Identification and characterization of a novel potential transcription factor involved in osteogenic differentiation of mesenchymal stem cells.

Osteogenesis is a complex and still poorly understood biological process regulated by intrinsic cellular signals and extrinsic micro-environmental stimuli from the surrounding stem cell-niche. Some regulators of osteogenesis, including growth factors and transcriptional factors, have been already identified, although further studies to better elucidate the molecular basis of this biological process are required in order to develop new and more effective therapeutic strategies for the treatment of osteogenic diseases, such as osteoporosis, bone fractures and osteosarcoma. Osteoblasts arise from mesenchymal stem cells (MSCs), which are adult multipotent stem cells that can be successfully isolated from several adult and neonatal tissues, are able to generate, following appropriate stimuli, several differentiated mesoderm-derived cell lineages, including adipocytes, osteoblasts, chondrocytes and myoblasts and, therefore, represent a promising cell source for regenerative medicine. In order to identify genes involved in the commitment of MSCs to osteoblasts, we performed a screening with an RNA interference-based approach and silenced a large number of genes during osteoblast differentiation of a murine MSC-derived cell line (W20-17). With this procedure we identified several candidate genes potentially involved in osteogenesis; in fact, their silencing caused a reduction of mineralized deposits, as assessed by Alizarin Red staining. We then analyzed the Gene Ontology classification of candidate genes and we found a significant fraction (30%) of genes with unknown function at the time of the screening. Hence, we focused our attention on one of these genes that we named Osteoblasts Inducer (ObI-1), predicted to be a transcription factor. Indeed, Ensembl analysis showed that ObI-1 encodes for a protein containing several zinc-finger domains and a Kruppel-associated box (KRAB) domain, usually involved in transcriptional repression. We were able to observe a significant impairment in osteoblast differentiation, resulting in reduction of both alkaline phosphatase expression and mineralization, as a result of ObI-1 silencing. In addition, we evaluated ObI-1 expression in our cell system as well as in several mouse tissues and organs. Interestingly, ObI1 expression increases during osteogenic differentiation of both W20-17 cell line and primary murine MSCs from bone marrow. We demonstrated also the nuclear localization of ObI-1 through immunofluorescence analysis, corroborating the hypothesis that this gene may encode for a transcription factor. Finally, we analyzed the effect of ObI-1 silencing on the expression of osteogenic markers during the differentiation process

Angiotensin receptor I stimulates osteoprogenitor proliferation through TGFβ-mediated signaling:AT1R SIGNALING IN OSTEOBLAST DIFFERENTIATION

Clinical studies of large human populations and pharmacological interventions in rodent models have recently suggested that anti-hypertensive drugs that target angiotensin II (Ang II) activity may also reduce loss of bone mineral density. Here, we identified in a genetic screening the Ang II type I receptor (AT1R) as a potential determinant of osteogenic differentiation and, implicitly, bone formation. Silencing of AT1R expression by RNA interference severely impaired the maturation of a multipotent mesenchymal cell line (W20-17) along the osteoblastic lineage. The same effect was also observed after the addition of the AT1R antagonist losartan but not the AT2R inhibitor PD123,319. Additional cell culture assays traced the time of greatest losartan action to the early stages of W20-17 differentiation, namely during cell proliferation. Indeed, addition of Ang II increased proliferation of differentiating W20-17 and primary mesenchymal stem cells and this stimulation was reversed by losartan treatment. Cells treated with losartan also displayed an appreciable decrease of activated (phosphorylated)-Smad2/3 proteins. Moreover, Ang II treatment elevated endogenous transforming growth factor β (TGFβ) expression considerably and in an AT1R-dependent manner. Finally, exogenous TGFβ was able to restore high proliferative activity to W20-17 cells that were treated with both Ang II and losartan. Collectively, these results suggest a novel mechanism of Ang II action in bone metabolism that is mediated by TGFβ and targets proliferation of osteoblast progenitors

Angiotensin receptor I stimulates osteoprogenitor proliferation through TGFβ-mediated signaling

