UV-induced DNA damage is an intermediate step in UV-induced expression of human immunodeficiency virus type 1, collagenase, c-fos, and metallothionein

S2k‐Leitlinie: Diagnostik und Therapie der zirkumskripten Sklerodermie

Die vorliegende aktualisierte S2k‐Leitlinie befasst sich mit der Diagnostik und der Therapie der zirkumskripten Sklerodermie (ZS). Diese umfasst ein Spektrum sklerotischer Erkrankungen der Haut mit, je nach Subtyp und Lokalisation, möglicher Beteiligung von hautnahen Strukturen wie Fettgewebe, Muskulatur, Gelenke und Knochen. Ein Befall innerer Organe oder ein Übergang in eine systemische Sklerodermie treten nicht auf. Eingeteilt werden kann die ZS in die vier Hauptformen der limitierten, generalisierten, linearen und gemischten Form. Teilweise existieren weitere Unterformen. Bei limitiertem Hautbefall empfiehlt die Leitlinie primär eine Therapie mit topischen Kortikosteroiden. Eine UV‐Therapie kann ebenfalls sinnvoll sein. Bei Subtypen mit schwerem Hautbefall oder muskuloskelettalem Befall wird eine systemische Therapie mit Methotrexat empfohlen. In der aktiven Phase der Erkrankung können ergänzend systemische Glukokortikosteroide eingesetzt werden. Bei MTX‐ und Steroid‐refraktären Verläufen, Kontraindikation oder Unverträglichkeit sollten Mycophenolat‐Mofetil, Mycophenolsäure oder Abatacept als Systemtherapie der zweiten Wahl eingesetzt werden. Bei einer linearen ZS kann zudem eine autologe Fettstammzelltransplantation zur Korrektur von Weichteildefekten erfolgen.

Biochemically deleterious human NFKB1 variants underlie an autosomal dominant form of common variable immunodeficiency

Autosomal dominant (AD) NFKB1 deficiency is thought to be the most common genetic etiology of common variable immunodeficiency (CVID). However, the causal link between NFKB1 variants and CVID has not been demonstrated experimentally and genetically, as there has been insufficient biochemical characterization and enrichment analysis. We show that the cotransfection of NFKB1-deficient HEK293T cells (lacking both p105 and its cleaved form p50) with a κB reporter, NFKB1/p105, and a homodimerization-defective RELA/p65 mutant results in p50:p65 heterodimer–dependent and p65:p65 homodimer–independent transcriptional activation. We found that 59 of the 90 variants in patients with CVID or related conditions were loss of function or hypomorphic. By contrast, 258 of 260 variants in the general population or patients with unrelated conditions were neutral. None of the deleterious variants displayed negative dominance. The enrichment in deleterious NFKB1 variants of patients with CVID was selective and highly significant (P = 2.78 × 10⁻¹⁵). NFKB1 variants disrupting NFKB1/p50 transcriptional activity thus underlie AD CVID by haploinsufficiency, whereas neutral variants in this assay should not be considered causal.

The Gypsy Endogenous Retrovirus Drives Non-Cell-Autonomous Propagation in a Drosophila TDP-43 Model of Neurodegeneration

A hallmark of neurodegenerative disease is focal onset of pathological protein aggregation, followed by progressive spread of pathology to connected brain regions. In amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), pathology is often associated with aggregation of TAR DNA-binding protein 43 (TDP-43). Although aggregated TDP-43 protein moves between cells, it is not clear whether and how this movement propagates the degeneration. Here, we have established a Drosophila model of human TDP-43 in which we initiated toxic expression of human TDP-43 focally within small groups of glial cells. We found that this focal onset kills adjacent neurons. Surprisingly, we show that this spreading death is caused by an endogenous retrovirus within the glia, which leads to DNA damage and death in adjacent neurons. These findings suggest a possible mechanism by which human retroviruses such as HERV-K might contribute to TDP-43-mediated propagation of neurodegeneration.

Altered Expression Patterns of the Sumoylation Enzymes E1, E2 and E3 Are Associated with Glucose Oxidase- and UVA-Induced Cataractogenesis

PURPOSE

Protein sumoylation is a well established regulatory mechanism that regulates chromatin structure and dynamics, cell proliferation and differentiation, stress response and cell apoptosis. In the vertebrate eye, we and others have shown that sumoylation plays an indispensable role in regulating eye development. During stress induction and aging process, the ocular tissues gradually loss their normality and develop major ocular diseases such as cataract and aging-related macular degeneration. We have recently demonstrated that sumoylation actively regulates differentiation of lens cells, whether this process is implicated in lens pathogenesis remains to be investigated. In this study, we have demonstrated that transparent mouse lenses treated with glucose oxidase and UVA irradiation undergo in vitro cataract formation, and associated with this process, the expression patterns of the 3 sumoylation enzymes have been found significantly altered.

METHODS

Four-week-old C57BL/6J mice were used in our experiment. Lenses were carefully excised from eyes and cultured in M199 medium (Sigma 3769) for at least 12 hours. Transparent lenses (without surgical damage) were selected for experimentation. The lenses were exposed to UVA for 60 min or treated with 30 mU/mL glucose oxidase (GO, MP Biomedicals, 1673) to induce cataract formation. The mRNA levels were analysed with qRT-PCR. The protein levels were determined with western blot analysis and quantitated with Image J.

RESULTS

we have obtained the following results: 1) Both GO treatment and UVA irradiation can induce cataract formation in the in vitro cultured mouse lenses; 2) With GO treatment, the mRNAs and proteins for the 5 sumoylation enzymes were all significantly downregulated; 3) With UVA irradiation, the changes in the expression patterns of the mRNAs and proteins for the SAE1, UBA2 , UBC9 and PIAS1 were opposite, while the mRNAs were upregulated either significantly (for SAE1, UBA2 and UBC9) or slightly (PIAS1), the proteins for all 4 sumoylation enzymes were downregulated; For RanBP2, the UVA induced changes in both mRNA and protein are consist with the GO treatment.

CONCLUSION

Under GO and UVA irradiation conditions, the expression levels of both mRNA and protein for the three major sumoylation enzymes were significantly changed. Our results suggest that altered expression patterns of the sumoylation enzymes are associated with oxidative stressinduced cataractogenesis.

