AAV-mediated rescue of Eps8 expression in vivo restores hair-cell function in a mouse model of recessive deafness.

The transduction of acoustic information by hair cells depends upon mechanosensitive stereociliary bundles that project from their apical surface. Mutations or absence of the stereociliary protein EPS8 cause deafness in humans and mice, respectively. Eps8 knockout mice (Eps8 -/- ) have hair cells with immature stereocilia and fail to become sensory receptors. Here, we show that exogenous delivery of Eps8 using Anc80L65 in P1-P2 Eps8 -/- mice in vivo rescued the hair bundle structure of apical-coil hair cells. Rescued hair bundles correctly localize EPS8, WHIRLIN, MYO15, and BAIAP2L2, and generate normal mechanoelectrical transducer currents. Inner hair cells with normal-looking stereocilia re-expressed adult-like basolateral ion channels (BK and KCNQ4) and have normal exocytosis. The number of hair cells undergoing full recovery was not sufficient to rescue hearing in Eps8 -/- mice. Adeno-associated virus (AAV)-transduction of P3 apical-coil and P1-P2 basal-coil hair cells does not rescue hair cells, nor does Anc80L65-Eps8 delivery in adult Eps8 -/- mice. We propose that AAV-induced gene-base therapy is an efficient strategy to recover the complex hair-cell defects in Eps8 -/- mice. However, this therapeutic approach may need to be performed in utero since, at postnatal ages, Eps8 -/- hair cells appear to have matured or accumulated damage beyond the point of repair.

Human-specific gene CT47 blocks PRMT5 degradation to lead to meiosis arrest.

Exploring the functions of human-specific genes (HSGs) is challenging due to the lack of a tractable genetic model system. Testosterone is essential for maintaining human spermatogenesis and fertility, but the underlying mechanism is unclear. Here, we identified Cancer/Testis Antigen gene family 47 (CT47) as an essential regulator of human-specific spermatogenesis by stabilizing arginine methyltransferase 5 (PRMT5). A humanized mouse model revealed that CT47 functions to arrest spermatogenesis by interacting with and regulating CT47/PRMT5 accumulation in the nucleus during the leptotene/zygotene-to-pachytene transition of meiosis. We demonstrate that testosterone induces nuclear depletion of CT47/PRMT5 and rescues leptotene-arrested spermatocyte progression in humanized testes. Loss of CT47 in human embryonic stem cells (hESCs) by CRISPR/Cas9 led to an increase in haploid cells but blocked the testosterone-induced increase in haploid cells when hESCs were differentiated into haploid spermatogenic cells. Moreover, CT47 levels were decreased in nonobstructive azoospermia. Together, these results established CT47 as a crucial regulator of human spermatogenesis by preventing meiosis initiation before the testosterone surge.

Neuroplastin genetically interacts with Cadherin 23 and the encoded isoform Np55 is sufficient for cochlear hair cell function and hearing.

Mammalian hearing involves the mechanoelectrical transduction (MET) of sound-induced fluid waves in the cochlea. Essential to this process are the specialised sensory cochlear cells, the inner (IHCs) and outer hair cells (OHCs). While genetic hearing loss is highly heterogeneous, understanding the requirement of each gene will lead to a better understanding of the molecular basis of hearing and also to therapeutic opportunities for deafness. The Neuroplastin (Nptn) gene, which encodes two protein isoforms Np55 and Np65, is required for hearing, and homozygous loss-of-function mutations that affect both isoforms lead to profound deafness in mice. Here we have utilised several distinct mouse models to elaborate upon the spatial, temporal, and functional requirement of Nptn for hearing. While we demonstrate that both Np55 and Np65 are present in cochlear cells, characterisation of a Np65-specific mouse knockout shows normal hearing thresholds indicating that Np65 is functionally redundant for hearing. In contrast, we find that Nptn-knockout mice have significantly reduced maximal MET currents and MET channel open probabilities in mature OHCs, with both OHCs and IHCs also failing to develop fully mature basolateral currents. Furthermore, comparing the hearing thresholds and IHC synapse structure of Nptn-knockout mice with those of mice that lack Nptn only in IHCs and OHCs shows that the majority of the auditory deficit is explained by hair cell dysfunction, with abnormal afferent synapses contributing only a small proportion of the hearing loss. Finally, we show that continued expression of Neuroplastin in OHCs of adult mice is required for membrane localisation of Plasma Membrane Ca2+ ATPase 2 (PMCA2), which is essential for hearing function. Moreover, Nptn haploinsufficiency phenocopies Atp2b2 (encodes PMCA2) mutations, with heterozygous Nptn-knockout mice exhibiting hearing loss through genetic interaction with the Cdh23ahl allele. Together, our findings provide further insight to the functional requirement of Neuroplastin for mammalian hearing.

