Browsing by Subject "MECHANISMS"

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  • Villaseñor-Altamirano, Ana B.; Watson, John D.; Prokopec, Stephenie D.; Yao, Cindy Q.; Boutros, Paul C.; Pohjanvirta, Raimo; Valdés-Flores, Jesús; Elizondo, Guillermo (2019)
    Alternative splicing is a co-transcriptional mechanism that generates protein diversity by including or excluding exons in different combinations, thereby expanding the diversity of protein isoforms of a single gene. Abnormalities in this process can result in deleterious effects to human health, and several xenobiotics are known to interfere with splicing regulation through multiple mechanisms. These changes could lead to human diseases such as cancer, neurological disorders, autoimmune diseases, and developmental disorders. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is an environmental contaminant generated as a byproduct of various industrial activities. Exposure to this dioxin has been linked to a wide range of pathologies through the alteration of multiple cellular processes. However, the effects of TCDD exposure on alternative splicing have not yet been studied. Here, we investigated whether a single po. dose of 5 μg/kg or 500 μg/kg TCDD influence hepatic alternative splicing in adult male C57BL/6Kou mouse. We identified several genes whose alternative splicing of precursor messenger RNAs was modified following TCDD exposure. In particular, we demonstrated that alternative splicing of Cyp1a1, Ahrr, and Actn1 was significantly altered after TCDD treatment. These findings show that the exposure to TCDD has an impact on alternative-splicing, and suggest a new avenue for understanding TCDD-mediated toxicity and pathogenesis.
  • Lai, Jeffrey K. F.; Sam, I-Ching; Verlhac, Pauline; Baguet, Joel; Eskelinen, Eeva-Liisa; Faure, Mathias; Chan, Yoke Fun (2017)
    Viruses have evolved unique strategies to evade or subvert autophagy machinery. Enterovirus A71 (EV-A71) induces autophagy during infection in vitro and in vivo. In this study, we report that EV-A71 triggers autolysosome formation during infection in human rhabdomyosarcoma (RD) cells to facilitate its replication. Blocking autophagosome-lysosome fusion with chloroquine inhibited virus RNA replication, resulting in lower viral titres, viral RNA copies and viral proteins. Overexpression of the non-structural protein 2BC of EV-A71 induced autolysosome formation. Yeast 2-hybrid and co-affinity purification assays showed that 2BC physically and specifically interacted with a N-ethylmaleimide-sensitive factor attachment receptor (SNARE) protein, syntaxin-17 (STX17). Co-immunoprecipitation assay further showed that 2BC binds to SNARE proteins, STX17 and synaptosome associated protein 29 (SNAP29). Transient knockdown of STX17, SNAP29, and microtubule-associated protein 1 light chain 3B (LC3B), crucial proteins in the fusion between autophagosomes and lysosomes) as well as the lysosomal-associated membrane protein 1 (LAMP1) impaired production of infectious EV-A71 in RD cells. Collectively, these results demonstrate that the generation of autolysosomes triggered by the 2BC non-structural protein is important for EV-A71 replication, revealing a potential molecular pathway targeted by the virus to exploit autophagy. This study opens the possibility for the development of novel antivirals that specifically target 2BC to inhibit formation of autolysosomes during EV-A71 infection.
