Dendritic Cells Revisited.

Dendritic cells (DCs) possess the ability to integrate information about their environment and communicate it to other leukocytes, shaping adaptive and innate immunity. Over the years, a variety of cell types have been called DCs on the basis of phenotypic and functional attributes. Here, we refocus attention on conventional DCs (cDCs), a discrete cell lineage by ontogenetic and gene expression criteria that best corresponds to the cells originally described in the 1970s. We summarize current knowledge of mouse and human cDC subsets and describe their hematopoietic development and their phenotypic and functional attributes. We hope that our effort to review the basic features of cDC biology and distinguish cDCs from related cell types brings to the fore the remarkable properties of this cell type while shedding some light on the seemingly inordinate complexity of the DC field.

Distinct ontogenetic lineages dictate cDC2 heterogeneity.

Conventional dendritic cells (cDCs) include functionally and phenotypically diverse populations, such as cDC1s and cDC2s. The latter population has been variously subdivided into Notch-dependent cDC2s, KLF4-dependent cDC2s, T-bet+ cDC2As and T-bet- cDC2Bs, but it is unclear how all these subtypes are interrelated and to what degree they represent cell states or cell subsets. All cDCs are derived from bone marrow progenitors called pre-cDCs, which circulate through the blood to colonize peripheral tissues. Here, we identified distinct mouse pre-cDC2 subsets biased to give rise to cDC2As or cDC2Bs. We showed that a Siglec-H+ pre-cDC2A population in the bone marrow preferentially gave rise to Siglec-H- CD8α+ pre-cDC2As in tissues, which differentiated into T-bet+ cDC2As. In contrast, a Siglec-H- fraction of pre-cDCs in the bone marrow and periphery mostly generated T-bet- cDC2Bs, a lineage marked by the expression of LysM. Our results showed that cDC2A versus cDC2B fate specification starts in the bone marrow and suggest that cDC2 subsets are ontogenetically determined lineages, rather than cell states imposed by the peripheral tissue environment.

Secreted gelsolin inhibits DNGR-1-dependent cross-presentation and cancer immunity.

Cross-presentation of antigens from dead tumor cells by type 1 conventional dendritic cells (cDC1s) is thought to underlie priming of anti-cancer CD8+ T cells. cDC1 express high levels of DNGR-1 (a.k.a. CLEC9A), a receptor that binds to F-actin exposed by dead cell debris and promotes cross-presentation of associated antigens. Here, we show that secreted gelsolin (sGSN), an extracellular protein, decreases DNGR-1 binding to F-actin and cross-presentation of dead cell-associated antigens by cDC1s. Mice deficient in sGsn display increased DNGR-1-dependent resistance to transplantable tumors, especially ones expressing neoantigens associated with the actin cytoskeleton, and exhibit greater responsiveness to cancer immunotherapy. In human cancers, lower levels of intratumoral sGSN transcripts, as well as presence of mutations in proteins associated with the actin cytoskeleton, are associated with signatures of anti-cancer immunity and increased patient survival. Our results reveal a natural barrier to cross-presentation of cancer antigens that dampens anti-tumor CD8+ T cell responses.

Anti-Acanthamoeba metallopharmaceuticals: Amoebicidal activity and synergistic effect of copper(II) coordination compound.

Acanthamoeba spp. emerged as a clinically important pathogen related to amoebic keratitis. It is among the main causes of corneal transplantation and vision loss in ophthalmology. The treatment protocols have a low cure rate, high toxicity, and need for drug combination. Transition metal compounds have shown promising antiprotozoal effects. This study evaluates the amoebicidal activity of copper(II) coordination compounds in combination with chlorhexidine and the cytotoxicity to topical ocular application. These copper(II) coordination compounds were screened against Acanthamoeba castellanii trophozoites (ATCC 50492). The cytotoxicity on rabbit corneal cell line (ATCC-CCL 60) was performed. The compounds showed high amoebicidal potential, with inhibition of trophozoite viability above 80%. The Cp12 and Cp13 compounds showed Minimal Inhibitory Amoebicidal Concentration (MIAC) at 200 µM and mean inhibitory concentration (IC50) values lower than 10 µM. Against the cysts, Cp12 showed a reduction in viability (48%) in the longest incubation period. A synergistic effect for Cp12 with chlorhexidine was observed. The compounds have a dose-dependent effect against rabbit corneal cells. Compound Cp12 has potential for future application in developing ophthalmic formulations against Acanthamoeba keratitis and its use in multipurpose solutions is highlighted.

