1
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Sekulic-Jablanovic M, Paproth J, Sgambato C, Albano G, Fuster DG, Bodmer D, Petkovic V. Lack of NHE6 and Inhibition of NKCC1 Associated With Increased Permeability in Blood Labyrinth Barrier-Derived Endothelial Cell Layer. Front Cell Neurosci 2022; 16:862119. [PMID: 35496913 PMCID: PMC9039518 DOI: 10.3389/fncel.2022.862119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 03/17/2022] [Indexed: 12/20/2022] Open
Abstract
Acoustic trauma, autoimmune inner ear disease, and presbycusis feature loss of the integrity of the blood-labyrinth barrier (BLB). Normal BLB function depends on endothelial structural integrity, which is supported and maintained by tight junctions and adherens junctions within the microvascular endothelial layer. When these junctions are disrupted, vascular leakage occurs. Tight junctions and adherens junctions are functionally and structurally linked, but the exact signaling pathways underlying their interaction remain unknown. In addition, solute carriers (SC) are essential for optimal exchange through BLB. Previously, we found that SC family member, the sodium–hydrogen exchanger NHE6, was expressed in all wildtype cochlear tissues, and that Nhe6-knockout mice displayed moderate hearing loss. Moreover, NHE6 depletion affected Trk protein turnover and endosomal signaling. Here, we investigated whether NHE6 might impact BLB integrity. We found that Nhe6-knockout, BLB-derived endothelial cells showed reduced expression of major junctional genes: Tjp1, F11r, Ocln, Cdh5, and Cldn5. Co-culturing BLB-derived endothelial cells with pericytes and/or perivascular resident macrophage-like melanocytes in a transwell system showed that monolayers of Nhe6-knockout BLB-derived cells had lower electrical resistance and higher permeability, compared to wildtype endothelial monolayers. Additionally, another SC, NKCC1, which was previously linked to congenital deafness, was downregulated in our Nhe6-knockout mouse model. Blocking NKCC1 with a NKCC1-specific inhibitor, bumetanide, in wildtype BLB-derived endothelial cells also caused the downregulation of major junctional proteins, particularly Tjp1 and F11r, which encode the zonula occludens and junctional adhesion molecule-1 proteins, respectively. Moreover, bumetanide treatment increased cell permeability. In conclusion, we showed that the lack or inhibition of NHE6 or NKCC1 affected the permeability of endothelial BLB-derived cells. These findings suggested that NHE6 and NKCC1 could serve as potential targets for modifying BLB permeability to facilitate drug delivery across the BLB to the cochlea or to protect the cochlea from ototoxic insults.
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Affiliation(s)
- Marijana Sekulic-Jablanovic
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
- *Correspondence: Marijana Sekulic-Jablanovic,
| | - Jessica Paproth
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
| | - Cinzia Sgambato
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
| | - Giuseppe Albano
- Inselspital Bern, Department of Biomedical Research, University of Bern, Bern, Switzerland
| | - Daniel G. Fuster
- Inselspital Bern, Department of Biomedical Research, University of Bern, Bern, Switzerland
| | - Daniel Bodmer
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
- Clinic for Otolaryngology, Head and Neck Surgery, University Hospital Basel, Basel, Switzerland
| | - Vesna Petkovic
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
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2
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Sekulic-Jablanovic M, Wright MB, Petkovic V, Bodmer D. Pioglitazone Ameliorates Gentamicin Ototoxicity by Affecting the TLR and STAT Pathways in the Early Postnatal Organ of Corti. Front Cell Neurosci 2020; 14:566148. [PMID: 33192313 PMCID: PMC7658481 DOI: 10.3389/fncel.2020.566148] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 09/25/2020] [Indexed: 12/20/2022] Open
Abstract
Noise trauma, infection, and ototoxic drugs are frequent external causes of hearing loss. With no pharmacological treatments currently available, understanding the mechanisms and pathways leading to auditory hair cell (HC) damage and repair is crucial for identifying potential pharmacological targets. Prior research has implicated increased reactive oxygen species (ROS) and inflammation as general mechanisms of hearing loss common to diverse causes. Novel targets of these two key mechanisms of auditory damage may provide new paths toward the prevention and treatment of hearing loss. Pioglitazone, an oral antidiabetic drug from the class of thiazolidinediones, acts as an agonist of the peroxisome proliferator-activated receptor-gamma (PPAR-γ) and is involved in the regulation of lipid and glucose metabolism. PPAR-γ is an important player in repressing the expression of inflammatory cytokines and signaling molecules. We evaluated the effects of pioglitazone in the mouse Organ of Corti (OC) explants to characterize its influence on signaling pathways involved in auditory HC damage. The OC explants was cultured with pioglitazone, gentamicin, or a combination of both agents. Pioglitazone treatment resulted in significant repression of interferon (IFN)-α and -gamma pathways and downstream cytokines, as assessed by RNA sequencing and quantitative PCR gene expression assays. More detailed investigation at the single gene and protein level showed that pioglitazone mediated its anti-inflammatory effects through alterations of the Toll-like receptor (TLR) and STAT pathways. Together, these results indicate that pioglitazone significantly represses IFN and TLR in the cochlea, dampening the activity of gentamicin-induced pathways. These data support our previous results demonstrating significant protection of auditory HCs in the OC explants exposed to pioglitazone and other PPAR-targeted agents.