  • Tuohinen, Suvi Sirkku; Skyttä, Tanja; Huhtala, Heini; Poutanen, Tuija; Virtanen, Vesa; Kellokumpu-Lehtinen, Pirkko-Liisa; Raatikainen, Pekka (2021)
    BACKGROUND Radiation therapy (RT) results in myocardial changes consisting of diffuse fibrosis, which may result in changes in diastolic function. OBJECTIVES The aim of this study was to explore RT-associated changes in left ventricular (LV) diastolic function. METHODS Sixty chemotherapy-naive patients with left-sided, early-stage breast cancer were studied with speckle tracking echocardiography at 3 time points: prior to, immediately after, and 3 years after RT. Global and regional early diastolic strain rate (SRe) were quantified, as were parameters of systolic function. RESULTS Regional changes in SRe, particularly the apical and anteroseptat segments, were observed over time and were more evident than global changes. The apical SRe declined from a median of 1.24 (interquartile range: 1.01 to 1.39) s(-1) at baseline to 1.02 (interquartile range: 0.79 to 1.15) s(-1) at 3 years of follow-up (p < 0.001). This decline was associated with the left ventricular maximal radiation dose (beta = 0.36, p = 0.007). The global SRe was CONCLUSIONS RT resulted in changes in the SRe in the apical and anteroseptat segments over 3 years of follow-up. Changes in SRe apical segments were present even in patients with preserved systolic function and were independently associated with RT dose and cardiovascular comorbidities. (C) 2021 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation.
  • Aspelund, Aleksanteri; Antila, Salli; Proulx, Steven T.; Karlsen, Tine Veronica; Karaman, Sinem; Detmar, Michael; Wiig, Helge; Alitalo, Kari (2015)
    The central nervous system (CNS) is considered an organ devoid of lymphatic vasculature. Yet, part of the cerebrospinal fluid (CSF) drains into the cervical lymph nodes (LNs). The mechanism of CSF entry into the LNs has been unclear. Here we report the surprising finding of a lymphatic vessel network in the dura mater of the mouse brain. We show that dural lymphatic vessels absorb CSF from the adjacent subarachnoid space and brain interstitial fluid (ISF) via the glymphatic system. Dural lymphatic vessels transport fluid into deep cervical LNs (dcLNs) via foramina at the base of the skull. In a transgenic mouse model expressing a VEGF-C/D trap and displaying complete aplasia of the dural lymphatic vessels, macromolecule clearance from the brain was attenuated and transport from the subarachnoid space into dcLNs was abrogated. Surprisingly, brain ISF pressure and water content were unaffected. Overall, these findings indicate that the mechanism of CSF flow into the dcLNs is directly via an adjacent dural lymphatic network, which may be important for the clearance of macromolecules from the brain. Importantly, these results call for a reexamination of the role of the lymphatic system in CNS physiology and disease.
  • Fountain, Toby; Ravinet, Mark; Naylor, Richard; Reinhardt, Klaus; Butlin, Roger K. (2016)
    The rapid evolution of insecticide resistance remains one of the biggest challenges in the control of medically and economically important pests. Insects have evolved a diverse range of mechanisms to reduce the efficacy of the commonly used classes of insecticides, and finding the genetic basis of resistance is a major aid to management. In a previously unstudied population, we performed an F-2 resistance mapping cross for the common bed bug, Cimex lectularius, for which insecticide resistance is increasingly widespread. Using 334 SNP markers obtained through RAD-sequencing, we constructed the first linkage map for the species, consisting of 14 putative linkage groups (LG), with a length of 407 cM and an average marker spacing of 1.3 cM. The linkage map was used to reassemble the recently published reference genome, facilitating refinement and validation of the current genome assembly. We detected a major QTL on LG12 associated with insecticide resistance, occurring in close proximity (1.2 Mb) to a carboxylesterase encoding candidate gene for pyrethroid resistance. This provides another example of this candidate gene playing a major role in determining survival in a bed bug population following pesticide resistance evolution. The recent availability of the bed bug genome, complete with a full list of potential candidate genes related to insecticide resistance, in addition to the linkage map generated here, provides an excellent resource for future research on the development and spread of insecticide resistance in this resurging pest species.
