Authors: Harris ML, Fufa TD, Palmer JW, Joshi SS, Larson DM, Incao A, Gildea DE, Trivedi NS, Lee AN, Day CP, Michael HT, Hornyak TJ, Merlino G; NISC Comparative Sequencing Program, Pavan WJ
Journal: PLoS Biol. 2018 May 3;16(5):e2003648. doi: 10.1371/journal.pbio.2003648. eCollection 2018 May.
Melanocyte stem cells (McSCs) and mouse models of hair graying serve as useful systems to uncover mechanisms involved in stem cell self-renewal and the maintenance of regenerating tissues. Interested in assessing genetic variants that influence McSC maintenance, we found previously that heterozygosity for the melanogenesis associated transcription factor, Mitf, exacerbates McSC differentiation and hair grayingin mice that are predisposed for this phenotype. Based on transcriptome and molecular analyses of Mitfmi-vga9/+ mice, we report a novel role for MITF in the regulation of systemic innate immune gene expression. We also demonstrate that the viral mimic poly(I:C) is sufficient to expose genetic susceptibility to hair graying. These observations point to a critical suppressor of innate immunity, the consequences of innateimmune dysregulation on pigmentation, both of which may have implications in the autoimmune, depigmenting disease, vitiligo.
Authors: Naz S, Sowers AL, Choudhuri R, Wissler MF, Gamson J, Mathias A, Cook JA, Mitchell JB
Journal: Clin Cancer Res. 2018 May 1. pii: clincanres.3575.2017. doi: 10.1158/1078-0432.CCR-17-3575. [Epub ahead of print]
PURPOSE: To characterize the ionizing radiation (IR) enhancing effects and underlying mechanisms of CDK4/6 inhibitor, Abemaciclib in Non-Small Cell Lung Cancer cells (NSCLC) in vitro and in vivo.
Experimental Design: IR enhancement by Abemaciclib in a variety of NSCLC cell lines was assessed by in vitro clonogenic assay, flow cytometry, and target inhibition verified by immunoblotting. IR-induced DNA damage repair was evaluated by γ-H2AX analysis. Global metabolic alterations by Abemaciclib and IR combination was evaluated by LC/MS mass spectrometry and YSI-Bioanalyzer. Effects of Abemaciclib and IR combination in vivo was studied by xenograft tumor regrowth delay, xenograft lysate immunoblotting, and tissue section immunohistochemistry.
RESULTS: Abemaciclib enhanced the radiosensitivity of NSCLC cells independent of RAS or EGFR status. Enhancement of radiosensitivity was lost in cell lines deficient for functional p53 and RB protein. Post-IR, Abemaciclib treatment inhibited DNA damage repair as measured by γ-H2AX. Mechanistically, Abemaciclib inhibited RB phosphorylation leading to cell cycle arrest. It also inhibited mTOR signaling and reduced intracellular amino acid pool causing nutrient stress. In vivo, Abemaciclib when administered in an adjuvant setting for the second week post-fractionated IR further inhibited vasculogenesis and tumor re-growth with sustained inhibition of RB/E2F activity, mTOR pathway, and HIF-1 expression. In summary, our study signifies inhibiting CDK4/6 pathway by Abemaciclib in combination with IR as a promising therapeutic strategy to treat NSCLC.
CONCLUSIONS: Abemaciclib in combination with IR enhances NSCLC radiosensitivity in preclinical models, potentially providing a novel biomarker driven combination therapeutic strategy for patients with NSCLC.
Authors: Freeman DW, Hooten NN, Eitan E, Green J, Mode NA, Bodogai M, Zhang Y, Lehrmann E, Zonderman AB, Biragyn A, Egan J, Becker KG, Mattson MP, Ejiogu N1, Evans MK
Journal: Diabetes. 2018 May 2. pii: db171308. doi: 10.2337/db17-1308. [Epub ahead of print]
Type 2 diabetes mellitus is a chronic age-associated degenerative metabolic disease that reflects relative insulin deficiency and resistance. Extracellular vesicles (EVs; exosomes, microvesicles and apoptotic bodies) are small (50-400 nM) lipid-bound vesicles capable of shuttling functional proteins, nucleic acids, and lipids as part of intercellular communication systems. Recent studies in mouse models and in cell culture suggest that EVs may modulate insulin signaling. Here, we designed cross-sectional and longitudinal cohorts of euglycemic, pre-diabetic and diabetic participants. Diabetic individuals had significantly higher levels of EVs in their circulation than euglycemic controls. Using a cell-specific EV assay, we identified that erythrocyte-derived EVs are higher with diabetes. We found that insulin resistance increases EV secretion. Furthermore, the levels insulin signaling proteins were altered in EVs from individuals with high levels of insulin resistance and β-cell dysfunction. Moreover, EVs from diabetic individuals were preferentially internalized by circulating leukocytes. Cytokine levels in the media and in EVs were higher from monocytes incubated with diabetic EVs. Microarray of these leukocytes revealed altered gene expression pathways related to cell survival, oxidative stress and immune function. Collectively, these results suggest that insulin resistance increases the secretion of EVs, which are preferentially internalized by leukocytes and alters leukocyte function.
