BUSCADOR RECOLECTA

Animal models are invaluable for biomedical research, especially in the context of rare diseases, which have a very low prevalence and are often complex. Concretely mouse models provide key information on rare disease mechanisms and therapeutic strategies that cannot be obtained by using only alternative methods, and greatly contribute to accelerate the development of new therapeutic options for rare diseases. Despite this, the use of experimental animals remains controversial. The combination of respectful management, ethical laws and transparency regarding animal experimentation contributes to improve society's opinion about biomedical research and positively impacts on research quality, which eventually also benefits patients. Here we present examples of current advances in preclinical research in rare diseases using mouse models, together with our perspective on future directions and challenges., This work was supported by a grant from the Center for Biomedical Research on Rare Diseases (CIBERER) (ER18GDT761) to SM-C. Additional support came from: Multi Target and View FEDER/CM-B2017/BMD-3688 and MINECO/FEDER SAF2017-86107-R grants to SM-C and IV-N; CERCA Program/Generalitat de Catalunya, Autonomous Government of Catalonia (2017SGR1206), and CIBERER (ACCI18-27) to AP; Miguel Servet program CPII16/00016 (Instituto de Salud Carlos III co-funded by European Social Fund ESF) to SF; CNIC (ISCIII, Ministerio de Ciencia, Innovación y Universidades), Pro CNIC Foundation, Severo Ochoa Center of Excellence (SEV-2015-0505) to BI and EO; Generalitat de Catalunya (Grups consolidats 2017 SGR 926) to MD. EO was beneficiary of a grant from “Programa de Atracción de Talento” of Comunidad de Madrid (2017-T1/BMD-5185). SM-C holds a ISCiii CIBER postdoctoral researcher contract. The work at CRG was supported by grants from the Spanish Ministry of Science and Innovation to the EMBL partnership, the Centro de Excelencia Severo Ochoa and the CERCA Programme/Generalitat de Catalunya., Sí

Embryonic development requires the coordinated regulation of apoptosis, survival, autophagy, proliferation and differentiation programs. Senescence has recently joined the cellular processes required to master development, in addition to its well-described roles in cancer and ageing. Here, we show that senescent cells are present in a highly regulated temporal pattern in the developing vertebrate inner ear, first, surrounding the otic pore and, later, in the otocyst at the endolymphatic duct. Cellular senescence is associated with areas of increased apoptosis and reduced proliferation consistent with the induction of the process when the endolymphatic duct is being formed. Modulation of senescence disrupts otic vesicle morphology. Transforming growth factor beta (TGF?) signaling interacts with signaling pathways elicited by insulin-like growth factor type 1 (IGF-1) to jointly coordinate cellular dynamics required for morphogenesis and differentiation. Taken together, these results show that senescence is a natural occurring process essential for early inner ear development., Funding: This work was supported by the European Commission FP7-PEOPLE-2013-IAPP TARGEAR to IVN and by the Spanish MINECO/FEDER SAF2017-86107-R to IVN and MM. SP was supported by a FPI predoctoral fellowship (BES-2015-071311) funded by MINECO/European Social Fund.

Betaine-homocysteine S-methyltransferases (BHMTs) are methionine cycle enzymes that remethylate homocysteine; hence, their malfunction leads to hyperhomocysteinemia. Epidemiologic and experimental studies have revealed a correlation between hyperhomocysteinemia and hearing loss. Here, we have studied the expression of methionine cycle genes in the mouse cochlea and the impact of knocking out the Bhmt gene in the auditory receptor. We evaluated age-related changes in mouse hearing by recording auditory brainstem responses before and following exposure to noise. Also, we measured cochlear cytoarchitecture, gene expression by RNA-arrays and quantitative RT-PCR, and metabolite levels in liver and plasma by HPLC. Our results indicate that there is an age-dependent strain-specific expression of methionine cycle genes in the mouse cochlea and a further regulation during the response to noise damage. Loss of Bhmt did not cause an evident impact in the hearing acuity of young mice, but it produced higher threshold shifts and poorer recovery following noise challenge. Hearing loss was associated with increased cochlear injury, outer hair cell loss, altered expression of cochlear methionine cycle genes, and hyperhomocysteinemia. Our results suggest that BHMT plays a central role in the homeostasis of cochlear methionine metabolism and that Bhmt2 up-regulation could carry out a compensatory role in cochlear protection against noise injury in the absence of BHMT.—Partearroyo, T., Murillo-Cuesta, S., Vallecillo, N., Bermúdez-Muñoz, J. M., Rodríguez-de la Rosa, L., Mandruzzato, G., Celaya, A. M., Zeisel, S. H., Pajares, M. A., Varela-Moreiras, G., Varela-Nieto, I. Betaine-homocysteine S-methyltransferase deficiency causes increased susceptibility to noise-induced hearing loss associated to plasma hyperhomocysteinemia., This work was supported by the Spanish Ministerio de Economía y Competitividad (MINECO)/
FEDER SAF2017-86107-R to I.V.-N., U.S. National Institutes of Health (NIH), National Institute of Diabetes and Digestive and Kidney Diseases (Grant DK056350 to S.H.Z.), CEU-Banco Santander precompetitive project (MUSPB047) and CEUBanco Santander consolidation project (MBS18C12) to T.P., and Puleva BioFoods (to I.V.-N., G.V.-M., and M.A.P.). G.M. was supported by TARGEAR (FP7 PEOPLE 2013 IAPP612261)., Peer reviewed

