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Leclère JC, Dulon D. Otoferlin as a multirole Ca 2+ signaling protein: from inner ear synapses to cancer pathways. Front Cell Neurosci 2023; 17:1197611. [PMID: 37538852 PMCID: PMC10394277 DOI: 10.3389/fncel.2023.1197611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 06/28/2023] [Indexed: 08/05/2023] Open
Abstract
Humans have six members of the ferlin protein family: dysferlin, myoferlin, otoferlin, fer1L4, fer1L5, and fer1L6. These proteins share common features such as multiple Ca2+-binding C2 domains, FerA domains, and membrane anchoring through their single C-terminal transmembrane domain, and are believed to play a key role in calcium-triggered membrane fusion and vesicle trafficking. Otoferlin plays a crucial role in hearing and vestibular function. In this review, we will discuss how we see otoferlin working as a Ca2+-dependent mechanical sensor regulating synaptic vesicle fusion at the hair cell ribbon synapses. Although otoferlin is also present in the central nervous system, particularly in the cortex and amygdala, its role in brain tissues remains unknown. Mutations in the OTOF gene cause one of the most frequent genetic forms of congenital deafness, DFNB9. These mutations produce severe to profound hearing loss due to a defect in synaptic excitatory glutamatergic transmission between the inner hair cells and the nerve fibers of the auditory nerve. Gene therapy protocols that allow normal rescue expression of otoferlin in hair cells have just started and are currently in pre-clinical phase. In parallel, studies have linked ferlins to cancer through their effect on cell signaling and development, allowing tumors to form and cancer cells to adapt to a hostile environment. Modulation by mechanical forces and Ca2+ signaling are key determinants of the metastatic process. Although ferlins importance in cancer has not been extensively studied, data show that otoferlin expression is significantly associated with survival in specific cancer types, including clear cell and papillary cell renal carcinoma, and urothelial bladder cancer. These findings indicate a role for otoferlin in the carcinogenesis of these tumors, which requires further investigation to confirm and understand its exact role, particularly as it varies by tumor site. Targeting this protein may lead to new cancer therapies.
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Affiliation(s)
- Jean-Christophe Leclère
- Department of Head and Neck Surgery, Brest University Hospital, Brest, France
- Laboratory of Neurophysiologie de la Synapse Auditive, Université de Bordeaux, Bordeaux, France
| | - Didier Dulon
- Laboratory of Neurophysiologie de la Synapse Auditive, Université de Bordeaux, Bordeaux, France
- Institut de l’Audition, Institut Pasteur & INSERM UA06, Paris, France
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2
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Drescher DG, Drescher MJ, Selvakumar D, Annam NP. Analysis of Dysferlin Direct Interactions with Putative Repair Proteins Links Apoptotic Signaling to Ca 2+ Elevation via PDCD6 and FKBP8. Int J Mol Sci 2023; 24:4707. [PMID: 36902136 PMCID: PMC10002499 DOI: 10.3390/ijms24054707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Revised: 02/19/2023] [Accepted: 02/24/2023] [Indexed: 03/05/2023] Open
Abstract
Quantitative surface plasmon resonance (SPR) was utilized to determine binding strength and calcium dependence of direct interactions between dysferlin and proteins likely to mediate skeletal muscle repair, interrupted in limb girdle muscular dystrophy type 2B/R2. Dysferlin canonical C2A (cC2A) and C2F/G domains directly interacted with annexin A1, calpain-3, caveolin-3, affixin, AHNAK1, syntaxin-4, and mitsugumin-53, with cC2A the primary target and C2F lesser involved, overall demonstrating positive calcium dependence. Dysferlin C2 pairings alone showed negative calcium dependence in almost all cases. Like otoferlin, dysferlin directly interacted via its carboxy terminus with FKBP8, an anti-apoptotic outer mitochondrial membrane protein, and via its C2DE domain with apoptosis-linked gene (ALG-2/PDCD6), linking anti-apoptosis with apoptosis. Confocal Z-stack immunofluorescence confirmed co-compartmentalization of PDCD6 and FKBP8 at the sarcolemmal membrane. Our evidence supports the hypothesis that prior to injury, dysferlin C2 domains self-interact and give rise to a folded, compact structure as indicated for otoferlin. With elevation of intracellular Ca2+ in injury, dysferlin would unfold and expose the cC2A domain for interaction with annexin A1, calpain-3, mitsugumin 53, affixin, and caveolin-3, and dysferlin would realign from its interactions with PDCD6 at basal calcium levels to interact strongly with FKBP8, an intramolecular rearrangement facilitating membrane repair.
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Affiliation(s)
- Dennis G. Drescher
- Laboratory of Bio-otology, Department of Otolaryngology, Wayne State University School of Medicine, Detroit, MI 48201, USA
- Department of Biochemistry, Microbiology and Immunology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Marian J. Drescher
- Laboratory of Bio-otology, Department of Otolaryngology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Dakshnamurthy Selvakumar
- Laboratory of Bio-otology, Department of Otolaryngology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Neeraja P. Annam
- Laboratory of Bio-otology, Department of Otolaryngology, Wayne State University School of Medicine, Detroit, MI 48201, USA
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3
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Mukherjee D, Kanold PO. Changing subplate circuits: Early activity dependent circuit plasticity. Front Cell Neurosci 2023; 16:1067365. [PMID: 36713777 PMCID: PMC9874351 DOI: 10.3389/fncel.2022.1067365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 12/16/2022] [Indexed: 01/12/2023] Open
Abstract
Early neural activity in the developing sensory system comprises spontaneous bursts of patterned activity, which is fundamental for sculpting and refinement of immature cortical connections. The crude early connections that are initially refined by spontaneous activity, are further elaborated by sensory-driven activity from the periphery such that orderly and mature connections are established for the proper functioning of the cortices. Subplate neurons (SPNs) are one of the first-born mature neurons that are transiently present during early development, the period of heightened activity-dependent plasticity. SPNs are well integrated within the developing sensory cortices. Their structural and functional properties such as relative mature intrinsic membrane properties, heightened connectivity via chemical and electrical synapses, robust activation by neuromodulatory inputs-place them in an ideal position to serve as crucial elements in monitoring and regulating spontaneous endogenous network activity. Moreover, SPNs are the earliest substrates to receive early sensory-driven activity from the periphery and are involved in its modulation, amplification, and transmission before the maturation of the direct adult-like thalamocortical connectivity. Consequently, SPNs are vulnerable to sensory manipulations in the periphery. A broad range of early sensory deprivations alters SPN circuit organization and functions that might be associated with long term neurodevelopmental and psychiatric disorders. Here we provide a comprehensive overview of SPN function in activity-dependent development during early life and integrate recent findings on the impact of early sensory deprivation on SPNs that could eventually lead to neurodevelopmental disorders.