Authors: Doumatey AP, He WJ, Gaye A, Lei L, Zhou J, Gibbons GH, Adeyemo A, Rotimi CN
Journal: Sci Rep. 2018 May 16;8(1):7680. doi: 10.1038/s41598-018-26065-5.
Obese individuals without expected metabolic co-morbidities are referred to as metabolically healthy obese (MHO). The molecular mechanisms underlying this phenotype remain elusive. MicroRNAs may be involved in the MHO phenotype. To test this hypothesis, we screened 179 serum miRNAs in 20 African-American women (10 MHOs and 10 metabolically abnormal obese individuals -MAO). We identified 8 differentially expressed miRNAs (DEMs) with validation in an independent sample of 64 MHO and 34 MAO. Of the eight DEMs in the screening phase (p ≤ 0.05), miR-374a-5p remained significant (p = 0.04) with directional consistency in the validation sample. Ingenuity Pathway analysis revealed that miR-374a-5p putatively targeted 37 mRNAs (e.g. chemokines and transcription factors) which are members of canonical pathways involved in inflammation (IL-17A signaling) and lipid metabolism. Analysis restricted to adipocytes, the main source of circulating miRNAs in obesity, identified 3 mRNAs (CCL2, STEAP2, EN1) as the main target of miR-374a-5p. Evaluation of the 3 mRNAs in an independent sample showed that CCL2 was significantly downregulated (p = 0.0005). In summary, MiR-374a-5p is upregulated in MHO compared to MAO individuals and appears to show association with downregulation of pro-inflammatory markers that are linked to insulin resistance. Given the correlative nature of our findings, functional studies are needed.
Authors: Solis E Jr, Cameron-Burr KT, Shaham Y, Kiyatkin EA
Journal: Neuropsychopharmacology. 2018 Mar;43(4):810-819. doi: 10.1038/npp.2017.181. Epub 2017 Aug 29.
Fentanyl is a potent synthetic opioid used extensively in humans for general anesthesia and analgesia. Fentanyl has emerged as a recreational drug, often in combination with heroin, and can result in lethality during overdose. Fentanyl is well characterized as an anesthetic, but the basic physiological effects of fentanyl in the brain when taken as a drug of abuse are largely unknown. We used high-speed amperometry in freely moving rats to examine the effects of intravenous fentanyl at doses within the range of possible human intake (3-40 μg/kg) on oxygen and glucose levels in nucleus accumbens (NAc). Fentanyl induced a rapid, dose-dependent decrease in NAc oxygen followed by a more delayed and prolonged increase in NAc glucose. Fentanyl induced similar oxygen decreases in the basolateral amygdala, indicating that brain hypoxia could be a generalized phenomenon. We used oxygen recordings in the subcutaneous space to confirm that fentanyl-induced brain hypoxia results from decreases in blood oxygen levels caused by drug-induced respiratory depression. Temperature recordings in the NAc, muscle, and skin showed that fentanyl induces biphasic changes in brain temperature, with an initial decrease that results primarily from peripheral vasodilation, and a subsequent increase driven by metabolic brain activation. The initial vasodilation appears caused by respiratory depression-induced hypoxia and a subsequent rise in CO2 that drives fentanyl-induced increases in NAc glucose. Together, these data suggest that fentanyl-induced respiratory depression triggers brain hypoxia and subsequent hyperglycemia, both of which precede slower changes in brain temperature and metabolic brain activity.
Authors: Kijima T, Prince TL, Tigue ML, Yim KH, Schwartz H, Beebe K, Lee S, Budzynski MA, Williams H, Trepel JB, Sistonen L, Calderwood S, Neckers L
Journal: Sci Rep. 2018 May 3;8(1):6976. doi: 10.1038/s41598-018-25404-w.
