High glucose-induced ROS accumulation is a critical regulator of ERK1/2-Akt-tuberin-mTOR signalling in RGC-5 cells. Pal Sweta,Rao G Nageswar,Pal Arttatrana Life sciences Hyperglycemia and oxidative stress are the primary stressors that elicit mitochondria specific cell stress in diabetes. Here we hypothesized that elevated level of ROS in high glucose (HG) environment, trigger mitochondrial stress by damaging mitochondrial DNA (mtDNA), altering inflammatory mediators, and neurodegenerative markers via stress signalling pathway in retinal ganglion cells (RGC-5). Mechanistically, our findings illustrated that the HG environment increases the ROS production in retinal cells leading to the disruption of antioxidant defence mechanism, and altering mitochondrial machinery such as an increase in loss of mitochondrial membrane potential (ΔΨm), increase in mitochondrial mass, and increase in mtDNA fragmentation. Furthermore, fragmented mtDNA escape from mitochondria into the cytosol, where it engaged with cyclic GMP-AMP synthase (cGAS) and stimulator of IFN gene (STING) phosphorylation and activate interferon regulatory factor 3 (IRF3) via ERK1/2-Akt-tuberin-mTOR dependent pathways. Our results further indicate that siRNA-mediated gene silencing of tuberin suppresses the strong downregulation of tuberin-mTOR-IRF3 activation. HG environment resulted in activation of IRF3, coinciding with the increased expression of inflammatory mediators and neurodegenerative markers. Pre-treatment of N-acetyl-l-cysteine (NAC) or ERK1/2 or phosphoinositide3-kinase (PI3-K)/Akt inhibitors in RGC-5 cells significantly reduced the HG-induced IRF3 expression and declined the expression of neurodegenerative markers. Collectively, our results demonstrates that HG-induced over production of ROS, disrupts the antioxidant defence mechanism and mitochondrial dysfunction, leading to alterations of inflammatory mediators and neurodegenerative markers through the ERK1/2-Akt-tuberin-mTOR dependent signalling pathway in RGC-5 cells. 10.1016/j.lfs.2020.117914

GLCCI1 alleviates GRP78-initiated endoplasmic reticulum stress-induced apoptosis of retinal ganglion cells in diabetic retinopathy by upregulating and interacting with HSP90AB1. Scientific reports Retinal ganglion cells (RGCs) are among the first neurons to undergo apoptosis in diabetic retinopathy (DR), with their relationship to endoplasmic reticulum stress (ERS)-induced apoptosis still unclear. While glucocorticoid-induced transcript 1 (GLCCI1) has been shown to inhibit apoptosis, its role in ERS-induced apoptosis and its mechanisms in DR remain unclarified. Our findings indicated that GLCCI1 is predominantly localized in the ganglion cell layer and is downregulated in DR. GLCCI1 overexpression mitigated the apoptosis of RGCs and the swelling of endoplasmic reticulum and mitochondria under hyperglycemia, and downregulated ERS-induced apoptosis related markers (GRP78, CHOP and cleaved CASP3), whereas GLCCI1 knockdown has the opposite effect. In vivo, GLCCI1 overexpression not only prevents structural lesions but also protects against microvascular dysfunctions in the retinas of DR mice. We found that GLCCI1 directly interacts with HSP90AB1, which in turn interacts with GRP78. Additionally, GLCCI1 is an upstream regulator of HSP90AB1, which regulates GRP78. Thus, the impact of GLCCI1 on the ERS-induced apoptosis is mainly through the regulation of HSP90AB1, and subsequently inhibiting GRP78-initiated ERS-induced apoptosis. These findings offer a promising avenue for further treatment of DR. 10.1038/s41598-024-75874-4

