Structural role of the T94I rhodopsin mutation in congenital stationary night blindness

Congenital stationary night blindness (CSNB) is an inherited and non‐progressive retinal dysfunction. Here, we present the crystal structure of CSNB‐causing T94I^2.61 rhodopsin in the active conformation at 2.3 Å resolution. The introduced hydrophobic side chain prolongs the lifetime of the G protein activating metarhodopsin‐II state by establishing a direct van der Waals contact with K296^7.43, the site of retinal attachment. This is in stark contrast to the light‐activated state of the CSNB‐causing G90D^2.57 mutation, where the charged mutation forms a salt bridge with K296^7.43. To find the common denominator between these two functional modifications, we combined our structural data with a kinetic biochemical analysis and molecular dynamics simulations. Our results indicate that both the charged G90D^2.57 and the hydrophobic T94I^2.61 mutation alter the dark state by weakening the interaction between the Schiff base (SB) and its counterion E113^3.28. We propose that this interference with the tight regulation of the dim light photoreceptor rhodopsin increases background noise in the visual system and causes the loss of night vision characteristic for CSNB patients.     

Neuroprotective effects of (E)-3,4-diacetoxystyryl sulfone and sulfoxide derivatives in vitro models of Parkinson's disease

(E)-3,4-dihydroxystyryl aralkyl sulfones and sulfoxides have been reported as novel multifunctional neuroprotective agents in previous studies, which as phenolic compounds display antioxidative and antineuroinflammatory properties. To further enhance the neuroprotective effects and study structure-activity relationship of the derivatives, we synthesized their acetylated derivatives, (E)-3,4-diacetoxystyryl sulfones and sulfoxides, and examined their neuroprotective effects in vitro models of Parkinson’s disease. The results indicate that (E)-3,4-diacetoxystyryl sulfones and sulfoxides can significantly inhibit kinds of neuron cell injury induced by toxicities, including 6-OHDA, NO, and H₂O₂. More important, they show higher antineuroinflammatory properties and similar antioxidative properties to corresponding un-acetylated compounds. Thus, we suggest that (E)-3,4-diacetoxystyryl sulfones and sulfoxides may have potential for the treatment of neurodegenerative disorders, especially Parkinson’s disease.     

Pou4f2‐GFP knock‐in mouse line: A model for studying retinal ganglion cell development

Pou4f2 acts as a key node in the comprehensive and step‐wise gene regulatory network (GRN) and regulates the development of retinal ganglion cells (RGCs). Accordingly, deletion of Pou4f2 results in RGC axon defects and apoptosis. To investigate the GRN involved in RGC regeneration, we generated a mouse line with a POU4F2‐green fluorescent protein (GFP) fusion protein expressed in RGCs. Co‐localization of POU4F2 and GFP in the retina and brain of Pou4f2‐GFP/+ heterozygote mice was confirmed using immunofluorescence analysis. Compared with those in wild‐type mice, the expression patterns of POU4F2 and POU4F1 and the co‐expression patterns of ISL1 and POU4F2 were unaffected in Pou4f2‐GFP/GFP homozygote mice. Moreover, the quantification of RGCs showed no significant difference between Pou4f2‐GFP/GFP homozygote and wild‐type mice. These results demonstrated that the development of RGCs in Pou4f2‐GFP/GFP homozygote mice was the same as in wild‐type mice. Thus, the present Pou4f2‐GFP knock‐in mouse line is a useful tool for further studies on the differentiation and regeneration of RGCs.     

Amino acids essential for the interaction between cellular heat shock protein 90 and a Kaposi’s sarcoma-associated herpesvirus-encoded protein kinase ORF36

Electronic Supplementary MaterialSupplementary material is available for this article at 10.1007/s12250-016-3839-9 and is accessible for authorized users.     

Hmgn5 functions downstream of Hoxa10 to regulate uterine decidualization in mice

Although Hmgn5 is involved in the regulation of cellular proliferation and differentiation, its physiological function during decidualization is still unknown. Here we showed that Hmgn5 was highly expressed in the decidual cells. Silencing of Hmgn5 expression by specific siRNA reduced the proliferation of uterine stromal cells and expression of Ccnd3 and Cdk4 in the absence or presence of estrogen and progesterone, whereas overexpression of Hmgn5 exhibited the opposite effects. Simultaneously, Hmgn5 might induce the expression of Prl8a2 and Prl3c1 which were 2 well-known differentiation markers for decidualization. In the uterine stromal cells, cAMP analog 8-Br-cAMP and progesterone could up-regulate the expression of Hmgn5, but the up-regulation was impeded by H89 and RU486, respectively. Attenuation of Hmgn5 expression could block the differentiation of uterine stromal cells in response to cAMP and progesterone. Further studies found that regulation of cAMP and progesterone on Hmgn5 expression was mediated by Hoxa10. During in vitro decidualization, knockdown of Hmgn5 could abrogate Hoxa10-induced upregulation of Prl8a2 and Prl3c1, while overexpression of Hmgn5 reversed the inhibitory effects of Hoxa10 siRNA on the expression of Prl8a2 and Prl3c1. In the stromal cells undergoing decidualization, Hmgn5 might act downstream of Hoxa10 to regulate the expression of Cox-2, Vegf and Mmp2. Collectively, Hmgn5 may play an important role during mouse decidualization.