Functional compartmentalization of photoreceptor neurons

In vivotissue-specific chromatin profiling inDrosophila melanogasterusing GFP-tagged nuclei

10.1101/2021.03.23.436625 ◽

2021 ◽

Author(s):

Juan Jauregui-Lozano ◽

Kimaya Bakhle ◽

Vikki M. Weake

Keyword(s):

Cell Types ◽

Chromatin Accessibility ◽

Chromatin State ◽

Specific Cell ◽

Histone Marks ◽

The Many ◽

Chromatin Profiling ◽

Photoreceptor Neurons ◽

Multicellular Organisms

AbstractThe chromatin landscape defines cellular identity in multicellular organisms with unique patterns of DNA accessibility and histone marks decorating the genome of each cell type. Thus, profiling the chromatin state of different cell types in an intact organism under disease or physiological conditions can provide insight into how chromatin regulates cell homeostasisin vivo. To overcome the many challenges associated with characterizing chromatin state in specific cell types, we developed an improved approach to isolateDrosophilanuclei tagged with GFP expressed under Gal4/UAS control. Using this protocol, we profiled chromatin accessibility using Omni-ATAC, and examined the distribution of histone marks using ChIP-seq and CUT&Tag in adult photoreceptor neurons. We show that the chromatin landscape of photoreceptors reflects the transcriptional state of these cells, demonstrating the quality and reproducibility of our approach for profiling the transcriptome and epigenome of specific cell types inDrosophila.

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Loss of PRCD alters number and packaging density of rhodopsin in rod photoreceptor disc membranes

Scientific Reports ◽

10.1038/s41598-020-74628-2 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Emily R. Sechrest ◽

Joseph Murphy ◽

Subhadip Senapati ◽

Andrew F. X. Goldberg ◽

Paul S.-H. Park ◽

...

Keyword(s):

High Fidelity ◽

Rod Photoreceptor ◽

Photoreceptor Degeneration ◽

Wild Type ◽

Photoreceptor Outer Segment ◽

Rod Photoreceptors ◽

Force Microscopy ◽

Atomic Force ◽

Photoreceptor Neurons ◽

Precise Role

Abstract Progressive rod-cone degeneration (PRCD) is a small protein localized to photoreceptor outer segment (OS) disc membranes. Several mutations in PRCD are linked to retinitis pigmentosa (RP) in canines and humans, and while recent studies have established that PRCD is required for high fidelity disc morphogenesis, its precise role in this process remains a mystery. To better understand the part which PRCD plays in disease progression as well as its contribution to photoreceptor OS disc morphogenesis, we generated a Prcd-KO animal model using CRISPR/Cas9. Loss of PRCD from the retina results in reduced visual function accompanied by slow rod photoreceptor degeneration. We observed a significant decrease in rhodopsin levels in Prcd-KO retina prior to photoreceptor degeneration. Furthermore, ultrastructural analysis demonstrates that rod photoreceptors lacking PRCD display disoriented and dysmorphic OS disc membranes. Strikingly, atomic force microscopy reveals that many disc membranes in Prcd-KO rod photoreceptor neurons are irregular, containing fewer rhodopsin molecules and decreased rhodopsin packing density compared to wild-type discs. This study strongly suggests an important role for PRCD in regulation of rhodopsin incorporation and packaging density into disc membranes, a process which, when dysregulated, likely gives rise to the visual defects observed in patients with PRCD-associated RP.

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Protein Sorting in Healthy and Diseased Photoreceptors

Annual Review of Vision Science ◽

10.1146/annurev-vision-091718-014843 ◽

2019 ◽

Vol 5 (1) ◽

pp. 73-98 ◽

Cited By ~ 1

Author(s):

Yoshikazu Imanishi

Keyword(s):

Signal Transduction ◽

Membrane Protein ◽

Outer Segment ◽

Protein Sorting ◽

Rods And Cones ◽

Retinal Photoreceptor ◽

Photoreceptor Neurons ◽

Cellular Compartments ◽

G Protein Coupled ◽

Distinct Membrane

Rods and cones are retinal photoreceptor neurons required for our visual sensation. Because of their highly polarized structures and well-characterized processes of G protein–coupled receptor–mediated phototransduction signaling, these photoreceptors have been excellent models for studying the compartmentalization and sorting of proteins. Rods and cones have a modified ciliary compartment called the outer segment (OS) as well as non-OS compartments. The distinct membrane protein compositions between OS and non-OS compartments suggest that the OS is separated from the rest of the cellular compartments by multiple barriers or gates that are selectively permissive to specific cargoes. This review discusses the mechanisms of protein sorting and compartmentalization in photoreceptor neurons. Proper sorting and compartmentalization of membrane proteins are required for signal transduction and transmission. This review also discusses the roles of compartmentalized signaling, which is compromised in various retinal ciliopathies.

