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Retinal signal processing

Xujiao Zhou, Rong Zhang, Shenghai Zhang, Jihong Wu, Xinghuai Sun
Serotonin receptor agonists are neuroprotective in central nervous system (CNS) injury models. However, the neuroprotective functional implications and synaptic mechanism of 8-OH-DPAT, a serotonin receptor (5-HT1A) agonist, in an adult male Wistar rat model of chronic glaucoma model remain unknown. We found that ocular hypertension decreased 5-HT1A receptor expression in rat retinas, as the number of retinal ganglion cells (RGCs) was significantly reduced in rats with induced ocular hypertension relative to that in control retinas, and 8-OH-DPAT enhanced the RGC viability...
December 12, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Rowena Almonte-Baldonado, Arturo Bravo-Nuevo, Damien Gerald, Laura E Benjamin, George C Prendergast, Lisa D Laury-Kleintop
Neovascularization in cancer or retinopathy is driven by pathological changes that foster abnormal sprouting of endothelial cells. Mouse genetic studies indicate that the stress-induced small GTPase RhoB is dispensable for normal physiology but required for pathogenic angiogenesis. In diabetic retinopathy, retinopathy of prematurity (ROP) or age-related wet macular degeneration (AMD), progressive pathologic anatomic changes and ischemia foster neovascularization are characterized by abnormal sprouting of endothelial cells...
December 9, 2018: Journal of Cellular Biochemistry
Marita Pietrucha-Dutczak, Marialaura Amadio, Stefano Govoni, Joanna Lewin-Kowalik, Adrian Smedowski
Retinal neurons are not able to undergo spontaneous regeneration in response to damage. A variety of stressors, i.e., UV radiation, high temperature, ischemia, allergens, and others, induce reactive oxygen species production, resulting in consecutive alteration of stress-response gene expression and finally can lead to cell apoptosis. Neurons have developed their own endogenous cellular protective systems. Some of them are preventing cell death and others are allowing functional recovery after injury. The high efficiency of these mechanisms is crucial for cell survival...
2018: Frontiers in Neuroscience
Yi Huang, Yan Chen, Amanda Marie Shaw, Howard Goldfine, Junqiang Tian, Jiyang Cai
Signaling pathways mediated by the mechanistic target of rapamycin (mTOR) play key roles in aging and age-related diseases. As a downstream protein of mTOR, transcription factor EB (TFEB) controls lysosome biogenesis and cellular trafficking, processes that are essential for the functions of phagocytic cells like the retinal pigment epithelium (RPE). In the current study, we show that a naturally occurring polyphenolic compound, quercetin, promoted TFEB nuclear translocation and enhanced its transcriptional activity in cultured RPE cells...
2018: Oxidative Medicine and Cellular Longevity
Billie Beckwith-Cohen, Lars C Holzhausen, Tzu-Ming Wang, Rajit Rajappa, Richard H Kramer
Lateral inhibition in the vertebrate retina depends on a negative feedback synapse between horizontal cells (HCs) and rod and cone photoreceptors. A change in pH is thought to be the signal for negative feedback, but its spatial profile in the synaptic cleft is unknown. Here we use 3 different membrane proteins, each fused to the same genetically-encoded pH-sensitive GFP (pHluorin), to probe synaptic pH in retina from transgenic zebrafish ( Danio rerio ) of either sex. We used the cone transducin promoter to express SynaptopHluorin (pHluorin on VAMP2) or CalipHluorin (pHluorin on an L-type Ca2+ channel) and the HC-specific connexin-55...
November 30, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Yi Liu, Guo-Bin Zhuang, Xue-Zhi Zhou
High-mobility group box 1 (HMGB1) is a nuclear protein that can also act as an extracellular trigger of inflammation, proliferation, and migration in eye diseases. It induces signaling pathways by binding to the receptor for advanced glycation end products (RAGE) and Toll-like receptors (TLRs) 2, 4, and 9. This proinflammatory activity is considered to be important in the pathogenesis of a wide range of ocular diseases resulting from hemodynamic changes, presence of neovascular endothelial cells, secretion of intraocular immune factors or inflammation, and apoptosis of retinal cell layers...
2018: Journal of Ophthalmology
Alexander Meadway, Lawrence C Sincich
The light capturing properties of cone photoreceptors create the elementary signals that form the basis of vision. Variation in the amplitude of individual cone signals has been found physiologically as part of normal retinal circuit processing. Less well characterized is how cone signals may vary due to purely optical properties. We present a model of light propagation in cones using a finite difference beam propagation method to simulate how light from a small stimulus travels through a cone plus its immediate neighbors...