The development of the inner ear complex cytoarchitecture and functional geometry requires the exquisite coordination of a variety of cellular processes in a temporal manner. At early stages of inner ear development several rounds of cell proliferation in the otocyst promote the growth of the structure. The apoptotic program is initiated in exceeding cells to adjust cell type numbers. Apoptotic cells are cleared by phagocytic cells that recognize the phosphatidylserine residues exposed in the cell membrane thanks to the energy supplied by autophagy. Specific molecular programs determine hair and supporting cell fate, these populations are responsible for the functions of the adult sensory organ: detection of sound, position and acceleration. The neurons that transmit auditory and balance information to the brain are also born at the otocyst by neurogenesis facilitated by autophagy. Cellular senescence participates in tissue repair, cancer and aging, situations in which cells enter a permanent cell cycle arrest and acquire a highly secretory phenotype that modulates their microenvironment. More recently, senescence has also been proposed to take place during vertebrate development in a limited number of transitory structures and organs; among the later, the endolymphatic duct in the inner ear. Here, we review these cellular processes during the early development of the inner ear, focusing on how the most recently described cellular senescence participates and cooperates with proliferation, apoptosis and autophagy to achieve otic morphogenesis and differentiation., This work has been supported by FP7-IAPP2013-TARGEAR to IVN, Spanish MINECO/FEDER SAF2017-86107-R to IVN and MM and SAF2015-65960-P to IP., Peer reviewed

Embryonic development requires the coordinated regulation of apoptosis, survival, autophagy, proliferation and differentiation programs. Senescence has recently joined the cellular processes required to master development, in addition to its well-described roles in cancer and ageing. Here, we show that senescent cells are present in a highly regulated temporal pattern in the developing vertebrate inner ear, first, surrounding the otic pore and, later, in the otocyst at the endolymphatic duct. Cellular senescence is associated with areas of increased apoptosis and reduced proliferation consistent with the induction of the process when the endolymphatic duct is being formed. Modulation of senescence disrupts otic vesicle morphology. Transforming growth factor beta (TGFβ) signaling interacts with signaling pathways elicited by insulin-like growth factor type 1 (IGF-1) to jointly coordinate cellular dynamics required for morphogenesis and differentiation. Taken together, these results show that senescence is a natural occurring process essential for early inner ear development., This work was supported by the European Commission FP7-PEOPLE-2013-IAPP TARGEAR to IVN and by the Spanish MINECO/FEDER SAF2017-86107-R to IVN and MM. SP was supported by a FPI predoctoral fellowship (BES-2015-071311) funded by MINECO/European Social Fund., Peer reviewed

Mitogen-activated protein kinases (MAPK) such as p38 and the c-Jun N-terminal kinases (JNKs) are activated during the cellular response to stress signals. Their activity is regulated by the MAPK-phosphatase 1 (DUSP1), a key component of the anti-inflammatory response. Stress kinases are well-described elements of the response to otic injury and the otoprotective potential of JNK inhibitors is being tested in clinical trials. By contrast, there are no studies exploring the role of DUSP1 in hearing and hearing loss. Here we show that Dusp1 expression is age-regulated in the mouse cochlea. Dusp1 gene knock-out caused premature progressive hearing loss, as confirmed by auditory evoked responses in Dusp1-/- mice. Hearing loss correlated with cell death in hair cells, degeneration of spiral neurons and increased macrophage infiltration. Dusp1-/- mouse cochleae showed imbalanced redox status and dysregulated expression of cytokines. These data suggest that DUSP1 is essential for cochlear homeostasis in the response to stress during ageing., This work has been supported by Spanish MINECO/FEDER SAF2017-86107-R to IVN and P17-01401 (Fondo de Investigaciones Sanitarias, Instituto de Salud Carlos III, Spain) supported by FEDER funds to RP and IS-P. SM, and LR hold CIBER ISCIII researcher contracts. AMC was supported by contracts from FP7-PEOPLE-2013-IAPP TARGEAR and FEDER/CIBERER., Peer reviewed

Resumen del trabajo presentado al 42nd Congress of the Spanish Society of Biochemistry and Molecular Biology (SEBBM), celebrado en Madrid del 16 al 19 de julio de 2019., Sphingolipids are bioactive lipids whose role has progressed from being a mere component of cell membranes to be active participants in every cell biological process. Ceramide is the central backbone
precursor of all complex bioactive sphingolipids. A myriad of functions have been described for ceramide: cell death, cell differentiation, cell proliferation, senescence, autophagy, cell cycle arrest and
so on. We have addressed the study of the role that ceramide plays in the early development of inner ear in cultures of otic vesicles (OV), the primordium of this organ. This ex vivo culture mimics the in vivo development, maintaining the spatiotemporal pattern of morphogenesis. We had previously shown that a synthetic short-chain ceramide analogue was a potent inductor of apoptosis in OV cultures.
The action of ceramide is finished by its phosphorylation to ceramide-1-phosphate (C1P), a reaction catalysed by ceramide kinase (CERK). C1P has been reported to be cytoprotector in OV cultures. In the chicken embryo, the insulin-like growth factor -1 (IGF-1) is required for the survival and differentiation of epithelial auditory precursors. In this work we have studied whether the pro-survival role of IGF- 1 are due to the generation of C1P. To tackle the study we have used a specific inhibitor of CERK (NVP-231). Our results show that CERK is expressed during the early inner ear development in chicken. The inhibition of CERK decreased the OV size, reduced proliferation and increased cell cycle arrest followed by cell death. The inhibition of CERK also altered the neurogenesis in the acoustic
vestibular ganglion (AVG). Taken together, these results would confirm the involvement of C1P in the morphogenesis and maintenance of the OV and AVG. The exogenous IGF-1 treatment counteracted
partially the effect of the inhibitor, suggesting its protective role through CERK stimulation and C1P production., This work was supported by Spanish Ministerio de Economía, Industria y Competitividad (SAF2017-86107-RFEDER) to MM and IVN., Peer reviewed

