Federico Kalinec

House Research Institute, Los Angeles, CA, USA

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Publications (19)51.01 Total impact

  • Article: Microdomains Shift and Rotate in the Lateral Wall of Cochlear Outer Hair Cells.
    Rei Kitani, Channy Park, Federico Kalinec
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    ABSTRACT: Outer hair cell (OHC) electromotility, a response consisting of reversible changes in cell length and diameter induced by electrical stimulation, confers remarkable sensitivity and frequency resolution to the mammalian inner ear. Looking for a better understanding of this mechanism, we labeled isolated guinea pig OHCs with microspheres and, using high-speed video recording, investigated their movements at the apical, mid, and basal regions of osmotically and electrically stimulated cells. After hypoosmotic challenge, OHCs shortened and their diameter increased, with microspheres moving always toward the central plane; iso-osmolarity returned OHCs to their original shape and microspheres to their original positions. Under electrical stimulation, microspheres exhibited robust movements, with their displacement vectors changing in direction from random to parallel to the longitudinal axis of the cells with peak reorientation speeds of up to 6 rad/s and returning to random after 5 min without stimulation. Alterations in plasma-membrane cholesterol levels as well as cytoskeleton integrity affected microsphere responses. We concluded that microspheres attach to different molecular microdomains, and these microdomains are able to shift and rotate in the plane of the OHC lateral wall with a dynamics tightly regulated by membrane lipid composition and the cortical cytoskeleton.
    Biophysical Journal 01/2013; 104(1):8-18. · 3.65 Impact Factor
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    Article: Deiters cells tread a narrow path--the Deiters cells-basilar membrane junction.
    Arya Parsa, Paul Webster, Federico Kalinec
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    ABSTRACT: Deiters cells extend from the basilar membrane to the reticular lamina and, together with pillar cells and outer hair cells, structurally define the micro-architecture of the organ of Corti. Studying vibrotome sections of the mouse organ of Corti with confocal and scanning electron microscopy we found that the basal pole of every Deiters cell, independently of their position in the organ of Corti and along the cochlear spiral, attached to the basilar membrane within a 15.1 ± 0.3 μm-wide stripe running the length of the cochlear spiral adjacent to the row of outer pillar cells. All Deiters cells' basal poles had similar diameter and general morphology, and distributed on the stripe in a precise arrangement with a center-to-center distance of 7.1 ± 0.3 μm between neighbor cells of the same row and 5.9 ± 0.4 μm for neighbor cells in adjacent rows. Complete detachment of Deiters cells revealed an elliptical imprint on the top surface of the basilar membrane consisting of a smaller central structure with a very smooth surface surrounded by a rougher area, suggesting the presence of two different anchoring junctions. These previously unidentified morphological features of Deiters cells could be critical for the mechanical response of the organ of Corti.
    Hearing research 05/2012; 290(1-2):13-20. · 2.18 Impact Factor
  • Article: In vitro and in vivo models of drug ototoxicity: studying the mechanisms of a clinical problem.
    Joshua G Yorgason, William Luxford, Federico Kalinec
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    ABSTRACT: INTRODUCTION: Drug ototoxicity represents one of the main preventable causes of deafness. Ototoxicity is a trait shared by aminoglycoside and macrolide antibiotics, antimalarial medications, loop diuretics, platinum-based chemotherapeutic agents, some NSAIDs and most recently described, acetaminophen when abused with narcotic medication. These medications are prescribed despite their side effects, which includes inner ear toxicity, because they are life-saving drugs or there is a lack of better treatment. AREAS COVERED: This review will discuss in vitro and in vivo models of ototoxicity highlighting recently published ototoxicity research. The reader will learn the strengths and limitations of different ototoxicity models and what molecular insights have been gained from their application. A better understanding of the cellular mechanisms of these ototoxins will help in the discovery of ways to prevent and treat hearing loss associated with ototoxic medications. EXPERT OPINION: There are benefits to both in vitro and in vivo models of ototoxicity. Research of a particular medication and its ototoxic mechanisms should draw from several models, enabling a better answer to the clinical question of prevention and treatment of inner ear drug toxicity.
