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Advances in Experimental Medicine and... 2019Retinal degeneration includes a variety of diseases for which there is no regenerative therapy. Cellular transplantation is one potential approach for future therapy for... (Review)
Review
Retinal degeneration includes a variety of diseases for which there is no regenerative therapy. Cellular transplantation is one potential approach for future therapy for retinal degeneration, and stem cells have emerged as a promising source for future cell therapeutics. One major barrier to therapy is the ability to specify individual photoreceptor lineages from a variety of stem cell sources. In this review, we focus on photoreceptor genesis from progenitor populations in the developing embryo and how this understanding has given us the tools to manipulate cultures to specific unique rod and cone lineages from adult stem cell populations. We discuss experiments and evidence uncovering the lineage mechanisms at play in the establishment of fate-specific rod and cone photoreceptor progenitors. This may lead to an improved understanding of retinal development in vivo, as well as new cell sources for transplantation.
Topics: Cell Differentiation; Humans; Retina; Retinal Cone Photoreceptor Cells; Retinal Degeneration; Retinal Rod Photoreceptor Cells; Stem Cells
PubMed: 31884669
DOI: 10.1007/978-3-030-27378-1_90 -
Bulletin of Experimental Biology and... May 2021We developed a model of retinal degeneration in rabbits based on exposure to light with a wavelength of 405 nm. This model allows reproducing structural and functional...
We developed a model of retinal degeneration in rabbits based on exposure to light with a wavelength of 405 nm. This model allows reproducing structural and functional disorders in the central parts of the retina, including primarily degeneration of the outer layers of the retina (retinal pigment epithelium and layer of photoreceptor cells), and is designed to study the mechanisms of formation, progression and effectiveness of new drugs and methods of treatment of degenerative diseases of the retina.
Topics: Adaptation, Ocular; Animals; Disease Models, Animal; Light; Male; Photoreceptor Cells; Rabbits; Retina; Retinal Degeneration
PubMed: 34173098
DOI: 10.1007/s10517-021-05213-4 -
Eye (London, England) Feb 2016It might seem a little ridiculous to cover the period over which vision evolved, perhaps 1.5 billion years, in only 3000 words. Yet, if we examine the photoreceptor... (Review)
Review
It might seem a little ridiculous to cover the period over which vision evolved, perhaps 1.5 billion years, in only 3000 words. Yet, if we examine the photoreceptor molecules of the most basic eukaryote protists and even before that, in those of prokaryote bacteria and cyanobacteria, we see how similar they are to those of mammalian rod and cone photoreceptor opsins and the photoreceptive molecules of light sensitive ganglion cells. This shows us much with regard the development of vision once these proteins existed, but there is much more to discover about the evolution of even more primitive vision systems.
Topics: Animals; Evolution, Molecular; Humans; Light Signal Transduction; Opsins; Photoreceptor Cells, Invertebrate; Photoreceptor Cells, Vertebrate; Photoreceptors, Plant; Vision, Ocular
PubMed: 26541087
DOI: 10.1038/eye.2015.220 -
Pflugers Archiv : European Journal of... Sep 2021The rod and cone photoreceptor cells of the vertebrate retina have highly specialized structures that enable them to carry out their function of light detection over a... (Review)
Review
The rod and cone photoreceptor cells of the vertebrate retina have highly specialized structures that enable them to carry out their function of light detection over a broad range of illumination intensities with optimized spatial and temporal resolution. Most prominent are their unusually large sensory cilia, consisting of outer segments packed with photosensitive disc membranes, a connecting cilium with many features reminiscent of the primary cilium transition zone, and a pair of centrioles forming a basal body which serves as the platform upon which the ciliary axoneme is assembled. These structures form a highway through which an enormous flux of material moves on a daily basis to sustain the continual turnover of outer segment discs and the energetic demands of phototransduction. After decades of study, the details of the fine structure and distribution of molecular components of these structures are still incompletely understood, but recent advances in cellular imaging techniques and animal models of inherited ciliary defects are yielding important new insights. This knowledge informs our understanding both of the mechanisms of trafficking and assembly and of the pathophysiological mechanisms of human blinding ciliopathies.
Topics: Animals; Cilia; Humans; Retinal Cone Photoreceptor Cells; Retinal Photoreceptor Cell Inner Segment; Retinal Photoreceptor Cell Outer Segment
PubMed: 34050409
DOI: 10.1007/s00424-021-02564-9 -
Pflugers Archiv : European Journal of... Sep 2021In the vertebrate retina, signals generated by cones of different spectral preference and by highly sensitive rod photoreceptors interact at various levels to extract... (Review)
Review
In the vertebrate retina, signals generated by cones of different spectral preference and by highly sensitive rod photoreceptors interact at various levels to extract salient visual information. The first opportunity for such interaction is offered by electrical coupling of the photoreceptors themselves, which is mediated by gap junctions located at the contact points of specialised cellular processes: synaptic terminals, telodendria and radial fins. Here, we examine the evolutionary pressures for and against interphotoreceptor coupling, which are likely to have shaped how coupling is deployed in different species. The impact of coupling on signal to noise ratio, spatial acuity, contrast sensitivity, absolute and increment threshold, retinal signal flow and colour discrimination is discussed while emphasising available data from a variety of vertebrate models spanning from lampreys to primates. We highlight the many gaps in our knowledge, persisting discrepancies in the literature, as well as some major unanswered questions on the actual extent and physiological role of cone-cone, rod-cone and rod-rod communication. Lastly, we point toward limited but intriguing evidence suggestive of the ancestral form of coupling among ciliary photoreceptors.