Psoriasis and steatotic liver disease: Are PNPLA3 and TM6SF2 polymorphisms suitable for the hepato-dermal axis hypothesis?

INTRODUCTION AND OBJECTIVES: A high prevalence of steatotic liver disease has been described in psoriasis. However, the influence of genetic polymorphisms has yet to be investigated in this scenario. This study aims to determine the frequency of steatosis, advanced liver fibrosis and PNPLA3/TM6SF2 genotypes in individuals with psoriasis and to evaluate the impact of genetic polymorphisms, metabolic parameters and cumulative methotrexate dose on steatosis and fibrosis. MATERIALS AND METHODS: Cross-sectional study that prospectively included psoriasis outpatients, submitted to clinical and laboratory analysis, transient elastography (FibroScan®, Fr) and PNPLA3/TM6SF2 genotyping. Steatosis was defined by CAP ≥275 dB/m and advanced liver fibrosis as transient elastography ≥10 kPa. Logistic regression analysis evaluated the independent variables related to steatosis and fibrosis; p-value< 0.05 was considered significant. RESULTS: One hundred and ninety-nine patients were enrolled (age 54.6 ± 12.6 years, 57.3% female). Metabolic syndrome (MetS), steatosis and advanced liver fibrosis prevalence were 55.8%, 54.8% and 9%, respectively. PNPLA3 and TM6SF2 genotypes frequencies were CC 42.3%/CG 49.5%/GG 8.2% and CC 88.7%/ CT 11.3%/ TT 0%. MetS (OR3.01 95%CI 1.51-5.98; p = 0.002) and body mass index (OR1.17 95%CI 1.08-1.26; p < 0.01) were independently associated with steatosis. Diabetes Mellitus (T2DM) (OR10.76 95%CI 2.42-47.87; p = 0.002) and harboring at least one PNPLA3 G allele (OR5.66 95%CI 1.08-29.52; p = 0.039) were associated with advanced fibrosis, but not TM6SF2 polymorphism or cumulative MTX dose. CONCLUSIONS: MetS and T2DM confer higher odds for steatosis and advanced fibrosis in individuals with psoriasis. PNPLA3 G allele, but not TM6SF2 polymorphism, impacts a 5-fold odds of advanced liver fibrosis.

Fertilization with follicular fluid reduces HSP70 and BAX expression on bovine in vitro embryos.

The in vivo fertilization process occurs in the presence of follicular fluid (FF). The aim of this study was to evaluate the effect of in vitro fertilization medium supplementation with 5% or 10% bovine follicular fluid (BFF) on the production of in vitro bovine embryos. FF was collected from ovarian follicles with a diameter of 8-10 mm, and cumulus-oocyte complexes (COCs) were co-incubated with sperm for 24 h in the commercial medium BotuFIV® (BotuPharma©), being distributed among the experimental groups: oocytes fertilized in a control medium; oocytes fertilized in a medium supplemented with 5% BFF; and oocytes fertilized in a medium supplemented with 10% BFF. After fertilization, the zygotes were cultured in vitro for 8 days. Embryo development was assessed through cleavage rates (day 2) and blastocyst formation rates (day 8). The relative expression of the genes OCT4, IFNT2, BAX, HSP70 and SOD2 was measured using the real-time polymerase chain reaction method. There was no difference (p > .05) among the different experimental groups in terms of cleavage rates and blastocyst formation rates. Regarding the gene expression results, only the blastocysts from oocytes fertilized with 10% BFF showed significantly lower expression of IFNT2 (p = .003) and SOD2 (p = .01) genes compared to blastocysts from oocytes fertilized in control medium alone, while there was no difference between blastocyst from oocytes fertilized in control medium and the ones from oocytes fertilized with 5% BFF. In addition to this, the blastocysts from oocytes fertilized with 5% BFF showed significantly reduced levels of expression of the heat shock protein HSP70 (p < .001) and the pro-apoptotic protein BAX (p = .015) compared to blastocysts from oocytes fertilized with control medium. This may indicate that lower supplementation of BFF to the IVF medium creates a more suitable environment for fertilization and is less stressful for the zygote.

