Screening Antibacterial Photodynamic Effect of Monascus Red Yeast Rice (Hong-Qu) and Mycelium Extracts.

The fungus Monascus is a well-known source of secondary metabolites with interesting pharmaceutical and nutraceutical applications. In particular, Monascus pigments possess a wide range of biological activities (e.g. antimicrobial, antioxidant, anti-inflammatory or antitumoral). To broaden the scope of their possible application, this study focused on testing Monascus pigment extracts as potential photosensitizing agents efficient in antimicrobial photodynamic therapy (aPDT) against bacteria. For this purpose, eight different extracts of secondary metabolites from the liquid- and solid-state fermentation of Monascus purpureus DBM 4360 and Monascus sp. DBM 4361 were tested against Gram-positive and Gram-negative model bacteria, Bacillus subtilis and Escherichia coli and further screened for ESKAPE pathogens, Staphylococcus aureus and Pseudomonas aeruginosa. To the bacterial culture, increasing concentration of extracts was added and it was found that all extracts showed varying antimicrobial activity against Gram-positive bacteria in dark, which was further increased after irradiation. Gram-negative bacteria were tolerant to the extracts' exposure in the dark but sensitivity to almost all extracts that occurred after irradiation. The Monascus sp. DBM 4361 extracts seemed to be the best potential candidate for aPDT against Gram-positive bacteria, being efficient at low doses, i.e. the lowest total concentration of Monascus pigments exhibiting aPDT effect was 3.92 ± 1.36 mg/L for E. coli. Our results indicate that Monascus spp., forming monascuspiloin as the major yellow pigment and not-forming mycotoxin citrinin, is a promising source of antimicrobials and photoantimicrobials.

Antibiofilm Activity of Combretum micranthum G. Don Catechin-Sugar Phytocomplex on Pseudomonas aeruginosa.

Clinicians often have to face infections caused by microorganisms that are difficult to eradicate due to their resistance and/or tolerance to antimicrobials. Among these pathogens, Pseudomonas aeruginosa causes chronic infections due to its ability to form biofilms on medical devices, skin wounds, ulcers and the lungs of patients with Cystic Fibrosis. In this scenario, the plant world represents an important reservoir of natural compounds with antimicrobial and/or antibiofilm properties. In this study, an extract from the leaves of Combretum micranthum G. Don, named Cm4-p, which was previously investigated for its antimicrobial activities, was assayed for its capacity to inhibit biofilm formation and/or to eradicate formed biofilms. The model strain P. aeruginosa PAO1 and its isogenic biofilm hyperproducer derivative B13 were treated with Cm4-p. Preliminary IR, UV-vis, NMR, and mass spectrometry analyses showed that the extract was mainly composed of catechins bearing different sugar moieties. The phytocomplex (3 g/L) inhibited the biofilm formation of both the PAO1 and B13 strains in a significant manner. In light of the obtained results, Cm4-p deserves deeper investigations of its potential in the antimicrobial field.

Ruthenium(II)-Arene Curcuminoid Complexes as Photosensitizer Agents for Antineoplastic and Antimicrobial Photodynamic Therapy: In Vitro and In Vivo Insights.

Photodynamic therapy (PDT) is an anticancer/antibacterial strategy in which photosensitizers (PSs), light, and molecular oxygen generate reactive oxygen species and induce cell death. PDT presents greater selectivity towards tumor cells than conventional chemotherapy; however, PSs have limitations that have prompted the search for new molecules featuring more favorable chemical-physical characteristics. Curcumin and its derivatives have been used in PDT. However, low water solubility, rapid metabolism, interference with other drugs, and low stability limit curcumin use. Chemical modifications have been proposed to improve curcumin activity, and metal-based PSs, especially ruthenium(II) complexes, have attracted considerable attention. This study aimed to characterize six Ru(II)-arene curcuminoids for anticancer and/or antibacterial PDT. The hydrophilicity, photodegradation rates, and singlet oxygen generation of the compounds were evaluated. The photodynamic effects on human colorectal cancer cell lines were also assessed, along with the ability of the compounds to induce ROS production, apoptotic, necrotic, and/or autophagic cell death. Overall, our encouraging results indicate that the Ru(II)-arene curcuminoid derivatives are worthy of further investigation and could represent an interesting option for cancer PDT. Additionally, the lack of significant in vivo toxicity on the larvae of Galleria mellonella is an important finding. Finally, the photoantimicrobial activity of HCurc I against Gram-positive bacteria is indeed promising.

