Outer Hair Cell Lateral Wall Structure Constrains the Mobility of Plasma Membrane Proteins.
Nature's fastest motors are the cochlear outer hair cells (OHCs). These sensory cells use a membrane protein, Slc26a5 (prestin), to generate mechanical force at high frequencies, which is essential for explaining the exquisite hearing sensitivity of mammalian ears. Previous studies suggest that Slc26a5 continuously diffuses within the membrane, but how can a freely moving motor protein effectively convey forces critical for hearing? To provide direct evidence in OHCs for freely moving Slc26a5 molecules, we created a knockin mouse where Slc26a5 is fused with YFP. These mice and four other strains expressing fluorescently labeled membrane proteins were used to examine their lateral diffusion in the OHC lateral wall. All five proteins showed minimal diffusion, but did move after pharmacological disruption of membrane-associated structures with a cholesterol-depleting agent and salicylate. Thus, our results demonstrate that OHC lateral wall structure constrains the mobility of plasma membrane proteins and that the integrity of such membrane-associated structures are critical for Slc26a5's active and structural roles. The structural constraint of membrane proteins may exemplify convergent evolution of cellular motors across species. Our findings also suggest a possible mechanism for disorders of cholesterol metabolism with hearing loss such as Niemann-Pick Type C diseases.
Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, United States of America.
Tetsuji
T
Yamashita
Department of Clinical and Experimental Medicine, Neuroscience, Linköping University, Linköping, Sweden; Karolinska Institutet, Center for Hearing and Communication Research, Department of Clinical Science, Intervention, and Technology, M1, Karolinska University Hospital, Stockholm, Sweden.
Pierre
P
Hakizimana
Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.
Siva
S
Wu
Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.
Ahmed
A
Hassan
The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden.
Stefan
S
Jacob
Cell and Tissue Imaging Facility, St Jude Children's Research Hospital, Memphis, Tennessee, United States of America.
Jamshid
J
Temirov
Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, United States of America.
Jie
J
Fang
Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, United States of America; School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, United Kingdom.
Marcia
M
Mellado-Lagarde
Cell and Tissue Imaging Facility, St Jude Children's Research Hospital, Memphis, Tennessee, United States of America.
Richard
R
Gursky
Cell and Tissue Imaging Facility, St Jude Children's Research Hospital, Memphis, Tennessee, United States of America.
Linda
L
Horner
The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden.
Barbara
B
Leibiger
Karolinska Institutet, Center for Hearing and Communication Research, Department of Clinical Science, Intervention, and Technology, M1, Karolinska University Hospital, Stockholm, Sweden.
Sara
S
Leijon
Cell and Tissue Imaging Facility, St Jude Children's Research Hospital, Memphis, Tennessee, United States of America.
Victoria E
VE
Centonze
The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden.
Per-Olof
PO
Berggren
Cell and Tissue Imaging Facility, St Jude Children's Research Hospital, Memphis, Tennessee, United States of America.
Sharon
S
Frase
Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.
Manfred
M
Auer
Bobby R. Alford Department of Otolaryngology, Head & Neck Surgery, and Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America.
William E
WE
Brownell
Department of Clinical and Experimental Medicine, Neuroscience, Linköping University, Linköping, Sweden; Karolinska Institutet, Center for Hearing and Communication Research, Department of Clinical Science, Intervention, and Technology, M1, Karolinska University Hospital, Stockholm, Sweden.
Anders
A
Fridberger
Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, United States of America.
Jian
J
Zuo
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D018072:Hair Cells, Auditory, Outer / Q000378:metabolism*; D008164:Luminescent Proteins / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D020409:Molecular Motor Proteins / Q000378:metabolism*; D012243:Rhodopsin / Q000378:metabolism; D020156:Salicylic Acid / Q000494:pharmacology; D047392:beta-Cyclodextrins / Q000494:pharmacology
D001426:Bacterial Proteins; D008164:Luminescent Proteins; D020409:Molecular Motor Proteins; C498720:Pres protein, mouse; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; C054562:yellow fluorescent protein, Bacteria; D012243:Rhodopsin; D020156:Salicylic Acid