bims-mideyd 2024-05-05 papers

Issue of 2024‒05‒05
four papers selected by
Rajalekshmy “Raji” Shyam, Indiana University Bloomington

Tissue Cell. 2024 Apr 16. pii: S0040-8166(24)00082-X. [Epub ahead of print]88 102381

CD200R promotes high glucose-induced oxidative stress and damage in human retinal pigment epithelial cells by activating the mTOR signaling pathway.

Yaguang Hu, Ting Wei, Shan Gao, Ning Gao, Li Chen, Qiaochu Cheng.

Diabetic retinopathy (DR) is established as the primary cause of visual impairment and preventable blindness, posing significant social and economic burdens on healthcare systems worldwide. Oxidative stress has been identified as a major contributor to DR, yet the precise role of the transmembrane glycoprotein CD200R in this context remains elusive. We studied human retinal pigment epithelia ARPE-19 cells to investigate the role of CD200R in high-glucose (HG) induced oxidative stress. Under HG conditions, we found a significant increase in CD200R expression in a time-dependent pattern. Conversely, knockdown of CD200R effectively alleviated oxidative stress and restored cell viability in HG-treated ARPE-19 cells, a phenomenon corroborated by the addition of a reactive oxygen species (ROS) scavenger. Exploration of the AKT/mTOR signaling pathway confirmed its mediating role regarding CD200R knockdown suppression of the expression of key proteins induced by HG conditions. Additionally, we found that the inhibition of mTOR signaling with Rapamycin effectively countered HG-induced oxidative stress in ARPE-19 cells, suggesting a promising therapeutic target against oxidative stress in the context of DR. This study establishes the crucial role of CD200R in HG-induced oxidative stress and identifies potential therapeutic avenues for the treatment of DR.

Keywords: AKT/mTOR signaling; CD200R; Diabetic retinopathy; Oxidative stress

DOI: https://doi.org/10.1016/j.tice.2024.102381

Invest Ophthalmol Vis Sci. 2024 Apr 01. 65(4): 43

CFH Haploinsufficiency and Complement Alterations in Early-Onset Macular Degeneration.

Rayne R Lim, Sharlene Shirali, Jessica Rowlan, Abbi L Engel, Marcos Nazario, Kelie Gonzalez, Aspen Tong, Jay Neitz, Maureen Neitz, Jennifer R Chao.

Purpose: Complement dysregulation is a key component in the pathogenesis of age-related macular degeneration (AMD) and related diseases such as early-onset macular drusen (EOMD). Although genetic variants of complement factor H (CFH) are associated with AMD risk, the impact of CFH and factor H-like protein 1 (FHL-1) expression on local complement activity in human retinal pigment epithelium (RPE) remains unclear.Methods: We identified a novel CFH variant in a family with EOMD and generated patient induced pluripotent stem cell (iPSC)-derived RPE cells. We assessed CFH and FHL-1 co-factor activity through C3b breakdown assays and measured complement activation by immunostaining for membrane attack complex (MAC) formation. Expression of CFH, FHL-1, local alternative pathway (AP) components, and regulators of complement activation (RCA) in EOMD RPE cells was determined by quantitative PCR, western blot, and immunostaining. Isogenic EOMD (cEOMD) RPE was generated using CRISPR/Cas9 gene editing.
Results: The CFH variant (c.351-2A>G) resulted in loss of CFH and FHL-1 expression and significantly reduced CFH and FHL-1 protein expression (∼50%) in EOMD iPSC RPE cells. These cells exhibited increased MAC deposition upon exposure to normal human serum. Under inflammatory or oxidative stress conditions, CFH and FHL-1 expression in EOMD RPE cells paralleled that of controls, whereas RCA expression, including MAC formation inhibitors, was elevated. CRISPR/Cas9 correction restored CFH/FHL-1 expression and mitigated alternative pathway complement activity in cEOMD RPE cells.
Conclusions: Identification of a novel CFH variant in patients with EOMD resulting in reduced CFH and FHL-1 and increased local complement activity in EOMD iPSC RPE supports the involvement of CFH haploinsufficiency in EOMD pathogenesis.