    Expert Opinion on Drug Metabolism &amp Toxicology 12/2011; 7(12):1521-34. · 3.12 Impact Factor
  • Article: Motile responses of cochlear outer hair cells stimulated with an alternating electrical field.
    Rei Kitani, Seiji Kakehata, Federico Kalinec
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    ABSTRACT: The goal of the present study was to evaluate and characterize the motile responses of guinea pig OHCs, stimulated at frequencies varying from 50 Hz to 4 kHz, using high-definition, high-speed video recording and fully automatic image analysis software. Cells stimulated in continuous, burst and sweeping modes with an external alternating electrical field showed robust fast and slow motility, which were dependent on frequency, mode and intensity of stimulation. In response to continuous stimulation, electromotile amplitude ranged from 0.3% to 3.2% of total cell length, whereas cell length usually decreased in amounts varying from 0.1% to 4.3%. Electromotile amplitude in OHCs stimulated with square wave's sweeps was near constant up to 200 Hz, progressively decreased between 200 Hz and 2 kHz, and then remained constant up to 4 kHz. In continuous and burst modes electromotility followed cycle-by-cycle the electrical stimulus, but it required 1-2 s to fully develop and reach maximal amplitude. Instead, slow cell length changes started about 0.6 s after the beginning and continuously developed up to 3 s after the end of electrical stimulation. Incubation of OHCs with 10 mM salicylate affected electromotility but not slow motility, whereas incubation with 3 mM gadolinium affected both. Thus, combination of external electrical stimulation, high-speed video recording and advanced image analysis software provides information about OHC motile responses at acoustic frequencies with an unprecedented detail, opening new areas of research in the field of OHC mechanics.
    Hearing research 05/2011; 280(1-2):209-18. · 2.18 Impact Factor
  • Article: Linking LIMK1 deficiency to hyperacusis and progressive hearing loss in individuals with Williams syndrome.
    Nozomu Matsumoto, Rei Kitani, Federico Kalinec
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    ABSTRACT: Williams syndrome (a.k.a. Williams-Beuren Syndrome) is a multisystem disorder caused by the hemizygous deletion of a 1.6 Mb region at 7q11.23 encompassing about 26 genes, including that encoding LIM kinase 1 (LIMK1). Individuals with Williams Syndrome manifest hyperacusis and progressive hearing loss, and hyperacusis early onset suggests that it could be associated with one of the deleted genes. Based on our results about the critical role of LIM kinases in the regulation of the motile responses of cochlear outer hair cells (OHC) and cochlear amplification, we propose here that a reduced expression of LIMK1 in OHC would be the major underlying cause of the hyperacusis and progressive hearing loss observed in patients with Williams Syndrome. Moreover, we propose a novel model of gain-control for cochlear amplification based on LIMK-mediated regulation of OHC's slow motility.
    Communicative & integrative biology 03/2011; 4(2):208-10.
  • Article: Investigating outer hair cell motility with a combination of external alternating electrical field stimulation and high-speed image analysis.
