Browsing by Subject "RECEPTOR"

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  • Pryce, Rhys; Azarm, Kristopher; Rissanen, Ilona; Harlos, Karl; Bowden, Thomas A.; Lee, Benhur (2020)
    The emergent zoonotic henipaviruses, Hendra, and Nipah are responsible for frequent and fatal disease outbreaks in domestic animals and humans. Specificity of henipavirus attachment glycoproteins (G) for highly species-conserved ephrin ligands underpins their broad host range and is associated with systemic and neurological disease pathologies. Here, we demonstrate that Cedar virus (CedV)—a related henipavirus that is ostensibly nonpathogenic—possesses an idiosyncratic entry receptor repertoire that includes the common henipaviral receptor, ephrin-B2, but, distinct from pathogenic henipaviruses, does not include ephrin-B3. Uniquely among known henipaviruses, CedV can use ephrin-B1 for cellular entry. Structural analyses of CedV-G reveal a key region of molecular specificity that directs ephrin-B1 utilization, while preserving a universal mode of ephrin-B2 recognition. The structural and functional insights presented uncover diversity within the known henipavirus receptor repertoire and suggest that only modest structural changes may be required to modulate receptor specificities within this group of lethal human pathogens.
  • Ardashov, Oleg V.; Pavlova, Alla V.; Mahato, Arun Kumar; Sidorova, Yulia; Morozova, Ekaterina A.; Korchagina, Dina V.; Salnikov, Georgi E.; Genaev, Alexander M.; Patrusheva, Oksana S.; Li-Zhulanov, Nikolay S.; Tolstikova, Tat'yana G.; Volcho, Konstantin P.; Salakhutdinov, Nariman. F. (2019)
    We previously showed that monoterpenoid (1R,2R,6S)-3-methyl-6-(prop-1-en-2-yl)cyclohex-3-ene-1,2-diol 1 alleviates motor manifestations of Parkinson's disease in animal models. In the present study, we designed and synthesized monoepoxides of (1R,2R,6S)-3-methyl-6-(prop-1-en-2-yl)cyclohex-3-ene-1,2-diol 1 and evaluated their biological activity in the MPTP mouse model of Parkinson's disease. We also assessed the ability of these compounds to penetrate the blood-brain barrier (BBB). According to these data, we chose epoxide 4, which potently restored the locomotor activity in MPTP-treated mice and efficiently penetrated the BBB, to further explore its potential mechanism of action. Epoxide 4 was found to robustly promote the survival of cultured dopamine neurons, protect dopamine neurons against toxin-induced degeneration, and trigger the mitogen-activated protein kinase (MAPK) signaling cascade in cells of neuronal origin. Meanwhile, neither the survival-promoting effect nor MAPK activation was observed in non-neuronal cells treated with epoxide 4. In the MPTP mouse model of Parkinson's disease, compound 4 increased the density of dopamine neuron fibers in the striatum, which can highlight its potential to stimulate striatal reinnervation and thus halt disease progression. Taken together, these data indicate that epoxide 4 can be a promising compound for further development, not only as a symptomatic but also as a neuroprotective and neurorestorative drug for Parkinson's disease.
  • Zhang, Yuezhou; Jumppanen, Antti Mikael; Maksimainen, Mirko M.; Auno, Atte Samuli; Awol, Zulfa; Ghemtio, Leo; Venkannagari, Harikanth; Lehtiö, Lari; Yli-Kauhaluoma, Jari; Xhaard, Henri; Boije af Gennäs, Gustav (2018)
    The human O-acetyl-ADP-ribose deacetylase MDO1 is a mono-ADP-ribosylhydrolase involved in the reversal of post-translational modifications. Until now MDO1 has been poorly characterized, partly since no ligand is known besides adenosine nucleotides. Here, we synthesized thirteen compounds retaining the adenosine moiety and bearing bioisosteric replacements of the phosphate at the ribose 50-oxygen. These compounds are composed of either a squaryldiamide or an amide group as the bioisosteric replacement and/or as a linker. To these groups a variety of substituents were attached such as phenyl, benzyl, pyridyl, carboxyl, hydroxy and tetrazolyl. Biochemical evaluation showed that two compounds, one from both series, inhibited ADP-ribosyl hydrolysis mediated by MDO1 in high concentrations. (C) 2018 Elsevier Ltd. All rights reserved.