Photo-Inactivation of Staphylococcus aureus by Diaryl-Porphyrins.

Photodynamic Antimicrobial Chemotherapy (PACT) has received great attention in recent years since it is an effective and promising modality for the treatment of human oral and skin infections with the advantage of bypassing pathogens' resistance to antimicrobials. Moreover, PACT applications demonstrated a certain activity in the inhibition and eradication of biofilms, overcoming the well-known tolerance of sessile communities to antimicrobial agents. In this study, 13 diaryl-porphyrins (mono-, di-cationic, and non-ionic) P1-P13 were investigated for their potential as photosensitizer anti-Staphylococcus aureus. The efficacy of the diaryl-porphyrins was evaluated through photo-inactivation tests. Crystal-violet staining combined with viable count techniques were aimed at assaying their anti-biofilm activity. Among the tested compounds, the neutral photosensitizer P4 was better than the cationic ones, irrespective of their corresponding binding rates. In particular, P4 was active in inhibiting the biofilm formation and in impairing the viability of the adherent and planktonic populations of a 24 h old biofilm. The inhibitory activity was also efficient against a methicillin resistant S. aureus strain. In conclusion, the diaryl-porphyrin family represents a reservoir of promising compounds for photodynamic applications against the pathogen S. aureus and in preventing the formation of biofilms that cause many infections to become chronic.

Searching for antimicrobial photosensitizers among a panel of BODIPYs.

In recent years, antimicrobial Photodynamic Therapy (aPDT) gained increasing attention for its potential to inhibit the growth and spread of microorganisms, both as free-living cells and/or embedded in biofilm communities. In this scenario, compounds belonging to the family of boron-dipyrromethenes (BODIPYs) represent a very promising class of photosensitizers for applications in antimicrobial field. In this study, twelve non-ionic and three cationic BODIPYs were assayed for the inactivation of Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans. As expected, S. aureus showed to be very sensitive to BODIPYs and mild conditions were sufficient to reach good rates of photoinactivation with both neutral and monocationic ones. Surprisingly, one neutral compound (named B9 in this study) resulted the best BODIPY to photoinactivate P. aeruginosa PAO1. The photoinactivation of C. albicans was reached with both neutral and mono-cationic BODIPYs. Furthermore, biofilms of the three model microorganisms were challenged with BODIPYs in light-based antimicrobial technique. S. aureus biofilms were successfully inhibited with milder conditions than those applied to P. aeruginosa and C. albicans. Notably, it was possible to eradicate 24-h-old biofilms of both S. aureus and P. aeruginosa. In conclusion, this study supports the potential of neutral BODIPYs as pan-antimicrobial PSs.

Bacterial pigments: A colorful palette reservoir for biotechnological applications.

Synthetic derivatives are currently used instead of pigments in many applicative fields, from food to feed, from pharmaceutical to diagnostic, from agronomy to industry. Progress in organic chemistry allowed to obtain rather cheap compounds covering the whole color spectrum. However, several concerns arise from this chemical approach, as it is mainly based on nonrenewable resources such as fossil oil, and the toxicity or carcinogenic properties of products and/or precursors may be harmful for personnel involved in the productive processes. In this scenario, microorganisms and their pigments represent a colorful world to discover and reconsider. Each living bacterial strain may be a source of secondary metabolites with peculiar functions. The aim of this review is to link the physiological role of bacterial pigments with their potential use in different biotechnological fields. This enormous potential supports the big challenge for the development of strategies useful to identify, produce, and purify the right pigment for the desired application. At the end of this ideal journey through the world of bacterial pigments, the attention will be focused on melanin compounds, whose production relies upon different techniques ranging from natural producers, heterologous hosts, or isolated enzymes. In a green workflow, the microorganisms represent the starting and final point of pigment production.