  • Raerinne, Jani (2018)
    In addition to their core explanatory and predictive assumptions, scientific models include simplifying assumptions, which function as idealizations, approximations, and abstractions. There are methods to investigate whether simplifying assumptions bias the results of models, such as robustness analyses. However, the equally important issue - the focus of this paper - has received less attention, namely, what are the methodological and epistemic strengths and limitations associated with different simplifying assumptions. I concentrate on one type of simplifying assumption, the use of mega parameters as abstractions in ecological models. First, I argue that there are two kinds of mega parameters qua abstractions, sufficient parameters and aggregative parameters, which have gone unnoticed in the literature. The two are associated with different heuristics, holism and reductionism, which many view as incompatible. Second, I will provide a different analysis of abstractions and the associated heuristics than previous authors. Reductionism and holism and the accompanying abstractions have different methodological and epistemic functions, strengths, and limitations, and the heuristics should be viewed as providing complementary research perspectives of cognitively limited beings. This is then, third, used as a premise to argue for epistemic and methodological pluralism in theoretical ecology. Finally, the presented taxonomy of abstractions is used to comment on the current debate whether mechanistic accounts of explanation are compatible with the use of abstractions. This debate has suffered from an abstract discussion of abstractions. With a better taxonomy of abstractions the debate can be resolved.
  • Hundemer, Fabian; von Reventlow, Lorenz Graf; Leonhardt, Celine; Polamo, Mika; Nieger, Martin; Seifermann, Stefan M.; Colsmann, Alexander; Bräse, Stefan (2019)
    We demonstrate modular modifications of the widely employed emitter 2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN) by replacing one or both nitrile acceptors with oxadiazole groups via a tetrazole intermediate. This allows the introduction of various functional groups including halides, alkynes, alkenes, nitriles, esters, ethers and a protected amino acid while preserving the thermally activated delayed fluorescence (TADF) properties. The substituents control the emission maximum of the corresponding emitters, ranging between 472-527 nm, and show high solid-state photoluminescence quantum yields up to 85 %. The TADF emission of two compounds, 4CzCNOXDtBu and 4CzdOXDtBu, a mono- and a bis-oxadiazole substituted 4CzIPN is characterized in detail by time- and temperature-dependent photoluminescence. Solution-processed OLEDs comprising 4CzCNOXDtBu and 4CzdOXDtBu show a significant blue-shift of the emission compared to the reference 4CzIPN, with external quantum efficiencies of 16 %, 5.9 % and 17 % at 100 cd m(-2), respectively.
  • Nurkhametova, Dilyara; Kudryavtsev, Igor; Guselnikova, Valeriia; Serebryakova, Maria; Giniatullina, Raisa R.; Wojciechowski, Sara; Tore, Fatma; Rizvanov, Albert; Koistinaho, Jari; Malm, Tarja; Giniatullin, Rashid (2019)
    Extracellular ATP activates inflammasome and triggers the release of multiple cytokines in various immune cells, a process primarily mediated by P2X7 receptors. However, the expression and functional properties of P2X7 receptors in native mast cells in tissues such as meninges where migraine pain originates from have not been explored. Here we report a novel model of murine cultured meningeal mast cells and using these, as well as easily accessible peritoneal mast cells, studied the mechanisms of ATP-mediated mast cell activation. We show that ATP induced a time and dose-dependent activation of peritoneal mast cells as analyzed by the uptake of organic dye YO-PRO1 as well as 4,6-diamidino-2-phenylindole (DAPI). Both YO-PRO1 and DAPI uptake in mast cells was mediated by the P2X7 subtype of ATP receptors as demonstrated by the inhibitory effect of P2X7 antagonist A839977. Consistent with this, significant YO-PRO1 uptake was promoted by the P2X7 agonist 2',3'-O-(benzoyl-4-benzoyl)-ATP (BzATP). Extracellular ATP-induced degranulation of native and cultured meningeal mast cells was shown with Toluidine Blue staining. Taken together, these data demonstrate the important contribution of P2X7 receptors to ATP-driven activation of mast cells, suggesting these purinergic mechanisms as potential triggers of neuroinflammation and pain sensitization in migraine.