  • Flatt, Justin W.; Butcher, Sarah J. (2019)
    Viruses are obligatory parasites that take advantage of intracellular niches to replicate. During infection, their genomes are carried in capsids across the membranes of host cells to sites of virion production by exploiting cellular behaviour and resources to guide and achieve all aspects of delivery and the downstream virus manufacturing process. Successful entry hinges on execution of a precisely tuned viral uncoating program where incoming capsids disassemble in consecutive steps to ensure that genomes are released at the right time, and in the right place for replication to occur. Each step of disassembly is cell-assisted, involving individual pathways that transmit signals to regulate discrete functions, but at the same time, these signalling pathways are organized into larger networks, which communicate back and forth in complex ways in response to the presence of virus. In this review, we consider the elegant strategy by which adenoviruses (AdVs) target and navigate cellular networks to initiate the production of progeny virions. There are many remarkable aspects about the AdV entry program; for example, the virus gains targeted control of a large well-defined local network neighbourhood by coupling several interacting processes (including endocytosis, autophagy and microtubule trafficking) around a collective reference state centred on the interactional topology and multifunctional nature of protein VI. Understanding the network targeting activity of protein VI, as well as other built-in mechanisms that allow AdV particles to be efficient at navigating the subsystems of the cell, can be used to improve viral vectors, but also has potential to be incorporated for use in entirely novel delivery systems.
  • Lavilla-Alonso, Sergio; Bauerschmitz, Gerd; Abo-Ramadan, Usama; Halavaara, Juha; Escutenaire, Sophie; Diaconu, Iulia; Tatlisumak, Turgut; Kanerva, Anna; Hemminki, Akseli; Pesonen, Sari (2010)
  • Acheva, Anna; Kärki, Tytti; Schaible, Niccole; Krishnan, Ramaswamy; Tojkander, Sari (2021)
    In postmenopausal women, a major risk factor for the development of breast cancer is obesity. In particular, the adipose tissue-derived adipokine leptin has been strongly linked to tumor cell proliferation, migration, and metastasis, but the underlying mechanisms remain unclear. Here we show that treatment of normal mammary epithelial cells with leptin induces EMT-like features characterized by higher cellular migration speeds, loss of structural ordering of 3D-mammo spheres, and enhancement of epithelial traction forces. Mechanistically, leptin triggers the phosphorylation of myosin light chain kinase-2 (MLC-2) through the interdependent activity of leptin receptor and Ca2+ channels. These data provide evidence that leptin-activated leptin receptors, in co-operation with mechanosensitive Ca2+ channels, play a role in the development of breast carcinomas through the regulation of actomyosin dynamics.
  • Eriksson, Mia D.; Eriksson, Johan G.; Kautiainen, Hannu; Salonen, Minna K.; Mikkola, Tuija M.; Kajantie, Eero; Wasenius, Niko; von Bonsdorff, Mikaela; Laine, Merja K. (2021)
    Background: Millions of people live with depression and its burden of disease. Depression has an increased comorbidity and mortality that has remained unexplained. Studies have reported connections between advanced glycation end products (AGEs) and various disease processes, including mental health. The present study evaluated associations between AGEs, depressive symptoms, and types of depressive symptoms. Methods: From the Helsinki Birth Cohort Study, 815 participants with a mean age of 76 years were recruited for this cross-sectional study. Characteristics regarding self-reported lifestyle and medical history, as well as blood tests were obtained along with responses regarding depressive symptoms according to the Beck Depression Inventory (BDI) and Mental Health Inventory-5. Each participant had their AGE level measured non-invasively with skin autofluorescence (SAF). Statistical analyses looked at relationships between types of depressive symptoms and AGE levels by sex. Results: Of women, 27% scored >= 10 on the BDI and 18% of men, respectively. Men had higher crude AGE levels (mean [standard deviation], arbitrary units) (2.49 [0.51]) compared to women (2.33 [0.46]) (p < 0.001). The highest crude AGE levels were found in those with melancholic depressive symptoms (2.61 [0.57]), followed by those with non-melancholic depressive symptoms (2.45 [0.45]) and those with no depressive symptoms (2.38 [0.49]) (p = 0.013). These findings remained significant in the fully adjusted model. Conclusions: The current study shows an association between depressive symptoms and higher AGE levels. The association is likely part of a multi-factorial effect, and hence no directionality, causality, or effect can be inferred solely based on the results of this study.
