How research institutions can foster innovation.

Carrying out research means being innovative, which requires novelty. Novelty is an important source of scientific breakthroughs and has great technological impact. Research institutions stand to benefit from fostering innovation. Here, we outline what academic institutions can do to help their scientists become more innovative.

The Role of Deregulated MicroRNAs in Age-Related Macular Degeneration Pathology.

Purpose: We previously identified three microRNAs (miRNAs) with significantly increased expression in the serum of patients with age-related macular degeneration (AMD) compared with healthy controls. Our objective was to identify potential functional roles of these upregulated miRNAs (miR-19a, miR-126, and miR-410) in AMD, using computational tools for miRNAs prediction and identification, and to demonstrate the miRNAs target genes and signaling pathways. We also aim to demonstrate the pathologic role of isolated sera-derived exosomes from patients with AMD and controls using in vitro models. Methods: miR-19a, miR-126, and miR-410 were investigated using bioinformatic approaches, including DIANA-mirPath and miR TarBase. Data on the resulting target genes and signaling pathways were incorporated with the differentially expressed miRNAs in AMD. Apoptosis markers, human apoptosis miRNAs polymerase chain reaction arrays and angiogenesis/vasculogenesis assays were performed by adding serum-isolated AMD patient or control patient derived exosomes into an in vitro human angiogenesis model and ARPE-19 cell lines. Results: A number of pathways known to be involved in AMD development and progression were predicted, including the vascular endothelial growth factor signaling, apoptosis, and neurodegenerative pathways. The study also provides supporting evidence for the involvement of serum-isolated AMD-derived exosomes in the pathology of AMD, via apoptosis and/or angiogenesis. Conclusions: miR-19a, miR-126, miR-410 and their target genes had a significant correlation with AMD pathogenesis. As such, they could be potential new targets as predictive biomarkers or therapies for patients with AMD. Translational Relevance: The functional analysis and the pathologic role of altered miRNA expression in AMD may be applicable in developing new therapies for AMD through the disruption of individual or multiple pathophysiologic pathways.

Identification of Novel Serum MicroRNAs in Age-Related Macular Degeneration.

Purpose: To identify circulating microRNAs (miRNA) associated with age-related macular degeneration (AMD). Thus differentially expressed serum miRNA could be used as AMD biomarkers. Methods: This study involved total RNA isolation from sera from patients with atrophic AMD (n = 10), neovascular AMD (n = 10), and age- and sex-matched controls (n = 10). A total of 377 miRNAs were coanalyzed using array technologies, and differentially regulated miRNAs were determined. Extensive validation studies (n = 90) of serum from AMD patients and controls confirmed initial results. Total RNA isolation was carried out from sera from patients with atrophic AMD (n = 30), neovascular AMD (n = 30), and controls (n = 30). Fourteen miRNAs from the discovery dataset were coanalyzed using quantitative real-time polymerase chain reaction (qRT-PCR) to validate their presence. Results: Unsupervised hierarchical clustering indicated that AMD serum specimens have a different miRNA profile to healthy controls. We successfully identified and validated the differentially regulated miRNAs in serum from AMD patients versus controls. The biomarker potential of three miRNAs (miR-126, miR-19a, and miR-410) was confirmed by qRT-PCR, with significantly increased quantities in serum of AMD patients compared with healthy controls. Conclusions: Increased quantities of miR-126, miR-410, and miR-19a in serum from AMD patients indicate that these miRNAs could potentially serve as diagnostic AMD biomarkers. All three miRNAs significantly correlated with AMD pathogenesis. Translational Relevance: The discovery of new AMD miRNA may act as biomarkers in evaluating AMD diagnosis and prognosis.

How dentists learn behaviour support skills for adults with intellectual developmental disorders: A qualitative analysis.

