Biology subjects

Moshiri, A.

Publications and source records attributed to Moshiri, A..

4 recordsLinked to original sources

bioRxiv2021

Arap1 Loss Causes RPE Phagocytic Dysfunction and Subsequent Photoreceptor Death

PurposeArap1 is an Arf-directed GTPase-activating protein (GAP) shown to modulate actin cytoskeletal dynamics by regulating Arf and Rho family members. We have previously shown that Arap1-/- mice develop photoreceptor degeneration similar to the human condition retinitis pigmentosa (RP), corroborated by fundus examination, histopathology, and ERG analysis. However, Arap1 expression was not detected in photoreceptors, but in Muller Glia and retinal pigment epithelium (RPE), suggesting a non-cell-autonomous mechanism for degeneration. The aim of this study was to elucidate the role of retinal Arap1 in photoreceptor maintenance. MethodsAlbino Arap1-/- mice were generated via breeding pigmented Arap1-/- mice onto a Tyr-/- C57BL/6J background. Conditional knockout (cKO) mice were generated for Muller Glia/RPE, Muller Glia, and RPE via targeting Cralbp, Glast, and Vmd2 promoters, respectively, to drive Cre recombinase expression to knock out Arap1. Mice were analyzed by fundus photography, optical coherence tomography (OCT), histology, and immunohistochemistry. Arap1 binding partners were assayed by affinity purification mass spectrometry. ResultsVmd2-Cre Arap1tm1c/tm1c and Cralbp-Cre Arap1tm1c/tm1c mice, but not Glast-Cre Arap1tm1c/tm1c mice, recapitulated the photoreceptor degeneration phenotype originally observed in germline Arap1-/- mice. These findings were corroborated by fundus exam, OCT, and histological analysis. Mass spectrometry analysis of ARAP1 co-immunoprecipitation identified putative binding partners of ARAP1, revealing numerous interactants involved in phagocytosis, cytoskeletal composition, intracellular trafficking, and endocytosis. Quantification of rod outer segment (OS) phagocytosis in vivo demonstrated a clear phagocytic defect in Arap1-/- mice compared to Arap1+/+ littermate controls while cone phagocytosis was preserved. ConclusionsArap1 expression, specifically in RPE, is necessary for photoreceptor survival due to its indispensable function in RPE phagocytosis. We propose a model in which Arap1 regulates G-protein function for nonmuscle myosin II targeting during phagocytosis. This novel role of Arap1 is important for further understanding of both the diversity of its functions and the complex molecular regulation of RPE phagocytosis.

molecular biology↗

bioRxiv2021

Age-Related Changes in the Rhesus Macaque Eye

PurposeTo assess age-related changes in the rhesus macaque eye and evaluate them to corresponding human age-related eye disease. MethodsData from eye exams and imaging tests including intraocular pressure (IOP), lens thickness, axial length, and retinal optical coherence tomography (OCT) images were evaluated from 142 individuals and statistically analyzed for age-related changes. Quantitative autofluorescence (qAF) was measured as was the presence of macular lesions as related to age. ResultsAges of the 142 rhesus macaques ranged from 0.7 to 29 years (mean=16.4 years, stdev=7.5 years). Anterior segment measurements such as IOP, lens thickness, and axial length were acquired. Advanced retinal imaging in the form of optical coherence tomography and qAF were obtained. Quantitative assessments were made and variations by age groups were analyzed to compare with established age-related changes in human eyes. Quantitative analysis of data revealed age-related increase in intraocular pressure, ocular biometry (lens thickness and axial length), and presence of macular lesions. Age-related changes in thicknesses of retinal layers on OCT were observed and quantified. Age was correlated with increased qAF. ConclusionsThe rhesus macaque has age-related ocular changes similar to humans. IOP increases with age while retinal ganglion cell layer thickness decreases. Macular lesions develop in some aged animals. Our findings support the concept that rhesus macaques may be useful for the study of important age-related diseases such as glaucoma, macular diseases, and cone disorders, and for development of therapies for these diseases.