  • Timperley, Christopher M.; Forman, Jonathan E.; Aas, Pal; Abdollahi, Mohammad; Benachour, Djafer; Al-Amri, Abdullah Saeed; Baulig, Augustin; Becker-Arnold, Renate; Borrett, Veronica; Carino, Flerida A.; Curty, Christophe; Gonzalez, David; Geist, Michael; Kane, William; Kovarik, Zrinka; Martinez-Alvarez, Roberto; Mikulak, Robert; Fusaro Mourao, Nicia Maria; Neffe, Slawomir; Nogueira, Evandro De Souza; Ramasami, Ponnadurai; Raza, Syed K.; Rubaylo, Valentin; Saeed, Ahmed E. M.; Takeuchi, Koji; Tang, Cheng; Trifiro, Ferruccio; van Straten, Francois Mauritz; Suarez, Alejandra G.; Waqar, Farhat; Vanninen, Paula S.; Zafar-Uz-Zaman, Mohammad; Vucinic, Slavica; Zaitsev, Volodymyr; Zina, Mongia Said; Holen, Stian; Izzati, Fauzia Nurul (2018)
    Compounds that cause powerful sensory irritation to humans were reviewed by the Scientific Advisory Board (SAB) of the Organisation for the Prohibition of Chemical Weapons (OPCW) in response to requests in 2014 and 2017 by the OPCW Director-General to advise which riot control agents (RCAs) might be subject to declaration under the Chemical Weapons Convention (the Convention). The chemical and toxicological properties of 60 chemicals identified from a survey by the OPCW of RCAs that had been researched or were available for purchase, and additional chemicals recognised by the SAB as having potential RCA applications, were considered. Only 17 of the 60 chemicals met the definition of a RCA under the Convention. These findings were provided to the States Parties of the Convention to inform the implementation of obligations pertaining to RCAs under this international chemical disarmament and non-proliferation treaty.
  • PanScan PanC4 consortia; Walsh, Naomi; Zhang, Han; Männistö, Satu; Weiderpass, Elisabete (2019)
    Background Genome-wide association studies (GWAS) identify associations of individual single-nucleotide polymorphisms (SNPs) with cancer risk but usually only explain a fraction of the inherited variability. Pathway analysis of genetic variants is a powerful tool to identify networks of susceptibility genes. Methods We conducted a large agnostic pathway-based meta-analysis of GWAS data using the summary-based adaptive rank truncated product method to identify gene sets and pathways associated with pancreatic ductal adenocarcinoma (PDAC) in 9040 cases and 12 496 controls. We performed expression quantitative trait loci (eQTL) analysis and functional annotation of the top SNPs in genes contributing to the top associated pathways and gene sets. All statistical tests were two-sided. Results We identified 14 pathways and gene sets associated with PDAC at a false discovery rate of less than 0.05. After Bonferroni correction (P Conclusion Our agnostic pathway and gene set analysis integrated with functional annotation and eQTL analysis provides insight into genes and pathways that may be biologically relevant for risk of PDAC, including those not previously identified.
