Ghrelin inhibits autophagy mediated by AKT/mTOR pathway to ameliorate retinal angiogenesis induced by high glucose stress.

AIM: To observe the effect of ghrelin, a growth hormone-releasing peptide, on retinal angiogenesis in vitro under high glucose (HG) stress and to explore the possible mechanism of autophagy. METHODS: Human retinal microvascular endothelial cells (HRMECs) were treated with high concentration of glucose alone or in combination with ghrelin. The cell migration, tube formation and the expression of the autophagy-related proteins LC3-II/I, Beclin-1, p62, phosphorylated AKT (p-AKT)/AKT and phosphorylated mammalian target of rapamycin (p-mTOR)/mTOR were detected. Then, to clarify the correlation between ghrelin effect and autophagy, AKT inhibitor VIII was adopted to treat HRMECs, and cell migration, tube formation as well as the protein expressions of LC3-II/I, Beclin-1 and p62 were observed. RESULTS: Under HG stress, ghrelin inhibited migration and tube formation of HRMECs. Ghrelin inhibited the increases in the protein levels of LC3-II/I, Beclin-1 and the decreases in the protein levels of p62, p-AKT/AKT and p-mTOR/mTOR induced by HG stress. Moreover, under the action of AKT/mTOR pathway inhibitors, the effects of ghrelin on migration and tube formation were both reduced. In addition, the expression of LC3-II/I and Beclin-1 were significantly up-regulated and the expression of p62 was down-regulated. CONCLUSION: Retinal angiogenesis under in vitro HG stress can be inhibited by ghrelin through activating AKT/mTOR pathway to inhibit autophagy.

Rhodamine-based 'turn-on' fluorescent probe for Cu(II) and its fluorescence imaging in living cells.

A novel rhodamine spirolactam derivative 3',6'-Bis(diethylamino)-2-(2-hydroxyethylamino) spiro[isoindoline-1,9'-xanthen]-3-one (RO1) was synthesized, and characterized by high-resolution mass spectrometry (HRMS), X-ray crystallography, Infrared spectroscopy (IR), and (1)H NMR and (13)C NMR spectroscopy. RO1 exhibited highly sensitive and exclusively selective fluorescence response toward Cu(2+) over other metal ions with a detection limit of 0.56ppb in mixed aqueous solution. The fluorescence was pH-independent in the wide range pH 3.1-11.6. The turn-on fluorescence enhancement of the probe is based on Cu(2+) induced ring-opening mechanism of the rhodamine spirolactam. Moreover, by means of fluorescence microscopy experiments, it was demonstrated that RO1 could monitor trace Cu(2+) changes by live cell imaging.

Rac1 activates HIF-1 in laser induced choroidal neovascularization.

AIM: To study the effect of Rac1 on the induction of HIF-1α in choroidal neovascularization (CNV) in mice. METHODS: One hundred C57BL/6J mice were laser photocoagulated to induce CNV, fifty mice of that were selected randomly for intravitreal injection of Rac1 inhibitor NSC23766 solution (1µL). After laser photocoagulation, fundus fluorescein angiography (FFA) was performed to verify the growth of CNV, Immunohistochemistry and Western blot were used to detect HIF-1α and Rac1 in posterior segment of eye globes. RESULTS: FFA verified that incidence of CNV was significantly reduced in the eyes with NSC23766 injection comparing with that of eyes without NSC23766 injection (P<0.01). Immunohistochemistry detected that HIF-1α and Rac1 mainly expressing in the new fibrovascular tissue. Western blot showed that HIF-1α and Rac1 was highly increased in tissue explants of retinal pigment epithelium (RPE) and choroid without NSC23766 injection. But for tissue explants of RPE and choroid with NSC23766 injection, both the expression of HIF-1α and Rac1 were inhibited. CONCLUSION: Rac1 is crucial to activate HIF-1 regulating the growth of CNV, and its inhibition may have potential therapeutic value.

[(2-{[3',6'-Bis(ethyl-amino)-2',7'-dimethyl-3-oxospiro-[1H-isoindole-1,9'-9H-xanthen]-2-yl}eth-yl)amino-meth-yl]phenol.

The title compound, C(35)H(38)N(4)O(3), was prepared as a spiro-lactam ring formation of rhodamine dye for comparison with a ring-opened form. The xanthene ring system is approximately planar. The dihedral angles formed by the spiro-lactam and phenol rings with the xanthene ring system are 85.7 and 109.4°, respectively. Each of the mol-ecules in the crystal structure contains one intra-molecular O-H⋯N hydrogen bond, and they form inter-molecular N-H⋯O hydrogen-bonded chains along the [100] direction. Weak inter-molecular C-H⋯O hydrogen-bonding contacts connect the infinite chains via crystallographic inversion centres to form a two-dimensional network.

Erratum: [(2-{[3',6'-Bis(ethyl-amino)-2',7'-dimethyl-3-oxospiro-[1H-isoindole-1,9'-9H-xanthen]-2-yl}eth-yl)amino-meth-yl]phenol. Corrigendum.

The title and the chemical diagram of the paper by Zhang, Peng, Gao & Fan [Acta Cryst. (2008), E64, o403] are corrected.[This corrects the article DOI: 10.1107/S1600536807055559.].