Long-term outcomes of perianal fistulizing Crohn's disease in the biologic era.

BACKGROUND AND AIM: While the advent of biologic therapy has led to improved outcomes in perianal fistulizing Crohn's disease (pfCD), loss of response is common. Previous studies suggest that patients who achieve radiological healing (with healing of underlying tracts on magnetic resonance imaging [MRI]) have a longer duration of response. The aim of this study was to characterize MRI outcomes of pfCD at a specialist inflammatory bowel disease (IBD) unit and compare the long-term clinical outcomes between patients achieving MRI and clinical healing. METHODS: A retrospective analysis of perianal fistulizing Crohn's patients treated at one specialist IBD unit was performed. Records were reviewed for patient demographics, disease history, clinical assessments, investigation results, and disease flares. Clinical remission was defined as closure of all baseline fistula openings. Radiological healing was defined as the absence of any T2-hyperintense sinuses, tracts, or collections. The primary end-point was rate of MRI healing. The secondary outcome was defined as flare-free period (time between clinical or radiological healing and patients' first signs/symptoms requiring therapy escalation). RESULTS: A total of 93 patients were included, with a median follow-up of 4.8 years (interquartile range, 2.4-6 years). Of 44 patients, 22 (50%) achieved clinical remission, while 15 of 93 (16%) achieved radiological healing. Of 22 patients, 10 (45%) with clinical remission had a subsequent disease flare (median time of 7 months) compared with 3 of 15 (20%) patients with MRI healing (median time of 3.6 years). Radiological healing was associated with a significantly longer flare-free period (P = 0.01). CONCLUSION: Radiological healing occurs less commonly but represents a deeper form of healing, associated with improved long-term clinical outcomes.

Joint ACPGBI and The Duke's Club statement on colonoscopy training.

Colorectal surgeons across the UK currently undertake a large proportion of routine diagnostic and therapeutic colonoscopy in most NHS Trusts [1]. Meanwhile, the new UK General Surgical curriculum now includes an indicative requirement of 200 diagnostic colonoscopies for surgical trainees who have declared a colorectal subspecialty interest (hereafter termed 'colorectal trainees'), indicating the JCST's (Joint Committee on Surgical Training) commitment to colonoscopy training. However, several studies have reported a marked deficiency in colonoscopy training opportunities and accreditation for surgical trainees compared with gastroenterology trainees [2-4].

Design, planning and implementation lessons learnt from a surgical multi-centre randomised controlled trial.

BACKGROUND: Increasingly, pragmatic randomised controlled trials are being used to evaluate surgical interventions, although they present particular difficulties in regards to recruitment and retention. METHODS: Procedures and processes related to implementation of a multi-centre pragmatic surgical randomised controlled trial are discussed. In this surgical trial, forecasting of consent rates based on similar trials and micro-costing of study activities with research partners were undertaken and a video was produced targeting recruiting staff with the aim of aiding recruitment. The baseline assessments were reviewed to ensure the timing did not impact on the outcome. Attrition due to procedure waiting time was monitored and data were triangulated for the primary outcome to ensure adequate follow-up data. RESULTS: Forecasting and costing ensured that the recruitment window was of adequate length and adequate resource was available for study procedures at multiple clinics in each hospital. Recruiting staff found the recruitment video useful. The comparison of patient-reported data collected prior to randomisation and prior to treatment provided confidence in the baseline data. Knowledge of participant dropout due to delays in treatment meant we were able to increase the recruitment target in a timely fashion, and along with the triangulation of data sources, this ensured adequate follow-up of randomised participants. CONCLUSIONS: This paper provides a range of evidence-based and experience-based approaches which, collectively, resulted in meeting our study objectives and from which lessons may be transferable. TRIAL REGISTRATION: ISRCTN, ISRCTN41394716 . Registered on 10 May 2012. UKCRN Study ID: 12486.

