Cezanne regulates E2F1-dependent HIF2α expression

Mechanisms regulating protein degradation ensure the correct and timely expression of transcription factors such as hypoxia inducible factor (HIF). Under normal O2 tension, HIFα subunits are targeted for proteasomal degradation, mainly through vHL-dependent ubiquitylation. Deubiquitylases are responsible for reversing this process. Although the mechanism and regulation of HIFα by ubiquitin-dependent proteasomal degradation has been the object of many studies, little is known about the role of deubiquitylases. Here, we show that expression of HIF2α (encoded by EPAS1) is regulated by the deubiquitylase Cezanne (also known as OTUD7B) in an E2F1-dependent manner. Knockdown of Cezanne downregulates HIF2α mRNA, protein and activity independently of hypoxia and proteasomal degradation. Mechanistically, expression of the HIF2α gene is controlled directly by E2F1, and Cezanne regulates the stability of E2F1. Exogenous E2F1 can rescue HIF2α transcript and protein expression when Cezanne is depleted. Taken together, these data reveal a novel mechanism for the regulation of the expression of HIF2α, demonstrating that the HIF2α promoter is regulated by E2F1 directly and that Cezanne regulates HIF2α expression through control of E2F1 levels. Our results thus suggest that HIF2α is controlled transcriptionally in a cell-cycle-dependent manner and in response to oncogenic signalling

Chronic p53-independent p21 expression causes genomic instability by deregulating replication licensing

The cyclin-dependent kinase inhibitor p21WAF1/CIP1 (p21) is a cell-cycle checkpoint effector and inducer of senescence, regulated by p53. Yet, evidence suggests that p21 could also be oncogenic, through a mechanism that has so far remained obscure. We report that a subset of atypical cancerous cells strongly expressing p21 showed proliferation features. This occurred predominantly in p53-mutant human cancers, suggesting p53-independent upregulation of p21 selectively in more aggressive tumour cells. Multifaceted phenotypic and genomic analyses of p21-inducible, p53-null, cancerous and near-normal cellular models showed that after an initial senescence-like phase, a subpopulation of p21-expressing proliferating cells emerged, featuring increased genomic instability, aggressiveness and chemoresistance. Mechanistically, sustained p21 accumulation inhibited mainly the CRL4–CDT2 ubiquitin ligase, leading to deregulated origin licensing and replication stress. Collectively, our data reveal the tumour-promoting ability of p21 through deregulation of DNA replication licensing machinery—an unorthodox role to be considered in cancer treatment, since p21 responds to various stimuli including some chemotherapy drugs

From genetics to epigenetics: new perpectives in Tourette Syndrome research

Gilles de la Tourette Syndrome (TS) is a neurodevelopmental disorder marked by the appearance of multiple involuntary motor and vocal tics. TS presents high comorbidity rates with other disorders such as attention deficit hyperactivity disorder (ADHD) and obsessive compulsive disorder (OCD). TS is highly heritable and has a complex polygenic background. However, environmental factors also play a role in the manifestation of symptoms. Different epigenetic mechanisms may represent the link between these two causalities. Epigenetic regulation has been shown to have an impact in the development of many neuropsychiatric disorders, however very little is known about its effects on Tourette Syndrome.This review provides a summary of the recent findings in the genetic background of TS, followed by an overview on different epigenetic mechanisms, such as DNA methylation, histone modifications and non-coding RNAs in the regulation of gene expression. Epigenetic studies in other neurological and psychiatric disorders are discussed along with the TS-related epigenetic findings available in the literature to date. Moreover, we are proposing that some general epigenetic mechanisms seen in other neuropsychiatric disorders may also play a role in the pathogenesis of TS

Satpura: A Novel Framework for Density Estimation, Hotspot Discovery, Change Analysis, and Change-based Alerts

