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35 results on '"Frolenkov, Gregory I."'

4. Myosins and Hearing

Author

Friedman, Thomas B., Belyantseva, Inna A., Frolenkov, Gregory I., Crusio, Wim E., Series Editor, Lambris, John D., Series Editor, Radeke, Heinfried H., Series Editor, Rezaei, Nima, Series Editor, and Coluccio, Lynne M., editor

Published
2020
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6. Calcium and Integrin-binding protein 2 (CIB2) controls force sensitivity of the mechanotransducer channels in cochlear outer hair cells

Author

Aristizábal-Ramírez, Isabel, primary, Dragich, Abigail K., additional, Giese, Arnaud P.J., additional, Sofia Zuluaga-Osorio, K., additional, Watkins, Julie, additional, Davies, Garett K., additional, Hadi, Shadan E., additional, Riazuddin, Saima, additional, Vander Kooi, Craig W., additional, Ahmed, Zubair M., additional, and Frolenkov, Gregory I., additional

Published
2023
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7. Helios is a key transcriptional regulator of outer hair cell maturation

Author

Chessum, Lauren, Matern, Maggie S., Kelly, Michael C., Johnson, Stuart L., Ogawa, Yoko, Milon, Beatrice, McMurray, Mark, Driver, Elizabeth C., Parker, Andrew, Song, Yang, Codner, Gemma, Esapa, Christopher T., Prescott, Jack, Trent, Graham, Wells, Sara, Dragich, Abigail K., Frolenkov, Gregory I., Kelley, Matthew W., Marcotti, Walter, Brown, Steve D. M., Elkon, Ran, Bowl, Michael R., and Hertzano, Ronna

Published
2018
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9. Unbalanced bidirectional radial stiffness gradients within the organ of Corti promoted by TRIOBP

Author

Babahosseini, Hesam, primary, Belyantseva, Inna A., additional, Yousaf, Rizwan, additional, Tona, Risa, additional, Hadi, Shadan, additional, Inagaki, Sayaka, additional, Wilson, Elizabeth, additional, Kitajiri, Shin-ichiro, additional, Frolenkov, Gregory I., additional, Friedman, Thomas B., additional, and Cartagena-Rivera, Alexander X., additional

Published
2022
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15. Modification of cell wall polysaccharide spatially controls cell division in Streptococcus mutans

Author

Zamakhaeva, Svetlana, primary, Chaton, Catherine T., additional, Rush, Jeffrey S., additional, Castro, Sowmya Ajay, additional, Yarawsky, Alexander E., additional, Herr, Andrew B., additional, van Sorge, Nina M., additional, Dorfmueller, Helge C., additional, Frolenkov, Gregory I., additional, Korotkov, Konstantin V., additional, and Korotkova, Natalia, additional

Published
2020
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16. Angular Approach Scanning Ion Conductance Microscopy

Author

Shevchuk, Andrew, Tokar, Sergiy, Gopal, Sahana, Sanchez-Alonso, Jose L., Tarasov, Andrei I., Vélez-Ortega, A. Catalina, Chiappini, Ciro, Rorsman, Patrik, Stevens, Molly M., Gorelik, Julia, Frolenkov, Gregory I., Klenerman, David, Korchev, Yuri E., Wellcome Trust, and Biotechnology and Biological Sciences Research Council (BBSRC)

Subjects
Adult, Male, Patch-Clamp Techniques, 02 Physical Sciences, Biophysics, Equipment Design, Microscopy, Scanning Probe, 06 Biological Sciences, Culture Media, Rats, Sprague-Dawley, Mice, Micromanipulation, Imaging, Three-Dimensional, Cell Biophysics, Microscopy, Electron, Scanning, Animals, Humans, Nanotechnology, Female, 03 Chemical Sciences, Cells, Cultured, HeLa Cells
Abstract

Scanning ion conductance microscopy (SICM) is a super-resolution live imaging technique that uses a glass nanopipette as an imaging probe to produce three-dimensional (3D) images of cell surface. SICM can be used to analyze cell morphology at nanoscale, follow membrane dynamics, precisely position an imaging nanopipette close to a structure of interest, and use it to obtain ion channel recordings or locally apply stimuli or drugs. Practical implementations of these SICM advantages, however, are often complicated due to the limitations of currently available SICM systems that inherited their design from other scanning probe microscopes in which the scan assembly is placed right above the specimen. Such arrangement makes the setting of optimal illumination necessary for phase contrast or the use of high magnification upright optics difficult. Here, we describe the designs that allow mounting SICM scan head on a standard patch-clamp micromanipulator and imaging the sample at an adjustable approach angle. This angle could be as shallow as the approach angle of a patch-clamp pipette between a water immersion objective and the specimen. Using this angular approach SICM, we obtained topographical images of cells grown on nontransparent nanoneedle arrays, of islets of Langerhans, and of hippocampal neurons under upright optical microscope. We also imaged previously inaccessible areas of cells such as the side surfaces of the hair cell stereocilia and the intercalated disks of isolated cardiac myocytes, and performed targeted patch-clamp recordings from the latter. Thus, our new, to our knowledge, angular approach SICM allows imaging of living cells on nontransparent substrates and a seamless integration with most patch-clamp setups on either inverted or upright microscopes, which would facilitate research in cell biophysics and physiology.

