ZFP750 affects the cutaneous barrier through regulating lipid metabolism.

An essential function of the epidermis is to provide a physical barrier that prevents the loss of water. Essential mediators of this barrier function include ceramides, cholesterol, and very long chain fatty acids, and their alteration causes human pathologies, including psoriasis and atopic dermatitis. A frameshift mutation in the human ZNF750 gene, which encodes a zinc finger transcription factor, has been shown to cause a seborrhea-like dermatitis. Here, we show that genetic deletion of the mouse homolog ZFP750 results in loss of epidermal barrier function, which is associated with a substantial reduction of ceramides, nonpolar lipids. The alteration of epidermal lipid homeostasis is directly linked to the transcriptional activity of ZFP750. ZFP750 directly and/or indirectly regulates the expression of crucial enzymes primarily involved in the biosynthesis of ceramides. Overall, our study identifies the transcription factor ZFP750 as a master regulator epidermal homeostasis through lipid biosynthesis and thus contributing to our understanding of the pathogenesis of several human skin diseases.

Metabolic regulation by p53 prevents R-loop-associated genomic instability.

Gene-environment interactions can perturb the epigenome, triggering network alterations that participate in cancer pathogenesis. Integrating epigenomics, transcriptomics, and metabolic analyses with functional perturbation, we show that the tumor suppressor p53 preserves genomic integrity by empowering adequate levels of the universal methyl donor S-adenosylmethionine (SAM). In p53-deficient cells, perturbation of DNA methylation promotes derepression of heterochromatin, massive loss of histone H3-lysine 9 methylation, and consequent upregulation of satellite RNAs that triggers R-loop-associated replication stress and chromosomal aberrations. In p53-deficient cells, the inadequate SAM level underlies the inability to respond to perturbation because exogenous reintroduction of SAM represses satellite elements and restores the ability to cope with stress. Mechanistically, p53 transcriptionally controls genes involved in one-carbon metabolism, including Slc43a2, the methionine uptake transporter that is critical for SAM synthesis. Supported by clinical data, our findings shed light on the role of p53-mediated metabolism in preventing unscheduled R-loop-associated genomic instability.

P73 C-terminus is dispensable for multiciliogenesis.

The p53 family transcriptional factor p73 plays a pivotal role in development. Ablation of p73 results in severe neurodevelopmental defects, chronic infections, inflammation and infertility. In addition to this, Trp73-\- mice display severe alteration in the ciliated epithelial lining and the full-length N-terminal isoform TAp73 has been implicated in the control of multiciliogenesis transcriptional program. With our recently generated Trp73Δ13/Δ13 mouse model, we interrogate the physiological role of p73 C-terminal isoforms in vivo. Trp73Δ13/Δ13 mice lack exon 13 in Trp73 gene, producing an ectopic switch from the C-terminal isoforms p73α to p73ß. Trp73Δ13/Δ13 mice show a pattern of expression of TAp73 comparable to the wild-type littermates, indicating that the α to ß switch does not significantly alter the expression of the gene in this cell type. Moreover, Trp73Δ13/Δ13 do not display any significant alteration in the airway ciliated epithelium, suggesting that in this context p73ß can fully substitute the function of the longer isoform p73α. Similarly, Trp73Δ13/Δ13 ciliated epithelium of the brain ependyma also does appear defective. In this district however expression of TAp73 is not detectable, indicating that expression of the gene might be compensated by alternative mechanisms. Overall our work indicates that C-terminus p73 is dispensable for the multiciliogenesis program and suggests a possible tissue-specific effect of p73 alternative splicing.

The C terminus of p73 is essential for hippocampal development.

The p53 family member p73 has a complex gene structure, including alternative promoters and alternative splicing of the 3' UTR. This results in a complex range of isoforms whose biological relevance largely remains to be determined. By deleting exon 13 (which encodes a sterile α motif) from the Trp73 gene, we selectively engineered mice to replace the most abundantly expressed C-terminal isoform, p73α, with a shorter product of alternative splicing, p73ß. These mice (Trp73Δ13/Δ13 ) display severe neurodevelopmental defects with significant functional and morphological abnormalities. Replacement of p73α with p73ß results in the depletion of Cajal-Retzius (CR) cells in embryonic stages, thus depriving the developing hippocampus of the pool of neurons necessary for correct hippocampal architecture. Consequently, Trp73Δ13/Δ13 mice display severe hippocampal dysgenesis, reduced synaptic functionality and impaired learning and memory capabilities. Our data shed light on the relevance of p73 alternative splicing and show that the full-length C terminus of p73 is essential for hippocampal development.

ZNF750 represses breast cancer invasion via epigenetic control of prometastatic genes.