Free and Poly-Methyl-Methacrylate-Bounded BODIPYs: Photodynamic and Antimigratory Effects in 2D and 3D Cancer Models.

Several limitations, including dark toxicity, reduced tumor tissue selectivity, low photostability and poor biocompatibility hamper the clinical use of Photodynamic therapy (PDT) in cancer treatment. To overcome these limitations, new PSs have been synthetized, and often combined with drug delivery systems, to improve selectivity and reduce toxicity. In this context, BODIPYs (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) have recently emerged as promising and easy-to-handle scaffolds for the preparation of effective PDT antitumor agents. In this study, the anticancer photodynamic effect of newly prepared negatively charged polymethyl methacrylate (nPMMA)-bounded BODIPYs (3@nPMMA and 6@nPMMA) was evaluated on a panel of 2D- and 3D-cultured cancer cell lines and compared with free BODIPYs. In particular, the effect on cell viability was evaluated, along with their ability to accumulate into the cells, induce apoptotic and/or necrotic cell death, and inhibit cellular migration. Our results indicated that 3@nPMMA and 6@nPMMA reduce cancer cell viability in 3D models of HC116 and MCF7 cells more effectively than the corresponding free compounds. Importantly, we demonstrated that MDA-MB231 and SKOV3 cell migration ability was significantly impaired by the PDT treatment mediated by 3@nPMMA and 6@nPMMA nanoparticles, likely indicating the capability of this approach to reduce metastatic tumor potential.

Photoinactivation of Pseudomonas aeruginosa Biofilm by Dicationic Diaryl-Porphyrin.

In recent years, antimicrobial photodynamic therapy (aPDT) has received increasing attention as a promising tool aimed at both treating microbial infections and sanitizing environments. Since biofilm formation on biological and inert surfaces makes difficult the eradication of bacterial communities, further studies are needed to investigate such tricky issue. In this work, a panel of 13 diaryl-porphyrins (neutral, mono- and di-cationic) was taken in consideration to photoinactivate Pseudomonas aeruginosa. Among cationic photosensitizers (PSs) able to efficiently bind cells, in this study two dicationic showed to be intrinsically toxic and were ruled out by further investigations. In particular, the dicationic porphyrin (P11) that was not toxic, showed a better photoinactivation rate than monocationic in suspended cells. Furthermore, it was very efficient in inhibiting the biofilms produced by the model microorganism Pseudomonas aeruginosa PAO1 and by clinical strains derived from urinary tract infection and cystic fibrosis patients. Since P. aeruginosa represents a target very difficult to inactivate, this study confirms the potential of dicationic diaryl-porphyrins as photo-activated antimicrobials in different applicative fields, from clinical to environmental ones.

Effect of blue light at 410 and 455 nm on Pseudomonas aeruginosa biofilm.

Pseudomonas aeruginosa is an opportunistic pathogen resistant to many antibiotics, able to form biofilm and causes serious nosocomial infections. Among anti-Pseudomonas light-based approaches, the recent antimicrobial Blue Light (aBL) treatment seems very promising. The aim of this study was to evaluate the efficiency of blue light in inhibiting and/or eradicating P. aeruginosa biofilm. Light at 410 nm has been identified as successful in inhibiting biofilm formation not only of the model strain PAO1, but also of CAUTI (catheter-associated urinary tract infection) isolates characterized by their ability to form biofilm. Results of this work on 410 nm light also demonstrated that: i) at the lowest tested radiant exposure (75 J cm-2) prevents matrix formation; ii) higher radiant exposures (225 and 450 J cm-2) light impairs the cellular components of biofilm, adherent and planktonic ones; iii) light eradicates with a good rate young and older biofilms in a light dose dependent manner; iv) it is also efficient in inactivating catalase A, a virulence factor playing an important role in pathogenic mechanisms. Light at 455 nm, even if at a lower extent than 410 nm, showed a certain anti-Pseudomonas activity. Furthermore, light at 410 nm caused detrimental effects on enzyme activity of ß-galactosidase and catalase A, and changes on plasmid DNA conformation and ortho-nitrophenyl-ß-D-galactopyranoside structure. This study supports the potential of blue light for anti-infective and disinfection applications.