Genome Damage Sensing Leads to Tissue Homeostasis in Drosophila

DNA repair is a critical cellular process required for the maintenance of genomic integrity. It is now well appreciated that cells employ several DNA repair pathways to take care of distinct types of DNA damage. It is also well known that a cascade of signals namely DNA damage response or DDR is activated in response to DNA damage which comprise cellular responses, such as cell cycle arrest, DNA repair and cell death, if the damage is irreparable. There is also emerging literature suggesting a cross-talk between DNA damage signaling and several signaling networks within a cell. Moreover, cell death players themselves are also well known to engage in processes outside their canonical function of apoptosis. This chapter attempts to build a link between DNA damage, DDR and signaling from the studies mainly conducted in mammals and Drosophila model systems, with a special emphasis on their relevance in overall tissue homeostasis and development.

Identification of a second promoter in the human c-ets-2 proto-oncogene

We localized and characterized a new regulatory element with promoter activity in the human c-ets-2 intron 1. This promoter governs the expression of 5' divergent c-ets-2 transcripts through multiple start sites dispersed within 300 bp. Among the multiple start sites detected, three are major transcriptional initiation points. We detected transcripts initiated from this new promoter in various cell lines such as COLO 320, NBE, or HepG2 cells. This promoter exhibits transcriptional activity when linked to the CAT gene, and deletion constructs reveal that it contains activating and repressing elements. The sequence of the promoter reveals putative binding sites for ETS, MYB, GATA, and Oct factors. In addition, we show that this promoter is functionally conserved in the chicken.

Molecular Mechanism, Dynamics, and Energetics of Protein-Mediated Dinucleotide Flipping in a Mismatched DNA: A Computational Study of the RAD4-DNA Complex

DNA damage alters genetic information and adversely affects gene expression pathways leading to various complex genetic disorders and cancers. DNA repair proteins recognize and rectify DNA damage and mismatches with high fidelity. A critical molecular event that occurs during most protein-mediated DNA repair processes is the extrusion of orphaned bases at the damaged site facilitated by specific repairing enzymes. The molecular-level understanding of the mechanism, dynamics, and energetics of base extrusion is necessary to elucidate the molecular basis of protein-mediated DNA damage repair. The present article investigates the molecular mechanism of dinucleotide extrusion in a mismatched DNA (containing a stretch of three contiguous thymidine-thymidine base pairs) facilitated by Radiation sensitive 4 (RAD4), a key DNA repair protein, on an atom-by-atom basis using molecular dynamics (MD) and umbrella-sampling (US) simulations. Using atomistic models of RAD4-free and RAD4-bound mismatched DNA, the free energy profiles associated with extrusion of mismatched partner bases are determined for both systems. The mismatched bases adopted the most stable intrahelical conformation, and their extrusion was unfavorable in RAD4-free mismatched DNA due to the presence of prohibitively high barriers (>12.0 kcal/mol) along the extrusion pathways. Upon binding of RAD4 to the DNA, the global free energy minimum is shifted to the extrahelical state indicating the key role of RAD4-DNA interactions in catalyzing the dinucleotide base extrusion in the DNA-RAD4 complex. The critical residues of RAD4 contributing to the conformational stability of the mismatched bases are identified, and the energetics of insertion of a β-hairpin of RAD4 into the DNA duplex is examined. The conformational energy landscape-based mechanistic insight into RAD4-mediated base extrusion provided here may serve as a useful baseline to understand the molecular basis of xeroderma pigmentosum C (XPC)-mediated DNA damage repair in humans.

European Dermatology Forum S1-guideline on the diagnosis and treatment of sclerosing diseases of the skin, Part 1: localized scleroderma, systemic sclerosis and overlap syndromes

The term 'sclerosing diseases of the skin' comprises specific dermatological entities, which have fibrotic changes of the skin in common. These diseases mostly manifest in different clinical subtypes according to cutaneous and extracutaneous involvement and can sometimes be difficult to distinguish from each other. The present guideline focuses on characteristic clinical and histopathological features, diagnostic scores and the serum autoantibodies most useful for differential diagnosis. In addition, current strategies in the first- and advanced-line therapy of sclerosing skin diseases are addressed in detail. Part 1 of this guideline provides clinicians with an overview of the diagnosis and treatment of localized scleroderma (morphea), and systemic sclerosis including overlap syndromes of systemic sclerosis with diseases of the rheumatological spectrum.

German guidelines for the diagnosis and therapy of localized scleroderma

Localized scleroderma designates a heterogeneous group of sclerotic skin disorders. Depending on the subtype, severity, and site affected, adjacent structures such as adipose tissue, muscles, joints, and bones may be involved. This is an update of the existing German AWMF (Association of the Scientific Medical Societies in Germany) guidelines (classification: S2k). These guidelines provide an overview of the definition, epidemiology, classification, pathogenesis, laboratory workup, histopathology, clinical scoring systems, as well as imaging and device-based workup of localized scleroderma. Moreover, consensus-based recommendations are given on the management of localized scleroderma depending on its clinical subtype. Treatment recommendations are presented in a therapeutic algorithm. No financial support was given by any pharmaceutical company. The guidelines are valid until July 2019.

The role of Prdx6 in the protection of cells of the crystalline lens from oxidative stress induced by UV exposure

PURPOSE

The immediate aim of this study was to investigate alterations in peroxiredoxin (Prdx) 6 at posttranslational levels, and the levels of protein oxidation, lipid peroxidation, and reactive oxygen species (ROS) in lens epithelial cells (LECs) after exposure to severe oxidative stress, such as ultraviolet-B (UV-B). Our ultimate aim was to provide new information on antioxidant defenses in the lens and their regulation, thereby broadening existing knowledge of the role of Prdx6 in lens physiology and pathophysiology.

METHODS

The expression of the hyperoxidized form of Prdx6 and oxidation of protein were analyzed by western blotting and the OxyBlot assay in human LECs (hLECs). ROS levels were quantified using DCFH-DA dye, and cell viability was quantified by the MTS and TUNEL assays. To evaluate the protective effect of Prdx6, we cultured lenses with or without the TAT transduction domain (TAT-HA-Prdx6) and observed (and photographed) the cultures at specified time-points after the exposure to UV-B for the development of opacity.