Breast cancer is the second leading cause of cancer-related deaths among women, largely due to the progression of a significant fraction of primary tumours to the metastatic stage. Here, we show that zinc-finger protein 750 (ZNF750) opposes the migration and invasion of breast cancer cells by repressing a prometastatic transcriptional programme, which includes genes involved in focal adhesion and extracellular matrix interactions, such as LAMB3 and CTNNAL1. Mechanistically, ZNF750 recruits the epigenetic modifiers KDM1A and HDAC1 to the promoter regions of LAMB3 and CTNNAL1, influencing histone marks and transactivating these genomic sites. Gene expression analysis in cancer patient datasets indicated that ZNF750 and its targets were negative prognostic factors in breast cancer. Together, our findings shed light on the molecular mechanism by which ZNF750 regulates cell migration and invasion, suggesting a role in breast cancer metastasis.

American Association of Kidney Patients survey of patient preferences for hemodialysis vascular access.

OBJECTIVES: To determine the vascular access modalities used for hemodialysis, the reasons for choosing them, and determinants of satisfaction with vascular access among patients with end-stage renal disease. METHODS: The American Association of Kidney Patients Center for Patient Research and Education used the American Association of Kidney Patients patient engagement database to identify eligible adult hemodialysis patients. Participants completed an online survey consisting of 34 demographic, medical history, and hemodialysis history questions to determine which vascular access modalities were preferred and the reasons for these preferences. RESULTS: Among 150 respondents (mean age 54 years, 53% females), hemodialysis was most frequently initiated with central venous catheter (64%) while the most common currently used vascular access was arteriovenous fistula (66%). Most (86%) patients previously received an arteriovenous fistula, among whom 77% currently used the arteriovenous fistula for vascular access. Older patients and males were more likely to initiate hemodialysis with an arteriovenous fistula. The factors most frequently reported as important in influencing the selection of vascular access modality included infection risk (87%), physician recommendation (84%), vascular access durability (78%), risk of complications involving surgery (76%), and impact on daily activities (73%); these factors were influenced by patient age, sex, and race. Satisfaction with current vascular access was 90% with arteriovenous fistula, 79% with arteriovenous graft, and 67% with central venous catheter. CONCLUSION: Most end-stage renal disease patients continue to initiate hemodialysis with central venous catheter despite being associated with the lowest satisfaction rates. While arteriovenous fistula was associated with the highest satisfaction rate, there are significant barriers to adoption that vary based on patient demographics and perception of procedure invasiveness.

p53 mutants cooperate with HIF-1 in transcriptional regulation of extracellular matrix components to promote tumor progression.

Mutations in the TP53 gene and microenvironmentally driven activation of hypoxia-inducible factor-1 (HIF-1) typically occur in later stages of tumorigenesis. An ongoing challenge is the identification of molecular determinants of advanced cancer pathogenesis to design alternative last-line therapeutic options. Here, we report that p53 mutants influence the tumor microenvironment by cooperating with HIF-1 to promote cancer progression. We demonstrate that in non-small cell lung cancer (NSCLC), p53 mutants exert a gain-of-function (GOF) effect on HIF-1, thus regulating a selective gene expression signature involved in protumorigenic functions. Hypoxia-mediated activation of HIF-1 leads to the formation of a p53 mutant/HIF-1 complex that physically binds the SWI/SNF chromatin remodeling complex, promoting expression of a selective subset of hypoxia-responsive genes. Depletion of p53 mutants impairs the HIF-mediated up-regulation of extracellular matrix (ECM) components, including type VIIa1 collagen and laminin-γ2, thus affecting tumorigenic potential of NSCLC cells in vitro and in mouse models in vivo. Analysis of surgically resected human NSCLC revealed that expression of this ECM gene signature was highly correlated with hypoxic tumors exclusively in patients carrying p53 mutations and was associated with poor prognosis. Our data reveal a GOF effect of p53 mutants in hypoxic tumors and suggest synergistic activities of p53 and HIF-1. These findings have important implications for cancer progression and might provide innovative last-line treatment options for advanced NSCLC.

ZNF281 inhibits neuronal differentiation and is a prognostic marker for neuroblastoma.

Derangement of cellular differentiation because of mutation or inappropriate expression of specific genes is a common feature in tumors. Here, we show that the expression of ZNF281, a zinc finger factor involved in several cellular processes, decreases during terminal differentiation of murine cortical neurons and in retinoic acid-induced differentiation of neuroblastoma (NB) cells. The ectopic expression of ZNF281 inhibits the neuronal differentiation of murine cortical neurons and NB cells, whereas its silencing causes the opposite effect. Furthermore, TAp73 inhibits the expression of ZNF281 through miR34a. Conversely, MYCN promotes the expression of ZNF281 at least in part by inhibiting miR34a. These findings imply a functional network that includes p73, MYCN, and ZNF281 in NB cells, where ZNF281 acts by negatively affecting neuronal differentiation. Array analysis of NB cells silenced for ZNF281 expression identified GDNF and NRP2 as two transcriptional targets inhibited by ZNF281. Binding of ZNF281 to the promoters of these genes suggests a direct mechanism of repression. Bioinformatic analysis of NB datasets indicates that ZNF281 expression is higher in aggressive, undifferentiated stage 4 than in localized stage 1 tumors supporting a central role of ZNF281 in affecting the differentiation of NB. Furthermore, patients with NB with high expression of ZNF281 have a poor clinical outcome compared with low-expressors. These observations suggest that ZNF281 is a controller of neuronal differentiation that should be evaluated as a prognostic marker in NB.