Heat shock factor 1 (HSF1) initiates a broad transcriptional response to proteotoxic stress while also mediating a cancer-specific transcriptional program. HSF1 is thought to be regulated by molecular chaperones, including Heat Shock Protein 90 (HSP90). HSP90 is proposed to sequester HSF1 in unstressed cells, but visualization of this interaction in vivo requires protein crosslinking. In this report, we show that HSP90 binding to HSF1 depends on HSP90 conformation and is only readily visualized for the ATP-dependent, N-domain dimerized chaperone, a conformation only rarely sampled by mammalian HSP90. We have used this mutationally fixed conformation to map HSP90 binding sites on HSF1. Further, we show that ATP-competitive, N-domain targeted HSP90 inhibitors disrupt this interaction, resulting in the increased duration of HSF1 occupancy of the hsp70 promoter and significant prolongation of both the constitutive and heat-induced HSF1 transcriptional activity. While our data do not support a role for HSP90 in sequestering HSF1 monomers to suppress HSF1 transcriptional activity, our findings do identify a noncanonical role for HSP90 in providing dynamic modulation of HSF1 activity by participating in removal of HSF1 trimers from heat shock elements in DNA, thus terminating the heat shock response.
Authors: Pearson CS, Mencio CP, Barber AC, Martin KR, Geller HM
Journal: Elife. 2018 May 15;7. pii: e37139. doi: 10.7554/eLife.37139. [Epub ahead of print]
The failure of mammalian CNS neurons to regenerate their axons derives from a combination of intrinsic deficits and extrinsic factors. Following injury, chondroitin sulfate proteoglycans (CSPGs) within the glial scar inhibit axonal regeneration, an action mediated by the sulfated glycosaminoglycan (GAG) chains of CSPGs, especially those with 4-sulfated (4S) sugars. Arylsulfatase B (ARSB) selectively cleaves 4S groups from the non-reducing ends of GAG chains without disrupting other, growth-permissive motifs. We demonstrate that ARSB is effective in reducing the inhibitory actions of CSPGs both in in vitro models of the glial scar and after optic nerve crush (ONC) in adult mice. ARSB is clinically approved for replacement therapy in patients with mucopolysaccharidosis VI and therefore represents an attractive candidate for translation to the human CNS.
Authors: Martin-Martin I, Chagas AC, Guimaraes-Costa AB, Amo L, Oliveira F, Moore IN, DeSouza-Vieira TS, Sanchez EE, Suntravat M, Valenzuela JG, Ribeiro JMC, Calvo E
Journal: PLoS Pathog. 2018 May 3;14(5):e1007006. doi: 10.1371/journal.ppat.1007006. [Epub ahead of print]
Salivary components from disease vectors help arthropods to acquire blood and have been shown to enhance pathogen transmission in different model systems. Here we show that two salivary enzymes from Lutzomyia longipalpis have a synergist effect that facilitates a more efficient blood meal intake and diffusion of other sialome components. We have previously shown that Lundep, a highly active endonuclease, enhances parasite infection and prevent blood clotting by inhibiting the intrinsic pathway of coagulation. To investigate the physiological role of a salivary hyaluronidase in blood feeding we cloned and expressed a recombinant hyaluronidase from Lu. longipalpis. Recombinant hyaluronidase (LuloHya) was expressed in mammalian cells and biochemically characterized in vitro. Our study showed that expression of neutrophil CXC chemokines and colony stimulating factors were upregulated in HMVEC cells after incubation with LuloHya and Lundep. These results were confirmed by the acute hemorrhage, edema and inflammation in a dermal necrosis (dermonecrotic) assay involving a massive infiltration of leukocytes, especially neutrophils, in mice co-injected with hemorrhagic factor and these two salivary proteins. Moreover, flow cytometry results showed that LuloHya and Lundep promote neutrophil recruitment to the bite site that may serve as a vehicle for establishment of Leishmania infection. A vaccination experiment demonstrated that LuloHya and Lundep confer protective immunity against cutaneous leishmaniasis using the Lu. longipalpis-Leishmania major combination as a model. Animals (C57BL/6) immunized with LuloHya or Lundep showed minimal skin damage while lesions in control animals remained ulcerated. This protective immunity was abrogated when B-cell-deficient mice were used indicating that antibodies against both proteins play a significant role for disease protection. Rabbit-raised anti-LuloHya antibodies completely abrogated hyaluronidase activity in vitro. Moreover, in vivo experiments demonstrated that blocking LuloHya with specific antibodies interferes with sand fly blood feeding. This work highlights the relevance of vector salivary components in blood feeding and parasite transmission and further suggests the inclusion of these salivary proteins as components for an anti-Leishmania vaccine.