    Rei Kitani, Federico Kalinec
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    ABSTRACT: OHCs are cylindrical sensorimotor cells located in the Organ of Corti, the auditory organ inside the mammalian inner ear. The name "hair cells" derives from their characteristic apical bundle of stereocilia, a critical element for detection and transduction of sound energy. OHCs are able to change shape -elongate, shorten and bend- in response to electrical, mechanical and chemical stimulation, a motor response considered crucial for cochlear amplification of acoustic signals. OHC stimulation induces two different motile responses: i) electromotility, a.k.a fast motility, changes in length in the microsecond range derived from electrically-driven conformational changes in motor proteins densely packed in OHC plasma membrane, and ii) slow motility, shape changes in the millisecond to seconds range involving cytoskeletal reorganization. OHC bending is associated with electromotility, and result either from an asymmetric distribution of motor proteins in the lateral plasma membrane, or asymmetric electrical stimulation of those motor proteins (e.g., with an electrical field perpendicular to the long axis of the cells). Mechanical and chemical stimuli induce essentially slow motile responses, even though changes in the ionic conditions of the cells and/or their environment can also stimulate the plasma membrane-embedded motor proteins. Since OHC motile responses are an essential component of the cochlear amplifier, the qualitative and quantitative analysis of these motile responses at acoustic frequencies (roughly from 20 Hz to 20 kHz in humans) is a very important matter in the field of hearing research. The development of new imaging technology combining high-speed videocameras, LED-based illumination systems, and sophisticated image analysis software now provides the ability to perform reliable qualitative and quantitative studies of the motile response of isolated OHCs to an external alternating electrical field (EAEF). This is a simple and non-invasive technique that circumvents most of the limitations of previous approaches. Moreover, the LED-based illumination system provides extreme brightness with insignificant thermal effects on the samples and, because of the use of video microscopy, optical resolution is at least 10-fold higher than with conventional light microscopy techniques. For instance, with the experimental setup described here, changes in cell length of about 20 nm can be routinely and reliably detected at frequencies of 10 kHz, and this resolution can be further improved at lower frequencies. We are confident that this experimental approach will help to extend our understanding of the cellular and molecular mechanisms underlying OHC motility.
    Journal of Visualized Experiments 01/2011;
  • Article: Pivotal role of actin depolymerization in the regulation of cochlear outer hair cell motility.
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    ABSTRACT: Cochlear outer hair cells undergo reversible changes in shape when externally stimulated. This response, known as OHC motility, is a central component of the cochlear amplifier, the mechanism responsible for the high sensitivity of mammalian hearing. We report that actin depolymerization, as regulated by activation/inhibition of LIMK/cofilin-mediated pathways, has a pivotal role in OHC motility. LIMK-mediated cofilin phosphorylation, which inhibits the actin depolymerizing activity of this protein, increases both electromotile amplitude and total length of guinea pig OHCs. In contrast, a decrease in cofilin phosphorylation reduces both OHC electromotile amplitude and OHC length. Experiments with acetylcholine and lysophosphatidic acid indicate that the effects of these agents on OHC motility are associated with regulation of cofilin phosphorylation via different signaling cascades. On the other hand, nonlinear capacitance measurements confirmed that all observed changes in OHC motile response were independent of the performance of the motor protein prestin. Altogether, these results strongly support the hypothesis that the cytoskeleton has a major role in the regulation of OHC motility, and identify actin depolymerization as a key process for modulating cochlear amplification.
    Biophysical Journal 10/2010; 99(7):2067-76. · 3.65 Impact Factor
  • Article: Acetaminophen ototoxicity after acetaminophen/hydrocodone abuse: evidence from two parallel in vitro mouse models.
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    ABSTRACT: Acetaminophen/hydrocodone, a commonly used analgesic preparation, has been linked to rapidly progressing sensorineural hearing loss in human patients. The cellular and molecular mechanisms underlying the ototoxic effects of this drug combination are currently unknown, but are usually associated with high doses of hydrocodone. This study was aimed at identifying the specific agent responsible for hearing loss from toxic killing of cochlear sensory cells. Dose-response study. University laboratory and private research facility. Math1 green fluorescent protein neonatal mouse cochlear cultures as well as a mouse auditory cell line (HEI-OC1) were exposed in vitro to different concentrations of acetaminophen, hydromorphone (the active metabolite of hydrocodone), and the micronutrient L-carnitine, either alone or combined. Using fluorescent and light microscopy, we quantified the sensory hair cells from a 600-microm basal segment before and after treatment. Acetaminophen/hydrocodone-induced apoptosis of HEI-OC1 was evaluated by caspase 3-activation studies. Statistically significant cell survival was determined with Student t test and analysis of variance. Cell death was associated mainly with exposure to acetaminophen, was slightly potentiated when combined with hydromorphone, and was partially prevented by L-carnitine. Exposure to hydrocodone or hydromorphone alone failed to kill either cochlear hair cells or HEI-OC1 cells. Our findings point to acetaminophen, rather than hydrocodone, as the primary cytotoxic agent. Hydrocodone, however, may work synergistically with acetaminophen, increasing the damage to auditory cells. These findings are an important first step toward understanding the mechanism of acetaminophen/hydrocodone ototoxicity and may lead to future treatment strategies for hearing loss from ototoxic medications.