TAp73 contributes to the oxidative stress response by regulating protein synthesis.

TAp73 is a transcription factor that plays key roles in brain development, aging, and cancer. At the cellular level, TAp73 is a critical homeostasis-maintaining factor, particularly following oxidative stress. Although major studies focused on TAp73 transcriptional activities have indicated a contribution of TAp73 to cellular metabolism, the mechanisms underlying its role in redox homeostasis have not been completely elucidated. Here we show that TAp73 contributes to the oxidative stress response by participating in the control of protein synthesis. Regulation of mRNA translation occupies a central position in cellular homeostasis during the stress response, often by reducing global rates of protein synthesis and promoting translation of specific mRNAs. TAp73 depletion results in aberrant ribosomal RNA (rRNA) processing and impaired protein synthesis. In particular, polysomal profiles show that TAp73 promotes the integration of mRNAs that encode rRNA-processing factors in polysomes, supporting their translation. Concurrently, TAp73 depletion causes increased sensitivity to oxidative stress that correlates with reduced ATP levels, hyperactivation of AMPK, and translational defects. TAp73 is important for maintaining active translation of mitochondrial transcripts in response to oxidative stress, thus promoting mitochondrial activity. Our results indicate that TAp73 contributes to redox homeostasis by affecting the translational machinery, facilitating the translation of specific mitochondrial transcripts. This study identifies a mechanism by which TAp73 contributes to the oxidative stress response and describes a completely unexpected role for TAp73 in regulating protein synthesis.

p73 Regulates Primary Cortical Neuron Metabolism: a Global Metabolic Profile.

The transcription factor p73 has been demonstrated to play a significant role in survival and differentiation of neuronal stem cells. In this report, by employing comprehensive metabolic profile and mitochondrial bioenergetics analysis, we have explored the metabolic alterations in cortical neurons isolated from p73 N-terminal isoform specific knockout animals. We found that loss of the TAp73 or ΔNp73 triggers selective biochemical changes. In particular, p73 isoforms regulate sphingolipid and phospholipid biochemical pathway signaling. Indeed, sphinganine and sphingosine levels were reduced in p73-depleted cortical neurons, and decreased levels of several membrane phospholipids were also observed. Moreover, in line with the complexity associated with p73 functions, loss of the TAp73 seems to increase glycolysis, whereas on the contrary, loss of ΔNp73 isoform reduces glucose metabolism, indicating an isoform-specific differential effect on glycolysis. These changes in glycolytic flux were not reflected by parallel alterations of mitochondrial respiration, as only a slight increase of mitochondrial maximal respiration was observed in p73-depleted cortical neurons. Overall, our findings reinforce the key role of p73 in regulating cellular metabolism and point out that p73 exerts its functions in neuronal biology at least partially through the regulation of metabolic pathways.

Integrin-ß4 is a novel transcriptional target of TAp73.

As a member of p53 family, p73 has attracted intense investigations due to its structural and functional similarities to p53. Among more than ten p73 variants, the transactivation (TA) domain-containing isoform TAp73 is the one that imitates the p53's behavior most. TAp73 induces apoptosis and cell cycle arrest, which endows it the capacity of tumour suppression. Also, it can exert diverse biological influences on cells through activating a complex and context dependent transcriptional programme. The transcriptional activities further broaden its roles in more intricate biological processes. In this article, we report that p73 is a positive regulator of a cell adhesion related gene named integrin ß4 (ITGB4). This finding may have implications for the dissection of the biological mechanisms underlining p73 functions.

TAp73 upregulates IL-1ß in cancer cells: Potential biomarker in lung and breast cancer?

p73 is a transcription factor belonging to the p53 tumour suppressor family. p73-/- mice exhibit a range of phenotypes including neurological, reproductive and inflammatory defects. Although the role of p73 in the control of genomic stability explains part of these phenotypes, a clear mechanism of how p73 participates in the inflammatory response is still elusive. Interleukin-1ß (IL-1ß) has a crucial role in mediating the inflammatory response. Because of its high potency to induce inflammation, the activation and secretion of IL-1ß is tightly regulated by large protein complexes, named inflammasomes. Inflammasomes regulate activation of proinflammatory caspase-1, which in turn proteolytically processes its substrates, including pro-IL-1ß. Caspase-1 gene transcription is strongly activated by p53 protein family members including p73. Here, we have addressed whether p73 might be directly involved in IL-1ß regulation and therefore in the control of the inflammatory response. Our results show that TAp73ß upregulates pro-IL-1ß mRNA and processed IL-1ß protein. In addition, analysis of breast and lung cancer patient cohorts demonstrated that interaction between p73 and IL-1ß predicts a negative survival outcome in these human cancers.

