TY - JOUR
T1 - Ca2+ entry through mechanotransduction channels localizes BAIAP2L2 to stereocilia tips
AU - Halford, Julia
AU - Bateschell, Michael
AU - Barr-Gillespie, Peter G.
N1 - Funding Information:
Jennifer Goldsmith provided excellent mouse husbandry. Jonathan Bird kindly provided us with Myo15aΔN tissue and the egfp-Myo15a(tail) plasmid; the Gfp-Myo10(HMM) plasmid was a gift from Richard Cheney. The pan-MYO15A antibody was generously provided by Tom Friedman. We thank Andy Griffith for the Tmc1KO and Tmc2KO mouse lines and Uli Müller for the TmieKO mouse line. Confocal microscopy was performed at the OHSU Advanced Light Microscopy Core at The Jungers Center (supported by P30 NS061800). The study was supported by a grant to P.G.B-G (National Institutes of Health, R01DC002368).
Publisher Copyright:
© 2022 Halford et al.
PY - 2022/4/1
Y1 - 2022/4/1
N2 - Brain-specific angiogenesis inhibitor 1-associated protein 2-like protein 2 (BAIAP2L2), a membrane-binding protein required for the maintenance of mechanotransduction in hair cells, is selectively retained at the tips of transducing stereocilia. BAIAP2L2 trafficked to stereocilia tips in the absence of EPS8, but EPS8 increased the efficiency of localization. A tripartite complex of BAIAP2L2, EPS8, and MYO15A formed efficiently in vitro, and these three proteins robustly targeted to filopodia tips when coexpressed in cultured cells. Mice lacking functional transduction channels no longer concentrated BAIAP2L2 at row 2 stereocilia tips, a result that was phenocopied by blocking channels with tubocurarine in cochlear explants. Transduction channels permit Ca2+ entry into stereocilia, and we found that membrane localization of BAIAP2L2 was enhanced in the presence of Ca2+. Finally, reduction of intracellular Ca2+ in hair cells using BAPTA-AM led to a loss of BAIAP2L2 at stereocilia tips. Taken together, our results show that a MYO15A-EPS8 complex transports BAIAP2L2 to stereocilia tips, and Ca2+ entry through open channels at row 2 tips retains BAIAP2L2 there.
AB - Brain-specific angiogenesis inhibitor 1-associated protein 2-like protein 2 (BAIAP2L2), a membrane-binding protein required for the maintenance of mechanotransduction in hair cells, is selectively retained at the tips of transducing stereocilia. BAIAP2L2 trafficked to stereocilia tips in the absence of EPS8, but EPS8 increased the efficiency of localization. A tripartite complex of BAIAP2L2, EPS8, and MYO15A formed efficiently in vitro, and these three proteins robustly targeted to filopodia tips when coexpressed in cultured cells. Mice lacking functional transduction channels no longer concentrated BAIAP2L2 at row 2 stereocilia tips, a result that was phenocopied by blocking channels with tubocurarine in cochlear explants. Transduction channels permit Ca2+ entry into stereocilia, and we found that membrane localization of BAIAP2L2 was enhanced in the presence of Ca2+. Finally, reduction of intracellular Ca2+ in hair cells using BAPTA-AM led to a loss of BAIAP2L2 at stereocilia tips. Taken together, our results show that a MYO15A-EPS8 complex transports BAIAP2L2 to stereocilia tips, and Ca2+ entry through open channels at row 2 tips retains BAIAP2L2 there.
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U2 - 10.1091/mbc.E21-10-0491
DO - 10.1091/mbc.E21-10-0491
M3 - Article
C2 - 35044843
AN - SCOPUS:85128160155
SN - 1059-1524
VL - 33
JO - Molecular biology of the cell
JF - Molecular biology of the cell
IS - 4
M1 - br6
ER -