Identification of connexin43 in diabetic retinopathy and its downregulation by O-GlcNAcylation to inhibit the activation of glial cells

BackgroundDespite advances in the treatments of diabetic complications, proliferative diabetic retinopathy (PDR) still remains a major cause leading to visual loss, mainly because of the lack of pathological mechanisms and complicated protein expressions in vivo. Current study aimed to investigate the patterns of connexin43 (Cx43) changes and the possible interactions with O-GlcNAcylation in DR.MethodsClinical samples of vitreous and fibrovascular membranes were acquired from PDR patients during pars plana vitrectomy. Brown Norway rats were used to build diabetic animal models; to investigate the effects of O-GlcNAcylation on Cx43 expressions, total retinal O-GlcNAcylation was changed by intravitreal injections. Levels of protein expressions were examined by immunofluorescence staining and western blot.ResultsOur results revealed increased Cx43 expressions in a vessel-shape pattern followed by the distribution of glial fibrillary acidic protein (GFAP) in diabetic fibrovascular membranes. Similarly, Cx43 and GFAP expressions were elevated in PDR vitreous and diabetic animal retinas. Retinal O-GlcNAcylation was effectively regulated by intravitreal injections, and the increase of Cx43 and GFAP was significantly suppressed by O-GlcNAcylation inhibition under hyperglycemia conditions.ConclusionsWe systemically proved the changes of Cx43 with different retinal cells, and reported the effective methods to regulate retinal O-GlcNAcylation by intravitreal injections, and clearly illustrated the downregulated effects of O-GlcNAcylation inhibition on Cx43 and GFAP expressions.General significance:Targeting connexin43 in glial cells reveals a novel mechanism to understand the formation of diabetic fibrovascular membranes and offers a potential therapeutic strategy to interfere the development of PDR.     

Targeting ubiquitin specific protease 7 in cancer: A deubiquitinase with great prospects

Deubiquitinase (DUB)‐mediated cleavage of ubiquitin chain balances ubiquitination and deubiquitination for determining protein fate. USP7 is one of the best characterized DUBs and functionally important. Numerous proteins have been identified as potential substrates and binding partners of USP7; those play crucial roles in diverse array of cellular and biological processes including tumour suppression, cell cycle, DNA repair, chromatin remodelling, and epigenetic regulation. This review aims at summarizing the current knowledge of this wide association of USP7 with many cellular processes that enlightens the possibility of abnormal USP7 activity in promoting oncogenesis and the importance of identification of specific inhibitors.     

Emodin-Induced Necroptosis in Prostate Cancer Cells via the Mitochondrial Fission HSP90/MLKL/PGAM Pathway

Currently, prostate cancer is one of the major malignant tumors in males. Recurrence and metastasis are the main obstacles that prevent the effective treatment of prostate cancer. In the present study, we aimed to evaluate emodin (EG) against human prostate cancer PC3 and DU145 cells. Our study showed that EG significantly decreased the cell viability of PC3 and DU145 cells and strikingly induced non-apoptotic cell death via necroptosis that was visualized through colony formation assay, Hoechst 33258 staining, and TEM analysis. Furthermore, RNA-sequencing and KEGG functional enrichment analysis revealed that the necroptosis-related pathway was activated upon EG treatment in PC3 cells. mRNA and protein expression of necroptosis markers were analyzed by qPCR and immunoblotting, which implied that EG-induced cell necroptosis via enhancing the expression of MLKL and HSP90AA1 activating PGAM pathway which is considered as a key mediator of mitochondrial fission and leading to ROS generation in PC3 and DU145 cells. Thus, our findings suggested that EG is a new small molecule agonist that induced necroptosis in prostate cancer cells via the mitochondrial fission HSP90/MLKL/PGAM pathway.