Search

The glycogen synthase kinase 3β (GSK-3β) is a ubiquitous enzyme that is a validated target for the development of potential therapeutics useful in several diseases including retinal degeneration. Aiming at developing an innovative class of allosteric inhibitors of GSK-3β potentially useful for retinal degeneration, we explored the class of squaramides. The developed compounds (6 a-l) were obtained through a nontoxic one-pot synthetic protocol, which employs low-cost goods and avoids any purification step. Ethanol was used as the reaction solvent, simultaneously allowing the pure reaction products' recovery (by precipitation). Out of this set of squaramides, 6 j stood out, from computational and enzymatic converging data, as an ATP non-competitive inhibitor of GSK-3β of micromolar potency. When engaged in cellular studies using retinal pigment epithelial cells (ARPE-19) transfected with a luciferase reporter gene under the control of T-cell factor/lymphoid enhancer factor (TCF/LEF) binding sites, 6 j was able to dose-dependently induce β-catenin nuclear accumulation, as shown by the increased luciferase activity at a concentration of 2.5 μM.

During skeletal myogenesis, the zinc-finger transcription factors SNAI1 and SNAI2, are expressed in proliferating myoblasts and regulate the transition to terminally differentiated myotubes while repressing pro-differentiation genes. Here, we demonstrate that SNAI1 is upregulated in vivo during the early phase of muscle regeneration induced by bupivacaine injury. Using shRNA-mediated gene silencing in C2C12 myoblasts and whole-transcriptome microarray analysis, we identified a collection of genes belonging to the endoplasmic reticulum (ER) stress pathway whose expression, induced by myogenic differentiation, was upregulated in absence of SNAI1. Among these, key ER stress genes, such as Atf3, Ddit3/Chop, Hspa5/Bip, and Fgf21, a myokine involved in muscle differentiation, were strongly upregulated. Furthermore, by promoter mutant analysis and Chromatin immune precipitation assay, we demonstrated that SNAI1 represses Fgf21 and Atf3 in proliferating myoblasts by directly binding to multiple E boxes in their respective promoter regions. Together, these data describe a new regulatory mechanism of myogenic differentiation involving the direct repressive action of SNAI1 on ER stress and Fgf21 expression, ultimately contributing to maintaining the proliferative and undifferentiated state of myoblasts.

In patients with age-related macular degeneration (AMD), choroidal neovascularization is the major cause of severe visual loss. In these patients, the persistence of neovascular growth despite vascular endothelial growth factor-A blockage needs the discovery of new endothelial cell targets. The glycoprotein CD93, highly expressed in activated endothelial cells, has been recently involved in the regulation of the angiogenic process both as transmembrane and soluble protein. Choroidal neovascular membranes from patients affected by AMD were examined by immunofluorescence using anti-CD93 and anti-von Willebrand factor antibodies. Blood vessels within intraocular and extraocular neoplasias were used as controls for CD93 expression. All choroidal neovascular membranes displayed strong CD93 staining in the von Willebrand factor-positive endothelial cells, consistently with the analyses showing a high colocalization coefficient in the blood vessels. Intraocular and extraocular tumor vessels showed similar results, whereas the normal choroid displayed blood vessels with only faint CD93 staining. Additionally, the concentration of soluble CD93 was determined in the aqueous humor of patients affected by naive neovascular AMD by enzyme-linked immunosorbent assays. Age-matched cataract patients served as controls. Soluble CD93 was significantly increased in the aqueous humor of naive neovascular AMD patients and tended to decrease after treatment with an antiangiogenic drug. In conclusion, both transmembrane and soluble CD93 are overexpressed in patients with neovascular AMD, indicating that CD93 may represent a potential new antiangiogenic target in the treatment of choroidal neovascularization. J. Cell. Physiol. 232: 1767-1773, 2017. © 2016 Wiley Periodicals, Inc.

Alkaptonuria (AKU) is a rare genetic disease that affects the entire joint. Current standard of AKU treatment is palliative and little is known about its physiopathology. Neovascularization is involved in the pathogenesis of systemic inflammatory rheumatic diseases, a family of related disorders that includes AKU. Here, we investigated the presence of neoangiogenesis in AKU synovium and healthy controls. Synovium from AKU patients, who had undergone total joint replacement or arthroscopy, or from healthy patients without any history of rheumatic diseases, who underwent surgical operation following sport trauma was subjected to hematoxylin and eosin staining. Histologic grades were assigned for clinical disease activity and synovitis based on cellular content of the synovium. By immunofluorescence microscopy, using different endothelial cell markers, we observed large vascularization in AKU but not in healthy synovium. Moreover, Western blotting and quantification analyses confirmed strong expression of endothelial cell markers in AKU synovial tissues. Importantly, AKU synovium vascular endothelium expressed high levels of β-dystroglycan, a protein previously involved in the regulation of angiogenesis in osteoarthritic synovium. This is the first report providing experimental evidences that new blood vessels are formed in AKU synovial tissues, opening new perspectives for AKU therapy.