Inhibiting microRNA-144 potentiates Nrf2-dependent antioxidant signaling in RPE and protects against oxidative stress-induced outer retinal degeneration

Abstract

The retinal pigment epithelium (RPE) is consistently exposed to high levels of pro-oxidant and inflammatory stimuli. As such, under normal conditions the antioxidant machinery in the RPE cell is one of the most efficient in the entire body. However, antioxidant defense mechanisms are often impacted negatively by the process of aging and/or degenerative disease leaving RPE susceptible to damage which contributes to retinal dysfunction. Thus, understanding better the mechanisms governing antioxidant responses in RPE is critically important. Here, we evaluated the role of the redox sensitive microRNA miR-144 in regulation of antioxidant signaling in human and mouse RPE. In cultured human RPE, miR-144-3p and miR-144-5p expression was upregulated in response to pro-oxidant stimuli. Likewise, overexpression of miR-144-3p and -5p using targeted miR mimics was associated with reduced expression of Nrf2 and downstream antioxidant target genes (NQO1 and GCLC), reduced levels of glutathione and increased RPE cell death. Alternately, some protection was conferred against the above when miR-144-3p and miR-144-5p expression was suppressed using antagomirs. Expression analyses revealed a higher conservation of miR-144-3p expression across species and additionally, the presence of two potential Nrf2 binding sites in the 3p sequence compared to only one in the 5p sequence. Thus, we evaluated the impact of miR-144-3p expression in the retinas of mice in which a robust pro-oxidant environment was generated using sodium iodate (SI). Subretinal injection of miR-144-3p antagomir in SI mice preserved retinal integrity and function, decreased oxidative stress, limited apoptosis and enhanced antioxidant gene expression. Collectively, the present work establishes miR-144 as a potential target for preventing and treating degenerative retinal diseases in which oxidative stress is paramount and RPE is prominently affected (e.g., age-related macular degeneration and diabetic retinopathy).

The Role of microRNAs in Metabolic Syndrome-Related Oxidative Stress

“…Both miRNAs were shown to target 3 UTR of Nrf2, yet, only the impact of miR-144-3p was studied using antagomir-based approach and subretinal injection in mice retinas. As expected, downregulation of miR-144-3p exerted an antioxidative impact along with decreased apoptosis and increased retinal function and integrity [258]. Nrf2 is also targeted by miR-93 upon HG in retinal cells due to downregulation of lncRNA MEG3, a direct regulator of miR-93 [259].…”

“…HG-mediated apoptosis of RPE cells was reported to be, at least partially, accomplished via induction of miR-383, followed by reduction of expression of its direct target, PRDX3, an antioxidant enzyme [257]. A recent study by Jadeja et al showed that RPE cells-specific miR-144-3p and -5p are subjected to upregulation upon prooxidant stimulation (one typically occurring in diabetic retinopathy or age-related degeneration), being connected with declined levels of Nrf2 and antioxidant genes (GR, GCLC, NQO1) [258]. Both miRNAs were shown to target 3 UTR of Nrf2, yet, only the impact of miR-144-3p was studied using antagomir-based approach and subretinal injection in mice retinas.…”

Data on the role of miR-144 in regulating fetal hemoglobin production in retinal pigmented epithelial cells

“…However, the data in this article is the first documentation of miR-144 upregulation in the retinal pigment epithelium (RPE) of a humanized mouse model of sickle cell disease.The data set on the involvement of miR-144 in regulating fetal hemoglobin is highly important for further research on sickle cell retinopathy. Based on these data, miR-144 levels may be used as a potential diagnostic marker to predict occurrence of retinopathy in patients with sickle cell disease.Further, this data in combination with our recent report [1] shows that inhibiting miR-144 expression could improve fetal hemoglobin production and limit oxidative stress in RPE thereby, providing an effective avenue to prevent and treat retinopathy characteristic of sickle cell and other degenerative retinal diseases.…”

“…Inhibiting microRNA-144 potentiates Nrf2-dependent antioxidant signaling in RPE and protects against oxidative stress-induced outer retinal degeneration, Redox Biology 28 (2020) 101336. [1]…”

Potential Protective and Therapeutic Roles of the Nrf2 Pathway in Ocular Diseases: An Update

“…Attenuates UV-induced oxidative stress via activating Keap1-Nrf2 signaling [183] miR-144 RPEs Inhibiting microRNA-144 potentiates Nrf2-dependent antioxidant signaling and protects against OS-induced outer retinal degeneration [184] miR-626 RPEs Ectopic overexpression of miR-626 targeting the 3′-UTR (3′-untranslated region) of Keap1 downregulates its expression, promoting Nrf2 protein stabilization and nuclear translocation, leading to the expression of HO-1, NOQ1, and GCLC [185] miR-601…”