RESULTS

Prdx6 in hLECs was hyperoxidized after exposure to high amounts of UV-B. UV-B treatment of hLECs increased the levels of cell death, protein oxidation, and ROS. hLECs exposed to UV-B showed higher levels of ROS, which could be reduced by the application of extrinsic TAT-HA-Prdx6, attenuating UV-B-induced lens opacity and apoptotic cell death.

CONCLUSION

Excessive oxidative stress induces the hyperoxidation of Prdx6 and may reduce the ability of Prdx6 to protect LECs against ROS or stresses. Because extrinsic Prdx6 could attenuate UV-B-induced abuse, this molecule may have a potential in preventing cataractogenesis.

The role of ultraviolet radiation in the pathogenesis of pterygia (Review)

Pterygium is a common ophthalmic disease affecting humans only. Extensive epidemiological data have demonstrated a causative effect of chronic ultraviolet (UV) radiation on pterygia. Progress has been made in determining the origin of pterygia, their nasal predilection and wing‑shaped appearance, and the roles of UV radiation in the initiation and the development of pterygia. In the present review, the current understanding of the involvement of UV radiation in the pathogenesis of pterygia is summarized. This involvement includes the alteration of limbal stem cells and fibroblasts that contribute to the initiation of pterygia and the induction of various pro‑inflammatory cytokines, growth factors and matrix metalloproteinases that promote the progression of pterygia. Further elucidation of the roles of UV radiation in the pathogenesis of pterygia may help to encourage individuals at risk of developing pterygia to take preventive measures and aid researchers in the development of novel targeted therapeutic agents to treat pterygia.

Current and future direction in the management of scleroderma

Scleroderma is a heterogeneous disease with a complex etiology. As more information is gained about the underlying mechanisms and the improved classifications of scleroderma subtypes, treatments can be better personalized. Improving scleroderma patients' early diagnosis before end organ manifestations occur should improve clinical trial design and outcomes. Two recently FDA-approved antifibrotics for idiopathic pulmonary fibrosis may be effective treatments in patients with pulmonary fibrosis secondary to scleroderma after further investigation. The potential impact of Nanobiotechnology in improving the efficacy and safety of existing antifibrotics and immunomodulators might present an exciting new approach in the management of scleroderma.

Alternative flow cytometry strategies to analyze stem cells and cell death in planarians

Planarians possess remarkable stem cell populations that continuously support cellular turnover and are instrumental in the regeneration of tissues upon injury. Cellular turnover and tissue regeneration in planarians rely on the proper integration of local and systemic signals that regulate cell proliferation and cell death. Thus, understanding the signals controlling cellular proliferation and cell death in planarians could provide valuable insights for maintenance of adult body homeostasis and the biology of regeneration. Flow cytometry techniques have been utilized widely to identify, isolate, and characterize planarian stem cell populations. We developed alternative flow cytometry strategies that reduce the number of reagents and the time of sample preparation to analyze stem cells and cell death in planarians. The sensitivity of these methods is validated with functional studies using RNA interference and treatment with  γ irradiation or stressful conditions that are known to trigger cell death. Altogether, we provide a community resource intended to minimize adverse effects during ex vivo studies of stem cells and cell death in planarians.

Conditioned medium from human bone marrow-derived mesenchymal stem cells promotes skin moisturization and effacement of wrinkles in UVB-irradiated SKH-1 hairless mice

BACKGROUND

Mesenchymal stem cells (MSCs) are promising therapeutic agents for various diseases.

AIMS

To investigate the effects of conditioned medium from human bone marrow-derived mesenchymal stem cells (MSC-CdM) on pro-collagen production and wrinkle formation, we performed in vitro and in vivo experiments.

METHODS

We assessed the effects of MSC-CdM on proliferation and photo-aging in human dermal fibroblasts after UVB exposure using enzyme activity assays for collagen type I secretion and MMP-1. To determine the effect of topically applied MSC-CdM on wrinkle formation, MSC-CdM (1% and 10%) and vehicle (propylene glycol: ethanol, 7 : 3) were applied to the dorsal skin of UVB-irradiated hairless mice for 8 weeks. We examined the effects on wrinkle formation by assessing visual skin grading, replica, tape stripping, transepidermal water loss (TEWL), and skin hydration measurement. We also examined histology of the lesions using hematoxylin-eosin, Masson's trichrome, and immunohistochemical staining.

RESULTS

MSC-CdM markedly reduced UV-induced matrix metalloproteinase-1 expression and increased pro-collagen synthesis in a dose-dependent manner. Our findings suggest that MSC-CdM induces repair of dermal damage and effacement of wrinkles on UVB-irradiated hairless mice through protective effect of hydration.

CONCLUSION

These results support an anti-wrinkle effect of MSC-CdM that involves increased collagen synthesis and suggest that MSC-CdM might be a potential candidate for preventing UV-induced skin damage.

Development and use of retinal pigmented epithelial cell line from zebrafish (Danio rerio) for evaluating the toxicity of ultraviolet-B

Danio rerio retinal pigmented epithelial (DrRPE) cell line, derived from the RPE tissue, was established and characterized. The cells were able to grow at a wide range of temperatures from 25°C to 32°C in Leibovitz's L-15 medium. The DrRPE cell line consists of epithelial cells with a diameter of 15-19 μm. The cell line was characterized by mitochondrial 12S rRNA gene, immunocytochemical analysis, and karyotyping. DrRPE cells treated with 10 μM of all-trans-retinol for 24 h readily formed lipid droplets. DrRPE cells were irradiated with narrowband ultraviolet-B (UV-B) radiation at different time periods of 0, 10, 20, and 40 min. The cells were subsequently examined for changes in morphology, cell viability, phagocytotic activity, mitochondrial distribution, nuclei morphology, generation of reactive oxygen species, and expression of apoptotic-related genes p53 and Cas3 by quantitative polymerase chain reaction. The results demonstrate that UV-B radiation can cause a considerable decrease in DrRPE cell viability as well as in phagocytotic activity. In addition, the results demonstrate that UV-B radiation can induce the degradation of mitochondria and DNA in cultured DrRPE cells.

