bims-mideyd 2023-06-18 papers

Issue of 2023‒06‒18
three papers selected by
Rajalekshmy “Raji” Shyam, Indiana University Bloomington

Cell Commun Signal. 2023 Jun 14. 21(1): 134

Inhibiting HIF-1 signaling alleviates HTRA1-induced RPE senescence in retinal degeneration.

Wenchang Xu, Xinqi Liu, Wenjuan Han, Keling Wu, Minglei Zhao, Tingfang Mei, Bizhi Shang, Jinwen Wu, Jingyi Luo, Yuhua Lai, Boyu Yang, Yehong Zhuo, Lin Lu, Yizhi Liu, Xiao-Li Tian, Ling Zhao.

BACKGROUND: Age-related macular degeneration (AMD), characterized by the degeneration of retinal pigment epithelium (RPE) and photoreceptors, is the leading cause of irreversible vision impairment among the elderly. RPE senescence is an important contributor to AMD and has become a potential target for AMD therapy. HTRA1 is one of the most significant susceptibility genes in AMD, however, the correlation between HTRA1 and RPE senescence hasn't been investigated in the pathogenesis of AMD.METHODS: Western blotting and immunohistochemistry were used to detect HTRA1 expression in WT and transgenic mice overexpressing human HTRA1 (hHTRA1-Tg mice). RT-qPCR was used to detect the SASP in hHTRA1-Tg mice and ARPE-19 cells infected with HTRA1. TEM, SA-β-gal was used to detect the mitochondria and senescence in RPE. Retinal degeneration of mice was investigated by fundus photography, FFA, SD-OCT and ERG. The RNA-Seq dataset of ARPE-19 cells treated with adv-HTRA1 versus adv-NC were analyzed. Mitochondrial respiration and glycolytic capacity in ARPE-19 cells were measured using OCR and ECAR. Hypoxia of ARPE-19 cells was detected using EF5 Hypoxia Detection Kit. KC7F2 was used to reduce the HIF1α expression both in vitro and in vivo.
RESULTS: In our study, we found that RPE senescence was facilitated in hHTRA1-Tg mice. And hHTRA1-Tg mice became more susceptible to NaIO3 in the development of oxidative stress-induced retinal degeneration. Similarly, overexpression of HTRA1 in ARPE-19 cells accelerated cellular senescence. Our RNA-seq revealed an overlap between HTRA1-induced differentially expressed genes associated with aging and those involved in mitochondrial function and hypoxia response in ARPE-19 cells. HTRA1 overexpression in ARPE-19 cells impaired mitochondrial function and augmented glycolytic capacity. Importantly, upregulation of HTRA1 remarkably activated HIF-1 signaling, shown as promoting HIF1α expression which mainly located in the nucleus. HIF1α translation inhibitor KC7F2 significantly prevented HTRA1-induced cellular senescence in ARPE-19 cells, as well as improved the visual function in hHTRA1-Tg mice treated with NaIO3.
CONCLUSIONS: Our study showed elevated HTRA1 contributes to the pathogenesis of AMD by promoting cellular senescence in RPE through damaging mitochondrial function and activating HIF-1 signaling. It also pointed out that inhibition of HIF-1 signaling might serve as a potential therapeutic strategy for AMD. Video Abstract.

Keywords: Age-related macular degeneration; Cell senescence; HIF1α; HTRA1; Hypoxia; Retinal pigment epithelium

DOI: https://doi.org/10.1186/s12964-023-01138-9

J Adv Res. 2023 Jun 14. pii: S2090-1232(23)00167-4. [Epub ahead of print]

Inhibition of oxidative stress-induced epithelial-mesenchymal transition in retinal pigment epithelial cells of age-related macular degeneration model by suppressing ERK activation.

Ya-Chi Yang, Yueh Chien, Aliaksandr A Yarmishyn, Lee-Yieng Lim, Hao-Yu Tsai, Wen-Chuan Kuo, Ping-Hsing Tsai, Sheng-Hsien Yang, Shao-I Hong, Shih-Jen Chen, De-Kuang Hwang, Yi-Ping Yang, Shih-Hwa Chiou.