INTRODUCTION: An understanding of how dentists develop patient support techniques for use with adults with intellectual developmental disorders (IDD) may lead to a better understanding of how these techniques can be taught. In this study, we explored how skilled dentists developed non-physical, non-pharmacological patient support techniques (nPSTs) for use with adults with IDD. MATERIALS AND METHODS: Adopting a qualitative descriptive design, a synchronous online group interview was undertaken with six dentists. Informants were subsequently contacted in pairs, or individually, for further interview. All data were analysed using thematic content analysis. Author biases and rigour are considered. RESULTS: Three categories emerged: Motivation to learn; Formal learning; and Informal learning, and the latter had three subcategories: Observation; Trial; and error and Experience. Motivators to learn PST skills included perceived empathy and a sense of responsibility towards patients with IDD. Formal undergraduate learning was lacking leaving dentists to rely on paediatric training "A paediatric model from your training… needs to be restructured and re-emphasised with people with disabilities as they progress through the lifespan.", whereas specialist training was reported to be helpful where available. Over time, practitioners developed an individualised skillset through observation, trial and error and experience. "You learn. Just like any job, you learn on the job. You learn a lot from experience and mistakes." DISCUSSION: Essential patient support skills appear to be acquired in an ad hoc manner. How dentists learn their skills has implications for dental training for future and current dental professionals. CONCLUSIONS: Specific recommendations to improve education are made.

Interdisciplinary Communication Needs to Become a Core Scientific Skill.

As scientific research has advanced so too has the complexity of the questions addressed. Cross-disciplinary collaborations are often the most efficient route to managing that complexity and require effective communication across boundaries. To continue driving science forward and be able to tackle global challenges, the art of good interdisciplinary communication needs to become a core skill in a scientist's portfolio.

Risk factors and biomarkers of age-related macular degeneration.

A biomarker can be a substance or structure measured in body parts, fluids or products that can affect or predict disease incidence. As age-related macular degeneration (AMD) is the leading cause of blindness in the developed world, much research and effort has been invested in the identification of different biomarkers to predict disease incidence, identify at risk individuals, elucidate causative pathophysiological etiologies, guide screening, monitoring and treatment parameters, and predict disease outcomes. To date, a host of genetic, environmental, proteomic, and cellular targets have been identified as both risk factors and potential biomarkers for AMD. Despite this, their use has been confined to research settings and has not yet crossed into the clinical arena. A greater understanding of these factors and their use as potential biomarkers for AMD can guide future research and clinical practice. This article will discuss known risk factors and novel, potential biomarkers of AMD in addition to their application in both academic and clinical settings.

Survivin expression is associated with lens epithelial cell proliferation and fiber cell differentiation.

PURPOSE: Survivin (Birc5) is the smallest member of the inhibitor of apoptosis (IAP) protein family, which regulates the cell cycle/apoptosis balance. The purpose of this study was to examine Survivin expression in the embryonic chick lens, in chick lens epithelial cell cultures, and in the postnatal mouse lens. METHODS: Survivin expression was examined using a combination of quantitative real-time polymerase chain reaction, western blotting, and immunocytochemistry. To correlate Survivin expression with the timing of proliferation, we determined the profile of cell proliferation in the developing lens using the cell cycle marker proliferating cell nuclear antigen (PCNA) in quantitative western blotting and immunocytochemistry studies. We also examined the expression of PCNA and the extent of denucleation using terminal deoxynucleotidyl transferase (TdT)-mediated biotin-dUTP nick-end labeling (TUNEL) of lentoids (lens fiber-like cells) during chick lens epithelial cell differentiation in vitro. RESULTS: At embryonic day (ED) 4, Survivin immunostaining was present in two pools in lens epithelial cells and fiber cells: cytoplasmic and nuclear. The nuclear staining became more pronounced as the lens epithelial cells differentiated into lens fiber cells. At ED12, Survivin staining was observed in lens fiber cell nuclei containing marginalized chromatin, indicative of early denucleation events. Using western blotting, Survivin expression peaked at ED6, diminishing thereafter. This profile of expression correlated with the events in chick lens epithelial cell cultures: i) increased Survivin expression was associated with an increase in PCNA staining up to day 6 of culture and ii) downregulation of Survivin expression at day 8 of culture was coincident with a dramatic decrease in PCNA staining and an increase in TdT-mediated biotin-dUTP nick-end labeling in lentoids. In early postnatal mouse lenses, Survivin and PCNA were highly expressed and decreased thereafter during postnatal lens maturation. CONCLUSIONS: Survivin is expressed during chick and mouse lens development and in chick lens epithelial cell cultures. High levels of Survivin expression correlated with high rates of proliferation of lens epithelial cells at early stages of development. Downregulation of Survivin expression with development and its progressive localization to the nuclei of lens fiber cells was coincident with a decrease in cell proliferation and increased denucleation in differentiating lens fiber cells. These studies suggest an important role for Survivin as a dual regulator of lens epithelial cell proliferation and lens fiber cell differentiation.