  • Moyano-Galceran, Lidia; Pietila, Elina A.; Turunen, S. Pauliina; Corvigno, Sara; Hjerpe, Elisabet; Bulanova, Daria; Joneborg, Ulrika; Alkasalias, Twana; Miki, Yuichiro; Yashiro, Masakazu; Chernenko, Anastasiya; Jukonen, Joonas; Singh, Madhurendra; Dahlstrand, Hanna; Carlson, Joseph W.; Lehti, Kaisa (2020)
    Metastatic cancers commonly activate adaptive chemotherapy resistance, attributed to both microenvironment-dependent phenotypic plasticity and genetic characteristics of cancer cells. However, the contribution of chemotherapy itself to the non-genetic resistance mechanisms was long neglected. Using high-grade serous ovarian cancer (HGSC) patient material and cell lines, we describe here an unexpectedly robust cisplatin and carboplatin chemotherapy-induced ERK1/2-RSK1/2-EphA2-GPRC5A signaling switch associated with cancer cell intrinsic and acquired chemoresistance. Mechanistically, pharmacological inhibition or knockdown of RSK1/2 prevented oncogenic EphA2-S897 phosphorylation and EphA2-GPRC5A co-regulation, thereby facilitating a signaling shift to the canonical tumor-suppressive tyrosine phosphorylation and consequent downregulation of EphA2. In combination with platinum, RSK inhibitors effectively sensitized even the most platinum-resistant EphA2(high), GPRC5A(high) cells to the therapy-induced apoptosis. In HGSC patient tumors, this orphan receptor GPRC5A was expressed exclusively in cancer cells and associated with chemotherapy resistance and poor survival. Our results reveal a kinase signaling pathway uniquely activated by platinum to elicit adaptive resistance. They further identify GPRC5A as a marker for abysmal HGSC outcome and putative vulnerability of the chemo-resistant cells to RSK1/2-EphA2-pS897 pathway inhibition.
  • Huhtaniemi, Riikka; Oksala, Riikka; Knuuttila, Matias; Mehmood, Arfa; Aho, Eija; Laajala, Teemu D.; Nicorici, Daniel; Aittokallio, Tero; Laiho, Asta; Elo, Laura; Ohlsson, Claes; Kallio, Pekka; Mäkelä, Sari; Mustonen, Mika V. J.; Sipila, Petra; Poutanen, Matti (2018)
    The role of adrenal androgens as drivers for castration-resistant prostate cancer (CRPC) growth in humans is generally accepted; however, the value of preclinical mouse models of CRPC is debatable, because mouse adrenals do not produce steroids activating the androgen receptor. In this study, we confirmed the expression of enzymes essential for de novo synthesis of androgens in mouse adrenals, with high intratissue concentration of progesterone (P-4) and moderate levels of androgens, such as androstenedione, testosterone, and dihydrotestosterone, in the adrenal glands of both intact and orchectomized (ORX) mice. ORX alone had no effect on serum P-4 concentration, whereas orchectomized and adrenalectomized (ORX + ADX) resulted in a significant decrease in serum P-4 and in a further reduction in the Low levels of serum androgens (androstenedione, testosterone, and dihydrotestosterone), measured by mass spectrometry. In line with this, the serum prostate-specific antigen and growth of VCaP xenografts in mice after ORX + ADX were markedly reduced compared with ORX alone, and the growth difference was not abolished by a glucocorticoid treatment. Moreover, ORX + ADX altered the androgen-dependent gene expression in the tumors, similar to that recently shown for the enzalutamide treatment. These data indicate that in contrast to the current view, and similar to humans, mouse adrenals synthesize significant amounts of steroids that contribute to the androgen receptor dependent growth of CRPC.