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Affiliation(s)
| | | | - Vesna Petkovic
- Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Daniel Bodmer
- Department of Biomedicine, University of Basel, Basel, Switzerland.,Clinic for Otolaryngology, Head and Neck Surgery, University Hospital Basel, Basel, Switzerland
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3
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Kucharava K, Brand Y, Albano G, Sekulic-Jablanovic M, Glutz A, Xian X, Herz J, Bodmer D, Fuster DG, Petkovic V. Sodium-hydrogen exchanger 6 (NHE6) deficiency leads to hearing loss, via reduced endosomal signalling through the BDNF/Trk pathway. Sci Rep 2020; 10:3609. [PMID: 32107410 PMCID: PMC7046661 DOI: 10.1038/s41598-020-60262-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 02/07/2020] [Indexed: 01/03/2023] Open
Abstract
Acid-base homeostasis is critical for normal growth, development, and hearing function. The sodium-hydrogen exchanger 6 (NHE6), a protein mainly expressed in early and recycling endosomes, plays an important role in regulating organellar pH. Mutations in NHE6 cause complex, slowly progressive neurodegeneration. Little is known about NHE6 function in the mouse cochlea. Here, we found that all NHE isoforms were expressed in wild-type (WT) mouse cochlea. Nhe6 knockout (KO) mice showed significant hearing loss compared to WT littermates. Immunohistochemistry in WT mouse cochlea showed that Nhe6 was localized in the organ of Corti (OC), spiral ganglion (SG), stria vascularis (SV), and afferent nerve fibres. The middle and the inner ears of WT and Nhe6 KO mice were not different morphologically. Given the putative role of NHE6 in early endosomal function, we examined Rab GTPase expression in early and late endosomes. We found no change in Rab5, significantly lower Rab7, and higher Rab11 levels in the Nhe6 KO OC, compared to WT littermates. Because Rabs mediate TrkB endosomal signalling, we evaluated TrkB phosphorylation in the OCs of both strains. Nhe6 KO mice showed significant reductions in TrkB and Akt phosphorylation in the OC. In addition, we examined genes used as markers of SG type I (Slc17a7, Calb1, Pou4f1, Cal2) and type II neurons (Prph, Plk5, Cacna1g). We found that all marker gene expression levels were significantly elevated in the SG of Nhe6 KO mice, compared to WT littermates. Anti-neurofilament factor staining showed axon loss in the cochlear nerves of Nhe6 KO mice compared to WT mice. These findings indicated that BDNF/TrkB signalling was disrupted in the OC of Nhe6 KO mice, probably due to TrkB reduction, caused by over acidification in the absence of NHE6. Thus, our findings demonstrated that NHEs play important roles in normal hearing in the mammalian cochlea.