Due to the technological advancement in remote sensors and sensor networks, different types of spatio-temporal data are increasingly available. Spatio-temporal data analysis has applications in many fields, including criminology, epidemiology, and traffic analysis. The main focus of this research is to develop a generic analysis framework called Satpura, which provides density estimation, hotspot discovery, and change analysis capabilities for spatial data. The framework supports naïve, and kernel density estimation approaches for raw and relative densities. To identify density hotspots, we designed a novel hotspot discovery technique that generates rectangular hotspots for a given density threshold. We also developed a post-processing technique to remove redundant and highly overlapping hotspots. Since the density threshold plays a significant role in hotspot generation, we developed an automatic density threshold selection technique. Additionally, we developed evaluation metrics to assess the quality of the hotspots. To address change analysis, we developed two techniques: density-based change analysis, which is used to find the regions where there is a high density change with time, and hotspot-density-based change analysis, which is used to identify the density changes that occur in hotspots over time. Based on the change analysis, density-change-based alerts and hotspot-density-change-based alerts are provided by Satpura. Satpura, which was developed in Python as a web-based application, was used to analyze an Austin crime dataset. It successfully identified crime hotspots, and it analyzed changes that occurred in criminal activity. Then, an alert system was implemented to warn the public of new crime hotspots. Satpura was also used to analyze an Austin traffic accident dataset.Computer Science, Department o

Intranasal Interleukin-12 Treatment Promotes Antimicrobial Clearance and Survival in Pulmonary Francisella tularensis subsp. novicida Infection

Francisella tularensis is a highly virulent facultative intracellular bacterium and is considered a potential biological warfare agent. Inhalation tularemia can lead to the development of bronchopneumonia, which is frequently fatal without medical intervention. Treatment strategies that directly target the respiratory mucosa may extend the efficacy of therapy, particularly for the medical management of acute aerosol exposure. To this end, we describe an intranasal (i.n.) strategy for the treatment of pulmonary Francisella infection in mice that uses a combinatorial approach with the conventional antibiotic gentamicin and interleukin 12 (IL-12). The i.n. administration of IL-12 alone promoted bacterial clearance and extended the time to death but did not prevent mortality against lethal pulmonary challenge with Francisella tularensis subsp. novicida. However, i.n. treatment with gentamicin and IL-12 therapeutically at 8 and 24 h after challenge markedly enhanced the rate of survival (70 to 100%) against pulmonary infection compared to the rates of survival for animals treated with antibiotic alone (17%) or IL-12 alone (0%). A delay in combinatorial therapy over a span of 4 days progressively decreased the efficacy of this treatment regimen. This combinatorial treatment was shown to be highly dependent upon the induction of endogenous gamma interferon and may also involve the activation of natural killer cells. Together, these findings suggest that IL-12 may be a potent adjunct for chemotherapy to enhance drug effectiveness against pulmonary Francisella infection

The CRL4Cdt2 Ubiquitin Ligase Mediates the Proteolysis of Cyclin-Dependent Kinase Inhibitor Xic1 through a Direct Association with PCNA ▿

During DNA polymerase switching, the Xenopus laevis Cip/Kip-type cyclin-dependent kinase inhibitor Xic1 associates with trimeric proliferating cell nuclear antigen (PCNA) and is recruited to chromatin, where it is ubiquitinated and degraded. In this study, we show that the predominant E3 for Xic1 in the egg is the Cul4-DDB1-XCdt2 (Xenopus Cdt2) (CRL4Cdt2) ubiquitin ligase. The addition of full-length XCdt2 to the Xenopus extract promotes Xic1 turnover, while the N-terminal domain of XCdt2 (residues 1 to 400) cannot promote Xic1 turnover, despite its ability to bind both Xic1 and DDB1. Further analysis demonstrated that XCdt2 binds directly to PCNA through its C-terminal domain (residues 401 to 710), indicating that this interaction is important for promoting Xic1 turnover. We also identify the cis-acting sequences required for Xic1 binding to Cdt2. Xic1 binds to Cdt2 through two domains (residues 161 to 170 and 179 to 190) directly flanking the Xic1 PCNA binding domain (PIP box) but does not require PIP box sequences (residues 171 to 178). Similarly, human p21 binds to human Cdt2 through residues 156 to 161, adjacent to the p21 PIP box. In addition, we identify five lysine residues (K180, K182, K183, K188, and K193) immediately downstream of the Xic1 PIP box and within the second Cdt2 binding domain as critical sites for Xic1 ubiquitination. Our studies suggest a model in which both the CRL4Cdt2 E3- and PIP box-containing substrates, like Xic1, are recruited to chromatin through independent direct associations with PCNA