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Affiliation(s)
- Didhiti Mukherjee
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States
| | - Patrick O. Kanold
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States,Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD, United States,*Correspondence: Patrick O. Kanold ✉
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4
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Myosin VI Haploinsufficiency Reduced Hearing Ability in Mice. Neuroscience 2021; 478:100-111. [PMID: 34619316 DOI: 10.1016/j.neuroscience.2021.09.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 09/10/2021] [Accepted: 09/27/2021] [Indexed: 11/22/2022]
Abstract
In human, myosin VI (MYO6) haploinsufficiency causes postlingual progressive hearing loss. Because the usefulness of mouse models remains unclear, we produced novel Myo6 null (-/-) mutant mice and analyzed the hearing phenotypes of Myo6+/- (+/-) heterozygous mutants. We first recorded and compared the auditory brainstem responses and distortion product otoacoustic emissions in control Myo6+/+ (+/+) wild-type and +/- mice. These hearing phenotypes of +/- mice were mild; however, we confirmed that +/- mice developed progressive hearing loss. In particular, the hearing loss of female +/- mice progressed faster than that of male +/- mice. The stereocilia bundles of +/- mice exhibited progressive taper loss in cochlear inner hair cells (IHCs) and outer hair cells (OHCs). The loss of OHCs in +/- heterozygotes occurred at an earlier age than in +/+ mice. In particular, the OHCs at the basal area of the cochlea were decreased in +/- mice. IHC ribbon synapses from the area at the base of the cochlea were significantly reduced in +/- mice. Thus, our study indicated that MYO6 haploinsufficiency affected the detection of sounds in mice, and we suggest that +/- mice with Myo6 null alleles are useful animal models for gene therapy and drug treatment in patients with progressive hearing loss due to MYO6 haploinsufficiency.
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Mukherjee D, Meng X, Kao JPY, Kanold PO. Impaired Hearing and Altered Subplate Circuits During the First and Second Postnatal Weeks of Otoferlin-Deficient Mice. Cereb Cortex 2021; 32:2816-2830. [PMID: 34849612 DOI: 10.1093/cercor/bhab383] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 09/23/2021] [Accepted: 09/25/2021] [Indexed: 02/01/2023] Open
Abstract
Sensory deprivation from the periphery impacts cortical development. Otoferlin deficiency leads to impaired cochlear synaptic transmission and is associated with progressive hearing loss in adults. However, it remains elusive how sensory deprivation due to otoferlin deficiency impacts the early development of the auditory cortex (ACX) especially before the onset of low threshold hearing. To test that, we performed in vivo imaging of the ACX in awake mice lacking otoferlin (Otof-/-) during the first and second postnatal weeks and found that spontaneous and sound-driven cortical activity were progressively impaired. We then characterized the effects on developing auditory cortical circuits by performing in vitro recordings from subplate neurons (SPN), the first primary targets of thalamocortical inputs. We found that in Otof-/- pups, SPNs received exuberant connections from excitatory and inhibitory neurons. Moreover, as a population, SPNs showed higher similarity with respect to their circuit topology in the absence of otoferlin. Together, our results show that otoferlin deficiency results in impaired hearing and has a powerful influence on cortical connections and spontaneous activity in early development even before complete deafness. Therefore, peripheral activity has the potential to sculpt cortical structures from the earliest ages, even before hearing impairment is diagnosed.
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Affiliation(s)
- Didhiti Mukherjee
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA.,Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Xiangying Meng
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA.,Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Joseph P Y Kao
- Center for Biomedical Engineering and Technology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Patrick O Kanold
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA.,Department of Biology, University of Maryland, College Park, MD 20742, USA.,Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD 21205, USA
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Fareed M, Sharma V, Singh I, Rehman SU, Singh G, Afzal M. Whole-Exome Sequencing Reveals a Rare Variant of OTOF Gene Causing Congenital Non-syndromic Hearing Loss Among Large Muslim Families Favoring Consanguinity. Front Genet 2021; 12:641925. [PMID: 34113375 PMCID: PMC8185570 DOI: 10.3389/fgene.2021.641925] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/02/2021] [Indexed: 12/30/2022] Open
Abstract
Non-syndromic hearing loss (NSHL) is one of the most frequent auditory deficits in humans characterized by high clinical and genetic heterogeneity. Very few studies have reported the relationship between OTOF (Locus: DFNB9) and hereditary hearing loss in India. We aimed to decipher the genetic cause of prelingual NSHL in a large affected Muslim consanguineous families using whole-exome sequencing (WES). The study was performed following the guidelines and regulations of the Indian Council of Medical Research (ICMR), New Delhi. The population was identified from Jammu and Kashmir, the Northernmost part of India. Near about 100 individuals were born deaf-mute in the village of 3,000 inhabitants. A total of 103 individuals (with 52 cases and 51 controls) agreed to participate in this study. Our study revealed a rare non-sense homozygous mutation NC_000002.11:g.2:26702224G>A; NM_001287489.2:c.2122C>T; NP_001274418.1:p.(Arg708∗) in the 18th exon of the OTOF gene. Our study provides the first insight into this homozygous condition, which has not been previously reported in ExAC, 1,000 Genome and genomAD databases. Furthermore, the variant was confirmed in the population cohort (n = 103) using Sanger sequencing. In addition to the pathogenic OTOF variant, the WES data also revealed novel and recurrent mutations in CDH23, GJB2, MYO15A, OTOG, and SLC26A4 genes. The rare pathogenic and the novel variants observed in this study have been submitted to the ClinVar database and are publicly available online with the accessions SCV001448680.1, SCV001448682.1 and SCV001448681.1. We conclude that OTOF-related NSHL hearing loss is prevalent in the region due to successive inbreeding in its generations. We recommend premarital genetic testing and genetic counseling strategies to minimize and control the disease risk in future generations.
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Affiliation(s)
- Mohd Fareed
- PK-PD Formulation and Toxicology Division, CSIR Indian Institute of Integrative Medicine, Jammu, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Varun Sharma
- Ancient DNA Laboratory, Birbal Sahni Institute of Palaeosciences, Lucknow, Uttar Pradesh, India
| | | | - Sayeed Ur Rehman
- Department of Biochemistry, School of Chemical and Life Sciences, Jamia Hamdard, New Delhi, India
| | - Gurdarshan Singh
- PK-PD Formulation and Toxicology Division, CSIR Indian Institute of Integrative Medicine, Jammu, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Mohammad Afzal
- Human Genetics and Toxicology Laboratory, Section of Genetics, Department of Zoology, Aligarh Muslim University, Aligarh, India
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Ahmed A, Wang M, Khan R, Shah AA, Guo H, Malik S, Xia K, Hu Z. A splice-site variant (c.3289-1G>T) in OTOF underlies profound hearing loss in a Pakistani kindred. BMC Med Genomics 2021; 14:2. [PMID: 33397372 PMCID: PMC7784026 DOI: 10.1186/s12920-020-00859-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2020] [Accepted: 12/14/2020] [Indexed: 12/02/2022] Open
Abstract
Background Hearing loss/deafness is a common otological disorder found in the Pakistani population due to the high prevalence of consanguineous unions, but the full range of genetic causes is still unknown. Methods A large consanguineous Pakistani kindred with hearing loss was studied. Whole-exome sequencing and Sanger sequencing were performed to search for the candidate gene underlying the disease phenotype. A minigene assay and reverse transcription polymerase chain reaction was used to assess the effect of splicing variants. Results The splicing variants of OTOF (NM_194248, c.3289-1G>T) cosegregated with the disease phenotype in this Pakistani family. The substitution of a single base pair causes the deletion of 10 bp (splicing variant 1) or 13 bp (splicing variant 2) from exon 27, which results in truncated proteins of 1141 and 1140 amino acids, respectively. Conclusion Our findings reveal an OTOF splice-site variant as pathogenic for profound hearing loss in this family.