    Otolaryngology Head and Neck Surgery 06/2010; 142(6):814-9, 819.e1-2. · 1.72 Impact Factor
  • Article: Apoptosis in the OC-k3 Immortalized Cell Line Treated with Different Agents: Apoptosis en linea celular OC k3 inmortalizada, tratada con diferentes agentes
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    ABSTRACT: The aim of this study is to outline the mechanisms leading cochlear cells to die. We utilized an immortalized cell line (OC-k3 cells) derived from the organ of Corti of transgenic mice in order to perform in-depth biochemical studies with no limitations on sample size and number. We probed these cells with cisplatin and gentamicin, two drugs which display in vivo undesired ototoxic side-effects. We investigated cell viability, reactive oxygen species (ROS) production and glutathione (GSH) levels and tested the effects of different concentrations of cisplatin and gentamicin from 0 to 48 h. Results show that cells undergo a dose-and treatment-time-dependent apoptosis characterized by nuclear fragmentation, integrity of the cell membrane and mitochondria, and absence of DNA endonuclease activity. During the early part of treatment, ROS production increases and intracellular GSH decreases, probably due to the activation of protein kinase Ca. Use of antioxidants such as acetylcysteine, GSH and vitamin C rescues cells from apoptosis almost completely. Overall, these data indicate that ROS generation might play a central role in inducing inner ear cell apoptosis and may have an additive role in the ageing process.
    07/2009; 40(6):327-335.
  • Article: Understanding drug ototoxicity: molecular insights for prevention and clinical management.
    Joshua G Yorgason, Jose N Fayad, Federico Kalinec
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    ABSTRACT: Ototoxicity is a trait shared by aminoglycoside and macrolide antibiotics, loop diuretics, platinum-based chemotherapeutic agents, some NSAIDs and antimalarial medications. Because their benefits in combating certain life-threatening diseases often outweigh the risks, the use of these ototoxic drugs cannot simply be avoided. In this review, the authors discuss some of the most frequently used ototoxic drugs and what is currently known about the cell and molecular mechanisms underlying their noxious effects. The authors also provide suggestions for the clinical management of ototoxic medications, including ototoxic detection and drug monitoring. Understanding the mechanisms of drug ototoxicity may lead to new strategies for preventing and curing drug-induced hearing loss, as well as developing new pharmacological drugs with less toxic side effects.
    Expert Opinion on Drug Safety 06/2006; 5(3):383-99. · 3.02 Impact Factor
  • Article: Extraction of prestin-dependent and prestin-independent components from complex motile responses in guinea pig outer hair cells.
    Nozomu Matsumoto, Federico Kalinec
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    ABSTRACT: Electromotility of cochlear outer hair cells (OHC) is associated with conformational changes in the integral membrane protein prestin. We have recently reported that electrical stimulation evokes significant prestin-dependent changes in the length, width, and area of the longitudinal section of OHCs, but not in their volume. In contrast, prestin-independent responses elicited at constant membrane potential are associated with changes in cell length, width, and volume without significant changes in their longitudinal section area. In this report we describe a novel analytical technique, based on a simple theoretical model and continuous measurement of changes in cell length and longitudinal section area, to evaluate the contribution of each one of these mechanisms to the motile response of OHCs. We demonstrate that if the relative change in OHC length (L) during the motile response is expressed as L = A2 x V(-1) (with A and V being the relative changes in longitudinal section area and volume, respectively), A2 will describe the contribution of the prestin-dependent mechanism whereas V(-1) will describe the contribution of the prestin-independent mechanism. Thus, relative changes in any two of these cellular morphological parameters (L, A, or V) would be necessary and sufficient for characterizing any OHC motile response. This simple approach provides access to information previously unavailable, and may become a novel and important tool for increasing our understanding of the cellular and molecular mechanisms of OHC motility.