Differentiation of glioblastoma stem cells promoted by miR-128 or miR-302a overexpression enhances senescence-associated cytotoxicity of axitinib.

Despite the intense global efforts towards an effective treatment of glioblastoma (GB), current therapeutic options are unsatisfactory with a median survival time of 12-15 months after diagnosis, which has not improved significantly over more than a decade. The high tumoral heterogeneity confers resistance to therapies, which has hindered a successful clinical outcome, GB remaining among the deadliest cancers. A hallmark of GB is its high recurrence rate, which has been attributed to the presence of a small subpopulation of tumor cells called GB stem-like cells (GSC). In the present work, the efficacy of a multimodal strategy combining microRNA (miRNA) modulation with new generation multitargeted tyrosine kinase inhibitors (imatinib and axitinib) was investigated aiming at tackling this subpopulation of GB cells. MiR-128 and miR-302a were selected as attractive therapeutic candidates on the basis of previous findings reporting that reestablishment of their decreased expression levels in GSC resulted in cell differentiation, which could represent a possible strategy to sensitize GSC to chemotherapy. Our results show that overexpression of miR-128 or miR-302a induced GSC differentiation, which enhanced senescence mediated by axitinib treatment, thus further impairing GSC proliferation. We also provided evidence for the capacity of GSC to efficiently internalize functionalized stable nucleic acid lipid particles, previously developed and successfully applied in our laboratory to target GB. Taken together, our findings will be important in the future design of a GB-targeted multimodal miRNA-based gene therapy, combining overexpression of miR-128 or miR-302a with axitinib treatment, endowed with the ability to overcome drug resistance.

Downregulation of long non-protein coding RNA MVIH impairs glioblastoma cell proliferation and invasion through an miR-302a-dependent mechanism.

Glioblastoma (GB) is the most frequent and malignant type of brain tumor, for which no effective therapy exists. The high proliferative and invasive nature of GB, as well as its acquired resistance to chemotherapy, makes this type of cancer extremely lethal shortly after diagnosis. Long non-protein coding RNAs (lncRNA) are a class of regulatory RNAs whose levels can be dysregulated in the context of diseases, unbalancing several physiological processes. The lncRNA associated with microvascular invasion in hepatocellular carcinoma (lncRNA-MVIH), overexpressed in several cancers, was described to co-precipitate with phosphoglycerate kinase 1 (PGK1), preventing secretion of this enzyme to the extracellular environment and promoting cell migration and invasion. We hypothesized that, by silencing the expression of lncRNA-MVIH, the secretion of PGK1 would increase, reducing GB cell migration and invasion capabilities. We observed that lncRNA-MVIH silencing in human GB cells significantly decreased glycolysis, cell growth, migration, and invasion and sensitized GB cells to cediranib. However, no increase in extracellular PGK1 was observed as a consequence of lncRNA-MVIH silencing, and therefore, we investigated the possibility of a mechanism of miRNA sponge of lncRNA-MVIH being in place. We found that the levels of miR-302a loaded onto RISC increased in GB cells after lncRNA-MVIH silencing, with the consequent downregulation of several miR-302a molecular targets. Our findings suggest a new mechanism of action of lncRNA-MVIH as a sponge of miR-302a. We suggest that lncRNA-MVIH knockdown may be a promising strategy to address GB invasiveness and chemoresistance, holding potential towards its future application in a clinical context.

MiR-200c-based metabolic modulation in glioblastoma cells as a strategy to overcome tumor chemoresistance.