Resumen del póster presentado al 42nd Congress of the Spanish Society of Biochemistry and Molecular Biology (SEBBM), celebrado en Madrid del 16 al 19 de julio de 2019., Ageing of the auditory system is associated with the incremental production of reactive oxygen species (ROS) and the accumulation of oxidative-derived damage in macromolecules, which contribute to cellular malfunction, compromise cell viability and, finally, causes functional decline. The cellular detoxification power partially relies in the production of the cofactor for the activity of key antioxidant enzymes NADPH. This is mainly produced by the glucose-6-phosphate dehydrogenase (G6PD), an enzyme that catalyzes the rate-limiting step in the pentose phosphate pathway. We show here that the transgenic mouse hG6PD-Tg, which shows enhanced NADPH production along life, maintains lower auditory thresholds than wild type mice during ageing. G6PD overexpression preserves irreplaceable cochlear cell populations, thus hG6PD-Tg mice exhibit significantly higher number of inner and outer hair cells (OHC) and more widespread OHC innervation than wild type mice. Transcripts for antioxidant enzymes were significantly increased in 3-month old hG6PD-Tg, particularly remarkable those of glutathione reductase and thioredoxin reductase 1, whose activity depends on NADPH availability. Accordingly, tyrosine modification by nitration in proteins was reduced in 9-month old G6PD-Tg compared with wild type mice. As well as lesser TUNEL positive apoptotic cells were detected in whole mount preparations of the organ of Corti of hG6PD-Tg mice. Western blotting analysis of cochlear extracts further showed increased survival and reduced pro-apoptotic signaling in the transgenic versus the wild type mice. In conclusion, we propose that NADPH overproduction from an early stage is an efficient mechanism to maintain the balance between the generation of ROS and the cell detoxification power along ageing and, therefore to prevent hearing loss progression., This work was supported by FP7-2013-TARGEAR and FEDER/SAF 2014-AGEAR and 2017-HEARCODE., Peer Reviewed

Resumen del póster presentado al 42nd Congress of the Spanish Society of Biochemistry and Molecular Biology (SEBBM), celebrado en Madrid del 16 al 19 de julio de 2019., Hearing loss is the most common sensory deficit in the human population. Mutations in the gene coding for IGF-1 cause sensorineural hearing loss in man and mice. Actions of IGF-1 are mediated
by binding to its high affinity transmembrane receptor, IGF1R. This interaction typically leads to the activation of the PI3K-AKT pathway and of the MAPK-ERK cascade. To gain insight into the molecular mechanisms involved in IGF-1 downstream signaling in the sensory hair cells, we have used HEI-OC1 (House Ear Institute-Organ of Corti 1), a cell line derived from the auditory organ of the transgenic ImmortomouseTMat postnatal day 7. The study of the relative expression of genes of the IGF system by RT-qPCR showed that IGF system factors and receptors are expressed in HEI-OC1 and that Igf1 transcripts are more abundant than those of Igf2 and Ins1/ 2. We also studied the cellular actions
and downstream signaling pathways of IGF-1. Cell cycle and apoptosis were studied by flow cytometry and immunohistochemistry, whilst activation of target proteins was measured by Western blotting. The consequences of blockage of IGF-1 actions were analyzed by using specific IGF1R inhibitors and XTT assay. IGF-1 increased survival, proliferation, as well as glucose metabolism and protein synthesis, whereas autophagic flux was decreased and apoptosis inhibited. In conclusion, HEI-OC1 cells can be used as a model to understand the actions of IGF-1 in hair cells, to identify novel targets and to unravel the molecular mechanisms involved in IGF-1 deficiency-associated otic damage., This work was supported by the Spanish Ministerio de Economía y Competitividad (MINECO)/FEDER
SAF2017-86107-R. AGM holds a MECD FPU16/03308 fellowship., Peer reviewed

Resumen del trabajo presentado al 42st Annual Association for Research in Otolaryngology (ARO) MidWinter Meeting, celebrado en Baltimore, Maryland (USA) del 9 al 13 de febrero de 2019., Nutritional imbalance is an emerging causative factor for deafness and several epidemiological and experimental studies have linked alterations in methionine metabolism caused by folic acid and/or vitamin B12 deficiencies with age-related, noiseinduced or sudden hearing loss. Betaine homocysteine S-methyltransferases (BHMTs) are methionine cycle enzymes that remethylate homocysteine, hence their malfunction leads to hyperhomocysteinemia. Here, we have studied the expression of methionine cycle genes in the mouse cochlea and the impact of knocking out the Bhmt gene in the auditory receptor. We evaluated age-related changes in mouse hearing by recording auditory brainstem responses at different moments from embryonic to adult stages, and following exposure to noise. Also we measured cochlear cytoarchitecture, gene expression by RNA-arrays and RT-qPCR, and metabolite levels in liver and plasma by HPLC. Our results indicate that there is an age-dependent strain-specific expression of methionine cycle genes in the mouse cochlea and a further regulation during the response to noise damage. Loss of Bhmt did not cause an evident impact in the hearing acuity of young mice, but it produced higher threshold shifts and poorer
recovery following noise challenge. Hearing loss was associated with increased cochlear injury, altered expression of cochlear methionine cycle genes and hyperhomocysteinemia. Our results suggest that BHMT plays a central role in the homeostasis of cochlear methionine metabolism and that Bhmt2 upregulation could carry out a compensatory role in cochlear protection against noise injury in the absence of BHMT., Work supported by the Spanish MINECO/FEDER SAF2017-86107-R grant to IVN, U.S. National Institutes of Health DK056350 to SZ, and CEU-Banco Santander precompetitive (MUSPB047) and consolidation (MBS18C12) project to TP., Peer Reviewed