Bacterial melanin production by heterologous expression of 4­hydroxyphenylpyruvate dioxygenase from Pseudomonas aeruginosa.

Pyomelanin is a reddish-brown pigment produced by bacteria of different genera and plays a variety of physiological roles. Proposals have been regarding the use of pyomelanin in various environmental, industrial and, more recently, cosmetic applications. In Pseudomonas aeruginosa, the enzyme 4­hydroxyphenylpiruvate dioxygenase (Hpd) converts 4-hydroxyphenylpiruvate into homogentisic acid, which represents the key intermediate for melanin biosynthesis. This work aimed to obtain Escherichia coli cells overexpressing hpd gene from the PAO1 strain to produce large amounts of pyomelanin for biotechnological purposes. The recombinant dioxygenase expression gave E. coli JM109 the ability to produce pyomelanin. A series of biotransformations led us to choose the best experimental conditions for pyomelanin production. Cells were grown at the mid-exponential phase in a mineral medium with added glucose 10 mM as carbon and energy sources and casamino acid 0.2% w/v as an amino acid source. The administration of tyrosine 1 mM after 30 min of exposure to arabinose 1% w/v made it possible to purify 213 mg/L of pyomelanin after 6 days of biotransformation. In addition to the interesting biotechnological outcomes, the resulting expression system supports the correlation between the hpd gene from P. aeruginosa PAO1 and pyomelanin synthesis.

AIF-1 and RNASET2 Play Complementary Roles in the Innate Immune Response of Medicinal Leech.

Recent studies demonstrated that allograft inflammatory factor-1 (AIF-1) and RNASET2 act as chemoattractants for macrophages and modulate the inflammatory processes in both vertebrates and invertebrates. The expression of these proteins significantly increases after bacterial infection; however, the mechanisms by which they regulate the innate immune response are still poorly defined. Here, we evaluate the effect of bacterial lipopolysaccharide injection on the expression pattern of these genes and the interrelation between them during innate immune response in the medicinal leech, an invertebrate model with a simple anatomy and a marked similarity with vertebrates in inflammatory processes. Collectively, prokaryotic-eukaryotic co-cultures and in vivo infection assays suggest that RNASET2 and AIF-1 play a crucial role in orchestrating a functional cross-talk between granulocytes and macrophages in leeches, resulting in the activation of an effective response against pathogen infection. RNASET2, firstly released by granulocytes, likely plays an early antibacterial role. Subsequently, AIF-1+ RNASET2-recruited macrophages further recruit other macrophages to potentiate the antibacterial inflammatory response. These experimental data are in keeping with the notion of RNA-SET2 acting as an alarmin-like molecule whose role is to locally transmit a "danger" signal (such as a bacterial infection) to the innate immune system in order to trigger an appropriate host response.

Anti-Pseudomonas activity of 3-nitro-4-phenylfuroxan.