  • Nováková, Eliška; Zablatzká, Lenka; Brus, Jan; Nesrstová, Viktorie; Hanáček, Pavel; Kalendar, Ruslan; Cvrčková, Fatima; Majeský, Ľuboš; Smýkal, Petr (2019)
    Reproductive isolation is an important component of species differentiation. The plastid accD gene coding for the acetyl-CoA carboxylase subunit and the nuclear bccp gene coding for the biotin carboxyl carrier protein were identified as candidate genes governing nuclear-cytoplasmic incompatibility in peas. We examined the allelic diversity in a set of 195 geographically diverse samples of both cultivated (Pisum sativum, P. abyssinicum) and wild (P. fulvum and P. elatius) peas. Based on deduced protein sequences, we identified 34 accD and 31 bccp alleles that are partially geographically and genetically structured. The accD is highly variable due to insertions of tandem repeats. P. fulvum and P. abyssinicum have unique alleles and combinations of both genes. On the other hand, partial overlap was observed between P. sativum and P. elatius. Mapping of protein sequence polymorphisms to 3D structures revealed that most of the repeat and indel polymorphisms map to sequence regions that could not be modeled, consistent with this part of the protein being less constrained by requirements for precise folding than the enzymatically active domains. The results of this study are important not only from an evolutionary point of view but are also relevant for pea breeding when using more distant wild relatives.
  • Gospodaryov, Dmytro; Strilbytska, Olha M.; Semaniuk, Uliana; Perkhulyn, Natalia; Rovenko, Bohdana M.; Yurkevych, Ihor S.; Barata, Ana G.; Dick, Tobias P.; Lushchak, Oleh; Jacobs, Howard T. (2020)
    Mitochondrial alternative NADH dehydrogenase (aNDH) was found to extend lifespan when expressed in the fruit fly. We have found that fruit flies expressing aNDH from Ciona intestinalis (NDX) had 17-71% lifespan prolongation on media with different protein-tocarbohydrate ratios except NDX-expressing males that had 19% shorter lifespan than controls on a high protein diet. NDX-expressing flies were more resistant to organic xenobiotics, 2,4-dichlorophenoxyacetic acid and alloxan, and inorganic toxicant potassium iodate, and partially to sodium molybdate treatments. On the other hand, NDX-expressing flies were more sensitive to catechol and sodium chromate. Enzymatic analysis showed that NDX-expressing males had higher glucose 6-phosphate dehydrogenase activity, whilst both sexes showed increased glutathione S-transferase activity.
  • Giordano, Luca; Farnham, Antoine; Dhandapani, Praveen K.; Salminen, Laura; Bhaskaran, Jahnavi; Voswinckel, Robert; Rauschkolb, Peter; Scheibe, Susan; Sommer, Natascha; Beisswenger, Christoph; Weissmann, Norbert; Braun, Thomas; Jacobs, Howard T.; Bals, Robert; Herr, Christian; Szibor, Marten (2019)
    Cigarette smoke (CS) exposure is the predominant risk factor for the development of chronic obstructive pulmonary disease (COPD) and the third leading cause of death worldwide. We aimed to elucidate whether mitochondrial respiratory inhibition and oxidative stress are triggers in its etiology. In different models of CS exposure, we investigated the effect on lung remodeling and cell signaling of restoring mitochondrial respiratory electron flow using alternative oxidase (AOX), which bypasses the cytochrome segment of the respiratory chain. AOX attenuated CS-induced lung tissue destruction and loss of function in mice exposed chronically to CS for 9 months. It preserved the cell viability of isolated mouse embryonic fibroblasts treated with CS condensate, limited the induction of apoptosis, and decreased the production of reactive oxygen species (ROS). In contrast, the early-phase inflammatory response induced by acute CS exposure of mouse lung, i.e., infiltration by macrophages and neutrophils and adverse signaling, was unaffected. The use of AOX allowed us to obtain novel pathomechanistic insights into CS-induced cell damage, mitochondrial ROS production, and lung remodeling. Our findings implicate mitochondrial respiratory inhibition as a key pathogenic mechanism of CS toxicity in the lung. We propose AOX as a novel tool to study CS-related lung remodeling and potentially to counteract CS-induced ROS production and cell damage.