Mitochondrial localization and ocular expression of mutant Opa3 in a mouse model of 3-methylglutaconicaciduria type III.

PURPOSE: To investigate the developmental and ocular expression of Opa3 in a mouse model of 3-methylglutaconicaciduria type III and the effect of mutation on protein localization and mitochondrial morphology. METHODS: The B6 C3-Opa3(L122P) mouse carrying a missense mutation in exon 2 (c.365T>C; p.L122P) of Opa3, which displays features of recessive 3-methylglutaconic aciduria type III was studied. The expression of Opa3 was determined with RT-PCR, quantitative PCR, and Western blot, in embryos (embryonic day [E]8 to postnatal day [P]0) and adult tissues, and by ocular immunohistochemistry. Mitochondria were stained using a mitochondrion-selective probe in mouse embryonic fibroblasts from Opa3(-/-) mutants and imaged by electron microscopy of the retinas. RESULTS: The splice variants Opa3a and Opa3b were expressed in the lenses and the retinas in the Opa3(-/-) mice, with the expression of the Opa3a isoform predominant. Opa3 was expressed throughout embryonic development, with high levels of expression in the developing brain, retina, optic nerve, and lens. Opa3 localized to the mitochondria, and the L122P mutant protein did not mislocalize. Neither protein localized to the peroxisome. Opa3(-/-) mice displayed disrupted mitochondrial morphology in the retina. Wild-type Opa3 protein increased as the lenses aged, despite the reduction in Opa3 mRNA occurring as a part of lens differentiation. However, mutant Opa3 mRNA was upregulated in homozygous mutant lenses, suggesting a compensatory increase in expression, which may further increase Opa3 protein levels. CONCLUSIONS: Mutant Opa3 protein retains its mitochondrial localization and induces disrupted mitochondrial morphology. Opa3 accumulates in the lens. The results may reflect a slow turnover of Opa3 protein in vivo and may be important in normal lens physiology.

The ocular lens: a classic model for development, physiology and disease.

Millions are rendered blind or exhibit visual impairment due to pathologies of the lens of the eye. Lens research therefore addresses the direct need to gain insights into the cellular and molecular basis of disease, but, moreover, serves as a valuable experimental system to answer fundamental biological questions. This themed issue showcases the scientific knowledge of the processes involved in the development, structure, ultrastructure, physiology and pathology of the lens and how this information has the potential to significantly further knowledge in various fields of research. The issue is divided into three main areas. Firstly, the lens is discussed as a developmental model for embryonic induction, as an elegant system for studying the role of growth factors in development, and for analysis of the molecular control and cellular basis of cellular differentiation. The genetic basis of disorders of lens development, including paediatric cataract (lens opacity), are also discussed in this section. Secondly, adult lens structure and ultrastructure are covered, as well as the lens as a model for homeostasis and solute exchange. Finally, the papers in the latter part of the special issue review lens pathology, including the lens as a model for normal and pathological ageing, vitreoretinal influences on lens function and cataract and the lens as a model for fibrotic disease. Overall, the articles highlight the lens as a continuing, very important and attractive model system for biologists working in many different research areas.

Lens fibre cell differentiation and organelle loss: many paths lead to clarity.

The programmed removal of organelles from differentiating lens fibre cells contributes towards lens transparency through formation of an organelle-free zone (OFZ). Disruptions in OFZ formation are accompanied by the persistence of organelles in lens fibre cells and can contribute towards cataract. A great deal of work has gone into elucidating the nature of the mechanisms and signalling pathways involved. It is apparent that multiple, parallel and redundant pathways are involved in this process and that these pathways form interacting networks. Furthermore, it is possible that the pathways can functionally compensate for each other, for example in mouse knockout studies. This makes sense given the importance of lens clarity in an evolutionary context. Apoptosis signalling and proteolytic pathways have been implicated in both lens fibre cell differentiation and organelle loss, including the Bcl-2 and inhibitor of apoptosis families, tumour necrosis factors, p53 and its regulators (such as Mdm2) and proteolytic enzymes, including caspases, cathepsins, calpains and the ubiquitin-proteasome pathway. Ongoing approaches being used to dissect the molecular pathways involved, such as transgenics, lens-specific gene deletion and zebrafish mutants, are discussed here. Finally, some of the remaining unresolved issues and potential areas for future studies are highlighted.