Clinical studies of large human populations and pharmacological interventions in rodent models have recently suggested that anti-hypertensive drugs that target angiotensin II (Ang II) activity may also improve loss of bone mineral density. Here we identified in a genetic screen the Ang II type I receptor (AT1R) as a potential determinant of osteogenic differentiation and, implicitly, bone formation. Silencing of AT1R expression by RNA interference severely impaired the maturation of a multipotent mesenchymal cell line (W20-17) along the osteoblastic lineage. The same effect was also observed after the addition of the AT1R antagonist losartan but not the AT2R inhibitor PD123,319. Additional cell culture assays traced the time of greatest losartan action to the early stages of W20-17 differentiation, namely during cell proliferation. Indeed, addition of Ang II increased proliferation of differentiating W20-17 and primary mesenchymal stem cells and this stimulation was reversed by losartan treatment. Cells treated with losartan also displayed an appreciable decrease of activated (phosphorylated)-Smad2/3 proteins. Moreover, Ang II treatment elevated endogenous transforming growth factor β (TGFβ) expression considerably and in an AT1R-dependent manner. Finally, exogenous TGFβ was able to restore high proliferative activity to W20-17 cells that were treated with both Ang II and losartan. Collectively, these results suggest a novel mechanism of Ang II action in bone metabolism that is mediated by TGFβ and targets proliferation of osteoblast progenitors

S18-phosphorylation of USP7 regulates interaction with TCEAL4 that defines specific complexes and potentially distinct functions

AbstractUSP7 is a nuclear deubiquitylase (DUB) with multiple cancer-associated substrates for which selective inhibitors are available, yet it remains unclear how the pleiotropic effects of USP7 are regulated. We report that S18-phosphorylation does not influence USP7 catalytic activity but instead confers selectivity for protein interactions. In particular, non-S18-phosphorylatable USP7 preferentially interacts with USP11 and TRIM27, together with TCEAL1 and TCEAL4 whose functions are unknown. Intriguingly, USP7 can interact with two cellular forms of TCEAL4, but USP11 only interacts with a lower abundance K142 mono-ubiquitylated form (TCEAL4-Ub), which can scaffold a complex containing both DUBs. Whilst USP11 and TCEAL4 are both USP7 substrates, TCEAL4-Ub levels are specifically maintained by USP11 with their levels positively correlated in cancer cell lines. Together these data illustrate how USP7 phosphorylation and TCEAL4 ubiquitylation combine to define distinct USP7 complexes. As TCEAL4 itself interacts with proteins involved in ubiquitylation and various forms of DNA regulation, these complexes may direct cellular activity of USP7.</jats:p

Retinal vascular alterations in reticular pseudodrusen with and without outer retinal atrophy assessed by optical coherence tomography angiography

PURPOSE: To investigate the intraretinal structural and vascular alterations in patients featuring reticular pseudodrusen (RPD), RPD with outer retinal atrophy (ORA), and drusen. DESIGN: Observational cross-sectional study. METHODS: Clinical practice study including 68 eyes of 57 patients (22 eyes of 17 patients with RPD; 24 eyes of 21 patients with RPD+ORA; 22 eyes of 19 patients with drusen). Each patient underwent spectral-domain optical coherence tomography (OCT) and OCT angiography (OCT-A). Measurement of retinal layers' thickness was obtained by the automated segmentation protocol of the Spectralis OCT (Heidelberg Eye Explorer V.1.9.10.0). The superficial capillary plexus (SCP) and the deep capillary plexus (DCP) vessel density, as well as the size of the foveal avascular zone were calculated on 3 73\u2009OCT-A. Main outcome was to compare vessel density at the SCP and DCP among the groups and controls. RESULTS: At the SCP, the vessel density was lower in RPD and RPD+ORA patients with respect to controls (P=0.02\u2009and P=0.003, respectively). At the DCP, meaningful disparity was found between the study groups and the healthy subjects in the vessel density (P<0.001, P=0.04 and P=0.001 for RPD, RDP+ORA and drusen, respectively). The ganglion cell layer (GCL) was thinner in all patients affected either by RPD, RPD+ORA\u2009or drusen compared with healthy subjects (P=0.02, P=0.03 and P=0.004,\u2009respectively). CONCLUSION: Significant retinal vascular loss is a common feature of patients with non-exudative age-related macular degeneration, more pronounced in those featuring RPD and RPD+ORA. It is associated with retinal thinning, localised particularly at the GCL, compared with controls

Multimodal Imaging Assessment of Vascular and Neurodegenerative Retinal Alterations in Type 1 Diabetic Patients without Fundoscopic Signs of Diabetic Retinopathy