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Affiliation(s)
- Krystsina Kucharava
- Department of Biomedicine, and Clinic for Otolaryngology, Head and Neck Surgery, Hospital Basel, University of Basel, Basel, 4031, Switzerland
| | - Yves Brand
- Clinic for Otolaryngology, Head and Neck Surgery, Kantonsspital Graubünden, Chur, 7000, Switzerland
| | - Giuseppe Albano
- Department of Nephrology and Hypertension, Inselspital, Bern University Hospital, and NCCR Transcure, University of Bern, Bern, Switzerland
| | - Marijana Sekulic-Jablanovic
- Department of Biomedicine, and Clinic for Otolaryngology, Head and Neck Surgery, Hospital Basel, University of Basel, Basel, 4031, Switzerland
| | - Andrea Glutz
- Department of Biomedicine, and Clinic for Otolaryngology, Head and Neck Surgery, Hospital Basel, University of Basel, Basel, 4031, Switzerland
| | - Xunde Xian
- Center for Translational Neurodegeneration Research, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Joachim Herz
- Center for Translational Neurodegeneration Research, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Daniel Bodmer
- Department of Biomedicine, and Clinic for Otolaryngology, Head and Neck Surgery, Hospital Basel, University of Basel, Basel, 4031, Switzerland
| | - Daniel G Fuster
- Department of Nephrology and Hypertension, Inselspital, Bern University Hospital, and NCCR Transcure, University of Bern, Bern, Switzerland
| | - Vesna Petkovic
- Department of Biomedicine, and Clinic for Otolaryngology, Head and Neck Surgery, Hospital Basel, University of Basel, Basel, 4031, Switzerland.
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4
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Sekulic-Jablanovic M, Voronkova K, Bodmer D, Petkovic V. Combination of antioxidants and NFAT (nuclear factor of activated T cells) inhibitor protects auditory hair cells from ototoxic insult. J Neurochem 2019; 154:519-529. [PMID: 31755556 DOI: 10.1111/jnc.14921] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 11/08/2019] [Accepted: 11/11/2019] [Indexed: 02/06/2023]
Abstract
Hair cell (HC) degeneration causes hearing loss in millions of people worldwide. Aminoglycoside exposure is one major cause of sensory HC damage. Aminoglycosides generate free radicals within the inner ear, permanently damaging sensory cells, and thus causing hearing loss. Hearing protection requires strategies to overcome the apparently irreversible loss of HCs in mammals. The nuclear factor of activated T cells (NFAT) inhibitor 11R-VIVIT reportedly protects HCs from gentamicin toxicity. Here we investigated whether the combination of 11R-VIVIT with the antioxidant L-carnitine or N-acetylcysteine could protect mouse cochlear HCs from gentamicin damage. Compared to single-component treatment, combined treatment with 11R-VIVIT plus L-carnitine yielded significant protection from gentamicin, and 11R-VIVIT plus N-acetylcysteine provided almost complete protection of HCs from gentamicin. Caspase activity in organ of Corti was significantly reduced by combined treatment with 11R-VIVIT + N-acetylcysteine + gentamicin, compared to 11R-VIVIT + gentamicin or gentamicin alone. Analysis of relative gene expression by qPCR revealed down-regulation of the pro-apoptotic genes Fasl and Casp9, and up-regulation of the antioxidant genes Hmox1 and Nrf2 after treatment with 11R-VIVIT + N-acetylcysteine + gentamicin, compared to single-compound treatment or gentamicin alone in cultures. Selective NFAT inhibition by 11R-VIVIT may be a good strategy for preventing gentamicin-induced HC damage. L-carnitine and N-acetylcysteine, with their ROS-reducing properties, contribute to the synergistic effectiveness with 11R-VIVIT by decreasing ROS-induced NFAT translocation. Our data suggest that a combined approach of NFAT inhibition together with an antioxidant, like N-acetylcysteine, could be useful for hearing loss treatment and/or prevention. Cover Image for this issue: https://doi.org/10.1111/jnc.14759.