Published
2016
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17. TRIOBP-5 sculpts stereocilia rootlets and stiffens supporting cells enabling hearing

Author

Katsuno, Tatsuya, primary, Belyantseva, Inna A., additional, Cartagena-Rivera, Alexander X., additional, Ohta, Keisuke, additional, Crump, Shawn M., additional, Petralia, Ronald S., additional, Ono, Kazuya, additional, Tona, Risa, additional, Imtiaz, Ayesha, additional, Rehman, Atteeq, additional, Kiyonari, Hiroshi, additional, Kaneko, Mari, additional, Wang, Ya-Xian, additional, Abe, Takaya, additional, Ikeya, Makoto, additional, Fenollar-Ferrer, Cristina, additional, Riordan, Gavin P., additional, Wilson, Elisabeth A., additional, Fitzgerald, Tracy S., additional, Segawa, Kohei, additional, Omori, Koichi, additional, Ito, Juichi, additional, Frolenkov, Gregory I., additional, Friedman, Thomas B., additional, and Kitajiri, Shin-ichiro, additional

Published
2019
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19. CIB2 interacts with TMC1 and TMC2 and is essential for mechanotransduction in auditory hair cells

Author

Giese, Arnaud P. J., primary, Tang, Yi-Quan, additional, Sinha, Ghanshyam P., additional, Bowl, Michael R., additional, Goldring, Adam C., additional, Parker, Andrew, additional, Freeman, Mary J., additional, Brown, Steve D. M., additional, Riazuddin, Saima, additional, Fettiplace, Robert, additional, Schafer, William R., additional, Frolenkov, Gregory I., additional, and Ahmed, Zubair M., additional

Published
2017
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23. Correction: A Novel C-Terminal CIB2 (Calcium and Integrin Binding Protein 2) Mutation Associated with Non-Syndromic Hearing Loss in a Hispanic Family

Author

Patel, Kunjan, primary, Giese, Arnaud P., additional, Grossheim, J. M., additional, Hegde, Rashmi S., additional, Delio, Maria, additional, Samanich, Joy, additional, Riazuddin, Saima, additional, Frolenkov, Gregory I., additional, Cai, Jinlu, additional, Ahmed, Zubair M., additional, and Morrow, Bernice E., additional

Published
2015
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24. RFX transcription factors are essential for hearing in mice

Author

Elkon, Ran, primary, Milon, Beatrice, additional, Morrison, Laura, additional, Shah, Manan, additional, Vijayakumar, Sarath, additional, Racherla, Manoj, additional, Leitch, Carmen C., additional, Silipino, Lorna, additional, Hadi, Shadan, additional, Weiss-Gayet, Michèle, additional, Barras, Emmanuèle, additional, Schmid, Christoph D., additional, Ait-Lounis, Aouatef, additional, Barnes, Ashley, additional, Song, Yang, additional, Eisenman, David J., additional, Eliyahu, Efrat, additional, Frolenkov, Gregory I., additional, Strome, Scott E., additional, Durand, Bénédicte, additional, Zaghloul, Norann A., additional, Jones, Sherri M., additional, Reith, Walter, additional, and Hertzano, Ronna, additional

Published
2015
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25. A Novel C-Terminal CIB2 (Calcium and Integrin Binding Protein 2) Mutation Associated with Non-Syndromic Hearing Loss in a Hispanic Family

Author

Patel, Kunjan, primary, Giese, Arnaud P., additional, Grossheim, J. M., additional, Hegde, Rashima S., additional, Delio, Maria, additional, Samanich, Joy, additional, Riazuddin, Saima, additional, Frolenkov, Gregory I., additional, Cai, Jinlu, additional, Ahmed, Zubair M., additional, and Morrow, Bernice E., additional

Published
2015
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28. Novel and recurrent CIB2 variants, associated with nonsyndromic deafness, do not affect calcium buffering and localization in hair cells

Author

Seco, Celia Zazo, primary, Giese, Arnaud P, additional, Shafique, Sobia, additional, Schraders, Margit, additional, Oonk, Anne M M, additional, Grossheim, Mike, additional, Oostrik, Jaap, additional, Strom, Tim, additional, Hegde, Rashmi, additional, van Wijk, Erwin, additional, Frolenkov, Gregory I, additional, Azam, Maleeha, additional, Yntema, Helger G, additional, Free, Rolien H, additional, Riazuddin, Saima, additional, Verheij, Joke B G M, additional, Admiraal, Ronald J, additional, Qamar, Raheel, additional, Ahmed, Zubair M, additional, and Kremer, Hannie, additional

Published
2015
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30. The 133-kDa N-terminal domain enables myosin 15 to maintain mechanotransducing stereocilia and is essential for hearing.