Resumen del trabajo presentado al 42st Annual Association for Research in Otolaryngology (ARO) MidWinter Meeting, celebrado en Baltimore, Maryland (USA) del 9 al 13 de febrero de 2019., P38 mitogen-activated protein (MAP) kinases p38α, β, γ and δ are codified by Mapk14, 11, 12 and 13 genes, respectively. P38 kinases are activated by phosphorylation in response to a variety of extracellular stress stimuli that transduce to the nuclei. The MAPK14 (p38a) isoform is ubiquitously expressed and is critical for mammalian embryonic development. MAPK14 participates in the cochlear response to stressors like cisplatin, UV radiation or noise exposure. MAPK14 expression and activity also increase as a consequence of Igf1 deletion in mice in association with hearing loss
and cellular apoptosis. We have studied the expression pattern of the four p38 isoforms along ageing in wild type and knock out Igf1 null mice, to show that they are age- and IGF-1- regulated. To further explore the role of Mapk14 in the cochlea, we have studied the Mapk14lox/loxRERTnERT/ERT conditional knock out mouse and cell lines derived from embryonic fibroblasts. Mapk14 knock out mice auditory brainstem responses (ABR) recording showed that ABR thresholds do not vary upon Mapk14 deletion induced by tamoxifen treatment. RT-qPCR gene expression studies of the p38 isoforms indicated that other isoforms are induced and maybe taking over MAPK14 cochlear functions. P38 isoforms relative expression levels also varied in Mapk14-knock out fibroblasts, as well as the transcripts for MEF2, FoxM1 and FoxG1, which are also altered in the cochlea of Igf1-null mice. Finally, we assessed the response to noise-induced injury in Cre/loxP Mapk14 knock out mice before and after noise exposure. Interestingly, mice with total or partial deletion of Mapk14 exposed to violet noise at an intensity of 105 dB SPL during 30 minutes showed a better recovery of hearing thresholds than wild type mice. These data suggest that MAPK14 plays a central role in the progression of cochlear damage after noise exposure., Research was supported by Spanish MINECO/FEDER SAF2017-86107-R and EU FP7-PEOPLE-TARGEAR grants to IV-N. LRR and SMC hold CIBERER contracts. AGM holds a MECD FPU fellowship., Peer Reviewed

Resumen del póster presentado al 6th Symposium on Biomedical Research: Advances and Perspectives in Molecular Endocrinology "In Homage to Gabriella Morreale", celebrado en el Instituto de Investigaciones Biomédicas Alberto Sols (IIBM-CSIC) el 31 de mayo de 2019., World Health Organization estimates that around 466 million people worldwide have disabling hearing loss (HL), and 34 million of these are children. The most common is sensorineural hearing loss (SNHL), a heterogeneous disorder which is produced mainly by the irreversible loss of sensory cells or neurons in the cochlea. Insulin like growth factor type 1 (IGF-1) is a neurotrophic factor key for the regulation of postnatal cochlear growth and differentiation. Human IGF-1 deficiency is a rare disease (ORPHA73272) associated with growth retardation, microcephaly and SNHL. The mouse model lacking the Igf1 gene reproduces the syndrome and presents dwarfism and SNHL. IGF-1 deficiency causes important cellular alterations in the mouse cochlea, such as the early apoptosis of auditory neurons and the deficit in myelination. Analysis of downstream signalling in the Igf1-/- cochlea has shown the activation of p38 MAPK pathway, involved in response to stress, whereas ERK1/2 and AKT pathways, which regulate proliferation and survival, are impaired. A transcriptomic study carried out in the Igf1-/- showed the altered expression of the cell cycle modulator Foxm1 and of the myocyte enhancer factor-2 (Mef2), a key factor for cellular differentiation, during inner ear development and early postnatal ages.IGF-1 haploinsufficiency has been also associated with growth retardation and HL in human genetic disorders such as Laron syndrome. In contrast, the Igf1+/- mouse does not show congenital HL, but adult mice hearing thresholds progressively increase with ageing and mice show increased susceptibility to noise insult. Adult Igf1+/- cochleae show unbalanced redox and inflammation biomarkers, as well as altered IGF-1 downstream signalling, which have been proposed as molecular mechanism underlying susceptibility. Mouse models of IGF-1 deficiency constitute a valuable tool to study the molecular bases of deafness and to identify potential targets to develop new HL therapies., This work was supported by grants from the Spanish MINECO/FEDER (SAF2014-53979-R and SAF2017-86107-R) and FP7-PEOPLE-2013-IAPP TARGEAR to IVN. SMC and LRdR holds a contract supported by CIBERER (Institute of Health Carlos III) co-financed with FEDER funds., Peer Reviewed