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Affiliation(s)
| | | | - Daniel Bodmer
- Department of Biomedicine, University of Basel, Basel, Switzerland.,Clinic for Otolaryngology, Head and Neck Surgery, University Hospital Basel, Basel, Switzerland
| | - Vesna Petkovic
- Department of Biomedicine, University of Basel, Basel, Switzerland
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5
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Huerzeler N, Petkovic V, Sekulic-Jablanovic M, Kucharava K, Wright MB, Bodmer D. Insulin Receptor and Glucose Transporters in the Mammalian Cochlea. Audiol Neurootol 2019; 24:65-76. [PMID: 31117067 DOI: 10.1159/000499561] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 03/07/2019] [Indexed: 11/19/2022] Open
Abstract
Insulin receptors are expressed on nerve cells in the mammalian brain, but little is known about insulin signaling and the expression of the insulin receptor (IR) and glucose transporters in the cochlea. We performed immunohistochemistry and gene/protein expression analysis to characterize the expression pattern of the IR and glucose transporters in the mouse organ of Corti (OC). We also performed glucose uptake assays to explore the action of insulin and the effects of pioglitazone, an insulin sensitizer, on glucose transport in the OC. Western blots of protein extracts from OCs showed high expression of IR and glucose transporter 3 (GLUT3). Immunohistochemistry demonstrated that the IR is specifically expressed in the supporting cells of the OC. GLUT3 was found in outer and inner hair cells, in the basilar membrane (BM), the stria vascularis (SV), Reissner's membrane and spiral ganglion neurons (SGN). Glucose transporter 1 (GLUT1) was detected at low levels in the BM, SV and Reissner's membrane, and showed high expression in the SGN. Fluorescence glucose uptake assays revealed that hair cells take up glucose and that addition of insulin (10 nM or 1 µM) approximately doubled the rate of uptake. Pioglitazone conferred a small but nonsignificant potentiation of glucose uptake at the highest concentration of insulin. Gene expression analysis confirmed expression of IR, GLUT1 and GLUT3 mRNA in the OC. Pioglitazone significantly upregulated IR and GLUT1 mRNA expression, which was further increased by insulin. Together, these data show that insulin-stimulated glucose uptake occurs in the OC and may be associated with upregulation of both the IR and GLUT1.
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Affiliation(s)
- Nathan Huerzeler
- Department of Biomedicine, University of Basel, Basel, Switzerland,
| | - Vesna Petkovic
- Department of Biomedicine, University of Basel, Basel, Switzerland
| | | | | | | | - Daniel Bodmer
- Department of Biomedicine, University of Basel, Basel, Switzerland.,Clinic for Otorhinolaryngology, Head and Neck Surgery, University Hospital Basel, Basel, Switzerland
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6
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Eckhardt J, Bachmann C, Sekulic-Jablanovic M, Enzmann V, Park KH, Ma J, Takeshima H, Zorzato F, Treves S. Extraocular muscle function is impaired in ryr3 -/- mice. J Gen Physiol 2019; 151:929-943. [PMID: 31085573 PMCID: PMC6605690 DOI: 10.1085/jgp.201912333] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 04/13/2019] [Indexed: 01/16/2023] Open
Abstract
Extraocular muscles are specialized skeletal muscles expressing a particular set
of proteins involved in calcium homeostasis, including RYR3. Eckhardt et al.
investigate extraocular muscle function in
ryr3−/− mice and show that
ablation of RYR3 significantly impacts vision. Calcium is an ubiquitous second messenger mediating numerous physiological
processes, including muscle contraction and neuronal excitability.
Ca2+ is stored in the ER/SR and is released into the cytoplasm
via the opening of intracellular inositol trisphosphate receptor and ryanodine
receptor calcium channels. Whereas in skeletal muscle, isoform 1 of the RYR is
the main channel mediating calcium release from the SR leading to muscle
contraction, the function of ubiquitously expressed ryanodine receptor 3 (RYR3)
is far from clear; it is not known whether RYR3 plays a role in
excitation–contraction coupling. We recently reported that human
extraocular muscles express high levels of RYR3, suggesting that such muscles
may be useful to study the function of this isoform of the Ca2+
channel. In the present investigation, we characterize the visual function of
ryr3−/− mice. We observe that
ablation of RYR3 affects both mechanical properties and calcium homeostasis in
extraocular muscles. These changes significantly impact vision. Our results
reveal for the first time an important role for RYR3 in extraocular muscle
function.