The aim of this cross-sectional case-control study is to investigate the possible presence of vascular/neurodegenerative alterations in the retina of type 1 diabetes mellitus (T1DM) patients without diabetic retinopathy (DR). Thirty-four eyes of 34 consecutive T1DM without DR (mean age 21 &plusmn; 2 years) were included. Another cohort of 27 eyes (27 healthy control subjects matched with age and sex) was also recruited. All patients underwent multimodal imaging evaluation using structural optical coherence tomography (OCT), OCT-angiography (OCT-A), dynamic vessel analyzer (DVA) and microperimetry. No significant differences were disclosed comparing diabetics and controls for visual acuity, central macular thickness, and subfoveal choroidal thickness. On retinal nerve fiber layer and ganglion cell complex thickness, no significant differences were disclosed comparing each 3-mm-diameter macular and peripapillary subfield between two groups. Using OCT-A, deep capillary plexus perfusion density (PD) of diabetics was significantly lower compared to control group, whereas PD of other retinal/choriocapillaris plexuses and foveal avascular zone area did not show any significant difference. Using DVA, diabetic eyes revealed a significantly decreased vessel response to flicker light in comparison to controls. No differences were disclosed using microperimetry analysis. Taken together, these results suggest that vascular alterations could be the first detectable retinal change in the development of DR

The retinal neurovascular coupling is impaired in men with vasculogenic erectile dysfunction

Abstract The aim of this study was to study the retinal vessels in patients affected by vasculogenic erectile dysfunction (ED), using dynamic vessel analyzer (DVA). Patients with vasculogenic ED and control subjects were prospectively enrolled to undergo a complete urological and ophthalmologic evaluation, including DVA and structural optical coherence tomography (OCT). The main outcome measures were: (1) arterial dilation; (2) arterial constriction; (3) reaction amplitude (the difference between arterial dilation and constriction); and, (4) venous dilation. Thirty-five patients with ED and 30 male controls were included in the analysis. Mean ± SD age was 52.0 ± 10.8 years in the ED group and 48.1 ± 16.3 years in the control group (p = 0.317). In the dynamic analysis, the arterial dilation was lower in the ED group (1.88 ± 1.50%), as compared with the control group (3.70 ± 1.56%, p < 0.0001). Neither arterial constriction nor venous dilation differed between groups. The reaction amplitude was decreased in ED patients (2.40 ± 2.02%, p = 0.023), compared to controls (4.25 ± 2.20%). In the Pearson correlation analysis, the ED severity, was directly correlated with both reaction amplitude (R = .701, p = 0.004) and arterial dilation (R = .529, p = 0.042). In conclusion, subjects with vasculogenic ED are featured by a significant dysfunction of the retinal neurovascular coupling, which is inversely correlated with ED severity

Atypical case of perifoveal exudative vascular anomalous complex associated with pachychoroid pigment epitheliopathy

Purpose: To report an unusual association of a perifoveal exudative vascular anomalous complex (PEVAC) and a bilateral pachychoroid pigment epitheliopathy (PPE), which responded positively to anti-vascular endothelial growth factor (VEGF) intravitreal injections (IVI). Observations: A 44 year-old man with no significant medical or ocular history, complained of unilateral blurred vision in his right eye (RE) over several months. On examination, best corrected visual acuity (BCVA) was 75 letters in the RE and 85 in the left eye (LE). Fundus examination in the RE showed a large perifoveal aneurysmal lesion with a macular thickening, small hemorrhages and linear hard exudates accumulation, associated with multifocal retinal pigment epithelium (RPE) changes in the posterior pole of both eyes. Optical coherence tomography of the RE showed the PEVAC as a large round retinal capillary aneurysm with surrounding intraretinal fluid, associated with serous and drusenoid RPE elevations in both eyes, consistent with PPE. Subfoveal choroidal thickness was more than 500 μm in both eyes, with several dilated choroidal veins. Fluorescein angiography showed, in the RE, the hyperfluorescent aneurysmal lesion with late leakage, associated with scattered hyperfluorescent areas in the posterior pole of both eyes. Indocyanine green angiography showed, in the RE, the same hyperfluorescent lesion but without leakage, associated with areas of choroidal hyperpermeability in both eyes. After 2 anti-VEGF IVI in the RE, good functional and anatomical improvement was observed. After 10 months of follow-up, there was no evidence of new exudation. BCVA remained stable and RPE abnormalities remained unchanged. Conclusion and importance: We describe an atypical case of PEVAC associated with PPE, which responded positively to anti-VEGF therapy. To our knowledge, this is the first report of a patient presenting PEVAC and diseases of the pachychoroid spectrum. Further studies, assessing the choroid in PEVAC, are required to investigate the hypothetical relationship between these 2 entities and the efficiency of anti-VEGF therapy