Patient-Reported Outcomes and Quality of Life after Treatment for Choroidal Melanoma.

BACKGROUND/AIMS: Patients with choroidal melanoma can develop psychological morbidity because of visual disability, pain, facial deformity, and fears of metastatic disease. The aim of this study was to report on the prevalence of symptoms, moods, and well-being after radiotherapy or enucleation for choroidal melanoma and how these outcomes changed over time. METHODS: Participants were mailed questionnaires approximately 6 months following treatment, then annually on every anniversary of their treatment. RESULTS: Soon after enucleation, patients experienced visual difficulties because of loss of stereopsis and visual field and were concerned about their appearance and about metastatic disease. After radiotherapy, patients were more concerned about local tumor recurrence and more troubled by diplopia and headache. Over time, visual difficulties diminished after enucleation but increased in patients who had received radiotherapy, with concerns about metastasis, loss of health, and tumor recurrence diminishing in both groups. Anxiety tended to diminish whereas depression increased, especially after enucleation. Emotional well-being improved after both kinds of treatment, whereas functional and physical well-being diminished after enucleation but improved after radiotherapy. Self-reported quality of life diminished equally with both kinds of treatment. CONCLUSION: The findings of this study should help physicians understand what patients tend to feel after treatment for choroidal melanoma.

Cellular Immune Response against Nontypeable Haemophilus influenzae Infecting the Preinflamed Middle Ear of the Junbo Mouse.

Nontypeable Haemophilus influenzae (NTHi) is a major pathogen causing acute otitis media (AOM). The pathology of AOM increases during long-term infection in the middle ear (ME), but the host cellular immune response to bacterial infection in this inflamed environment is poorly understood. Using the Junbo mouse, a characterized NTHi infection model, we analyzed the cellular response to NTHi infection in the Junbo mouse middle ear fluid (MEF). NTHi infection increased the total cell number and significantly decreased the proportion of live cells in the MEF at day 1, and this further decreased gradually on each day up to day 7. Flow cytometry analysis showed that neutrophils were the dominant immune cell population in the MEF and that NTHi infection significantly increased their proportion whereas it decreased the monocyte, macrophage, and dendritic cell proportions. Neutrophil and macrophage numbers increased in blood and spleen after NTHi infection. The T-cell population was dominated by T-helper (Th) cells in noninoculated MEF, and the effector Th (CD44+) cell population increased at day 2 of NTHi infection with an increase in IL-12p40 levels. Sustained NTHi infection up to 3 days increased the transforming growth factor ß levels, decreasing the effector cell population and increasing the T-regulatory (T-reg) cell population. In the preinflamed ME environment of the Junbo mouse, neutrophils are the first responder to NTHi infection followed by T-reg immune suppressive cells. These data indicate that sustained NTHi infection in the ME induces the immune suppressive response by inducing the T-reg cell population and reducing immune cell infiltration, thus promoting longer-term infection.

An N-Ethyl-N-Nitrosourea (ENU)-Induced Tyr265Stop Mutation of the DNA Polymerase Accessory Subunit Gamma 2 (Polg2) Is Associated With Renal Calcification in Mice.