Glioblastoma (GB) is the most aggressive and common form of primary brain tumor characterized by fast proliferation, high invasion and resistance to current standard treatment. The average survival rate post-diagnosis is 14.6 months, despite the aggressive standard post-surgery radiotherapy concomitant with chemotherapy with temozolomide (TMZ). Currently, efforts are being endowed to develop new and more efficient therapeutic approaches capable to overcome chemoresistance, inhibit tumor progression and improve overall patient survival rate. Abnormal microRNA (miRNA) expression has been correlated with chemoresistance, proliferation and resistance to apoptosis, which result from their master regulatory role of gene expression. Altered cell metabolism, favoring glycolysis, was identified as an emerging cancer hallmark and has been described in GB, thus offering a new target for innovative GB therapies. In this work, we hypothesized that a gene therapy-based strategy consisting of the overexpression of a miRNA downregulated in GB and predicted to target crucial metabolic enzymes might promote a shift of GB cell metabolism, decreasing the glycolytic dependence of tumor cells and contributing to their sensitization to chemotherapy with TMZ. The increase of miR-200c levels in DBTRG cells resulted in downregulation of messenger RNA of enzymes involved in bioenergetics pathways and impaired cell metabolism and mobility. In addition, miR-200c overexpression prior to DBTRG cell exposure to TMZ resulted in cell cycle arrest. Overall, our results show that miR-200c overexpression could offer a way to overcome chemoresistance developed by GB cells in response to current standard chemotherapy, providing an improvement to current GB standard treatment, with benefit for patient outcome.

Clonal variability in chromosomal instability as a potential driver in the acquisition of tumorigenic phenotype in chronic arsenic-exposed and hsa-miR-186 overexpressing human keratinocytes.

Chronic arsenic exposure through drinking water is a global health issue, affecting >200 million people. Arsenic is a group I human carcinogen and causes chromosomal instability (CIN). Arsenic exposure is the second most common cause of skin cancer after UV radiation. hsa-miR-186 is overexpressed in arsenic-induced squamous cell carcinoma relative to premalignant hyperkeratosis. Among predicted targets of hsa-miR-186 are cell cycle regulators including regulators of mitotic progression. Disruption of mitotic progression can contribute to CIN. Thus, we hypothesized that hsa-miR-186 overexpression contributes to malignant transformation of arsenic exposed HaCaT cells by induction of CIN. Stable clones of HaCaT cells transfected with pEP-hsa-miR-186 expression vector or empty vector were maintained under puromycin selection and exposed to 0 or 100 nM NaAsO2 and cultured for 29 weeks. HaCaT clones overexpressing hsa-miR-186 and exposed to NaAsO2 showed increased CIN and anchorage independent growth at 29 weeks in a stochastic manner, in contrast to unexposed empty vector transfected clones. These results suggest that clonal variability mediates arsenic-induced carcinogenesis in hsa-miR-186 overexpressing human keratinocytes.

Novel Foscan®-derived ring-fused chlorins for photodynamic therapy of cancer.

Photodynamic therapy (PDT) is an established anticancer treatment that combines the use of a photosensitiser (PS) and a light source of a specific wavelength for the generation of reactive oxygen species (ROS) that are toxic to the tumour cells. Foscan® (mTHPC) is a clinically-approved chlorin used for the PDT treatment of advanced head and neck, prostate and pancreatic cancers but is characterized by being photochemically unstable and associated with prolonged skin photosensitivity. Herein, we report the synthesis of new 4,5,6,7-tetrahydropyrazolo[1,5-a]pyridine-fused chlorins, having the meso-tetra(3-hydroxyphenyl)macrocycle core of mTHPC, by exploring the [8π + 2π] cycloaddition of a meso-tetra(3-hydroxyphenyl)porphyrin derivative with diazafulvenium methides. These chlorins have photochemical properties similar to Foscan® but are much more photostable. Among the novel compounds, two chlorins with a hydroxymethyl group and its azide derivative present in the 4,5,6,7-tetrahydropyrazolo[1,5-a]pyridine-fused system, are promising photodynamic agents with activity in the 100 nM range against triple-negative breast cancer cells and, in the case of azidomethyl chlorin, a safer phototherapeutic index compared to Foscan®.

Natural parasitism of the coffee leaf miner: climate factors, insecticide, and landscape affecting parasitoid diversity and their ecosystem services in coffee agroecosystems.