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Affiliation(s)
- Ashfaque Ahmed
- Center for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China
| | - Meng Wang
- Center for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China
| | - Rizwan Khan
- Center for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China
| | - Abid Ali Shah
- Center for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China
| | - Hui Guo
- Center for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China
| | - Sajid Malik
- Human Genetics Program, Department of Zoology, Faculty of Biological Sciences, Quaid-I-Azam University, Islamabad, Pakistan.
| | - Kun Xia
- Center for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China.
| | - Zhengmao Hu
- Center for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China. .,Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China.
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Müller NIC, Sonntag M, Maraslioglu A, Hirtz JJ, Friauf E. Topographic map refinement and synaptic strengthening of a sound localization circuit require spontaneous peripheral activity. J Physiol 2019; 597:5469-5493. [PMID: 31529505 DOI: 10.1113/jp277757] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 09/13/2019] [Indexed: 12/21/2022] Open
Abstract
KEY POINTS Loss of the calcium sensor otoferlin disrupts neurotransmission from inner hair cells. Central auditory nuclei are functionally denervated in otoferlin knockout mice (Otof KOs) via gene ablation confined to the periphery. We employed juvenile and young adult Otof KO mice (postnatal days (P)10-12 and P27-49) as a model for lacking spontaneous activity and deafness, respectively. We studied the impact of peripheral activity on synaptic refinement in the sound localization circuit from the medial nucleus of the trapezoid body (MNTB) to the lateral superior olive (LSO). MNTB in vivo recordings demonstrated drastically reduced spontaneous spiking and deafness in Otof KOs. Juvenile KOs showed impaired synapse elimination and strengthening, manifested by broader MNTB-LSO inputs, imprecise MNTB-LSO topography and weaker MNTB-LSO fibres. The impairments persisted into young adulthood. Further functional refinement after hearing onset was undetected in young adult wild-types. Collectively, activity deprivation confined to peripheral protein loss impairs functional MNTB-LSO refinement during a critical prehearing period. ABSTRACT Circuit refinement is critical for the developing sound localization pathways in the auditory brainstem. In prehearing mice (hearing onset around postnatal day (P)12), spontaneous activity propagates from the periphery to central auditory nuclei. At the glycinergic projection from the medial nucleus of the trapezoid body (MNTB) to the lateral superior olive (LSO) of neonatal mice, super-numerous MNTB fibres innervate a given LSO neuron. Between P4 and P9, MNTB fibres are functionally eliminated, whereas the remaining fibres are strengthened. Little is known about MNTB-LSO circuit refinement after P20. Moreover, MNTB-LSO refinement upon activity deprivation confined to the periphery is largely unexplored. This leaves a considerable knowledge gap, as deprivation often occurs in patients with congenital deafness, e.g. upon mutations in the otoferlin gene (OTOF). Here, we analysed juvenile (P10-12) and young adult (P27-49) otoferlin knockout (Otof KO) mice with respect to MNTB-LSO refinement. MNTB in vivo recordings revealed drastically reduced spontaneous activity and deafness in knockouts (KOs), confirming deprivation. As RNA sequencing revealed Otof absence in the MNTB and LSO of wild-types, Otof loss in KOs is specific to the periphery. Functional denervation impaired MNTB-LSO synapse elimination and strengthening, which was assessed by glutamate uncaging and electrical stimulation. Impaired elimination led to imprecise MNTB-LSO topography. Impaired strengthening was associated with lower quantal content per MNTB fibre. In young adult KOs, the MNTB-LSO circuit remained unrefined. Further functional refinement after P12 appeared absent in wild-types. Collectively, we provide novel insights into functional MNTB-LSO circuit maturation governed by a cochlea-specific protein. The central malfunctions in Otof KOs may have implications for patients with sensorineuronal hearing loss.
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Affiliation(s)
- Nicolas I C Müller
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, D-67663, Kaiserslautern, Germany
| | - Mandy Sonntag
- Paul Flechsig Institute of Brain Research, Faculty of Medicine, University of Leipzig, D-04103, Leipzig, Germany
| | - Ayse Maraslioglu
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, D-67663, Kaiserslautern, Germany
| | - Jan J Hirtz
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, D-67663, Kaiserslautern, Germany.,Physiology of Neuronal Networks, Department of Biology, University of Kaiserslautern, D-67663, Kaiserslautern, Germany
| | - Eckhard Friauf
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, D-67663, Kaiserslautern, Germany
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Golbek TW, Padmanarayana M, Roeters SJ, Weidner T, Johnson CP, Baio JE. Otoferlin C2F Domain-Induced Changes in Membrane Structure Observed by Sum Frequency Generation. Biophys J 2019; 117:1820-1830. [PMID: 31587832 DOI: 10.1016/j.bpj.2019.09.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 08/16/2019] [Accepted: 09/10/2019] [Indexed: 12/30/2022] Open
Abstract
Proteins that contain C2 domains are involved in a variety of biological processes, including encoding of sound, cell signaling, and cell membrane repair. Of particular importance is the interface activity of the C-terminal C2F domain of otoferlin due to the pathological mutations known to significantly disrupt the protein's lipid membrane interface binding activity, resulting in hearing loss. Therefore, there is a critical need to define the geometry and positions of functionally important sites and structures at the otoferlin-lipid membrane interface. Here, we describe the first in situ probe of the protein orientation of otoferlin's C2F domain interacting with a cell membrane surface. To identify this protein's orientation at the lipid interface, we applied sum frequency generation (SFG) vibrational spectroscopy and coupled it with simulated SFG spectra to observe and quantify the otoferlin C2F domain interacting with model lipid membranes. A model cell membrane was built with equal amounts of phosphatidylserine and phosphatidylcholine. SFG measurements of the lipids that make up the model membrane indicate a 62% increase in amplitude from the SFG signal near 2075 cm-1 upon protein interaction, suggesting domain-induced changes in the orientation of the lipids and possible membrane curvature. This increase is related to lipid ordering caused by the docking interaction of the otoferlin C2F domain. SFG spectra taken from the amide-I region contain features near 1630 and 1670 cm-1 related to the C2F domains beta-sandwich secondary structure, thus indicating that the domain binds in a specific orientation. By mapping the simulated SFG spectra to the experimentally collected SFG spectra, we found the C2F domain of otoferlin orients 22° normal to the lipid surface. This information allows us to map what portion of the domain directly interacts with the lipid membrane.
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Affiliation(s)
- Thaddeus W Golbek
- School of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, Oregon; Department of Chemistry, Aarhus University, Aarhus, Denmark
| | | | | | - Tobias Weidner
- Department of Chemistry, Aarhus University, Aarhus, Denmark
| | - Colin P Johnson
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon.
| | - Joe E Baio
- School of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, Oregon.