© 2019 by the authors., Cisplatin is a chemotherapeutic agent that causes the irreversible death of auditory sensory cells, leading to hearing loss. Local administration of cytoprotective drugs is a potentially better option co-therapy for cisplatin, but there are strong limitations due to the difficulty of accessing the inner ear. The use of nanocarriers for the efficient delivery of drugs to auditory cells is a novel approach for this problem. Solid lipid nanoparticles (SLNs) are biodegradable and biocompatible nanocarriers with low solubility in aqueous media. We show here that stearic acid-based SLNs have the adequate particle size, polydispersity index and ζ-potential, to be considered optimal nanocarriers for drug delivery. Stearic acid-based SLNs were loaded with the fluorescent probe rhodamine to show that they are efficiently incorporated by auditory HEI-OC1 (House Ear Institute-Organ of Corti 1) cells. SLNs were not ototoxic over a wide dose range. Glucocorticoids are used to decrease cisplatin-induced ototoxicity. Therefore, to test SLNs’ drug delivery efficiency, dexamethasone and hydrocortisone were tested either alone or loaded into SLNs and tested in a cisplatin-induced ototoxicity in vitro assay. Our results indicate that the encapsulation in SLNs increases the protective effect of low doses of hydrocortisone and lengthens the survival of HEI-OC1 cells treated with cisplatin., B.C. was supported by an MSC postdoctoral contract, FP7-PEOPLE2013-IAPP TARGEAR. This work was supported by grants MINECO/FEDER (SAF2017-86107-R) and Comunidad de Madrid/FEDER MULTITARGET&VIEW-CM (B2017/BMD-3688) to I.V.N. and ELKARTEK (2017 KK-2017/00008) to I.A., Peer reviewed

© 2019 Lassaletta, Calvino, Morales-Puebla, Lapunzina, Rodriguez-de la Rosa, Varela-Nieto and Martinez-Glez., Vestibular schwannomas (VSs) are benign tumors composed of differentiated neoplastic Schwann cells. They can be classified into two groups: sporadic VS and those associated with neurofibromatosis type 2 (NF2). VSs usually grow slowly, initially causing unilateral sensorineural hearing loss (HL) and tinnitus. These tumors cause HL both due to compression of the auditory nerve or the labyrinthine artery and due to the secretion of different substances potentially toxic to the inner ear or the cochlear nerve. As more and more patients are diagnosed and need to be managed, we are more than ever in need of searching for biomarkers associated with these tumors. Owing to an unknown toxic substance generated by the tumor, HL in VS may be linked to a high protein amount of perilymph. Previous studies have identified perilymph proteins correlated with tumor-associated HL, including μ-Crystallin (CRYM), low density lipoprotein receptor-related protein 2 (LRP2), immunoglobulin (Ig) γ-4 chain C region, Ig κ-chain C region, complement C3, and immunoglobulin heavy constant γ 3. Besides, the presence of specific subtypes of heat shock protein 70 has been suggested to be associated with preservation of residual hearing. It has been recently demonstrated that chemokine receptor-4 (CXCR4) is overexpressed in sporadic VS as well as in NF2 tumors and that hearing disability and CXCR4 expression may be correlated. Further, the genetic profile of VS and its relationship with poor hearing has also been studied, including DNA methylation, deregulated genes, growth factors, and NF2 gene mutations. The knowledge of biomarkers associated with VS would be of significant value to maximize outcomes of hearing preservation in these patients., This work was supported by a FEDER/Ministerio de Economía y Competitividad grant (SAF2017-86107-R) and by a Comunidad Autónoma de Madrid grant (B2017/BMD-3688).

Trabajo presentado en la XII Reunión Anual del CIBER de Enfermedades Raras, celebrada en San Lorenzo del Escorial (España) del 12 al 14 de marzo de 2019., La deficiencia en IGF-1 es una enfermedad rara (OMIM608747) que cursa con sordera neurosensorial y alteraciones neurológicas. El déficit de IGF-1 impide la correcta diferenciación neuronal en el ganglio auditivo del ratón y produce apoptosistemprana que progresa con la edad. Para facilitar el estudio de la deficiencia en IGF-1 y las alteraciones asociadas a la pérdida neuronal, se ha generado un modelo celular de la enfermedad humana en la línea de neuroblastoma murino Neuro2a mediante edición génica con CRISPR/Cas9. Dicho modelo reproduce la deleción parcial del exón 3 del gen Igf1 murino descrita como causante de pérdida auditiva en el hombre. Para la edición génica se transfectó el complejo crRNA:tracrRNA:Cas9 como ribonucleoproteína y se comprobó su incorporación en las células mediante microscopía detectando el tracrRNA marcado fluorescentemente. El ensayo de Surveyor detectó la presencia de mutaciones en las células, que se seleccionaron tras la clonación por dilución límite. La edición del gen Igf1 se comprobó por PCR en 56 clones y 5 de ellos se secuenciaron mediante el método Sanger. La secuenciación confirmó la deleción parcial de Igf1 en dos de los clones y se ha iniciado un estudio de su estado neuroinflamatorio, así como de su respuesta a distintos estímulos pro-inflamatorios, que puede contribuir a desvelar los mecanismos moleculares asociados a la deficiencia crónica de IGF-1., SAF2017 (86107-R); ACCI2016 (ER16P5AC7091); ACCI2017 (ER17P5AC7611/2017) y MouseAGE COST Action (BM1402)