Climate factors, pesticides, and landscape in coffee agroecosystems directly affect the populations of the coffee leaf miner and its parasitoids. This study aimed to investigate the effects of climate factors, insecticide use, and landscape on natural parasitism, parasitoid diversity, and infestation of L. coffeella in coffee plantations in the Planalto region, Bahia, Brazil. Mined leaves were collected monthly in six coffee plantations with varying edge density, vegetation cover, landscape diversity in scales of 500 to 3000 m of radius, insecticide use, and climate factors. Closterocerus coffeellae, and Proacrias coffeae (Eulophidae) predominated in the pest's natural parasitism. Our record is the first for the occurrence of Stiropius reticulatus, Neochrysocharis sp. 1, Neochrysocharis sp. 2, and Zagrammosoma sp. in Bahia. Higher temperature and larger forest cover increased the coffee leaf miner infestation. Higher rainfall values, insecticide use, and landscape diversity decreased the pest infestations. Natural parasitism and species diversity are favoured by increase in temperature, forest cover, and edge density, while increase in rainfall, insecticide use, and landscape diversity lead them to decrease.The natural parasitism and diversity of parasitoid species of the coffee leaf miner have been enhancing in the areas with greater forest cover and edge density associated with low use of insecticides. The areas composed of different lands with annual croplands surrounding the coffee plantations showed less natural parasitism and parasitoid species diversity. The ecosystem services provided by C. coffeellae and P. coffeae in coffee crops areas require conservation and these species are potential bioproducts for applied biological control programmes.

miR-186 induces tetraploidy in arsenic exposed human keratinocytes.

Chronic inorganic arsenic (iAs) exposure in drinking water is a global issue affecting >225 million people. Skin is a major target organ for iAs. miRNA dysregulation and chromosomal instability (CIN) are proposed mechanisms of iAs-induced carcinogenesis. CIN is a cancer hallmark and tetraploid cells can better tolerate increase in chromosome number and aberration, contributing to the evolution of CIN. miR-186 is overexpressed in iAs-induced squamous cell carcinoma relative to iAs-induced hyperkeratosis. Bioinformatic analysis indicated that miR-186 targets mRNAs of important cell cycle regulators including mitotic checkpoint serine/threonine kinase B (BUB1) and cell division cycle 27 (CDC27). We hypothesized that miR-186 overexpression contributes to iAs-induced transformation of keratinocytes by targeting mitotic regulators leading to induction of CIN. Ker-CT cells, a near diploid human keratinocyte cell line, were transduced with miR-186 overexpressing or scrambled control lentivirus. Stable clones were isolated after puromycin selection. Clones transduced with lentivirus expressing either a scrambled control miRNA or miR-186 were maintained with 0 or 100 nM iAs for 4 weeks. Unexposed scrambled control clones were considered as passage matched controls. Chronic iAs exposure increased miR-186 expression in miR-186 clones. miR-186 overexpression significantly reduced CDC27 levels irrespective of iAs exposure. The percentage of tetraploid or aneuploid cells was increased in iAs exposed miR-186 clones. Aneuploidy can arise from a tetraploid intermediate. Suppression of CDC27 by miR-186 may lead to impairment of mitotic checkpoint complex formation and its ability to maintain cell cycle arrest leading to chromosome misalignment. As a result, cells overexpressing miR-186 and chronically exposed to iAs may have incorrect chromosome segregation and CIN. These data suggest that dysregulation of miRNA by iAs mediates tetraploidy, aneuploidy and chromosomal instability contributing to iAs-induced carcinogenesis.

C-reactive protein-to-albumin ratio and six-month mortality in incident hemodialysis patients.