Pseudomonas aeruginosa is a microorganism that is well adapted to both clinical and industrial settings, where it can form adherent communities that are difficult to eradicate. New anti-Pseudomonas compounds and strategies are necessary, as the current antimicrobial approaches for the inhibition of biofilm formation and, above all, the eradication of formed biofilms are ineffective. Compounds that belong to the furoxan family, which are well-known NO donors, have recently been shown to display anti-Pseudomonas activity. The present study investigates three furoxan compounds that are substituted at the hetero-ring with electron-withdrawing groups (NO2, CN, CONH2) for their effects on P. aeruginosa PAO1 growth and biofilm formation/dispersal. Of the furoxans tested, only 3-nitro-4-phenylfuroxan (KN455) inhibited the growth of suspended P. aeruginosa PAO1 cultures. Furthermore, KN455 inhibited the formation of both younger and older biofilms with very high yields and thus proved itself to be toxic to planktonic subpopulations. It also displayed moderate eradicating power. The activity of KN455 does not appear to be related to its capacity to release small amounts of NO. Interestingly, the isomer 4-nitro-3-phenylfuroxan (KN454), included for comparison, displayed a comparable antibiofilm rate, but did not show the same antimicrobial activity against suspended cells and planktonic subpopulations. While hypotheses as to the mechanism of action have been formulated, further investigations are necessary to shed light onto the antimicrobial activity of this furoxan.

Catalase A is involved in the response to photooxidative stress in Pseudomonas aeruginosa.

BACKGROUND: Pseudomonas aeruginosa is the etiological agent of systemic and skin infections that are often difficult to treat. Photodynamic therapy (PDT) and, more recently, phototherapy (PT), are emerging among antimicrobial treatments to be combined with antibiotics. Visible light, either alone or combined with a photosensitizer (PS), elicits photooxidative stress that induces microbial death. The response of bacteria to phototherapy seems to involve the antioxidant machinery. This study relies on the effects of detoxifying catalase A (KatA) in response to PDT and PT-induced photooxidative stress. METHODS: The photo- and photodynamic inactivation experiments have been targeted at P. aeruginosa PAO1 and its isogenic derivative katA- mutant. The microorganisms were irradiated by a wide-spectrum halogen-tungsten lamp or light-emitting diodes (LEDs). Two photosensitizers, Tetrakis-(1-methyl-4-pyridyl)-21H, 23porphine, tetra-p-tosylate (TMPyP) porphyrin and Toluidine Blue O (TBO), were applied as part of the photodynamic approach. RESULTS: P. aeruginosa katA- mutant was more sensitive than wild-type strain PAO1 to wide-spectrum light and blue LED (464 nm) treatments. The complementation of KatA, in katA- mutant, restored the light response of wild-type PAO1. Upon TBO treatment and irradiation by visible light (halogen lamp or LED), the sensitivity of katA- mutant was significant higher (p = 0.028 and p = 0.045, respectively) than that of the PAO1 strain. CONCLUSIONS: This study provides the first description of KatA in the response to photooxidative stress induced by photo- and photodynamic therapy.

Response to photo-oxidative stress of Pseudomonas aeruginosa PAO1 mutants impaired in different functions.

Clinicians often have to deal with infections that are difficult to control because they are caused by superbugs resistant to many antibiotics. Alternatives to antibiotic treatment include antimicrobial photodynamic therapy (aPDT). The photodynamic process causes bacterial death, inducing oxidative stress through the photoactivation of photosensitizer molecules in the presence of oxygen. No PDT-resistant bacteria have been selected to date, thus the response to photo-oxidative stress in non-phototrophic bacteria needs further investigation. The opportunistic pathogen Pseudomonas aeruginosa, in particular, has been shown to be more tolerant to PDT than other micro-organisms. In order to find any genetic determinants involved in PDT-tolerance, a panel of transposon mutants of P. aeruginosa PAO1 involved in the quorum sensing signalling system and membrane cytoplasmic transport were photoinactivated as part of this study. Two pseudomonas quinolone signalling (PQS) knock-out mutants, pqsH- and pqsC-, were as PDT-sensitive as the PAO1 wild-type strains. Two PQS hyperproducer variants, pqsA- and rsaL-, were shown to be more tolerant to photo-oxidative stress than the wild-type strain. In the pqsA- mutant, the hyperpigmentation due to the presence of phenazines could protect cells against PDT stress, while in rsaL- no pigmentation was detectable. Furthermore, a mutant impaired in an ATP-binding cassette transport involved in maintaining the asymmetry of the outer membrane was significantly more tolerant to photo-oxidative stress than the wild-type strain. These observations support the involvement of quorum sensing and the importance of the bacterial cell envelope when dealing with photo-oxidative stress induced by photodynamic treatment.