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Affiliation(s)
- Jan Eckhardt
- Department of Anesthesia, Basel University Hospital, Basel, Switzerland.,Department of Biomedicine, Basel University Hospital, Basel, Switzerland
| | - Christoph Bachmann
- Department of Anesthesia, Basel University Hospital, Basel, Switzerland.,Department of Biomedicine, Basel University Hospital, Basel, Switzerland
| | | | - Volker Enzmann
- Department of Ophthalmology, University Hospital of Bern, Bern, Switzerland.,Department of Biomedical Research, University of Bern, Bern, Switzerland
| | - Ki Ho Park
- Department of Surgery, Davis Heart & Lung Research Institute, The Ohio State University Medical Center, Columbus, OH
| | - Jianjie Ma
- Department of Surgery, Davis Heart & Lung Research Institute, The Ohio State University Medical Center, Columbus, OH
| | - Hiroshi Takeshima
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Francesco Zorzato
- Department of Anesthesia, Basel University Hospital, Basel, Switzerland.,Department of Biomedicine, Basel University Hospital, Basel, Switzerland.,Department of Life Sciences, Microbiology and Applied Pathology section, University of Ferrara, Ferrara, Italy
| | - Susan Treves
- Department of Anesthesia, Basel University Hospital, Basel, Switzerland .,Department of Biomedicine, Basel University Hospital, Basel, Switzerland.,Department of Life Sciences, Microbiology and Applied Pathology section, University of Ferrara, Ferrara, Italy
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7
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Sekulic-Jablanovic M, Petkovic V, Wright MB, Kucharava K, Huerzeler N, Levano S, Brand Y, Leitmeyer K, Glutz A, Bausch A, Bodmer D. Effects of peroxisome proliferator activated receptors (PPAR)-γ and -α agonists on cochlear protection from oxidative stress. PLoS One 2017; 12:e0188596. [PMID: 29182629 PMCID: PMC5705132 DOI: 10.1371/journal.pone.0188596] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 11/09/2017] [Indexed: 01/22/2023] Open
Abstract
Various insults cause ototoxicity in mammals by increasing oxidative stress leading to apoptosis of auditory hair cells (HCs). The thiazolidinediones (TZDs; e.g., pioglitazone) and fibrate (e.g., fenofibrate) drugs are used for the treatment of diabetes and dyslipidemia. These agents target the peroxisome proliferator-activated receptors, PPARγ and PPARα, which are transcription factors that influence glucose and lipid metabolism, inflammation, and organ protection. In this study, we explored the effects of pioglitazone and other PPAR agonists to prevent gentamicin-induced oxidative stress and apoptosis in mouse organ of Corti (OC) explants. Western blots showed high levels of PPARγ and PPARα proteins in mouse OC lysates. Immunofluorescence assays indicated that PPARγ and PPARα proteins are present in auditory HCs and other cell types in the mouse cochlea. Gentamicin treatment induced production of reactive oxygen species (ROS), lipid peroxidation, caspase activation, PARP-1 cleavage, and HC apoptosis in cultured OCs. Pioglitazone mediated its anti-apoptotic effects by opposing the increase in ROS induced by gentamicin, which inhibited the subsequent formation of 4-hydroxy-2-nonenal (4-HNE) and activation of pro-apoptotic mediators. Pioglitazone mediated its effects by upregulating genes that control ROS production and detoxification pathways leading to restoration of the reduced:oxidized glutathione ratio. Structurally diverse PPAR agonists were protective of HCs. Pioglitazone (PPARγ-specific), tesaglitazar (PPARγ/α-specific), and fenofibric acid (PPARα-specific) all provided >90% protection from gentamicin toxicity by regulation of overlapping subsets of genes controlling ROS detoxification. This study revealed that PPARs play important roles in the cochlea, and that PPAR-targeting drugs possess therapeutic potential as treatment for hearing loss.