  • Sironen, Anu; Uimari, Pekka; Venhoranta, Heli; Andersson, Magnus; Vilkki, Johanna (2011)
    ABSTRACT: BACKGROUND: Male infertility is an increasing problem in all domestic species including man. Localization and identification of genes involved in defects causing male infertility provide valuable information of specific events in sperm development. Sperm development is a complex process, where diploid spermatogonia develop into haploid, highly specialized spermatozoa. Correct expression and function of various genes and their protein products are required for production of fertile sperm. We have identified an infertility defect in Finnish Yorkshire boars caused by spermatogenic arrest. The aim of this study was to locate the disease associated region using genome wide screen with the PorcineSNP60 Beadchip and identify the causal mutation by candidate gene approach. RESULTS: In the Finnish Yorkshire pig population the spermatogenic arrest (SA) defect appears to be of genetic origin and causes severe degeneration of germ cells and total absence of spermatozoa. Genome wide scan with the PorcineSNP60 Beadchip localized the SA defect to porcine chromosome 12 in a 2 Mbp region. Sequencing of a candidate gene Tex14 revealed a 51 bp insertion within exon 27, which caused differential splicing of the exon and created a premature translation stop codon. The expression of Tex14 was markedly down regulated in the testis of a SA affected boar compared to control boars and no protein product was identified by Western blotting. The SA insertion sequence was also found within intron 27 in all analyzed animals, thus the insertion appears to be a possible duplication event. CONCLUSION: In this study we report the identification of a causal mutation for infertility caused by spermatogenic arrest at an early meiotic phase. Our results highlight the role of TEX14 specifically in spermatogenesis and the importance of specific genomic remodeling events as causes for inherited defects.
  • Hamari, S.; Kirveskoski, T.; Glumoff, V.; Kulmala, P.; Simell, O.; Knip, M.; Veijola, R. (2016)
    Our aim was to study whether the aberrant amount or function of regulatory T cells is related to the development of type 1 diabetes (T1D) in children. We also set out to investigate the balance of different T cell subtype markers during the T1D autoimmune process. Treg cells were quantified with flow cytometric assay, and the suppression capacity was analysed with a carboxyfluorescein succinimidyl ester (CFSE)-based T cell suppression assay in children in various phases of T1D disease process and in healthy autoantibody-negative control children. The mRNA expression of different T cell subpopulation markers was analysed with real-time qPCR method. The proportion and suppression capacity of regulatory T cells were similar in seroconverted children at an early stage of beta cell autoimmunity and also in children with T1D when compared to healthy and autoantibody-negative children. Significant differences were observed in the mRNA expression of different T cell subpopulation markers in prediabetic children with multiple (2) autoantibodies and in children with newly diagnosed T1D when compared to the control children. In conclusion, there were no quantitative or functional differences in regulatory T cells between the case and control groups in any phase of the autoimmune process. Decreased mRNA expression levels of T cell subtype markers were observed in children with multiple islet autoantibodies and in those with newly diagnosed T1D, probably reflecting an exhaustion of the immune system after the strong immune activation during the autoimmune process or a generally aberrant immune response related to the progression of the disease.
  • Soikkeli, Maiju; Kettunen, Mikko I.; Nivajärvi, Riikka; Olsson, Venla; Ronkko, Seppo; Laakkonen, Johanna P.; Lehto, Vesa-Pekka; Kavakka, Jari; Heikkinen, Sami (2019)
    Magnetic resonance imaging examinations are frequently carried out using contrast agents to improve the image quality. Practically all clinically used contrast agents are based on paramagnetic metals and lack in selectivity and specificity. A group of stable organic radicals, nitroxides, has raised interest as new metal-free contrast agents for MRI. Their structures can easily be modified to incorporate different functionalities. In the present study, a stable nitroxide TEEPO (2,2,6,6-tetraethylpiperidin-1-oxyl) was linked to a glucose moiety (Glc) to construct a water-soluble, potentially tumor-targeting compound with contrast-enhancing ability. The ability was assessed with in vivo MRI experiments. The constructed TEEPO-Glc agent proved to shorten the T-1 relaxation time in tumor, while the T-1 time in healthy brain tissue remained the same. The results indicate the potential of TEEPO-Glc as a valuable addition to the growing field of metal-free contrast enhancement in MRI-based diagnostics.
