Lhfpl5, lipoma HMGIC fusion partner-like 5, is a crucial transmembrane protein involved in the mechano-electrical transduction (MET) process in cochlear hair cells. It plays a vital role in our senses of hearing and balance by enabling the conversion of mechanical stimuli into electrical signals. Lhfpl5 is thought to form a multi-protein complex with other MET channel proteins such as PCDH15, TMIE, and TMC1 [2].

In Lhfpl5 -/- knockout mice, compared with Lhfpl5+/- heterozygotes, the working range of MET channel activation in outer hair cells increased, and the single-channel gating force decreased, indicating reduced sensitivity. The gating stiffness, a key factor in channel activation, was virtually abolished in Lhfpl5 -/-, suggesting LHFPL5 is a principal component of the gating spring that transmits tip-link tension to the MET channel [1]. Also, disruption of the interaction between LHFPL5 and TMC1, like in the Tmc1 p.D569N mutation, which reduced LHFPL5 immunolabeling in stereocilia, led to a doubling of the MET working range [1].

In conclusion, Lhfpl5 is essential for establishing the maximal force sensitivity of the MET channel in cochlear hair cells. Its role in directly coupling the tip link to the MET channel is demonstrated through gene knockout mouse models. Mutations in Lhfpl5 can cause non-syndromic autosomal recessive hearing loss, highlighting its significance in understanding the genetic basis of hearing disorders [1,3].

References:

1. Beurg, Maryline, Schwalbach, Evan Travis, Fettiplace, Robert. 2024. LHFPL5 is a key element in force transmission from the tip link to the hair cell mechanotransducer channel. In Proceedings of the National Academy of Sciences of the United States of America, 121, e2318270121. doi:10.1073/pnas.2318270121. https://pubmed.ncbi.nlm.nih.gov/38194445/

2. Soler, David C, Ballesteros, Angela, Sloan, Andrew E, McCormick, Thomas S, Stepanyan, Ruben. 2023. Multiple plasma membrane reporters discern LHFPL5 region that blocks trafficking to the plasma membrane. In Scientific reports, 13, 2528. doi:10.1038/s41598-023-28045-w. https://pubmed.ncbi.nlm.nih.gov/36781873/

3. Al-Amri, Ahmed H, Al Saegh, Abeer, Al-Mamari, Watfa, Clapcote, Steven J, Ali, Manir. 2018. LHFPL5 mutation: A rare cause of non-syndromic autosomal recessive hearing loss. In European journal of medical genetics, 62, 103592. doi:10.1016/j.ejmg.2018.11.026. https://pubmed.ncbi.nlm.nih.gov/30476627/