Hearing is an essential sensory system relying on mechanotransduction that converts mechanical stimuli (sound signals) into electrical signals, which will then be transmitted to the central nervous system for further interpretation. Despite its importance in mammalian auditory system, little have the molecular composition and biochemical interactions involved in the mechanotransduction been thoroughly unveiled. Transmembrane channel-like protein 1 (TMC1) has been postulated as the pore-forming subunit of the auditory mechanoelectrical transducer (MET) channel owing to its predicted structure and physiological importance. TMC1 is known to interact with protocadherin-15 (PCDH15), one of the potential elements of gating spring that controls the open and close of the MET channel. Decipherin...[ Read more ]

Hearing is an essential sensory system relying on mechanotransduction that converts mechanical stimuli (sound signals) into electrical signals, which will then be transmitted to the central nervous system for further interpretation. Despite its importance in mammalian auditory system, little have the molecular composition and biochemical interactions involved in the mechanotransduction been thoroughly unveiled. Transmembrane channel-like protein 1 (TMC1) has been postulated as the pore-forming subunit of the auditory mechanoelectrical transducer (MET) channel owing to its predicted structure and physiological importance. TMC1 is known to interact with protocadherin-15 (PCDH15), one of the potential elements of gating spring that controls the open and close of the MET channel. Deciphering their interaction and roles in the system will help uncover the mystery of the mechanotransduction mechanism. Nevertheless, difficulties have continually been encountered because TMC1 cannot be expressed on the plasma membrane in heterologous systems, hampering the investigation and verification of its channel functions in a system, in which MET channel is naturally absent. Therefore, there has been an urgency in enabling the surface detection of TMC1 to facilitate the study of its functions and significance. In this study, apart from focusing on the physiological implications of the TMC1-PCDH15 interaction, several approaches are explored to enhance the TMC1 surface expression in the heterologous systems. The results suggest that TMC1 and PCDH15 interact in an unexpectedly robust manner that the open and close of the MET channel would have little impact on their binding. Additionally, the detection of the surface expressed TMC1 with the possible ER retention region removed is shown to be ameliorated with the deployment of a modified surface labelling immunocytochemistry. Collectively, this project provides insight into how TMC1 and PCDH15 may contribute to the hearing process, and the possibilities in enhancing plasma membrane proteins detection for TMC1 and other membrane proteins.