Trabajo presentado en el 56th Inner Ear Biology Workshop, celebrado en Padua (Italia) del 7 al 10 de septiembre de 2019., In all vertebrates, the inner ear originates from the otic placode, an ectodermal patch in the head which invaginates and closes to form the otic vesicle (OV) or otocyst. The OV is considered the anlagen of the inner ear since their epithelial cells will differentiate generating most of the cell types building the complex structure of the adult inner ear. This transition is carried out by spatio-temporal restricted processes of proliferation, differentiation, migration, apoptosis, autophagy and senescence. A network of intracellular signals manages the precise process of development. The knowledge of the molecular bases that guide otic development is necessary for the design of novel treatments for the protection and repair of cells in hearing loss disorders.
One of the emerging family of compounds with critical roles in most cell biological processes are the bioactive sphingolipids. In fact the term ¿morphogenetic lipids¿ are coined for sphingolipids that regulate stem cells survival and differentiation during embryonic and postnatal development. Ceramide is the central backbone precursor of all complex bioactive sphingolipids. We had previously shown that a synthetic short-chain ceramide analogue was a potent inductor of apoptosis in OV cultures. The action of ceramide is finished by its phosphorylation to ceramide-1-phosphate (C1P), a reaction catalysed by the ceramide kinase (CERK). The presence of CERK has not been studied in the OV.
In the chicken embryo, Insulin-like growth factor-1 (IGF-1) is required for the survival and differentiation of the epithelial auditory precursors. In addition, IGF-1 deficit causes syndromic deafness in mice and men. In this work we have studied whether the pro-survival role of IGF-1 are due to the generation of C1P. To tackle the study we have used a specific CERK inhibitor (NVP-231). We have addressed the study in ex vivo cultures of OVs described as a good model of inner ear development that mimics the in vivo program maintaining the morphogenetic spatiotemporal pattern.
Our results show that CERK is expressed during the developing inner ear in chicken. The inhibition of CERK reduced proliferation and increased cell cycle arrest followed by cell death. The inhibition of CERK also altered the neurogenesis in the acoustic vestibular ganglion (AVG). Taken together, these results would confirm the involvement of C1P in the morphogenesis of the OV and AVG. The inhibitor counteracted the effect of IGF-1 exogenously added, suggesting that a part of the IGF-1 protective role could be carried out by CERK stimulation and C1P production., This work was supported by Spanish Ministerio de Economía, Industria y Competitividad (SAF2017-86107-R-FEDER) to MM and IVN.

Trabajo presentado en el 6th Symposium on Biomedical Research "Advances and Perspectives in Molecular Endocrinology", celebrado en Madrid (España) el 31 de mayo de 2019., Insulin-like growth factor-1 (IGF-1) is a key element in chicken otic development, and its deficit causes syndromic deafness in mice and men (1). Early steps of inner ear development involve the formation of an autonomous embryonic structure, the otic vesicle or otocyst. Otic vesicle development requires the coordinated actions of apoptosis, proliferation, senescence, cell differentiation and autophagy (2). Autophagy is a catabolic process essential for vertebrate development and homeostasis. We have reported that autophagy is required to facilitate the clearance of apoptotic cells and neuronal differentiation during early otic development (3). In other cellular context, IGF-1 has been shown to regulate autophagy (4). To better understand the molecular actions of IGF-1 and its potential modulation of autophagy in otic cells, we have used the cell line HEI-OC1 (derived from the auditory organ of the transgenic mouse Immortomouse¿) and ex vivo cultures of chicken otocysts. IGF-1 signaling pathway was studied by Western blotting of main IGF-1 targets. Proliferation was measured by incorporation of EdU. Apoptosis was assessed by TUNEL labelling and flow cytometry. Autophagy flux was analyzed by measuring LC3 and p62 relative protein levels. Our results show that IGF-1 promotes cell survival and cell proliferation while reduces cell death in both experimental models. IGF-1 is also playing a role in neuronal differentiation in the otic vesicle, maintaining otic neuroblasts in an undifferentiated and proliferative state. Furthermore IGF-1 actions include the downregulation of autophagy, which is induced in response to starvation and is essential for development and differentiation of otic cells., This work was supported by FEDER/SAF2017-86107-R-HEARCODE. SP holds an FPI predoctoral fellowship (BES-2015- 071311; European Social Fund/MINECO). AGM holds a MECD FPU fellowship (FPU16/03308). LR-R holds a contract supported by CIBERER (Institute of Health Carlos III) co-financed with FEDER funds

This work has been supported by Spanish MINECO/FEDER SAF2017-86107-R to IV-N and MM., Peer reviewed

Cellular senescence has classically been associated with aging. Intriguingly, recent studies have also unravelled key roles for senescence in embryonic development, regeneration, and reprogramming. Developmental senescence has been reported during embryonic development in different organisms and structures, such as the endolymphatic duct during inner ear development of mammals and birds. However, there is no study addressing the possible role of senescence on otic neurogenesis. TGFβ/SMAD is the best-known pathway linked to induction of developmental programmed cell senescence. Here, we studied if TGFβ2 induces cellular senescence during acoustic-vestibular-ganglion (AVG) formation. Using organotypic cultures of AVG, and characterizing different stages of otic neurogenesis in the presence of TGFβ2 and a selective TGF-β receptor type-I inhibitor, we show that TGFβ2 exerts a powerful action in inner ear neurogenesis but, contrary to what we recently observed during endolymphatic duct development, these actions are independent of cellular senescence. We show that TGFβ2 reduces proliferation, and induces differentiation and neuritogenesis of neuroblasts, without altering cell death. Our studies highlight the roles of TGFβ2 and cellular senescence in the precise regulation of cell fate within the developing inner ear and its different cell types, being their mechanisms of action highly cell-type dependent., This work has been supported by Spanish MINECO/FEDER SAF2017-86107-R to IV-N and MM., Peer reviewed