    Biophysical Journal 01/2006; 89(6):4343-51. · 3.65 Impact Factor
  • Article: Prestin-dependent and prestin-independent motility of guinea pig outer hair cells.
    Nozomu Matsumoto, Federico Kalinec
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    ABSTRACT: The motile response of isolated guinea pig outer hair cells (OHCs) was investigated using a combination of whole-cell patch clamp recording and continuous video image analysis. OHC's length, width, and area were measured from video images and the cell volume estimated from these values. Morphological data was then correlated with electrophysiological recordings of whole-cell current, membrane potential and voltage-dependent non-linear capacitance. Electromotility was evoked either by manipulating the membrane potential under voltage-clamp conditions or by exposing OHCs to high K+ solutions. Other motile responses were investigated in voltage-clamp experiments at constant holding potential, or exposing OHCs to solutions that did not affect the membrane potential. We found that electrical stimulation evoked voltage-dependent changes in OHC's length, width and area but not in cell volume regardless of the time course of stimulation. Moreover, changes in cell area were always associated with both voltage-dependent motility and non-linear capacitance, suggesting prestin dependency. In contrast, voltage-independent motile responses at constant membrane potential, which are presumed to be prestin-independent, were associated with changes in cell length, width and volume without significant changes in area. Area measurements, then, become a tool to investigate the simultaneous occurrence of both prestin-dependent and prestin-independent OHC motilities, and for evaluating the individual contribution of each mechanism to the total cell movement.
    Hearing Research 11/2005; 208(1-2):1-13. · 2.70 Impact Factor
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    Article: Pivotal role of Harakiri in the induction and prevention of gentamicin-induced hearing loss.
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    ABSTRACT: Gentamicin is a widely used ototoxic agent. In this study, we shed light on the mechanisms underlying gentamicin-induced hearing loss. More importantly, we demonstrate in vivo and in vitro the effectiveness of a strategy for preventing drug-induced hearing loss using l-carnitine (LCAR), a safe micronutrient that plays a key role in energy metabolism and detoxification [Rebouche, C. J. & Seim, H. (1998) Annu. Rev. Nutr. 18, 39-61]. We show that LCAR prevents changes in hearing threshold and cochlear damage in newborn guinea pigs exposed to gentamicin in utero. Mechanistically, gentamicin-induced apoptosis of auditory cells is mediated by the extracellular signal-regulated kinase (ERK) 1/2 mitogen-activated protein kinase (MAPK) pathway through up-regulation of the proapoptotic factor Harakiri (Hrk). Most important, small interfering RNA (siRNA) experiments demonstrate that Hrk up-regulation is crucial for gentamicin-induced apoptosis. LCAR, in contrast, prevents both gentamicin-induced Hrk up-regulation and apoptosis acting by means of c-Jun N-terminal kinase (JNK). Together, these results outline pathways for gentamicin-induced hearing loss and its prevention and assign a key role to Hrk in these processes. Thus, our data offer a conceptual framework for designing clinical trials using a safe micronutrient, LCAR, as a simple preventive strategy for iatrogenically induced ototoxicity.
    Proceedings of the National Academy of Sciences 11/2005; 102(44):16019-24. · 9.68 Impact Factor
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    Article: Protective effect of T-type calcium channel blocker flunarizine on cisplatin-induced death of auditory cells.
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    ABSTRACT: Changes in intracellular Ca2+ level are involved in a number of intracellular events, including triggering of apoptosis. The role of intracellular calcium mobilization in cisplatin-induced hair cell death, however, is still unknown. In this study, the effect of calcium channel blocker flunarizine (Sibelium), which is used to prescribe for vertigo and tinnitus, on cisplatin-induced hair cell death was investigated in a cochlear organ of Corti-derived cell line, HEI-OC1, and the neonatal (P2) rat organ of Corti explant. Cisplatin induced apoptotic cell death showing nuclear fragmentation, DNA ladder, and TUNEL positive in both HEI-OC1 and primary organ of Corti explant. Flunarizine significantly inhibited the cisplatin-induced apoptosis. Unexpectedly, flunarizine increased the intracellular calcium ([Ca2+]i) levels of HEI-OC1. However, the protective effect of flunarizine against cisplatin was not mediated by modulation of intracellular calcium level. Treatment of cisplatin resulted in ROS generation and lipid peroxidation in HEI-OC1. Flunarizine did not attenuate ROS production but inhibited lipid peroxidation and mitochondrial permeability transition in cisplatin-treated cells. This result suggests that the protective mechanism of flunarizine on cisplatin-induced cytotoxicity is associated with direct inhibition of lipid peroxidation and mitochondrial permeability transition.