  • Lainiola, Mira; Linden, Anni-Maija (2017)
    Neuroinflammation may play an important role in the development of alcohol addiction. Recent pre-clinical reports suggest that enhanced innate immune system signaling increases consumption of alcohol. Our aim was to study whether consequences of lipopolysaccharide (LPS)-induced sickness reaction increase long-term alcohol intake. Adult male C57BL/6j mice, housed in individually ventilated cages, were injected with LPS intraperitoneally (i.p.) and allowed to recover from an acute sickness reaction for 1 week before analysis of their alcohol intake in two different drinking models. Effects of LPS challenge were tested in a continuous two-bottle free choice test with increasing concentrations of alcohol and in a drinking in the dark (DID) binge model. In addition, the effect of repeatedly administered LPS during abstinence periods between binge drinking was analyzed in the DID model. In addition, the DID model was used to study the effects of the microglia inhibitor minocycline (50 mg/kg/day, 4 days) and purinergic P2X7 receptor antagonist Brilliant Blue G (75 mg/kg/day, 7 days) on alcohol intake. In contrast to previous findings, pretreatment with a 1-mg/kg dose of LPS did not significantly increase ethanol consumption in the continuous two-bottle choice test. As a novel finding, we report that increasing the LPS dose to 1.5 mg/kg reduced consumption of 18 and 21% (v/v) ethanol. In the DID model, pretreatment with LPS (0.2-1.5 mg/kg) did not significantly alter 15% or 20% ethanol consumption. Neither did repeated LPS injections affect binge alcohol drinking. Minocycline reduced alcohol, but also water, intake regardless of LPS pretreatment. No data on effects of P2X7 antagonists on alcohol consumption have been previously published; therefore, we report here that subchronic Brilliant Blue G had no effect on alcohol intake in the DID model. As a conclusion, further studies are needed to validate this LPS model of the interaction between immune system activation and alcohol consumption. (C) 2017 Elsevier Inc. All rights reserved.
  • Aminoff, Anna; Ledmyr, Helena; Thulin, Petra; Lundell, Kerstin; Nunez, Leyla; Strandhagen, Elisabeth; Murphy, Charlotte; Lidberg, Ulf; Westerbacka, Jukka; Franco-Cereceda, Anders; Liska, Jan; Nielsen, Lars Bo; Gafvels, Mats; Mannila, Maria Nastase; Hamsten, Anders; Yki-Järvinen, Hannele; Thelle, Dag; Eriksson, Per; Boren, Jan; Ehrenborg, Ewa (2010)
  • Simonen, P.; Li, S.; Chua, N. K.; Lampi, A-M; Piironen, V.; Lommi, J.; Sinisalo, J.; Brown, A. J.; Ikonen, E.; Gylling, H. (2020)
    Background We have earlier reported that amiodarone, a potent and commonly used antiarrhythmic drug increases serum desmosterol, the last precursor of cholesterol, in 20 cardiac patients by an unknown mechanism. Objective Here, we extended our study to a large number of cardiac patients of heterogeneous diagnoses, evaluated the effects of combining amiodarone and statins (inhibitors of cholesterol synthesis at the rate-limiting step of hydroxy-methyl-glutaryl CoA reductase) on desmosterol levels and investigated the mechanism(s) by which amiodarone interferes with the metabolism of desmosterol using in vitro studies. Methods and Results We report in a clinical case-control setting of 236 cardiac patients (126 with and 110 without amiodarone treatment) that amiodarone medication is accompanied by a robust increase in serum desmosterol levels independently of gender, age, body mass index, cardiac and other diseases, and the use of statins. Lipid analyses in patient samples taken before and after initiation of amiodarone therapy showed a systematic increase of desmosterol upon drug administration, strongly arguing for a direct causal link between amiodarone and desmosterol accumulation. Mechanistically, we found that amiodarone resulted in desmosterol accumulation in cultured human cells and that the compound directly inhibited the 24-dehydrocholesterol reductase (DHCR24) enzyme activity. Conclusion These novel findings demonstrate that amiodarone blocks the cholesterol synthesis pathway by inhibiting DHCR24, causing a robust accumulation of cellular desmosterol in cells and in the sera of amiodarone-treated patients. It is conceivable that the antiarrhythmic potential and side effects of amiodarone may in part result from inhibition of the cholesterol synthesis pathway.