Honey-sensitive Pseudomonas aeruginosa mutants are impaired in catalase A.

The antimicrobial power of honey seems to be ascribable to several factors, including oxidative and osmotic stress. The aim of this study was to find genetic determinants involved in the response to honey stress in the opportunistic pathogen Pseudomonas aeruginosa, chosen as model micro-organism. A library of transposon mutants of P. aeruginosa PAO1 was constructed and only four mutants unable to grow in presence of fir honeydew honey were selected. All four mutants were impaired in the major H2O2-scavenging enzyme catalase A (KatA). The knockout of katA gene caused sensitivity, as expected, not only to hydrogen peroxide but also to different types of honey including Manuka GMO 220 honey. Genetic complementation, as well as the addition of PAO1 supernatant containing extracellular catalase, restored tolerance to honey stress in all the mutants. As P. aeruginosa PAO1 catalase KatA copes with H2O2 stress, it is conceivable that the antimicrobial activity of honey is, at least partially, due to the presence of hydrogen peroxide in honey or the ability of honey to induce production of hydrogen peroxide. The katA-deficient mutants could be used as tester micro-organisms to compare the power of different types of natural and curative honeys in eliciting oxidative stress mediated by hydrogen peroxide.

Pigments influence the tolerance of Pseudomonas aeruginosa PAO1 to photodynamically induced oxidative stress.

Pseudomonas aeruginosa is an opportunistic pathogen known to be resistant to different classes of antibiotics and disinfectants. P. aeruginosa also displays a certain degree of tolerance to photodynamic therapy (PDT), an alternative antimicrobial approach exploiting a photo-oxidative stress induced by exogenous photosensitizers and visible light. To evaluate whether P. aeruginosa pigments can contribute to its relative tolerance to PDT, we analysed the response to this treatment of isogenic transposon mutants of P. aeruginosa PAO1 with altered pigmentation. In general, in the presence of pigments a higher tolerance to PDT-induced photo-oxidative stress was observed. Hyperproduction of pyomelanin makes the cells much more tolerant to stress caused by either radicals or singlet oxygen generated by different photosensitizers upon photoactivation. Phenazines, pyocyanin and phenazine-1-carboxylic acid, produced in different amounts depending on the cultural conditions, are able to counteract both types of PDT-elicited reactive oxygen species. Hyperproduction of pyoverdine, caused by a mutation in a quorum-sensing gene, rendered P. aeruginosa more tolerant to a photosensitizer that generates mainly singlet oxygen, although in this case the observed tolerance to photo-oxidative stress cannot be exclusively attributed to the presence of the pigment.

Interaction between the inner nuclear membrane lamin B receptor and the heterochromatic methyl binding protein, MeCP2.

The nuclear membrane has an important role for the dynamic regulation of the genome, besides the well-established cytoskeletal function. The nuclear lamina is emerging as an important player in the organization of the position and functional state of interphase chromosomes. Epigenetic modifications such as DNA methylation and histone modifications are required for genome reprogramming during development, tissue-specific gene expression and global gene silencing. The Methyl-CpG binding protein MeCP2 binds methyl-CpG dinucleotides in the mammalian genome and functions as a transcriptional repressor in vivo by interacting with Sin3A, thereby recruiting histone deacetylases (HDAC). MeCP2 also mediates the formation of higher-order chromatin structures contributing to determine the architectural organization of the nucleus. In this paper, we show that MeCP2 interacts in vitro and in vivo with the inner nuclear membrane protein LBR and that the unstructured aminoacidic sequence linking the MBD and TRD domains of MeCP2 is responsible for this association. The formation of an LBR-MeCP2 protein complex might help providing a molecular explanation to the distribution of part of the heterochromatin at the nuclear periphery linked to inner membrane.