  • Karhula, Kati; Harma, Mikko; Sallinen, Mikael; Lindholm, Harri; Hirvonen, Ari; Elovainio, Marko; Kivimaki, Mika; Vahtera, Jussi; Puttonen, Sampsa (2016)
    Although the prevalence of work-related stress has increased, knowledge on the contributions of that stress to long-term adverse health effects is still lacking. Stress biomarkers can reveal early signs of negative health effects, but no previous studies have measured both acute stress reactions and long-term exposure to job strain using both salivary cortisol and -amylase (AA). The present study examines the association between job strain and these biomarkers among shift-working female health care professionals in the laboratory and the field. The 95 participants were recruited from hospital wards categorized in either the top (high job strain [HJS] group, n = 42) or the bottom quartile of job strain (low job strain [LJS] group, n = 53), as rated by survey responses. Participants' self-perceived job strain was at least as high or low as the ward's average estimation. Saliva samples were collected during the Trier Social Stress Test (TSST), preselected morning and night shifts, and a day off. There was a larger increase in the cortisol concentration of participants in the HJS than in the LJS group (2.27- vs. 1.48-fold, respectively, nonsignificant) during the TSST. Participants in the HJS group also had higher salivary AA levels 30 min after awakening on the morning-shift day than those in the LJS group (p = .02), whereas the salivary cortisol awakening response on the day off was higher in the LJS group (p = .05, education as a covariate). The remaining stress-biomarker results did not differ significantly between groups. These data suggest that HJS in shift-working health care professionals is weakly associated with changes in stress biomarkers.
  • Hultsch, Susanne; Kankainen, Matti; Paavolainen, Lassi; Kovanen, Ruusu-Maaria; Ikonen, Elina; Kangaspeska, Sara; Pietiäinen, Vilja; Kallioniemi, Olli (2018)
    Background: Tamoxifen treatment of estrogen receptor (ER)-positive breast cancer reduces mortality by 31%. However, over half of advanced ER-positive breast cancers are intrinsically resistant to tamoxifen and about 40% will acquire the resistance during the treatment. Methods: In order to explore mechanisms underlying endocrine therapy resistance in breast cancer and to identify new therapeutic opportunities, we created tamoxifen-resistant breast cancer cell lines that represent the luminal A or the luminal B. Gene expression patterns revealed by RNA-sequencing in seven tamoxifen-resistant variants were compared with their isogenic parental cells. We further examined those transcriptomic alterations in a publicly available patient cohort Results: We show that tamoxifen resistance cannot simply be explained by altered expression of individual genes, common mechanism across all resistant variants, or the appearance of new fusion genes. Instead, the resistant cell lines shared altered gene expression patterns associated with cell cycle, protein modification and metabolism, especially with the cholesterol pathway. In the tamoxifen-resistant T-47D cell variants we observed a striking increase of neutral lipids in lipid droplets as well as an accumulation of free cholesterol in the lysosomes. Tamoxifen-resistant cells were also less prone to lysosomal membrane permeabilization (LMP) and not vulnerable to compounds targeting the lipid metabolism. However, the cells were sensitive to disulfiram, LCS-1, and dasatinib. Conclusion: Altogether, our findings highlight a major role of LMP prevention in tamoxifen resistance, and suggest novel drug vulnerabilities associated with this phenotype.