Topics: Animals; Gap Junctions; Humans; Retinal Cone Photoreceptor Cells; Retinal Rod Photoreceptor Cells; Synapses
PubMed: 33988778
DOI: 10.1007/s00424-021-02572-9 -
The Journal of Membrane Biology Oct 2019Rhodopsin is the light receptor in photoreceptor cells of the retina and a prototypical G protein-coupled receptor. Two types of quaternary structures can be adopted by... (Review)
Review
Rhodopsin is the light receptor in photoreceptor cells of the retina and a prototypical G protein-coupled receptor. Two types of quaternary structures can be adopted by rhodopsin. If rhodopsin folds and attains a proper tertiary structure, it can then form oligomers and nanodomains within the photoreceptor cell membrane. In contrast, if rhodopsin misfolds, it cannot progress through the biosynthetic pathway and instead will form aggregates that can cause retinal degenerative disease. In this review, emerging views are highlighted on the supramolecular organization of rhodopsin within the membrane of photoreceptor cells and the aggregation of rhodopsin that can lead to retinal degeneration.
Topics: Animals; Cell Membrane; Humans; Photoreceptor Cells, Vertebrate; Protein Domains; Protein Folding; Retinal Degeneration; Rhodopsin
PubMed: 31286171
DOI: 10.1007/s00232-019-00078-1 -
Advances in Experimental Medicine and... 2018Unlike rod monochromatism, which is an autosomal recessive disease that affects all three types of cones, blue cone monochromatism (BCM) is an X-linked disease that... (Review)
Review
Unlike rod monochromatism, which is an autosomal recessive disease that affects all three types of cones, blue cone monochromatism (BCM) is an X-linked disease that affects only L-cones and M-cones. The rods and S-cones are normal. The estimated prevalence is 1 in 100,00 individuals.
Topics: Color Vision Defects; Genetic Diseases, X-Linked; Humans; Retinal Cone Photoreceptor Cells; Retinal Rod Photoreceptor Cells
PubMed: 30578487
DOI: 10.1007/978-3-319-95046-4_14 -
Progress in Brain Research 2022For more than two centuries scientists and engineers have worked to understand and model how the eye encodes electromagnetic radiation (light). We now understand the...
For more than two centuries scientists and engineers have worked to understand and model how the eye encodes electromagnetic radiation (light). We now understand the principles of how light is transmitted through the optics of the eye and encoded by retinal photoreceptors and light-sensitive neurons. In recent years, new instrumentation has enabled scientists to measure the specific parameters of the optics and photoreceptor encoding. We implemented the principles and parameter estimates that characterize the human eye in an open-source software toolbox. This chapter describes the principles behind these tools and illustrates how to use them to compute the initial visual encoding.
Topics: Humans; Optics and Photonics; Photoreceptor Cells, Vertebrate; Retina; Retinal Cone Photoreceptor Cells; Software
PubMed: 35940717
DOI: 10.1016/bs.pbr.2022.04.006 -
Trends in Endocrinology and Metabolism:... Jan 2019Ubiquitous in non-mammalian vertebrates, extra-retinal photoreceptors (ERPs) have been linked to an array of physiological, metabolic, behavioral, and morphological... (Comparative Study)
Comparative Study Review
Ubiquitous in non-mammalian vertebrates, extra-retinal photoreceptors (ERPs) have been linked to an array of physiological, metabolic, behavioral, and morphological changes. However, the mechanisms and functional roles of ERPs remain one of the enduring questions of modern biology. In this review article, we use a comparative framework to identify conserved roles and distributions of ERPs, highlighting knowledge gaps. We conclude that ERP research can be divided into two largely unconnected categories: (i) identification and localization of photoreceptors and (ii) linkage of non-retinal light reception to behavioral and physiological processes, particularly endocrine systems. However, the emergence of novel gene editing and silencing techniques is enabling the unification of ERP research by allowing the bridging of this divide.
Topics: Animals; Behavior, Animal; Brain; Opsins; Photoperiod; Photoreceptor Cells; Vertebrates
PubMed: 30522810
DOI: 10.1016/j.tem.2018.10.005 -
International Journal of Molecular... May 2021Retinoprotective proteins play important roles for retinal tissue integrity. They can directly affect the function and the survival of photoreceptors, and/or indirectly... (Review)
Review
Retinoprotective proteins play important roles for retinal tissue integrity. They can directly affect the function and the survival of photoreceptors, and/or indirectly target the retinal pigment epithelium (RPE) and endothelial cells that support these tissues. Retinoprotective proteins are used in basic, translational and in clinical studies to prevent and treat human retinal degenerative disorders. In this review, we provide an overview of proteins that protect the retina and focus on pigment epithelium-derived factor (PEDF), and its effects on photoreceptors, RPE cells, and endothelial cells. We also discuss delivery systems such as pharmacologic and genetic administration of proteins to achieve photoreceptor survival and retinal tissue integrity.
Topics: Animals; Endothelial Cells; Eye Proteins; Humans; Nerve Growth Factors; Photoreceptor Cells; Photoreceptor Cells, Vertebrate; Protein Transport; Retina; Retinal Degeneration; Retinal Neurons; Retinal Pigment Epithelium; Serpins
PubMed: 34069505
DOI: 10.3390/ijms22105344