Authors: Katki HA, Kovalchik SA, Petito LC, Cheung LC, Jacobs E, Jemal A, Berg C, Chaturvedi AK
Journal: Ann Intern Med. 2018 May 15. doi: 10.7326/M17-2701. [Epub ahead of print]
Background: Lung cancer screening guidelines recommend using individualized risk models to refer ever-smokers for screening. However, different models select different screening populations. The performance of each model in selecting ever-smokers for screening is unknown.
Objective: To compare the U.S. screening populations selected by 9 lung cancer risk models (the Bach model; the Spitz model; the Liverpool Lung Project [LLP] model; the LLP Incidence Risk Model [LLPi]; the Hoggart model; the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial Model 2012 [PLCOM2012]; the Pittsburgh Predictor; the Lung Cancer Risk Assessment Tool [LCRAT]; and the Lung Cancer Death Risk Assessment Tool [LCDRAT]) and to examine their predictive performance in 2 cohorts.
Design: Population-based prospective studies.
Setting: United States.
Participants: Models selected U.S. screening populations by using data from the National Health Interview Survey from 2010 to 2012. Model performance was evaluated using data from 337 388 ever-smokers in the National Institutes of Health–AARP Diet and Health Study and 72 338 ever-smokers in the CPS-II (Cancer Prevention Study II) Nutrition Survey cohort.
Measurements: Model calibration (ratio of model-predicted to observed cases [expected–observed ratio]) and discrimination (area under the curve [AUC]).
Results: At a 5-year risk threshold of 2.0%, the models chose U.S. screening populations ranging from 7.6 million to 26 million ever-smokers. These disagreements occurred because, in both validation cohorts, 4 models (the Bach model, PLCOM2012, LCRAT, and LCDRAT) were well-calibrated (expected–observed ratio range, 0.92 to 1.12) and had higher AUCs (range, 0.75 to 0.79) than 5 models that generally overestimated risk (expected–observed ratio range, 0.83 to 3.69) and had lower AUCs (range, 0.62 to 0.75). The 4 best-performing models also had the highest sensitivity at a fixed specificity (and vice versa) and similar discrimination at a fixed risk threshold. These models showed better agreement on size of the screening population (7.6 million to 10.9 million) and achieved consensus on 73% of persons chosen.
Limitation: No consensus on risk thresholds for screening.
Conclusion: The 9 lung cancer risk models chose widely differing U.S. screening populations. However, 4 models (the Bach model, PLCOM2012, LCRAT, and LCDRAT) most accurately predicted risk and performed best in selecting ever-smokers for screening.
Authors: Amita H, Kim HF, Smith M, Gopal A, Hikosaka O
Journal: Eur J Neurosci. 2018 May 8. doi: 10.1111/ejn.13936. [Epub ahead of print]
Direct and indirect pathways in the basal ganglia work together for controlling behavior. However, it is still a controversial topic whether these pathways are segregated or merged with each other. To address this issue, we studied the connections of these two pathways in the caudal parts of the basal ganglia of rhesus monkeys using anatomical tracers. Our previous studies showed that the caudal basal ganglia control saccades by conveying long-term values (stable values) of many visual objects toward the superior colliculus. In experiment 1, we injected a tracer in the caudate tail (CDt), and found local dense plexuses of axon terminals in the caudal-dorsal-lateral part of substantia nigra pars reticulata (cdlSNr) and the caudal-ventral part of globus pallidus externus (cvGPe). These anterograde projections may correspond to the direct and indirect pathways, respectively. To verify this in experiment 2, we injected different tracers into cdlSNr and cvGPe, and found many retrogradely labeled neurons in CDt and, in addition, the caudal-ventral part of the putamen (cvPut). These cdlSNr-projecting and cvGPe-projecting neurons were found intermingled in both CDt and cvPut (which we call 'striatum tail'). A small but significant proportion of neurons (< 15%) were double-labeled, indicating that they projected to both cdlSNr and cvGPe. These anatomical results suggest that stable value signals (good vs. bad) are sent from the striatum tail to cdlSNr and cvGPe in a biased (but not exclusive) manner. These connections may play an important role in biasing saccades toward higher-valued objects and away from lower-valued objects.