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Affiliation(s)
| | - Vesna Petkovic
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
| | | | - Krystsina Kucharava
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
| | - Nathan Huerzeler
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
| | - Soledad Levano
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
| | - Yves Brand
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
- Clinic for Otolaryngology, Head and Neck Surgery, University Hospital Basel, Basel, Switzerland
| | - Katharina Leitmeyer
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
| | - Andrea Glutz
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
| | | | - Daniel Bodmer
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
- Clinic for Otolaryngology, Head and Neck Surgery, University Hospital Basel, Basel, Switzerland
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8
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Bodmer D, Perkovic A, Sekulic-Jablanovic M, Wright MB, Petkovic V. Pasireotide prevents nuclear factor of activated T cells nuclear translocation and acts as a protective agent in aminoglycoside-induced auditory hair cell loss. J Neurochem 2016; 139:1113-1123. [PMID: 27787949 DOI: 10.1111/jnc.13880] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 10/18/2016] [Accepted: 10/19/2016] [Indexed: 12/23/2022]
Abstract
Hearing impairment is a global health problem with a high socioeconomic impact. Damage to auditory hair cells (HCs) in the inner ear as a result of aging, disease, trauma, or toxicity, underlies the majority of cases of sensorineural hearing loss. Previously we demonstrated that the Ca2+ -sensitive neuropeptide, somatostatin (SST), and an analog, octreotide, protect HCs from gentamicin-induced cell death in vitro. Aminoglycosides such as gentamicin trigger a calcium ion influx (Ca2+ ) that activates pro-apoptotic signaling cascades in HCs. SST binding to the G-protein-coupled receptors (SSTR1-SSTR5) that are directly linked to voltage-dependent Ca2+ channels inhibits Ca2+ channel activity and associated downstream events. Here, we report that the SST analog pasireotide, a high affinity ligand to SSTRs 1-3, and 5, with a longer half-life than octreotide, prevents gentamicin-induced HC death in the mouse organ of Corti (OC). Explant experiments using OCs derived from SSTR1 and SSTR1and 2 knockout mice, revealed that SSTR2 mediates pasireotide's anti-apoptotic effects. Mechanistically, pasireotide prevented a nuclear translocation of the Ca2+ -sensitive transcription factor, nuclear factor of activated T cells (NFAT), which is ordinarily provoked by gentamicin in OC explants. Direct inhibition of NFAT with 11R-VIVIT also prevented the gentamicin-dependent nuclear translocation of NFAT and apoptosis. Both pasireotide and 11R-VIVIT partially reversed the effects of gentamicin on the expression of downstream survival targets (NMDA receptor and the regulatory subunit of phosphatidylinositol-4,5-bisphosphate 3-kinase, PI3K). These data suggest that SST analogs antagonize aminoglycoside-induced cell death in an NFAT-dependent fashion. SST analogs and NFAT inhibitors may therefore offer new therapeutic possibilities for the treatment of hearing loss.
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Affiliation(s)
- Daniel Bodmer
- Department of Biomedicine and the Clinic for Otorhinolaryngology, University Hospital Basel, Basel, Switzerland
| | - Adrijana Perkovic
- Department of Biomedicine and the Clinic for Otorhinolaryngology, University Hospital Basel, Basel, Switzerland
| | - Marijana Sekulic-Jablanovic
- Department of Biomedicine and the Clinic for Otorhinolaryngology, University Hospital Basel, Basel, Switzerland
| | | | - Vesna Petkovic
- Department of Biomedicine and the Clinic for Otorhinolaryngology, University Hospital Basel, Basel, Switzerland
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9
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Lopez R, Byrne S, Vukcevic M, Sekulic-Jablanovic M, Xu L, Brink M, Alamelu J, Voermans N, Snoeck M, Clement E, Muntoni F, Zhou H, Radunovic A, Mohammed S, Wraige E, Zorzato F, Treves S, Jungbluth H. A novel bleeding disorder associated with RYR1 mutations. Neuromuscul Disord 2016. [DOI: 10.1016/j.nmd.2016.06.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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10