Polypharmacology of Approved Anticancer Drugs.

The major drug discovery efforts in oncology have been concentrated on the development of selective molecules that are supposed to act specifically on one anticancer mechanism by modulating a single or several closely related drug targets. However, a bird's eye view on data from multiple available bioassays implies that most approved anticancer agents do, in fact, target many more proteins with different functions. Here we will review and systematize currently available information on the targets of several anticancer drugs along with revision of their potential mechanisms of action. Polypharmacology of the current antineoplastic agents suggests that drug clinical efficacy in oncology can be achieved only via modulation of multiple cellular mechanisms.

How Does p73 Cause Neuronal Defects?

The p53-family member, p73, plays a key role in the development of the central nervous system (CNS), in senescence, and in tumor formation. The role of p73 in neuronal differentiation is complex and involves several downstream pathways. Indeed, in the last few years, we have learnt that TAp73 directly or indirectly regulates several genes involved in neural biology. In particular, TAp73 is involved in the maintenance of neural stem/progenitor cell self-renewal and differentiation throughout the regulation of SOX-2, Hey-2, TRIM32 and Notch. In addition, TAp73 is also implicated in the regulation of the differentiation and function of postmitotic neurons by regulating the expression of p75NTR and GLS2 (glutamine metabolism). Further still, the regulation of miR-34a by TAp73 indicates that microRNAs can also participate in this multifunctional role of p73 in adult brain physiology. However, contradictory results still exist in the relationship between p73 and brain disorders, and this remains an important area for further investigation.

Exploration of individuality in drug metabolism by high-throughput metabolomics: The fast line for personalized medicine.

In many cases, individuality in metabolism of a drug is a reliable predictor of the drug efficacy/safety. Modern high-throughput metabolomics is an ideal instrument to track drug metabolism in an individual after treatment. Productivity and low cost of the metabolomics are sufficient to analyse a large cohort of patients to explore individual variations in drug metabolism and to discover drug metabolic biomarkers indicative of drug efficacy/safety. The only potential disadvantage of metabolomics becoming a routine clinical procedure is a need to treat the patient once before making a prognosis. However, in many clinical applications this would not be a limitation. Here, we explore current opportunities and challenges for translating high-throughput metabolomics into the platform for personalized medicine.

Polypharmacology of small molecules targeting the ubiquitin-proteasome and ubiquitin-like systems.

Targeting the ubiquitin-proteasome system (UPS) and ubiquitin-like signalling systems (UBL) has been considered a promising therapeutic strategy to treat cancer, neurodegenerative and immunological disorders. There have been multiple efforts recently to identify novel compounds that efficiently modulate the activities of different disease-specific components of the UPS-UBL. However, it is evident that polypharmacology (the ability to affect multiple independent protein targets) is a basic property of small molecules and even highly potent molecules would have a number of "off target" effects. Here we have explored publicly available high-throughput screening data covering a wide spectrum of currently accepted drug targets in order to understand polypharmacology of small molecules targeting different components of the UPS-UBL. We have demonstrated that molecules targeting a given UPS-UBL protein also have high odds to target a given off target spectrum. Moreover, the off target spectrum differs significantly between different components of UPS-UBL. This information can be utilized further in drug discovery efforts, to improve drug efficiency and to reduce the risk of potential side effects of the prospective drugs designed to target specific UPS-UBL components.

TAp73 transcriptionally represses BNIP3 expression.

TAp73 is a tumor suppressor transcriptional factor, belonging to p53 family. Alteration of TAp73 in tumors might lead to reduced DNA damage response, cell cycle arrest and apoptosis. Carcinogen-induced TAp73(-/-) tumors display also increased angiogenesis, associated to hyperactivition of hypoxia inducible factor signaling. Here, we show that TAp73 suppresses BNIP3 expression, directly binding its gene promoter. BNIP3 is a hypoxia responsive protein, involved in a variety of cellular processes, such as autophagy, mitophagy, apoptosis and necrotic-like cell death. Therefore, through different cellular process altered expression of BNIP3 may differently contribute to cancer development and progression. We found a significant upregulation of BNIP3 in human lung cancer datasets, and we identified a direct association between BNIP3 expression and survival rate of lung cancer patients. Our data therefore provide a novel transcriptional target of TAp73, associated to its antagonistic role on HIF signaling in cancer, which might play a role in tumor suppression.