Renal calcification (RCALC) resulting in nephrolithiasis and nephrocalcinosis, which affects ∼10% of adults by 70 years of age, involves environmental and genetic etiologies. Thus, nephrolithiasis and nephrocalcinosis occurs as an inherited disorder in ∼65% of patients, and may be associated with endocrine and metabolic disorders including: primary hyperparathyroidism, hypercalciuria, renal tubular acidosis, cystinuria, and hyperoxaluria. Investigations of families with nephrolithiasis and nephrocalcinosis have identified some causative genes, but further progress is limited as large families are unavailable for genetic studies. We therefore embarked on establishing mouse models for hereditary nephrolithiasis and nephrocalcinosis by performing abdominal X-rays to identify renal opacities in N-ethyl-N-nitrosourea (ENU)-mutagenized mice. This identified a mouse with RCALC inherited as an autosomal dominant trait, designated RCALC type 2 (RCALC2). Genomewide mapping located the Rcalc2 locus to a ∼16-Mbp region on chromosome 11D-E2 and whole-exome sequence analysis identified a heterozygous mutation in the DNA polymerase gamma-2, accessory subunit (Polg2) resulting in a nonsense mutation, Tyr265Stop (Y265X), which co-segregated with RCALC2. Kidneys of mutant mice (Polg2+/Y265X ) had lower POLG2 mRNA and protein expression, compared to wild-type littermates (Polg2+/+ ). The Polg2+/Y265X and Polg2+/+ mice had similar plasma concentrations of sodium, potassium, calcium, phosphate, chloride, urea, creatinine, glucose, and alkaline phosphatase activity; and similar urinary fractional excretion of calcium, phosphate, oxalate, and protein. Polg2 encodes the minor subunit of the mitochondrial DNA (mtDNA) polymerase and the mtDNA content in Polg2+/Y265X kidneys was reduced compared to Polg2+/+ mice, and cDNA expression profiling revealed differential expression of 26 genes involved in several biological processes including mitochondrial DNA function, apoptosis, and ubiquitination, the complement pathway, and inflammatory pathways. In addition, plasma of Polg2+/Y265X mice, compared to Polg2+/+ littermates had higher levels of reactive oxygen species. Thus, our studies have identified a mutant mouse model for inherited renal calcification associated with a Polg2 nonsense mutation. © 2018 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals, Inc.

A genetic modifier suggests that endurance exercise exacerbates Huntington's disease.

Polyglutamine expansions in the huntingtin gene cause Huntington's disease (HD). Huntingtin is ubiquitously expressed, leading to pathological alterations also in peripheral organs. Variations in the length of the polyglutamine tract explain up to 70% of the age-at-onset variance, with the rest of the variance attributed to genetic and environmental modifiers. To identify novel disease modifiers, we performed an unbiased mutagenesis screen on an HD mouse model, identifying a mutation in the skeletal muscle voltage-gated sodium channel (Scn4a, termed 'draggen' mutation) as a novel disease enhancer. Double mutant mice (HD; Scn4aDgn/+) had decreased survival, weight loss and muscle atrophy. Expression patterns show that the main tissue affected is skeletal muscle. Intriguingly, muscles from HD; Scn4aDgn/+ mice showed adaptive changes similar to those found in endurance exercise, including AMPK activation, fibre type switching and upregulation of mitochondrial biogenesis. Therefore, we evaluated the effects of endurance training on HD mice. Crucially, this training regime also led to detrimental effects on HD mice. Overall, these results reveal a novel role for skeletal muscle in modulating systemic HD pathogenesis, suggesting that some forms of physical exercise could be deleterious in neurodegeneration.

Patient-reported Outcomes and Quality of Life After Treatment of Choroidal Melanoma: A Comparison of Enucleation Versus Radiotherapy in 1596 Patients.

PURPOSE: To test the hypothesis that patients treated with radiotherapy for choroidal melanoma enjoy better quality of life (QoL) than patients who have undergone enucleation. METHODS: In this nonrandomized study, patients with choroidal melanoma treated at the Royal Liverpool University Hospital, Liverpool, UK, were invited to complete QoL questionnaires approximately 6 months postoperatively and then on each anniversary of their primary treatment. These instruments consisted of the European Organization for Research and Treatment of Cancer (EORTC) QLQ-OPT30 questionnaire, Hospital Anxiety & Depression Scale, and the Functional Assessment of Cancer Treatment questionnaire. Patient-reported outcomes were correlated with demographics, ocular treatment, social factors, presenting tumor and ocular status, self-reported general health, marital status, and employment status. RESULTS: The 1596 patients were treated with radiotherapy (72.3%) or enucleation (27.7%). Enucleation was associated with male sex (χ2, P = .004), older age (t test, P < .001), larger tumor diameter (t test, P < .001), monosomy 3 (χ2, P < .001), depression (linear regression, 95% confidence interval [CI], .17 to 1.01), and reduced physical and functional well-being (linear regression, 95% CI, -1.14 to -0.12 and -1.96 to -0.47), respectively. Poor QoL was attributed to the ocular disease by 21% and 20% of enucleated and irradiated patients, respectively (χ2, P = .938). CONCLUSIONS: Patient-reported outcomes and QoL were worse in patients who had undergone primary enucleation for choroidal melanoma. These outcomes may partly have been caused by factors predisposing to enucleation rather than enucleation itself, because enucleated patients tended to be older, with more advanced disease at presentation, and a worse prognosis for survival. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