DOI: https://doi.org/10.1167/iovs.65.4.43

Sci Rep. 2024 May 02. 14(1): 10096

POU6F2, a risk factor for glaucoma, myopia and dyslexia, labels specific populations of retinal ganglion cells.

Fangyu Lin, Ying Li, Jiaxing Wang, Sandra Jardines, Rebecca King, Micah A Chrenek, Janey L Wiggs, Jeffrey H Boatright, Eldon E Geisert.

Pou6f2 is a genetic connection between central corneal thickness (CCT) in the mouse and a risk factor for developing primary open-angle glaucoma. POU6F2 is also a risk factor for several conditions in humans, including glaucoma, myopia, and dyslexia. Recent findings demonstrate that POU6F2-positive retinal ganglion cells (RGCs) comprise a number of RGC subtypes in the mouse, some of which also co-stain for Cdh6 and Hoxd10. These POU6F2-positive RGCs appear to be novel of ON-OFF directionally selective ganglion cells (ooDSGCs) that do not co-stain with CART or SATB2 (typical ooDSGCs markers). These POU6F2-positive cells are sensitive to damage caused by elevated intraocular pressure. In the DBA/2J mouse glaucoma model, heavily-labeled POU6F2 RGCs decrease by 73% at 8 months of age compared to only 22% loss of total RGCs (labeled with RBPMS). Additionally, Pou6f2-/- mice suffer a significant loss of acuity and spatial contrast sensitivity along with an 11.4% loss of total RGCs. In the rhesus macaque retina, POU6F2 labels the large parasol ganglion cells that form the magnocellular (M) pathway. The association of POU6F2 with the M-pathway may reveal in part its role in human glaucoma, myopia, and dyslexia.

Keywords: CART; Cdh6; DBA/2J; Dyslexia; Glaucoma; Hoxd10; Mouse; Myopia; ON–OFF directionally selective; Optic nerve crush; POU6F2; Retinal ganglion cell

DOI: https://doi.org/10.1038/s41598-024-60444-5

Dis Model Mech. 2024 Apr 01. pii: dmm050640. [Epub ahead of print]17(4):

HIF-1α-dependent upregulation of angiogenic factors by mechanical stimulation in retinal pigment epithelial cells.

Atsushige Ashimori, Fumiaki Higashijima, Tadahiko Ogata, Ayano Sakuma, Waka Hamada, Junki Sunada, Ren Aoki, Masanori Mikuni, Ken'ichiro Hayashi, Makiko Wakuta, Takuya Yoshimoto, Akira Minamoto, Ji-Ae Ko, Kazuhiro Kimura.

Mechanical stimulation as a mimic of drusen formation in the eye increases the expression of angiogenic factors in retinal pigment epithelial (RPE) cells, but the underlying molecular mechanisms remain unclear. We investigated and characterized the effects of mechanical stimulation on the expression of angiogenic factors in RPE cells both in vitro and in a mouse model. Mechanical stimulation increased the expression of vascular endothelial growth factor (VEGF, encoded by VEGFA) and other angiogenesis-related genes in cultured RPE1 cells. The presence of hypoxia-inducible factor 1α (HIF-1α, encoded by HIF1A) was also increased, and both knockdown of HIF-1α and treatment with the HIF-1α inhibitor CAY10585 attenuated the effect of mechanical stimulation on angiogenesis factor gene expression. Signaling by the tyrosine kinase SRC and p38 mitogen-activated protein kinase was involved in HIF-1α activation and consequent angiogenesis-related gene expression induced by mechanical stimulation. Our results suggest that SRC-p38 and HIF-1α signaling are involved in the upregulation of angiogenic factors in RPE cells by mechanical stimulation. Such in vivo suppression of upregulated expression of angiogenesis-related genes by pharmacological inhibitors of HIF-1α suggests a new potential approach to the treatment of age-related macular degeneration.

Keywords: Age-related macular degeneration; Angiogenesis; HIF-1α; Mechanotransduction; Retinal pigment epithelial cells

DOI: https://doi.org/10.1242/dmm.050640