Zebrafish: an exciting model for investigating the spatio-temporal pattern of enteric nervous system development.

AIM: Recently, the zebrafish (Danio rerio) has been shown to be an excellent model for human paediatric research. Advantages over other models include its small size, externally visually accessible development and ease of experimental manipulation. The enteric nervous system (ENS) consists of neurons and enteric glia. Glial cells permit cell bodies and processes of neurons to be arranged and maintained in a proper spatial arrangement, and are essential in the maintenance of basic physiological functions of neurons. Glial fibrillary acidic protein (GFAP) is expressed in astrocytes, but also expressed outside of the central nervous system. The aim of this study was to investigate the spatio-temporal pattern of GFAP expression in developing zebrafish ENS from 24 h post-fertilization (hpf), using transgenic fish that express green fluorescent protein (GFP). METHODS: Zebrafish embryos were collected from transgenic GFP Tg(GFAP:GFP)(mi2001) adult zebrafish from 24 to 120 hpf, fixed and processed for whole mount immunohistochemistry. Antibodies to Phox2b were used to identify enteric neurons. Specimens were mounted on slides and imaging was performed using a fluorescent laser confocal microscope. RESULTS: GFAP:GFP labelling outside the spinal cord was identified in embryos from 48 hpf. The patterning was intracellular and consisted of elongated profiles that appeared to migrate away from the spinal cord into the periphery. At 72 and 96 hpf, GFAP:GFP was expressed dorsally and ventrally to the intestinal tract. At 120 hpf, GFAP:GFP was expressed throughout the intestinal wall, and clusters of enteric neurons were identified using Phox2b immunofluorescence along the pathway of GFAP:GFP positive processes, indicative of a migratory pathway of ENS precursors from the spinal cord into the intestine. CONCLUSION: The pattern of migration of GFAP:GFP expressing cells outside the spinal cord suggests an organized, early developing migratory pathway to the ENS. This shows for the first time that Tg(GFAP:GFP)(mi2001) zebrafish model is an ideal one to study spatio-temporal patterning of early ENS development.

Cellular inhibitor of apoptosis (cIAP1) is down-regulated during retinal ganglion cell (RGC) maturation.

Apoptosis, is the main type of cell death that occurs in ageing and neurodegenerative disease, such as glaucoma. This study therefore characterises the expression profile of caspases (pro-apoptosis) and inhibitors of apoptosis (IAPs; anti-apoptosis) during maturation of the Brown Norway rat retina between 6 weeks and >24 weeks and also examines concomitant changes in expression of tumor necrosis factor receptor associated factor 2 (TRAF2). The expression profiles of caspases (initiator caspases 8, 9 and effector caspases 6, 7, 3) and inhibitors of apoptosis (IAPs) (Neuronal IAP), cellular IAP1 and 2 (cIAP1/2), X-chromosome linked IAP (XIAP), Survivin, Bruce and Livin) were examined in retinae from 6 weeks and >24 weeks old BN rats using semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), real-time PCR, Western blotting and immunofluoroscence analysis. Caspase expression was not altered significantly during the study interval. IAP expression showed a general reduction during maturation of BN retina, which was statistically significant for cIAP1. cIAP1 reduction was confirmed by Western blotting and immunoflouroscence and was restricted to cells in the retinal ganglion cell layer (RGCL). Accumulation of TRAF2 was observed in the RGCL accompanying the down-regulation of cIAP1 observed. Our results suggest that cells in the mature RGCL may have a greater susceptibility to cell death compared to their younger counterparts and this may be due in part to a reduction in activation of survival pathways involving IAPs and TRAFs.

Retinal ganglion cell death postponed: giving apoptosis a break?

