Cellular inhibitor of apoptosis (cIAP1) is down-regulated during Retinal ganglion cell (RGC) maturation

lncRNA LINC00960 promotes apoptosis by sponging ubiquitin ligase Nrdp1-targeting miR-183-5p

<p indent="0mm">The ubiquitin ligase Nrdp1/RNF41 promotes the ubiquitin-dependent degradation of multiple important substrates, including BRUCE/BIRC6, a giant ubiquitin-conjugating enzyme inhibiting both apoptosis and autophagy. miR-183-5p is associated with various malignancies potentially by targeting dozens of genes. Here, we show that the lncRNA LINC00960 binds to the Nrdp1-targeting miR-183-5p and promotes apoptosis. Compared to other known miR-183-5p targets, Nrdp1 mRNA is among the few with top scores to complement miR-183-5p. miR-183-5p binds to the <sc>3'UTR</sc> of Nrdp1 mRNA and downregulates Nrdp1 at both the mRNA and protein levels. The miR-183-5p mimics inhibit DNA damage-induced apoptosis probably by upregulating BRUCE level, whereas the miR-183-5p inhibitor suppresses the effects of miR-183-5p. LINC00960 is the noncoding RNA with the highest score to complement miR-183-5p. LINC00960 overexpression reduces, but its knockdown increases, the level of miR-183-5p, whereas LINC00960 overexpression increases, but its knockdown decreases, the level of Nrdp1 and apoptosis. Importantly, the expression of LINC00960, which is associated with multiple types of tumors, positively correlates with that of Nrdp1 in several tumors but inversely correlates with that of miR-183-5p in multiple human tumor cell lines, as analysed by quantitative PCR. Thus, miR-183-5p downregulates Nrdp1 expression and inhibits apoptosis, whereas LINC00960 upregulates Nrdp1 and promotes apoptosis by inhibiting miR-183-5p. These results may provide new ideas for the prevention, diagnosis and treatment of apoptosis-related diseases, such as tumors and neurodegenerative diseases. </p>.

Profiles of Rho, Opn4, c-Fos, and Birc5 mRNA expression in Wistar rat retinas exposed to white or monochromatic light

Despite concern over potential retinal damage linked to exposure to light-emitting-diode (LED) light (particularly blue light), it remains unknown how exposure to low-intensity monochromatic LED light affects the expression of rhodopsin (Rho, a photopigment that mediates light-induced retinal degeneration), melanopsin (Opn4, a blue-light sensitive photopigment), c-Fos (associated with retinal damage/degeneration), and Birc5 (anti-apoptotic). This study investigated the mRNA expression profiles of these genes under exposure to white and monochromatic light (blue, red, green) in the retinas of albino rats under a cycle of 12 h of light and 12 h of darkness. In each group, 32 Wistar rats were exposed to one type of monochromatic-LED or white-fluorescent light for 7 day (150 lx). Retinal samples were taken for qPCR analysis and light and electron microscopy. Blue and green light exposure markedly decreased expression of Rho and Opn4 mRNA and increased expression of Birc5 and c-Fos mRNA (P < 0.05). In retinas from the blue-light group, loss and vesiculation of photoreceptor outer segments were visible, but not in retinas from the red-light and control group. Measurements of the photoreceptor inner and outer segments length revealed, that this length was significantly decreased in the blue- and green-light exposure groups (P < 0.02), but not in the red-light exposure group. Increased expression of Birc5 and decreased expression of Rho and Opn4 after exposure to blue and green light may be early responses that help to reduce light-induced retinal damage.

Caspases in retinal ganglion cell death and axon regeneration

Retinal ganglion cells (RGC) are terminally differentiated CNS neurons that possess limited endogenous regenerative capacity after injury and thus RGC death causes permanent visual loss. RGC die by caspase-dependent mechanisms, including apoptosis, during development, after ocular injury and in progressive degenerative diseases of the eye and optic nerve, such as glaucoma, anterior ischemic optic neuropathy, diabetic retinopathy and multiple sclerosis. Inhibition of caspases through genetic or pharmacological approaches can arrest the apoptotic cascade and protect a proportion of RGC. Novel findings have also highlighted a pyroptotic role of inflammatory caspases in RGC death. In this review, we discuss the molecular signalling mechanisms of apoptotic and inflammatory caspase responses in RGC specifically, their involvement in RGC degeneration and explore their potential as therapeutic targets.