[Introduction]: Excessive exposure to noise is a common occurrence that contributes to approximately 50% of the non-genetic hearing loss cases. Researchers need to develop standardized preclinical models and identify molecular targets to effectively develop prevention and curative therapies., [Areas covered]: In this review, the authors discuss the many facets of human noise-induced pathology, and the primary experimental models for studying the basic mechanisms of noise-induced damage, making connections and inferences among basic science studies, preclinical proofs of concept and clinical trials., [Expert opinion]: Whilst experimental research in animal models has helped to unravel the mechanisms of noise-induced hearing loss, there are often methodological variations and conflicting results between animal and human studies which make it difficult to integrate data and translate basic outcomes to clinical practice. Standardization of exposure paradigms and application of -omic technologies will contribute to improving the effectiveness of transferring newly gained knowledge to clinical practice., This work was supported by the grants Multi Target and View FEDER/CM-B2017/BMD-3688 from the Consejería de Educación e Investigación, Comunidad de Madrid and MINECO/FEDER SAF2017-86107-R from the Ministerio de Economía, Industria y Competitividad, Gobierno de España., Peer reviewed

Resumen del trabajo presentado al 43rd Annual MidWinter Meeting-ARO, celebrado en San Jose, California (US) del 25 al 29 de enero de 2020., This work has been founded by Spanish MINECO/ FEDER SAF2017-86107-R to IVN. JMBM was supported by contracts from MINECO/FEDER SAF2014-AGEAR and MINECO/FEDER SAF2017-86107-R ., Peer reviewed

Resumen del trabajo presentado al 43rd Annual MidWinter Meeting-ARO, celebrado en San Jose, California (US) del 25 al 29 de enero de 2020., This work was supported by FEDER/SAF2017-86107-R-HEARCODE. SP holds an FPI predoctoral fellowship (BES-2015-071311; European Social Fund/MINECO). AGM holds a MECD FPU fellowship (FPU16/03308). LR-R holds a contract supported by CIBERER (Institute of Health Carlos III) co-financed with FEDER funds., Peer reviewed

Aging of the auditory system is associated with the incremental production of reactive oxygen species (ROS) and the accumulation of oxidative damage in macromolecules, which contributes to cellular malfunction, compromises cell viability, and, ultimately, leads to functional decline. Cellular detoxification relies in part on the production of NADPH, which is an important cofactor for major cellular antioxidant systems. NADPH is produced principally by the housekeeping enzyme glucose‐6‐phosphate dehydrogenase (G6PD), which catalyzes the rate‐limiting step in the pentose phosphate pathway. We show here that G6PD transgenic mice (G6PD‐Tg), which show enhanced constitutive G6PD activity and NADPH production along life, have lower auditory thresholds than wild‐type mice during aging, together with preserved inner hair cell (IHC) and outer hair cell (OHC), OHC innervation, and a conserved number of synapses per IHC. Gene expression of antioxidant enzymes was higher in 3‐month‐old G6PD‐Tg mice than in wild‐type counterparts, whereas the levels of pro‐apoptotic proteins were lower. Consequently, nitration of proteins, mitochondrial damage, and TUNEL+ apoptotic cells were all lower in 9‐month‐old G6PD‐Tg than in wild‐type counterparts. Unexpectedly, G6PD overexpression triggered low‐grade inflammation that was effectively resolved in young mice, as shown by the absence of cochlear cellular damage and macrophage infiltration. Our results lead us to propose that NADPH overproduction from an early stage is an efficient mechanism to maintain the balance between the production of ROS and cellular detoxification power along aging and thus prevents hearing loss progression., This work was funded by Multi Target and View FEDER/CM‐B2017/BMD‐3688 and MINECO/FEDER SAF2017‐86107‐R to IVN. JMBM was supported by a PhD CSIC contract., Peer reviewed

Resumen del trabajo presentado en el 43rd Annual MidWinter Meeting-ARO, celebrado en San José, California (Estados Unidos) del 25 al 29 de enero de 2020., Ageing of the auditory system is associated with the incremental production of reactive oxygen species (ROS) and the accumulation of oxidative-derived damage in macromolecules, which contribute to cellular malfunction, compromise cell viability and, finally, causes functional decline. The cellular detoxification power partially relies in NADPH production, which is a cofactor for major cellular antioxidant enzymes. NADPH is mainly produced by glucose-6-phosphate dehydrogenase (G6PD), an enzyme that catalyzes the rate-limiting step in the pentose phosphate pathway. We show here that the transgenic mouse G6PD-Tg, which shows enhanced NADPH production along life, maintains lower auditory thresholds than wild type mice during ageing. G6PD overexpression preserved inner (IHC) and outer hair cells (OHC), OHC innervation and number of synapses per IHC. Transcripts for antioxidant enzymes were increased whereas levels of pro-apoptotic proteins were reduced in 3-month-old G6PD-Tg. Consequently, nitration of proteins, mitochondrial damage and TUNEL+ apoptotic cells were reduced in 9-month-old G6PDTg compared to wild type mice. Unexpectedly, G6PD overexpression triggered low grade inflammation that was effectively resolved in young mice, as shown by the absence of cochlear cellular damage and macrophages infiltration. In conclusion, we propose here that NADPH overproduction from an early stage is an efficient mechanism to maintain the balance between the generation of ROS and the cell detoxification power along ageing and, therefore to prevent hearing loss progression., This work has been founded by Spanish MINECO/ FEDER SAF2017-86107-R to IVN. JMBM was supported by contracts from MINECO/FEDER SAF2014-AGEAR and MINECO/FEDER SAF2017-86107-R.