  • Nath, Artika P.; Ritchie, Scott C.; Byars, Sean G.; Fearnley, Liam G.; Havulinna, Aki S.; Joensuu, Anni; Kangas, Antti J.; Soininen, Pasi; Wennerstrom, Annika; Milani, Lili; Metspalu, Andres; Mannisto, Satu; Wurtz, Peter; Kettunen, Johannes; Raitoharju, Emma; Kahonen, Mika; Juonala, Markus; Palotie, Aarno; Ala-Korpela, Mika; Ripatti, Samuli; Lehtimaki, Terho; Abraham, Gad; Raitakari, Olli; Salomaa, Veikko; Perola, Markus; Inouye, Michael (2017)
    Background: Immunometabolism plays a central role in many cardiometabolic diseases. However, a robust map of immune-related gene networks in circulating human cells, their interactions with metabolites, and their genetic control is still lacking. Here, we integrate blood transcriptomic, metabolomic, and genomic profiles from two population-based cohorts (total N = 2168), including a subset of individuals with matched multi-omic data at 7-year follow-up. Results: We identify topologically replicable gene networks enriched for diverse immune functions including cytotoxicity, viral response, B cell, platelet, neutrophil, and mast cell/basophil activity. These immune gene modules show complex patterns of association with 158 circulating metabolites, including lipoprotein subclasses, lipids, fatty acids, amino acids, small molecules, and CRP. Genome-wide scans for module expression quantitative trait loci (mQTLs) reveal five modules with mQTLs that have both cis and trans effects. The strongest mQTL is in ARHGEF3 (rs1354034) and affects a module enriched for platelet function, independent of platelet counts. Modules of mast cell/basophil and neutrophil function show temporally stable metabolite associations over 7-year follow-up, providing evidence that these modules and their constituent gene products may play central roles in metabolic inflammation. Furthermore, the strongest mQTL in ARHGEF3 also displays clear temporal stability, supporting widespread trans effects at this locus. Conclusions: This study provides a detailed map of natural variation at the blood immunometabolic interface and its genetic basis, and may facilitate subsequent studies to explain inter-individual variation in cardiometabolic disease.
  • Hattula, Katarina; Hirschberg, Daniel; Kalkkinen, Nisse; Butcher, Sarah J.; Ora, Ari (2014)
  • Tynkkynen, Juho; Chouraki, Vincent; van der Lee, Sven J.; Hernesniemi, Jussi; Yang, Qiong; Li, Shuo; Beiser, Alexa; Larson, Martin G.; Sääksjärvi, Katri; Shipley, Martin J.; Singh-Manoux, Archana; Gerszten, Robert E.; Wang, Thomas J.; Havulinna, Aki S.; Würtz, Peter; Fischer, Krista; Demirkan, Ayse; Ikram, M. Arfan; Amin, Najaf; Lehtimäki, Terho; Kähönen, Mika; Perola, Markus; Metspalu, Andres; Kangas, Antti J.; Soininen, Pasi; Ala-Korpela, Mika; Vasan, Ramachandran S.; Kivimäki, Mika; van Duijn, Cornelia M.; Seshadri, Sudha; Salomaa, Veikko (2018)
    Introduction: Metabolite, lipid, and lipoprotein lipid profiling can provide novel insights into mechanisms underlying incident dementia and Alzheimer's disease. Methods: We studied eight prospective cohorts with 22,623 participants profiled by nuclear magnetic resonance or mass spectrometry metabolomics. Four cohorts were used for discovery with replication undertaken in the other four to avoid false positives. For metabolites that survived replication, combined association results are presented. Results: Over 246,698 person-years, 995 and 745 cases of incident dementia and Alzheimer's disease were detected, respectively. Three branched-chain amino acids (isoleucine, leucine, and valine), creatinine and two very low density lipoprotein (VLDL)-specific lipoprotein lipid subclasses were associated with lower dementia risk. One high density lipoprotein (HDL; the concentration of cholesterol esters relative to total lipids in large HDL) and one VLDL (total cholesterol to total lipids ratio in very large VLDL) lipoprotein lipid subclass was associated with increased dementia risk. Branched-chain amino acids were also associated with decreased Alzheimer's disease risk and the concentration of cholesterol esters relative to total lipids in large HDL with increased Alzheimer's disease risk. Discussion: Further studies can clarify whether these molecules play a causal role in dementia pathogenesis or are merely markers of early pathology. (C) 2018 The Authors. Published by Elsevier Inc. on behalf of the Alzheimer's Association.