Glaucoma is characterised by the preferential death of retinal ganglion cells (RGCs). However, mammalian models indicate that neurons pass through a period in which they manifest signs of neuronal damage, but have yet to fully commit to death. Mounting evidence suggests that one of the clearest indications of this process is the reduction in RGC dendritic arborisation, resulting in functional compromise. The extent to which this may be reversible is unclear, since the molecular events that precede changes in dendritic structure have received little attention. Furthermore, there are likely to be many factors involved in this process potentially acting in different individual cells at different times. Recent work in Drosophila shows that dendritic reorganisation/remodelling involves local activation and tight regulation of caspase activity. Here, we propose a model in which the balance between caspases and inhibitors of apoptosis (IAPs) contributes towards the regulation of dendritic remodelling. Thus, RGC dendrite reorganisation and cell death represent opposite ends of a spectrum of events regulated by apoptosis signalling pathways. We summarise relevant events in apoptosis, focusing on caspases and IAPs. We also discuss mechanisms of dendrite development, structure and reorganisation and the implications for early diagnosis and treatment of glaucoma and neurodegenerative disease.

3-Dimensional modelling of chick embryo eye development and growth using high resolution magnetic resonance imaging.

Magnetic resonance imaging (MRI) is a powerful tool for generating 3-dimensional structural and functional image data. MRI has already proven valuable in creating atlases of mouse and quail development. Here, we have exploited high resolution MRI to determine the parameters necessary to acquire images of the chick embryo eye. Using a 9.4 Tesla (400 MHz) high field ultra-shielded and refrigerated magnet (Bruker), MRI was carried out on paraformaldehyde-fixed chick embryos or heads at E4, E6, E8, and E10. Image data were processed using established and custom packages (MRICro, ImageJ, ParaVision, Bruker and mri3dX). Voxel dimensions ranged from 62.5 microm to 117.2 microm. We subsequently used the images obtained from the MRI data in order to make precise measurements of chick embryo eye surface area, volume and axial length from E4 to E10. MRI was validated for accurate sizing of ocular tissue features by direct comparison with previously published literature. Furthermore, we demonstrate the utility of high resolution MRI for making accurate measurements of morphological changes due to experimental manipulation of chick eye development, thereby facilitating a better understanding of the effects on chick embryo eye development and growth of such manipulations. Chondroitin sulphate or heparin were microinjected into the vitreous cavity of the right eyes of each of 3 embryos at E5. At E10, embryos were fixed and various eye parameters (volume, surface area, axial length and equatorial diameter) were determined using MRI and normalised with respect to the un-injected left eyes. Statistically significant alterations in eye volume (p < 0.05; increases with chondroitin sulphate and decreases with heparin) and changes in vitreous homogeneity were observed in embryos following microinjection of glycosaminoglycans. Furthermore, in the heparin-injected eyes, significant disturbances at the vitreo-retinal boundary were observed as well as retinal folding and detachment confirming histological observations. These data reveal the utility and superiority of MRI for producing images enabling quantification of experimentally induced changes in eye volume and structure. The results indicate that MRI is an important tool that could become a routine approach for rapid and sensitive phenotypic analysis of normal chick ocular development and morphology as well as potentially the effects of surgical or genetic manipulations of chick embryo eyes in live embryos in ovo.

Apoptosis gene profiling reveals spatio-temporal regulated expression of the p53/Mdm2 pathway during lens development.

Evidence is emerging for apoptosis gene expression in the lens during development. Therefore, here we used a filter array to assess expression of 243 apoptosis-related genes in the developing postnatal mouse lens using (33)P labelled cDNA synthesized from p7 and p14 mouse lenses. We demonstrated that 161 apoptosis-related genes were expressed at levels significantly above background and 20 genes were potentially significantly differentially expressed (P<0.05) by at least 2-fold between p7 and p14. We used RT-PCR to confirm expression of these genes in newborn, p7, p14 and 4 wk mouse lens cDNA samples. Expression of 19/20 of the genes examined was confirmed, while 5 genes (Huntingtin, Mdm2, Dffa, galectin-3 and Mcl-1) were confirmed as differentially regulated between p7 and p14. RT-PCR was also used to examine the expression of the chick homologues of the most-highly expressed and/or potentially differentially regulated genes in chick embryo lenses at E6-E16. The majority of genes expressed in the postnatal mouse lens were also expressed in the chick embryo lens. Western blotting confirmed developmentally regulated expression of Axl and Mcl-1 during mouse lens development and of Mdm2, Mdm4/X and p53 during mouse and chick lens development. Western blotting also revealed the presence of p53 and Mdm4/X splice variants and/or proteolytic cleavage products in the developing lens. Since Mdm2 is a regulator of the tumour suppressor gene p53, we chose to thoroughly investigate the spatio-temporal expression patterns of p53, Mdm2 and the functionally related Mdm4/X in mouse lens development at E12.5-E16.5 using immunocytochemistry. We also examined Mdm2 expression patterns during chick lens development at E6-E16 and Mdm4/X and p53 at E14. Expression of Mdm2, Mdm4/X and p53 was spatio-temporally regulated in various compartments of the developing lens in both mouse and chick, including lens epithelial and lens fibre cells, indicating potential roles for these factors in regulation of lens epithelial cell proliferation and/or lens fibre cell differentiation This study provides a thorough initial analysis of apoptosis gene expression in the postnatal mouse lens and provides a resource for further investigation of the roles in lens development of the apoptosis genes identified. Furthermore, building on the array studies, we present the first spatio-temporal analysis of expression of p53 pathway molecules (p53, Mdm2 and Mdm4/X) in both developing mouse and chick lenses, suggesting a potential role for the p53/Mdm2 pathway in lens development, which merits further functional analysis.