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Lopez RJ, Byrne S, Vukcevic M, Sekulic-Jablanovic M, Xu L, Brink M, Alamelu J, Voermans N, Snoeck M, Clement E, Muntoni F, Zhou H, Radunovic A, Mohammed S, Wraige E, Zorzato F, Treves S, Jungbluth H. An RYR1 mutation associated with malignant hyperthermia is also associated with bleeding abnormalities. Sci Signal 2016; 9:ra68. [PMID: 27382027 DOI: 10.1126/scisignal.aad9813] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Malignant hyperthermia is a potentially fatal hypermetabolic disorder triggered by halogenated anesthetics and the myorelaxant succinylcholine in genetically predisposed individuals. About 50% of susceptible individuals carry dominant, gain-of-function mutations in RYR1 [which encodes ryanodine receptor type 1 (RyR1)], though they have normal muscle function and no overt clinical symptoms. RyR1 is predominantly found in skeletal muscle but also at lower amounts in immune and smooth muscle cells, suggesting that RYR1 mutations may have a wider range of effects than previously suspected. Mild bleeding abnormalities have been described in patients with malignant hyperthermia carrying gain-of-function RYR1 mutations. We sought to determine the frequency and molecular basis for this symptom. We found that some patients with specific RYR1 mutations had abnormally high bleeding scores, whereas their healthy relatives did not. Knock-in mice with the malignant hyperthermia susceptibility RYR1 mutation Y522S (MHS RYR1Y522S) had longer bleeding times than their wild-type littermates. Primary vascular smooth muscle cells from RYR1Y522S knock-in mice exhibited a higher frequency of subplasmalemmal Ca(2+) sparks, leading to a more negative resting membrane potential. The bleeding defect of RYR1Y522S mice and of one patient was reversed by treatment with the RYR1 antagonist dantrolene, and Ca(2+) sparks in primary vascular smooth muscle cells from the MHS RYR1Y522S mice were blocked by ryanodine or dantrolene. Thus, RYR1 mutations may lead to prolonged bleeding by altering vascular smooth muscle cell function. The reversibility of the bleeding phenotype emphasizes the potential therapeutic value of dantrolene in the treatment of such bleeding disorders.
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Affiliation(s)
- Rubén J Lopez
- Departments of Biomedicine and Anesthesia, Basel University Hospital, Hebelstrasse 20, 4031 Basel, Switzerland
| | - Susan Byrne
- Department of Paediatric Neurology, Neuromuscular Service, Evelina Children's Hospital, St Thomas' Hospital, London SE1 7EH, UK
| | - Mirko Vukcevic
- Departments of Biomedicine and Anesthesia, Basel University Hospital, Hebelstrasse 20, 4031 Basel, Switzerland. Department of Biomedicine, Basel University Hospital, Hebelstrasse 20, 4031 Basel, Switzerland
| | - Marijana Sekulic-Jablanovic
- Departments of Biomedicine and Anesthesia, Basel University Hospital, Hebelstrasse 20, 4031 Basel, Switzerland
| | - Lifen Xu
- Department of Biomedicine, Basel University Hospital, Hebelstrasse 20, 4031 Basel, Switzerland
| | - Marijke Brink
- Department of Biomedicine, Basel University Hospital, Hebelstrasse 20, 4031 Basel, Switzerland
| | - Jay Alamelu
- Department of Haematology, Evelina Children's Hospital, St Thomas' Hospital, London SE1 7EH, UK
| | - Nicol Voermans
- Department of Neurology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Marc Snoeck
- National MH Investigation Unit, Department of Anesthesiology, Canisius Wilhelmina Hospital, 6532 Nijmegen, Netherlands
| | - Emma Clement
- Department of Clinical Genetics, Guy's Hospital, London SE1 7EH, UK
| | - Francesco Muntoni
- Dubowitz Neuromuscular Centre, Institute of Child Health, University College London, London WC1N 1EH, UK
| | - Haiyan Zhou
- Dubowitz Neuromuscular Centre, Institute of Child Health, University College London, London WC1N 1EH, UK
| | | | - Shehla Mohammed
- Department of Clinical Genetics, Guy's Hospital, London SE1 7EH, UK
| | - Elizabeth Wraige
- Department of Paediatric Neurology, Neuromuscular Service, Evelina Children's Hospital, St Thomas' Hospital, London SE1 7EH, UK
| | - Francesco Zorzato
- Departments of Biomedicine and Anesthesia, Basel University Hospital, Hebelstrasse 20, 4031 Basel, Switzerland. Department of Life Sciences, General Pathology Section, University of Ferrara, Via Borsari 46, 44100 Ferrara, Italy
| | - Susan Treves
- Departments of Biomedicine and Anesthesia, Basel University Hospital, Hebelstrasse 20, 4031 Basel, Switzerland. Department of Life Sciences, General Pathology Section, University of Ferrara, Via Borsari 46, 44100 Ferrara, Italy