November 1, 2018: Biomedical Optics Express
Margaret L Veruki, Yifan Zhou, Áurea Castilho, Catherine W Morgans, Espen Hartveit
In the rod pathway of the mammalian retina, axon terminals of glutamatergic rod bipolar cells are presynaptic to AII and A17 amacrine cells in the inner plexiform layer. Recent evidence suggests that both amacrines express NMDA receptors, raising questions concerning molecular composition, localization, activation, and function of these receptors. Using dual patch-clamp recording from synaptically connected rod bipolar and AII or A17 amacrine cells in retinal slices from female rats, we found no evidence that NMDA receptors contribute to postsynaptic currents evoked in either amacrine...
November 20, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Tylor R Lewis, Sean R Kundinger, Brian A Link, Christine Insinna, Joseph C Besharse
BACKGROUND: KIF17, a kinesin-2 motor that functions in intraflagellar transport, can regulate the onset of photoreceptor outer segment development. However, the function of KIF17 in a mature photoreceptor remains unclear. Additionally, the ciliary localization of KIF17 is regulated by a C-terminal consensus sequence (KRKK) that is immediately adjacent to a conserved residue (mouse S1029/zebrafish S815) previously shown to be phosphorylated by CaMKII. Yet, whether this phosphorylation can regulate the localization, and thus function, of KIF17 in ciliary photoreceptors remains unknown...
November 20, 2018: BMC Cell Biology
Samih Alqawlaq, John G Flanagan, Jeremy M Sivak
Glaucoma describes a distinct optic neuropathy with complex etiology and a variety of associated risk factors, but with similar pathological endpoints. Risk factors such as age, increased intraocular pressure (IOP), low mean arterial pressure, and autoimmune disease, can all be associated with death of retinal ganglion cells (RGCs) and optic nerve head remodeling. Today, IOP management remains the standard of care, even though IOP elevation is not pathognomonic of glaucoma, and patients can continue to lose vision despite effective IOP control...
November 14, 2018: Experimental Eye Research
Sarita Rani Patnaik, Viola Kretschmer, Lena Brücker, Sandra Schneider, Ann-Kathrin Volz, Liliana Del Rocio Oancea-Castillo, Helen Louise May-Simera
Primary cilia are conserved organelles that mediate cellular communication crucial for organogenesis and homeostasis in numerous tissues. The retinal pigment epithelium (RPE) is a ciliated monolayer in the eye that borders the retina and is vital for visual function. Maturation of the RPE is absolutely critical for visual function and the role of the primary cilium in this process has been largely ignored to date. We show that primary cilia are transiently present during RPE development and that as the RPE matures, primary cilia retract, and gene expression of ciliary disassembly components decline...
November 16, 2018: Cellular and Molecular Life Sciences: CMLS
Liwei Wang, Yuejie Li, Yilu Li, Kaining Li
Optical coherence tomography (OCT) is becoming a clinically useful and important imaging technique due to its ability to provide high-resolution structural imaging in vivo . Optical coherence tomography angiography (OCTA) can visualize vasculature imaging of biological tissues. With the advent of Fourier-domain OCT, numerous OCTA techniques have been developed to detect the microvasculature in vivo. The macular region of the fundus is separated into retinal and choroid regions by segmentation algorithm in the data processing, a false blood flow signal is generated due to bulk motion when vasculature imaging was segmented in the retinal regions...
2018: American Journal of Translational Research
Man Wang, Yangningzhi Wang, Tianhua Xie, Pengfei Zhan, Jian Zou, Xiaowei Nie, Jun Shao, Miao Zhuang, Chengye Tan, Jianxin Tan, Youai Dai, Jie Sun, Jiantao Li, Yuehua Li, Qian Shi, Jing Leng, Xiaolu Wang, Yong Yao
AIMS/HYPOTHESIS: Diabetic retinopathy is a common microvascular complication of diabetes mellitus and is initiated by inflammation and apoptosis-associated retinal endothelial cell damage. Prostaglandin E2 (PGE2 ) has emerged as a critical regulator of these biological processes. We hypothesised that modulating PGE2 and its E-prostanoid receptor (EP2 R) would prevent diabetes mellitus-induced inflammation and microvascular dysfunction. METHODS: In a streptozotocin (STZ)-induced rat model of diabetes, rats received intravitreal injection of PGE2 , butaprost (a PGE2 /EP2 R agonist) or AH6809 (an EP2 R antagonist)...