Interplay of Rad51 with NF-κB pathway stimulates expression of HIV-1

Transcription from the HIV-1 promoter is controlled by a series of ubiquitous and inducible cellular proteins with the ability to enter the nucleus and interact with the promoter. A DNA sequence spanning nucleotides −120 to −80, which supports the association of the inducible NF-κB transcription factor, has received much attention. Here we demonstrate that the interplay between Rad51, a key regulator of the homologous recombination pathway of DNA repair and whose level is induced upon HIV-1 infection, with the NF-κB pathway, augments transcription of the viral promoter. Evidently, stimulation of the NF-κB pathway by PMA and/or TSA promotes association of Rad51 with the LTR DNA sequence and that the p65 subunit of NF-κB is important for this event. Our results also demonstrate that, similar to p65, Rad51 utilizes the NF-κB pathway to position itself in the nucleus as ectopic expression of an IκB mutant impedes its nuclear appearance and transcriptional activity upon the HIV-1 LTR. Treatment of peripheral blood mononuclear cells with small molecules that inhibit Rad51 activity results in greater than 50% decrease in the HIV-1 infection of cells. These observations provide evidence for the involvement of DNA repair factors in control of HIV-1 gene activation and offer a new avenue for the development of anti-viral therapeutics that affect viral gene transcription in latently infected cells.

Updates on morphea: role of vascular injury and advances in treatment

Morphea and systemic sclerosis are fibrosing disorders of the skin that share common inflammatory and immunologic pathways that are responsible for the vascular changes, increased collagen production, and extracellular matrix proliferation seen in both conditions. Recent advances in molecular biology techniques have furthered our knowledge of the potential underlying pathogenic mechanisms and offer new and provocative areas of research for novel diagnostic and therapeutic interventions. This review focuses on the role of vascular injury in the development of morphea, the use of ultrasonography as a diagnostic modality, and well-established and newly proposed treatments.

Expression patterns of RelA and c-mip are associated with different glomerular diseases following anti-VEGF therapy

Renal toxicity constitutes a dose-limiting side effect of anticancer therapies targeting vascular endothelial growth factor (VEGF). In order to study this further, we followed up 29 patients receiving this treatment, who experienced proteinuria, hypertension, and/or renal insufficiency. Eight developed minimal change nephropathy/focal segmental glomerulopathy (MCN/FSG)-like lesions and 13 developed thrombotic microangiopathy (TMA). Patients receiving receptor tyrosine kinase inhibitors (RTKIs) mainly developed MCN/FSG-like lesions, whereas TMA complicated anti-VEGF therapy. There were no mutations in factor H, factor I, or membrane cofactor protein of the complement alternative pathway, while plasma ADAMTS13 activity persisted and anti-ADAMTS13 antibodies were undetectable in patients with TMA. Glomerular VEGF expression was undetectable in TMA and decreased in MCN/FSG. Glomeruli from patients with TMA displayed a high abundance of RelA in endothelial cells and in the podocyte nuclei, but c-mip was not detected. Conversely, MCN/FSG-like lesions exhibited a high abundance of c-mip, whereas RelA was scarcely detected. RelA binds in vivo to the c-mip promoter and prevents its transcriptional activation, whereas RelA knockdown releases c-mip activation. The RTKI sorafenib inhibited RelA activity, which then promoted c-mip expression. Thus, our results suggest that c-mip and RelA define two distinct types of renal damage associated with VEGF-targeted therapies.

NF-κB-dependent role for cold-inducible RNA binding protein in regulating interleukin 1β

The cold inducible RNA binding protein (CIRBP) responds to a wide array of cellular stresses, including short wavelength ultraviolet light (UVC), at the transcriptional and post-translational level. CIRBP can bind the 3'untranslated region of specific transcripts to stabilize them and facilitate their transport to ribosomes for translation. Here we used RNA interference and oligonucleotide microarrays to identify potential downstream targets of CIRBP induced in response to UVC. Twenty eight transcripts were statistically increased in response to UVC and these exhibited a typical UVC response. Only 5 of the 28 UVC-induced transcripts exhibited a CIRBP-dependent pattern of expression. Surprisingly, 3 of the 5 transcripts (IL1B, IL8 and TNFAIP6) encoded proteins important in inflammation with IL-1β apparently contributing to IL8 and TNFAIP6 expression in an autocrine fashion. UVC-induced IL1B expression could be inhibited by pharmacological inhibition of NFκB suggesting that CIRBP was affecting NF-κB signaling as opposed to IL1B mRNA stability directly. Bacterial lipopolysaccharide (LPS) was used as an activator of NF-κB to further study the potential link between CIRBP and NFκB. Transfection of siRNAs against CIRBP reduced the extent of the LPS-induced phosphorylation of IκBα, NF-κB DNA binding activity and IL-1β expression. The present work firmly establishes a novel link between CIRBP and NF-κB signaling in response to agents with diverse modes of action. These results have potential implications for disease states associated with inflammation.

Localized scleroderma

Localized scleroderma (also called morphea) is a term encompassing a spectrum of sclerotic autoimmune diseases that primarily affect the skin, but also might involve underlying structures such as the fat, fascia, muscle, and bones. Its exact pathogenesis is still unknown, but several trigger factors in genetically predisposed individuals might initially lead to an immunologically triggered release of pro-inflammatory cytokines, resulting in a profound dysregulation of the connective tissue metabolism and ultimately to induction of fibrosis. To date, there are no specific serological markers available for localized scleroderma. Within the last years, several validated clinical scores have been introduced as potential outcome measures for the disease. Given the rarity of localized scleroderma, only few evidence-based therapeutical treatment options exist. So far, the most robust data is available for ultraviolet A1 phototherapy in disease that is restricted to the skin, and methotrexate alone or in combination with systemic corticosteroids in more severe disease that additionally affects extracutaneous structures. This practical review summarizes relevant information on the epidemiology, pathogenesis, clinical subtypes and classifications, differential diagnoses, clinical scores and outcome measures, and current treatment strategies of localized scleroderma.