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The synaptic vesicle SNARE neuronal Synaptobrevin promotes endolysosomal degradation and prevents neurodegeneration

The Journal of Cell Biology ◽

10.1083/jcb.201108088 ◽

2012 ◽

Vol 196 (2) ◽

pp. 261-276 ◽

Cited By ~ 25

Author(s):

Adam Haberman ◽

W. Ryan Williamson ◽

Daniel Epstein ◽

Dong Wang ◽

Srisha Rina ◽

...

Keyword(s):

Synaptic Vesicle ◽

Transmembrane Protein ◽

Primary Defect ◽

Endosomal Sorting ◽

Synaptic Vesicle Exocytosis ◽

Cathepsin Proteases ◽

Core Proteins ◽

Protein Receptors ◽

Vesicle Exocytosis ◽

Photoreceptor Neurons

Soluble NSF attachment protein receptors (SNAREs) are the core proteins in membrane fusion. The neuron-specific synaptic v-SNARE n-syb (neuronal Synaptobrevin) plays a key role during synaptic vesicle exocytosis. In this paper, we report that loss of n-syb caused slow neurodegeneration independent of its role in neurotransmitter release in adult Drosophila melanogaster photoreceptor neurons. In addition to synaptic vesicles, n-Syb localized to endosomal vesicles. Loss of n-syb lead to endosomal accumulations, transmembrane protein degradation defects, and a secondary increase in autophagy. Our evidence suggests a primary defect of impaired delivery of vesicles that contain degradation proteins, including the acidification-activated Cathepsin proteases and the neuron-specific proton pump and V0 adenosine triphosphatase component V100. Overexpressing V100 partially rescued n-syb–dependent degeneration through an acidification-independent endosomal sorting mechanism. Collectively, these findings reveal a role for n-Syb in a neuron-specific sort-and-degrade mechanism that protects neurons from degeneration. Our findings further shed light on which intraneuronal compartments exhibit increased or decreased neurotoxicity.

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A non‐canonical rhodopsin‐mediated insulin receptor signaling pathway in retinal photoreceptor neurons

Cell Biology International ◽

10.1002/cbin.11299 ◽

2020 ◽

Vol 44 (4) ◽

pp. 1020-1027 ◽

Cited By ~ 2

Author(s):

Ammaji Rajala ◽

Raju V.S. Rajala

Keyword(s):

Insulin Receptor ◽

Signaling Pathway ◽

Receptor Signaling ◽

Retinal Photoreceptor ◽

Insulin Receptor Signaling ◽

Receptor Signaling Pathway ◽

Photoreceptor Neurons

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Selective loss of RPGRIP1-dependent ciliary targeting of NPHP4, RPGR and SDCCAG8 underlies the degeneration of photoreceptor neurons

Cell Death and Disease ◽

10.1038/cddis.2012.96 ◽

2012 ◽

Vol 3 (7) ◽

pp. e355-e355 ◽

Cited By ~ 27

Author(s):

H Patil ◽

N Tserentsoodol ◽

A Saha ◽

Y Hao ◽

M Webb ◽

...

Keyword(s):

Selective Loss ◽

Photoreceptor Neurons

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The Abl/Enabled signaling pathway regulates Golgi architecture in Drosophila photoreceptor neurons

Molecular Biology of the Cell ◽

10.1091/mbc.e14-02-0729 ◽

2014 ◽

Vol 25 (19) ◽

pp. 2993-3005 ◽

Cited By ~ 8

Author(s):

Ramakrishnan Kannan ◽

Irina Kuzina ◽

Stephen Wincovitch ◽

Stephanie H. Nowotarski ◽

Edward Giniger

Keyword(s):