Functional consequences of mutations in CDKL5, an X-linked gene involved in infantile spasms and mental retardation.

Mutations in the X-linked cyclin-dependent kinase-like 5 (CDKL5) gene have been identified in patients with Rett syndrome, West syndrome, and X-linked infantile spasms sharing the common features of generally intractable early seizures and mental retardation. Disease-causing mutations are distributed in both the catalytic domain and in the large COOH terminus. In this report, we examine the functional consequences of some Rett mutations of CDKL5 together with some synthetically designed derivatives useful to underline the functional domains of the protein. The mutated CDKL5 derivatives have been subjected to in vitro kinase assays and analyzed for phosphorylation of the TEY (Thr-Glu-Tyr) motif within the activation loop, their subcellular localization, and the capacity of CDKL5 to interact with itself. Whereas wild-type CDKL5 autophosphorylates and mediates the phosphorylation of the methyl-CpG-binding protein 2 (MeCP2) in vitro, Rett-mutated proteins show both impaired and increased catalytic activity suggesting that a tight regulation of CDKL5 is required for correct brain functions. Furthermore, we show that CDKL5 can self-associate and mediate the phosphorylation of its own TEY (Thr-Glu-Tyr) motif. Eventually, we show that the COOH terminus regulates CDKL5 properties; in particular, it negatively influences the catalytic activity and is required for its proper sub-nuclear localization. We propose a model in which CDKL5 phosphorylation is required for its entrance into the nucleus whereas a portion of the COOH-terminal domain is responsible for a stable residency in this cellular compartment probably through protein-protein interactions.

Characterization of the human EDF-1 minimal promoter: involvement of NFY and Sp1 in the regulation of basal transcription.

Endothelial Differentiation Factor (EDF)-1 is a calmodulin binding protein involved in the repression of endothelial cell differentiation, a crucial, late step in angiogenesis. Its expression is cell cycle regulated, although its transcriptional regulation is yet to be determined. To map the promoter region and to understand its regulation, we cloned and fused 2300 bp upstream of EDF-1 translational start site to a luciferase reporter gene. After transient transfection in HeLa cells, this fragment was shown to possess a promoter activity. Deletion constructs of the 5' flanking region of EDF-1 lead to the identification of the minimal promoter region which was highly homologous to the mouse sequence. No TATA box was detected, whereas three consensus sequences--two GC boxes and a CAAT box--were identified. EMSA supershift and chromatin immunoprecipitation demonstrated that these sequences were binding sites for Sp1/Sp3 and NFY, respectively. Deletion of Sp1/Sp3 and NF-Y consensus sequences resulted in the total loss of EDF-1 promoter activity. Our studies indicate that Sp1 and NFY binding is essential for EDF-1 promoter activity.

The Pole3 bidirectional unit is regulated by MYC and E2Fs.

Pole3 (DPB4/YBL1/CHRAC17) is one of the subunits of the DNA polymerase e. It contains a histone-like domain required for the hererodimerization with its Pole4 (DPB3) partner. In another interaction, Pole3 heterodimerizes with YCL1/CHRAC15 and associates with the ACF1/SNF2H remodelling complex. We find that the Pol3 gene is regulated in starved NIH3T3 fibroblasts upon induction with serum, with a peak at the entry in the S phase. We characterized the Pole3 promoter, which is linked bidirectionally to C9Orf46, a gene of unknown function: it has no CCAAT nor TATA-boxes, and contains an E box and two potential E2F sites. Mutagenesis analysis points to a minimal promoter region as sufficient for activation; the E box and a neighbouring direct repeat are important for regulation. Cell-cycle regulation was reproduced in stable clones and an additional E2F site was found to be important. Chromatin immunoprecipitation analysis indicates that E2F1/4, as well as MYC, are associated with the Pole3 promoter in a phase-specific way. These data highlight coregulation of a histone-like gene with core histones upon DNA synthesis, and represent a first dissection of the interplay between two essential cell-cycle regulators on a bidirectional promoter.