DNA damage-dependent NF-κB activation: NEMO turns nuclear signaling inside out

The dimeric transcription factor nuclear factor κB (NF-κB) functions broadly in coordinating cellular responses during inflammation and immune reactions, and its importance in the pathogenesis of cancer is increasingly recognized. Many of the signal transduction pathways that trigger activation of cytoplasmic NF-κB in response to a broad array of immune and inflammatory stimuli have been elaborated in great detail. NF-κB can also be activated by DNA damage, though relatively less is known about the signal transduction mechanisms that link DNA damage in the nucleus with activation of NF-κB in the cytoplasm. Here, we focus on the conserved signaling pathway that has emerged that promotes NF-κB activation following DNA damage. Post-translational modification of NF-κB essential modulator (NEMO) plays a central role in linking the cellular DNA damage response to NF-κB via the ataxia telangiectasia mutated (ATM) kinase. Accumulating evidence suggests that DNA damage-dependent NF-κB activation may play significant biological roles, particularly during lymphocyte differentiation and progression of human malignancies.

Protein kinases and transcription factors activation in response to UV-radiation of skin: implications for carcinogenesis

Solar ultraviolet (UV) radiation is an important environmental factor that leads to immune suppression, inflammation, photoaging, and skin carcinogenesis. Here, we reviewed the specific signal transduction pathways and transcription factors involved in the cellular response to UV-irradiation. Increasing experimental data supporting a role for p38, MAPK, JNK, ERK1/2, and ATM kinases in the response network to UV exposure is discussed. We also reviewed the participation of NF-κB, AP-1, and NRF2 transcription factors in the control of gene expression after UV-irradiation. In addition, we discussed the promising chemotherapeutic intervention of transcription factors signaling by natural compounds. Finally, we focused on the review of data emerging from the use of DNA microarray technology to determine changes in global gene expression in keratinocytes and melanocytes in response to UV treatment. Efforts to obtain a comprehensive portrait of the transcriptional events regulating photodamage of intact human epidermis after UV exposure reveals the existence of novel factors participating in UV-induced cell death. Progress in understanding the multitude of mechanisms induced by UV-irradiation could lead to the potential use of protein kinases and novel proteins as specific targets for the prevention and control of skin cancer.

In vitro ultraviolet-induced damage in human corneal, lens, and retinal pigment epithelial cells

PURPOSE

The purpose was to develop suitable in vitro methods to detect ocular epithelial cell damage when exposed to UV radiation, in an effort to evaluate UV-absorbing ophthalmic biomaterials.

METHODS

Human corneal epithelial cells (HCEC), lens epithelial cells (HLEC), and retinal pigment epithelial cells (ARPE-19) were cultured and Ultraviolet A/Ultraviolet B (UVA/UVB) blocking filters and UVB-only blocking filters were placed between the cells and a UV light source. Cells were irradiated with UV radiations at various energy levels with and without filter protections. Cell viability after exposure was determined using the metabolic dye alamarBlue and by evaluating for changes in the nuclei, mitochondria, membrane permeability, and cell membranes of the cells using the fluorescent dyes Hoechst 33342, rhodamine 123, calcein AM, ethidium homodimer-1, and annexin V. High-resolution images of the cells were taken with a Zeiss 510 confocal laser scanning microscope.

RESULTS

The alamarBlue assay results of UV-exposed cells without filters showed energy level-dependent decreases in cellular viability. However, UV treated cells with 400 nm LP filter protection showed the equivalent viability to untreated control cells at all energy levels. Also, UV irradiated cells with 320 nm LP filter showed lower cell viability than the unexposed control cells, yet higher viability than UV-exposed cells without filters in an energy level-dependent manner. The confocal microscopy results also showed that UV radiation can cause significant dose-dependent degradations of nuclei and mitochondria in ocular cells. The annexin V staining also showed an increased number of apoptotic cells after UV irradiation.

CONCLUSIONS

The findings suggest that UV-induced HCEC, HLEC, and ARPE-19 cell damage can be evaluated by bioassays that measure changes in the cell nuclei, mitochondria, cell membranes, and cell metabolism, and these assay methods provide a valuable in vitro model for evaluating the effectiveness of UV-absorbing ophthalmic biomaterials, including contact lenses and intraocular lenses.

Nuclear initiated NF-κB signaling: NEMO and ATM take center stage

A large body of literature describes elaborate NF-κB signaling networks induced by inflammatory and immune signals. Decades of research has revealed that transcriptionally functional NF-κB dimers are activated by two major pathways, canonical and non-canonical. Both pathways involve the release of NF-κB dimers from inactive cytoplasmic complexes to cause their nuclear translocation to modulate gene expression programs and biological responses. NF-κB is also responsive to genotoxic agents; however, signal communication networks that are initiated in the nucleus following DNA damage induction are less defined. Evidence in the literature supports the presence of such signaling pathways induced by multiple distinct genotoxic agents, resulting in the activation of cytoplasmic IKK complex. An example is a pathway that involves the DNA damage-responsive kinase ataxia telangiectasia mutated (ATM) and a series of post-translational modifications of NF-κB essential modulator (NEMO) in the nucleus of a genotoxin-exposed cell. Recent evidence also suggests that this nuclear-initiated NF-κB signaling pathway plays significant physiological and pathological roles, particularly in lymphocyte development and human cancer progression. This review will summarize these new developments, while identifying significant unanswered questions and providing new hypotheses that may be addressed in future studies.

Molecular mechanisms of ultraviolet radiation-induced DNA damage and repair

DNA is one of the prime molecules, and its stability is of utmost importance for proper functioning and existence of all living systems. Genotoxic chemicals and radiations exert adverse effects on genome stability. Ultraviolet radiation (UVR) (mainly UV-B: 280-315 nm) is one of the powerful agents that can alter the normal state of life by inducing a variety of mutagenic and cytotoxic DNA lesions such as cyclobutane-pyrimidine dimers (CPDs), 6-4 photoproducts (6-4PPs), and their Dewar valence isomers as well as DNA strand breaks by interfering the genome integrity. To counteract these lesions, organisms have developed a number of highly conserved repair mechanisms such as photoreactivation, base excision repair (BER), nucleotide excision repair (NER), and mismatch repair (MMR). Additionally, double-strand break repair (by homologous recombination and nonhomologous end joining), SOS response, cell-cycle checkpoints, and programmed cell death (apoptosis) are also operative in various organisms with the expense of specific gene products. This review deals with UV-induced alterations in DNA and its maintenance by various repair mechanisms.

