生物谷報(bào)道：內(nèi)耳的毛細(xì)胞之所以被這么稱呼，是因?yàn)橛忻粯拥臇|西（立纖毛）從它們的頂部表面伸出,。由聲音誘導(dǎo)的立纖毛運(yùn)動(dòng),，被認(rèn)為是通過將立纖毛彼此連接起來的“端部聯(lián)結(jié)”（tip links）與機(jī)電傳導(dǎo)通道耦合在一起的。現(xiàn)在,，Kazmierczak等人報(bào)告了哺乳動(dòng)物“端部聯(lián)結(jié)”的構(gòu)造,。它們是由鈣依賴型細(xì)胞黏附蛋白家族的兩個(gè)成員cadherin 和protocadherin 15之間的相互作用形成的。有趣的是,，這些cadherins的突變引起人失聰,，而且這樣一個(gè)突變破壞了兩個(gè)分子之間的相互作用。
原始出處:
Nature 449, 87-91 (6 September 2007) | doi:10.1038/nature06091; Received 17 April 2007; Accepted 10 July 2007
Cadherin 23 and protocadherin 15 interact to form tip-link filaments in sensory hair cells
Piotr Kazmierczak1,2,4, Hirofumi Sakaguchi3,4, Joshua Tokita3, Elizabeth M. Wilson-Kubalek1, Ronald A. Milligan1, Ulrich Müller1,2,4 & Bechara Kachar3,4
The Scripps Research, Institute Department of Cell Biology,
Institute for Childhood and Neglected Disease, La Jolla, California 92037, USA
Laboratory of Cellular Biology, National Institute on Deafness and other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
These authors contributed equally to this work.
Correspondence to: Ulrich Müller1,2,4Bechara Kachar3,4 Correspondence and requests for materials should be addressed to U.M. (Email: [email protected]) or B.K. (Email: [email protected]).
Hair cells of the inner ear are mechanosensors that transduce mechanical forces arising from sound waves and head movement into electrochemical signals to provide our sense of hearing and balance. Each hair cell contains at the apical surface a bundle of stereocilia. Mechanoelectrical transduction takes place close to the tips of stereocilia in proximity to extracellular tip-link filaments that connect the stereocilia and are thought to gate the mechanoelectrical transduction channel1, 2, 3. Recent reports on the composition4, 5, 6, 7, 8, properties and function9, 10, 11 of tip links are conflicting29. Here we demonstrate that two cadherins that are linked to inherited forms of deafness in humans12, 13, 14, 15 interact to form tip links. Immunohistochemical studies using rodent hair cells show that cadherin 23 (CDH23) and protocadherin 15 (PCDH15) localize to the upper and lower part of tip links, respectively. The amino termini of the two cadherins co-localize on tip-link filaments. Biochemical experiments show that CDH23 homodimers interact in trans with PCDH15 homodimers to form a filament with structural similarity to tip links. Ions that affect tip-link integrity and a mutation in PCDH15 that causes a recessive form of deafness16 disrupt interactions between CDH23 and PCDH15. Our studies define the molecular composition of tip links and provide a conceptual base for exploring the mechanisms of sensory impairment associated with mutations in CDH23 and PCDH15.