BACKGROUND: The first few months of hemodialysis (HD) are associated with a higher risk of mortality. Protein-energy malnutrition is a demonstrated major risk factor for mortality in this population. The C-Reactive Protein to Albumin ratio (CAR) has also been associated with increased mortality risk. The aim of this study was to determine the predictive value of CAR for six-month mortality in incident HD patients. METHODS: Retrospective analysis of incident HD patients between January 2014 and December 2019. CAR was calculated at the start of HD. We analyzed six-month mortality. A Cox regression was performed to predict six-month mortality and the discriminatory ability of CAR was determined using the receiver operating characteristic (ROC) curve. RESULTS: A total of 787 patients were analyzed (mean age 68.34 ± 15.5 years and 60.6% male). The 6-month mortality was 13.8% (n = 109). Patients who died were significantly older (p < 0.001), had more cardiovascular disease (p = 0.010), had central venous catheter at the start of HD (p < 0.001), lower parathyroid hormone (PTH) level (p = 0.014) and higher CAR (p = 0.015). The AUC for mortality prediction was 0.706 (95% CI (0.65-0.76), p < 0.001). The optimal CAR cutoff was ≥0.5, HR 5.36 (95% CI 3.21-8.96, p < 0.001). CONCLUSION: We demonstrated that higher CAR was significantly associated with a higher mortality risk in the first six months of HD, highlighting the prognostic importance of malnutrition and inflammation in patients starting chronic HD.

STEAP1 Knockdown Decreases the Sensitivity of Prostate Cancer Cells to Paclitaxel, Docetaxel and Cabazitaxel.

The Six Transmembrane Epithelial Antigen of the Prostate 1 (STEAP1) protein has been indicated as an overexpressed oncoprotein in prostate cancer (PCa), associated with tumor progression and aggressiveness. Taxane-based antineoplastic drugs such as paclitaxel, docetaxel, or cabazitaxel, have been investigated in PCa treatment, namely for the development of combined therapies with the improvement of therapeutic effectiveness. This study aimed to evaluate the expression of STEAP1 in response to taxane-based drugs and assess whether the sensitivity of PCa cells to treatment with paclitaxel, docetaxel, or cabazitaxel may change when the STEAP1 gene is silenced. Thus, wild-type and STEAP1 knockdown LNCaP and C4-2B cells were exposed to paclitaxel, docetaxel or cabazitaxel, and STEAP1 expression, cell viability, and survival pathways were evaluated. The results obtained showed that STEAP1 knockdown or taxane-based drugs treatment significantly reduced the viability and survival of PCa cells. Relatively to the expression of proliferation markers and apoptosis regulators, LNCaP cells showed a reduced proliferation, whereas apoptosis was increased. However, the effect of paclitaxel, docetaxel, or cabazitaxel treatment was reversed when combined with STEAP1 knockdown. Besides, these chemotherapeutic drugs may stimulate the cell growth of PCa cells knocked down for STEAP1. In conclusion, this study demonstrated that STEAP1 expression levels might influence the response of PCa cells to chemotherapeutics drugs, indicating that the use of paclitaxel, docetaxel, or cabazitaxel may lead to harmful effects in PCa cells with decreased expression of STEAP1.

A Novel Genetic Variant in MBD5 Associated with Severe Epilepsy and Intellectual Disability: Potential Implications on Neural Primary Cilia.

Disruptions in the MBD5 gene have been linked with an array of clinical features such as global developmental delay, intellectual disability, autistic-like symptoms, and seizures, through unclear mechanisms. MBD5 haploinsufficiency has been associated with the disruption of primary cilium-related processes during early cortical development, and this has been reported in many neurodevelopmental disorders. In this study, we describe the clinical history of a 12-year-old child harboring a novel MBD5 rare variant and presenting psychomotor delay and seizures. To investigate the impact of MBD5 haploinsufficiency on neural primary cilia, we established a novel patient-derived cell line and used CRISPR-Cas9 technology to create an isogenic control. The patient-derived neural progenitor cells revealed a decrease in the length of primary cilia and in the total number of ciliated cells. This study paves the way to understanding the impact of MBD5 haploinsufficiency in brain development through its potential impact on neural primary cilia.

Meaning of Life Therapy: A Pilot Study of a Novel Psycho-Existential Intervention for Palliative Care in Cancer.

