emmm.201708087

Figure 1. CIB2 isoforms and hearing sensitivity in CIB2 −/− mice.

Figure 1

  • A
    Domain structure of the CIB2 protein, indicating the positions of the CIB2 mutations in USH1J (red) and DFNB48 (green) patients. The CIB2‐floxed mice, CIB2 fl/fl, were engineered by adding LoxP sites on either side of exon 4, which is common to all four known CIB2 transcripts.
  • B
    RT–PCR analysis confirming the loss of CIB2 exon 4‐containing transcripts in the inner ear, eye, brain, muscle, kidney and testis of CIB2 −/− mice. β‐Actin was used as an endogenous control.
  • C, D
    ABR thresholds (C) and DPOAE amplitudes (D) in CIB2 +/− (dark, n = 6) and CIB2 −/− (red, n = 9) P20‐P25 mice. ABR thresholds in CIB2 −/− mice exceeded 100 dB SPL (mean ± SD), indicating profound deafness. (D) DPOAE amplitudes were absent in CIB2 −/− P20 mice at 10 and 15 kHz (red) (Mann–Whitney, ***P = 0.002 for both 10 and 15 kHz).
  • E
    MET responses in OHCs from CIB2 +/− and CIB2 −/− P7 mice. The left panels show the mechanical stimulation protocol, with examples of MET currents for each genotype. In the right panels, the MET current values and mean amplitude‐displacement relationships (I(X)) (mean ± SD) in CIB2 +/− (black, n = 3 cells) and CIB2 −/− (red, n = 5) mice highlight the absence of a MET response in CIB2 −/− OHCs (Welch's unpaired t‐test, ****P = 0.0007).