Ubiquitin C-terminal hydrolase L1 (UCH-L1) is an extremely abundant protein in the brain where, remarkably, it is estimated to make up 1-5% of total neuronal protein. Although it comprises only 223 ...amino acids it has one of the most complicated 3D knotted structures yet discovered. Beyond its expression in neurons UCH-L1 has only very limited expression in other healthy tissues but it is highly expressed in several forms of cancer. Although UCH-L1 is classed as a deubiquitinating enzyme (DUB) the direct functions of UCH-L1 remain enigmatic and a wide array of alternative functions has been proposed. UCH-L1 is not essential for neuronal development but it is absolutely required for the maintenance of axonal integrity and UCH-L1 dysfunction is implicated in neurodegenerative disease. Here we review the properties of UCH-L1, and how understanding its complex structure can provide new insights into its roles in neuronal function and pathology.
Extracellular matrix (ECM) plays a central role in angiogenesis. ECM degrading enzymes breakdown the pre-existing vascular basement membrane at an early stage of angiogenesis and subsequently degrade ...stromal ECM as the new vessels invade into tissues. Conversely certain ECM components including collagen, fibronectin or fibrin are required for endothelial cell migration and tube morphogenesis. As the new vessels form they lay down a basement membrane that surrounds the endothelial tubes and is essential for their stability. In the rodent eye the transient expression of fibronectin and matricellular proteins plays a key role in retinal vascular development. In pathological retinal angiogenesis, such as in proliferative diabetic retinopathy, preretinal neovascularization occurs where new blood vessels invade the cortical vitreous gel and these blood vessels require vitreous collagen for their growth. The vitreous is normally anti-angiogenic and contains endogenous ECM inhibitors of angiogenesis including opticin and thombospondins, and ECM fragments such as endostatin. In preretinal neovascularization, the combined anti-angiogenic effects of these molecules are overcome by an excess of growth factors such as vascular endothelial growth factor-A, and new vessels grow into the vitreous with potentially blinding sequelae.
•Extracellular matrix (ECM) breakdown and formation are essential processes in angiogenesis.•Signalling from specific ECM components via integrins is required for angiogenesis.•ECM components involved in retinal vascular devlopment: fibronectin, thrombospondin-1, laminin, type XVIII collagen, CCN1.•Vitreous collagen provides an essential substrate in preretinal neovascularization.•ECM components that act as angiogenic inhibitors in vitreous include opticin, thrombospondins and endostatin.
Complement turnover is tightly regulated throughout the human body in order to prevent over-activation and subsequent damage from inflammation. In the eye, low-level complement activation is ...maintained to provide immune tolerance in this immune privileged organ. Conversely, the complement system is suppressed in the cornea to protect it from continuous immunological insult. Over-activation of the complement cascade has been implicated in the disease progression of glaucoma and diabetic retinopathy and is now known to be a central driver in the pathogenesis of age-related macular degeneration (AMD). Indeed, it is with AMD where the most recent and exciting work has been carried out with complement-based therapies entering into clinical trials. However, the success of these trials will depend upon delivering the therapeutics to the correct anatomical sites within the eye, so a full understanding of how complement regulation is compartmentalized in the eye is required, a topic that will be highlighted in this review.
The monocarboxylate transporter 1 (MCT1) inhibitor, AZD3965, is undergoing phase I evaluation in the United Kingdom. AZD3965 is proposed, via lactate transport modulation, to kill tumor cells reliant ...on glycolysis. We investigated the therapeutic potential of AZD3965 in small cell lung cancer (SCLC) seeking rationale for clinical testing in this disease and putative predictive biomarkers for trial use.
AZD3965 sensitivity was determined for seven SCLC cell lines, in normoxia and hypoxia, and for a tumor xenograft model. Proof of mechanism was sought via changes in intracellular/tumor lactate. Expression of MCT1 and related transporter MCT4 was assessed by Western blot analysis. Drug resistance was investigated via MCT4 siRNAi and overexpression. The expression and clinical significance of MCT1 and MCT4 were explored in a tissue microarray (TMA) from 78 patients with SCLC.
AZD3965 sensitivity varied in vitro and was highest in hypoxia. Resistance in hypoxia was associated with increased MCT4 expression. In vivo, AZD3965 reduced tumor growth and increased intratumor lactate. In the TMA, high MCT1 expression was associated with worse prognosis (P = 0.014). MCT1 and hypoxia marker CA IX expression in the absence of MCT4 was observed in 21% of SCLC tumors.