Differential expression of novH and CTGF in human glioma cell lines

Aims-(1) To investigate the expression in human derived glioblastoma cell lines of two structurally related genes, novH (nephroblastoma overexpressed gene) and CTGF (connective tissue growth factor), which encode putative insulin-like growth factor binding proteins of a novel type. (2) To investigate whether the same transcription factors regulate CTGF and novH expression.Methods-Expression of novH and CTGF was analysed in 24 glioblastoma derived cell lines by northern blotting. The CTGF promoter region was characterised by nucleotide sequencing, RNase protection experiments, by transient transfections, and CAT assays.Results-CTGF and novH mRNA levels differed in the glioma cell lines studied. NovH and CTGF genes were not co-expressed in all cell lines. The CTGF promoter region was highly conserved compared with the corresponding region in the mouse (FISP12) and exhibited in vitro transcriptional activity.Conclusions-Although the coding regions of novH and CTGF are highly homologous, their promoter regions are substantially different, suggesting that these two genes may be regulated by different mechanisms. Considering that novH and CTGF are likely to be, respectively, negative and positive regulators of growth and that some glioma cell lines expressing novH are not tumorigenic, expression of these two genes might represent a key element in determining the stage of differentiation or the malignant potential, or both, of some tumour cell lines.

Expression and regulation of vitamin D3 upregulated protein 1 (VDUP1) is conserved in mammalian and insect brain

Originally characterized as a cell-cycle inhibitor induced by vitamin D(3), the tumor suppressor vitamin-D(3) upregulated protein 1 (VDUP1) has increasingly been shown to play major physiological roles in cell differentiation and glucose metabolism. Here we show evolutionarily conserved expression patterns of VDUP1 in Drosophila and rat nervous systems, including subcellular localization--cytoplasmic enrichment in neurons and nuclear expression in glia. These anatomical correlates suggested conservation of VDUP1 regulation, which was investigated both functionally and through promoter studies. Characterization of orthologous vdup1 cis-regulatory regions identified evolutionarily conserved sequence blocks (CSBs) with similarities to neural enhancers, including basic helix-loop-helix (bHLH) transcription factor Neurogenin/Math/atonal and Mash/achaete-scute family members. E-boxes (CANNTG), the binding sites for bHLH proteins, were associated with these CSBs as well, including E-boxes known to mediate glucose-dependent upregulation of VDUP1 in nonneuronal cells. Hyperglycemia-induced upregulation of VDUP1 was observed in brain tumor cells and in the Drosophila nervous system, which resulted in developmental arrest. Taken together, these data demonstrate evolutionary conservation of VDUP1 regulation and function, and suggest an expanding role for VDUP1 in nervous system development.

AP-1--The Jun proteins: Oncogenes or tumor suppressors in disguise?

Since its discovery more than two decades ago the involvement of the Activating protein 1 (AP-1) in proliferation, inflammation, differentiation, apoptosis, cellular migration and wound healing has been intensively studied. A model based on the early studies suggested antagonistic roles for the Jun proteins in proliferation and transformation. c-Jun was suggested to enhance transformation whereas JunB suggested to inhibit it in an antagonistic manner. Surprisingly, despite accumulation of data obtained from animal models regarding the role of Jun proteins in cancer and identification of oncogenic pathways regulating them, their involvement in human cancer was not demonstrated until recently. Here, we will describe the current knowledge about the roles of Jun proteins in human neoplasia. We will focus on the pathological examples demonstrating that the initial dogma has to be reexamined. For example, like c-Jun, JunB seems to play an oncogenic role in lymphomas, particularly in Hodgkin's lympomas. Furthermore, unlike the antagonistic activities of c-Jun and JunB in the transcription of genes coding for major cell cycle regulators such as CyclinD or p16INK4A, the transcription of other cell cycle regulating genes is modified similarly by c-Jun or JunB. Interestingly, some of these genes such as the ones coding for CyclinA or p19(ARF) are important players in either positive or negative regulation of cellular proliferation and survival. Finally, we will also discuss results posing JNK, known so far as the major activator of c-Jun, as a negative regulator of c-Jun level and activity. These recent findings suggest that the role of each Jun protein in neoplasia as well as in cellular survival should be examined in a context-dependent manner.

A PAR-SUMOnious mechanism of NEMO activation

In this issue of Molecular Cell, Stilmann et al. (2009) demonstrate a new mode of prosurvival NF-kappaB activation through the formation of a PARP-1-poly(ADP-ribose) signaling scaffold in response to DNA damage.

Ag and Cu loaded on TiO2/graphite as a catalyst for Escherichia coli-contaminated water disinfection

TiO2 film was synthesized by means of the chemical bath deposition (CBD) method from TiCl4 as a precursor and surfactant cetyl trimethyl ammonium bromide (CTAB) as a linking and assembling agent of the titanium hydroxide network on a graphite substrate. Ag and Cu were loaded on the TiO2 film by means of electrodeposition at various applied currents. Photoelectrochemical testing on the composite of Ag-TiO2/G and Cu-TiO2/G was used to define the composite for Escherichia coli-contaminated water disinfection. Disinfection efficiency and the rate of disinfection of E. coli-contaminated water with Ag-TiO2/G as a catalyst was higher than that observed for Cu-TiO2/G in all disinfection methods including photocatalysis (PC), electrocatalysis (EC), and photoelectrocatalysis (PEC). The highest rate constant was achieved by the PEC method using Ag-TiO2/G, k was 6.49 × 10−2 CFU mL−1 min−1. Effective disinfection times of 24 h (EDT24) and 48 h (EDT48) were achieved in all methods except the EC method using Cu-TiO2/G.

