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Park C, Thein P, Kalinec G, Kalinec F. HEI-OC1 cells as a model for investigating prestin function. Hear Res 2016; 335:9-17. [PMID: 26854618 DOI: 10.1016/j.heares.2016.02.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 12/05/2015] [Accepted: 02/03/2016] [Indexed: 10/22/2022]
Abstract
The House Ear Institute-Organ of Corti 1 (HEI-OC1) is a mouse auditory cell line that endogenously express, among other several markers of cochlear hair cells, the motor protein prestin (SLC26A5). Since its discovery fifteen years ago, and because of the difficulties associated with working with outer hair cells, prestin studies have been performed mostly by expressing it exogenously in non-specific systems such as HEK293 and TSA201, embryonic kidney cells from human origin, or Chinese Hamster Ovary (CHO) cells. Here, we report flow cytometry and confocal laser scanning microscopy studies on the pattern of prestin expression, as well as nonlinear capacitance (NLC) and whole cell-patch clamping studies on prestin motor function, in HEI-OC1 cells cultured at permissive and non-permissive conditions. Our results indicate that both total prestin expression and plasma membrane localization increase in a time-dependent manner when HEI-OC1 cells differentiate under non-permissive culture conditions. In addition, we demonstrate that HEI-OC1 cells have a robust NLC associated to prestin motor function, which decreases when the density of prestin molecules present at the plasma membrane increases. Altogether, our results show that the response of endogenously expressed prestin in HEI-OC1 cells is different from the response of prestin expressed exogenously in non-auditory cells, and suggest that the HEI-OC1 cell line may be an important additional tool for investigating prestin function.
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Affiliation(s)
- Channy Park
- Laboratory of Auditory Cell Biology, Department of Head & Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Pru Thein
- Laboratory of Auditory Cell Biology, Department of Head & Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Gilda Kalinec
- Laboratory of Auditory Cell Biology, Department of Head & Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Federico Kalinec
- Laboratory of Auditory Cell Biology, Department of Head & Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
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Yamashita T, Hakizimana P, Wu S, Hassan A, Jacob S, Temirov J, Fang J, Mellado-Lagarde M, Gursky R, Horner L, Leibiger B, Leijon S, Centonze VE, Berggren PO, Frase S, Auer M, Brownell WE, Fridberger A, Zuo J. Outer Hair Cell Lateral Wall Structure Constrains the Mobility of Plasma Membrane Proteins. PLoS Genet 2015; 11:e1005500. [PMID: 26352669 PMCID: PMC4564264 DOI: 10.1371/journal.pgen.1005500] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 08/14/2015] [Indexed: 12/02/2022] Open
Abstract
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. Nature’s fastest motor is the cochlear outer hair cell (OHC) in the mammalian inner ear. These cells can contract and elongate thousands of times per second. Slc26a5 (prestin) is the essential protein in the fast motor and resides in the plasma membrane of OHC lateral wall. Slc26a5 undergoes voltage-dependent conformational changes associated with the rapid changes in cell length to increase mammalian hearing sensitivity. However, it remains unclear how Slc26a5 transfers the force created to the entire cell. In this study, we show the importance of association between Slc26a5 and specialized membrane structures of the OHC lateral wall. Mobility of Slc26a5 was normally constrained in membrane-associated structures and disruption of these structures by a cholesterol depleting reagent and salicylate liberated Slc26a5 and four other heterologously expressed membrane proteins. These observations provide evidence that OHC lateral wall structure constrains the mobility of plasma membrane proteins and such membrane-associated structures are critical for Slc26a5’s functional roles. Our findings also shed light on other cellular motors across species and suggest a mechanism for cholesterol metabolic disorders in humans.
