biostudies-literatureHussain SNational Institute on Deafness and Other Communication Disorders (NIDCD) Intramural Research Program33660https://www.ebi.ac.uk/biostudies/studies/S-EPMC12480455biostudies-literatureUnknown15(1)The hair bundle of auditory and vestibular hair cells converts mechanical stimuli into electrical signals through mechanoelectrical transduction (MET). The MET apparatus is built around a tip link that connects neighboring stereocilia that are aligned in the direction of mechanosensitivity of the hair bundle. Upon stimulation, the MET channel complex responds to changes in tip-link tension and allows a cation influx into the cell. Ca²⁺ influx in stereocilia has been used as a signature of MET activity. Using genetically encoded Ca²⁺ sensors (GCaMP3, GCaMP6s) and high-performance fluorescence confocal microscopy, we detect spontaneous Ca²⁺ transients in individual stereocilia in developing and fully formed hair bundles. We demonstrate that this activity is aScientific reportsSpontaneous calcium transients in hair cell stereocilia.PMC12480455Z01-DC0000021ZIADC000085-01Sedlacek MKachar BHussain SBergles DEShin JBKindt KSZhang-Hooks WCui RfalseSpontaneous calcium transients in hair cell stereocilia.The hair bundle of auditory and vestibular hair cells converts mechanical stimuli into electrical signals through mechanoelectrical transduction (MET). The MET apparatus is built around a tip link that connects neighboring stereocilia that are aligned in the direction of mechanosensitivity of the hair bundle. Upon stimulation, the MET channel complex responds to changes in tip-link tension and allows a cation influx into the cell. Ca²⁺ influx in stereocilia has been used as a signature of MET activity. Using genetically encoded Ca²⁺ sensors (GCaMP3, GCaMP6s) and high-performance fluorescence confocal microscopy, we detect spontaneous Ca²⁺ transients in individual stereocilia in developing and fully formed hair bundles. We demonstrate that this activity is a2025-01-01T00:00:00Z2025 Sep2026-06-04T05:09:27.139Z2026-05-05T03:12:46.379ZS-EPMC124804554102288610.1038/s41598-025-17976-1