[AWMF Guideline no. 013/066. Diagnosis and therapy of circumscribed scleroderma]

Localized scleroderma is a rare autoimmune disease with primary affection of the skin, and occasional involvement of the fat tissue, muscle, fascia, and bone. Depending on the clinical subtype, the spectrum of skin lesions ranges from singular plaque lesions to severe generalized or linear subtypes which may lead to movement restrictions and permanent disability. This German S1-guideline proposes a classification of localized scleroderma that, considering the extent and depth of fibrosis, distinguishes limited, generalized, linear, and deep forms of localized scleroderma, together with its associated subtypes. The guideline includes a description of the pathogenesis, of differential diagnoses, and particular aspects of juvenile localized scleroderma, as well as recommendations for histopathologic, serologic, and biometric diagnostic procedures. Based on studies of topical and systemic treatments as well as phototherapy for localized scleroderma published in international literature, a treatment algorithm was developed which takes account of the different subtypes and the extent of disease.

Induced Accumulation of Polyubiquitin Gene Transcripts in HeLa Cells after UV-irradiation and TPA-treatment

There are three species of ubiquitin gene transcripts in HeLa cells, termed UbA (approximately 0.7 kb), UbB (approximately 1.1 kb) and UbC (approximately 2.5 kb). In the present report, the UbC transcript was shown to accumulate up to 2.5-fold after irradiation with UV light or treatment with the phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA). The kinetic analysis indicated that the induced accumulation of UbC was rapid and transient; maximal accumulation of UbC was induced at 2.5 h after UV irradiation or 3 h after TPA treatment. Inhibition of a de novo protein synthesis by cycloheximide did not repress the induction of UbC after treatment with UV light and TPA. On the other hand, induction of UbA and UbB, in most cases, was not observed. UV-inducibility of human ubiquitin conjugating enzyme, E2(17k), was also tested. E2(17k) is a protein with high sequence similarity to the product of yeast DNA repair gene, RAD6. While the RAD6 gene has been reported to be inducible by UV light, no change in E2(17k) gene transcript was observed after UV irradiation.

Ultraviolet B and A irradiation induces fibromodulin expression in human fibroblasts in vitro

Ultraviolet (UV) radiation affects the extracellular matrix (ECM) of the human skin. The small leucine-rich repeat protein fibromodulin interacts with type I and II collagen fibrils, thereby affecting ECM assembly. The aim of this study was to evaluate whether short wave UV (UVB) or long wave UV (UVA) irradiation influences fibromodulin expression. Exponentially growing human fibroblasts (IMR-90 cells) were exposed to increasing doses of UVB (2.5-60 mJ/cm(2)) or UVA (0.5-10 J/cm(2)). After UV irradiation fibromodulin, p21 and GADD45 levels were evaluated as well as cell viability, reactive oxygen species formation (ROS) and DNA damage. We found that fibromodulin expression: (i) increased after UVB and UVA irradiation; (ii) was 10-fold higher after UVA (10 J/cm(2)) versus 5-fold with UVB (10 mJ/cm(2)); (iii) correlated with reactive oxygen species formation, particularly after UVA; and (iv) was linked to the DNA damage binding protein (DDB1) translocation in the nucleus, particularly after UVB. These results further suggest that the UV-induced fibromodulin increase could counteract the UV-induced connective tissue damage, promoting the assembly of new collagen fibrils.

Regulation of C/EBPdelta-dependent transactivation by histone deacetylases in intestinal epithelial cells

The C/EBPdelta transcription factor is involved in the positive regulation of the intestinal epithelial cell acute phase response. C/EBPdelta regulation by histone deacetylases (HDACs) during the course of inflammation remains to be determined. Our aim was to examine the effect of HDACs on C/EBPdelta-dependent regulation of haptoglobin, an acute phase protein induced in intestinal epithelial cells in response to pro-inflammatory cytokines. HDAC1, HDAC3, and HDAC4 were expressed in intestinal epithelial cells, as determined by Western blot. GST pull-down assays showed specific HDAC1 interactions with the transcriptional activation and the b-ZIP C/EBPdelta domains, while the co-repressor mSin3A interacts with the C-terminal domain. Immunoprecipitation assays confirmed the interaction between HDAC1 and the N-terminal C/EBPdelta amino acid 36-164 domain. HDAC1 overexpression decreased C/EBPdelta transcriptional activity of the haptoglobin promoter, as assessed by transient transfection and luciferase assays. Chromatin immunoprecipitation analysis showed a displacement of HDAC1 from the haptoglobin promoter in response to inflammatory stimuli and an increased acetylation of histone H3 and H4. HDAC1 silencing by shRNA expression increased both basal and IL-1beta-induced haptoglobin mRNA levels in epithelial intestinal cells. Our results suggest that interactions between C/EBPs and HDAC1 negatively regulate C/EBPdelta-dependent haptoglobin expression in intestinal epithelial cells.

UV-induced DNA damage initiates release of MMP-1 in human skin

Destruction of collagen is a hallmark of photoaging. The major enzyme responsible for collagen 1 digestion, matrix metalloproteinase-1 (MMP-1), is induced by exposure to sunlight. To study the molecular trigger for this induction, human skin was ultraviolet-B (UVB)-irradiated and treated with liposome-encapsulated DNA repair enzymes. The photolyase-mediated DNA repair of epidermal UV damage was associated with a reduction of MMP-1 mRNA and protein expression in both the epidermal and dermal compartments of the skin. The role of the epidermal cells in MMP-1 induction in the fibroblasts was examined when human epidermal keratinocytes were irradiated with UVB and their media were transferred to unirradiated human dermal fibroblasts. Transfer of media from irradiated keratinocytes to unirradiated fibroblasts enhanced MMP-1 mRNA and protein. Thus, UV damage to keratinocytes of the epidermis may participate in the destruction of collagen in the dermis by release of soluble mediators that signal fibroblasts to release MMP-1. The MMP-1 induction was reduced when the keratinocytes were treated with DNA repair enzymes T4 endonuclease V or UV endonuclease prior to transfer of the media to fibroblasts. This implies that UVB, which deposits most of its energy on the chromatin of the epidermal keratinocytes and to a lesser extent in the upper dermis, has a significant role in photoaging. DNA damage in the keratinocytes initiates one of the signals for MMP-1 release, and enhancing DNA repair can reduce MMP-1 expression in human skin cells and tissue.