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Affiliation(s)
- Tetsuji Yamashita
- Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Pierre Hakizimana
- 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
| | - Siva Wu
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Ahmed Hassan
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Stefan Jacob
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Jamshid Temirov
- Cell and Tissue Imaging Facility, St Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Jie Fang
- Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Marcia Mellado-Lagarde
- 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
| | - Richard Gursky
- Cell and Tissue Imaging Facility, St Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Linda Horner
- Cell and Tissue Imaging Facility, St Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Barbara Leibiger
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Sara Leijon
- Karolinska Institutet, Center for Hearing and Communication Research, Department of Clinical Science, Intervention, and Technology, M1, Karolinska University Hospital, Stockholm, Sweden
| | - Victoria E. Centonze
- Cell and Tissue Imaging Facility, St Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Per-Olof Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Sharon Frase
- Cell and Tissue Imaging Facility, St Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Manfred Auer
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - William E. Brownell
- Bobby R. Alford Department of Otolaryngology, Head & Neck Surgery, and Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
| | - Anders Fridberger
- 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
| | - Jian Zuo
- Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
- * E-mail:
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Park C, Kalinec F. PKCα-Mediated Signals Regulate the Motile Responses of Cochlear Outer Hair Cells. Biophys J 2015; 108:2171-80. [PMID: 25954875 PMCID: PMC4423042 DOI: 10.1016/j.bpj.2015.03.044] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Revised: 03/09/2015] [Accepted: 03/23/2015] [Indexed: 12/29/2022] Open
Abstract
There is strong evidence that changes in the actin/spectrin-based cortical cytoskeleton of outer hair cells (OHCs) regulate their motile responses as well as cochlear amplification, the process that optimizes the sensitivity and frequency selectivity of the mammalian inner ear. Since a RhoA/protein kinase C (PKC)-mediated pathway is known to inhibit the actin-spectrin interaction in other cell models, we decided to investigate whether this signaling cascade could also participate in the regulation of OHC motility. We used high-speed video microscopy and confocal microscopy to explore the effects of pharmacological activation of PKCα, PKCβI, PKCβII, PKCδ, PKCε, and PKCζ with lysophosphatidic acid (LPA) and their inhibition with bisindolylmaleimide I, as well as inhibition of RhoA and Rho-associated protein kinase (ROCK) with C3 and Y-27632, respectively. Motile responses were induced in isolated guinea pig OHCs by stimulation with an 8 V/cm external alternating electrical field as 50 Hz bursts of square wave pulses (100 ms on/off). We found that LPA increased expression of PKCα and PKCζ only, with PKCα, but not PKCζ, phosphorylating the cytoskeletal protein adducin of both Ser-726 and Thr-445. Interestingly, however, inhibition of PKCα reduced adducin phosphorylation only at Ser-726. We also determined that LPA activation of a PKCα-mediated signaling pathway simultaneously enhanced OHC electromotile amplitude and cell shortening, and facilitated RhoA/ROCK/LIMK1-mediated cofilin phosphorylation. Altogether, our results suggest that PKCα-mediated signals, probably via adducin-mediated inhibition of actin-spectrin binding and cofilin-mediated depolymerization of actin filaments, play an essential role in the homeostatic regulation of OHC motility and cochlear amplification.
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Affiliation(s)
- Channy Park
- Laboratory of Auditory Cell Biology, Department of Head & Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Federico Kalinec
- Laboratory of Auditory Cell Biology, Department of Head & Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California.
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Maulucci G, Troiani D, Eramo SLM, Paciello F, Podda MV, Paludetti G, Papi M, Maiorana A, Palmieri V, De Spirito M, Fetoni AR. Time evolution of noise induced oxidation in outer hair cells: role of NAD(P)H and plasma membrane fluidity. Biochim Biophys Acta Gen Subj 2014; 1840:2192-202. [PMID: 24735797 DOI: 10.1016/j.bbagen.2014.04.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 03/25/2014] [Accepted: 04/07/2014] [Indexed: 01/24/2023]
Abstract
BACKGROUND Noise exposure impairs outer hair cells (OHCs). The common basis for OHC dysfunction and loss by acoustic over-stimulation is represented by reactive oxygen species (ROS) overload that may affect the membrane structural organization through generation of lipid peroxidation. METHODS Here we investigated in OHC different functional zones the mechanisms linking metabolic functional state (NAD(P)H intracellular distribution) to the generation of lipid peroxides and to the physical state of membranes by two photon fluorescence microscopy. RESULTS In OHCs of control animals, a more oxidized NAD(P)H redox state is associated to a less fluid plasma membrane structure. Acoustic trauma induces a topologically differentiated NAD(P)H oxidation in OHC rows, which is damped between 1 and 6h. Peroxidation occurs after ~4h from noise insult, while ROS are produced in the first 0.2h and damage cells for a period of time after noise exposure has ended (~7.5h) when a decrease of fluidity of OHC plasma membrane occurs. OHCs belonging to inner rows, characterized by a lower metabolic activity with respect to other rows, show less severe metabolic impairment. CONCLUSIONS Our data indicate that plasma membrane fluidity is related to NAD(P)H redox state and lipid peroxidation in hair cells. GENERAL SIGNIFICANCE Our results could pave the way for therapeutic intervention targeting the onset of redox umbalance.
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Affiliation(s)
| | - Diana Troiani
- Istituto di Fisiologia, Università Cattolica (UCSC), Roma, Italy.
| | | | - Fabiola Paciello
- Dipartimento di Scienze Chirurgiche per le patologie della testa e del collo, Università Cattolica (UCSC), Roma, Italy
| | | | - Gaetano Paludetti
- Dipartimento di Scienze Chirurgiche per le patologie della testa e del collo, Università Cattolica (UCSC), Roma, Italy
| | | | | | | | | | - Anna Rita Fetoni
- Dipartimento di Scienze Chirurgiche per le patologie della testa e del collo, Università Cattolica (UCSC), Roma, Italy
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