    Hearing Research 07/2005; 204(1-2):127-39. · 2.70 Impact Factor
  • Article: ROCK-dependent and ROCK-independent control of cochlear outer hair cell electromotility.
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    ABSTRACT: Outer hair cell electromotility is crucial for the proper function of the cochlear amplifier, the active process that enhances sensitivity and frequency discrimination of the mammalian ear. Previous work (Kalinec, F., Zhang, M., Urrutia, R., and Kalinec, G. (2000) J. Biol. Chem. 275, 28000-28005) has suggested a role for Rho GTPases in the regulation of outer hair cell electromotility, although the signaling pathways mediated by these enzymes remain to be established. Here we have investigated the cellular and molecular mechanisms underlying the homeostatic regulation of the electromotile response of guinea pig outer hair cells. Our findings defined a ROCK-mediated signaling cascade that continuously modulates outer hair cell electromotility by selectively targeting the cytoskeleton. A distinct ROCK-independent pathway functions as a fast resetting mechanism for this system. Neither pathway affects the function of prestin, the unique molecular motor of outer hair cells. These results extend our understanding of a basic mechanism of both normal human hearing and deafness, revealing the key role of the cytoskeleton in the regulation of outer hair cell electromotility and suggesting ROCK as a molecular target for modulating the function of the cochlear amplifier.
    Journal of Biological Chemistry 10/2003; 278(37):35644-50. · 4.77 Impact Factor
  • Article: Cisplatin-induced apoptosis in auditory cells: role of death receptor and mitochondrial pathways.
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    ABSTRACT: Cisplatin, a commonly used chemotherapeutic agent, has a major limitation due to its ototoxicity. Previous studies have shown that cisplatin induces apoptosis in auditory sensory cells, but the underlying mechanisms remain to be elucidated. In this study, cisplatin was found to induce apoptosis in a cochlear cell line, in a dose- and duration-dependent manner. Specific caspase assays revealed an early (6 h) but transient increase in caspase 8 activity, and a delayed (12 h) increase in caspase 9 activity. The enhanced caspase 8 activity was preceded by upregulation of p53 expression, and coincided with cleavage of Bid to its truncated form. This was followed temporally by activation and mitochondrial translocation of Bax, induction of mitochondrial permeability transition, release of cytochrome c into the cytosol, activation of caspase 9, and entry into the execution phase of apoptosis. Our results indicate the involvement of both the death receptor mechanisms as well as mitochondrial pathways in cisplatin-induced apoptosis of auditory cells in an in vitro model system.
    Hearing Research 01/2003; 174(1-2):45-54. · 2.70 Impact Factor
  • Article: Structural microdomains in the lateral plasma membrane of cochlear outer hair cells.