Gene expression profiles during early differentiation of mouse embryonic stem cells.

BACKGROUND: Understanding the mechanisms controlling stem cell differentiation is the key to future advances in tissue and organ regeneration. Embryonic stem (ES) cell differentiation can be triggered by embryoid body (EB) formation, which involves ES cell aggregation in suspension. EB growth in the absence of leukaemia inhibitory factor (LIF) leads EBs to mimic early embryonic development, giving rise to markers representative of endoderm, mesoderm and ectoderm. Here, we have used microarrays to investigate differences in gene expression between 3 undifferentiated ES cell lines, and also between undifferentiated ES cells and Day 1-4 EBs. RESULTS: An initial array study identified 4 gene expression changes between 3 undifferentiated ES cell lines. Tissue culture conditions for ES differentiation were then optimized to give the maximum range of gene expression and growth. -Undifferentiated ES cells and EBs cultured with and without LIF at each day for 4 days were subjected to microarray analysis. -Differential expression of 23 genes was identified. 13 of these were also differentially regulated in a separate array comparison between undifferentiated ES cells and compartments of very early embryos. A high degree of inter-replicate variability was noted when confirming array results. Using a panel of marker genes, RNA amplification and RT-PCR, we examined expression pattern variation between individual -D4-Lif EBs. We found that individual EBs selected from the same dish were highly variable in gene expression profile. CONCLUSION: ES cell lines derived from different mouse strains and carrying different genetic modifications are almost invariant in gene expression profile under conditions used to maintain pluripotency. Tissue culture conditions that give the widest range of gene expression and maximise EB growth involve the use of 20% serum and starting cell numbers of 1000 per EB. 23 genes of importance to early development have been identified; more than half of these are also identified using similar studies, thus validating our results. EBs cultured in the same dish vary widely in terms of their gene expression (and hence, undoubtedly, in their future differentiation potential). This may explain some of the inherent variability in differentiation protocols that use EBs.

Developmentally regulated expression of hemoglobin subunits in avascular tissues.

We investigated the spatio-temporal profile of hemoglobin subunit expression in developing avascular tissues. Significant up-regulation of hemoglobin subunits was identified in microarray experiments comparing blastocyst inner cell masses with undifferentiated embryonic stem (ES) cells. Hemoglobin expression changes were confirmed using embryoid bodies (derived from in vitro differentiation of ES cells) to model very early development at pre-vascular stages of embryogenesis; i.e. prior to hematopoiesis. We also demonstrate, using RT-PCR, Western blotting and immunocytochemistry, expression of adult and fetal mouse hemoglobin subunits in the avascular ocular lens at various stages of development and maturation. Hemoglobin proteins were expressed in lens epithelial cells (cytoplasmic) and cortical lens fiber cells (nuclear and cell-surface-associated); however, a sensitive heme assay demonstrated negligible levels of heme in the developing lens postnatally. Hemoglobin expression was also observed in the developing eye in corneal endothelium and retinal ganglion cells. Gut sections showed, in addition to erythrocytes, hemoglobin protein staining in rare, individual villus epithelial cells. These results suggest a paradigm shift: hemoglobin subunits are expressed in the avascular lens and cornea and in pre-hematopoietic embryos. It is likely, therefore, that hemoglobin subunits have novel developmental roles; the absence of the heme group from the lens would indicate that at least some of these functions may be independent of oxygen metabolism. The pattern of expression of hemoglobin subunits in the perinuclear region during lens fiber cell differentiation, when denucleation is taking place, may indicate involvement in the apoptosis-like signaling processes occurring in differentiating lens fiber cells.