  • Tyrrell, Nicholas L.; Karpechko, Alexey Yu.; Uotila, Petteri; Vihma, Timo (2019)
    Abstract: The warm Arctic-cold continent pattern was of record strength in October 2016, providing the opportunity to test its proposed influence on large-scale atmospheric circulation. We find a record weak polar stratospheric vortex and negative North Atlantic Oscillation in November-December 2016 and link them to increased planetary wave generation associated with cold Siberian anomalies followed by troposphere-stratosphere dynamical coupling. At the same time the warm Arctic anomalies, in particular those over the Barents-Kara Seas, do not appear to play an important role in forcing the atmospheric circulation. Long-range forecasts initialized on 1 October 2016 reproduced both the weak polar vortex and negative North Atlantic Oscillation, as well as their link with the Siberian temperatures. Our results support the stratospheric pathway for atmospheric circulation forcing associated with Siberian surface anomalies and uncover a source of skill for subseasonal forecasts from October to December. Plain Language Summary: The warm Arctic-cold continent pattern is an observed, large-scale pattern of near-surface temperatures where the Arctic is warmer than average and Siberia is colder than average. This pattern was of record strength in October 2016, providing the opportunity to test its influence on the Northern Hemisphere atmospheric circulation and the possibility of skillful long-range forecasts. It has been proposed that the warm Arctic-cold continent pattern can drive large atmospheric waves, which are able to travel from the troposphere into the stratosphere, where they weaken the strong wintertime winds that make up the stratospheric polar vortex. A weakened polar vortex can then lead to changes in the surface pressure that can affect weather patterns. We find a record weak polar stratospheric vortex in late autumn 2016 and link that to cold Siberian anomalies. At the same time the warm Arctic anomalies do not appear to play an important role in forcing the atmospheric circulation. Long-range forecasts initialized in October 2016 reproduced both the weak polar vortex and resulting surface pressure patterns. Our results support the stratospheric pathway for atmospheric circulation forcing by Siberian surface anomalies and uncover a source of skill for subseasonal forecasts in the Northern Hemisphere autumn.
  • Landolt, Lea; Furriol, Jessica; Babickova, Janka; Ahmed, Lavina; Eikrem, Oystein; Skogstrand, Trude; Scherer, Andreas; Suliman, Salwa; Leh, Sabine; Lorens, J. B.; Gausdal, Gro; Marti, H.P.; Osman, Tarig (2019)
    The AXL receptor tyrosine kinase (RTK) is involved in partial epithelial-to-mesenchymal transition (EMT) and inflammation - both main promoters of renal fibrosis development. The study aim was to investigate the role of AXL inhibition in kidney fibrosis due to unilateral ureteral obstruction (UUO). Eight weeks old male C57BL/6 mice underwent UUO and were treated with oral AXL inhibitor bemcentinib (n = 22), Angiotensin-converting enzyme inhibitor (ACEI, n = 10), ACEI and bemcentinib (n = 10) or vehicle alone (n = 22). Mice were sacrificed after 7 or 15 days and kidney tissues were analyzed by immunohistochemistry (IHC), western blot, ELISA, Sirius Red (SR) staining, and hydroxyproline (Hyp) quantification. RNA was extracted from frozen kidney tissues and sequenced on an Illumina HiSeq4000 platform. After 15 days the ligated bemcentinib-treated kidneys showed less fibrosis compared to the ligated vehicle-treated kidneys in SR analyses and Hyp quantification. Reduced IHC staining for Vimentin (VIM) and alpha smooth muscle actin (alpha SMA), as well as reduced mRNA abundance of key regulators of fibrosis such as transforming growth factor (Tgf beta), matrix metalloproteinase 2 (Mmp2), Smad2, Smad4, myofibroblast activation (Aldh1a2, Crlf1), and EMT (Snai1,2, Twist), in ligated bemcentinib-treated kidneys was compatible with reduced (partial) EMT induction. Furthermore, less F4/80 positive cells, less activity of pathways related to the immune system and lower abundance of MCP1, MCP3, MCP5, and TARC in ligated bemcentinib-treated kidneys was compatible with reduction in inflammatory infiltrates by bemcentinib treatment. The AXL RTK pathway represents a promising target for pharmacologic therapy of kidney fibrosis.