This study provides a rationale to test AZD3965 in patients with SCLC. Our results suggest that patients with tumors expressing MCT1 and lacking in MCT4 are most likely to respond.
Many retinal dystrophies result in photoreceptor loss, but the inner retinal neurons can survive, making them potentially amenable to emerging optogenetic therapies. Here, we show that ectopically ...expressed human rod opsin, driven by either a non-selective or ON-bipolar cell-specific promoter, can function outside native photoreceptors and restore visual function in a mouse model of advanced retinal degeneration. Electrophysiological recordings from retinal explants and the visual thalamus revealed changes in firing (increases and decreases) induced by simple light pulses, luminance increases, and naturalistic movies in treated mice. These responses could be elicited at light intensities within the physiological range and substantially below those required by other optogenetic strategies. Mice with rod opsin expression driven by the ON-bipolar specific promoter displayed behavioral responses to increases in luminance, flicker, coarse spatial patterns, and elements of a natural movie at levels of contrast and illuminance (≈50–100 lux) typical of natural indoor environments. These data reveal that virally mediated ectopic expression of human rod opsin can restore vision under natural viewing conditions and at moderate light intensities. Given the inherent advantages in employing a human protein, the simplicity of this intervention, and the quality of vision restored, we suggest that rod opsin merits consideration as an optogenetic actuator for treating patients with advanced retinal degeneration.
•Ectopic human rod opsin restores visual functions in advanced retinal degeneration•Rod opsin has greater sensitivity than current optogenetic strategies•Rod opsin-treated animals respond to spatial stimuli, flicker, and natural scenes•As a human protein ordinarily found in retinal tissue, barriers to clinic are minimized
Cehajic-Kapetanovic at al. show that ectopically expressed human rod opsin restores vision in a mouse model of advanced retinal degeneration. The quality of the restored vision compares favorably, especially in terms of sensitivity, with alternative approaches, and using a native human protein reduces barriers to future clinical trials.
Abstract The essential trace metals iron, zinc, and copper play important roles both in retinal physiology and disease. They are involved in various retinal functions such as phototransduction, the ...visual cycle, and the process of neurotransmission, being tightly bound to proteins and other molecules to regulate their structure and/or function or as unbound free metal ions. Elevated levels of “free” or loosely bound metal ions can exert toxic effects, and in order to maintain homeostatic levels to protect retinal cells from their toxicity, appropriate mechanisms exist such as metal transporters, chaperones, and the presence of certain storage molecules that tightly bind metals to form nontoxic products. The pathways to maintain homeostatic levels of metals are closely interlinked, with various metabolic pathways directly and/or indirectly affecting their concentrations, compartmentalization, and oxidation/reduction states. Retinal deficiency or excess of these metals can result from systemic depletion and/or overload or from mutations in genes involved in maintaining retinal metal homeostasis, and this is associated with retinal dysfunction and pathology. Iron accumulation in the retina, a characteristic of aging, may be involved in the pathogenesis of retinal diseases such as age-related macular degeneration (AMD). Zinc deficiency is associated with poor dark adaptation. Zinc levels in the human retina and RPE decrease with age in AMD. Copper deficiency is associated with optic neuropathy, but retinal function is maintained. The changes in iron and zinc homeostasis in AMD have led to the speculation that iron chelation and/or zinc supplements may help in its treatment.
Age-related macular degeneration (AMD) is a leading cause of blindness. Genetic variants at the chromosome 1q31.3 encompassing the complement factor H (CFH, FH) and CFH related genes (CFHR1-5) are ...major determinants of AMD susceptibility, but their molecular consequences remain unclear. Here we demonstrate that FHR-4 plays a prominent role in AMD pathogenesis. We show that systemic FHR-4 levels are elevated in AMD (P-value = 7.1 × 10
), whereas no difference is seen for FH. Furthermore, FHR-4 accumulates in the choriocapillaris, Bruch's membrane and drusen, and can compete with FH/FHL-1 for C3b binding, preventing FI-mediated C3b cleavage. Critically, the protective allele of the strongest AMD-associated CFH locus variant rs10922109 has the highest association with reduced FHR-4 levels (P-value = 2.2 × 10
), independently of the AMD-protective CFHR1-3 deletion, and even in those individuals that carry the high-risk allele of rs1061170 (Y402H). Our findings identify FHR-4 as a key molecular player contributing to complement dysregulation in AMD.
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