Author

Qing Fang, Indzhykulian, Artur A., Mustapha, Mirna, Riordan, Gavin P., Dolan, David F., Friedman, Thomas B., Belyantseva, Inna A., Frolenkov, Gregory I., Camper, Sally A., and Bird, Jonathan E.

Subjects
MYOSIN, HEARING, MECHANOTRANSDUCTION (Cytology)
Abstract

The article discusses a study which shows the significant role of myosin-15 isoforms in the maintenance of hair cell stereocilia assembly and critical for the sense of hearing.

Published
2015
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31. Novel and recurrent CIB2 variants, associated with nonsyndromic deafness, do not affect calcium buffering and localization in hair cells

Author

Seco, Celia Zazo, Giese, Arnaud P, Shafique, Sobia, Schraders, Margit, Oonk, Anne M M, Grossheim, Mike, Oostrik, Jaap, Strom, Tim, Hegde, Rashmi, van Wijk, Erwin, Frolenkov, Gregory I, Azam, Maleeha, Yntema, Helger G, Free, Rolien H, Riazuddin, Saima, Verheij, Joke B G M, Admiraal, Ronald J, Qamar, Raheel, Ahmed, Zubair M, and Kremer, Hannie

Abstract

Variants in CIB2 can underlie either Usher syndrome type I (USH1J) or nonsyndromic hearing impairment (NSHI) (DFNB48). Here, a novel homozygous missense variant c.196C>T and compound heterozygous variants, c.[97C>T];[196C>T], were found, respectively, in two unrelated families of Dutch origin. Besides, the previously reported c.272 T>C functional missense variant in CIB2 was identified in two families of Pakistani origin. The missense variants are demonstrated not to affect subcellular localization of CIB2 in vestibular hair cells in ex vivo expression experiments. Furthermore, these variants do not affect the ATP-induced calcium responses in COS-7 cells. However, based on the residues affected, the variants are suggested to alter αIIβ integrin binding. HI was nonsyndromic in all four families. However, deafness segregating with the c.272T>C variant in one Pakistani family is remarkably less severe than that in all other families with this mutation. Our results contribute to the insight in genotype–phenotype correlations of CIB2 mutations.

Published
2016
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32. RFX transcription factors are essential for hearing in mice.

Author

Elkon, Ran, Milon, Beatrice, Morrison, Laura, Shah, Manan, Vijayakumar, Sarath, Racherla, Manoj, Leitch, Carmen C., Silipino, Lorna, Hadi, Shadan, Weiss-Gayet, Michèle, Barras, Emmanuèle, Schmid, Christoph D., Ait-Lounis, Aouatef, Barnes, Ashley, Song, Yang, Eisenman, David J., Eliyahu, Efrat, Frolenkov, Gregory I., Strome, Scott E., and Durand, Bénédicte

Subjects
DEAFNESS, HAIR cells, MECHANORECEPTORS, SENSORY receptors, KNOCKOUT mice
Abstract

Sensorineural hearing loss is a common and currently irreversible disorder, because mammalian hair cells (HCs) do not regenerate and current stem cell and gene delivery protocols result only in immature HC-like cells. Importantly, although the transcriptional regulators of embryonic HC development have been described, little is known about the postnatal regulators of maturating HCs. Here we apply a cell type-specific functional genomic analysis to the transcriptomes of auditory and vestibular sensory epithelia from early postnatal mice. We identify RFX transcription factors as essential and evolutionarily conserved regulators of the HC-specific transcriptomes, and detect Rfx1,2,3,5 and 7 in the developing HCs. To understand the role of RFX in hearing, we generate Rfx1/3 conditional knockout mice. We show that these mice are deaf secondary to rapid loss of initially well-formed outer HCs. These data identify an essential role for RFX in hearing and survival of the terminally differentiating outer HCs. [ABSTRACT FROM AUTHOR]

Published
2015
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33. Imaging analysis reveals budding of filamentous human metapneumovirus virions and direct transfer of inclusion bodies through intercellular extensions.