    Ming Zhang, Federico Kalinec
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    ABSTRACT: The basal and lateral regions of the plasma membrane of cochlear outer hair cells are structurally and functionally distinct. The lateral region contains thousands of motor proteins but few voltage-gated channels. The basal region, conversely, contains a high number of voltage-gated channels but is devoid of motor proteins. It has been suggested that the cortical cytoskeleton is responsible for maintaining this regional distinction. Toward elucidating the structure of the outer hair cell's electromotile mechanism, we investigated the physical organization of the lateral plasma membrane in living guinea pig outer hair cells by analyzing the distribution pattern of the anionic long-chain carbocyanine SP-DiIC18(3) within this area, before and after electrical stimulation and with an intact and a disrupted cytoskeleton. We observed punctate, intensely fluorescent patches as well as areas of weaker fluorescence, with clear local maxima and minima, upon labeling the cells with this membrane-soluble probe. This discrete distribution of SP-DilC18(3) suggests that the lateral plasma membrane of guinea pig outer hair cells may be composed of small structural domains (microdomains). Disrupting the cytoskeleton with either trypsin or toxin B from Clostridium difficile did not change this pattern of distribution, thus indicating that this treatment did not facilitate the lateral diffusion of the probes. Electrical stimulation using whole-cell patch-clamp techniques, on the other hand, induced two responses: fast motility and reversible displacement of the fluorescent probes. Both responses were inhibited by internal perfusion with salicylate, while disruption of the cytoskeleton did not inhibit OHC fast motility but affected the electrically induced redistribution of fluorescent probes. Together, these results suggest that the lateral plasma membrane of guinea pig outer hair cells contains structural microdomains and that the cytoskeleton does not appear to be playing a major role in maintaining the lateral separation of these distinct molecular regions.
    Journal of the Association for Research in Otolaryngology 10/2002; 3(3):289-301. · 2.84 Impact Factor
  • Article: A cochlear cell line as an in vitro system for drug ototoxicity screening.
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    ABSTRACT: Aminoglycoside antibiotics, loop diuretics, antineoplastic agents and other commonly used pharmacological drugs are ototoxic. Understanding of the cellular and molecular mechanisms underlying drug ototoxicity, however, has been hampered by the limited availability of inner ear tissues and drug side effects on laboratory animals. Immortalized cell lines derived from the auditory sensory organ, sensitive to ototoxic drugs and growing in environments that can be systematically manipulated, would facilitate the research directed at elucidating these mechanisms. Such immortalized cell lines could also be used to discover novel therapeutic agents for preventing drug-induced sensorineural hearing loss. Here, we report a conditionally immortalized organ of Corti-derived epithelial cell line, which shows evidence of activation of apoptosis when exposed to known ototoxic drugs. This cell line may be an excellent in vitro system to investigate the cellular and molecular mechanisms involved in ototoxicity and for screening of the potential ototoxicity or otoprotective properties of new pharmacological drugs.
    Audiology and Neurotology 8(4):177-89. · 2.46 Impact Factor
  • Article: Immunolocalization of anion exchanger 2α in auditory sensory hair cells
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    ABSTRACT: We have previously reported the isolation from a guinea pig organ of Corti cDNA library of a cDNA clone that encodes a novel isoform of the anion exchanger 2 (AE2) protein (Negrini, Rivolta, Kalinec and Kachar, 1995. Cloning of an organ of Corti anion exchanger 2 isoform with a truncated C-terminal domain. Biophys. Acta, 1236, 207–211). The deduced protein, named AE2α, has a conserved cytoplasmic domain and a short membrane domain with only two membrane spanning regions, as opposed to the fourteen present in the conventional AE2. Now, we are showing the immunolocalization and preliminary characterization of this protein using an antipeptide antibody specific for this novel AE2 isoform. In Western blots, this antibody binds to an ∼89 kDa polypeptide that corresponds to a phosphorylated protein with serines as main phosphate acceptor residues. In immunofluorescence experiments, the antibody labels the stereocilia and the lateral wall of the outer hair cells and the stereocilia of the inner hair cells. Our results suggest that AE2α is a membrane-cytoskeletal linker in regions of the hair cell, where sensory transduction mechanisms take place.
    Hearing Research.

Institutions

  • 2005–2013
    • House Research Institute
      • Cell Biology and Genetics
      Los Angeles, CA, USA
  • 2010–2011
    • Kyushu University
      Fukuoka-shi, Fukuoka-ken, Japan
    • University of Utah
      • Division of Otolaryngology
      Salt Lake City, UT, USA
  • 2005–2006
    • Los Angeles Neurosurgical Institute
      Los Angeles, CA, USA
  • 2003–2006
    • University of California, Los Angeles
      • Department of Molecular, Cell, and Developmental Biology (MCDB)
      Los Angeles, CA, USA
    • Albert Einstein College of Medicine
      • Nephrology
      New York City, NY, USA