INTRODUCTION: Epithelial-mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells is related to the pathogenesis of various retinopathies including age-related macular degeneration (AMD). Oxidative stress is the major factor to induce degeneration of RPE cells and associated with the etiology of AMD.OBJECTIVES: Sodium iodate (NaIO3) generates intracellular reactive oxygen species (ROS) and is widely used to establish a model of AMD due to the selective induction of retinal degeneration. This study was performed to clarify the effects of multiple NaIO3-stimulated signaling pathways on EMT in RPE cells.
METHODS: The EMT characteristics in NaIO3-treated human ARPE-19 cells and RPE cells of mouse eyes were analyzed. Multiple oxidative stress-induced modulators were investigated and the effect of pre-treatment with Ca2+ chelator, extracellular signal-related kinase (ERK) inhibitor, or epidermal growth factor receptor (EGFR) inhibitor on NaIO3-induced EMT were determined. The efficacy of post-treatment with ERK inhibitor on the regulation of NaIO3-induced signaling pathways was dissected and its role in retinal thickness and morphology was evaluated by using histological cross-sections and spectral domain optical coherence tomography.
RESULTS: We found that NaIO3 induced EMT in ARPE-19 cells and in RPE cells of the mouse eyes. The intracellular ROS, Ca2+, endoplasmic reticulum (ER) stress marker, phospho-ERK, and phospho-EGFR were increased in NaIO3-stimulated cells. Our results showed that pre-treatment with Ca2+ chelator, ERK inhibitor, or EGFR inhibitor decreased NaIO3-induced EMT, interestingly, the inhibition of ERK displayed the most prominent effect. Furthermore, post-treatment with FR180204, a specific ERK inhibitor, reduced intracellular ROS and Ca2+ levels, downregulated phospho-EGFR and ER stress marker, attenuated EMT of RPE cells, and restored structural disorder of the retina induced by NaIO3.
CONCLUSIONS: ERK is a crucial regulator of multiple NaIO3-induced signaling pathways that coordinate EMT program in RPE cells. Inhibition of ERK may be a potential therapeutic strategy for the treatment of AMD.

Keywords: FR180204; Retinopathy; calcium signaling; epithelial growth factor receptor; extracellular signal-regulated kinase; reactive oxygen species

DOI: https://doi.org/10.1016/j.jare.2023.06.004

Cells. 2023 Jun 01. pii: 1528. [Epub ahead of print]12(11):

Corneal Edema in Inducible Slc4a11 Knockout Is Initiated by Mitochondrial Superoxide Induced Src Kinase Activation.

Diego G Ogando, Edward T Kim, Shimin Li, Joseph A Bonanno.

PURPOSE: Inducible Slc4a11 KO leads to corneal edema by disruption of the pump and barrier functions of the corneal endothelium (CE). The loss of Slc4a11 NH3-activated mitochondrial uncoupling leads to mitochondrial membrane potential hyperpolarization-induced oxidative stress. The goal of this study was to investigate the link between oxidative stress and the failure of pump and barrier functions and to test different approaches to revert the process.METHODS: Mice which were homozygous for Slc4a11 Flox and Estrogen receptor -Cre Recombinase fusion protein alleles at 8 weeks of age were fed Tamoxifen (Tm)-enriched chow (0.4 g/Kg) for 2 weeks, and controls were fed normal chow. During the initial 14 days, Slc4a11 expression, corneal thickness (CT), stromal [lactate], Na+-K+ ATPase activity, mitochondrial superoxide levels, expression of lactate transporters, and activity of key kinases were assessed. In addition, barrier function was assessed by fluorescein permeability, ZO-1 tight junction integrity, and cortical cytoskeleton F-actin morphology.
RESULTS: Tm induced a rapid decay in Slc4a11 expression that was 84% complete at 7 days and 96% complete at 14 days of treatment. Superoxide levels increased significantly by day 7; CT and fluorescein permeability by day 14. Tight junction ZO-1 distribution and the cortical cytoskeleton were disrupted at day 14, concomitant with decreased expression of Cldn1, yet with increased tyrosine phosphorylation. Stromal lactate increased by 60%, Na+-K+ ATPase activity decreased by 40%, and expression of lactate transporters MCT2 and MCT4 significantly decreased, but MCT1 was unchanged at 14 days. Src kinase was activated, but not Rock, PKCα, JNK, or P38Mapk. Mitochondrial antioxidant Visomitin (SkQ1, mitochondrial targeted antioxidant) and Src kinase inhibitor eCF506 significantly slowed the increase in CT, with concomitant decreased stromal lactate retention, improved barrier function, reduced Src activation and Cldn1 phosphorylation, and rescued MCT2 and MCT4 expression.
CONCLUSIONS: Slc4a11 KO-induced CE oxidative stress triggered increased Src kinase activity that resulted in perturbation of the pump components and barrier function of the CE.

Keywords: Slc4a11; Src kinase; Visomitin; barrier function; corneal endothelial dystrophy; lactate transporters; oxidative stress

DOI: https://doi.org/10.3390/cells12111528