  • Hernandez-Perez, Sara; Vainio, Marika; Kuokkanen, Elina; Sustar, Vid; Petrov, Petar; Forsten, Sofia; Paavola, Vilma; Rajala, Johanna; Awoniyi, Luqman O.; Sarapulov, Alexey; Vihinen, Helena; Jokitalo, Eija; Bruckbauer, Andreas; Mattila, Pieta K. (2020)
    In order to mount high-affinity antibody responses, B cells internalise specific antigens and process them into peptides loaded onto MHCII for presentation to T helper cells (T H cells). While the biochemical principles of antigen processing and MHCII loading have been well dissected, how the endosomal vesicle system is wired to enable these specific functions remains much less studied. Here, we performed a systematic microscopy-based analysis of antigen trafficking in B cells to reveal its route to the MHCII peptide-loading compartment (MIIC). Surprisingly, we detected fast targeting of internalised antigen into peripheral acidic compartments that possessed the hallmarks of the MIIC and also showed degradative capacity. In these vesicles, intemalised antigen converged rapidly with membrane-derived MHCII and partially overlapped with cathepsin-S and H2-M, both required for peptide loading. These early compartments appeared heterogenous and atypical as they contained a mixture of both early and late endosomal markers, indicating a specialized endosomal route. Together, our data suggest that, in addition to in the previously reported perinuclear late endosomal MIICs, antigen processing and peptide loading could have already started in these specialized early peripheral acidic vesicles (eMlIC) to support fast peptide-MHCII presentation. This article has an associated First Person interview with the first author of the paper.
  • Puskarjov, Martin; Ahmad, Faraz; Khirug, Stanislav; Sivakumaran, Sudhir; Kaila, Kai; Blaesse, Peter (2015)
  • Leppänen, Veli-Matti; Brouillard, Pascal; Korhonen, Emilia A.; Sipilä, Tuomas; Jha, Sawan Kumar; Revencu, Nicole; Labarque, Veerle; Fastré, Elodie; Schlögel, Matthieu; Ravoet, Marie; Singer, Amihood; Luzzatto, Claudia; Angelone, Donatella; Crichiutti, Giovanni; D’Elia, Angela; Kuurne, Jaakko; Elamaa, Harri; Koh, Gou Young; Saharinen, Pipsa; Vikkula, Miikka; Alitalo, Kari (2020)
    Lymphedema can occur when tissue fluid cannot enter or leaks from the lymphatic system into surrounding tissues. Some genetic causes of primary lymphedema are known, but these currently explain a minority of cases. Previous studies have shown that dominant-negative mutations in angiopoietin 2 (ANGPT2), which is involved in lymphatic vessel formation and maturation, promote lymphangiogenesis in mice. Leppänen et al. now show that inactivating mutations in angiopoietin 2 associate with primary lymphedema in humans.Primary lymphedema is caused by developmental and functional defects of the lymphatic vascular system that result in accumulation of protein-rich fluid in tissues, resulting in edema. The 28 currently known genes causing primary lymphedema can explain &lt;30% of cases. Angiopoietin 1 (ANGPT1) and ANGPT2 function via the TIE1-TIE2 (tyrosine kinase with immunoglobulin-like and epidermal growth factor–like domains 1 and 2) receptor complex and α5β1 integrin to form an endothelial cell signaling pathway that is critical for blood and lymphatic vessel formation and remodeling during embryonic development, as well as for homeostasis of the mature vasculature. By screening a cohort of 543 individuals affected by primary lymphedema, we identified one heterozygous de novo ANGPT2 whole-gene deletion and four heterozygous ANGPT2 missense mutations. Functional analyses revealed three missense mutations that resulted in decreased ANGPT2 secretion and inhibited the secretion of wild-type (WT)–ANGPT2, suggesting that they have a dominant-negative effect on ANGPT2 signaling. WT-ANGPT2 and soluble mutants T299M and N304K activated TIE1 and TIE2 in an autocrine assay in human lymphatic endothelial cells. Molecular modeling and biophysical studies showed that amino-terminally truncated ANGPT subunits formed asymmetrical homodimers that bound TIE2 in a 2:1 ratio. The T299M mutant, located in the dimerization interphase, showed reduced integrin α5 binding, and its expression in mouse skin promoted hyperplasia and dilation of cutaneous lymphatic vessels. These results demonstrate that primary lymphedema can be associated with ANGPT2 mutations and provide insights into TIE1 and TIE2 activation mechanisms.