Cell Signaling ◽

Signaling Pathway ◽

Protein Trafficking ◽

Adaptor Protein ◽

Loss Of Function ◽

Abl Tyrosine Kinase ◽

Upstream Regulator ◽

Basal Portion ◽

Photoreceptor Neurons ◽

Drosophila Photoreceptor

The Golgi apparatus is optimized separately in different tissues for efficient protein trafficking, but we know little of how cell signaling shapes this organelle. We now find that the Abl tyrosine kinase signaling pathway controls the architecture of the Golgi complex in Drosophila photoreceptor (PR) neurons. The Abl effector, Enabled (Ena), selectively labels the cis-Golgi in developing PRs. Overexpression or loss of function of Ena increases the number of cis- and trans-Golgi cisternae per cell, and Ena overexpression also redistributes Golgi to the most basal portion of the cell soma. Loss of Abl or its upstream regulator, the adaptor protein Disabled, lead to the same alterations of Golgi as does overexpression of Ena. The increase in Golgi number in Abl mutants arises in part from increased frequency of Golgi fission events and a decrease in fusions, as revealed by live imaging. Finally, we demonstrate that the effects of Abl signaling on Golgi are mediated via regulation of the actin cytoskeleton. Together, these data reveal a direct link between cell signaling and Golgi architecture. Moreover, they raise the possibility that some of the effects of Abl signaling may arise, in part, from alterations of protein trafficking and secretion.

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Retinal photoreceptor neurons and pinealocytes accumulate mRNA for interphotoreceptor retinoid-binding protein (IRBP)

FEBS Letters ◽

10.1016/0014-5793(86)81547-2 ◽

1986 ◽

Vol 208 (1) ◽

pp. 133-137 ◽

Cited By ~ 80

Author(s):

Theo van Veen ◽

Albine Katial ◽

Toshimichi Shinohara ◽

D.J. Barrett ◽

B. Wiggert ◽

...

Keyword(s):

Binding Protein ◽

Interphotoreceptor Retinoid Binding Protein ◽

Retinal Photoreceptor ◽

Photoreceptor Neurons

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Successful arrest of photoreceptor and vision loss expands the therapeutic window of retinal gene therapy to later stages of disease

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1509914112 ◽

2015 ◽

Vol 112 (43) ◽

pp. E5844-E5853 ◽

Cited By ~ 44

Author(s):

William A. Beltran ◽

Artur V. Cideciyan ◽

Simone Iwabe ◽

Malgorzata Swider ◽

Mychajlo S. Kosyk ◽

...

Keyword(s):

Gene Therapy ◽

Retinitis Pigmentosa ◽

Large Animal Model ◽

Therapeutic Window ◽

Large Animal ◽

Visual Behavior ◽

Rate Of Progression ◽

Photoreceptor Neurons ◽

Retinal Gene Therapy

Inherited retinal degenerations cause progressive loss of photoreceptor neurons with eventual blindness. Corrective or neuroprotective gene therapies under development could be delivered at a predegeneration stage to prevent the onset of disease, as well as at intermediate-degeneration stages to slow the rate of progression. Most preclinical gene therapy successes to date have been as predegeneration interventions. In many animal models, as well as in human studies, to date, retinal gene therapy administered well after the onset of degeneration was not able to modify the rate of progression even when successfully reversing dysfunction. We evaluated consequences of gene therapy delivered at intermediate stages of disease in a canine model of X-linked retinitis pigmentosa (XLRP) caused by a mutation in the Retinitis Pigmentosa GTPase Regulator (RPGR) gene. Spatiotemporal natural history of disease was defined and therapeutic dose selected based on predegeneration results. Then interventions were timed at earlier and later phases of intermediate-stage disease, and photoreceptor degeneration monitored with noninvasive imaging, electrophysiological function, and visual behavior for more than 2 y. All parameters showed substantial and significant arrest of the progressive time course of disease with treatment, which resulted in long-term improved retinal function and visual behavior compared with control eyes. Histology confirmed that the humanRPGRtransgene was stably expressed in photoreceptors and associated with improved structural preservation of rods, cones, and ON bipolar cells together with correction of opsin mislocalization. These findings in a clinically relevant large animal model demonstrate the long-term efficacy ofRPGRgene augmentation and substantially broaden the therapeutic window for intervention in patients withRPGR-XLRP.

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