A mouse-to-man candidate gene study identifies association of chronic otitis media with the loci TGIF1 and FBXO11.

Chronic otitis media with effusion (COME) is the most common cause of hearing loss in children, and known to have high heritability. Mutant mouse models have identified Fbxo11, Evi1, Tgif1, and Nisch as potential risk loci. We recruited children aged 10 and under undergoing surgical treatment for COME from 35 hospitals in the UK, and their nuclear family. We performed association testing with the loci FBXO11, EVI1, TGIF1 and NISCH and sought to replicate significant results in a case-control cohort from Finland. We tested 1296 families (3828 individuals), and found strength of association with the T allele at rs881835 (p = 0.006, OR 1.39) and the G allele at rs1962914 (p = 0.007, OR 1.58) at TGIF1, and the A allele at rs10490302 (p = 0.016, OR 1.17) and the G allele at rs2537742 (p = 0.038, OR 1.16) at FBXO11. Results were not replicated. This study supports smaller studies that have also suggested association of otitis media with polymorphism at FBX011, but this is the first study to report association with the locus TGIF1. Both FBX011 and TGIF1 are involved in TGF-ß signalling, suggesting this pathway may be important in the transition from acute to chronic middle ear inflammation, and a potential molecular target.

A mutation in Nischarin causes otitis media via LIMK1 and NF-κB pathways.

Otitis media (OM), inflammation of the middle ear (ME), is a common cause of conductive hearing impairment. Despite the importance of the disease, the aetiology of chronic and recurrent forms of middle ear inflammatory disease remains poorly understood. Studies of the human population suggest that there is a significant genetic component predisposing to the development of chronic OM, although the underlying genes are largely unknown. Using N-ethyl-N-nitrosourea mutagenesis we identified a recessive mouse mutant, edison, that spontaneously develops a conductive hearing loss due to chronic OM. The causal mutation was identified as a missense change, L972P, in the Nischarin (NISCH) gene. edison mice develop a serous or granulocytic effusion, increasingly macrophage and neutrophil rich with age, along with a thickened, inflamed mucoperiosteum. We also identified a second hypomorphic allele, V33A, with only modest increases in auditory thresholds and reduced incidence of OM. NISCH interacts with several proteins, including ITGA5 that is thought to have a role in modulating VEGF-induced angiogenesis and vascularization. We identified a significant genetic interaction between Nisch and Itga5; mice heterozygous for Itga5-null and homozygous for edison mutations display a significantly increased penetrance and severity of chronic OM. In order to understand the pathological mechanisms underlying the OM phenotype, we studied interacting partners to NISCH along with downstream signalling molecules in the middle ear epithelia of edison mouse. Our analysis implicates PAK1 and RAC1, and downstream signalling in LIMK1 and NF-κB pathways in the development of chronic OM.

Panel 3: Genetics and Precision Medicine of Otitis Media.

Objective The objective is to perform a comprehensive review of the literature up to 2015 on the genetics and precision medicine relevant to otitis media. Data Sources PubMed database of the National Library of Medicine. Review Methods Two subpanels were formed comprising experts in the genetics and precision medicine of otitis media. Each of the panels reviewed the literature in their respective fields and wrote draft reviews. The reviews were shared with all panel members, and a merged draft was created. The entire panel met at the 18th International Symposium on Recent Advances in Otitis Media in June 2015 and discussed the review and refined the content. A final draft was made, circulated, and approved by the panel members. Conclusion Many genes relevant to otitis media have been identified in the last 4 years in advancing our knowledge regarding the predisposition of the middle ear mucosa to commensals and pathogens. Advances include mutant animal models and clinical studies. Many signaling pathways are involved in the predisposition of otitis media. Implications for Practice New knowledge on the genetic background relevant to otitis media forms a basis of novel potential interventions, including potential new ways to treat otitis media.