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Peulen O, Rademaker G, Anania S, Turtoi A, Bellahcène A, Castronovo V. Ferlin Overview: From Membrane to Cancer Biology. Cells 2019; 8:cells8090954. [PMID: 31443490 PMCID: PMC6770723 DOI: 10.3390/cells8090954] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 08/20/2019] [Accepted: 08/21/2019] [Indexed: 02/06/2023] Open
Abstract
In mammal myocytes, endothelial cells and inner ear cells, ferlins are proteins involved in membrane processes such as fusion, recycling, endo- and exocytosis. They harbour several C2 domains allowing their interaction with phospholipids. The expression of several Ferlin genes was described as altered in several tumoural tissues. Intriguingly, beyond a simple alteration, myoferlin, otoferlin and Fer1L4 expressions were negatively correlated with patient survival in some cancer types. Therefore, it can be assumed that membrane biology is of extreme importance for cell survival and signalling, making Ferlin proteins core machinery indispensable for cancer cell adaptation to hostile environments. The evidences suggest that myoferlin, when overexpressed, enhances cancer cell proliferation, migration and metabolism by affecting various aspects of membrane biology. Targeting myoferlin using pharmacological compounds, gene transfer technology, or interfering RNA is now considered as an emerging therapeutic strategy.
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Affiliation(s)
- Olivier Peulen
- Metastasis Research Laboratory, Giga Cancer, University of Liège, B4000 Liège, Belgium.
| | - Gilles Rademaker
- Metastasis Research Laboratory, Giga Cancer, University of Liège, B4000 Liège, Belgium
| | - Sandy Anania
- Metastasis Research Laboratory, Giga Cancer, University of Liège, B4000 Liège, Belgium
| | - Andrei Turtoi
- Tumor Microenvironment Laboratory, Institut de Recherche en Cancérologie de Montpellier, INSERM U1194, 34000 Montpellier, France
- Institut du Cancer de Montpeiller, 34000 Montpellier, France
- Université de Montpellier, 34000 Montpellier, France
| | - Akeila Bellahcène
- Metastasis Research Laboratory, Giga Cancer, University of Liège, B4000 Liège, Belgium
| | - Vincent Castronovo
- Metastasis Research Laboratory, Giga Cancer, University of Liège, B4000 Liège, Belgium
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Fischer AU, Müller NIC, Deller T, Del Turco D, Fisch JO, Griesemer D, Kattler K, Maraslioglu A, Roemer V, Xu-Friedman MA, Walter J, Friauf E. GABA is a modulator, rather than a classical transmitter, in the medial nucleus of the trapezoid body-lateral superior olive sound localization circuit. J Physiol 2019; 597:2269-2295. [PMID: 30776090 DOI: 10.1113/jp277566] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 02/18/2019] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS The lateral superior olive (LSO), a brainstem hub involved in sound localization, integrates excitatory and inhibitory inputs from the ipsilateral and the contralateral ear, respectively. In gerbils and rats, inhibition to the LSO reportedly shifts from GABAergic to glycinergic within the first three postnatal weeks. Surprisingly, we found no evidence for synaptic GABA signalling during this time window in mouse LSO principal neurons. However, we found that presynaptic GABAB Rs modulate Ca2+ influx into medial nucleus of the trapezoid body axon terminals, resulting in reduced synaptic strength. Moreover, GABA elicited strong responses in LSO neurons that were mediated by extrasynaptic GABAA Rs. RNA sequencing revealed highly abundant δ subunits, which are characteristic of extrasynaptic receptors. Whereas GABA increased the excitability of neonatal LSO neurons, it reduced the excitability around hearing onset. Collectively, GABA appears to control the excitability of mouse LSO neurons via extrasynaptic and presynaptic signalling. Thus, GABA acts as a modulator, rather than as a classical transmitter. ABSTRACT GABA and glycine mediate fast inhibitory neurotransmission and are coreleased at several synapse types. Here we assessed the contribution of GABA and glycine in synaptic transmission between the medial nucleus of the trapezoid body (MNTB) and the lateral superior olive (LSO), two nuclei involved in sound localization. Whole-cell patch-clamp experiments in acute mouse brainstem slices at postnatal days (P) 4 and 11 during pharmacological blockade of GABAA receptors (GABAA Rs) and/or glycine receptors demonstrated no GABAergic synaptic component on LSO principal neurons. A GABAergic component was absent in evoked inhibitory postsynaptic currents and miniature events. Coimmunofluorescence experiments revealed no codistribution of the presynaptic GABAergic marker GAD65/67 with gephyrin, a postsynaptic marker for GABAA Rs, corroborating the conclusion that GABA does not act synaptically in the mouse LSO. Imaging experiments revealed reduced Ca2+ influx into MNTB axon terminals following activation of presynaptic GABAB Rs. GABAB R activation reduced the synaptic strength at P4 and P11. GABA appears to act on extrasynaptic GABAA Rs as demonstrated by application of 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol, a δ-subunit-specific GABAA R agonist. RNA sequencing showed high mRNA levels for the δ-subunit in the LSO. Moreover, GABA transporters GAT-1 and GAT-3 appear to control extracellular GABA. Finally, we show an age-dependent effect of GABA on the excitability of LSO neurons. Whereas tonic GABA increased the excitability at P4, leading to spike facilitation, it decreased the excitability at P11 via shunting inhibition through extrasynaptic GABAA Rs. Taken together, we demonstrate a modulatory role of GABA in the murine LSO, rather than a function as a classical synaptic transmitter.