| | - Heinz Jungbluth
- Department of Paediatric Neurology, Neuromuscular Service, Evelina Children's Hospital, St Thomas' Hospital, London SE1 7EH, UK. Randall Division of Cell and Molecular Biophysics, Muscle Signalling Section, King's College, London SE1 1UL, UK. Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London SE5 9RX, UK
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Sekulic-Jablanovic M, Ullrich ND, Goldblum D, Palmowski-Wolfe A, Zorzato F, Treves S. Functional characterization of orbicularis oculi and extraocular muscles. J Biophys Biochem Cytol 2016. [DOI: 10.1083/jcb.2133oia96] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Sekulic-Jablanovic M, Ullrich ND, Goldblum D, Palmowski-Wolfe A, Zorzato F, Treves S. Functional characterization of orbicularis oculi and extraocular muscles. J Gen Physiol 2016; 147:395-406. [PMID: 27069119 PMCID: PMC4845688 DOI: 10.1085/jgp.201511542] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 03/25/2016] [Indexed: 12/17/2022] Open
Abstract
Facial muscles are skeletal muscles that control facial expression. Sekulic-Jablanovic et al. characterize orbicularis oculi and extraocular muscles and find divergence in the expression of key molecules for muscle function between facial, extraocular, and quadriceps muscles. The orbicularis oculi are the sphincter muscles of the eyelids and are involved in modulating facial expression. They differ from both limb and extraocular muscles (EOMs) in their histology and biochemistry. Weakness of the orbicularis oculi muscles is a feature of neuromuscular disorders affecting the neuromuscular junction, and weakness of facial muscles and ptosis have also been described in patients with mutations in the ryanodine receptor gene. Here, we investigate human orbicularis oculi muscles and find that they are functionally more similar to quadriceps than to EOMs in terms of excitation–contraction coupling components. In particular, they do not express the cardiac isoform of the dihydropyridine receptor, which we find to be highly expressed in EOMs where it is likely responsible for the large depolarization-induced calcium influx. We further show that human orbicularis oculi and EOMs express high levels of utrophin and low levels of dystrophin, whereas quadriceps express dystrophin and low levels of utrophin. The results of this study highlight the notion that myotubes obtained by explanting satellite cells from different muscles are not functionally identical and retain the physiological characteristics of their muscle of origin. Furthermore, our results indicate that sparing of facial and EOMs in patients with Duchenne muscular dystrophy is the result of the higher levels of utrophin expression.
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Affiliation(s)
- Marijana Sekulic-Jablanovic
- Department of Anesthesia, Basel University Hospital, 4031 Basel, Switzerland Department of Biomedicine, Basel University Hospital, 4031 Basel, Switzerland
| | - Nina D Ullrich
- Institute of Physiology and Pathophysiology, Department of Cardiovascular Physiology, University of Heidelberg, 69120 Heidelberg, Germany
| | - David Goldblum
- Eye Clinic, Basel University and Basel University Hospital, 4031 Basel, Switzerland
| | - Anja Palmowski-Wolfe
- Eye Clinic, Basel University and Basel University Hospital, 4031 Basel, Switzerland
| | - Francesco Zorzato
- Department of Anesthesia, Basel University Hospital, 4031 Basel, Switzerland Department of Biomedicine, Basel University Hospital, 4031 Basel, Switzerland Department of Life Sciences and Biotechnology, General Pathology Section, University of Ferrara, 44100 Ferrara, Italy
| | - Susan Treves
- Department of Anesthesia, Basel University Hospital, 4031 Basel, Switzerland Department of Biomedicine, Basel University Hospital, 4031 Basel, Switzerland Department of Life Sciences and Biotechnology, General Pathology Section, University of Ferrara, 44100 Ferrara, Italy
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Rokach O, Sekulic-Jablanovic M, Voermans N, Wilmshurst J, Pillay K, Heytens L, Zhou H, Muntoni F, Gautel M, Nevo Y, Mitrani-Rosenbaum S, Attali R, Finotti A, Gambari R, Mosca B, Jungbluth H, Zorzato F, Treves S. Epigenetic changes as a common trigger of muscle weakness in congenital myopathies. Hum Mol Genet 2015; 24:4636-47. [DOI: 10.1093/hmg/ddv195] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 05/22/2015] [Indexed: 12/13/2022] Open
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