Is social inequality related to different patient concerns in routine oral cancer follow-up clinics?

Oral cancer has a higher incidence in the lower social strata, and these patients are less likely to engage in supportive interventions and report a poorer quality of life (QoL). The aim of this paper is to compare the Patient Concerns Inventory (PCI) responses across social groups attending routine oral cancer follow-up clinics with particular focus on the deprivation lower quartile. The PCI package is completed by patients as part of their routine review consultation with SNR. Patients were those diagnosed between 2008 and 2012. Deprivation was stratified using the IMD 2010 from postcode. Of the 106 eligible patients, 85 % used the PCI. Just over half (54 %) were living in the most deprived quartile, with two-thirds (68 %) of males in the most deprived quartile, compared with 35 % of females (p = 0.004). In regard to number and type of PCI items selected by patients at their first PCI clinic, there were no notable differences in respect of IMD classification. The two commonest concerns were fear of recurrence (43 %) and sore mouth (43 %). The most deprived quartile reported significant problems in regard to mood (p = 0.004) and recreation (p = 0.02), and a non-significant trend (36 vs 18 %, p = 0.09) in stating their overall QoL as being less than good. It is possible to identify the concerns of patients from lower socioeconomic strata as part of routine follow-up clinics. This allows for targeted multi-professional intervention and supports to improve the outcome in this hard to reach group.

An in vitro model of murine middle ear epithelium.

Otitis media (OM), or middle ear inflammation, is the most common paediatric disease and leads to significant morbidity. Although understanding of underlying disease mechanisms is hampered by complex pathophysiology it is clear that epithelial abnormalities underpin the disease. There is currently a lack of a well-characterised in vitro model of the middle ear (ME) epithelium that replicates the complex cellular composition of the middle ear. Here, we report the development of a novel in vitro model of mouse middle ear epithelial cells (mMECs) at an air-liquid interface (ALI) that recapitulates the characteristics of the native murine ME epithelium. We demonstrate that mMECs undergo differentiation into the varied cell populations seen within the native middle ear. Proteomic analysis confirmed that the cultures secrete a multitude of innate defence proteins from their apical surface. We showed that the mMECs supported the growth of the otopathogen, nontypeable Haemophilus influenzae (NTHi), suggesting that the model can be successfully utilised to study host-pathogen interactions in the middle ear. Overall, our mMEC culture system can help to better understand the cell biology of the middle ear and improve our understanding of the pathophysiology of OM. The model also has the potential to serve as a platform for validation of treatments designed to reverse aspects of epithelial remodelling that underpin OM development.

Mouse Models of NMNAT1-Leber Congenital Amaurosis (LCA9) Recapitulate Key Features of the Human Disease.

The nicotinamide nucleotide adenylyltransferase 1 (NMNAT1) enzyme is essential for regenerating the nuclear pool of NAD(+) in all nucleated cells in the body, and mounting evidence also suggests that it has a separate role in neuroprotection. Recently, mutations in the NMNAT1 gene were associated with Leber congenital amaurosis, a severe retinal degenerative disease that causes blindness during infancy. Availability of a reliable mammalian model of NMNAT1-Leber congenital amaurosis would assist in determining the mechanisms through which disruptions in NMNAT1 lead to retinal cell degeneration and would provide a resource for testing treatment options. To this end, we identified two separate N-ethyl-N-nitrosourea-generated mouse lines that harbor either a p.V9M or a p.D243G mutation. Both mouse models recapitulate key aspects of the human disease and confirm the pathogenicity of mutant NMNAT1. Homozygous Nmnat1 mutant mice develop a rapidly progressing chorioretinal disease that begins with photoreceptor degeneration and includes attenuation of the retinal vasculature, optic atrophy, and retinal pigment epithelium loss. Retinal function deteriorates in both mouse lines, and, in the more rapidly progressing homozygous Nmnat1(V9M) mutant mice, the electroretinogram becomes undetectable and the pupillary light response weakens. These mouse models offer an opportunity for investigating the cellular mechanisms underlying disease pathogenesis, evaluating potential therapies for NMNAT1-Leber congenital amaurosis, and conducting in situ studies on NMNAT1 function and NAD(+) metabolism.