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Affiliation(s)
- Alexander U Fischer
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, D-67663, Kaiserslautern, Germany
| | - Nicolas I C Müller
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, D-67663, Kaiserslautern, Germany
| | - Thomas Deller
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University Frankfurt, Theodor-Stern-Kai 7, D-60590, Frankfurt am Main, Germany
| | - Domenico Del Turco
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University Frankfurt, Theodor-Stern-Kai 7, D-60590, Frankfurt am Main, Germany
| | - Jonas O Fisch
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, D-67663, Kaiserslautern, Germany
| | - Désirée Griesemer
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, D-67663, Kaiserslautern, Germany
| | - Kathrin Kattler
- Genetics/Epigenetic Group, Department of Biological Sciences, Saarland University, D-66123, Saarbrücken
| | - Ayse Maraslioglu
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, D-67663, Kaiserslautern, Germany
| | - Vera Roemer
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, D-67663, Kaiserslautern, Germany
| | - Matthew A Xu-Friedman
- Department of Biological Sciences, University at Buffalo, State University of New York, Buffalo, NY, 14260, USA
| | - Jörn Walter
- Genetics/Epigenetic Group, Department of Biological Sciences, Saarland University, D-66123, Saarbrücken
| | - Eckhard Friauf
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, D-67663, Kaiserslautern, Germany
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12
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Viral Transfer of Mini-Otoferlins Partially Restores the Fast Component of Exocytosis and Uncovers Ultrafast Endocytosis in Auditory Hair Cells of Otoferlin Knock-Out Mice. J Neurosci 2019; 39:3394-3411. [PMID: 30833506 DOI: 10.1523/jneurosci.1550-18.2018] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 10/24/2018] [Accepted: 11/02/2018] [Indexed: 01/06/2023] Open
Abstract
Transmitter release at auditory inner hair cell (IHC) ribbon synapses involves exocytosis of glutamatergic vesicles during voltage activation of L-type Cav1.3 calcium channels. At these synapses, the fast and indefatigable release of synaptic vesicles by IHCs is controlled by otoferlin, a six-C2-domain (C2-ABCDEF) protein that functions as a high-affinity Ca2+ sensor. The molecular events by which each otoferlin C2 domain contributes to the regulation of the synaptic vesicle cycle in IHCs are still incompletely understood. Here, we investigate their role using a cochlear viral cDNA transfer approach in vivo, where IHCs of mouse lacking otoferlin (Otof -/- mice of both sexes) were virally transduced with cDNAs of various mini-otoferlins. Using patch-clamp recordings and membrane capacitance measurements, we show that the viral transfer of mini-otoferlin containing C2-ACEF, C2-EF, or C2-DEF partially restores the fast exocytotic component in Otof -/- mouse IHCs. The restoration was much less efficient with C2-ACDF, underlining the importance of the C2-EF domain. None of the mini-otoferlins tested restored the sustained component of vesicle release, explaining the absence of hearing recovery. The restoration of the fast exocytotic component in the transduced Otof -/- IHCs was also associated with a recovery of Ca2+ currents with normal amplitude and fast time inactivation, confirming that the C-terminal C2 domains of otoferlin are essential for normal gating of Cav1.3 channels. Finally, the reintroduction of the mini-otoferlins C2-EF, C2-DEF, or C2-ACEF allowed us to uncover and characterize for the first time a dynamin-dependent ultrafast endocytosis in IHCs.SIGNIFICANCE STATEMENT Otoferlin, a large six-C2-domain protein, is essential for synaptic vesicle exocytosis at auditory hair cell ribbon synapses. Here, we show that the viral expression of truncated forms of otoferlin (C2-EF, C2-DEF, and C2-ACEF) can partially rescue the fast and transient release component of exocytosis in mouse hair cells lacking otoferlin, yet cannot sustain exocytosis after long repeated stimulation. Remarkably, these hair cells also display a dynamin-dependent ultrafast endocytosis. Overall, our study uncovers the pleiotropic role of otoferlin in the hair cell synaptic vesicle cycle, notably in triggering both ultrafast exocytosis and endocytosis and recruiting synaptic vesicles to the active zone.
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13
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Bonventre JA, Holman C, Manchanda A, Codding SJ, Chau T, Huegel J, Barton C, Tanguay R, Johnson CP. Fer1l6 is essential for the development of vertebrate muscle tissue in zebrafish. Mol Biol Cell 2018; 30:293-301. [PMID: 30516436 PMCID: PMC6589578 DOI: 10.1091/mbc.e18-06-0401] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The precise spatial and temporal expression of genes is essential for proper organismal development. Despite their importance, however, many developmental genes have yet to be identified. We have determined that Fer1l6, a member of the ferlin family of genes, is a novel factor in zebrafish development. We find that Fer1l6 is expressed broadly in the trunk and head of zebrafish larvae and is more restricted to gills and female gonads in adult zebrafish. Using both genetic mutant and morpholino knockdown models, we found that loss of Fer1l6 led to deformation of striated muscle tissues, delayed development of the heart, and high morbidity. Further, expression of genes associated with muscle cell proliferation and differentiation were affected. Fer1l6 was also detected in the C2C12 cell line, and unlike other ferlin homologues, we found Fer1l6 expression was independent of the myoblast-to-myotube transition. Finally, analysis of cell and recombinant protein-based assays indicate that Fer1l6 colocalizes with syntaxin 4 and vinculin, and that the putative C2 domains interact with lipid membranes. We conclude that Fer1l6 has diverged from other vertebrate ferlins to play an essential role in zebrafish skeletal and cardiac muscle development.
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Affiliation(s)
- Josephine A Bonventre
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331
| | - Chelsea Holman
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331
| | - Aayushi Manchanda
- Molecular and Cellular Biology Program, Oregon State University, Corvallis, OR 97331
| | - Sara J Codding
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331
| | - Trisha Chau
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331
| | - Jacob Huegel
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331
| | - Carrie Barton
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR 97331
| | - Robert Tanguay
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR 97331
| | - Colin P Johnson
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331.,Molecular and Cellular Biology Program, Oregon State University, Corvallis, OR 97331
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14
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Pangrsic T, Vogl C. Balancing presynaptic release and endocytic membrane retrieval at hair cell ribbon synapses. FEBS Lett 2018; 592:3633-3650. [PMID: 30251250 DOI: 10.1002/1873-3468.13258] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 09/18/2018] [Accepted: 09/19/2018] [Indexed: 11/07/2022]
Abstract
The timely and reliable processing of auditory and vestibular information within the inner ear requires highly sophisticated sensory transduction pathways. On a cellular level, these demands are met by hair cells, which respond to sound waves - or alterations in body positioning - by releasing glutamate-filled synaptic vesicles (SVs) from their presynaptic active zones with unprecedented speed and exquisite temporal fidelity, thereby initiating the auditory and vestibular pathways. In order to achieve this, hair cells have developed anatomical and molecular specializations, such as the characteristic and name-giving 'synaptic ribbons' - presynaptically anchored dense bodies that tether SVs prior to release - as well as other unique or unconventional synaptic proteins. The tightly orchestrated interplay between these molecular components enables not only ultrafast exocytosis, but similarly rapid and efficient compensatory endocytosis. So far, the knowledge of how endocytosis operates at hair cell ribbon synapses is limited. In this Review, we summarize recent advances in our understanding of the SV cycle and molecular anatomy of hair cell ribbon synapses, with a focus on cochlear inner hair cells.
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Affiliation(s)
- Tina Pangrsic
- Synaptic Physiology of Mammalian Vestibular Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine, University Medical Center Göttingen, Germany
| | - Christian Vogl
- Presynaptogenesis and Intracellular Transport in Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine, University Medical Center Göttingen, Germany
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15
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Johnson CP. Emerging Functional Differences between the Synaptotagmin and Ferlin Calcium Sensor Families. Biochemistry 2017; 56:6413-6417. [PMID: 29110470 PMCID: PMC5730944 DOI: 10.1021/acs.biochem.7b00928] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
The ferlin family
proteins have emerged as multi-C2 domain regulators
of calcium-triggered membrane fusion and fission events. While initially
determined to share many of the features of members of the synaptotagmin
family of calcium sensors, ferlins in more recent studies have been
found to interact directly with non-neuronal voltage-gated calcium
channels and nucleate the assembly of membrane-trafficking protein
complexes, functions that distinguish them from the more well studied
members of the synaptotagmin family. Here we highlight some of the
recent findings that have advanced our understanding of ferlins and
their functional differences with the synaptotagmin family.