Author

El Najjar F, Castillo SR, Moncman CL, Wu C-Y, Isla E, Velez Ortega AC, Frolenkov GI, Cifuentes-Munoz N, and Dutch RE

Subjects
Humans, Aged, Cell Line, Cytoskeleton, Inclusion Bodies, Virion, Metapneumovirus
Abstract

Importance: Human metapneumovirus is an important respiratory pathogen that causes significant morbidity and mortality, particularly in the very young, the elderly, and the immunosuppressed. However, the molecular details of how this virus spreads to new target cells are unclear. This work provides important new information on the formation of filamentous structures that are consistent with virus particles and adds critical new insight into the structure of extensions between cells that form during infection. In addition, it demonstrates for the first time the movement of viral replication centers through these intercellular extensions, representing a new mode of direct cell-to-cell spread that may be applicable to other viral systems., Competing Interests: The authors declare no conflict of interest.

Published
2023
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34. Calcium and Integrin-binding protein 2 (CIB2) controls force sensitivity of the mechanotransducer channels in cochlear outer hair cells.

Author

Aristizábal-Ramírez I, Dragich AK, Giese APJ, Sofia Zuluaga-Osorio K, Watkins J, Davies GK, Hadi SE, Riazuddin S, Vander Kooi CW, Ahmed ZM, and Frolenkov GI

Abstract

Calcium and Integrin-Binding Protein 2 (CIB2) is an essential subunit of the mechano-electrical transduction (MET) complex in mammalian auditory hair cells. CIB2 binds to pore-forming subunits of the MET channel, TMC1/2 and is required for their transport and/or retention at the tips of mechanosensory stereocilia. Since genetic ablation of CIB2 results in complete loss of MET currents, the exact role of CIB2 in the MET complex remains elusive. Here, we generated a new mouse strain with deafness-causing p.R186W mutation in Cib2 and recorded small but still measurable MET currents in the cochlear outer hair cells. We found that R186W variant causes increase of the resting open probability of MET channels, steeper MET current dependence on hair bundle deflection (I-X curve), loss of fast adaptation, and increased leftward shifts of I-X curves upon hair cell depolarization. Combined with AlphaFold2 prediction that R186W disrupts one of the multiple interacting sites between CIB2 and TMC1/2, our data suggest that CIB2 mechanically constraints TMC1/2 conformations to ensure proper force sensitivity and dynamic range of the MET channels. Using a custom piezo-driven stiff probe deflecting the hair bundles in less than 10 µs, we also found that R186W variant slows down the activation of MET channels. This phenomenon, however, is unlikely to be due to direct effect on MET channels, since we also observed R186W-evoked disruption of the electron-dense material at the tips of mechanotransducing stereocilia and the loss of membrane-shaping BAIAP2L2 protein from the same location. We concluded that R186W variant of CIB2 disrupts force sensitivity of the MET channels and force transmission to these channels.

Published
2023
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35. Visualization of Live Cochlear Stereocilia at a Nanoscale Resolution Using Hopping Probe Ion Conductance Microscopy.

Author

Vélez-Ortega AC and Frolenkov GI

Subjects
Animals, Electric Conductivity, Mice, Microscopy, Scanning Probe methods, Nanotechnology instrumentation, Rats, Cochlea ultrastructure, Microscopy, Scanning Probe instrumentation, Stereocilia ultrastructure
Abstract

The mechanosensory apparatus that detects sound-induced vibrations in the cochlea is located on the apex of the auditory sensory hair cells and it is made up of actin-filled projections, called stereocilia. In young rodents, stereocilia bundles of auditory hair cells consist of 3-4 rows of stereocilia of decreasing height and varying thickness. Morphological studies of the auditory stereocilia bundles in live hair cells have been challenging because the diameter of each stereocilium is near or below the resolution limit of optical microscopy. In theory, scanning probe microscopy techniques, such as atomic force microscopy, could visualize the surface of a living cell at a nanoscale resolution. However, their implementations for hair cell imaging have been largely unsuccessful because the probe usually damages the bundle and disrupts the bundle cohesiveness during imaging. We overcome these limitations by using hopping probe ion conductance microscopy (HPICM), a non-contact scanning probe technique that is ideally suited for the imaging of live cells with a complex topography. Organ of Corti explants are placed in a physiological solution and then a glass nanopipette-which is connected to a 3D-positioning piezoelectric system and to a patch clamp amplifier-is used to scan the surface of the live hair cells at nanometer resolution without ever touching the cell surface.Here, we provide a detailed protocol for the imaging of mouse or rat stereocilia bundles in live auditory hair cells using HPICM. We provide information about the fabrication of the nanopipettes, the calibration of the HPICM setup, the parameters we have optimized for the imaging of live stereocilia bundles and, lastly, a few basic image post-processing manipulations.

Published
2016
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