Interactions between the otitis media gene, Fbxo11, and p53 in the mouse embryonic lung.

Otitis media with effusion (OME) is the most common cause of hearing loss in children, and tympanostomy (ear tube insertion) to alleviate the condition remains the commonest surgical intervention in children in the developed world. Chronic and recurrent forms of otitis media (OM) are known to have a very substantial genetic component; however, until recently, little was known of the underlying genes involved. The Jeff mouse mutant carries a mutation in the Fbxo11 gene, a member of the F-box family, and develops deafness due to a chronic proliferative OM. We previously reported that Fbxo11 is involved in the regulation of transforming growth factor beta (TGF-ß) signalling by regulating the levels of phospho-Smad2 in the epithelial cells of palatal shelves, eyelids and airways of the lungs. It has been proposed that FBXO11 regulates the cell's response to TGF-ß through the ubiquitination of CDT2. Additional substrates for FBXO11 have been identified, including p53. Here, we have studied both the genetic and biochemical interactions between FBXO11 and p53 in order to better understand the function of FBXO11 in epithelial development and its potential role in OM. In mice, we show that p53 (also known as Tp53) homozygous mutants and double heterozygous mutants (Jf/+ p53/+) exhibit similar epithelial developmental defects to Fbxo11 homozygotes. FBXO11 and p53 interact in the embryonic lung, and mutation in Fbxo11 prevents the interaction with p53. Both p53 and double mutants show raised levels of pSMAD2, recapitulating that seen in Fbxo11 homozygotes. Overall, our results support the conclusion that FBXO11 regulates the TGF-ß pathway in the embryonic lung via cross-talk with p53.

N-ethyl-N-Nitrosourea (ENU) induced mutations within the klotho gene lead to ectopic calcification and reduced lifespan in mouse models.

Ectopic calcification (EC), which is the pathological deposition of calcium and phosphate in extra-skeletal tissues, may be associated with hypercalcaemic and hyperphosphataemic disorders, or it may occur in the absence of metabolic abnormalities. In addition, EC may be inherited as part of several monogenic disorders and studies of these have provided valuable insights into the metabolic pathways regulating mineral metabolism. For example, studies of tumoural calcinosis, a disorder characterised by hyperphosphataemia and progressive EC, have revealed mutations of fibroblast growth factor 23 (FGF23), polypeptide N-acetyl galactosaminyltransferase 3 (GALNT3) and klotho (KL), which are all part of a phosphate-regulating pathway. However, such studies in humans are limited by the lack of available large families with EC, and to facilitate such studies we assessed the progeny of mice treated with the chemical mutagen N-ethyl-N-nitrosourea (ENU) for EC. This identified two mutants with autosomal recessive forms of EC, and reduced lifespan, designated Ecalc1 and Ecalc2. Genetic mapping localized the Ecalc1 and Ecalc2 loci to a 11.0 Mb region on chromosome 5 that contained the klotho gene (Kl), and DNA sequence analysis identified nonsense (Gln203Stop) and missense (Ile604Asn) Kl mutations in Ecalc1 and Ecalc2 mice, respectively. The Gln203Stop mutation, located in KL1 domain, was severely hypomorphic and led to a 17-fold reduction of renal Kl expression. The Ile604Asn mutation, located in KL2 domain, was predicted to impair klotho protein stability and in vitro expression studies in COS-7 cells revealed endoplasmic reticulum retention of the Ile604Asn mutant. Further phenotype studies undertaken in Ecalc1 (kl203X/203X) mice demonstrated elevations in plasma concentrations of phosphate, FGF23 and 1,25-dihydroxyvitamin D. Thus, two allelic variants of Kl that develop EC and represent mouse models for tumoural calcinosis have been established.