  • Raivola, Juuli; Haikarainen, Teemu; Silvennoinen, Olli (2020)
    The Janus kinase-signal transducer and activator of transcription protein (JAK-STAT) pathway mediates essential biological functions from immune responses to haematopoiesis. Deregulated JAK-STAT signaling causes myeloproliferative neoplasms, leukaemia, and lymphomas, as well as autoimmune diseases. Thereby JAKs have gained significant relevance as therapeutic targets. However, there is still a clinical need for better JAK inhibitors and novel strategies targeting regions outside the conserved kinase domain have gained interest. In-depth knowledge about the molecular details of JAK activation is required. For example, whether the function and regulation between receptors is conserved remains an open question. We used JAK-deficient cell-lines and structure-based mutagenesis to study the function of JAK1 and its pseudokinase domain (JH2) in cytokine signaling pathways that employ JAK1 with different JAK heterodimerization partner. In interleukin-2 (IL-2)-induced STAT5 activation JAK1 was dominant over JAK3 but in interferon-gamma (IFN gamma) and interferon-alpha (IFN alpha) signaling both JAK1 and heteromeric partner JAK2 or TYK2 were both indispensable for STAT1 activation. Moreover, IL-2 signaling was strictly dependent on both JAK1 JH1 and JH2 but in IFN gamma signaling JAK1 JH2 rather than kinase activity was required for STAT1 activation. To investigate the regulatory function, we focused on two allosteric regions in JAK1 JH2, the ATP-binding pocket and the alpha C-helix. Mutating L633 at the alpha C reduced basal and cytokine induced activation of STAT in both JAK1 wild-type (WT) and constitutively activated mutant backgrounds. Moreover, biochemical characterization and comparison of JH2s let us depict differences in the JH2 ATP-binding and strengthen the hypothesis that de-stabilization of the domain disturbs the regulatory JH1-JH2 interaction. Collectively, our results bring mechanistic understanding about the function of JAK1 in different receptor complexes that likely have relevance for the design of specific JAK modulators.
  • Lund, Carina; Yellapragada, Venkatram; Vuoristo, Sanna; Balboa, Diego; Trova, Sara; Allet, Cecile; Eskici, Nazli; Pulli, Kristiina; Giacobini, Paolo; Tuuri, Timo; Raivio, Taneli (2020)
    Gonadotropin-releasing hormone (GnRH) neurons provide a fundamental signal for the onset of puberty and subsequent reproductive functions by secretion of gonadotropin-releasing hormone. Their disrupted development or function leads to congenital hypogonadotropic hypogonadism (CHH). To model the development of human GnRH neurons, we generated a stable GNRH1-TdTomato reporter cell line in human pluripotent stem cells (hPSCs) using CRISPR-Cas9 genome editing. RNA-sequencing of the reporter clone, differentiated into GnRH neurons by dual SMAD inhibition and FGF8 treatment, revealed 6461 differentially expressed genes between progenitors and GnRH neurons. Expression of the transcription factor ISL1, one of the top 50 most upregulated genes in the TdTomato-expressing GnRH neurons, was confirmed in 10.5 gestational week-old human fetal GnRH neurons. Among the differentially expressed genes, we detected 15 genes that are implicated in CHH and several genes that are implicated in human puberty timing. Finally, FGF8 treatment in the neuronal progenitor pool led to upregulation of 37 genes expressed both in progenitors and in TdTomato-expressing GnRH neurons, which suggests upstream regulation of these genes by FGF8 signaling during GnRH neuron differentiation. These results illustrate how hPSC-derived human GnRH neuron transcriptomic analysis can be utilized to dissect signaling pathways and gene regulatory networks involved in human GnRH neuron development.This article has an associated First Person interview with the first author of the paper.