A missense mutation in the murine Opa3 gene models human Costeff syndrome.

Opa3 mRNA is expressed in all tissues examined to date, but currently the function of the OPA3 protein is unknown. Intriguingly, various mutations in the OPA3 gene lead to two similar diseases in humans: autosomal dominant inherited optic atrophy and cataract (ADOAC) and a metabolic condition; type 3-methylglutaconic aciduria (MGA). Early onset bilateral optic atrophy is a common characteristic of both disorders; retinal ganglion cells are lost and visual acuity is impaired from an early age. In order to investigate the function of the OPA3 protein, we have generated a novel ENU-induced mutant mouse carrying a missense mutation in the OPA3 gene. The heterozygous mutation in exon 2, causes an amino acid change p.L122P (c.365T>C), which is predicted to alter tertiary protein structure. In the heterozygous state, the mice appear uncompromised however; in the homozygous state mice display some of the features of MGA. Visual function is severely reduced, consistent with significant loss of retinal ganglion cells and degeneration of axons in the optic nerve. In the homozygous optic nerve, there was evidence of increased mitochondrial activity, as demonstrated by the increased presence of mitochondrial marker Cytochrome C Oxidase (COX) histochemistry. Mice homozygous for the opa3(L122P) mutation also display a severe multi-systemic disease characterized by reduced lifespan (majority dying before 4 months), decreased weight, dilated cardiomyopathy, extrapyramidal dysfunction and gross neuro-muscular defects. All of these defects are synonymous with the phenotypic characteristics of Type III MGA found in humans. This model will be of major importance for future studies of the specific function of the OPA3 gene.

Proteases in eye development and disease.

The eye is one of the classical systems in developmental biology. Furthermore, diseases of the eye, many of which have a developmental basis, have devastating effects that often result in blindness. Proteases have diverse roles in ocular physiology and pathophysiology. Here, a broad overview is provided of the recent literature pertaining to the involvement of proteases in various aspects of eye development and disease: lens development (focusing on apoptosis and lens fiber cell denucleation and organelle loss) and cataract progression, cornea development and disease, retina development and degeneration, sclera development and myopia, and the trabecular meshwork and glaucoma. Proteases discussed include caspases, calpains, matrix metalloproteases (MMPs), a disintegrin and metalloproteinases (ADAMs) and ADAM with thrombospondin motifs (ADAMTS), the ubiquitin-proteasome pathway (UPP), tissue plasminogen activator (tPA), and secretases. It is clear that proteases have diverse and important roles in ocular development and disease, and represent, in many cases, useful therapeutic targets for treating ocular conditions, which would otherwise lead to visual impairment.

Gene expression changes during cataract progression in Sparc null mice: differential regulation of mouse globins in the lens.

PURPOSE: Sparc/osteonectin is a hydroxyapatite, calcium and, collagen binding protein, implicated in tissue morphogenesis, cell proliferation, and repair. Sparc null mice develop sub-cortical posterior cataract with eventual rupture of the lens. We wished to correlate genotype with phenotype in these mice via analysis of gene expression pattern changes leading to disease. METHODS: We carried out microarray analysis of adult lenses from Sparctm1cam knockout mice on two strain backgrounds of varying phenotypic severity at two time points, 4 and 9 months. Labelled cDNA from Sparctm1cam knockout and age, strain, and sex matched control lenses was hybridized with HGMP NIA 15,000 clone set arrays. Differential expression was confirmed using semi-quantitative RT-PCR. RESULTS: We have confirmed differential expression of 54 genes. Most notably, 5 of the mouse globin genes, Hbb-b1, Hbb-b2, Hba, Hba-x, and Hbb-y and an EST, C79876, were significantly downregulated in 9-month old Sparc null mice from two genetic backgrounds at different stages of disease. Another downregulated gene, EraF, is involved in folding of globin proteins. Immune response components, including various members of the complement cascade, were upregulated in lenses with advanced cataract. CONCLUSIONS: Five mouse globins show persistent downregulation as a result of Sparc loss. We speculate as to possible roles of this phenomenon on pathogenesis of cataract in these mice. Other confirmed genes allow extension of previous models of cataract development in Sparc null mice.