ELife Assessment: CaBP1 and 2 Enable Sustained CaV1.3 Calcium Currents and Synaptic Transmission in Inner Hair Cells

The study investigates the role of calcium-binding proteins, CaBP1 and 2, in the function of inner hair cells (IHCs), which are crucial for hearing. The absence of CaBP1 and 2 in IHCs significantly impairs synaptic exocytosis, a process crucial for sound encoding. This impairment is more severe with the absence of both proteins, suggesting that the roles of CaBP1 and 2 partially overlap. The loss of either CaBP1 or 2 can be largely compensated by the other, but the loss of CaBP2 alone still results in progressive hearing impairment. Overexpression of CaBP2 did not completely rescue the hearing phenotype of double knockout (DKO) animals, indicating that further experiments involving overexpression of CaBP1 are required. The study concludes that CaBPs are crucial in preventing extensive inactivation of CaV1.3 channels to support sufficient synaptic exocytosis for proper sound encoding.