systems biology↗

bioRxiv2021

Retinal organoids derived from rhesus macaque iPSCs undergo accelerated differentiation compared to human stem cells

PurposeTo compare the timing and efficiency of the development of non-human primate (NHP) derived retinal organoids in comparison to those derived from human embryonic stem cells. MethodsHuman embryonic stem cells (hESCs) and induced-pluripotent stem cells (rhiPSCs) derived from non-human primates (Macaca mulatta) were differentiated into retinal organoids by using an established differentiation protocol. Briefly, embryoid bodies were formed from pluripotent stem cells and induced into a neural lineage with neural induction media with the addition of BMP4. Thereafter, self-formation of optic vesicles was allowed to form in a 2D culture in retinal differentiation media (RDM). Optic vesicles were then manually harvested and cultured in suspension in 3D-RDM media until analysis. Differences in the timing of differentiation and efficiency of retinal organoid development were assessed by light microscopy, electron microscopy, immunocytochemistry, and single-cell transcriptomics. ResultsGeneration of retinal organoids was achieved from both human and several NHP pluripotent stem cells lines. All rhiPSC lines resulted in retinal differentiation with the formation of optic vesicle-like structures similar to what has been observed in hESC retinal organoids. NHP retinal organoids had laminated structure and were composed of mature retinal cell types including cone and rod photoreceptors. Single cell RNA sequencing was conducted at two time points, which allowed identification of cell types and characterization of developmental trajectory in the developing organoid. Important differences between rhesus and human cells were measured regarding the timing and efficiency of retinal organoid differentiation. While the culture of NHP-derived iPSCs is relatively difficult compared to human stem cells, the generation of retinal organoids is feasible and may be less time consuming due to an intrinsically faster timing of retinal differentiation. ConclusionsRetinal organoids produced from iPSCs derived from Rhesus monkey using established protocols differentiate through the stages of organoid development faster than those derived from human stem cells. The production of NHP retinal organoids may be advantageous to reduce experimental time and cost for basic biology studies in retinogenesis as well as for preclinical trials in NHPs studying retinal allograft transplantation.

cell biology↗

bioRxiv2020

Advanced Retinal Imaging and Ocular Parameters of the Rhesus Macaque Eye

PurposeTo determine the normal ocular biometric and perform advanced retinal imaging and functional assessment of a non-human primate used commonly in scientific research, the rhesus macaque. MethodsWe performed ocular phenotyping on rhesus macaques at the California National Primate Research Center. This consisted of anterior and posterior segment eye examination by ophthalmologists, advanced retinal imaging, and functional retinal electrophysiology. ResultsFull eye exams were performed on 142 animals consisting of pupillary light reflex, tonometry, external exam and photography, anterior slit lamp examination, and posterior segment examination by indirect ophthalmoscopy. Ages of the rhesus macaques ranged from 0.7 to 29 years (mean=16.4 years, stdev=7.5 years). Anterior segment measurements such as intraocular pressure (n=142), corneal thickness (n=84), lens thickness (n=114), and axial length (n=114) were acquired. Advanced retinal imaging in the form of fundus photography (n=78), optical coherence tomography (n=60), and quantitative autofluorescence (n=44) were obtained. Electroretinography (n=75) was used to assay retinal function. Quantitative analyses of macular structure, retinal layer segmentation, and rod and cone photoreceptor electrical responses are reported. Quantitative assessments were made and variations between genders and age groups were analyzed to compare with established sex and age-related changes in human eyes. ConclusionsThe rhesus macaque has ocular structure and function very similar to that of the human eye. Age-related ocular changes between rhesus and humans are similar. In particular, macular structure and function are very similar to humans making this species particularly useful for the study of macular biology and development of therapies for inherited and age-related macular degenerations as well as cone photoreceptor disorders.

physiology↗