Intervention in Palliative Care aims to provide physical, psychosocial, and spiritual relief for patients and family members. Brief interventions with a psycho-existential approach have shown positive responses; however, cultural adaptations are needed. This pilot study aimed to develop the Meaning of Life Therapy (MLT), a novel psycho-existential intervention, rooted in the Dignity Therapy, Life Review, and Meaning-Centered Psychotherapy. MLT was culturally adapted to the Portuguese context to include questions about forgiveness, apology, reconciliation, farewell, and a legacy document, i.e., the Life Letter. Nine PC cancer patients answered a 14-question MLT protocol, intended to help patients find purpose and meaning in life. Eight themes emerged: Family, Preservation of Identity, Life Retrospective, Clinical Situation, Achievements, Socio-Professional Valorization, Forgiveness/Apology/Reconciliation, and Saying Goodbye. MLT has proved its ability to respond to the psycho-existential needs of PC patients. Further studies should be conducted to gain extensive knowledge of the effectiveness of culturally responsive interventions.

miRNA dysregulation is an emerging modulator of genomic instability.

Genomic instability consists of a range of genetic alterations within the genome that contributes to tumor heterogeneity and drug resistance. It is a well-established characteristic of most cancer cells. Genome instability induction results from defects in DNA damage surveillance mechanisms, mitotic checkpoints and DNA repair machinery. Accumulation of genetic alterations ultimately sets cells towards malignant transformation. Recent studies suggest that miRNAs are key players in mediating genome instability. miRNAs are a class of small RNAs expressed in most somatic tissues and are part of the epigenome. Importantly, in many cancers, miRNA expression is dysregulated. Consequently, this review examines the role of miRNA dysregulation as a causal step for induction of genome instability and subsequent carcinogenesis. We focus specifically on mechanistic studies assessing miRNA(s) and specific subtypes of genome instability or known modes of genome instability. In addition, we provide insight on the existing knowledge gaps within the field and possible ways to address them.

Microglia-dependent remodeling of neuronal circuits.

Microglia are tissue-resident macrophages responsible for the surveillance, neuronal support, and immune defense of the brain parenchyma. Recently, the role played by microglia in the formation and function of neuronal circuits has garnered substantial attention. During development, microglia have been shown to engulf neuronal precursors and participate in pruning mechanisms while, in the mature brain, they influence synaptic signaling, provide trophic support and shape synaptic plasticity. Recently, studies have unveiled different microglial characteristics associated with specific brain regions. This emerging view suggests that the maturation and function of distinct neuronal circuits may be potentially associated with the molecular identity microglia adopts across the brain. Here, we review and summarize the known role of these cells in the thalamus, hippocampus, cortex, and cerebellum. We focus on in vivo studies to highlight the characteristics of microglia that may be important in the remodeling of these neuronal circuits and in relation to neurodevelopmental and neuropsychiatric disorders.

Chronic arsenic exposure suppresses ATM pathway activation in human keratinocytes.

An estimated 220 million people worldwide are chronically exposed to inorganic arsenic (iAs) primarily as a result of drinking iAs-contaminated water. Chronic iAs exposure is associated with a plethora of human diseases including skin lesions and multi-organ cancers. iAs is a known clastogen, inducing DNA double strand breaks (DSBs) in both exposed human populations and in vitro. However, iAs does not directly interact with DNA, suggesting that other mechanisms, such as inhibition of DNA repair and DNA Damage Response (DDR) signaling, may be responsible for iAs-induced clastogenesis. Recent RNA-sequencing data from human keratinocytes (HaCaT cells) indicate that mRNAs for phosphatases important for resolution of DDR signaling are induced as a result of chronic iAs exposure prior to epithelial to mesenchymal transition. Here, we report that phosphorylation of ataxia telengectasia mutated (ATM) protein at a critical site (pSer1981) important for DDR signaling, and downstream CHEK2 activation, are significantly reduced in two human keratinocyte lines as a result of chronic iAs exposure. Moreover, RAD50 expression is reduced in both of these lines, suggesting that suppression of the MRE11-RAD50-NBS1 (MRN) complex may be responsible for reduced ATM activation. Lastly, we demonstrate that DNA double strand break accumulation and DNA damage is significantly higher in human keratinocytes with low dose iAs exposure. Thus, inhibition of the MRN complex in iAs-exposed cells may be responsible for reduced ATM activation and reduced DSB repair by homologous recombination (HR). As a result, cells may favor error-prone DSB repair pathways to fix damaged DNA, predisposing them to chromosomal instability (CIN) and eventual carcinogenesis often seen resulting from chronic iAs exposure.