Supreme EnLIGHTenment: damage recognition and signaling in the mammalian UV response

Like their prokaryotic counterparts, mammalian cells can sense light, especially in the ultraviolet (UV) range of the spectrum. After UV exposure, cells mount an elaborate response--called the UV response--that mimics physiological signaling responses except that it targets multiple pathways, thereby lacking the defined specificity of receptor-triggered signal transduction. Despite many years of research, it is still not fully clear how UV radiation is sensed and converted into the "language of cells"--signal reception and transduction. This review focuses on how photonic energy and its primary cellular products are sensed to elicit the UV response.

Cyclosporin A inhibits HTLV-I tax expression and shows anti-tumor effects in combination with VP-16

Adult T cell leukemia (ATL) is one of the most refractory malignant hematological diseases. Our previous studies demonstrated HTLV-1Tax protein involvement in clinical manifestation of the aggressive type of ATL and suggested the potential application of agents to inhibit Tax expression for ATL treatment. In the present study, we first examined Tax involvement in the resistance to VP-16-induced apoptosis using four HTLV-1 infected T cell clones and cTax DNA-transfected cells. Next, we examined whether cyclosporin A reduced expression of Tax and its related transfer factors on Western blot and CAT assay. We further investigated whether cyclosporin A in combination with VP-16 can induce apoptosis in HTLV-1 infected T cells. Tax-producing T cells, K3T and F6T, were resistant to VP-16 induced growth inhibition compared with that of the nonproducing cells, S1T and Su9T01. Experiments using S1T and Tax-expressing cDNA-transfected S1T demonstrated Tax-induced resistance to VP-16 induction of apoptosis by DNA ladder formation. Cyclosporin A reduced Tax expression in K3T by Western blot analysis and on CAT assay, showing maximal reduction of 61% and 60% compared to control culture using LTR CAT transfected Jurkat cells and K3T cells, respectively. Cyclosporin A also reduced the nuclear expression of two Tax-related transfer factors, ATF-1 and ATF-2 on Western blot. Cyclosporin A alone did not show any cytotoxicity by itself, but sensitized cells to VP-16 when combined with VP-16. Cyclosporin A may be a useful anti-ATL agent when combined with other anti-cancer agents possibly related to Tax inhibition.

Detection of UV-induced activation of NF-kappaB in a recombinant human cell line by means of Enhanced Green Fluorescent Protein (EGFP)

The cellular protection reaction known as ultraviolet (UV) response leads to increased transcription of several genes. Parts of this transcriptional response are transmitted via activation of the Nuclear factor kappaB (NF-kappaB). The contribution of different UV radiation qualities to this process is not yet known. In a previous work, a stably transfected human cell line was developed which indicates activation of the NF-kappaB pathway by fluorescence of the reporters Enhanced Green Fluorescent Protein (EGFP) and its destabilized variant (d2EGFP) thereby allowing a fast and reliable monitoring of UV effects on the NF-kappaB pathway. Cells were exposed to a mercury low-pressure lamp or to simulated sunlight of different wavelength ranges and subjected to flow cytometric analysis after different post-irradiation periods. Growth capacity of cells after UV irradiation was quantified using a luminance measurement of crystal violet stained cell layers. In contrast to UVC and UVB, UVA radiation induced d2EGFP expression and NF-kappaB activation in a non-cytotoxic dose range. These results show that NF-kappaB plays a role in the UVA-induced gene activation in a non-cytotoxic dose range in a human epithelial cell line.

Many faces of NF-kappaB signaling induced by genotoxic stress

The nuclear factor-kappaB (NF-kappaB) family of dimeric transcription factors plays pivotal roles in physiologic and pathologic processes, including immune and inflammatory responses and development and progression of various human cancers. Inactive NF-kappaB dimers normally exist in the cytoplasm in association with inhibitor proteins belonging to the inhibitor of NF-kappaB (IkappaB) family of related proteins. Activation of NF-kappaB involves its release from IkappaB and subsequent nuclear translocation to induce expression of target genes. Intense research effort has revealed many distinct signaling pathways and mechanisms of NF-kappaB activation induced by immune and inflammatory stimuli. These aspects of NF-kappaB biology have been amply reviewed in the literature. However, those that involve DNA-damaging agents are less well understood, and multiple conflicting pathways and mechanisms have been described in the literature. In this review, we summarize the proposed mechanisms of NF-kappaB activation by various DNA-damaging agents, discuss the significance of such activation in the context of cancer treatment, and highlight some of the critical questions that remain to be addressed in future studies.

Dual effect of butyrate on IL-1beta--mediated intestinal epithelial cell inflammatory response

Butyrate (NaBu), a product of intestinal microbial metabolism, has been proposed as an anti-inflammatory agent for treating inflammatory bowel diseases. However, the molecular mechanisms implicated in the modulation of intestinal epithelial cell inflammatory response to NaBu remain unknown. Here, microarray analysis performed on nontransformed human crypt intestinal epithelial cells (HIEC) shows that NaBu regulated specifically the short-term IL-1beta -dependent induction of different inflammatory genes. While NaBu significantly increased the IL-1beta -induction of genes like SAA2, C3, and IL-1alpha , other inflammatory genes like CXCL5, CXCL11, and IL-1beta were decreased. Induction of various genes such as CXCL8, CCL20, and IL-6 was unaffected by NaBu. We show that, compared to genes that are upregulated or downregulated by NaBu, genes that are unaffected by NaBu were induced more rapidly after IL-1beta treatment and contained a higher concentration of transcription factor binding sites in their promoter region. In addition, transient treatment with IL-1beta was sufficient for subsequent induction of NaBu-upregulated and NaBu-unaffected classes of genes, while a continuous presence of IL-1beta was required for NaBu-downregulated gene expression. In conclusion, our results suggest that fundamental differences predispose inflammatory genes to specific regulation by NaBu in intestinal epithelial cells, thereby allowing precise control of inflammation.