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Affiliation(s)
- Colin P Johnson
- Department of Biochemistry and Biophysics, Oregon State University , Corvallis, Oregon 97331-4003, United States
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16
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Meese S, Cepeda AP, Gahlen F, Adams CM, Ficner R, Ricci AJ, Heller S, Reisinger E, Herget M. Activity-Dependent Phosphorylation by CaMKIIδ Alters the Ca 2+ Affinity of the Multi-C 2-Domain Protein Otoferlin. Front Synaptic Neurosci 2017; 9:13. [PMID: 29046633 PMCID: PMC5632675 DOI: 10.3389/fnsyn.2017.00013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 09/11/2017] [Indexed: 01/20/2023] Open
Abstract
Otoferlin is essential for fast Ca2+-triggered transmitter release from auditory inner hair cells (IHCs), playing key roles in synaptic vesicle release, replenishment and retrieval. Dysfunction of otoferlin results in profound prelingual deafness. Despite its crucial role in cochlear synaptic processes, mechanisms regulating otoferlin activity have not been studied to date. Here, we identified Ca2+/calmodulin-dependent serine/threonine kinase II delta (CaMKIIδ) as an otoferlin binding partner by pull-downs from chicken utricles and reassured interaction by a co-immunoprecipitation with heterologously expressed proteins in HEK cells. We confirmed the expression of CaMKIIδ in rodent IHCs by immunohistochemistry and real-time PCR. A proximity ligation assay indicates close proximity of the two proteins in rat IHCs, suggesting that otoferlin and CaMKIIδ also interact in mammalian IHCs. In vitro phosphorylation of otoferlin by CaMKIIδ revealed ten phosphorylation sites, five of which are located within C2-domains. Exchange of serines/threonines at phosphorylated sites into phosphomimetic aspartates reduces the Ca2+ affinity of the recombinant C2F domain 10-fold, and increases the Ca2+ affinity of the C2C domain. Concordantly, we show that phosphorylation of otoferlin and/or its interaction partners are enhanced upon hair cell depolarization and blocked by pharmacological CaMKII inhibition. We therefore propose that otoferlin activity is regulated by CaMKIIδ in IHCs.
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Affiliation(s)
- Sandra Meese
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, and Collaborative Research Center 889, University of Göttingen, Göttingen, Germany.,Göttingen Graduate School for Neurosciences, Biophysics, and Molecular Biosciences, Göttingen, Germany
| | - Andreia P Cepeda
- Göttingen Graduate School for Neurosciences, Biophysics, and Molecular Biosciences, Göttingen, Germany.,Molecular Biology of Cochlear Neurotransmission Group, Department of Otorhinolaryngology, University Medical Center Göttingen, and Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
| | - Felix Gahlen
- Department of Otorhinolaryngology, Head and Neck Surgery, Ruhr-University Bochum, Bochum, Germany
| | - Christopher M Adams
- Stanford University Mass Spectrometry, Stanford University, Stanford, CA, United States
| | - Ralf Ficner
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, and Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
| | - Anthony J Ricci
- Department of Otolaryngology, Head and Neck Surgery, Stanford School of Medicine, Stanford, CA, United States
| | - Stefan Heller
- Department of Otolaryngology, Head and Neck Surgery, Stanford School of Medicine, Stanford, CA, United States
| | - Ellen Reisinger
- Molecular Biology of Cochlear Neurotransmission Group, Department of Otorhinolaryngology, University Medical Center Göttingen, and Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
| | - Meike Herget
- Department of Otolaryngology, Head and Neck Surgery, Stanford School of Medicine, Stanford, CA, United States
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17
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Drescher DG, Selvakumar D, Drescher MJ. Analysis of Protein Interactions by Surface Plasmon Resonance. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2017; 110:1-30. [PMID: 29412994 DOI: 10.1016/bs.apcsb.2017.07.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Surface plasmon resonance is an optical technique that is utilized for detecting molecular interactions, such as interactions that occur between proteins or other classes of molecules. Binding of a mobile molecule (analyte) to a molecule immobilized on a thin metal film (ligand) changes the refractive index of the film. The angle of extinction of light that is completely reflected after polarized light impinges upon the film, is altered and monitored as a change in detector position for a dip in reflected intensity (the surface plasmon resonance phenomenon). Because the method strictly detects mass, there is no need to label the interacting components, thus eliminating possible changes of their molecular properties. In this chapter, we review essential SPR methodology and present applications to basic science and human disease.
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Affiliation(s)
- Dennis G Drescher
- Wayne State University School of Medicine, Detroit, MI, United States.
| | | | - Marian J Drescher
- Wayne State University School of Medicine, Detroit, MI, United States
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18
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Al-Wardy NM, Al-Kindi MN, Al-Khabouri MJ, Tamimi Y, Van Camp G. A novel missense mutation in the C2C domain of otoferlin causes profound hearing impairment in an Omani family with auditory neuropathy. Saudi Med J 2017; 37:1068-75. [PMID: 27652356 PMCID: PMC5075369 DOI: 10.15537/smj.2016.10.14967] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
OBJECTIVES To identify genetic defects in an Omani family diagnosed with deafness. METHODS A cross-sectional association study was conducted at the Department of Biochemistry, College of Medicine and Health Sciences, Sultan Qaboos University, Al-Khoud, Oman and the Centre of Medical Genetics, University of Antwerp, Antwerp, Belgium between August 2010 and September 2014. Microsatellites markers for nine non-syndromic genes were used to genotype the defective locus using the extracted DNA from family members. Sanger sequencing method was used to identify the disease causative mutation. Eazy linkage 5.05 was used to calculate the logarithm of odds score. Lasergene suite was used to detect the mutation position, and Phyre2, SMART, Rasmol, and GOR IV were used to predict the effects of the defect on protein structure and function. RESULTS The disease was linked to markers located on chromosome-2 and covering the OTOF (DFNB9) gene. A novel missense mutation that changed nucleotide C to G at position c.1469 and consequently the amino acid Proline to Arginine (P490R) on exon 15 was detected. Protein modeling analysis revealed the impact of the mutation on protein structure and the relevant C2C domain. The mutation seems to create a new protein isoform homologous to the complement component C1q. CONCLUSION These findings suggest that the mutation found in C2C domain of the OTOF gene is likely to cause deafness in the studied family reflecting the importance of C2 domains of otoferlin in hearing loss.
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Affiliation(s)
- Nadia M Al-Wardy
- Department of Biochemistry, College of Medicine & Health Sciences, Sultan Qaboos University, Al-Khoud, Oman. E-mail.