Diterpene Ginkgolides Meglumine Injection inhibits apoptosis induced by optic nerve crush injury via modulating MAPKs signaling pathways in retinal ganglion cells. Fan Xiao-Xue,Cao Ze-Yu,Liu Min-Xuan,Liu Wen-Jun,Xu Zhi-Liang,Tu Peng-Fei,Wang Zhen-Zhong,Cao Liang,Xiao Wei Journal of ethnopharmacology ETHNOPHARMACOLOGICAL RELEVANCE:Diterpene Ginkgolides Meglumine Injection (DGMI) is made of extracts from Ginkgo biloba L, including Ginkgolides A, B, and K and some other contents, and has been widely used as the treatment of cerebral ischemic stroke in clinic. It can be learned from the "Compendium of Materia Medica" that Ginkgo possesses the effect of "dispersing toxin". The ancient Chinese phrase "dispersing toxin" is now explained as elimination of inflammation and oxidative state in human body. And it led to the original ideas for today's anti-oxidation studies of Ginkgo in apoptosis induced by optic nerve crush injury. AIM OF THE STUDY:To investigate the underlying molecular mechanism of the DGMI in retinal ganglion cells (RGCs) apoptosis. MATERIALS AND METHODS:TUNEL staining was used to observe the anti-apoptotic effects of DGMI on the adult rat optic nerve injury (ONC) model, and flow cytometry and hoechst 33,342 staining were used to observe the anti-apoptotic effects of DGMI on the oxygen glucose deprivation (OGD) induced RGC-5 cells injury model. The regulation of apoptosis and MAPKs pathways were investigated with Immunohistochemistry and Western blotting. RESULTS:This study demonstrated that DGMI is able to decrease the conduction time of F-VEP and ameliorate histological features induced by optic nerve crush injury in rats. Immunohistochemistry and TUNEL staining results indicated that DGMI can also inhibit cell apoptosis via modulating MAPKs signaling pathways. In addition, treatment with DGMI markedly improved the morphological structures and decreased the apoptotic index in RGC-5 cells. Mechanistically, DGMI could significantly inhibit cell apoptosis by inhibiting p38, JNK and Erk1/2 activation. CONCLUSION:The study shows that DGMI and ginkgolides inhibit RGCs apoptosis by impeding the activation of MAPKs signaling pathways in vivo and in vitro. Therefore, the present study provided scientific evidence for the underlying mechanism of DGMI and ginkgolides on optic nerve crush injury. 10.1016/j.jep.2021.114371

Dendrobium nobile protects retinal cells from UV-induced oxidative stress damage via Nrf2/HO-1 and MAPK pathways. Hsu Wei-Hsiang,Chung Cheng-Pei,Wang Yi-Yueh,Kuo Yueh-Hsiung,Yeh Chih-Hsin,Lee I-Jung,Lin Yun-Lian Journal of ethnopharmacology ETHNOPHARMACOLOGICAL RELEVANCE:Excessive UV irradiation and ROS exposure are the main contributors of ocular pathologies. Pseudobulb of Dendrobium nobile Lindl. is one of the sources of Shihu and has long been used in traditional Chinese medicine as a tonic to nourish stomach, replenish body fluid, antipyretic and anti-inflammation. AIM OF STUDY:This study aimed to investigate whether D. nobile could protect ocular cells against oxidative stress damage. MATERIALS AND METHODS:Retinal-related cell lines, ARPE-19 and RGC-5 cells, were pretreated with D. nobile extracts before HO- and UV-treatment. Cell viability and the oxidative stress were monitored by sulforhodamine B (SRB) and SOD1 and CAT assay kits, respectively. The oxidative stress related proteins were measured by Western blotting. RESULTS:Under activity-guided fractionation, a sesquiterpene-enriched fraction (DN-2) and a major component (1) could ameliorate HO- and UV-induced cytotoxicity and SOD1 and CAT activity, but not dendrobine, the chemical marker of D. nobile. Western blotting showed both DN-2 and compound 1 protected ARPE-19 cells against UV-induced oxidative stress damage by regulating MAPK and Nrf2/HO-1 signaling. CONCLUSION:Our results suggest D. nobile extract protects retinal pigment epithelia cells from UV- and oxidative stress-damage, which may have a beneficial effect on eye diseases. 10.1016/j.jep.2021.114886