November 8, 2018: Diabetologia
Subhadip Senapati, Paul S-H Park
Membrane proteins play an integral role in cellular communication. They are often organized within the crowded cell membrane into nanoscale domains (i.e., nanodomains), which facilitates their function in cell signaling processes. The visualization of membrane proteins and nanodomains within biological membranes under physiological conditions presents a challenge and is not possible using conventional microscopy methods. Atomic force microscopy (AFM) provides an opportunity to study the organization of membrane proteins within biological membranes with sub-nanometer resolution...
2019: Methods in Molecular Biology
Jiachen Yang, Kyohoon Sim, Xinbo Gao, Wen Lu, Qinggang Meng, Baihua Li
Most of the current blind stereoscopic image quality assessment (SIQA) algorithms cannot show reliable accuracy. One reason is that they do not have the deep architectures and the other reason is that they are designed on the relatively weak biological basis, compared with findings on human visual system (HVS). In this paper, we propose a Deep Edge and COlor Signal INtegrity Evaluator (DECOSINE) based on the whole visual perception route from eyes to the frontal lobe, and especially focus on edge and color signal processing in retinal ganglion cells (RGC) and lateral geniculate nucleus (LGN)...
October 26, 2018: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
Hiroshi Tanahashi, Tatsuo Suzuki
Microphthalmia is a malformation that reduces the size of the ocular globe. The etiologies of this anomaly are various, but the genetic background appears to have a predominant influence on its development through mutations of genes controlling ocular developmental processes. LRP4 is a type I single transmembrane protein that is essential for the formation of neuromuscular junctions. We created and experimented on homozygous Lrp4-deficient mice and found the microphthalmia phenotype in their eyes. The loss of Lrp4 resulted in an elevated incidence of microphthalmia and affected the mRNA expression of the members of bone morphogenetic protein, fibroblast growth factor, Sonic hedgehog, and WNT signaling pathways and of several pathogenic genes for microphthalmia...
October 20, 2018: Biochemical and Biophysical Research Communications
Umar Sharif, Nur Musfirah Mahmud, Paul Kay, Yit C Yang, Simon P Harding, Ian Grierson, Tengku Ain Kamalden, Malcolm J Jackson, Luminita Paraoan
The retinal pigment epithelium (RPE) plays a central role in neuroretinal homoeostasis throughout life. Altered proteolysis and inflammatory processes involving RPE contribute to the pathophysiology of age-related macular degeneration (AMD), but the link between these remains elusive. We report for the first time the effect of advanced glycation end products (AGE)-known to accumulate on the ageing RPE's underlying Bruch's membrane in situ-on both key lysosomal cathepsins and NF-κB signalling in RPE. Cathepsin L activity and NF-κB effector levels decreased significantly following 2-week AGE exposure...
October 19, 2018: Journal of Cellular and Molecular Medicine
F Li, Y Liu, L Ren, Q Sun, Y-X Luo
OBJECTIVE: To investigate the effect of insulin-like growth factor (IGF)-1 on regulating the occurrence of retinal neovascularization and the expression mechanism of Angiotensin II (Ang II) and vascular endothelial factor (VEGF). MATERIALS AND METHODS: A total of 40 C57BL/6J healthy mice of either gender were selected, and randomly divided into 4 groups: control group, model group, IGF-1 overexpression carrier intervention group and IGF-1 siRNA intervention group (10 in each group)...
October 2018: European Review for Medical and Pharmacological Sciences
Xinhua Zheng, Qian Liu, Ming Yi, Shuang Qin, Kongming Wu
Tumor environment plays a pivotal role in determining cancer biology characteristics. Cytokine factors, as a critical component in tumor milieu, execute distinct functions in the process of tumorigenesis and progression via the autocrine or paracrine manner. The retinal determination gene network (RDGN), which mainly comprised DACH, SIX, and EYA family members, is required for the organ development in mammalian species. While the aberrant expression of RDGN is involved in the proliferation, apoptosis, angiogenesis, and metastasis of tumors via interacting with different cytokine-related signals, such as CXCL8, IL-6, TGF-β, FGF, and VEGF, in a cell- or tissue-dependent manner...
2018: OncoTargets and Therapy
Michael Barnett-Cowan, Marc O Ernst, Heinrich H Bülthoff
In environments where orientation is ambiguous, the visual system uses prior knowledge about lighting coming from above to recognize objects, determine which way is up, and reorient the body. Here we investigated the extent with which assumed light from above preferences are affected by body orientation and the orientation of the retina relative to gravity. We tested the ability to extract shape-from-shading with seven human male observers positioned in multiple orientations relative to gravity using a modified KUKA anthropomorphic robot arm...
October 11, 2018: Scientific Reports
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