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19
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Selvakumar D, Drescher MJ, Deckard NA, Ramakrishnan NA, Morley BJ, Drescher DG. Dopamine D1A directly interacts with otoferlin synaptic pathway proteins: Ca2+ and phosphorylation underlie an NSF-to-AP2mu1 molecular switch. Biochem J 2017; 474:79-104. [PMID: 27821621 PMCID: PMC6310132 DOI: 10.1042/bcj20160690] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 10/15/2016] [Accepted: 11/07/2016] [Indexed: 11/17/2022]
Abstract
Dopamine receptors regulate exocytosis via protein-protein interactions (PPIs) as well as via adenylyl cyclase transduction pathways. Evidence has been obtained for PPIs in inner ear hair cells coupling D1A to soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein receptor (SNARE)-related proteins snapin, otoferlin, N-ethylmaleimide-sensitive factor (NSF), and adaptor-related protein complex 2, mu 1 (AP2mu1), dependent on [Ca2+] and phosphorylation. Specifically, the carboxy terminus of dopamine D1A was found to directly bind t-SNARE-associated protein snapin in teleost and mammalian hair cell models by yeast two-hybrid (Y2H) and pull-down assays, and snapin directly interacts with hair cell calcium-sensor otoferlin. Surface plasmon resonance (SPR) analysis, competitive pull-downs, and co-immunoprecipitation indicated that these interactions were promoted by Ca2+ and occur together. D1A was also found to separately interact with NSF, but with an inverse dependence on Ca2+ Evidence was obtained, for the first time, that otoferlin domains C2A, C2B, C2D, and C2F interact with NSF and AP2mu1, whereas C2C or C2E do not bind to either protein, representing binding characteristics consistent with respective inclusion or omission in individual C2 domains of the tyrosine motif YXXΦ. In competitive pull-down assays, as predicted by KD values from SPR (+Ca2+), C2F pulled down primarily NSF as opposed to AP2mu1. Phosphorylation of AP2mu1 gave rise to a reversal: an increase in binding by C2F to phosphorylated AP2mu1 was accompanied by a decrease in binding to NSF, consistent with a molecular switch for otoferlin from membrane fusion (NSF) to endocytosis (AP2mu1). An increase in phosphorylated AP2mu1 at the base of the cochlear inner hair cell was the observed response elicited by a dopamine D1A agonist, as predicted.
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Affiliation(s)
- Dakshnamurthy Selvakumar
- Laboratory of Bio-otology, Department of Otolaryngology, Wayne State University School of Medicine, Detroit, MI 48201, U.S.A
| | - Marian J Drescher
- Laboratory of Bio-otology, Department of Otolaryngology, Wayne State University School of Medicine, Detroit, MI 48201, U.S.A.
| | - Nathan A Deckard
- Laboratory of Bio-otology, Department of Otolaryngology, Wayne State University School of Medicine, Detroit, MI 48201, U.S.A
| | - Neeliyath A Ramakrishnan
- Laboratory of Bio-otology, Department of Otolaryngology, Wayne State University School of Medicine, Detroit, MI 48201, U.S.A
| | - Barbara J Morley
- Boys Town National Research Hospital, Omaha, Nebraska 68131, U.S.A
| | - Dennis G Drescher
- Laboratory of Bio-otology, Department of Otolaryngology, Wayne State University School of Medicine, Detroit, MI 48201, U.S.A
- Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI 48201, U.S.A
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20
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Morley BJ, Lysakowski A, Vijayakumar S, Menapace D, Jones TA. Nicotinic acetylcholine receptors regulate vestibular afferent gain and activation timing. J Comp Neurol 2016; 525:1216-1233. [PMID: 27718229 DOI: 10.1002/cne.24131] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 09/28/2016] [Accepted: 10/01/2016] [Indexed: 01/02/2023]
Abstract
Little is known about the function of the cholinergic efferents innervating peripheral vestibular hair cells. We measured vestibular sensory evoked potentials (VsEPs) in α9 knockout (KO) mice, α10 KO mice, α7 KO mice, α9/10 and α7/9 double KO mice, and wild-type (WT) controls. We also studied the morphology and ultrastructure of efferent terminals on vestibular hair cells in α9, α10, and α9/10 KOs. Both type I and type ll vestibular hair cells express the α9 and α10 subunits. The efferent boutons on vestibular cells in α9, α10, and α9/10 KOs appeared normal, but a quantitative analysis was not performed. Mean VsEP thresholds were significantly elevated in α9 and α9/10 KO animals. Some α9 and α9/10 KO animals, however, had normal or near-normal thresholds, whereas others were greatly affected. Despite individual variability in threshold responses, latencies were consistently shortened. The double α7/9 KO resulted in decreased variance by normalizing waveforms and latencies. The phenotypes of the α7 and α10 single KOs were identical. Both α7 and α10 KO mice evidenced normal thresholds, decreased activation latencies, and larger amplitudes compared with WT mice. The data suggest a complex interaction of nicotinic acetylcholine receptors (nAChRs) in regulating vestibular afferent gain and activation timing. Although the α9/10 heteromeric nAChR is an important component of vestibular efferent activity, other peripheral or central nAChRs involving the α7 subunit or α10 subunit and α9 homomeric receptors are also important. J. Comp. Neurol. 525:1216-1233, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
| | - Anna Lysakowski
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, Illinois, 60612
| | - Sarath Vijayakumar
- Department of Special Education and Communication Disorders, University of Nebraska, Lincoln, Nebraska, 68583
| | - Deanna Menapace
- Boys Town National Research Hospital, Omaha, Nebraska, 68131
| | - Timothy A Jones
- Department of Special Education and Communication Disorders, University of Nebraska, Lincoln, Nebraska, 68583
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21
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Swanson CJ, Sommese RF, Petersen KJ, Ritt M, Karslake J, Thomas DD, Sivaramakrishnan S. Calcium Stimulates Self-Assembly of Protein Kinase C α In Vitro. PLoS One 2016; 11:e0162331. [PMID: 27706148 PMCID: PMC5051681 DOI: 10.1371/journal.pone.0162331] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 08/22/2016] [Indexed: 11/18/2022] Open
Abstract
Protein kinase C α (PKCα) is a nodal regulator in several intracellular signaling networks. PKCα is composed of modular domains that interact with each other to dynamically regulate spatial-temporal function. We find that PKCα specifically, rapidly and reversibly self-assembles in the presence of calcium in vitro. This phenomenon is dependent on, and can be modulated by an intramolecular interaction between the C1a and C2 protein domains of PKCα. Next, we monitor self-assembly of PKC—mCitrine fusion proteins using time-resolved and steady-state homoFRET. HomoFRET between full-length PKCα molecules is observed when in solution with both calcium and liposomes containing either diacylglycerol (DAG) or phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). Surprisingly, the C2 domain is sufficient to cluster on liposomes containing PI(4,5)P2, indicating the C1a domain is not required for self-assembly in this context. We conclude that three distinct clustered states of PKCα can be formed depending on what combination of cofactors are bound, but Ca2+ is minimally required and sufficient for clustering.
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Affiliation(s)
- Carter J. Swanson
- Biophysics Program, University of Michigan, Ann Arbor, 48109, United States of America
| | - Ruth F. Sommese
- Dept. of Genetics, Cell Biology and Development, University of Minnesota, Twin Cities, 55455, United States of America
| | - Karl J. Petersen
- Dept. of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Twin Cities, 55455, United States of America
| | - Michael Ritt
- Dept. of Genetics, Cell Biology and Development, University of Minnesota, Twin Cities, 55455, United States of America
| | - Joshua Karslake
- Biophysics Program, University of Michigan, Ann Arbor, 48109, United States of America
| | - David D. Thomas
- Dept. of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Twin Cities, 55455, United States of America
| | - Sivaraj Sivaramakrishnan
- Dept. of Genetics, Cell Biology and Development, University of Minnesota, Twin Cities, 55455, United States of America
- * E-mail:
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22
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Drescher DG, Dakshnamurthy S, Drescher MJ, Ramakrishnan NA. Surface Plasmon Resonance (SPR) Analysis of Binding Interactions of Inner-Ear Proteins. Methods Mol Biol 2016; 1427:165-187. [PMID: 27259927 DOI: 10.1007/978-1-4939-3615-1_10] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Surface plasmon resonance is an optical technique that is utilized for detecting molecular interactions. Binding of a mobile molecule (analyte) to a molecule immobilized on a thin metal film (ligand) changes the refractive index of the film. The angle of extinction of light that is completely reflected after polarized light impinges upon the film, is altered, and monitored as a change in detector position for a dip in reflected intensity (the surface plasmon resonance phenomenon). Because the method strictly detects mass, there is no need to label the interacting components, thus eliminating possible changes of their molecular properties. We have utilized surface plasmon resonance to study interaction of proteins of inner-ear sensory epithelia.
