Neuropsin (OPN5)-mediated photoentrainment of local circadian oscillators in mammalian retina and cornea.
Buhr Ethan D,Yue Wendy W S,Ren Xiaozhi,Jiang Zheng,Liao Hsi-Wen Rock,Mei Xue,Vemaraju Shruti,Nguyen Minh-Thanh,Reed Randall R,Lang Richard A,Yau King-Wai,Van Gelder Russell N
Proceedings of the National Academy of Sciences of the United States of America
The molecular circadian clocks in the mammalian retina are locally synchronized by environmental light cycles independent of the suprachiasmatic nuclei (SCN) in the brain. Unexpectedly, this entrainment does not require rods, cones, or melanopsin (OPN4), possibly suggesting the involvement of another retinal photopigment. Here, we show that the ex vivo mouse retinal rhythm is most sensitive to short-wavelength light but that this photoentrainment requires neither the short-wavelength-sensitive cone pigment [S-pigment or cone opsin (OPN1SW)] nor encephalopsin (OPN3). However, retinas lacking neuropsin (OPN5) fail to photoentrain, even though other visual functions appear largely normal. Initial evidence suggests that OPN5 is expressed in select retinal ganglion cells. Remarkably, the mouse corneal circadian rhythm is also photoentrainable ex vivo, and this photoentrainment likewise requires OPN5. Our findings reveal a light-sensing function for mammalian OPN5, until now an orphan opsin.
Hypoxia-inducible factor-1 drives annexin A2 system-mediated perivascular fibrin clearance in oxygen-induced retinopathy in mice.
Huang Bihui,Deora Arun B,He Kai-Li,Chen Kang,Sui Guangzhi,Jacovina Andrew T,Almeida Dena,Hong Peng,Burgman Paul,Hajjar Katherine A
Oxygen-induced retinopathy (OIR) is a well-characterized model for retinopathy of prematurity, a disorder that results from rapid microvascular proliferation after exposure of the retina to high oxygen levels. Here, we report that the proliferative phase of OIR requires transcriptional induction of the annexin A2 (A2) gene through the direct action of the hypoxia-inducible factor-1 complex. We show, in addition, that A2 stabilizes its binding partner, p11, and promotes OIR-related angiogenesis by enabling clearance of perivascular fibrin. Adenoviral-mediated restoration of A2 expression restores neovascularization in the oxygen-primed Anxa2(-/-) retina and reinstates plasmin generation and directed migration in cultured Anxa2(-/-) endothelial cells. Systemic depletion of fibrin repairs the neovascular response to high oxygen treatment in the Anxa2(-/-) retina, whereas inhibition of plasminogen activation dampens angiogenesis under the same conditions. These findings show that the A2 system enables retinal neoangiogenesis in OIR by enhancing perivascular activation of plasmin and remodeling of fibrin. These data suggest new potential approaches to retinal angiogenic disorders on the basis of modulation of perivascular fibrinolysis.