The raw data has been collected on each page, together with their statistical analysis for each figure., Sphingolipids are bioactive lipid components of cell membranes with important signal transduction functions in health and disease. Ceramide is the central building block for sphingolipid biosynthesis and is processed to form structurally and functionally distinct sphingolipids. Ceramide can be phosphorylated by ceramide kinase (CERK) to generate ceramide-1-phosphate, a cytoprotective signaling molecule that has been widely studied in multiple tissues and organs, including the developing otocyst. However, little is known about ceramide kinase regulation during inner ear development. Using chicken otocysts, we show that genes for CERK and other enzymes of ceramide metabolism are expressed during the early stages of inner ear development and that CERK is developmentally regulated at the otic vesicle stage. To explore its role in inner ear morphogenesis, we blocked CERK activity in organotypic cultures of otic vesicles with a specific inhibitor. Inhibition of CERK activity impaired proliferation and promoted apoptosis of epithelial otic progenitors. CERK inhibition also compromised neurogenesis of the acoustic-vestibular ganglion. Insulin-like growth factor-1 (IGF-1) is a key factor for proliferation, survival and differentiation in the chicken otocyst. CERK inhibition decreased IGF-1-induced AKT phosphorylation and blocked IGF-1-induced cell survival. Overall, our data suggest that CERK is activated as a central element in the network of anti-apoptotic pro-survival pathways elicited by IGF-1 during early inner ear development., This work was supported by the Spanish Ministerio de Economia y Competitividad, project FEDER/SAF2017-86107-R to IVN and MM., Peer reviewed

Sphingolipids are bioactive lipid components of cell membranes with important signal transduction functions in health and disease. Ceramide is the central building block for sphingolipid biosynthesis and is processed to form structurally and functionally distinct sphingolipids. Ceramide can be phosphorylated by ceramide kinase (CERK) to generate ceramide-1-phosphate, a cytoprotective signaling molecule that has been widely studied in multiple tissues and organs, including the developing otocyst. However, little is known about ceramide kinase regulation during inner ear development. Using chicken otocysts, we show that genes for CERK and other enzymes of ceramide metabolism are expressed during the early stages of inner ear development and that CERK is developmentally regulated at the otic vesicle stage. To explore its role in inner ear morphogenesis, we blocked CERK activity in organotypic cultures of otic vesicles with a specific inhibitor. Inhibition of CERK activity impaired proliferation and promoted apoptosis of epithelial otic progenitors. CERK inhibition also compromised neurogenesis of the acoustic-vestibular ganglion. Insulin-like growth factor-1 (IGF-1) is a key factor for proliferation, survival and differentiation in the chicken otocyst. CERK inhibition decreased IGF-1-induced AKT phosphorylation and blocked IGF-1-induced cell survival. Overall, our data suggest that CERK is activated as a central element in the network of anti-apoptotic pro-survival pathways elicited by IGF-1 during early inner ear development., This work was supported by the Spanish Ministerio de Economia y Competitividad, project FEDER/SAF2017-86107-R to IVN and MM., Peer reviewed

Multi Target and View FEDER/CM-B2017/BMD-3688; MINECO/FEDER SAF2017-86107-R., zip file containing 6 folders Bioanalyzer folder; Figure 1 folder [Figure1_qPCR.xlsx; Figure1_ABR.xlsx; Figure1_ Amplitudes_SPSS.pdf; Figure1_Audiogram_SPSS.pdf; Figure1_ Latencies_SPSS.pdf; Figure1_MyeP0 IHQ base.txt; Figure1_MyeP0 IHQ middle.txt; Figure1_MyeP0 IHQ quantification.xlsx]; Figure 2 folder [Figure2_CtBP2GluR2/3_ whole mount_quantification.xlsx; Figure2_Hair cells counts whole mount_quantification.xlsx; Figure2_Neurofilament number of fibers_quantification; Figure2_Neurofilament Intensity OHC_quantification.xlsx]; Figure 3 folder [Figure3_Western Blot_quantification analysis.xlsx; Exp0_p22phox Mb2 20170608_1327 Prec8sectif_AllLanes.pdf; Exp0_PI3K Mb2 20170608_1500 Prec8sectif_AllLanes.pdf; Exp1_p22phox_Mb4_20180222_1340_Prec2sec_tapandotif_AllLanes.pdf; Exp1_PI3K_Mb4_20180216_1446_Prec4sectif_AllLanes.pdf; Figure3_3NT IHQ quantification intensity; Figure3_Cyt C Oxidase IHF quantification intensity.xlsx; Figure3_qPCR Source Data.xlsx]; Figure 4 folder [Figure4_Western Blot_quantification analysis.xlsx; Figure4_Western Blot_ImageQuant; Figure4_TUNEL+ whole mount_quantification.xlsx]; Figure 5 folder [Figure5_qPCR .xlsx; Figure5_IBA1 IHF quantification]., Peer reviewed

© 2021 The Authors, Cis-diammine-dichloroplatinum[II] (cisplatin) is a potent and widely used chemotherapeutic agent with significant efficacy against several forms of cancer in adults and children. Unfortunately, cisplatin has multiple adverse effects and causes irreversible hearing loss (HL) in a large proportion of patients, which severely impacts their quality of life.1 Here, we confirm that treatment with LPT99, a small molecule inhibitor of the apoptosome, preserves hearing levels in a rat model of cisplatin-induced HL and prevents apoptosis in cisplatin-exposed HEI-OC1 cells. These data are encouraging and support the potential of LPT99 for the prevention of the secondary effects of cisplatin for HL., This work was supported by a SPIRALTHCIBERER ER17PE12 grant to SMC. SMC and LRR hold CIBERER contracts. BC, AMC, and JMB contracts were supported in part by projects from FP7-PEOPLE-2013-IAPP-TARGEAR and from MINECO/FEDER SAF2017- 86107-R to IVN.