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Affiliation(s)
- Dennis G Drescher
- Departments of Otolaryngology and Biochemistry-Molecular Biology, Wayne State University School of Medicine, 540 East Canfield Avenue, Detroit, MI, 48201, USA.
| | - Selvakumar Dakshnamurthy
- Department of Otolaryngology, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Marian J Drescher
- Department of Otolaryngology, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Neeliyath A Ramakrishnan
- Department of Otolaryngology, Wayne State University School of Medicine, Detroit, MI, 48201, USA
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23
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Plasma membrane and cytoskeleton dynamics during single-cell wound healing. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015. [DOI: 10.1016/j.bbamcr.2015.07.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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24
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Wichmann C, Moser T. Relating structure and function of inner hair cell ribbon synapses. Cell Tissue Res 2015; 361:95-114. [PMID: 25874597 PMCID: PMC4487357 DOI: 10.1007/s00441-014-2102-7] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 12/18/2014] [Indexed: 01/28/2023]
Abstract
In the mammalian cochlea, sound is encoded at synapses between inner hair cells (IHCs) and type I spiral ganglion neurons (SGNs). Each SGN receives input from a single IHC ribbon-type active zone (AZ) and yet SGNs indefatigably spike up to hundreds of Hz to encode acoustic stimuli with submillisecond precision. Accumulating evidence indicates a highly specialized molecular composition and structure of the presynapse, adapted to suit these high functional demands. However, we are only beginning to understand key features such as stimulus-secretion coupling, exocytosis mechanisms, exo-endocytosis coupling, modes of endocytosis and vesicle reformation, as well as replenishment of the readily releasable pool. Relating structure and function has become an important avenue in addressing these points and has been applied to normal and genetically manipulated hair cell synapses. Here, we review some of the exciting new insights gained from recent studies of the molecular anatomy and physiology of IHC ribbon synapses.
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Affiliation(s)
- C. Wichmann
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University Medical Center Göttingen, Göttingen, Germany
| | - T. Moser
- Collaborative Research Center 889, University Medical Center Göttingen, Göttingen, Germany
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, Göttingen, Germany
- Bernstein Center for Computational Neuroscience, University of Göttingen, Göttingen, Germany
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25
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Otoferlin deficiency in zebrafish results in defects in balance and hearing: rescue of the balance and hearing phenotype with full-length and truncated forms of mouse otoferlin. Mol Cell Biol 2015; 35:1043-54. [PMID: 25582200 DOI: 10.1128/mcb.01439-14] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Sensory hair cells convert mechanical motion into chemical signals. Otoferlin, a six-C2 domain transmembrane protein linked to deafness in humans, is hypothesized to play a role in exocytosis at hair cell ribbon synapses. To date, however, otoferlin has been studied almost exclusively in mouse models, and no rescue experiments have been reported. Here we describe the phenotype associated with morpholino-induced otoferlin knockdown in zebrafish and report the results of rescue experiments conducted with full-length and truncated forms of otoferlin. We found that expression of otoferlin occurs early in development and is restricted to hair cells and the midbrain. Immunofluorescence microscopy revealed localization to both apical and basolateral regions of hair cells. Knockdown of otoferlin resulted in hearing and balance defects, as well as locomotion deficiencies. Further, otoferlin morphants had uninflated swim bladders. Rescue experiments conducted with mouse otoferlin restored hearing, balance, and inflation of the swim bladder. Remarkably, truncated forms of otoferlin retaining the C-terminal C2F domain also rescued the otoferlin knockdown phenotype, while the individual N-terminal C2A domain did not. We conclude that otoferlin plays an evolutionarily conserved role in vertebrate hearing and that truncated forms of otoferlin can rescue hearing and balance.
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26
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Padmanarayana M, Hams N, Speight LC, Petersson EJ, Mehl RA, Johnson CP. Characterization of the lipid binding properties of Otoferlin reveals specific interactions between PI(4,5)P2 and the C2C and C2F domains. Biochemistry 2014; 53:5023-33. [PMID: 24999532 PMCID: PMC4144714 DOI: 10.1021/bi5004469] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
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Otoferlin
is a transmembrane protein consisting of six C2 domains,
proposed to act as a calcium sensor for exocytosis. Although otoferlin
is believed to bind calcium and lipids, the lipid specificity and
identity of the calcium binding domains are controversial. Further,
it is currently unclear whether the calcium binding affinity of otoferlin
quantitatively matches the maximal intracellular presynaptic calcium
concentrations of ∼30–50 μM known to elicit exocytosis.
To characterize the calcium and lipid binding properties of otoferlin,
we used isothermal titration calorimetry (ITC), liposome sedimentation
assays, and fluorescence spectroscopy. Analysis of ITC data indicates
that with the exception of the C2A domain, the C2 domains of otoferlin
bind multiple calcium ions with moderate (Kd = 25–95 μM) and low affinities (Kd = 400–700 μM) in solution. However, in the presence
of liposomes, the calcium sensitivity of the domains increased by
up to 10-fold. It was also determined that calcium enhanced liposome
binding for domains C2B–C2E, whereas the C2F domain bound liposomes
in a calcium-independent manner. Mutations that abrogate calcium binding
in C2F do not disrupt liposome binding, supporting the conclusion
that the interaction of the C2F domain with phosphatidylserine is
calcium-independent. Further, domains C2C and C2F, not domains C2A,
C2B, C2D, and C2E, bound phosphatidylinositol 4,5-bisphosphate 1,2-dioleoyl-sn-glycero-3-phospho(1′-myoinositol-4′,5′-bisphosphate) [PI(4,5)P2], which preferentially
steered them toward liposomes harboring PI(4,5)P2. Remarkably, lysine
mutations L478A and L480A in C2C selectively weaken the PI(4,5)P2
interaction while leaving phosphatidylserine binding unaffected. Finally,
shifts in the emission spectra of an environmentally sensitive fluorescent
unnatural amino acid indicate that the calcium binding loops of the
C2F domain directly interact with the lipid bilayer of negatively
charged liposomes in a calcium-independent manner. On the basis of
these results, we propose that the C2F and C2C domains of otoferlin
preferentially bind PI(4,5)P2 and that PI(4,5)P2 may serve to target
otoferlin to the presynapse in a calcium-independent manner. This
positioning would facilitate fast calcium-dependent exocytosis at
the hair cell synapse.
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Affiliation(s)
- Murugesh Padmanarayana
- Department of Biochemistry and Biophysics, Oregon State University , Corvallis, Oregon 973331, United States
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